JP6821880B2 - Non-aqueous electrolyte and power storage device using lithium salt and its mixture - Google Patents

Description

The present invention relates to a lithium salt having a novel structure and a mixture thereof, and a non-aqueous electrolyte solution and a power storage device using the same, and more specifically, a lithium salt represented by the general formula LiBF _n (NCO) _4-n and a mixture thereof. The present invention also relates to a non-aqueous electrolyte solution and a power storage device using these.

Non-aqueous power sources such as lithium secondary batteries, electric double layer capacitors, and lithium ion capacitors are used in a wide range of applications, from so-called consumer power supplies such as mobile phones and laptop computers to in-vehicle power supplies for driving automobiles and large stationary power supplies. A power storage device using an electrolytic solution has been put into practical use. However, in recent years, there has been an increasing demand for higher performance of power storage devices. For example, in a lithium secondary battery, it is required to achieve various characteristics such as input / output characteristics, charge / discharge rate characteristics, impedance characteristics, cycle characteristics, storage characteristics, continuous charging characteristics, and safety at a high level.

So far, as a means for improving various characteristics of lithium secondary batteries, many technologies have been studied for active materials of positive electrodes and negative electrodes and various battery components such as non-aqueous electrolytes. ..

For example, Patent Document 1 describes a non-aqueous solvent composed of a cyclic carboxylic acid ester, a cyclic carbonate having at least one carbon-carbon unsaturated bond, and a cyclic carbonate having no carbon-carbon unsaturated bond, and the like. A non-aqueous electrolyte solution comprising a solute dissolved in a non-aqueous solvent is disclosed. In Patent Document 1, it is shown that when both LiPF ₆ and LiBF ₄ are used as the solute, the cycle characteristics are improved as compared with the case where LiPF ₆ and LiBF ₄ are used alone.

Further, in Non-Patent Document 1, the non-aqueous electrolyte solution in which LiPF ₆ is dissolved as an electrolyte salt in a non-aqueous solvent and further added with lithium bis (oxalate) borate (LiBOB) is a non-aqueous electrolyte solution to which LiBOB is not added. It has been shown that the capacity retention rate during high temperature cycles is improved as compared with the electrolytic solution.

Further, Non-Patent Document 2 refers to the structure of a film formed by lithium bis (oxalate) borate on the negative electrode surface of a non-aqueous electrolyte secondary battery. According to Non-Patent Document 2, in the lithium oxalate salt, the bond between the atom having a formal negative charge and the ligand (that is, the oxalate skeleton) bonded to the atom is opened by electrochemical reduction, and further another molecule. It has been reported to recombine with.

Japanese Unexamined Patent Publication No. 2005-101003

Journal of Power Sources, 174, 852-855 (2007). Wu et al., Electrochemical and Solid-State Lett. 6, A144 (2003).

As mentioned above, as the demand for higher performance of power storage devices using non-aqueous electrolytes has increased in recent years, further improvement of battery performance, that is, initial input / output characteristics, charge / discharge rate characteristics, impedance characteristics, cycles and storage It is required to improve the capacity retention rate during durability such as continuous charging and the input / output retention rate after durability.

However, in the non-aqueous electrolyte battery using the electrolytic solution described in Patent Document 1 and Non-Patent Document 1, various characteristics such as initial input / output characteristics, capacity retention rate during durability, and input / output characteristics after durability are used. However, it was still hard to say that it was enough.

The reason for this has not been completely clarified at present, but it is speculated as follows. That is, in compounds containing boron in the anion skeleton, such as LiBF ₄ and LiBOB, the decomposition reaction of the solvent and the electrolyte salt is suppressed by the presence of a film formed by the reduction decomposition of the compound on the negative electrode. , The capacity retention rate during the cycle tends to improve. At the same time, since the negative electrode film serves as a resistance component for the insertion / removal reaction of lithium ions, the input / output characteristics after the cycle tend to deteriorate. That is, they are in a trade-off relationship, and there is a desire to break away from this characteristic conflict.

The present invention has been made in view of the background art, and the subject thereof is a novel lithium salt and a mixture thereof that can provide a power storage device having excellent input / output characteristics and durability, and a non-aqueous electrolysis using these. The purpose is to provide a liquid, a power storage device, and the like.

As a result of diligent studies to solve the above problems, the present inventors have created a lithium salt having a new structure, prepared a non-aqueous electrolyte solution containing the lithium salt, and further stored various storage of this non-aqueous electrolyte solution. We have found that the above-mentioned trade-off relationship can be overcome by using it in a device, and have completed the present invention.

That is, the present invention provides, for example, the specific embodiments shown in the following [1] to [10].
[1]
A compound represented by the following general formula (1).
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 3 or less.)

[2]
A non-aqueous electrolyte solution containing at least one compound represented by the following general formula (1).
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 4 or less.)
[3]
It is characterized by further containing at least one selected from the group consisting of a lithium fluorophosphate salt, a boron-containing lithium salt other than the compound represented by the general formula (1), a sulfonic acid lithium salt, and an imide lithium salt. 2] The non-aqueous electrolyte solution according to.
[4]
The non-aqueous electrolyte solution according to the above [2] or [3], which further contains a cyclic carbonate containing at least one of a carbon-carbon unsaturated bond and a fluorine atom.
[5]
A power storage device containing the non-aqueous electrolyte solution according to any one of the above [2] to [4].

[6]
A mixture containing two or more compounds represented by the following general formula (1) and having an average value m of isocyanato substitution number 4-n of 0.1 to 3.9.
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 4 or less.)
[7]
A non-aqueous electrolytic solution represented by the following general formula (1) and containing at least a lithium salt mixture having an isocyanato substitution number 4-n having an average value m of 0.1 to 3.9.
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 4 or less.)
[8]
It is characterized by further containing at least one selected from the group consisting of a lithium fluorophosphate salt, a boron-containing lithium salt other than the compound represented by the general formula (1), a sulfonic acid lithium salt, and an imide lithium salt. 7] The non-aqueous electrolyte solution according to.
[9]
The non-aqueous electrolyte solution according to the above [7] or [8], which further contains a carbonate containing at least one of a carbon-carbon unsaturated bond and a fluorine atom.
[10]
A power storage device containing the non-aqueous electrolyte solution according to any one of the above [7] to [9].

The present inventor has focused on the formation mechanism of a negative electrode film such as a lithium battery and the elementary reaction rate in order to develop a non-aqueous electrolyte solution having excellent various characteristics such as initial input / output characteristics and input / output characteristics after a cycle. Various studies were carried out on the action and effect of various compounds and their combinations.

As a result, a lithium salt having a new structure, that is, a compound represented by the above general formula (1) is created, and this is used as an electrolyte salt for a non-aqueous electrolyte solution to produce a power storage device having excellent input / output characteristics and durability. We built the technology to realize it.

The role of the electrolytic solution in the power storage device is to transport the ion species involved in the electrode reaction at high speed to the counter electrode and to cause a smooth electrochemical reaction on the electrode surface. Therefore, the electrolyte salt usually has a structure that is easily dissolved in a solvent, and is required to promote ion dissociation in the solvent. Further, ion species that do not contribute to the electrode reaction are required to have withstand voltage resistance that does not electrolyze within the operating voltage range of the power storage device. On the other hand, recently reported electrolyte salts are also attempted to improve the durability of power storage devices by actively electrolyzing them on the electrode surface and suppressing further side reactions on the electrodes by the function of the decomposed products. It has been reported.

For example, as described in Non-Patent Document 2, in LiBOB, the bond between an atom having a formal negative charge and a ligand (that is, an oxalate skeleton) bonded to the atom is cleaved by electrochemical reduction, and further. By repeating recombination with other molecules, a thermally and chemically stable film is formed on the surface of the negative electrode. This suppresses side reactions of the solvent and the like, thereby improving the durability of the battery. However, since the above process is triggered by electrochemical reduction, the effect on the original charge / discharge process of the battery cannot be ignored. In addition, the initial coating of LiBOB formed in this process is a mechanism that exerts its effect by covering the surface with molecules with poor ionicity, which have a structure lacking flexibility, and therefore, as a side effect, lithium ion permeability is lowered. Therefore, there is a drawback that the initial output is lowered.

In view of the above reaction, the present inventors searched for a functional group to replace the oxalate skeleton. As a result, it was found that by selecting the isocyanato (NCO) structure as the functional group, both the input / output characteristics and the durability are improved. The NCO group is an electron-withdrawing group, and by appropriately dispersing the negative charge of the quaternary boron compound structure, the solubility in a solvent can be improved. Further, the NCO group can be added by a base reaction, and the strong film formed in this way suppresses the reaction between the negative electrode and the solvent. Therefore, the boron-containing anion having an NCO group is, for example, a molecule of a boron-containing anion having a reduced NCO group and a boron-containing anion having a non-reduced NCO group, which protects the negative electrode by an addition reaction to a functional group on the surface of a carbon negative electrode. It is presumed that the durability is improved as a result of being involved in the protection of the negative electrode by forming a film by the inter-reaction and the combination of these. Since these reactions proceed without electrochemical action, it is not necessary to consider the influence on the original charging / discharging process of the battery.

Further, the reaction proceeds while maintaining the quaternary boron anion structure. Since the above reaction directly protects the surface functional groups having the reaction activity, it has little influence on the permeability of lithium ions, unlike the protective film that simply covers the surface. That is, the film formed by the bonding of the quaternary boron anion structure has a thin and uniform structure, and since the quaternary boron anion structure is maintained, there are advantages such as excellent ionic conductivity. From these facts, it is considered that the protective action of the boron-containing anion having an NCO group contributes to the improvement of the input / output characteristics.

Here, if a fluorine atom is further introduced into the boron-containing anion structure having an NCO group, the fluorine atom has higher electron attraction than the NCO group and further delocalizes the negative charge of the quaternary boron compound. Therefore, the lithium ion permeability on the surface of the negative electrode can be further improved, and high input / output characteristics can be provided.

According to the present invention, it is possible to provide a lithium salt having a novel structure represented by the general formula LiBF _n (NCO) _4-n and a mixture thereof. Then, by using these as an electrolyte salt of a non-aqueous electrolyte solution, it is possible to realize a power storage device or the like having excellent input / output characteristics and durability.

It is a chart which shows the ¹⁹ F-NMR measurement result of the lithium salt of an Example. It is a chart which shows the ¹¹ B-NMR measurement result of the lithium salt of an Example. It is a chart which shows the ESI-MS measurement result of the lithium salt of an Example.

Hereinafter, embodiments of the present invention will be described in detail. The following embodiments are examples (representative examples) of embodiments of the present invention, and the present invention is not limited thereto. Further, the present invention can be arbitrarily modified and implemented without departing from the gist thereof. In this specification, for example, the notation of the numerical range of "1 to 100" includes both the lower limit value "1" and the upper limit value "100". The same applies to the notation of other numerical ranges.

<1. Lithium salt with new structure>
The lithium salt of the present embodiment has a novel structure represented by the following general formula (1). The lithium salt having this novel structure is a borate compound in which n fluorine atoms and (4-n) isocyanato groups are introduced.
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 3 or less.)

Examples of the method for synthesizing the lithium compound represented by the following general formula (1) include, for example, the methods 1) to 3) below, but the method is not particularly limited thereto.
1) A method in which a complex (BF ₃ / Et ₂ O, etc.) of LiOCN and BF ₃ or BF ₃ and a solvent having a low boiling point and an inert substance is reacted alone.
2) A method of precipitating MX by reacting LiBFnX _4-n (X is a halogen atom other than F, n is an integer of 0 or more and 3 or less) and 4-n MOCNs. (M is a cation species such as Ag in which MX is a poorly soluble salt in both water and non-aqueous solvents)
3) A reaction in which LiBF4 is reacted with a Si-NCO compound to produce LiBFn (NCO) _4-n and a Si-F compound.

Among these, for example, when adjusting so that n is 3, the method 1) above, which only requires mixing, is the simplest and preferable. Further, when adjusting so that n becomes 0, the method 3) above is preferable, in which the reaction proceeds reliably. Further, when adjusting so that the average value of n is 1 or 2, the method of 3) above can be used, but since it may be difficult to obtain an appropriate halogen mixed raw material, the method 2) above may be used. Is preferably used.

As the various raw materials used in the above synthesis method, commercially available ones may be used as they are, may be purified and used, or may be produced from other compounds and used. The purity is also not particularly limited, but it is preferable that the purity is higher, preferably 99% by mass, because there is a concern that the performance of the battery or the like may be deteriorated due to the residual impurities derived from the raw material. The above is preferable.

Further, it is preferable that the charging ratio of each raw material does not deviate significantly from the ratio commensurate with the desired n. When the compound represented by the general formula (1) is obtained as a mixture of a plurality of compounds having different values of n, the average value m of the number of isocyanato substitutions (4-n) of the mixture is the preparation of each raw material. By adjusting the ratio and the like, it can be controlled within the range of 0.1 to 3.9, for example. For reasons such as simplicity of operation, it is preferable to obtain a mixture having an average value m of isocyanato substitutions of 2.5 to 3.5 in the method 1) above, and the average number of isocyanato substitutions in the method 2) above. It is preferable to obtain a mixture having a value m of 0 to 3.5, and it is preferable to obtain a mixture having an average value m of the number of isocyanato substitutions of 0.1 to 3.8 in the method 3) above.

In any case, it is preferable to use a solvent from the viewpoint of making the reaction uniform. The solvent is not particularly limited except for a solvent that reacts with various raw materials (for example, a protonic solvent such as water or alcohol), but the solubility of the produced LiBF _n (NCO) _4-n is extremely low. Those that do not exist are preferable because they can react stably.

Preferred solvents include chain carbonate esters such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate; chain carboxylic acid esters such as methyl acetate, ethyl acetate and methyl propionate; methyl methanesulfonate, ethyl methanesulfonate, ethane sulfone. Chain sulfonic acid esters such as methyl acid; Chain nitriles such as acetonitrile and propionitrile; Chain ethers such as diethyl ether, diisopropyl ether and t-butyl methyl ether; tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1 , 3-Dioxane, cyclic ethers such as 1,4-Dioxane; and the like.

Among these, chain carbonate esters such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate; chain carboxylic acid esters such as methyl acetate, ethyl acetate and methyl propionate; and chain nitriles such as acetonitrile and propionitrile; are preferable. Further, dimethyl carbonate, diethyl carbonate, ethyl acetate and acetonitrile are preferable because of their availability. These solvents may be used alone or in combination, but are preferably used alone so as not to complicate the operation.

The ratio of the solvent to the raw material is not particularly limited, but is preferably 100 times or less, more preferably 50 times or less, still more preferably 25 times or less by volume. Further, the volume ratio is preferably 2 times or more, more preferably 3 times or more, still more preferably 5 times or more. If it is within the above range, the production efficiency is excellent, and problems such as hindering the stirring of the insoluble raw material tend to be less likely to occur.

The temperature at which the reaction step of the present embodiment is started is not particularly limited, but is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, still more preferably 60 ° C. or lower. The temperature at which the reaction is carried out is not particularly limited, but is preferably −20 ° C. or higher, more preferably −10 ° C. or higher, still more preferably 0 ° C. or higher. When the temperature at the start of the reaction process of the present embodiment is within the above range, problems such as volatilization of the solvent and occurrence of unexpected side reactions are unlikely to occur, and problems such as a decrease in the reaction rate tend to be suppressed. It is in.

The order in which the raw materials are charged into the reaction system is not particularly limited, but when a raw material insoluble in a solvent such as LiOCN is used, it is preferable to charge the raw materials in advance and suspend them in the solvent. The raw material to be added may not be diluted with a solvent, but may be diluted. However, when a solid soluble in a solvent is added later, it is preferable to dilute the raw material with the solvent.

The time spent for the operation for adding the raw material to be added later is not particularly limited, but is preferably 10 hours or less, more preferably 5 hours or less, still more preferably 1 hour or less. The charging time in the reaction of the present embodiment is not particularly limited, but is preferably 1 minute or longer, more preferably 5 minutes or longer, still more preferably 10 minutes or longer. When the charging time in the reaction step of the present embodiment is within the above range, the production efficiency tends to be excellent.

The temperature at the time of charging in the reaction step of the present embodiment is not particularly limited, but is preferably the starting temperature of + 20 ° C. or lower, more preferably + 10 ° C. or lower, still more preferably + 5 ° C. or lower. The temperature at the time of charging in the reaction of the present embodiment is not particularly limited, but is preferably the starting temperature of −20 ° C. or higher, more preferably −10 ° C. or higher, still more preferably −5 ° C. or higher, and the starting temperature. It is especially preferable to keep it back and forth. When the temperature at the time of charging in the reaction step of the present embodiment is within the above range, problems such as volatilization of the solvent and occurrence of unexpected side reactions and problems such as a decrease in the reaction rate tend to be less likely to occur.

In addition, it is preferable to go through a aging step after charging. The temperature during aging in the aging step is not particularly limited, but is preferably + 100 ° C. or lower, more preferably + 80 ° C. or lower, and further preferably + 50 ° C. or lower with respect to the temperature at the time of reaction. The temperature at the time of aging is not particularly limited, but is preferably + 5 ° C. or higher, more preferably + 10 ° C. or higher, and further preferably + 20 ° C. or higher with respect to the temperature at the time of reaction. When the temperature during aging in the aging step is within the above range, problems such as volatilization of the solvent and occurrence of unexpected side reactions and problems such as a decrease in the reaction rate tend to be less likely to occur.

The time of the aging step is not particularly limited, but is preferably 20 hours or less, more preferably 10 hours or less, still more preferably 5 hours or less. The reaction time in the reaction of the present embodiment is not particularly limited, but is preferably 1 minute or longer, more preferably 10 minutes or longer, still more preferably 30 minutes or longer. When the aging step time is within the above range, the production efficiency tends to be good, and the aging effect tends to be sufficiently obtained.

The atmosphere of the reaction system is not particularly limited, but from the viewpoint of suppressing decomposition of raw materials and products due to moisture, mixing is preferably carried out in an atmosphere in which the outside air is blocked, such as dry air, a nitrogen atmosphere, or an argon atmosphere. It is more preferable to mix in an inert atmosphere. These gases may be sealed after being introduced into the equipment at the start of the reaction process, or may be continuously supplied and discharged into the equipment.

<2. Non-aqueous electrolyte>
<2-1. Lithium salt represented by LiBF _n (NCO) _4-n >
The non-aqueous electrolyte solution of the present embodiment contains at least one lithium salt represented by the above general formula (1). Among these, from the viewpoint of improving the input / output characteristics, LiBF ₃ NCO and LiBF ₂ (NCO) ₂ and LiBF (NCO) ₃ are preferable, LiBF ₃ NCO and LiBF ₂ (NCO) ₂ are more preferable, and LiBF ₃ NCO is further preferable. preferable. From the viewpoint of improving durability, LiBF ₂ (NCO) ₂ , LiBF (NCO) ₃ and LiB (NCO) ₄ are preferable, LiBF (NCO) ₃ and LiB (NCO) ₄ are more preferable, and LiB (NCO) ₄ is more preferable. Further, from the viewpoint of achieving both input / output characteristics and durability, LiBF ₃ NCO and LiBF ₂ (NCO) ₂ and LiBF (NCO) ₃ are preferable, LiBF ₃ NCO and LiBF ₂ (NCO) ₂ are more preferable, and LiBF ₂ ( NCO) ₂ is more preferred. The non-aqueous electrolyte solution of the present embodiment may contain a plurality of types of lithium salts represented by the above general formula (1).

The total content of LiBF _n (NCO) _4-n in the non-aqueous electrolyte solution is not particularly limited, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0. .2% by mass, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 8% by mass or less, more preferably 6% by mass or less, still more preferably. It is 5% by mass or less. Within the above concentration range, the ionic conductivity tends to be optimized, the electrode surface film is appropriately formed when used in a power storage device, and the balance between input / output characteristics and durability is good. It tends to be.

_The non-aqueous electrolyte containing LiBF _{n (NCO) 4-n} is, LiBF _n in a non-aqueous system in a solvent LiBF _n may be prepared by dissolving the _{(NCO) 4-n,} also a non-aqueous solvent The solution itself (non-aqueous electrolyte solution) obtained by synthesizing (NCO) _4-n may be used. That is, it is also preferable to use the reaction solution containing LiBF _n (NCO) _4-n as it is as a non-aqueous electrolytic solution. At this time, it is assumed that a storage device using a non-aqueous electrolyte solution that produces LiBF _n (NCO) _4-n is also included.

<2-2. Other electrolyte salts>
The non-aqueous electrolyte solution in the present embodiment contains LiBF _n NCO _(4-n) as an electrolyte salt, but may be abbreviated as another electrolyte salt (hereinafter, referred to as “another electrolyte salt”). ) May be further contained. The other electrolyte salt in the present embodiment is not particularly limited as long as it is known to be used for this purpose, and any one can be used. Specific examples of other electrolyte salts include the following.

Inorganic lithium salts such as LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ ;
Lithium fluorophosphates other than LiPF ₆ such as LiPF ₆ , LiPO ₃ F, LiPO ₂ F ₂ ;
Lithium tungstic acid salts such as LiWOF ₅ ;
HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ Lithium carboxylic acid salts such as CO ₂ Li, CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li;
FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ Li and other lithium sulfonic acid salts;
LiN (FCO ₂ ) ₂ , LiN (FCO) (FSO ₂ ), LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅₎ Lithium imides such as SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) salts;
Lithiummethide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ;
Lithium oxalate salts such as lithium difluorooxalate borate, lithium bis (oxalate) borate, lithium tetrafluorooxalat oxalate, lithium difluorobis (oxalate) phosphate, lithium tris (oxalat) phosphate;
In addition, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ Fluorine-containing organic lithium salts such as;
And so on.

Among these, inorganic lithium salts, lithium fluorophosphates, and sulfonic acid are considered from the viewpoint of further enhancing the effect of improving input / output characteristics, charge / discharge rate charge / discharge characteristics, and impedance characteristics after durability tests such as high temperature storage test and cycle test. Lithium acid salts, lithium imide salts, lithium oxalate salts and the like are preferable.

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , LiPO ₃ F, LiPO ₂ F ₂ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ). ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , Lithium cyclic 1,2-perfluoroethanedisulfonylimide, Lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC ( FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , Lithium difluorooxalatobolate, Lithium bis (oxalate) borate, Lithium tetrafluorooxalatophosphate, Lithium difluorobis ( Oxalato) phosphate, lithium tris (oxalate) phosphate and the like are particularly preferable because they have the effect of improving input / output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics and the like.

The total content of these other electrolyte salts in the non-aqueous electrolyte solution is not particularly limited, but is usually 8% by mass or more, preferably 8.5% by mass or more, and more preferably 9% by mass or more. The upper limit thereof is usually 18% by mass or less, preferably 17% by mass or less, and more preferably 16% by mass or less. When the total concentration of other electrolyte salts is within the above range, the electric conductivity tends to be appropriate for battery operation.

In addition, other electrolyte salts may be used alone or in combination of two or more and in any ratio. Preferred examples of the combined use of two or more are LiPF ₆ and LiBF ₄ , LiPF ₆ and LiPO ₂ F ₂ , LiPF ₆ and FSO ₃ Li, LiPF ₆ and LiN (FSO ₂ ) ₂ , LiPF ₆ and LiN (CF). ₃ SO ₂ ) ₂ , LiPF ₆ and Lithium Bis (Oxalato) Borate, LiPF ₆ and Lithium Tetrafluorooxarat Phosphate, LiPF ₆ and Lithium Difluorobis (Oxalato) Phosphate, LiPF ₆ and LiBF ₄ and LiPO ₂ F ₂ , LiPF ₆ and LiBF ₄ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F ₂ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F ₂ and lithium bis (oxalate) borate, LiPF ₆ and LiPO ₂ F ₂ and lithium difluorobis (oxalate) ) Phosphate, LiPF ₆ and LiPO ₂ F ₂ and LiN (FSO ₂ ) ₂ , LiPF ₆ and LiPO ₂ F ₂ and LiN (CF ₃ SO ₂ ) ₂ , LiPF ₆ and FSO ₃ Li and Lithium Bis (Oxalato) Borate, LiPF ₆ and FSO ₃ Li are used in combination with lithium difluorobis (oxalate) phosphate, and these combinations have the effect of improving input / output characteristics, high-temperature storage characteristics, and cycle characteristics. In this case, the content of LiPF ₆ is preferably 7% by mass or more, more preferably 7.5% by mass or more, still more preferably 8% by mass or more, preferably 16% by mass or less, and more preferably 15% by mass or less. More preferably, it is 14% by mass or less. The contents of LiBF ₄ , LiPO ₂ F ₂ , FSO ₃ Li, LiN (FSO ₂ ) ₂ LiN (CF ₃ SO ₂ ) ₂ , lithium bis (oxalate) borate, and lithium difluorobis (oxalate) phosphate are preferable. Is 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less. Is. When the content of LiPF ₆ is within the above-mentioned preferable range, the total ion content in the non-aqueous electrolytic solution and the viscosity of the electrolytic solution tend to be in an appropriate balance, and the battery does not excessively reduce the ionic conductivity. The internal impedance becomes low, and the effect of improving the input / output characteristics, cycle characteristics, and storage characteristics by blending LiPF ₆ tends to be more easily exhibited.

Here, the preparation of the electrolytic solution when the oxofluorophosphate is contained in the electrolytic solution may be carried out by a known method and is not particularly limited. For example, a method of adding an oxofluorophosphate synthesized by a separately known method to an electrolytic solution containing LiPF ₆ or water is allowed to coexist in battery components such as an active material and a electrode plate described later, and LiPF is used. Examples thereof include a method of generating oxofluorophosphate in the system when assembling a battery using an electrolytic solution containing ₆ . In this embodiment, any method may be used.

The method for measuring the content of oxofluorophosphate in the above-mentioned non-aqueous electrolyte solution and non-aqueous electrolyte solution battery is not particularly limited, and any known method can be used. Specifically, and ion chromatography, ^{19 F} nuclear magnetic resonance spectroscopy (hereinafter, sometimes referred to as "NMR".), And the like.

<2-3. Non-aqueous solvent>
Like a general non-aqueous electrolyte solution, the non-aqueous electrolyte solution of the present embodiment usually contains a non-aqueous solvent that dissolves the above-mentioned electrolyte salt as its main component. The non-aqueous solvent used here is not particularly limited, and a known organic solvent can be used. Examples of the organic solvent include saturated cyclic carbonate, chain carbonate, chain carboxylic acid ester, cyclic carboxylic acid ester, ether compound, sulfone compound and the like, but are not particularly limited thereto. These can be used alone or in combination and in proportions of two or more.

<2-3-1. Saturated cyclic carbonate>
Examples of the saturated cyclic carbonate include those having an alkylene group having 2 to 4 carbon atoms.

Specifically, examples of the saturated cyclic carbonate having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate, butylene carbonate and the like. Among these, ethylene carbonate and propylene carbonate are preferable from the viewpoint of improving battery characteristics resulting from the improvement of the degree of lithium ion dissociation. As the saturated cyclic carbonate, one kind may be used alone, or two or more kinds may be used in any combination and ratio.

The content of the saturated cyclic carbonate is not particularly limited, but the lower limit of the content when one type is used alone is usually 3% by volume or more, preferably 5% by volume or more in 100% by volume of the non-aqueous solvent. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte solution is avoided, and the large current discharge characteristics of lithium batteries and the like, the stability with respect to the negative electrode, and the cycle characteristics are in a good range. There is a tendency. The upper limit is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting this range, the viscosity of the non-aqueous electrolyte solution becomes an appropriate range, the decrease in ionic conductivity is suppressed, the input / output characteristics of lithium batteries, etc. are further improved, and the durability such as cycle characteristics and storage characteristics is improved. It tends to improve further.

Further, the saturated cyclic carbonate can be used in any combination of two or more kinds. One of the preferred combinations is a combination of ethylene carbonate and propylene carbonate. In this case, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, more preferably 95: 5 to 50:50. Further, the lower limit of the content of propylene carbonate with respect to the whole non-aqueous solvent is usually 1% by volume or more, preferably 2% by volume or more, and more preferably 3% by volume or more. The upper limit thereof is usually 30% by volume or less, preferably 25% by volume or less, and more preferably 20% by volume or less. If propylene carbonate is contained within this range, the low temperature characteristics tend to be further improved.

<2-3-2. Chain carbonate>
As the chain carbonate, for example, one having 3 to 7 carbon atoms is preferable.

Specifically, examples of the chain carbonate having 3 to 7 carbon atoms include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate, methyl-n-propyl carbonate, and the like. Examples thereof include n-butylmethyl carbonate, isobutylmethyl carbonate, t-butylmethyl carbonate, ethyl-n-propyl carbonate, n-butylethyl carbonate, isobutylethyl carbonate, t-butylethyl carbonate and the like.

Among these, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethylmethyl carbonate and methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate and ethylmethyl are particularly preferable. It is carbonate.

In addition, chain carbonates having a fluorine atom (hereinafter, may be abbreviated as "fluorinated chain carbonate") can also be preferably used. The number of fluorine atoms contained in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

Examples of the fluorinated dimethyl carbonate derivative include fluoromethylmethyl carbonate, difluoromethylmethyl carbonate, trifluoromethylmethyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate and the like.

Examples of the fluorinated ethyl methyl carbonate derivative include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, and 2,2,2-tri. Examples thereof include fluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate and the like.

Examples of the fluorinated diethyl carbonate derivative include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, and ethyl- (2,2,2-trifluoro). Ethyl) carbonate, 2,2-difluoroethyl-2'-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2'-fluoroethyl carbonate, 2,2 Examples thereof include 2-trifluoroethyl-2', 2'-difluoroethyl carbonate and bis (2,2,2-trifluoroethyl) carbonate.

As the chain carbonate, one type may be used alone, or two or more types may be used in any combination and ratio.

The content of the chain carbonate is not particularly limited, but is usually 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more in 100% by volume of the non-aqueous solvent. Further, it is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the content of the chain carbonate in the above range, the viscosity of the non-aqueous electrolyte solution becomes in an appropriate range, the decrease in ionic conductivity is suppressed, and the input / output characteristics and charge / discharge rate characteristics of lithium batteries and the like are good. It tends to be in the range. Further, it is easy to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte solution, and the input / output characteristics and charge / discharge rate characteristics of a lithium battery or the like tend to be in a good range.

Further, by combining ethylene carbonate with a specific chain carbonate at a specific content, the battery performance can be remarkably improved. For example, when dimethyl carbonate and ethyl methyl carbonate are selected as specific chain carbonates, the content of ethylene carbonate is not particularly limited, but is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less. It is preferably 40% by volume or less, and the content of dimethyl carbonate is not particularly limited, but is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. The content of ethyl methyl carbonate is not particularly limited, but is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. By setting the content within the above range, it is possible to improve the ionic conductivity by lowering the viscosity of the non-aqueous electrolyte solution while lowering the low temperature precipitation temperature of the electrolyte, and high input / output characteristics can be obtained even at low temperatures. It tends to be easy.

<2-3-3. Chain carboxylic acid ester>
Examples of the chain carboxylic acid ester include those having a total carbon number of 3 to 7 in the structural formula.

Specifically, methyl acetate, ethyl acetate, -n-propyl acetate, isopropyl acetate, -n-butyl acetate, isobutyl acetate, -t-butyl acetate, methyl propionate, ethyl propionate, -n-propyl propionate, Isopropyl propionate, -n-butyl propionate, isobutyl propionate, -t-butyl propionate, methyl butyrate, ethyl butyrate, -n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, -n-isobutyrate Examples thereof include propyl and isopropyl isobutyrate.

Among these, methyl acetate, ethyl acetate, -n-propyl acetate, -n-butyl acetate, methyl propionate, ethyl propionate, -n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate and the like have viscosities. It is preferable from the viewpoint of improving the ionic conductivity due to the decrease and suppressing the battery swelling during durability such as cycle and storage.

The content of the chain carboxylic acid ester is not particularly limited, but is usually 0.5% by volume or more, preferably 1% by volume or more, and usually 80% by volume or less, preferably 70% by volume in 100% by volume of the non-aqueous solvent. It is less than or equal to the volume. When the content of the chain carboxylic acid ester is within the above range, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the input / output characteristics and charge / discharge rate characteristics of the lithium battery and the like tend to be improved. In addition, the increase in negative electrode resistance is suppressed, and the input / output characteristics and charge / discharge rate characteristics of lithium batteries and the like tend to be in a good range.

When a chain carboxylic acid ester is used, it is preferably used in combination with a cyclic carbonate, and more preferably a combination of a cyclic carbonate and a chain carbonate.

For example, when the cyclic carbonate and the chain carboxylic acid ester are used in combination, the content of the cyclic carbonate is not particularly limited, but is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less, preferably 40% by volume. The content of the chain carboxylic acid ester is not particularly limited, but is usually 20% by volume or more, preferably 30% by volume or more, and usually 55% by volume or less, preferably 50% by volume or less. When the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester are used in combination, the content of the cyclic carbonate is not particularly limited, but is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less. It is preferably 40% by volume or less, and the content of the chain carbonate is not particularly limited, but is usually 25% by volume or more, preferably 30% by volume or more, and usually 84% by volume or less, preferably 80% by volume or less. .. By setting the content within the above range, it is possible to improve the ionic conductivity by lowering the viscosity of the non-aqueous electrolyte solution while lowering the low temperature precipitation temperature of the electrolyte, and even higher input / output characteristics can be obtained even at low temperatures. It tends to be easy, and battery swelling tends to be suppressed.

<2-3-4. Cyclic carboxylic acid ester>
Examples of the cyclic carboxylic acid ester include those having a total carbon atom number of 3 to 12 in the structural formula.

Specific examples thereof include gamma-butyrolactone, gamma valerolactone, gamma caprolactone, and epsilon caprolactone. Among these, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

The content of the cyclic carboxylic acid ester is not particularly limited, but is usually 3% by volume or more, preferably 5% by volume or more, and usually 60% by volume or less, preferably 50% by volume or less in 100% by volume of the non-aqueous solvent. Is. When the content of the cyclic carboxylic acid ester is within the above range, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the input / output characteristics and charge / discharge rate characteristics of the lithium battery and the like tend to be improved. In addition, the viscosity of the non-aqueous electrolyte solution is in an appropriate range, the decrease in electrical conductivity is avoided, the increase in negative electrode resistance is suppressed, and the input / output characteristics and charge / discharge rate characteristics of lithium batteries and the like tend to be in a good range. is there.

<2-3-5. Ether compounds>
As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms are preferable.

Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, and ethyl. (2-Fluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2) -Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoro) Ethyl) ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3- Tetrafluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl) (3-fluoro) -N-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ) Ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether, (2,2,2) -Trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2- Trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ) Ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1,1,2) , 2-Tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-Tetrafluoroethyl) (2,2,3,3-tetrafluoro-n-) (Propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propyl Ether, (n-propyl) (3-fluoro-n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3) , 3-Tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, ( 3-Fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether , (3-Fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3 3,3-Trifluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3) 3,3-Pentafluoro-n-propyl) ether, di (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2) , 2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxy Methoxy, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) ) Methoxy, ethoxy (2,2,2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2) , 2,2-Trifluoroethoxy) methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2) -Trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) Etan, methoxy (2,2,2-trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethane) Xi) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2) -Fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2) 2,2-Trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) Examples thereof include ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether and diethylene glycol dimethyl ether.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 1 , 4-Dioxane and the like, and fluorinated compounds thereof.

Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvation ability to lithium ions and have ionic dissociability. It is preferable in terms of improvement. Particularly preferred are dimethoxymethane, diethoxymethane, and ethoxymethoxymethane because of their low viscosity and high ionic conductivity.

The content of the ether compound is not particularly limited, and is usually 0.5% by volume or more, preferably 1% by volume or more, more preferably 2% by volume or more, and usually 30% by volume in 100% by volume of the non-aqueous solvent. Hereinafter, it is preferably 25% by volume or less, more preferably 20% by volume or less. When the content of the ether-based compound is within the above-mentioned preferable range, it is easy to secure the effect of improving the lithium ion dissociation degree of the chain ether and improving the ionic conductivity due to the decrease in viscosity. Further, when the negative electrode active material is a carbonaceous material, the phenomenon that the chain ether is co-inserted together with the lithium ion can be suppressed, so that the input / output characteristics and the charge / discharge rate characteristics tend to be in an appropriate range.

<2-3-6. Sulfone compounds>
As the sulfone compound, for example, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.

Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones, which are monosulfone compounds; and trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones, which are disulfone compounds. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

As the sulfolanes, sulfolanes and / or sulfolane derivatives (hereinafter, sulfolanes may be abbreviated as "sulfolanes") are preferable. The sulfolane derivative is preferably one in which one or more hydrogen atoms bonded on the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group.

Specifically, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5- Difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro- 3-Methyl sulfolane, 4-fluoro-2-methyl sulfolane, 5-fluoro-3-methyl sulfolane, 5-fluoro-2-methyl sulfolane, 2-fluoromethyl sulfolane, 3-fluoromethyl sulfolane, 2-difluoromethyl sulfolane, 3-Difluoromethyl sulfolane, 2-trifluoromethyl sulfolane, 3-trifluoromethyl sulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro- 3- (Trifluoromethyl) sulfolane, 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable because they have high ionic conductivity and high input / output characteristics can be easily obtained.

Examples of the chain sulfone include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, and n-. Butylmethylsulfone, n-butylethylsulfone, t-butylmethylsulfone, t-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, Trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (tri) Fluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone , Trifluoroethyl-n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, penta Fluoroethyl-n-butyl sulfone, pentafluoroethyl-t-butyl sulfone and the like can be mentioned.

Among these, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl. Methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl Pentafluoroethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, trifluoromethyl -T-Butyl sulfone or the like is preferable because it has high ionic conductivity and high input / output characteristics can be easily obtained.

The content of the sulfone compound is not particularly limited, but is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more in 100% by volume of the non-aqueous solvent, and also. It is usually 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less. When the content of the sulfone compound is within the above range, the effect of improving durability such as cycle characteristics and storage characteristics can be easily obtained, the viscosity of the non-aqueous electrolyte solution is within an appropriate range, and the electrical conductivity is lowered. Is easy to avoid, and the input / output characteristics and charge / discharge rate characteristics of lithium batteries and the like tend to be in an appropriate range.

<2-4. Auxiliary agent>
The non-aqueous electrolyte solution of the present embodiment includes a cyclic carbonate having a carbon-carbon unsaturated bond, a fluorinated unsaturated cyclic carbonate, a cyclic sulfonic acid ester compound, a compound having a cyano group, a diisocyanato compound, a carboxylic acid anhydride, and an overcharge. It may contain an inhibitor, an auxiliary agent other than these, and the like.

<2-4-1. Cyclic carbonate containing at least one of carbon-carbon unsaturated bond and fluorine atom>
The non-aqueous electrolyte solution of the present embodiment further includes a cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter, may be abbreviated as “unsaturated cyclic carbonate”) and a cyclic carbonate containing a fluorine atom. It may contain at least one.

The cyclic carbonate having a carbon-carbon unsaturated bond is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon unsaturated bond, and a carbonate having an arbitrary carbon-carbon unsaturated bond can be used. The cyclic carbonate having a substituent having an aromatic ring is also included in the cyclic carbonate having a carbon-carbon unsaturated bond. The method for producing the unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production.

Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, phenyl carbonates, vinyl carbonates, allyl carbonates and the like.

Examples of the vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinyl vinylene carbonate, allyl vinylene carbonate and the like.

Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond include vinyl ethylene carbonate, 4,5-divinylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, and the like. Examples thereof include ethynyl ethylene carbonate and 4,5-diethynyl ethylene carbonate.

Among these, vinylene carbonates, ethylene carbonate substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond are preferable, and vinylene carbonate, 4,5-diphenylvinylene carbonate, and 4,5-dimethylvinylene carbonate are particularly preferable. , Vinyl ethylene carbonate and ethynyl ethylene carbonate are more preferably used because they easily form a stable interface protection film.

The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary. The molecular weight of the unsaturated cyclic carbonate is usually 50 or more, preferably 80 or more, and usually 250 or less, preferably 150 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolyte solution tends to be easily ensured.

As the unsaturated cyclic carbonate, one type may be used alone, or two or more types may be used in any combination and ratio. The content of the unsaturated cyclic carbonate is not particularly limited and is arbitrary. The content of the unsaturated cyclic carbonate is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further, in 100% by mass of the non-aqueous electrolyte solution. It is preferably 0.2% by mass or more, and usually 10% by mass or less, preferably 8% by mass or less, and more preferably 5% by mass or less. Within the above range, the effect of improving high temperature storage characteristics, cycle characteristics, and the like tends to be sufficiently exhibited.

The cyclic carbonate having a fluorine atom (hereinafter, may be abbreviated as "fluorinated cyclic carbonate") is not particularly limited as long as it is a cyclic carbonate having a fluorine atom.

Examples of the fluorinated cyclic carbonate include a derivative of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, and examples thereof include an ethylene carbonate derivative. Examples of the ethylene carbonate derivative include ethylene carbonate or a fluorinated product of ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms), among which 1 to 8 fluorine atoms are present. Is preferable.

Specifically, monofluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4- Fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate , 4- (Fluoromethyl) -4-fluoroethylene carbonate, 4- (Fluoromethyl) -5-fluoroethylene carbonate, 4-Fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethyl Ethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate and the like can be mentioned.

Among these, at least one selected from the group consisting of monofluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,5-difluoroethylene carbonate and 4,5-difluoro-4,5-dimethylethylene carbonate is high. It is more preferable because it gives ionic conductivity and tends to preferably form an interface protective film.

As the fluorinated cyclic carbonate, one type may be used alone, or two or more types may be used in any combination and ratio. The content of the fluorinated cyclic carbonate is not particularly limited and is arbitrary, but is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.01% by mass or more in 100% by mass of the non-aqueous electrolyte solution. It is 0.1% by mass or more, and usually 85% by mass or less, preferably 80% by mass or less, and more preferably 75% by mass or less.

The fluorinated cyclic carbonate may be used as a main solvent or a secondary solvent of the non-aqueous electrolyte solution. The content of the fluorinated cyclic carbonate when used as a main solvent is usually 8% by mass or more, preferably 10% by mass or more, and more preferably 12% by mass or more in 100% by mass of the non-aqueous electrolyte solution. In addition, it is usually 85% by mass or less, preferably 80% by mass or less, and more preferably 75% by mass or less. Within this range, the effect of improving the cycle characteristics is likely to be sufficiently exhibited, and the decrease in the discharge capacity retention rate tends to be suppressed. The content of the fluorinated cyclic carbonate when used as a secondary solvent is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.01% by mass or more, based on 100% by mass of the non-aqueous electrolyte solution. Is 0.1% by mass or more, and is usually 8% by mass or less, preferably 6% by mass or less, and more preferably 5% by mass or less. Within this range, the effect of improving cycle characteristics and high-temperature storage characteristics tends to be sufficiently exhibited.

<2-4-2. Fluorinated unsaturated cyclic carbonate>
As the fluorinated cyclic carbonate, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter, may be abbreviated as "fluorinated unsaturated cyclic carbonate") can be used. The fluorinated unsaturated cyclic carbonate is not particularly limited. Of these, those having one or two fluorine atoms are preferable. The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production.

Examples of the fluorinated unsaturated cyclic carbonate include a vinylene carbonate derivative, an ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon unsaturated bond, and the like.

Examples of the vinylene carbonate derivative include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4,5-difluoroethylene carbonate and the like.

Examples of the ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon unsaturated bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, and 4,4-difluoro-4. -Vinyl ethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4-fluoro-4-phenyl Examples thereof include ethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate and the like.

The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary. The molecular weight of the fluorinated unsaturated cyclic carbonate is usually 50 or more, preferably 80 or more, and usually 250 or less, preferably 150 or less. Within this range, the solubility of the fluorinated cyclic carbonate in the non-aqueous electrolyte solution tends to be easily ensured.

As the fluorinated unsaturated cyclic carbonate, one type may be used alone, or two or more types may be used in any combination and ratio. The amount of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary. The content of the fluorinated unsaturated cyclic carbonate is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 0.2% by mass or more, based on 100% by mass of the non-aqueous electrolyte solution. , Usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less. Within this range, the effect of improving cycle characteristics tends to be sufficiently exhibited.

<2-4-3. Cyclic sulfonic acid ester compound>
The type of the cyclic sulfonic acid ester compound is not particularly limited, but a compound represented by the following general formula (2) is preferable. The method for producing the cyclic sulfonic acid ester compound is not particularly limited, and a known method can be arbitrarily selected for production.

(In the general formula (2), R ⁵ and R ⁶ are each independently composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. represents an organic group, ^{R 5} and ^{R 6} are each -O-SO ₂ - together may contain an unsaturated bond).

Here, R ⁵ and R ⁶ are preferably organic groups composed of atoms composed of carbon atoms, hydrogen atoms, oxygen atoms, and sulfur atoms, and among them, hydrocarbon groups having 1 to 3 carbon atoms, -O-SO ₂ - is preferably an organic group having.

The molecular weight of the cyclic sulfonic acid ester compound is not particularly limited and is arbitrary. The molecular weight of the cyclic sulfonic acid ester compound is usually 100 or more, preferably 110 or more, and usually 250 or less, preferably 220 or less. Within this range, the solubility of the cyclic sulfonic acid ester compound in the non-aqueous electrolyte solution tends to be easily ensured.

Specific examples of the compound represented by the above general formula (2) include, for example,
1,3-Propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone , 2-Methyl-1,3-Propane Sultone, 3-Methyl-1,3-Propane Sultone, 1-Propen-1,3-Sultone, 2-Propen-1,3-Sultone, 1-Fluoro-1-Propen -1,3-sultone, 2-fluoro-1-propen-1,3-sultone, 3-fluoro-1-propen-1,3-sultone, 1-fluoro-2-propen-1,3-sultone, 2 -Fluoro-2-propen-1,3-sultone, 3-fluoro-2-propen-1,3-sultone, 1-methyl-1-propen-1,3-sultone, 2-methyl-1-propen-1 , 3-Sultone, 3-Methyl-1-propen-1,3-Sultone, 1-Methyl-2-Propen-1,3-Sultone, 2-Methyl-2-Propen-1,3-Sultone, 3-Methyl -2-Propen-1,3-sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro -1,4-Butansultone, 1-Methyl-1,4-Butansultone, 2-Methyl-1,4-Butansultone, 3-Methyl-1,4-Butansultone, 4-Methyl-1,4-Butansultone, 1-Butene -1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1 , 4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1,4-sultone, 2-fluoro -2-buten-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1-fluoro-3-butene-1,4 -Sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1 -Butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone , 1-Methyl-2-butene-1,4 −Sulton, 2-methyl-2-butene-1,4-sulton, 3-methyl-2-butene-1,4-sulton, 4-methyl-2-butene-1,4-sulton, 1-methyl-3 − Butene-1,4-sulton, 2-methyl-3-butene-1,4-sulton, 3-methyl-3-butene-1,4-sulton, 4-methyl-3-butene-1,4-sulton , 1,5-Pentane Sulton, 1-Fluoro-1,5-Pentane Sulton, 2-Fluoro-1,5-Pentane Sulton, 3-Fluoro-1,5-Pentane Sulton, 4-Fluoro-1,5-Pentane Sulton, 5-fluoro-1,5-pentane sulton, 1-methyl-1,5-pentane sulton, 2-methyl-1,5-pentane sulton, 3-methyl-1,5-pentane sulton, 4-methyl- 1,5-Pentane Sulton, 5-Methyl-1,5-Pentane Sulton, 1-Pentane-1,5-Sulton, 2-Pentane-1,5-Sulton, 3-Penten-1,5-Sulton, 4- Pentane-1,5-sulton, 1-fluoro-1-pentene-1,5-sulton, 2-fluoro-1-pentane-1,5-sulton, 3-fluoro-1-pentene-1,5-sulton, 4-Fluoro-1-pentane-1,5-sulton, 5-fluoro-1-pentane-1,5-sulton, 1-fluoro-2-pentene-1,5-sulton, 2-fluoro-2-pentene- 1,5-Sulton, 3-Fluoro-2-pentene-1,5-Sulton, 4-Fluoro-2-Pentane-1,5-Sulton, 5-Fluoro-2-Pentane-1,5-Sulton, 1- Fluoro-3-pentane-1,5-sultone, 2-fluoro-3-pentane-1,5-sulton, 3-fluoro-3-pentane-1,5-sulton, 4-fluoro-3-penten-1, 5-Sulton, 5-Fluoro-3-pentane-1,5-Sulton, 1-Fluoro-4-Pentane-1,5-Sulton, 2-Fluoro-4-Pentane-1,5-Sulton, 3-Fluoro- 4-Pentane-1,5-sulton, 4-fluoro-4-pentene-1,5-sulton, 5-fluoro-4-pentane-1,5-sulton, 1-methyl-1-pentene-1,5- Sulton, 2-methyl-1-pentane-1,5-sulton, 3-methyl-1-pentane-1,5-sulton, 4-methyl-1-pentane-1,5-sulton, 5-methyl-1- Pentane-1,5-sulton, 1-methyl -2-Pentene-1,5-sulton, 2-Methyl-2-pentene-1,5-sulton, 3-Methyl-2-pentene-1,5-sulton, 4-Methyl-2-pentene-1,5 -Sulton, 5-methyl-2-pentene-1,5-sulton, 1-methyl-3-pentene-1,5-sulton, 2-methyl-3-pentene-1,5-sulton, 3-methyl-3 -Pentene-1,5-sulton, 4-methyl-3-pentene-1,5-sulton, 5-methyl-3-pentene-1,5-sulton, 1-methyl-4-pentene-1,5-sulton , 2-Methyl-4-pentene-1,5-sulton, 3-Methyl-4-pentene-1,5-sulton, 4-Methyl-4-pentene-1,5-sulton, 5-Methyl-4-pentene -1,5-sulton, 1,2-oxathiolane-2,2-dioxide-4-yl-acetate, 1,2-oxathiolane-2,2-dioxide-4-yl-propionate, 5-methyl-1,2 Sulton compounds such as −oxathiolane-2,2-dioxide-4-one-2,2-dioxide, 5,5-dimethyl-1,2-oxathiolane-2,2-dioxide-4-one-2,2-dioxide ;

Sulfate compounds such as methylene sulfate, ethylene sulfate, and propylene sulfate;

Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;

1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazole-2,2-dioxide , 5H-1,2,3-oxathiazole-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 4-methyl-1,2,4-oxathiazolidine-2,2- Dioxide, 3H-1,2,4-oxathiazole-2,2-dioxide, 5H-1,2,4-oxathiazole-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide , 5-Methyl-1,2,5-oxathiazolidine-2,2-dioxide, 3H-1,2,5-oxathiazole-2,2-dioxide, 5H-1,2,5-oxathiazole-2, 2-Dioxide, 1,2,3-oxathiadinane-2,2-dioxide, 3-methyl-1,2,3-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine- 2,2-Dioxide, 1,2,4-oxathiadinane-2,2-dioxide, 4-methyl-1,2,4-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,4- Oxathiazine-2,2-dioxide, 3,6-dihydro-1,2,4-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,4-oxathiazine-2,2-dioxide, 1, 2,5-oxathiadinane-2,2-dioxide, 5-methyl-1,2,5-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,5-oxathiazine-2,2-dioxide, 1,2,6-oxathiadinane-2, 2-Dioxide, 6-methyl-1,2,6-oxathiadinane-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide, 3,4-dihydro-1, Nitrogen-containing compounds such as 2,6-oxathiazine-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide;

1,2,3-oxathiaphoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosrane-2,2-dioxide, 3-methyl-1,2,3-oxachi Aphoslan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosrane-2,2,3-trioxide, 1,2,4-oxathiaphosrane-2,2-dioxide , 4-Methyl-1,2,4-oxathiaphosrane-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosrane-2,2,4-trioxide, 4-methoxy-1 , 2,4-oxathiaphoslan-2,2,4-trioxide, 1,2,5-oxathiaphosrane-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosrane- 2,2-Dioxide, 5-Methyl-1,2,5-oxathiaphosrane-2,2,5-trioxide, 5-methoxy-1,2,5-oxathiaphosrane-2,2,5- Trioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3- Oxatiaphosphinan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 1,2,4-oxathiaphosphinan-2,2 -Dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 4-methyl -1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 4-methoxy-1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 3-methoxy-1 , 2,4-oxathiaphosphinan-2,2,3-trioxide, 1,2,5-oxathiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan- 2,2-Dioxide, 5-Methyl-1,2,5-oxathiaphosphinan-2,2,3-trioxide, 5-methoxy-1,2,5-oxathiaphosphinan-2,2,3- Trioxide, 1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6- Oxatiaphosphinan-2,2,3-trioxide, 6-methoxy-1,2,6-oxatiaphosphinan-2,2 , 3-Trioxide and other phosphorus-containing compounds;
And so on.

Of these
1,3-Propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propen-1,3-sultone, 1-Fluoro-1-propen-1,3-sultone, 2-fluoro-1-propen-1,3-sultone, 3-fluoro-1-propen-1,3-sultone, 1,4-butane sultone, methylenemethane Disulfonate and ethylenemethane disulfonate are preferable from the viewpoint of improving storage characteristics, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1. , 3-Propane sultone, 1-propen-1,3-sultone are more preferable.

As the cyclic sulfonic acid ester compound, one type may be used alone, or two or more types may be used in any combination and ratio. The content of the cyclic sulfonic acid ester compound in the entire non-aqueous electrolyte solution of the present embodiment is not particularly limited and is arbitrary. With respect to the non-aqueous electrolyte solution of the present embodiment, it is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, and more. , Usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within the above range, the cycle characteristics, high temperature storage characteristics, and the like are likely to be sufficiently improved, and the battery swelling tends to decrease.

<2-4-4. Compound with cyano group>
The type of the compound having a cyano group is not particularly limited as long as it is a compound having a cyano group in the molecule, but the compound represented by the following general formula (3) is more preferable. The method for producing the compound having a cyano group is not particularly limited, and a known method can be arbitrarily selected for production.

(In the general formula (3), T represents an organic group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and U is a substitution. It is a V-valent organic group having 1 to 10 carbon atoms which may have a group. V is an integer of 1 or more, and when V is 2 or more, T may be the same as or different from each other. Good.)

The molecular weight of the compound having a cyano group is not particularly limited and is arbitrary. The molecular weight of the compound having a cyano group is usually 40 or more, preferably 45 or more, more preferably 50 or more, and usually 200 or less, preferably 180 or less, more preferably 170 or less. Within this range, the solubility of the compound having a cyanide group in a non-aqueous electrolyte solution tends to be easily ensured.

Specific examples of the compound represented by the above general formula (3) include, for example,
Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile 2-methylbutyronitrile, trimethylnitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, Crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butennitril, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, 2-hexenenitrile, fluoro Acetonitrile, difluoronitrile, trifluoronitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, 1,2,3-propanetri Compounds having one cyano group such as carbonitrile, 1,3,5-pentanetricarbonitrile, pentafluoropropionitrile;

Marononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, azelanitrile, sebaconitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile , 2,2-Dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, trimethylsuccinonitrile, tetramethylsuccinonitrile, 3,3'-(ethylenedioxy) dipropionitrile, 3,3'-( Ethylenedithio) A compound having two cyano groups such as dipropionitrile;

Compounds having three cyano groups such as 1,2,3-tris (2-cyanoethoxy) propane and tris (2-cyanoethyl) amine;

Cyanate compounds such as methyl cyanate, ethyl cyanate, propyl cyanate, butyl cyanate, pentyl cyanate, hexyl cyanate, heptyl cyanate;

Methyl thiocyanate, ethyl thiocyanate, propyl thiocyanate, butyl thiocyanate, pentyl thiocyanate, hexyl thiocyanate, heptyl thiocyanate, methanesulfonyl cyanate, ethanesulfonyl cyanate, propanesulfonyl cyanate, butane sulfonyl cyanate, pentan sulfonyl cyanate, hexane sulfonyl cyanate , Heptane sulfonyl cyanide, methylsulfrosianidate, ethylsulfrosianidate, propylsulfrusianidate, butylsulfrosiocyanate, pentylsulfrusianidate, hexylsulfrusianidate, heptylsul Sulfur-containing compounds such as frocyanidate;

Cyanodimethylphosphine, cyanodimethylphosphine oxide, methyl cyanomethylphosphinate, methyl cyanomethyl phosphinate, dimethylphosphinic acid cyanide, dimethyl phosphite cyanide, dimethyl cyanophosphonate, dimethyl cyano phosphite, cyanomethyl methylphosphonate, methyl phosphon Phosphate-containing compounds such as cyanomethyl acid and cyanodimethyl phosphite;
And so on.

Of these
Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, crotononitrile, 3-methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, Azelanitrile, sebaconitrile, undecandinitrile, and dodecandinitrile are preferable from the viewpoint of improving storage characteristics, and cyano such as malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, azellanitrile, sebaconitrile, undecandinitrile, and dodecanenitrile A compound having two groups is more preferable.

As the compound having a cyano group, one type may be used alone, or two or more types may be used in any combination and ratio. The content of the compound having a cyanide group in the entire non-aqueous electrolyte solution of the present embodiment is not particularly limited and is arbitrary. With respect to the non-aqueous electrolyte solution of the present embodiment, it is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, and more. , Usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within the above range, improvement effects such as input / output characteristics, charge / discharge rate characteristics, cycle characteristics, and high temperature storage characteristics tend to be exhibited.

<1-4-5. Diisocianato compound>
As the diisocyanate compound, a compound having a nitrogen atom only in the isocyanato group and two isocyanato groups in the molecule and represented by the following general formula (4) is preferable.

In the above general formula (4), X is an organic group having a cyclic structure and having 1 or more and 15 or less carbon atoms. The carbon number of X is usually 2 or more, preferably 3 or more, more preferably 4 or more, and usually 14 or less, preferably 12 or less, more preferably 10 or less, still more preferably 8 or less.

In the above general formula (4), X is particularly preferably an organic group having 4 to 15 carbon atoms and having one or more cycloalkylene groups having 4 to 6 carbon atoms or aromatic hydrocarbon groups. At this time, the hydrogen atom on the cycloalkylene group may be substituted with a methyl group or an ethyl group. Since the diisocyanate compound having the cyclic structure is sterically bulky and therefore a molecule, side reactions on the positive electrode are unlikely to occur, and as a result, the cycle characteristics and the high temperature storage characteristics can be improved. Here, the bonding site of the group bonded to the cycloalkylene group or the aromatic hydrocarbon group is not particularly limited and may be any of the meta position, the para position and the ortho position, but the meta position or the para position is the film. It is preferable that the cross-linking distance is appropriate because it is advantageous for lithium ion conductivity and tends to reduce the resistance. Further, among the cycloalkylene groups, a cyclopentylene group or a cyclohexylene group is preferable from the viewpoint that the diisocyanate compound itself is unlikely to cause a side reaction, and the resistance is easily reduced due to the influence of molecular motility. Therefore, the cyclohexylene group. Is more preferable.

Further, it is preferable to have an alkylene group having 1 to 3 carbon atoms between the cycloalkylene group or the aromatic hydrocarbon group and the isocyanate group. Since having an alkylene group makes it three-dimensionally bulky, side reactions on the positive electrode tend to be less likely to occur. Further, when the alkylene group has 1 to 3 carbon atoms, the occupancy ratio of the isocyanate group to the total molecular weight can be kept relatively large, so that the compounding effect of the compound represented by the general formula (4) is remarkably exhibited. It tends to be easy to do.

The molecular weight of the diisocyanate compound represented by the general formula (4) is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is usually 80 or more, preferably 115 or more, more preferably 170 or more, and usually 300 or less, preferably 230 or less. Within this range, the solubility of the diisocyanate compound in a non-aqueous electrolyte solution tends to be easily ensured.

Specific examples of the diisocyanate compound include, for example,
1,2-Diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, 1,2 -Bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-2,4' Cycloalkane ring-containing diisocyanates such as −diisocyanate, dicyclohexylmethane-3,3′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate;
1,2-phenylenediisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, tolylen-2,3-diisocyanate, tolylen-2,4-diisocyanate, tolylen-2,5-diisocyanate, tolylen-2,6 -Diisocyanate, Trilen-3,4-Diisocyanate, Trilen-3,5-Diisocyanate, 1,2-bis (isocyanatomethyl) benzene, 1,3-bis (isocyanatomethyl) benzene, 1,4-bis (isocyanatomethyl) Natomethyl) benzene, 2,4-diisocyanatobiphenyl, 2,6-diisocyanatobiphenyl, 2,2'-diisocyanatobiphenyl, 3,3'-diisocyanatobiphenyl, 4,4'-diisocyanato- 2-Methylbiphenyl, 4,4'-diisocyanato-3-methylbiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 4,4'-diisocyanato diphenylmethane, 4,4'-diisocyanato-2 -Methyldiphenylmethane, 4,4'-diisocyanato-3-methyldiphenylmethane, 4,4'-diisocyanato-3,3'-dimethyldiphenylmethane, 1,5-diisocyanatonaphthalene, 1,8-diisocyanatonaphthalene, 2 , 3-Diisocyanatonaphthalene, 1,5-bis (isocyanatomethyl) naphthalene, 1,8-bis (isocyanatomethyl) naphthalene, 2,3-bis (isocyanatomethyl) naphthalene and other aromatic ring-containing diisocyanates ;
And so on.

Among these, 1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane , 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-phenylenediocyanate, 1,3-phenylenediocyanate , 1,4-phenylenediocyanate, 1,2-bis (isocyanatomethyl) benzene, 1,3-bis (isocyanatomethyl) benzene, 1,4-bis (isocyanatomethyl) benzene, 2,4-diisosia Natobiphenyl and 2,6-diisocyanatobiphenyl are preferable because a denser complex film is likely to be formed on the negative electrode, and as a result, battery durability tends to be improved.

Among these, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, 1,2-bis (isocyanato) Methyl) benzene, 1,3-bis (isocyanatomethyl) benzene, and 1,4-bis (isocyanatomethyl) benzene are likely to form a film advantageous for lithium ion conductivity on the negative electrode due to their molecular symmetry. As a result, the battery characteristics tend to be further improved, which is more preferable.

Further, as the above-mentioned diisocyanate compound, one kind may be used alone, or two or more kinds may be used in any combination and ratio.

The content of the diisocyanate compound is not particularly limited and is arbitrary, but is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0, based on the non-aqueous electrolyte solution of the present embodiment. .1% by mass or more, more preferably 0.3% by mass or more, and usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less. When the content of the diisocyanate compound is within the above range, the durability such as cycle and storage tends to be improved.

The method for producing the diisocyanate compound is not particularly limited, and a known method can be arbitrarily selected for production. Moreover, you may use a commercially available product.

<2-4-6. Carboxylic acid anhydride>
As the carboxylic acid anhydride, a compound represented by the following general formula (5) is preferable. The method for producing the carboxylic acid anhydride is not particularly limited, and a known method can be arbitrarily selected for production.

(In the general formula (5), R ¹ and R ² each independently represent a hydrocarbon group having 1 to 15 carbon atoms which may have a substituent. R ¹ and R ² are bonded to each other. May form an annular structure.)

The types of R ¹ and R ² are not particularly limited as long as they are monovalent hydrocarbon groups. For example, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or may be a bond of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain an unsaturated bond (carbon-carbon double bond or carbon-carbon triple bond). Further, the aliphatic hydrocarbon group may be chain-like or cyclic, and in the case of chain-like, it may be linear or branched-chain. Furthermore, the chain and the ring may be combined. In addition, R ¹ and R ² may be the same as each other or may be different from each other.

Further, when R ¹ and R ² are bonded to each other to form a cyclic structure, the hydrocarbon group formed by bonding R ¹ and R ² to each other is divalent. The type of divalent hydrocarbon group is not particularly limited. That is, it may be an aliphatic group or an aromatic group, or may be a combination of an aliphatic group and an aromatic group. In the case of an aliphatic group, it may be a saturated group or an unsaturated group. Further, it may be a chain group or a cyclic group, and in the case of a chain group, it may be a linear group or a branched chain group. Further, a chain group and a cyclic group may be bonded.

When the hydrocarbon groups of R ¹ and R ² have a substituent, the type of the substituent is not particularly limited. Specific examples thereof include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, and among them, fluorine atom is preferable. Further, examples of the substituent other than the halogen atom include a substituent having a functional group such as an ester group, a cyano group, a carbonyl group and an ether group, and among them, a cyano group and a carbonyl group are preferable. The hydrocarbon groups of R ¹ and R ² may have only one of these substituents, or may have two or more of them. When having two or more substituents, the substituents may be the same or different from each other.

The carbon number of each hydrocarbon group of R ¹ and R ² is usually 1 or more, and is usually 15 or less, preferably 12 or less, more preferably 10 or less, and further preferably 9 or less. When R ¹ and R ² are bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms of the divalent hydrocarbon group is usually 2 or more, and usually 15 or less, preferably 15 or less. It is 13 or less, more preferably 10 or less, still more preferably 8 or less. When the hydrocarbon groups of R ¹ and R ² have a substituent containing a carbon atom, it is preferable that the total number of carbon atoms of R ¹ and R ² including the substituent satisfies the above range.

Next, a specific example of the carboxylic acid anhydride represented by the general formula (5) will be described. In the following examples, the "related material" means a carboxylic acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure, for example, a plurality of carboxylic acid anhydrides. Dimers, trimerics, tetramers, etc. consisting of, or isostructural heterogeneous ones having the same number of carbon atoms but having a branched chain, and different sites where the substituents bind to carboxylic acid anhydrides. Things etc. can be mentioned.

First, specific examples of carboxylic acid anhydrides in which R ¹ and R ² are the same are given below.

Specific examples of carboxylic acid anhydrides in which R ¹ and R ² are chain alkyl groups include acetic anhydride, propionic anhydride, butanoic anhydride, 2-methylpropionic anhydride, and 2,2-dimethylpropionic acid. Anhydrous, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2,2-dimethylbutanoic anhydride, 2,3-dimethylbutanoic anhydride, 3,3-dimethylbutanoic anhydride, 2,2 , 3-trimethylbutanoic anhydride, 2,3,3-trimethylbutanoic anhydride, 2,2,3,3-tetramethylbutanoic anhydride, 2-ethylbutanoic anhydride, etc., and their analogs, etc. Can be mentioned.

Specific examples of the carboxylic acid anhydride in which R ¹ and R ² are cyclic alkyl groups include cyclopropanecarboxylic acid anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, and their analogs. Be done.

Specific examples of carboxylic acid anhydrides in which R ¹ and R ² are alkenyl groups include acrylate anhydride, 2-methyl acrylate anhydride, 3-methyl acrylate anhydride, and 2,3-dimethyl acrylate anhydride. , 3,3-Dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3 , 3-Diphenylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-butenoic anhydride , 2-Methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentene Examples thereof include carboxylic acid anhydride, 3-cyclopentenecarboxylic acid anhydride, 4-cyclopentenecarboxylic acid anhydride and the like, and analogs thereof.

Specific examples of carboxylic acid anhydrides in which R ¹ and R ² are alkynyl groups include propic acid anhydride, 3-phenylpropic acid anhydride, 2-butynic acid anhydride, 2-pentyne anhydride, and 3-butyne. Examples thereof include acid anhydrides, 3-pentanoic anhydrides, 4-pentanoic anhydrides and the like, and their analogs.

Specific examples of carboxylic acid anhydrides in which R ¹ and R ² are aryl groups include benzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-ethyl benzoic acid anhydride, and 4-tert-butyl benzoic acid anhydride. , 2-Methylbenzoic acid anhydride, 2,4,6-trimethylbenzoic acid anhydride, 1-naphthalenecarboxylic acid anhydride, 2-naphthalenecarboxylic acid anhydride and the like, and their analogs and the like.

Further, as an example of a carboxylic acid anhydride in which R ¹ and R ² are substituted with a halogen atom, an example of a carboxylic acid anhydride in which R ¹ and R ² are mainly substituted with a fluorine atom is given below, and some of these fluorine atoms or Carboxylic acid anhydrides obtained by substituting all of them with chlorine atoms, bromine atoms and iodine atoms are also included in the exemplary compounds.

Examples of carboxylic acid anhydrides in which R ¹ and R ² are chain alkyl groups substituted with halogen atoms include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, and 2-fluoropropionic anhydride. , 2,2-Difluoropropionic acid anhydride, 2,3-difluoropropionic acid anhydride, 2,2,3-trifluoropropionic acid anhydride, 2,3,3-trifluoropropionic acid anhydride, 2,2 , 3,3-Tetrapropionic acid anhydride, 2,3,3,3-tetrapropionic acid anhydride, 3-fluoropropionic acid anhydride, 3,3-difluoropropionic acid anhydride, 3,3,3-tri Fluoropropionic anhydride, perfluoropropionic anhydride and the like, and their analogs and the like can be mentioned.

Examples of carboxylic acid anhydrides in which R ¹ and R ² are cyclic alkyl groups substituted with halogen atoms include 2-fluorocyclopentanecarboxylic acid anhydride, 3-fluorocyclopentanecarboxylic acid anhydride, and 4-fluorocyclo. Examples thereof include pentancarboxylic acid anhydrides and their analogs.

Examples of carboxylic acid anhydrides in which R ¹ and R ² are alkenyl groups substituted with halogen atoms are 2-fluoroacrylic acid anhydride, 3-fluoroacrylic acid anhydride, and 2,3-difluoroacrylic acid anhydride. , 3,3-Difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2- (trifluoromethyl) acrylic anhydride, 3- (trifluoromethyl) acrylic anhydride, 2, 3-Bis (trifluoromethyl) acrylate anhydride, 2,3,3-tris (trifluoromethyl) acrylate anhydride, 2- (4-fluorophenyl) acrylate anhydride, 3- (4-fluorophenyl) ) Acrylic anhydride, 2,3-bis (4-fluorophenyl) acrylic anhydride, 3,3-bis (4-fluorophenyl) acrylic anhydride, 2-fluoro-3-butenoic anhydride, 2 , 2-Difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3 , 4-Trifluoro-3-butenoic anhydride and the like, and their analogs and the like.

Examples of carboxylic acid anhydrides in which R ¹ and R ² are alkynyl groups substituted with halogen atoms include 3-fluoro-2-propic anhydride and 3- (4-fluorophenyl) -2-propic anhydride. , 3- (2,3,4,5,6-pentafluorophenyl) -2-propic anhydride, 4-fluoro-2-butanoic anhydride, 4,4-difluoro-2-butanoic anhydride , 4,4,4-Trifluoro-2-butylic anhydride and the like, and their analogs and the like.

Examples of carboxylic acid anhydrides in which R ¹ and R ² are aryl groups substituted with halogen atoms include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, Examples thereof include 4-trifluoromethylbenzoic anhydride and the like, and their analogs and the like.

Examples of carboxylic acid anhydrides in which R ¹ and R ² have substituents having functional groups such as esters, nitriles, ketones, and ethers include methoxygenic acid anhydrides, ethoxysilic acid anhydrides, and methyl oxalic acid anhydrides. , Ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, etc. , And their relatives and the like.

Subsequently, specific examples of carboxylic acid anhydrides in which R ¹ and R ² are different from each other will be given below.

As R ¹ and R ² , the above-mentioned examples and all combinations of their analogs can be considered, and typical examples are given below.

Examples of combinations of chain alkyl groups include propionic acetate anhydride, butanoic anhydride, butane propionic anhydride, 2-methylpropionic anhydride,
And so on.

Examples of the combination of the chain alkyl group and the cyclic alkyl group include cyclopentanoic acid anhydride, cyclohexaneic acid acetate anhydride, propionic anhydride, and the like.

Examples of the combination of the chain alkyl group and the alkenyl group include acrylic anhydride, 3-methylacrylic acetate, 3-butenoic acid anhydride, propionic anhydride and the like.

Examples of combinations of chain alkyl groups and alkynyl groups include propicic anhydride, 2-butynic acetate anhydride, 3-butynic acetate anhydride, 3-phenylpropic anhydride acetate, and propionic propionate anhydride. Things, etc. can be mentioned.

Examples of the combination of the chain alkyl group and the aryl group include benzoic acid anhydride, 4-methylbenzoic acid anhydride, 1-naphthalenecarboxylic acid anhydride, propionic anhydride and the like.

Examples of combinations of a chain alkyl group and a hydrocarbon group having a functional group include fluoroacetic acid anhydride, trifluoroacetic acid anhydride, 4-fluorobenzoic acid anhydride, fluoropropionic acid anhydride, and alkyl acetate. Examples thereof include oxalic acid anhydride, 2-cyanoacetic acid anhydride, 2-oxopropionic acid acetate anhydride, methoxyacetylacetic acid anhydride, methoxypropionic acid anhydride and the like.

Examples of combinations of cyclic alkyl groups include cyclopentanoic acid cyclohexaneic anhydride and the like.

Examples of combinations of cyclic alkyl groups and alkenyl groups include cyclopentanoic anhydride, 3-methylacrylate cyclopentanoic anhydride, 3-butenoic cyclopentanoic anhydride, cyclohexaneic anhydride, etc. Can be mentioned.

Examples of the combination of the cyclic alkyl group and the alkynyl group include cyclopentanoic anhydride, 2-butynate cyclopentanoic anhydride, cyclohexaneic anhydride, and the like.

Examples of the combination of the cyclic alkyl group and the aryl group include cyclopentanoic anhydride of benzoate, cyclopentanoic anhydride of 4-methylbenzoate, cyclohexaneic anhydride of benzoate, and the like.

Examples of combinations of cyclic alkyl groups and hydrocarbon groups with functional groups include cyclopentanoic anhydride, cyclopentanoic acid trifluoroacetic anhydride, cyclopentanoic 2-cyanoacetic anhydride, and methoxyacetic anhydride. Anhydride, cyclohexanoic acid fluoroacetic anhydride, and the like can be mentioned.

Examples of combinations of alkenyl groups include 2-methylacrylic anhydride of acrylate, 3-methylacrylic anhydride of acrylate, 3-butenoic anhydride of acrylate, and 3-methylacrylic anhydride of 2-methylacrylate. Things, etc. can be mentioned.

Examples of the combination of the alkenyl group and the alkynyl group include acrylic acid propicic anhydride, acrylic acid 2-butynic anhydride, 2-methylacrylic acid propicic anhydride, and the like.

Examples of the combination of the alkenyl group and the aryl group include acrylic acid benzoic acid anhydride, acrylic acid 4-methylbenzoic acid anhydride, 2-methylacrylic acid benzoic acid anhydride, and the like.

Examples of combinations of an alkenyl group and a hydrocarbon group having a functional group include fluoroacetic acid anhydride, trifluoroacetic acid anhydride, 2-cyanoacetic acid anhydride, methoxyacetic acid anhydride, 2-. Examples thereof include methyl acrylate fluoroacetic acid anhydride.

Examples of combinations of alkynyl groups include propanoic acid 2-butynic anhydride, propic acid 3-butynic anhydride, 2-butynic acid 3-butynic anhydride, and the like.

Examples of the combination of the alkynyl group and the aryl group include benzoic acid propicic anhydride, 4-methylbenzoic acid propicic anhydride, benzoic acid 2-butynic anhydride, and the like.

Examples of combinations of an alkynyl group and a hydrocarbon group having a functional group include fluoroacetic anhydride, trifluoroacetic anhydride, 2-cyanoacetic anhydride, 2-cyanoacetic anhydride, methoxyacetic anhydride, 2-. Fluoroacetic anhydride, butynate, and the like can be mentioned.

Examples of combinations of aryl groups include 4-methylbenzoic acid anhydride, 1-naphthalenecarboxylic acid anhydride, 4-methylbenzoic acid 1-naphthalenecarboxylic acid anhydride, and the like.

Examples of combinations of an aryl group and a hydrocarbon group having a functional group include fluoroacetic anhydride of benzoate, trifluoroacetic anhydride of benzoate, 2-cyanoacetate anhydride of benzoate, methoxyacetic anhydride of benzoate, 4- Fluoroacetic anhydride of methylbenzoate, and the like can be mentioned.

Examples of combinations of hydrocarbon groups having functional groups include trifluoroacetic acid anhydride, fluoroacetic acid 2-cyanoacetate anhydride, fluoroacetic acid methoxyacetic acid anhydride, trifluoroacetic acid 2-cyanoacetate anhydride, and the like. Can be mentioned.

Of the carboxylic acid anhydrides forming the above chain structure, preferably
Acetic anhydride, propionic acid anhydride, 2-methylpropionic acid anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, etc., acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride , 2,3-dimethylacrylic acid anhydride, 3,3-dimethylacrylic acid anhydride, 3-butenoic acid anhydride, 2-methyl-3-butenoic acid anhydride, propic acid anhydride, 2-butanoic acid anhydride , Anhydrous benzoate, 2-Methyl benzoate anhydride, 4-Methyl benzoate anhydride, 4-tert-butyl benzoic acid anhydride, trifluoroacetate anhydride, 3,3,3-trifluoropropionic acid anhydride , 2- (Trifluoromethyl) acrylate anhydride, 2- (4-fluorophenyl) acrylate anhydride, 4-fluorobenzoic acid anhydride, 2,3,4,5,6-pentafluorobenzoic acid anhydride , Methoxysilic anhydride, ethoxysilic anhydride,
And more preferably
Acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride, benzoic acid anhydride, 2-methylbenzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-tert-butyl benzoic acid anhydride The product, 4-fluorobenzoic acid anhydride, 2,3,4,5,6-pentafluorobenzoic acid anhydride, methoxycirate anhydride, ethoxygeic acid anhydride.

These carboxylic acid anhydrides appropriately form bonds with lithium oxalate salts to form a film having excellent durability, thereby improving charge / discharge rate characteristics, input / output characteristics, and impedance characteristics especially after the durability test. It is preferable from the viewpoint that it can be discharged.

Subsequently, specific examples of the carboxylic acid anhydride in which R ¹ and R ² are bonded to each other to form a cyclic structure will be given below.

First, specific examples of the carboxylic acid anhydride in which R ¹ and R ² are bonded to each other to form a 5-membered ring structure include succinic anhydride, 4-methylsuccinic anhydride, and 4,4-dimethylsuccinic acid. Anhydride, 4,5-dimethylsuccinic anhydride, 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5 − Divinyl succinic anhydride, 4-phenylsuccinic anhydride, 4,5-diphenylsuccinic anhydride, 4,4-diphenylsuccinic anhydride, citraconic acid anhydride, maleic anhydride, 4-methylmaleic anhydride , 4,5-dimethylmaleic anhydride, 4-phenylmaleic anhydride, 4,5-diphenylmaleic anhydride, itaconic acid anhydride, 5-methylitaconic acid anhydride, 5,5-dimethylitaconic acid Anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride and the like, and their analogs and the like can be mentioned.

Specific examples of the carboxylic acid anhydride in which R ¹ and R ² are bonded to each other to form a 6-membered ring structure include cyclohexane-1,2-dicarboxylic acid anhydride and 4-cyclohexene-1,2-dicarboxylic acid. Examples thereof include acid anhydrides, glutaric acid anhydrides, and their analogs.

Specific examples of the carboxylic acid anhydride in which R ¹ and R ² are bonded to each other to form another cyclic structure are 5-norbornene-2,3-dicarboxylic acid anhydride and cyclopentanetetracarboxylic dianhydride. Examples thereof include substances, pyromellitic anhydrides, diglycolic acid anhydrides, and their analogs.

Specific examples of carboxylic acid anhydrides in which R ¹ and R ² are bonded to each other to form a cyclic structure and are substituted with halogen atoms include 4-fluorosuccinic anhydride and 4,4-difluorosuccinic anhydride. , 4,5-Difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, 4,4,5,5-tetrafluorosuccinic anhydride, 4-fluoromaleic anhydride, 4, Examples thereof include 5-difluoromaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and their analogs.

Of the carboxylic acid anhydrides in which R ¹ and R ² are bonded, preferably
Succinic anhydride, 4-methylsuccinic anhydride, 4-vinylsuccinic anhydride, 4-phenylsuccinic anhydride, citraconic acid anhydride, maleic anhydride, 4-methylmaleic anhydride, 4-phenylmaleic anhydride , Itaconic Acid Anhydride, 5-Methylitaconic Acid Anhydride, Gluteric Acid Anhydride, Phthalic Anhydride, Cyclohexane-1,2-Dicarboxylic Acid Anhydride, 5-Norbornen-2,3-dicarboxylic Acid Anhydride, Cyclopentanetetra Carboxydic dianhydride, pyromellitic anhydride, 4-fluorosuccinic anhydride, 4-fluoromaleic anhydride, 5-fluoroitaconic acid anhydride,
And more preferably
Succinic anhydride, 4-methylsuccinic anhydride, 4-vinylsuccinic anhydride, citraconic acid anhydride, cyclohexane-1,2-dicarboxylic acid anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetra It is a carboxylic acid dianhydride, a pyromellitic anhydride, and a 4-fluorosuccinic anhydride. These compounds are preferable because they appropriately form a bond with the lithium oxalate salt to form a film having excellent durability, and thus the capacity retention rate after the durability test is improved.

The molecular weight of the carboxylic acid anhydride is not limited and is arbitrary, but is usually 90 or more, preferably 95 or more, while usually 300 or less, preferably 200 or less. When the molecular weight of the carboxylic acid anhydride is within the above range, the increase in viscosity of the non-aqueous electrolyte solution is suppressed, the film density is optimized, and the durability tends to be appropriately improved.

Further, the method for producing the carboxylic acid anhydride is not particularly limited, and a known method can be arbitrarily selected for production. As the carboxylic acid anhydride described above, any one of them may be used alone or two or more of them may be used in any combination and ratio in the non-aqueous electrolyte solution of the present embodiment.

The content of the carboxylic acid anhydride in the non-aqueous electrolyte solution of the present embodiment is not particularly limited and is arbitrary, but is usually 0.01% by mass or more with respect to the non-aqueous electrolyte solution of the present embodiment. It is preferably contained in a concentration of 0.1% by mass or more, usually 5% by mass or less, preferably 3% by mass or less. When the content of the carboxylic acid anhydride is within the above range, the effect of improving the cycle characteristics is likely to be exhibited, the reactivity is preferable, and the battery characteristics tend to be improved.

<2-4-7. Overcharge inhibitor ＞
In the non-aqueous electrolyte solution of the present embodiment, an overcharge inhibitor can be used in order to effectively suppress the explosion and ignition of the lithium battery when the lithium battery or the like is in a state of overcharging or the like.

Examples of the overcharge inhibitor include biphenyl, alkylbiphenyl, terphenyl, a partially hydride of terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl. Aromatic compounds such as -3-phenylindan; partially fluorinated compounds of the above aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoro Fluoro-containing anisole compounds such as anisole, 2,6-difluoroanisole and 3,5-difluoroanisole; 3-propylphenylacetate, 2-ethylphenylacetate, benzylphenylacetate, methylphenylacetate, benzylacetate, phenethylphenylacetate and the like. Aromatic acetates; Examples thereof include aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate. Among them, biphenyl, alkylbiphenyl, terphenyl, partially hydride of terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindan. , 3-propylphenylacetate, 2-ethylphenylacetate, benzylphenylacetate, methylphenylacetate, benzylacetate, phenethylphenylacetate, diphenylcarbonate, methylphenylcarbonate are preferred. One of these may be used alone, or two or more thereof may be used in any combination and ratio. When two or more kinds are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, a partially hydride of biphenyl, alkylbiphenyl, tarphenyl, or tarphenyl, cyclohexylbenzene, t-butylbenzene, It is the overcharge prevention property and high temperature that at least one selected from oxygen-free aromatic compounds such as t-amylbenzene and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran are used in combination. It is preferable from the viewpoint of the balance of storage characteristics.

The content of the overcharge inhibitor is not particularly limited and is arbitrary. The content of the overcharge inhibitor is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.% by mass in 100% by mass of the non-aqueous electrolyte solution. It is 5% by mass or more, and usually 5% by mass or less, preferably 4.8% by mass or less, and more preferably 4.5% by mass or less. Within this range, the effect of the overcharge inhibitor is likely to be sufficiently exhibited, and the battery characteristics such as high temperature storage characteristics tend to be improved.

<2-4-8. Other auxiliaries>
Other known auxiliaries can be used for the non-aqueous electrolyte solution of the present embodiment. Other auxiliaries include
Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate;
Methyl-2-propynyl oxalate, ethyl-2-propynyl oxalate, bis (2-propynyl) oxalate, 2-propynyl acetate, 2-propynylformate, 2-propynyl methacrylate, di (2-propynyl) glutarate, Methyl-2-propynyl carbonate, ethyl-2-propynyl carbonate, bis (2-propynyl) carbonate, 2-butin-1,4-diyl-dimethanesulfonate, 2-butin-1,4-diyl-diethanesulfonate, 2-Butin-1,4-diyl-diformate, 2-butin-1,4-diyl-diacetate, 2-butine-1,4-diyl-dipropionate, 4-hexadiyne-1,6-diyl-dimethanesulfonate , 2-Propinyl-methanesulfonate, 1-methyl-2-propynyl-methanesulfonate, 1,1-dimethyl-2-propynyl-methanesulfonate, 2-propynyl-ethanesulfonate, 2-propynyl-vinylsulfonate, 2-propynyl- Triple bond-containing compounds such as 2- (diethoxyphosphoryl) acetate, 1-methyl-2-propynyl-2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propynyl-2- (diethoxyphosphoryl) acetate ;
Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane;
Ethylene sulfide, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methane sulfonate, ethyl methane sulfonate, busulfane, sulfolene, ethylene sulfate, vinylene sulfate, diphenyl sulfone, N, N-dimethylmethane sulfonamide, N, N- Sulfur-containing compounds such as diethylmethanesulfonamide, trimethylsilyl methylsulfate, trimethylsilyl ethylsulfate, 2-propynyl-trimethylsilylsulfate;
2-Isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2-isocyanatoethoxy) ethyl acrylate, 2- (2-isocyanatoethoxy) ethyl methacrylate, 2- (2) -Isocyanate ethoxy) Isocyanate compounds such as ethyl crotonate;
Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide;
Hydrocarbon compounds such as heptane, octane, nonane, decane, cycloheptane;
Fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, 1,2-bis (trifluoromethyl) benzene, 1,3-bis (trifluoromethyl) benzene, 1,4-bis (trifluoromethyl) benzene, Fluorine-containing aromatic compounds such as pentafluorophenylmethane sulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, and methyl pentafluorophenyl carbonate;
Tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris phosphate (trimethylsilyl), tris phosphate (trimethoxysilyl), dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyalumino Silane compounds such as xytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titanium tetrakis (trimethylsiloxide), titanium tetrakis (triethylsiloxide);
2-Propinyl 2- (methanesulfonyloxy) propionic acid, 2-methyl 2- (methanesulfonyloxy) propionic acid, 2-ethyl 2- (methanesulfonyloxy) propionic acid, 2-propynyl methanesulfonyloxyacetic acid, methanesulfonyloxy Ester compounds such as 2-methyl acetate and 2-ethyl methanesulfonyloxy acetate;
Lithium Ethyl Methyloxycarbonylphosphonate, Lithium Ethyl Ethyloxycarbonylphosphonate, Lithium Ethyl-2-Propinyloxycarbonylphosphonate, Lithium Ethyl-1-Methyl-2-Propinyloxycarbonylphosphonate, Lithium Ethyl-1,1-dimethyl-2-Propinyl Lithium salts such as oxycarbonylphosphonate, lithium methylsulfate, lithium ethylsulfate;
And so on. One of these may be used alone, or two or more thereof may be used in any combination and ratio. By adding these auxiliaries, the capacity retention characteristics and cycle characteristics after high temperature storage tend to be improved.

The content of the other auxiliary agent is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The content of the other auxiliary agent is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and usually, in 100% by mass of the non-aqueous electrolyte solution. It is 5% by mass or less, preferably 3% by mass or less, and more preferably 1% by mass or less. Within this range, the effect of containing other auxiliaries is likely to be sufficiently exhibited, and battery characteristics such as high load discharge characteristics tend to be improved.

The non-aqueous electrolyte solution described above includes those existing inside the non-aqueous electrolyte battery. Specifically, the components of the non-aqueous electrolyte solution such as lithium salt, solvent, and auxiliary agent are separately synthesized, and the non-aqueous electrolyte solution is prepared from the substantially isolated one, and the method described below is used. Non-aqueous electrolyte solution obtained by injecting liquid into a separately assembled battery When it is a non-aqueous electrolyte solution in a battery, or when the components of the non-aqueous electrolyte solution of the present embodiment are individually put in the battery, the battery When the same composition as the non-aqueous electrolyte solution of the present embodiment is obtained by mixing in the battery, the compound constituting the non-aqueous electrolyte solution of the present embodiment is further generated in the non-aqueous electrolyte battery to generate the present invention. The case where the same composition as the non-aqueous electrolyte solution of the embodiment is obtained is also included.

<3. Power storage device using non-aqueous electrolyte solution>
The power storage device using the non-aqueous electrolyte solution of the present embodiment has a positive electrode, a negative electrode, and a non-aqueous solvent as an electrolyte in which the lithium salt represented by the above-mentioned general formula LiBFn (NCO) _4-n is dissolved. It is characterized by being provided with an aqueous electrolytic solution.

The power storage device using the non-aqueous electrolyte solution of the present embodiment includes a lithium battery as a non-aqueous electrolyte secondary battery, a polyvalent cation battery, a metal air secondary battery, and a secondary battery using an s-block metal described later. , Lithium ion capacitors are preferred, lithium batteries and lithium ion capacitors are more preferred, and lithium batteries are even more preferred.

It is also preferable that the non-aqueous electrolyte solution used in these power storage devices is a so-called gel electrolyte that is pseudo-solidified with a polymer, a filler, or the like. Further, the lithium salt represented by the above-mentioned general formula LiBFn (NCO) _4-n can also be used as an electrolyte salt of a solid electrolyte.

<3-1. Lithium battery ＞
The lithium battery using the non-aqueous electrolyte solution of the present embodiment is provided on the current collector and the positive electrode having a positive electrode active material layer provided on the current collector, and on the current collector and the current collector. It includes a negative electrode having a negative electrode active material layer and capable of occluding and releasing ions, and the non-aqueous electrolyte solution of the present embodiment described above. The lithium battery in the present embodiment is a general term for a lithium primary battery and a lithium secondary battery.

<3-1-1. Battery configuration>
The lithium battery of the present embodiment is the same as the conventionally known lithium battery except for the above-described non-aqueous electrolyte solution of the present embodiment. Usually, the positive electrode and the negative electrode are laminated via a porous membrane (separator) impregnated with the non-aqueous electrolyte solution of the present embodiment, and these are housed in a case (exterior body). Therefore, the shape of the lithium battery of the present embodiment is not particularly limited and may be arbitrary, for example, a cylindrical type, a square shape, a laminated type, a coin type, a large size, or the like.

<3-1-2. Non-aqueous electrolyte>
As the non-aqueous electrolyte solution, the non-aqueous electrolyte solution of the present embodiment described above is used. In addition, other non-aqueous electrolytic solutions may be further added to the non-aqueous electrolytic solution as long as the gist of the present invention is not deviated.

<3-1-3. Negative electrode ＞
The negative electrode has a negative electrode active material layer on the current collector, and the negative electrode active material layer contains a negative electrode active material. Hereinafter, the negative electrode active material will be described.
The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples thereof include carbonaceous materials, metal alloy materials, lithium-containing metal composite oxide materials, and the like. One of these may be used alone, or two or more thereof may be used in any combination and ratio.

<3-1-3-1. Carbon material>
The carbonaceous material used as the negative electrode active material is not particularly limited, but one selected from the following (a) to (d) is preferable because it has a good balance between initial irreversible capacitance and high current density charge / discharge characteristics. Further, as the carbonaceous materials (a) to (d), one kind may be used alone, or two or more kinds may be used in any combination and ratio.

(A) Natural graphite (B) Carbonaceous material obtained by heat-treating artificial carbonaceous material and artificial graphite material at least once in the range of 400 to 3200 ° C. (C) Negative electrode active material layer has at least two different crystalline properties. Carbon material consisting of carbonaceous material and / or having an interface in which different crystalline carbonaceous materials are in contact (d) The negative electrode active material layer is composed of at least two or more kinds of carbonic material having different orientations / Or a carbonaceous material having an interface where the carbonaceous materials of different orientations are in contact with each other.

Specific examples of the artificial carbonic material and the artificial graphite material in (a) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or those obtained by oxidizing these pitches; Needle coke, pitch coke and partially graphitized carbon material; thermal decomposition products of organic substances such as furnace black, acetylene black and pitch carbon fibers; carbonizable organic substances and their carbonized substances; carbonizable organic substances are benzene , A solution dissolved in a low molecular weight organic solvent such as toluene, xylene, quinoline, n-hexane, and carbides thereof; and the like.

<3-1-3-2. Composition, physical properties, preparation method of carbonic negative electrode ＞
In addition, all of the above carbonaceous materials (a) to (d) are conventionally known, their manufacturing methods are well known to those skilled in the art, and these commercially available products can also be purchased. Regarding the properties of the carbonaceous material, the negative electrode containing the carbonaceous material, the electrode conversion method, the current collector, and the lithium battery, any one or more of the following items (1) to (13) are satisfied at the same time. It is desirable to have.

(1) X-ray parameters The d value (interlayer distance) of the lattice planes (002 planes) obtained by X-ray diffraction of carbonaceous materials is usually 0.335 to 0.340 nm, particularly 0.335. It is preferably about 0.338 nm, particularly 0.335 to 0.337 nm. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is usually 1.0 nm or more, preferably 1.5 nm or more, and particularly preferably 2 nm or more.

(2) Volume-based average particle diameter As for the volume-based average particle diameter of the carbonaceous material, the volume-based average particle diameter (median diameter) obtained by the laser diffraction / scattering method is usually 1 μm or more, preferably 3 μm or more. It is more preferably 5 μm or more, particularly preferably 7 μm or more, and usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 25 μm or less.

The volume-based average particle size is measured by a laser diffraction / scattering method in which a carbonaceous material powder is dispersed in a 0.2% by mass aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant. This is performed using a particle size distribution meter (LA-700 manufactured by HORIBA, Ltd.). The median diameter obtained by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

(3) Raman R value, Raman half-price range The Raman R value of a carbonaceous material is usually 0.01 or more, preferably 0.03 or more, preferably 0.03 or more, as measured by an argon ion laser Raman spectroscopy method. 1 or more is more preferable, and usually 1.5 or less, 1.2 or less is preferable, 1 or less is further preferable, and 0.5 or less is particularly preferable.

When the Raman R value is within the above range, the crystallinity of the particle surface is in an appropriate range, the decrease of sites where Li enters between layers with charging and discharging can be suppressed, and the charge acceptability tends to be difficult to decrease. .. Further, when the negative electrode forming material (slurry) described later is applied to the current collector and then pressed to increase the density of the negative electrode, the load characteristics of the lithium battery or the like are less likely to deteriorate. Furthermore, it is less likely to cause a decrease in efficiency and an increase in gas generation.

The Raman half width around 1580 cm ^{-1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ^-1 or more, preferably 15 cm ^-1 or more, and usually 100 cm ^-1 or less, 80 cm ^-1 or less. Preferably, 60 cm ^-1 or less is more preferable, and 40 cm ^-1 or less is particularly preferable.

When the Raman half-value width is within the above range, the crystallinity of the particle surface becomes an appropriate range, the decrease of sites where Li enters between layers with charging and discharging can be suppressed, and the charge acceptability is less likely to decrease. Further, when the negative electrode is increased in density by applying the negative electrode forming material to the current collector and then pressing the current collector, the load characteristics of the lithium battery and the like are less likely to be deteriorated. Furthermore, it is less likely to cause a decrease in efficiency and an increase in gas generation.

The Raman spectrum is measured by using a Raman spectroscope (Raman spectroscope manufactured by Nippon Spectroscopy Co., Ltd.), the sample is naturally dropped into the measurement cell and filled, and the surface of the sample in the cell is irradiated with an argon ion laser beam. This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity IA of a peak PA around 1580 cm ^-1, and measuring the intensity IB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IB / IA) . The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material in the present specification. In addition, the half width of the peak PA near 1580 cm ^-1 of the obtained Raman spectrum is measured, and this is defined as the Raman half width of the carbonaceous material in the present specification.

The Raman measurement conditions described above are as follows.
-Argon ion laser wavelength: 514.5 nm
-Laser power on the sample: 15-25 mW
・ Resolution: 10 to 20 cm ^-1
-Measurement range: 1100 cm ^{-1 to} 1730 cm ^-1
・ Raman R value, Raman half width analysis: Background processing ・ Smoothing processing: Simple average, convolution 5 points

(4) BET Specific Surface Area The BET specific surface area of carbonaceous materials is such that the value of the specific surface area measured by the BET method is usually 0.1 m ² · g ^-1 or more, and 0.7 m ² · g ^-1 or more. Is preferable, 1.0 m ² · g ^-1 or more is more preferable, 1.5 m ² · g ^-1 or more is particularly preferable, and usually 100 m ² · g ^-1 or less, 25 m ² · g ^-1 or less. Preferably, 15 m ² · g ^-1 or less is more preferable, and 10 m ² · g ^-1 or less is particularly preferable.

When the value of the BET specific surface area is within the above range, the acceptability of cations such as lithium during charging when a carbonaceous material is used as the negative electrode active material is good, and lithium and the like are less likely to precipitate on the electrode surface, resulting in a lithium battery. It tends to be easy to avoid a decrease in stability such as. Further, the reactivity with the non-aqueous electrolyte solution is suppressed, gas generation is small, and a preferable lithium battery or the like tends to be easily obtained.

To measure the specific surface area by the BET method, a surface area meter (fully automatic surface area measuring device manufactured by Okura Riken) is used to pre-dry the sample at 350 ° C for 15 minutes under nitrogen flow, and then the nitrogen to atmospheric pressure is measured. Using a nitrogen helium mixed gas accurately adjusted so that the relative pressure value is 0.3, the nitrogen adsorption BET 1-point method by the gas flow method is used. The specific surface area obtained by the measurement is defined as the BET specific surface area of the carbonaceous material in the present specification.

(5) Circularity When the circularity is measured as the degree of sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined by "circularity = (peripheral length of a corresponding circle having the same area as the projected particle shape) / (actual peripheral length of the projected particle shape)", and is theoretical when the circularity is 1. Become a true sphere.

The circularity of the particles in which the particle size of the carbonaceous material is in the range of 3 to 40 μm is preferably closer to 1, and preferably 0.1 or more, more preferably 0.5 or more, still more preferably 0.8 or more. , 0.85 or more is particularly preferable, and 0.9 or more is most preferable.

The high current density charge / discharge characteristics of lithium batteries and the like improve as the circularity increases. Therefore, when the circularity is lower than the above range, the filling property of the negative electrode active material is lowered, the resistance between the particles is increased, and the high current density charge / discharge characteristics for a short time may be lowered.

The circularity of the carbonaceous material is measured using a flow-type particle image analyzer (FPIA manufactured by Sysmex Corporation). Specifically, about 0.2 g of a sample is dispersed in a 0.2 mass% aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and an ultrasonic wave of 28 kHz is output at an output of 60 W. After irradiation for a minute, the detection range is specified as 0.6 to 400 μm, and particles having a particle size in the range of 3 to 40 μm are measured. The circularity obtained by the measurement is defined as the circularity of the carbonaceous material in the present specification.

The method for improving the circularity is not particularly limited, but a spherical shape obtained by subjecting it to a spherical shape is preferable because the shape of the interparticle voids when the electrode body is formed is adjusted. Examples of the spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, and a mechanical / physical treatment method of granulating a plurality of fine particles by a binder or the adhesive force of the particles themselves. Can be mentioned.

(6) Tap density The tap density of the carbonaceous material is not particularly limited, but is usually 0.1 g · cm ^-3 or more, preferably 0.5 g · cm ^-3 or more, and 0.7 g · cm ^-3 or more. More preferably, 1 g · cm ^-3 or more is particularly preferable, 2 g · cm ^-3 or less is preferable, 1.8 g · cm ^-3 or less is further preferable, and 1.6 g · cm ^-3 or less is particularly preferable.

When the tap density is within the above range, a sufficient filling density can be secured when used as a negative electrode, and a high-capacity lithium battery or the like tends to be easily obtained. Further, the voids between the particles in the electrode are not excessively reduced, the conductivity between the particles is easily ensured, and preferable battery characteristics tend to be easily obtained.

The tap density is measured as follows. After passing the sample through a sieve with an opening of 300 μm and dropping the sample into a tapping cell of 20 cm ³ to fill the sample up to the upper end surface of the cell, a powder density measuring instrument (for example, a tap denser manufactured by Seishin Enterprise Co., Ltd.) is used. Using this, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the carbonaceous material in the present specification.

(7) Orientation ratio The orientation ratio of the carbonaceous material is not particularly limited, but is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. .. When the orientation ratio is within the above range, higher high-density charge / discharge characteristics tend to be easily obtained. The upper limit of the above range is the theoretical upper limit of the orientation ratio of the carbonaceous material.

The orientation ratio of the carbonaceous material is determined by pressure-molding the sample and then measuring it by X-ray diffraction. Specifically, a molded product obtained by filling 0.47 g of a sample into a molding machine having a diameter of 17 mm and compressing it at 58.8 MN · m- ² becomes the same surface as the surface of the sample holder for measurement using clay. And measure the X-ray diffraction. From the peak intensities of (110) diffraction and (004) diffraction of the obtained carbon, the ratio expressed by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. The orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material in the present specification.

The X-ray diffraction measurement conditions are as follows. In addition, "2θ" indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degrees Light receiving slit = 0.15 mm
Scattering slit = 0.5 degrees ・ Measurement range and step angle / measurement time:
(110) Surface: 75 degrees ≤ 2θ ≤ 80 degrees 1 degree / 60 seconds (004) Surface: 52 degrees ≤ 2θ ≤ 57 degrees 1 degree / 60 seconds

(8) Aspect ratio (powder)
The aspect ratio of the carbonaceous material is not particularly limited, but is usually 1 or more, usually 10 or less, preferably 8 or less, and more preferably 5 or less. If the aspect ratio exceeds the above range, streaks or a uniform coated surface cannot be obtained at the time of plate formation, and the high current density charge / discharge characteristics may deteriorate. The lower limit of the above range is the theoretical lower limit of the aspect ratio of the carbonaceous material.

The aspect ratio of the carbonaceous material is measured by magnifying and observing the particles of the carbonaceous material with a scanning electron microscope. Specifically, any 50 carbonaceous material particles fixed to the end face of a metal having a thickness of 50 μm or less were selected, and the stage on which the sample was fixed was rotated and tilted for each, and observed three-dimensionally. The longest diameter P of the carbonaceous material particles at that time and the shortest diameter Q orthogonal to it are measured, and the average value of P / Q is obtained. The aspect ratio (P / Q) obtained by the measurement is defined as the aspect ratio of the carbonaceous material in the present specification.

(9) Electrode manufacturing Any known method can be used for manufacturing the negative electrode. For example, a binder, a solvent, a thickener, a conductive material, a filler, and the like are added to the negative electrode active material to form a slurry-like negative electrode forming material, which is applied to a current collector, dried, and then pressed. Thereby, the negative electrode active material layer can be formed.

The thickness of the negative electrode active material layer per side at the stage immediately before the non-aqueous electrolyte injection step of a lithium battery or the like is not particularly limited, but is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more. Further, it is usually 150 μm or less, preferably 120 μm or less, and more preferably 100 μm or less. When the thickness of the negative electrode active material is within this range, the non-aqueous electrolyte solution easily permeates to the vicinity of the current collector interface, and the high current density charge / discharge characteristics tend to be improved. Further, since the volume ratio of the current collector to the negative electrode active material does not become excessively large, the capacity of the battery tends to be kept high. The negative electrode active material may be roll-molded to form a sheet electrode, or may be compression-molded to form a pellet electrode.

(10) Current collector A known current collector can be arbitrarily used as the current collector for holding the negative electrode active material. Examples of the current collector of the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel, but copper is particularly preferable from the viewpoint of ease of processing and cost.

When the current collector is made of a metal material, the shape of the current collector may be, for example, a metal foil, a metal column, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foamed metal, or the like. Among these, a metal thin film is preferable, a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable.

When the thickness of the copper foil is thinner than 25 μm, a copper alloy having higher strength than pure copper (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) can be used.

The thickness of the current collector is not particularly limited and is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, preferably 50 μm or less. Is more preferable. When the thickness of the metal film is within this range, the strength is easily maintained, deformation is prevented, and the coatability of the negative electrode active material tends to be improved. The current collector may be in the form of a mesh.

(11) Ratio of thickness between current collector and negative electrode active material layer The ratio of thickness between current collector and negative electrode active material layer is not particularly limited, but "(Negative electrode activity on one side immediately before injection of non-aqueous electrolyte solution) The value of "material layer thickness) / (thickness of current collector)" is usually preferably 150 or less, 20 or less, more preferably 10 or less, and usually 0.1 or more, 0.4 or more, 1 The above is more preferable.

When the ratio of the thickness of the current collector to the negative electrode active material layer is within the above range, it is easy to suppress heat generation due to Joule heat during high current density charging / discharging, and the volume ratio of the current collector to the negative electrode active material. Does not become excessively large, so that it tends to be easy to maintain a high battery capacity.

(12) Electrode density The electrode structure when the negative electrode active material is converted into an electrode is not particularly limited, but the density of the negative electrode active material existing on the current collector is preferably 1 g · cm ^-3 or more, preferably 1.2 g. Cm- ³ or more is more preferable, 1.3 g cm- ³ or more is further preferable, 2.2 g cm- ³ or less is preferable, 2.1 g cm- ³ or less is more preferable, and 2.0 g. cm ^-3 and more preferably less, 1.9 g · ^{cm -3} or less are particularly preferred. When the density of the negative electrode active material existing on the current collector is within the above range, the negative electrode active material particles are not easily destroyed, the initial irreversible capacity of a lithium battery or the like is increased, and the current collector / negative electrode active material is increased. Deterioration of high current density charge / discharge characteristics due to a decrease in permeability of the non-aqueous electrolyte solution to the vicinity of the interface tends to be suppressed. Further, the conductivity between the negative electrode active materials can be ensured, and the battery capacity per unit volume can be increased without increasing the battery resistance.

(13) Binder The slurry for forming the negative electrode active material layer is not particularly limited, but usually, a solvent mixed with a binder (binder), a thickener, or the like is added to the negative electrode active material. Prepared. The binder for binding the negative electrode active material is not particularly limited as long as it is a non-aqueous electrolyte solution or a material stable to the solvent used in electrode production.

Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, and NBR ( Acrylonitrile-butadiene rubber), rubber-like polymers such as ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or hydrogen additive thereof; EPDM (ethylene-propylene-diene ternary copolymer), styrene-ethylene- Thermoplastic elastomeric polymers such as butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer Soft resinous polymers such as coalesced and propylene / α-olefin copolymers; fluoropolymers such as polyvinylidene polyvinylidene, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers; alkalis Examples thereof include a polymer composition having ionic conductivity of metal ions (particularly lithium ions). These may be used alone or in any combination and ratio of two or more.

The type of solvent for forming the slurry is particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and the conductive material used as required. However, either an aqueous solvent or an organic solvent may be used.

Examples of aqueous solvents include water, alcohol and the like, and examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N. , N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like. ..

In particular, when an aqueous solvent is used, it is preferable to include a dispersant or the like in addition to the thickener and slurry using a latex such as SBR. As these solvents, one type may be used alone, or two or more types may be used in any combination and ratio.

The ratio of the binder to the negative electrode active material is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 0.6% by mass or more, and 20% by mass or less. It is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 8% by mass or less. If the ratio of the binder to the negative electrode active material is within the above range, the ratio of the binder that does not contribute to the battery capacity does not increase, so that the battery capacity is unlikely to decrease. Further, the strength of the negative electrode is less likely to decrease.

In particular, when the slurry as the negative electrode forming material contains a rubber-like polymer typified by SBR as a main component, the ratio of the binder to the negative electrode active material is not particularly limited, but is usually 0.1% by mass or more. Yes, 0.5% by mass or more is preferable, 0.6% by mass or more is more preferable, and usually 5% by mass or less, 3% by mass or less is preferable, and 2% by mass or less is more preferable.

When the slurry contains a fluorine-based polymer typified by polyvinylidene fluoride as a main component, the ratio to the negative electrode active material is not particularly limited, but is usually 1% by mass or more, preferably 2% by mass or more. 3% by mass or more is more preferable, and usually 15% by mass or less, 10% by mass or less is preferable, and 8% by mass or less is more preferable.

Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in any combination and ratio of two or more.

When a thickener is used, the ratio of the thickener to the negative electrode active material is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 0.6% by mass or more. It is preferable, and usually it is 5% by mass or less, preferably 3% by mass or less, and further preferably 2% by mass or less. When the ratio of the thickener to the negative electrode active material is within the above range, the coating property of the slurry tends to be good. Further, the ratio of the negative electrode active material to the negative electrode active material layer is also appropriate, and the decrease in battery capacity and the increase in resistance between the negative electrode active materials tend to be suppressed.

<3-1-3-3. Composition, physical properties, preparation method of metal compound material and negative electrode using metal compound material>
As the metal compound-based material used as the negative electrode active material, if lithium can be occluded and released, a single metal or alloy forming a lithium alloy, or their oxides, carbides, nitrides, silices, sulfides, etc. It is not particularly limited to any compound such as a phosphate. Examples of such metal compounds include compounds containing metals such as Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, and Zn. Among them, it is preferable that it is a simple substance metal or alloy forming a lithium alloy, and a metal / metalloid element of Group 13 or 14 (that is, excluding carbon. Hereinafter, the metal and the metalloid are collectively referred to as "metal". It is more preferable to have a material containing (referred to as), and further, silicon (Si), tin (Sn) or lead (Pb) (hereinafter, these three elements may be referred to as "specific metal elements"). It is preferably a simple substance metal, an alloy containing these atoms, or a compound of those metals (specific metal element). Elemental metals, alloys and compounds of silicon, and elemental metals, alloys and compounds of tin are particularly preferred. One of these may be used alone, or two or more thereof may be used in any combination and ratio.

Examples of a negative electrode active material having at least one atom selected from a specific metal element include a single metal of any one specific metal element, an alloy consisting of two or more specific metal elements, and one or two or more types. Specified metal element and other alloys consisting of one or more metal elements, compounds containing one or more specified metal elements, or oxides, carbides, nitrides of the compounds. -Examples include complex compounds such as siliceous substances, sulfides, and phosphors. By using these metal simple substances, alloys or metal compounds as the negative electrode active material, it is possible to increase the capacity of lithium batteries and the like.

Further, a compound in which these composite compounds are complicatedly bonded to several kinds of elements such as a simple substance of a metal, an alloy, or a non-metal element can be mentioned as an example. More specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. Further, for example, in tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not act as a negative electrode, and a non-metal element can also be used. ..

Among these negative electrode active materials, since the capacity per unit mass is large when a lithium battery or the like is used, a single metal of any one specific metal element, an alloy of two or more specific metal elements, or a specific metal element. Oxides, carbides, nitrides, etc. are preferable, and in particular, from the viewpoint of capacity per unit mass and environmental load, simple metals of silicon and / or tin, alloys, oxides, carbides, nitrides, etc. are preferable. The most preferable are simple metals, alloys, oxides and carbides.

Further, although the capacity per unit mass of a lithium battery or the like is inferior to that of using a simple substance or an alloy, the following compounds containing silicon and / or tin are also preferable because they are excellent in cycle characteristics.

-The element ratio of silicon and / or tin to oxygen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. “Silicon and / or tin oxide” of 3 or less, more preferably 1.1 or less.
-The element ratio of silicon and / or tin to nitrogen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. "Silicon and / or tin nitride" of 3 or less, more preferably 1.1 or less.
-The element ratio of silicon and / or tin to carbon is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. "Carbides of silicon and / or tin" of 3 or less, more preferably 1.1 or less.

As the above-mentioned negative electrode active material, any one type may be used alone, or two or more types may be used in any combination and ratio.

The negative electrode in the lithium battery of the present embodiment can be manufactured by any known method. Examples of the method for manufacturing the negative electrode include a method in which the above-mentioned negative electrode active material with a binder, a conductive material, etc. added is directly rolled to form a sheet electrode, and a method in which compression molding is performed to obtain a pellet electrode. However, usually, the above-mentioned negative electrode active material is contained on a current collector for a negative electrode (hereinafter, may be referred to as a “negative electrode current collector”) by a method such as a coating method, a vapor deposition method, a sputtering method, or a plating method. A method of forming a thin film layer (negative electrode active material layer) is used. In this case, a binder, a thickener, a conductive material, a solvent, etc. are added to the above-mentioned negative electrode active material to form a slurry, which is applied to the negative electrode current collector, dried, and then pressed to increase the density. , A negative electrode active material layer is formed on the negative electrode current collector.

Examples of the material of the negative electrode current collector include steel, copper alloy, nickel, nickel alloy, stainless steel and the like. Of these, copper foil is preferable from the viewpoint of easy processing into a thin film and cost.

The thickness of the negative electrode current collector is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, usually 100 μm or less, preferably 50 μm or less from the viewpoint of ensuring the capacity of the entire battery and ensuring handleability. is there.

In addition, in order to improve the binding effect with the negative electrode active material layer formed on the surface, it is preferable that the surface of these negative electrode current collectors is roughened in advance. The method for roughening the surface is not particularly limited, and a known method can be applied. For example, blasting, rolling with a rough surface roll, mechanical polishing method for polishing the surface of a current collector with a polishing cloth paper to which abrasive particles are fixed, a grindstone, emeri buff, a wire brush equipped with a steel wire, etc., electrolytic polishing method , Chemical polishing method and the like.

The slurry for forming the negative electrode active material layer is usually prepared by adding a binder, a thickener, or the like to the negative electrode material. The term "negative electrode material" as used herein refers to a material in which the negative electrode active material and the conductive material are combined.

The content of the negative electrode active material in the negative electrode material is not particularly limited, but is usually 70% by mass or more, particularly preferably 75% by mass or more, and usually 97% by mass or less, particularly preferably 95% by mass or less. When the content of the negative electrode active material is within the above range, it is easy to secure the capacity of the lithium battery or the like, and it is easy to secure the strength of the negative electrode. When two or more negative electrode active materials are used in combination, the total amount of the negative electrode active materials may satisfy the above range.

The conductive material used for the negative electrode is not particularly limited, and examples thereof include metal materials such as copper and nickel; carbon materials such as graphite and carbon black. One of these may be used alone, or two or more thereof may be used in any combination and ratio. In particular, it is preferable to use a carbon material as the conductive material because the carbon material also acts as an active material. The content of the conductive material in the negative electrode material is not particularly limited, but is usually preferably 3% by mass or more, particularly preferably 5% by mass or more, and usually 30% by mass or less, particularly preferably 25% by mass or less. When the content of the conductive material is within the above range, it is easy to secure the conductivity, and it is easy to secure the battery capacity and strength. When two or more conductive materials are used in combination, the total amount of the conductive materials may satisfy the above range.

As the binder used for the negative electrode, any binder can be used as long as it is a material that is safe for the solvent and electrolytic solution used in the production of the electrode. For example, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene-acrylic acid copolymer, ethylene / methacrylic acid copolymer and the like can be mentioned in particular. Not limited. One of these may be used alone, or two or more thereof may be used in any combination and ratio. The content of the binder is not particularly limited, but is usually 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and usually 10 parts by mass or less, particularly 8 parts by mass or less with respect to 100 parts by mass of the negative electrode material. Is preferable. When the content of the binder is within the above range, it is easy to maintain the strength of the negative electrode, and it is easy to secure the battery capacity and conductivity. When two or more binders are used in combination, the total amount of the binders may satisfy the above range.

The thickener used for the negative electrode is not particularly limited, and examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein. One of these may be used alone, or two or more thereof may be used in any combination and ratio. The thickener may be used as needed, but when used, the content of the thickener in the negative electrode active material layer is usually in the range of 0.5% by mass or more and 5% by mass or less. Is preferable.

The slurry for forming the negative electrode active material layer is prepared by mixing the negative electrode active material with a conductive material, a binder, and a thickener as necessary, and using an aqueous solvent or an organic solvent as a dispersion medium. Can be done. Water is usually used as the aqueous solvent, but a solvent other than water such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone is used in combination with water at a ratio of about 30% by mass or less. You can also do it. The organic solvent is usually cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbides such as anisole, toluene and xylene. Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, and among these, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide and the like. Is preferable. It should be noted that any one of these may be used alone, or two or more thereof may be used in any combination and ratio.

The viscosity of the slurry is not particularly limited as long as it can be applied onto the current collector. The amount of the solvent used may be changed at the time of preparing the slurry so that the viscosity can be applied, and the slurry may be appropriately adjusted.

The obtained slurry is applied onto the above-mentioned negative electrode current collector, dried, and then pressed to form a negative electrode active material layer. The method of application is not particularly limited, and a method known per se can be used. The drying method is not particularly limited, and known methods such as natural drying, heat drying, and vacuum drying can be used.

The electrode structure when the negative electrode active material is made into an electrode by the above method is not particularly limited, but the density of the active material existing on the current collector is preferably 1 g · cm ^-3 or more, preferably 1.2 g · cm. ^-3 or more is more preferable, 1.3 g · cm ^-3 or more is particularly preferable, 2.2 g · cm ^-3 or less is preferable, 2.1 g · cm ^-3 or less is more preferable, and 2.0 g · cm ^{−. 3} or less is more preferable, and 1.9 g · cm ^-3 or less is particularly preferable.

When the density of the negative electrode active material existing on the current collector is within the above range, the negative electrode active material particles are not easily destroyed, the initial irreversible capacity of the lithium battery or the like is increased, and the current collector / active material interface is increased. Deterioration of high current density charge / discharge characteristics due to a decrease in permeability of the non-aqueous electrolyte solution to the vicinity tends to be suppressed. Further, the conductivity between the negative electrode active materials can be ensured, and the capacity per unit volume can be increased without increasing the battery resistance.

<3-1-3-4. Composition, physical properties, preparation method of negative electrode using carbonaceous material and metal compound material>
As the negative electrode active material, a metal compound-based material and the carbonaceous material may be contained. Here, the negative electrode active material containing the metal compound-based material and the carbonaceous material is a single metal or alloy forming a lithium alloy, or a compound such as an oxide, a carbide, a nitride, a silice, or a sulfide thereof. Any of them may be a mixture in which carbonaceous materials are mixed in the state of particles independent of each other, a single metal or alloy forming a lithium alloy, or oxides, carbides, nitrides, silices, sulfides and the like thereof. The compound may be a composite in which the above compound is present on the surface or inside of a carbonaceous material. In the present specification, the composite may particularly contain a metal compound-based material and a carbonaceous material, and the properties and forms thereof are not particularly limited, but the metal compound-based material and the carbonaceous material are physically and / or Those that are integrated by chemical bonding are preferable. In a more preferable form, the metal compound-based material and the carbonaceous material are in a state in which each solid component is dispersed and present to the extent that they are present at least on the surface of the composite and inside the bulk, and they are physically present. It is in the form in which a carbonaceous material is present to integrate by target and / or chemical bond.

In such a form, the particle surface is observed with a scanning electron microscope, the particles are embedded in a resin to prepare a thin piece of the resin, and the particle cross section is cut out, or the coating film composed of the particles is formed with a cross section polisher. After producing and cutting out the particle cross section, observation is possible by an observation method such as particle cross section observation with a scanning electron microscope.

The content ratio of the metal compound-based material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material is not particularly limited, but is usually 0.1% by mass or more, preferably 1% by mass or more, and more preferably 1. .5% by mass or more, more preferably 2% by mass or more, particularly preferably 3% by mass or more, and usually 99% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably. It is 30% by mass or less, more preferably 25% by mass or less, particularly preferably 15% by mass or less, and most preferably 10% by mass or less. Within this range, a sufficient capacity tends to be easily obtained.

It is preferable that the carbonaceous material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material satisfies the requirements described in <3-1-3-2> above. Further, it is desirable that the following conditions are satisfied for the metal compound-based material.

As the elemental metal or alloy forming the lithium alloy, any conventionally known elemental metal can be used, but from the viewpoint of capacity and cycle life, the elemental metal forming the lithium alloy is, for example, Fe, Co, Sb, etc. A metal or a compound thereof selected from the group consisting of Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, P, S, V, Mn, Nb, Mo, Cu, Zn, Ge, In, Ti and the like. Is preferable. Further, as the alloy for forming the lithium alloy, a metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W or a compound thereof is preferable.

The single metals or alloys that form a lithium alloy, or compounds such as oxides, carbides, nitrides, silices, and sulfides thereof are metal oxides, metal carbides, metal nitrides, metal siliceates, and metal sulfides. And so on. Further, an alloy composed of two or more kinds of metals may be used. Among these, Si or a Si compound is preferable in terms of increasing the capacity. In the present specification, Si or Si compounds are collectively referred to as Si compounds. Specific examples of the Si compound include SiOx, SiNx, SiCx, SiZxOy (Z is C or N) and the like, preferably SiOx. The value of x in the above general formula is not particularly limited, but is usually 0 ≦ x <2. The general formula SiOx is obtained by using silicon dioxide (SiO ₂ ) and metal Si (Si) as raw materials. SiOx has a larger theoretical capacity than graphite, and amorphous Si or nano-sized Si crystals allow alkaline ions such as lithium ions to easily enter and exit, making it possible to obtain a high capacity.

The value of x in SiOx is not particularly limited, but usually x is 0 ≦ x <2, preferably 0.2 or more, more preferably 0.4 or more, still more preferably 0.6 or more, and also. It is preferably 1.8 or less, more preferably 1.6 or less, and even more preferably 1.4 or less. Within this range, a high capacity is likely to be secured, and at the same time, the irreversible capacity due to the combination of Li and oxygen tends to be reduced.

The method for confirming that the metal compound-based material is a metal material that can be alloyed with lithium is not particularly limited, but identification of the metal particle phase by X-ray diffraction and observation of the particle structure by an electron microscope. And elemental analysis, elemental analysis by fluorescent X-ray, and the like.

The average particle size (d50) of the metal compound-based material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material is not particularly limited, but is usually 0.01 μm or more, preferably 0, from the viewpoint of cycle life. It is 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.3 μm or more, and usually 10 μm or less, preferably 9 μm or less, more preferably 8 μm or less. When the average particle size (d50) is within the above range, the volume expansion due to charge / discharge is reduced, and good cycle characteristics can be obtained while maintaining the charge / discharge capacity. In the present specification, the average particle size (d50) of the metal compound-based material means a value obtained by a laser diffraction / scattering type particle size distribution measuring method or the like.

The specific surface area is not particularly limited by the BET method of the metal compound-based material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material, but is usually 0.5 m ² / g or more, preferably 1 m ² / g or more. In addition, it is usually 60 m ² / g or less, preferably 40 m ² / g. When the specific surface area of the metal particles that can be alloyed with Li by the BET method is within the above range, the charge / discharge efficiency and discharge capacity of the battery are high, lithium is taken in and out quickly in high-speed charge / discharge, and the rate characteristics are excellent, which is preferable.

The amount of oxygen contained in the metal compound-based material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material is not particularly limited, but is usually 0.01% by mass or more, preferably 0.05% by mass or more. Further, it is usually 8% by mass or less, preferably 5% by mass or less. The oxygen distribution state in the particle may be present near the surface, inside the particle, or uniformly in the particle, but it is particularly preferable that the oxygen is present near the surface. When the oxygen content of the metal compound-based material is within the above range, the volume expansion due to charging / discharging is suppressed due to the strong bond between Si and O, and the cycle characteristics are excellent, which is preferable.

Further, for the preparation of the negative electrode of the metal compound-based material used for the negative electrode active material containing the metal compound-based material and the carbonaceous material, the one described in <3-1-3-2> carbonaceous material may be used. it can.

<3-1-3-5. Composition, physical characteristics, preparation method of lithium-containing metal composite oxide material and negative electrode using lithium-containing metal composite oxide material>
The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a lithium-containing composite metal oxide material containing titanium is preferable, and composite oxidation of lithium and titanium is preferable. A substance (hereinafter, abbreviated as "lithium-titanium composite oxide") is particularly preferable. That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a lithium battery because the output resistance is greatly reduced.

Further, at least lithium or titanium of the lithium titanium composite oxide is selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. Those substituted with one kind of element are also preferable.

Preferred lithium-titanium composite oxide as the negative electrode active material includes lithium-titanium composite oxide represented by the following general formula (6).

LixTiyMzO ₄ (6)
[In the general formula (5), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. Further, in the general formula (6), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, and 0 ≦ z ≦ 1.6 are the cases of doping and dedoping of lithium ions. It is preferable because the structure of is stable. ]

Among the compositions represented by the above general formula (6),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because it has a good balance of battery performance.

Particularly preferable typical compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). It is ₄ . As for the structure of z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.

In addition to the above requirements, the lithium-titanium composite oxide as the negative electrode active material in the present embodiment further has at least one of the characteristics such as physical properties and shape shown in the following (1) to (13). It is preferable to satisfy, and it is particularly preferable to satisfy two or more kinds at the same time.

(1) BET Specific Surface Area The BET specific surface area of the lithium titanium composite oxide used as the negative electrode active material preferably has a specific surface area value of 0.5 m ² · g ^-1 or more measured by the BET method. 7 m ² · g ^-1 or more is more preferable, 1.0 m ² · g ^-1 or more is further preferable, 1.5 m ² · g ^-1 or more is particularly preferable, and 200 m ² · g ^-1 or less is preferable, and 100 m. ² · g ^-1 or less is more preferable, 50 m ² · g ^-1 or less is further preferable, and 25 m ² · g ^-1 or less is particularly preferable.

When the BET specific surface area is within the above range, the reaction area of the negative electrode active material in contact with the non-aqueous electrolyte solution is unlikely to decrease, and the increase in output resistance tends to be suppressed. Further, the increase of the surface and end face portions of the titanium-containing metal oxide crystal is suppressed, and the distortion of the crystal due to this is less likely to occur, so that a preferable lithium battery or the like can be easily obtained.

To measure the specific surface area of the lithium-titanium composite oxide by the BET method, the sample was pre-dried at 350 ° C. for 15 minutes under nitrogen flow using a surface meter (fully automatic surface area measuring device manufactured by Okura Riken). After that, the nitrogen adsorption BET 1-point method by the gas flow method is performed using a nitrogen-helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen with respect to the atmospheric pressure is 0.3. The specific surface area obtained by the measurement is defined as the BET specific surface area of the lithium titanium composite oxide in the present specification.

(2) Volume-based average particle size The volume-based average particle size of the lithium titanium composite oxide (secondary particle size when the primary particles are aggregated to form secondary particles) is determined by the laser diffraction / scattering method. It is defined by the obtained volume-based average particle size (median diameter).

The volume-based average particle size of the lithium-titanium composite oxide is not particularly limited, but is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 0.7 μm or more, and usually 50 μm or less, 40 μm. The following is preferable, 30 μm or less is more preferable, and 25 μm or less is further preferable.

The volume-based average particle size of the lithium-titanium composite oxide is specifically measured in a 0.2 mass% aqueous solution (10 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant. The powder is dispersed, and a laser diffraction / scattering type particle size distribution meter (LA-700 manufactured by Horiba Seisakusho Co., Ltd.) is used. The median diameter obtained by the measurement is defined as the volume-based average particle diameter of the carbonaceous material in the present specification.

When the volume average particle diameter of the lithium-titanium composite oxide is within the above range, the amount of the binder used at the time of producing the negative electrode can be suppressed, and as a result, it becomes easy to prevent a decrease in the battery capacity. Further, when the negative electrode plate is formed, the coated surface tends to be uniform, and there is an advantage that the battery manufacturing process can be efficiently performed.

(3) Average primary particle size When the primary particles are aggregated to form secondary particles, the average primary particle size of the lithium titanium composite oxide is not particularly limited, but is usually 0.01 μm or more. 0.05 μm or more is preferable, 0.1 μm or more is more preferable, 0.2 μm or more is further preferable, and usually 2 μm or less, 1.6 μm or less is preferable, 1.3 μm or less is more preferable, and 1 μm or less is further preferable. preferable. When the volume-based average primary particle diameter is within the above range, spherical secondary particles are easily formed, powder filling property is improved, and specific surface area is easily secured, so that battery performance such as output characteristics is deteriorated. Tends to be suppressed.

The average primary particle size of the lithium-titanium composite oxide is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph having a magnification at which the particles can be confirmed, for example, a magnification of 10,000 to 100,000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is arbitrarily set to 50 pieces. The average primary particle size can be obtained by obtaining the primary particles and taking the average value.

(4) Shape The shape of the lithium-titanium composite oxide particles may be any of the conventionally used particles such as agglomerates, polyhedrons, spheres, elliptical spheres, plates, needles, and columns, and among them, the primary particles are aggregated. It is preferable that the secondary particles are formed in a spherical shape or an elliptical spherical shape.

Normally, in an electrochemical element, the active material in the electrode expands and contracts with the charge and discharge, so that the stress tends to cause deterioration such as destruction of the negative electrode active material and breakage of the conductive path. Therefore, the stress of expansion and contraction can be alleviated in the case where the primary particles aggregate to form the secondary particles, as compared with the negative electrode active material of the single particles containing only the primary particles, so that deterioration tends to be less likely to occur.

In addition, since spherical or elliptical spherical particles have less orientation during molding of the electrode than axially oriented particles such as plate-shaped particles, the expansion and contraction of the electrode during charging and discharging is also smaller, and the electrode is manufactured. It is also preferable to mix it with the conductive material because it is easy to mix uniformly.

(5) Tap Density Tap density lithium-titanium composite oxide is preferably from 0.05 g · ^{cm -3} or more, more preferably 0.1 g · ^{cm -3} or more, more preferably 0.2 g · ^{cm -3} or more, 0.4 g · cm ^-3 or more is particularly preferable, 2.8 g · cm ^-3 or less is more preferable, 2.4 g · cm ^-3 or less is further preferable, and 2 g · cm ^-3 or less is particularly preferable. When the tap density of the lithium-titanium composite oxide is within the above range, a sufficient packing density can be secured when used as a negative electrode, and a large contact area between particles can be secured, so that the resistance between particles increases. It is difficult, and the increase in output resistance of lithium batteries and the like tends to be suppressed. Further, since the voids between the particles in the electrode are also appropriate and the flow path of the non-aqueous electrolytic solution can be secured, the increase in output resistance tends to be suppressed easily.

The tap density of the lithium-titanium composite oxide is measured as follows. After passing the sample through a sieve with an opening of 300 μm and dropping the sample into a tapping cell of 20 cm ³ to fill the sample up to the upper end surface of the cell, a powder density measuring instrument (for example, a tap denser manufactured by Seishin Enterprise Co., Ltd.) is used. Using this, tapping with a stroke length of 10 mm is performed 1000 times, and the density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the lithium titanium composite oxide in the present specification.

(6) Circularity The degree of sphere of the lithium-titanium composite oxide is preferably within the following range when the circularity is measured. The circularity is defined by "circularity = (peripheral length of a corresponding circle having the same area as the projected particle shape) / (actual peripheral length of the projected particle shape)", and when the circularity is 1, a theoretical true sphere. It becomes.

The circularity of the lithium-titanium composite oxide is preferably closer to 1, usually 0.10 or more, preferably 0.80 or more, more preferably 0.85 or more, still more preferably 0.90 or more. The high current density charge / discharge characteristics improve as the circularity increases. Therefore, when the circularity is within the above range, it is possible to suppress an increase in resistance between particles without deteriorating the filling property of the negative electrode active material and suppress a decrease in high current density charge / discharge characteristics for a short time. it can.

The circularity of the lithium-titanium composite oxide is measured using a flow-type particle image analyzer (FPIA manufactured by Sysmex Corporation). Specifically, about 0.2 g of a sample is dispersed in a 0.2 mass% aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and an ultrasonic wave of 28 kHz is output at an output of 60 W. After irradiation for 1 minute, the detection range is specified as 0.6 to 400 μm, and the measurement is performed on particles having a particle size in the range of 3 to 40 μm. The circularity obtained by the measurement is defined as the circularity of the lithium titanium composite oxide in the present specification.

(7) Aspect ratio The aspect ratio of the lithium-titanium composite oxide is not particularly limited, but is usually 1 or more, usually 5 or less, preferably 4 or less, more preferably 3 or less, still more preferably 2 or less. When the aspect ratio is within the above range, streaks are less likely to occur during electrode plate formation, and a uniform coated surface can be easily obtained, so that deterioration of high current density charge / discharge characteristics for a short time tends to be suppressed. .. The lower limit of the above range is the theoretical lower limit of the aspect ratio of the lithium titanium composite oxide.

The aspect ratio of the lithium-titanium composite oxide is measured by magnifying and observing the particles of the lithium-titanium composite oxide with a scanning electron microscope. When any 50 lithium-titanium composite oxide particles fixed to the end face of a metal having a thickness of 50 μm or less are selected, and the stage on which the sample is fixed is rotated and tilted for each, and observed three-dimensionally. The longest diameter P'of the particle and the shortest diameter Q'orthogonal to it are measured, and the average value of P'/ Q'is calculated. The aspect ratio (P'/ Q') obtained by the measurement is defined as the aspect ratio of the lithium titanium composite oxide in the present specification.

(8) Method for Producing Lithium-Titanium Composite Oxide The method for producing the lithium-titanium composite oxide is not particularly limited, but some methods are mentioned, and a general method is used as a method for producing an inorganic compound.

For example, a method in which a titanium raw material such as titanium oxide, a raw material of another element as required, and a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ are uniformly mixed and fired at a high temperature to obtain an active material. Can be mentioned.

In particular, various methods can be considered for producing a spherical or elliptical spherical active material. As an example, a titanium raw material such as titanium oxide and, if necessary, a raw material of another element are dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to create a spherical precursor. Examples thereof include a method of recovering the mixture, drying it as necessary, adding a Li source such as LiOH, Li ₂ CO ₃ and Li NO ₃ and firing at a high temperature to obtain an active material.

As another example, a titanium raw material such as titanium oxide and, if necessary, a raw material of another element are dissolved or pulverized and dispersed in a solvent such as water, and the material is dried and molded by a spray dryer or the like to form a spherical shape. or a precursor ellipsoidal, this _LiOH, and fired at a high temperature by adding Li ₂ CO 3, LiNO Li source such as ₃ and a method of obtaining an active material.

As yet another method, a titanium raw material such as titanium oxide, a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ and, if necessary, a raw material of another element are dissolved or pulverized in a solvent such as water. Examples thereof include a method in which the residue is dispersed and dried and molded with a spray dryer or the like to form a spherical or elliptical spherical precursor, which is then fired at a high temperature to obtain an active material.

Further, in the steps in the various methods described above, elements other than Ti, for example, Al, Mn, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, It is also possible to have C, Si, Sn, Ag present in the titanium-containing metal oxide structure and / or in contact with the titanium-containing oxide. By allowing these elements to exist in the above-mentioned form and containing them in the negative electrode active material, it is possible to control the operating voltage and capacity of a lithium battery or the like.

(9) Electrode production Any known method can be used for electrode production. For example, it is produced by adding a binder, a solvent, and if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried, and then pressed. Can be done.

The thickness of the negative electrode active material layer per side at the stage immediately before the injection step of the non-aqueous electrolyte solution in a lithium battery or the like is not particularly limited, but is usually 15 μm or more, preferably 20 μm or more, and more preferably 30 μm or more. The upper limit is 150 μm or less, preferably 120 μm or less, and more preferably 100 μm or less. Within the above range, the non-aqueous electrolyte solution can easily permeate to the vicinity of the current collector interface, so that the high current density charge / discharge characteristics tend to be high and easily maintained. Further, the volume ratio of the current collector to the negative electrode active material can be kept low, and the battery capacity tends to be kept large. The negative electrode active material may be roll-molded to form a sheet electrode, or may be compression-molded to form a pellet electrode.

(10) Current collector A known current collector can be arbitrarily used as the current collector for holding the negative electrode active material. Specific examples of the current collector of the negative electrode include metal materials such as copper, nickel, stainless steel, and nickel-plated steel, and among these, copper is particularly preferable from the viewpoint of ease of processing and cost.

Further, the shape of the current collector is not particularly limited. When the current collector is a metal material, examples thereof include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foamed metal. Among these, a metal foil film containing copper (Cu) and / or aluminum (Al) is preferable, a copper foil and an aluminum foil are more preferable, and a rolled copper foil by a rolling method and an electrolysis method are more preferable. It is an electrolytic copper foil by.

When the thickness of the copper foil is thinner than 25 μm, a copper alloy having higher strength than pure copper (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) can be used. Further, since the aluminum foil has a light specific gravity, it can reduce the mass of the battery when used as a current collector, and thus can be preferably used.

Further, since the rolled copper foil has copper crystals arranged in the rolling direction, it is difficult to crack even if the negative electrode is rounded densely or at an acute angle, so that it can be suitably used for a small cylindrical battery.

In the electrolytic copper foil, for example, a metal drum is immersed in a non-aqueous electrolytic solution in which copper ions are dissolved, and a current is passed while rotating the drum to deposit copper on the surface of the drum and peel it off. Can be obtained. Further, copper may be deposited on the surface of the rolled copper foil by an electrolytic method. One side or both sides of the copper foil may be roughened or surface-treated (for example, chromate treatment having a thickness of several nm to 1 μm, base treatment such as Ti, etc.).

The thickness of the current collector is not particularly limited and is arbitrary. It is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. When the thickness of the current collector is within the above range, the strength tends to be improved, the coatability of the negative electrode forming material (slurry) is improved, and the shape stability of the electrode tends to be improved.

(11) Ratio of thickness between current collector and active material layer The ratio of thickness between current collector and active material layer is not particularly limited, but "(one-sided active material layer immediately before injection of non-aqueous electrolyte solution) (Thickness) / (Thickness of current collector) ”is usually 150 or less, preferably 20 or less, more preferably 10 or less, and usually 0.1 or more, 0.4 or more. Preferably, 1 or more is more preferable.

When the ratio of the thickness of the current collector to the negative electrode active material layer is within the above range, heat generation due to Joule heat during high current density charging / discharging tends to be suppressed, and the current collector with respect to the negative electrode active material. Since the volume ratio of the battery does not increase excessively, it tends to be easy to maintain a high battery capacity.

(12) Electrode Density The electrode structure when the negative electrode active material is converted into an electrode is not particularly limited. Density of the negative electrode active material present on the current collector is preferably 1 g · ^{cm -3} or more, more preferably 1.2 g · ^{cm -3} or more, more preferably 1.3 g · ^{cm -3} or more, 1 .5 g · cm ^-3 or more is particularly preferable, 3 g · cm ^-3 or less is preferable, 2.5 g · cm ^-3 or less is more preferable, 2.2 g · cm ^-3 or less is further preferable, and 2 g · cm ^{− 3} or less is particularly preferable.

When the density of the active material existing on the current collector is within the above range, the binding property between the current collector and the negative electrode active material is easily maintained, so that the dissociation between the electrode and the negative electrode active material is suppressed. Tend to be. Further, since it is easy to secure the conductivity between the negative electrode active materials, the increase in battery resistance tends to be suppressed.

(13) Binder, solvent, etc. The slurry for forming the negative electrode active material layer is usually prepared by adding a mixture of a binder (binding agent), a thickener, etc. to the negative electrode active material. To. The binder for binding the negative electrode active material is not particularly limited as long as it is a non-aqueous electrolyte solution or a material stable to the solvent used in electrode production.

Specific examples thereof include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, and fluororubber. , NBR (Acrylonitrile-butadiene rubber), rubber-like polymers such as ethylene-propylene rubber; styrene-butadiene-styrene block copolymer and its hydrogen additive; EPDM (ethylene-propylene-diene ternary copolymer), styrene Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers and their hydrogenated products; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / acetic acid Soft resinous polymers such as vinyl copolymers and propylene / α-olefin copolymers; fluorine-based highs such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymers. Molecular; Examples thereof include a polymer composition having ionic conductivity of alkali metal ions (particularly lithium ions). These may be used alone or in any combination and ratio of two or more.

The type of solvent for forming the slurry is particularly limited as long as it is a solvent capable of dissolving or dispersing a negative electrode active material, a binder, a thickener and a conductive material used as necessary. However, either an aqueous solvent or an organic solvent may be used.

Examples of aqueous solvents include water, alcohol and the like, and examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N. , N-Dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamerylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like. In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the above-mentioned thickener to form a slurry using latex such as SBR. In addition, these may use 1 type alone or 2 or more types in arbitrary combinations and ratios.

The ratio of the binder to the negative electrode active material is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 20% by mass or less. It is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 8% by mass or less. When the ratio of the binder to the negative electrode active material is within the above range, the ratio of the binder that does not contribute to the battery capacity does not become excessively large, so that the battery capacity can be maintained high and the strength of the negative electrode can be easily maintained. It is preferable in the process.

In particular, when the slurry as the negative electrode forming material contains a rubbery polymer typified by SBR as a main component, the ratio of the binder to the negative electrode active material is not particularly limited, but is usually 0.1% by mass or more. Yes, 0.5% by mass or more is preferable, 0.6% by mass or more is more preferable, and usually 5% by mass or less, 3% by mass or less is preferable, and 2% by mass or less is more preferable.

When the slurry which is the negative electrode forming material contains a fluorine-based polymer typified by polyvinylidene fluoride as a main component, the ratio to the negative electrode active material is not particularly limited, but is usually 1% by mass or more. 2% by mass or more is preferable, 3% by mass or more is more preferable, usually 15% by mass or less, 10% by mass or less is preferable, and 8% by mass or less is more preferable.

Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in any combination and ratio of two or more.

When a thickener is used, the ratio of the thickener to the negative electrode active material is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0.6% by mass or more. Is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. When the ratio of the thickener to the negative electrode active material is within the above range, the coatability of the slurry tends to be good. In addition, the ratio of the active material to the negative electrode active material layer becomes appropriate, and the decrease in battery capacity and the increase in resistance between the negative electrode active materials tend to be suppressed.

<3-1-4. Positive electrode>
The positive electrode has a positive electrode active material layer on the current collector, and the positive electrode active material layer contains a positive electrode active material. Hereinafter, the positive electrode active material will be described.

<3-1-4-1. Positive electrode active material>
The positive electrode active material used for the positive electrode will be described below.

(1) Composition The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, but for example, a substance containing lithium and at least one transition metal is preferable. Specific examples include a lithium transition metal composite oxide, a lithium-containing transition metal phosphoric acid compound, a lithium-containing transition metal silicic acid compound, and a lithium-containing transition metal boric acid compound.

As the transition metal of the lithium transition metal composite oxide, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable. Specific examples of the complex oxide, lithium cobalt complex oxide such as LiCoO _{2, LiMnO 2, LiMn 2 O 4} , Li 2 lithium-manganese composite oxides such as MnO _4, lithium-nickel composite oxide such as LiNiO ₂ Things etc. can be mentioned. Further, some of the transition metal atoms that are the main constituents of these lithium transition metal composite oxides are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si. Specific examples thereof include those substituted with other metals such as lithium-cobalt-nickel composite oxide, lithium-cobalt-manganese composite oxide, lithium-nickel-manganese composite oxide, and lithium-nickel composite oxide. -Cobalt-manganese composite oxides and the like can be mentioned.

Specific examples of the substituted ones include, for example, Li _{1 + a} Ni _0.5 Mn _0.5 O ₂ , Li _{1 + a} Ni _0.8 Co _0.2 O ₂ , Li _{1 + a} Ni _0.85 Co _0.10 Al _{0. 05} O ₂ , Li _{1 + a} Ni _0.33 Co _0.33 Mn _0.33 O ₂ , Li _{1 + a} Ni _0.45 Co _0.45 Mn _0.1 O ₂ , Li _{1 + a} Mn _1.8 Al _0.2 O ₄ , Li _{1 + a} Mn _1.5 Ni _0.5 O ₄ , xLi ₂ MnO ₃ , (1-x) Li _{1 + a} MO ₂ (M = transition metal) and the like (a = 0 <a ≦ 3.0).

The lithium-containing transition metal phosphate compound is LixMPO ₄ (M = a kind of element selected from the group consisting of transition metals of groups 4 to 11 of the 4th period of the periodic table, x is 0 <x <1.2). Can be expressed as the basic composition, and the transition metal (M) is selected from the group consisting of V, Ti, Cr, Mg, Zn, Ca, Cd, Sr, Ba, Co, Ni, Fe, Mn and Cu. It is preferably at least one element selected from the group consisting of Co, Ni, Fe, and Mn, and more preferably at least one element. For _{example, LiFePO 4, Li 3 Fe 2} (PO 4) 3, LiFeP 2 O 7 , etc. of phosphorus Santetsurui, cobalt phosphate such as LiCoPO _4, manganese phosphate such as LiMnPO _4, phosphoric acids such as LiNiPO ₄ Nickel, some of the transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Examples thereof include those substituted with other metals such as Nb and Si.

The above-mentioned "LixMPO ₄ " includes not only those having a composition represented by the composition formula but also those in which a part of the transition metal (M) site in the crystal structure is replaced with another element. means. Further, it means that not only the stoichiometric composition but also the non-stoichiometric composition in which some elements are deleted or the like is included. When the above-mentioned other element substitution is performed, it is not particularly limited, but is usually 0.1 mol%, preferably 0.2 mol% or more. Further, it is usually 5 mol% or less, preferably 2.5 mol% or less.

The positive electrode active material may be used alone, or two or more kinds may be used in any combination and ratio.

(2) Surface Coating A substance having a composition different from that of the substance constituting the main positive electrode active material (hereinafter, appropriately referred to as “surface adhering substance”) is attached to the surface of the above positive electrode active material. It can also be used as a positive electrode active material in the form. Examples of surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, etc. Examples thereof include sulfates such as calcium sulfate and aluminum sulfate, and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

These surface adhering substances are, for example, dissolved or suspended in a solvent, impregnated and added to the positive electrode active material, and then dried, or the surface adhering substance precursor is dissolved or suspended in the solvent and impregnated and added to the positive electrode active material. After that, it can be adhered to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing at the same time, or the like. When carbon is attached, a method of mechanically attaching the carbon substance later in the form of activated carbon or the like can also be used.

The mass of the surface adhering substance adhering to the surface of the positive electrode active material is not particularly limited, but is usually 0.1 ppm or more, and 1 ppm or more, based on the total mass of the positive electrode active material and the surface adhering material. Preferably, 10 ppm or more is more preferable, and usually 20% by mass or less, 10% by mass or less is preferable, and 5% by mass or less is more preferable.

The surface-adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte solution on the surface of the positive electrode active material, and can improve the battery life. However, when the amount of adhesion is within the above range, the effect can be sufficiently exhibited, and the increase in resistance of the lithium battery tends to be easily suppressed.

(3) Shape The shape of the positive electrode active material particles is not particularly limited, and may be any of the conventionally used lumps, polyhedrons, spheres, elliptical spheres, plates, needles, columns and the like. Among these, those in which the primary particles are aggregated to form secondary particles and the shape of the secondary particles is spherical or elliptical spherical are preferable.

Normally, in an electrochemical element, the active material in the electrode expands and contracts with the charge and discharge, so that the stress tends to cause deterioration such as destruction of the positive electrode active material and breakage of the conductive path. Therefore, the stress of expansion and contraction can be relieved when the primary particles are aggregated to form the secondary particles, rather than the positive electrode active material which is a single particle containing only the primary particles, and therefore deterioration is less likely to occur. ..

In addition, since spherical or elliptical spherical particles have less orientation during molding of the electrode than axially oriented particles such as plate-shaped particles, the expansion and contraction of the electrode during charging and discharging is also smaller, and the electrode is created. It is also preferable to mix it with the conductive material because it is easy to mix uniformly.

(4) Tap Density Tap density positive electrode active material is not particularly limited, is usually 0.4 g · ^{cm -3} or higher, preferably 0.6 g · ^{cm -3} or more, 0.8 g · ^{cm -3} or higher more preferably, particularly preferably 1.0 g · ^{cm -3} or more, generally not more than ^{4.0g · cm -3, 3.8g · cm} -3 or less.

By using a positive electrode active material having a high tap density, a high density positive electrode active material layer can be formed. Therefore, when the tap density of the positive electrode active material is within the above range, the amount of the dispersion medium required for forming the positive electrode active material layer is appropriate, so that the required amount of the conductive material and the binder is also appropriate. Therefore, the filling rate of the positive electrode active material in the positive electrode active material layer is not restricted, and the influence on the battery capacity is reduced. Further, the higher the tap density is, the more preferable it is, and there is no particular upper limit. However, if it is less than the above range, the diffusion of lithium ions through the non-aqueous electrolyte solution as a medium in the positive electrode active material layer becomes rate-determining, and the load characteristics tend to deteriorate. In some cases.

To measure the tap density, pass a sieve with a mesh size of 300 μm, drop the sample into a tapping cell of 20 cm ³ to fill the cell volume, and then use a powder density measuring device (for example, a tap density manufactured by Seishin Enterprise Co., Ltd.). Using this, tapping with a stroke length of 10 mm is performed 1000 times, and the density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the positive electrode active material in the present invention.

(5) Median diameter d50
The median diameter d50 of the particles of the positive electrode active material (secondary particle diameter when the primary particles are aggregated to form secondary particles) can be measured using a laser diffraction / scattering particle size distribution measuring device. it can.

The median diameter d50 of the positive electrode active material is not particularly limited, but is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, and usually 20 μm or less, 18 μm. The following is preferable, 16 μm or less is more preferable, and 15 μm or less is further preferable. When the median diameter d50 is within the above range, a high bulk density product tends to be easily obtained, and lithium in the particles tends to diffuse in a short time, so that the battery characteristics are less likely to deteriorate. Further, when producing a positive electrode of a lithium battery or the like, that is, when an active material and a conductive material, a binder or the like are slurried with a solvent and applied in a thin film form, streaks or the like tend to be less likely to occur.

By mixing two or more types of positive electrode active materials having different median diameters d50 at an arbitrary ratio, the filling property at the time of producing the positive electrode can be further improved.

For the median diameter d50 of the positive electrode active material, for example, a 0.1 mass% sodium hexametaphosphate aqueous solution is used as a dispersion medium, and a particle size distribution meter (for example, LA-920 manufactured by HORIBA, Ltd.) is used to the dispersion liquid of the positive electrode active material. After 5 minutes of ultrasonic dispersion treatment, the measured refractive index can be set to 1.24 for measurement.

(6) Average primary particle size When the primary particles are aggregated to form secondary particles, the average primary particle size of the positive electrode active material is not particularly limited, but is usually 0.03 μm or more, and 0.05 μm or more. Is preferable, 0.08 μm or more is more preferable, 0.1 μm or more is further preferable, and usually 5 μm or less, 4 μm or less is preferable, 3 μm or less is more preferable, and 2 μm or less is further preferable. Within the above range, spherical secondary particles are likely to be formed, the powder filling property tends to be appropriate, and the specific surface area can be sufficiently secured, so that the output characteristics and charge / discharge reversibility are reversible. There is a tendency that deterioration of battery performance such as the above is easily suppressed.

The average primary particle size of the positive electrode active material is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles, and the average value thereof is calculated. It is required by taking.

(7) BET Specific Surface Area The BET specific surface area of the positive electrode active material is not particularly limited, but the value of the specific surface area measured by the BET method is usually 0.1 m ² · g ^-1 or more, and 0.2 m ² · ^{g -1} or more preferably, 0.3 m ² · ^{g -1} or more, and also is generally ^{50 m} 2 · ^{g -1} or less, ^{40 m} 2 · ^{g -1} or less are preferred, ^{30 m} 2 · ^{g -1} The following is more preferable. When the value of the BET specific surface area is within the above range, the deterioration of the battery performance tends to be suppressed, a sufficient tap density is secured, and the coatability at the time of forming the positive electrode active material layer tends to be good. It is in.

The BET specific surface area is measured using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura RIKEN). Specifically, the sample was pre-dried at 150 ° C. for 30 minutes under nitrogen flow, and then the nitrogen helium mixed gas was accurately adjusted so that the relative pressure value of nitrogen with respect to atmospheric pressure was 0.3. The specific surface area is measured by the nitrogen adsorption BET 1-point method by the gas flow method. The specific surface area obtained by the measurement is defined as the BET specific surface area of the positive electrode active material in the present embodiment.

(8) Method for producing positive electrode active material The method for producing the positive electrode active material is not particularly limited, and various known production methods can be applied. Preferably, several methods are mentioned, but a general method is used as a method for producing an inorganic compound.

In particular, various methods can be considered for producing spherical or elliptical spherical active materials. For example, as one example, transition metal raw materials such as transition metal nitrate and sulfate, and raw materials of other elements as necessary. Is dissolved or pulverized and dispersed in a solvent such as water, the pH is adjusted while stirring to prepare and recover a spherical precursor, which is dried as necessary, and then LiOH, Li ₂ CO ₃ , Li NO. Examples thereof include a method of adding a Li source such as ₃ and firing at a high temperature to obtain an active material.

Further, as an example of another method, a transition metal raw material such as transition metal nitrate, sulfate, hydroxide, oxide and, if necessary, a raw material of another element are dissolved or pulverized and dispersed in a solvent such as water. Then, it is dried and molded with a spray dryer or the like to form a spherical or elliptical spherical precursor, to which Li sources such as LiOH, Li ₂ CO ₃ and Li NO ₃ are added and fired at a high temperature to obtain an active material. Can be mentioned.

As an example of yet another method, transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, and oxides, Li sources such as LiOH, Li ₂ CO ₃ , and LiNO ₃ , and other elements as required. Is a method of dissolving or pulverizing and dispersing the raw material of the above in a solvent such as water, drying and molding it with a spray dryer or the like to obtain a spherical or elliptical spherical precursor, and firing this at a high temperature to obtain an active material. Can be mentioned.

<3-1-4-2. Electrode structure and manufacturing method>
The configuration of the positive electrode used in this embodiment and the method for producing the positive electrode will be described below.

(1) Method for producing a positive electrode A positive electrode is produced by forming a positive electrode active material layer containing positive electrode active material particles and a binder on a current collector. The positive electrode using the positive electrode active material can be produced by any known method. For example, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener are mixed in a dry manner to form a sheet, which is then pressure-bonded to a current collector, or these materials are used as a liquid medium. A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by dissolving or dispersing it as a slurry, applying it to a positive electrode current collector, and drying it.

The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, but is preferably 80% by mass or more, more preferably 82% by mass or more, and further preferably 84% by mass or more. The upper limit thereof is not particularly limited, but is preferably 99% by mass or less, more preferably 98% by mass or less. When it is within the above range, the battery capacity tends to be sufficiently secured, and the strength of the positive electrode tends to be secured. As the positive electrode active material powder, one type may be used alone, or two or more types having different compositions or different powder physical characteristics may be used in any combination and ratio.

(2) Conductive material As the conductive material, a known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel; graphite (graphite) such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbonaceous materials such as amorphous carbon such as needle coke. In addition, these may use 1 type alone or may use 2 or more types in arbitrary combinations and ratios.

The content of the conductive material in the positive electrode active material layer is not particularly limited, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less. It is preferably 30% by mass or less, more preferably 15% by mass or less. When the content is within the above range, the conductivity tends to be sufficiently secured, and the battery capacity tends to be sufficiently secured.

(3) Binder The binder used for producing the positive electrode active material layer is not particularly limited as long as it is a material stable to the non-aqueous electrolyte solution and the solvent used for producing the electrode.

In the case of the coating method, the binder may be a material that is dissolved or dispersed in the liquid medium used in manufacturing the electrode. Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), fluororubber, Rubber-like polymers such as isoprene rubber, butadiene rubber, ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogen additive thereof, EPDM (ethylene / propylene / diene ternary copolymer), styrene / ethylene / Thermoplastic elastomeric polymers such as butadiene / ethylene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinylidene fluoride, ethylene / vinyl acetate copolymer Soft resinous polymers such as coalesced products, propylene / α-olefin copolymers; polyvinylidene fluoride (PVdF), polyvinylidene fluoride, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers, etc. Molecular; Examples thereof include a polymer composition having ionic conductivity of alkali metal ions (particularly lithium ions). In addition, as these substances, 1 type may be used alone, and 2 or more types may be used in arbitrary combinations and ratios.

The ratio of the binder in the positive electrode active material layer is not particularly limited, but is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and usually 50% by mass or less. It is preferably 30% by mass or less, more preferably 10% by mass or less, and further preferably 8% by mass or less. When the ratio of the binder is within the above range, the positively active substance can be sufficiently retained, the mechanical strength of the positive electrode is maintained, and the decrease in cycle characteristics, battery capacity and conductivity tends to be suppressed.

(4) Liquid medium The liquid medium for forming the slurry may be a solvent capable of dissolving or dispersing a positive electrode active material, a conductive material, a binder, and a thickener used as needed. For example, the type is not particularly limited, and either an aqueous solvent or an organic solvent may be used.

Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of organic media include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methylethylketone and cyclohexanone. Classes; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine, N, N-dimethylaminopropylamine; ethers such as diethyl ether and tetrahydrofuran (THF); N-methylpyrrolidone (NMP), dimethylformamide , Amides such as dimethylacetamide; aprotonic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide can be mentioned. In addition, these may be used individually by 1 type, and may use 2 or more types by arbitrary combinations and ratios.

(5) Thickener When an aqueous medium is used as the liquid medium for forming the slurry, it is preferable to use a thickener and a latex such as styrene-butadiene rubber (SBR) to form a slurry. Thickeners are commonly used to adjust the viscosity of the slurry.

The thickener is not particularly limited, and specific examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in any combination and ratio of two or more.

When a thickener is used, the ratio of the thickener to the positive electrode active material is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 0.6% by mass. % Or more, usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Within the above range, the coatability of the slurry becomes good, the ratio of the active material to the positive electrode active material layer can be maintained, and the decrease in battery capacity and the increase in resistance between the positive electrode active materials tend to be suppressed. is there.

(6) Consolidation The positive electrode active material layer obtained by applying and drying the above slurry to the current collector is preferably consolidated by a hand press, roller press, or the like in order to increase the packing density of the positive electrode active material. .. The density of the positive electrode active material layer is preferably 1 g · cm ^-3 or more, more preferably 1.5 g · cm ^-3 or more, further preferably 2 g · cm ^-3 or more, and preferably 4 g · cm ^-3 or less. 3.5 g · cm ^-3 or less is more preferable, and 3 g · cm ^-3 or less is further preferable.

When the density of the positive electrode active material layer is within the above range, the permeability of the non-aqueous electrolyte solution to the vicinity of the current collector / active material interface is unlikely to decrease, and the decrease in charge / discharge characteristics at a high current density is suppressed. There is a tendency. In addition, the conductivity between the active materials tends to be difficult to decrease, and the battery resistance tends to be difficult to increase.

(7) Current collector The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; carbonaceous materials such as carbon cloth and carbon paper. Among these, a metal material, particularly aluminum, is preferable.

The shape of the current collector is also not particularly limited. For example, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foamed metal, etc. can be mentioned, and in the case of a carbonaceous material, a carbon plate, a carbon thin film, a carbon column, etc. Can be mentioned. Of these, a metal thin film is preferable. The thin film may be appropriately formed in a mesh shape.

The thickness of the current collector is arbitrary and is not particularly limited, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, preferably 50 μm or less. More preferred. Within the above range, sufficient strength required as a current collector can be secured, and handleability tends to be good.

The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before the electrolytic solution injection) / (thickness of the current collector) is , Usually 20 or less, preferably 15 or less, more preferably 10 or less, and the lower limit is usually 0.5 or more, preferably 0.8 or more, more preferably 1 or more. Within this range, heat generation of the current collector due to Joule heat during high current density charging / discharging can be suppressed, and the volume ratio of the current collector to the positive electrode active material is reduced, so that a decrease in battery capacity is suppressed. Tend to be.

<3-1-5. Separator>
A separator is usually interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the non-aqueous electrolyte solution of the present embodiment can be used by impregnating the separator.

The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted. Among them, it is preferable to use a resin, glass fiber, an inorganic substance or the like formed of a material stable to the non-aqueous electrolytic solution of the present embodiment, and a porous sheet or a non-woven fabric-like material having excellent liquid retention is used. Is more preferable to use.

As the material of the resin and the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyether sulfone, glass filter and the like can be used. Among these, glass filters and polyolefins are preferable, and polyolefins are more preferable. One of these materials may be used alone, or two or more of these materials may be used in any combination and ratio.

The thickness of the separator is arbitrary and is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. .. If it is within the above range, the decrease in insulation and mechanical strength tends to be suppressed, the decrease in battery performance such as rate characteristics is suppressed, and the decrease in energy density of the lithium battery as a whole is also suppressed. Tends to be.

Further, when a porous material such as a porous sheet or a non-woven fabric is used as the separator, the porosity of the separator is arbitrary and is not particularly limited, but is usually 20% or more, preferably 35% or more, preferably 45%. The above is more preferable, and usually 90% or less, 85% or less is preferable, and 75% or less is more preferable. When it is within the above range, the film resistance does not become too large and the deterioration of the rate characteristics tends to be suppressed. In addition, the mechanical strength of the separator is maintained at an appropriate level, and the deterioration of the insulating property tends to be suppressed.

The average pore size of the separator is also arbitrary and is not particularly limited, but is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If it is within the above range, a short circuit is unlikely to occur, the film resistance is not too large, and a decrease in rate characteristics tends to be suppressed.

On the other hand, examples of the inorganic material include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate. These are usually in the form of particles or fibers.

The form of the separator includes, for example, a thin film such as a non-woven fabric, a woven fabric, and a microporous film, but the form is not particularly limited. As the thin film-shaped separator, a separator having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can also be used. For example, alumina particles having a 90% particle size of less than 1 μm are used on both sides of the positive electrode, and a fluororesin is used as a binder to form a porous layer.

<3-1-6. Battery design>
[Electrode group]
The electrode group has a laminated structure in which the above-mentioned positive electrode plate and the negative electrode plate are formed by the above-mentioned separator, and a structure in which the above-mentioned positive electrode plate and the negative electrode plate are spirally wound through the above-mentioned separator. Either may be used. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is not particularly limited, but is usually 40% or more, preferably 50% or more, and usually 90% or less. , 80% or less is preferable. When the electrode group occupancy rate is within the above range, the battery capacity and the void space can be maintained relatively large, and the inside is caused by the expansion of the member due to the high temperature of the battery and the increase in the vapor pressure of the liquid component of the electrolyte. The increase in pressure can be suppressed, and the deterioration of various characteristics such as repeated charge / discharge performance as a battery and high-temperature storage tends to be suppressed.

[Current collector structure]
The current collecting structure is not particularly limited, but in order to more effectively improve the discharge characteristics by the non-aqueous electrolyte solution of the present embodiment, the structure should reduce the resistance of the wiring portion and the joint portion. Is preferable. When the internal resistance is reduced in this way, the effect of using the non-aqueous electrolyte solution of the present embodiment is particularly well exhibited.

When the electrode group has the above-mentioned laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminals is preferably used. When the area of one electrode becomes large, the internal resistance becomes large. Therefore, it is preferable to provide a plurality of terminals in the electrode to reduce the resistance. When the electrode group has the above-mentioned wound structure, the internal resistance can be reduced by providing a plurality of lead structures on the positive electrode and the negative electrode and bundling them in the terminals.

[Exterior case]
The material of the outer case is not particularly limited as long as it is a substance stable to the non-aqueous electrolyte solution used. Specific examples thereof include nickel-plated steel plates, stainless steel, aluminum or aluminum alloys, metals such as magnesium alloys, and laminated films (laminated films) of resins and aluminum foil. From the viewpoint of weight reduction, aluminum or aluminum alloy metal or laminated film is preferably used.

In the outer case using the metals, the metals are welded to each other by laser welding, resistance welding, ultrasonic welding, etc. to form a sealed and sealed structure, or a caulking structure using the metals via a resin gasket. And so on. Examples of the outer case using the laminated film include a case in which resin layers are heat-sealed to form a sealed and sealed structure. In order to improve the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when the resin layer is heat-sealed via the current collecting terminal to form a closed structure, the metal and the resin are bonded to each other. Therefore, a resin having a polar group or a modification in which a polar group is introduced as an intervening resin is introduced. Resin is preferably used.

[Protective element]
As the above-mentioned protective elements, PTC (Positive Temperature Coafficient) whose resistance increases when abnormal heat generation or excessive current flows, thermal fuse, thermistor, and current flowing in the circuit due to a sudden rise in battery internal pressure or internal temperature during abnormal heat generation. A valve that shuts off the current (current cutoff valve) and the like can be mentioned. It is preferable to select the protective element under conditions that do not operate under normal use of high current, and from the viewpoint of high output, it is more preferable to design the protective element so as not to cause abnormal heat generation or thermal runaway even without the protective element.

[Exterior body]
The lithium battery of the present embodiment is usually configured by accommodating the above-mentioned non-aqueous electrolyte solution, negative electrode, positive electrode, separator and the like inside the exterior. There is no limitation on this exterior body, and a known one can be arbitrarily adopted.

Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is used.

Further, the shape of the exterior body is also arbitrary, and may be any of, for example, a cylindrical type, a square type, a laminated type, a coin type, and a large size.

<3-2. Multivalent cation battery>
In the polyvalent cation battery of the present embodiment, an oxide material or the like is used for the positive electrode, and a metal such as magnesium, calcium or aluminum or a compound containing these metals is used for the negative electrode. The electrolyte is a non-aqueous electrolyte solution in which magnesium salts, calcium salts, aluminum salts, etc. are dissolved in a non-aqueous solvent so as to give the same elements as the reaction active material species of the negative electrode, that is, magnesium ions, calcium ions, and aluminum ions. A non-aqueous electrolyte solution for a polyvalent cation battery can be prepared by dissolving LiBF _n NCO _(4-n) therein.

<3-3. Metal-air battery ＞
In the metal-air battery of the present embodiment, a metal such as zinc, lithium, sodium, magnesium, aluminum, calcium, or a compound containing these metals is used as the negative electrode. Since the positive electrode active material is oxygen, a porous gas diffusion electrode is used for the positive electrode. Carbon is preferable as the porous material. A lithium salt, a sodium salt, a magnesium salt, an aluminum salt, a calcium salt, etc. are dissolved in a non-aqueous solvent so that the same elements as the negative electrode active material species, that is, lithium, sodium, magnesium, aluminum, calcium, etc. are given to the electrolyte. A non-aqueous electrolyte solution for a metal-air battery can be prepared by dissolving LiBF _n NCO _(4-n) in the non-aqueous electrolyte solution.

<3-4. Secondary battery using s-block metal other than the above>
The s-block element is a group 1 element (hydrogen, alkali metal), a group 2 element (berylium, magnesium and alkaline earth metal) and helium, and the s-block metal secondary battery is described above. It means a secondary battery using an s-block metal as a negative electrode and / or an electrolyte. Specific examples of the s-block metal secondary battery other than the above include a lithium-sulfur battery and a sodium-sulfur battery using sulfur for the positive electrode, a sodium ion battery, and the like.

<3-5. Lithium ion capacitor ＞
A material capable of forming an electric double layer is used for the positive electrode, and a material capable of occluding and releasing lithium ions is used for the negative electrode. Activated carbon is preferable as the amount of the positive electrode material. Further, as the negative electrode material, a carbonaceous material is preferable. As the non-aqueous electrolyte solution, a non-aqueous electrolyte solution containing LiBF _n NCO _(4-n) is used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Reference Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.

(Example 1)
[Preparation of LiBF _n (NCO) _4-n : mean value of n = 3]
-Preparation of LiOCN 1.53 g (120 mol) of Li ₂ SO ₄ · H ₂ O was dissolved in 5 ml of pure water, and the obtained solution was dissolved in 1.62 g (200 mmol) of KOCN in 5 ml of pure water. The mixture was mixed with the solution and the precipitated K ₂ SO ₄ was filtered off. After stirring for about 30 minutes, 500 ml of ethanol was directly added to this aqueous solution to stir, and the precipitated salt was filtered off. Then, the hydrous ethanol was once distilled off from the ethanol solution containing water, and the temperature was 45 ° C. for 8 hours. It was vacuum dried to obtain a white powder. This white powder was dissolved again in 500 ml of dry ethanol, the insoluble material was strained, ethanol was distilled off, and the mixture was vacuum dried at 45 ° C. for about 8 hours to obtain LiOCN.
As a result of IC analysis, 99% or more of the cation species were Li ⁺ , and no anion species other than OCN ⁻ were detected.

-Mixing with BF ₃ / Et ₂ O complex In a PFA flask, 49 mg (10 mmol) of LiOCN was suspended in 10 ml of acetonitrile, and 126 mg (10 mmol) of a commercially available BF ₃ / Et ₂ O complex was slowly added dropwise. With continued stirring, the precipitate was significantly reduced. After the insoluble matter was filtered off, a light boiling material such as a solvent was distilled off to obtain a white powder.

FIG. 1 shows the results of ¹⁹ F-NMR measurement. Further, FIG. 2 shows the ¹¹ B-NMR measurement results. ^{19 In the} F-NMR measurement, signals of BF ₄ , BF ₃ (NCO) anion and an anion having a BF bond presumed to be BF ₂ (NCO) ₂ anion were observed, and B- on the low magnetic field side. A slight signal was observed suggesting the inclusion of trace amounts of compounds with F-bonds. ¹¹ This result is also supported by the B-NMR measurement results.
FIG. 3 shows the ESI-MS measurement results. From this ESI-MS measurement result, it can be seen that BF ₄ , BF ₃ (NCO), BF ₂ (NCO) ₂ , BF (NCO) ₃ , and B (NCO) ₄ are detected as anion species.

From these results and the ¹⁹ F-NMR integration ratio, the white powder obtained contained a ratio of LiBF ₄ : LiBF ₃ (NCO): LiBF ₂ (NCO) ₂ ≈20: 40: 20, and further LiBF (NCO). It was suggested that the sample contained a small amount of ₃ and LiB (NCO) ₄ . This sample was designated as lithium salt A.

[Preparation of negative electrode]
98 parts by mass of carbonaceous material, 1 part by mass of aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose 1% by mass) and aqueous dispersion of styrene-butadiene rubber (of styrene-butadiene rubber) as a thickener and binder. (Concentration 50% by mass) 1 part by mass was added and mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and rolled with a press to prepare a laminated plate in which a negative electrode active material layer was provided on the copper foil. From this laminated board, a section having a negative electrode active material layer having a width of 30 mm and a length of 40 mm and an uncoated portion having a width of 5 mm and a length of 9 mm was cut out to obtain a negative electrode.

[Preparation of positive electrode]
90% by mass of Li (Ni _1/3 Mn _1/3 Co _1/3 ) O ₂ (LNMC) as a positive electrode active material, 5% by mass of acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder. ) 5% by mass was mixed in an N-methylpyrrolidone solvent to form a slurry. The obtained slurry was applied to one side of a 15 μm-thick aluminum foil coated with a conductive auxiliary agent in advance, dried, rolled and pressed with a press machine, and laminated with a positive electrode active material layer provided on the aluminum foil. A board was made. A section having a positive electrode active material layer having a width of 30 mm and a length of 40 mm and an uncoated portion having a width of 5 mm and a length of 9 mm was cut out from this laminated plate to obtain a positive electrode.

[Preparation of electrolyte]
In a dry argon atmosphere, add 1 mol / L of dried LiPF ₆ to a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio 30:30:40). The basic electrolyte was prepared by dissolving in. The non-aqueous electrolyte solution of Example 1 was prepared by adding 0.5% by mass of the lithium salt A to the basic electrolyte solution with respect to the total amount of the non-aqueous electrolyte solution.

[Manufacturing of lithium secondary batteries]
The above positive electrode, negative electrode, and polyethylene separator were laminated in this order of the negative electrode, the separator, and the positive electrode to prepare a battery element. After inserting this battery element into a bag made of a laminated film in which both sides of aluminum (thickness 40 μm) are coated with a resin layer while projecting the positive electrode and negative electrode terminals, the non-aqueous electrolyte solution is injected into the bag. , Vacuum-sealed to produce a sheet-shaped lithium secondary battery of Example 1, which is fully charged at 4.2 V.

[Run-in]
A lithium secondary battery is charged to 4.2 V at 25 ° C. with a constant current equivalent to 0.2 C in a state of being sandwiched between glass plates in order to improve adhesion between electrodes, and then a constant current of 0.2 C. Was discharged to 3.0V. This is performed for two cycles to stabilize the battery, and in the third cycle, the battery is charged to 4.2 V with a constant current of 0.2 C, and then charged with a constant voltage of 4.2 V until the current value reaches 0.05 C. , 0.2C constant current discharged to 3.0V. This was performed for two cycles to complete the break-in operation.

[Evaluation of initial -30 ° C output characteristics]
The battery for which the evaluation of the initial discharge capacity was completed was charged at 25 ° C. with a constant current of 0.2 C so as to have a capacity half of the initial discharge capacity. This was discharged at 0.5C, 1.0C, 1.5C, 2.0C and 2.5C at −30 ° C., and the voltage at 10 seconds was measured. The current value at 3.0 V was obtained from the current-voltage straight line, and 3.0 × (current value at 3.0 V) was taken as the output (W). Table 1 shows the relative values (%) when the initial output of Comparative Example 1 is 100.

[Evaluation of initial -30 ° C input characteristics]
The battery for which the evaluation of the initial discharge capacity was completed was charged at 25 ° C. with a constant current of 0.2 C so as to have a capacity half of the initial discharge capacity. This was charged at 0.5C, 1.0C, 1.5C, 2.0C and 2.5C at −30 ° C., and the voltage at 10 seconds was measured. The current value at 4.2 V was obtained from the current-voltage straight line, and 4.2 × (current value at 4.2 V) was taken as the output (W). Table 1 shows the relative value (%) when the initial input of Comparative Example 1 is 100.

[Evaluation of cycle characteristics]
Among the batteries whose initial discharge capacity has been evaluated, the batteries whose initial output and initial input both exceed 80% are charged to 4.2V with a constant current of 2.0C, and then have a constant current of 2C. Was discharged to 3.0V. This was carried out at 60 ° C. for 500 cycles. The cycle discharge capacity retention rate (%) was obtained from [(discharge capacity in the 500th cycle) ÷ (discharge capacity in the first cycle)] × 100. Table 1 shows the relative value (%) when Comparative Example 1 is 100.0.

[Evaluation of -30 ° C output characteristics after cycle]
The battery for which the evaluation of the initial discharge capacity was completed was charged at 25 ° C. with a constant current of 0.2 C so as to have a capacity half of the initial discharge capacity. This was discharged at 0.5C, 1.0C, 1.5C, 2.0C and 2.5C at −30 ° C., and the voltage at 10 seconds was measured. The current value at 3.0 V was obtained from the current-voltage straight line, and 3.0 × (current value at 3.0 V) was taken as the output (W). Table 1 shows the relative values (%) when the initial output of Comparative Example 1 is 100.

[Evaluation of -30 ° C input after cycle]
The battery for which the evaluation of the cycle test was completed was charged at 25 ° C. with a constant current of 0.2 C to half the capacity of the initial discharge capacity. This was charged at 0.5C, 1.0C, 1.5C, 2.0C and 2.5C at −30 ° C., and the voltage at 10 seconds was measured. The current value at 4.2 V was obtained from the current-voltage straight line, and 4.2 × (current value at 4.2 V) was used as the input (W). Table 1 shows the relative value (%) when the initial input of Comparative Example 1 is 100.

(Comparative Example 1)
A sheet-shaped lithium secondary battery of Comparative Example 1 was produced and evaluated in the same manner as in Example 1 except that the above-mentioned basic electrolytic solution was used instead of the non-aqueous electrolyte solution of Example 1. The results are shown in Table 1.

(Comparative Example 2)
Example 1 except that, instead of the non-aqueous electrolyte solution of Example 1, a non-aqueous electrolyte solution containing 0.5% by mass of LiBF ₄ with respect to the total amount of the non-aqueous electrolyte solution is used in the above-mentioned basic electrolyte solution. In the same manner as in the above, a sheet-shaped lithium secondary battery of Comparative Example 2 was produced and evaluated. The results are shown in Table 1.

(Comparative Example 3)
Same as Example 1 except that a non-aqueous electrolyte solution containing 0.5% by mass of lithium (oxalate) borate (LiBOB) is used in the above-mentioned basic electrolyte solution instead of the non-aqueous electrolyte solution of Example 1. Then, the sheet-shaped lithium secondary battery of Comparative Example 3 was prepared and evaluated. The results are shown in Table 1.

As is clear from Table 1, Example 1 containing the lithium salt A of the present invention has an initial output, an initial input, a post-cycle output, and a post-cycle input as compared with Comparative Example 1 and Comparative Example 2 not containing the lithium salt A. , And all items of cycle capacity retention rate are excellent. In particular, the non-aqueous electrolyte solution containing lithium salt A is superior to the lithium salt containing a boron atom in the anion structure as in the case of lithium salt A, and therefore, the lithium salt of the present invention is excellent in each of the above characteristics. And the usefulness of the non-aqueous electrolyte solution using this was shown.

As described in detail above, although the present invention has been described in detail and with reference to specific embodiments, it is possible that the present invention may be modified or modified without departing from the spirit and scope of the invention. Obvious to those skilled in the art.

The lithium salt of the present invention can be widely and effectively used in general electrolyte applications that can improve the cycle capacity retention rate of power storage devices such as lithium batteries and the input / output characteristics after the cycle. Further, the non-aqueous electrolyte solution of the present invention and a power storage device such as a lithium battery using the same can be used for various known applications. Specific examples include, for example, laptop computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile fax machines, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini discs. , Transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, bikes, motorized bicycles, bicycles, lighting equipment, toys, game equipment, watches, power tools, strobes, cameras, homes Examples include a backup power supply for business use, a backup power supply for business establishments, a power supply for load leveling, a natural energy storage power supply, and a lithium ion capacitor.

Claims (4)

Includes a compound represented by a following general formula (1) at least one or more, the total content of the compound represented by the general formula (1) is 5 mass% or less than 0.01 mass%, further the general It contains one or more electrolyte salts different from the compound represented by the formula (1), and the other electrolyte salts are inorganic lithium salts, fluorophosphate lithium salts, sulfonic acid lithium salts, lithiumimide salts, lithium oxalates. comprises at least one selected from the group consisting of salts, Ri total content of 8% by mass to 18% by mass or less of the further electrolyte salt, wherein the inorganic lithium salt is _{LiBF 4, LiClO 4, LiAlF 4} , LiSbF 6 , LiTaF _6, non-aqueous electrolyte, wherein at least one der Rukoto of LiWF _7.
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 3 or less.) The first aspect of the present invention is characterized in that it contains two or more compounds represented by the following general formula (1) and the average value m of the isocyanato substitution number 4-n is 0.1 to 3.9. The non-aqueous electrolyte solution described.
LiBF _n (NCO) _4-n ... (1)
(In the formula, n represents an integer of 0 or more and 4 or less.) The non-aqueous electrolyte solution according to claim 1 or 2 , further containing a cyclic carbonate containing at least one of a carbon-carbon unsaturated bond and a fluorine atom. A power storage device containing the non-aqueous electrolyte solution according to any one of claims 1 to 3 .