JP2020095956A - Nonaqueous electrolytic secondary battery - Google Patents

Abstract

To provide a nonaqueous electrolytic secondary battery superior in the balance between a discharge capacity and a discharge rate characteristic after a charge-discharge cycle.SOLUTION: A nonaqueous electrolytic secondary battery comprises a nonaqueous electrolyte containing a nonaqueous solvent and a mass% of a compound represented by the formula (1), and a negative electrode containing b mass% of SiOx in a negative electrode active material, in which 0.05≤a/b≤1.50 is satisfied.(In the formula (1), Rand Rrepresent a hydrogen atom, an alkyl group with 1-5 carbon atoms, which may have a halogen atom, or an aryl group with 6-10 carbon atoms, which may have a halogen atom; n is 0 or 1; and p is 0 or 1.)SELECTED DRAWING: None

Description

The present invention relates to a non-aqueous electrolyte secondary battery. More specifically, the present invention relates to a non-aqueous electrolyte secondary battery having an excellent balance of discharge capacity after discharge/charge cycles and discharge rate characteristics.

Non-aqueous electrolyte secondary batteries such as lithium secondary batteries have been put to practical use in a wide range of applications such as power sources for mobile phones, laptop computers, in-vehicle power sources for automobiles, large stationary power sources, and the like. However, in recent years, the demand for higher performance of non-aqueous electrolyte secondary batteries is increasing, and after achieving high energy density, input/output characteristics, cycle characteristics, storage characteristics, continuous charging characteristics, safety It is required to achieve various battery characteristics such as battery performance at a high level.

Until now, attempts have been made to use a metal or a metal oxide that can be alloyed with lithium as a negative electrode active material for the purpose of increasing the capacity of a non-aqueous electrolyte secondary battery. However, it is known that a compound that can be alloyed with lithium is prone to deterioration of the battery because it undergoes a large volume change during charge and discharge. In recent years, among compounds capable of alloying with lithium,
As a negative electrode active material having a relatively small change in volume, SiOx has attracted attention.

Further, it has been previously proposed to use an additive for a non-aqueous electrolyte solution in order to improve battery characteristics such as cycle characteristics of the non-aqueous electrolyte secondary battery. In particular, it is known that an additive having a phosphonic acid diester structure has excellent performance. For example, in Patent Document 1, by containing bis(2,2,2-trifluoroethyl)phosphonate in a non-aqueous electrolyte,
A technique capable of improving high temperature durability is disclosed. It is also known that an additive having a phosphonic acid diester in which a hydrogen atom is substituted or a phosphinic acid ester structure also has excellent performance. For example, Patent Document 2 discloses a technique capable of improving cycle characteristics and the like by containing a phosphonic acid diester or a phosphinic acid ester substituted with an alkyl group or an aryl group in a non-aqueous electrolyte solution. Further, Patent Document 3 discloses a technique capable of improving high-temperature storage characteristics and gas characteristics by containing a phosphonic acid diester substituted with a functional group having an ester bond in a non-aqueous electrolyte solution.

JP, 2014-146517, A JP, 2007-299542, A JP, 2014-194930, A

According to the verification by the present inventors, the problems of the technologies of Patent Documents 1 to 3 described above are insufficient balance between capacity after cycling and rate characteristics. As a result of studies conducted by the present inventors, it has been found that high capacity can be achieved by using SiOx or Si as a negative electrode active material, but on the other hand, cycle characteristics and discharge rate characteristics deteriorate.
The present invention has been made in view of the background art described above, and by combining a negative electrode active material containing SiOx and an additive having a specific structure in a specific ratio, the capacity and rate characteristics after charge/discharge cycles are combined. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery having an excellent balance of

The present inventor has conducted extensive studies in order to solve the above problems, and as a non-aqueous electrolyte secondary battery, contains a specific phosphorus-containing ester compound as a non-aqueous electrolyte and contains Si in the negative electrode active material.
It has been found that the above problem can be solved by using a material containing Ox and having a phosphorus-containing ester compound content and a SiOx content satisfying a specific relationship. That is, the gist of the present invention is as follows.

[1] A non-aqueous electrolytic secondary battery comprising a non-aqueous electrolytic solution, a negative electrode and a positive electrode, wherein the negative electrode contains Si, wherein the non-aqueous electrolytic solution is a non-aqueous solvent and a compound represented by the following formula (1). Contains (1),
The negative electrode contains an active material represented by SiOx (0.5≦x≦1.6), and the content of the compound (1) in the whole non-aqueous electrolyte solution is a mass %, based on the whole negative electrode active material. A non-aqueous electrolytic secondary battery satisfying 0.05≦a/b≦1.50 when the content of SiOx is b mass %.

(In the above formula (1), R ¹ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, or an alkyl group having 6 to 10 carbon atoms which may have a halogen atom. Represents an aryl group, and R ² represents a hydrogen atom, a halogen atom, or a carbon atom which may have a halogen atom.
5 represents an alkyl group having 5 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms which may have a halogen atom, or a group represented by the following formula (2), n is 0 or 1, and p is 0 or 1. is there. )

(In the formula (2), R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, and q is 1 to 5.)

[2] R ¹ in the above formula (1) is a trifluoroethyl group, and p is 1, [
[1] The non-aqueous electrolyte solution described in [1].

[3] As the compound (1), bis(2,2,2-trifluoroethyl)phosphonate, bis(2,2,2-trifluoroethyl)methylphosphonate, bis(2,2,2-trifluoro) [1] or [2] containing at least one selected from the group consisting of ethyl)methyl phosphonoacetate and ethyl [bis(2,2,2-trifluoroethoxy)phosphinyl]acetate.
The non-aqueous electrolyte solution described in.

[4] The content of the compound (1) is 0.01% by mass or more and 10% by mass or less, [1] to [1]
[3] The non-aqueous electrolyte solution according to [3].

[5] The non-aqueous electrolyte solution according to any one of [1] to [4], wherein the content of SiOx in the negative electrode active material is 0.01% by mass or more and 15% by mass or less.

[6] The negative electrode contains an active material containing a carbon material as a main component, and the content in the negative electrode active material is 85.0% by mass or more and 99.9% by mass or less. The non-aqueous electrolyte solution according to [5].

According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery having an excellent balance of discharge capacity and discharge rate characteristics after charge/discharge cycles.

Hereinafter, the present invention will be described in detail. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. Further, the present invention can be implemented by being arbitrarily modified within the scope of the invention.

[Non-aqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery including a non-aqueous electrolyte solution, a negative electrode and a positive electrode, wherein the non-aqueous electrolyte solution is represented by a non-aqueous solvent and a formula (1) described below. The compound containing the compound (1), the negative electrode contains an active material represented by SiOx (0.5≦x≦1.6), and the content of the compound (1) in the whole non-aqueous electrolyte is a mass %, When the content of SiOx with respect to the entire negative electrode active material is b mass %, 0.05≦a/b≦1.5 is satisfied. More specifically, it is preferable that 0.05≦a/b≦1.0. When the content ratio a/b of the compound (1) and SiOx is within the above range, the effect of the compound (1) on SiOx is likely to be exhibited.

INDUSTRIAL APPLICABILITY The non-aqueous electrolyte secondary battery of the present invention has the effect of being excellent in the balance between the discharge capacity after the charge/discharge cycle and the discharge rate characteristics, even though the negative electrode active material containing SiOx is used. The reason why the present invention exerts such an effect is not clear, but it is presumed to be due to the following reason. That is, it is presumed that the compound represented by the formula (1) causes a specific reaction with SiOx contained in the negative electrode under a constant potential to form a good interface on the SiOx surface. Usually, in a non-aqueous electrolyte secondary battery using SiOx as a negative electrode active material, SiOx is repeatedly charged and discharged.
When the electrolytic solution causes an irreversible reaction and the SiOx interface is altered, cycle characteristics and rate characteristics are deteriorated. It is presumed that the good interface of the SiOx surface generated by the compound (1) suppresses the side reaction with the electrolytic solution that occurs during the charge/discharge process, and thus suppresses the previous deterioration. At this time, the compound (1) needs to be modified by reacting with the entire surface of SiOx capable of causing a side reaction with the electrolytic solution. Therefore, the compound (1) may be added to the electrolytic solution depending on the content of SiOx in the negative electrode active material. It must be contained sufficiently. On the other hand, when an excessive amount of the compound (1) is contained with respect to the content of SiOx, a large amount of the compound (1) is reductively decomposed on the negative electrode to form a thick film, and the SiOx is formed in the negative electrode. Also, the conductive paths of other active materials are easily broken, and various battery characteristics such as cycle characteristics and rate characteristics are deteriorated. That is, the optimum value of the content of the compound (1) in the electrolytic solution depends on the content of SiOx in the negative electrode active material, and each content is excellent only in the range of a specific combination. It is estimated to be effective.

<1. Non-aqueous electrolyte>
The non-aqueous electrolytic solution used in the present invention contains a non-aqueous solvent and a compound (1) represented by the following formula (1) in a mass% and the content of SiOx in the negative electrode active material is b mass%: 0.05≦a/
It satisfies b≦1.5.

(In the above formula (1), R ¹ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, or an alkyl group having 6 to 10 carbon atoms which may have a halogen atom. Represents an aryl group, and R ² represents a hydrogen atom, a halogen atom, or a carbon atom which may have a halogen atom.
5 represents an alkyl group having 5 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms which may have a halogen atom, or a group represented by the following formula (2), n is 0 or 1, and p is 0 or 1. is there. )

(In the formula (2), R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, and q is 1 to 5.)

<1-1. Compound (1)>
The non-aqueous electrolyte used in the present invention contains the compound represented by the formula (1).
Specifically, it has a P-OCH ₂ CF ₃ structure. It is known that the organic phosphate ester reacts with the oxide surface, but it is considered that the compound (1) also undergoes a specific reaction with the surface even with respect to the negative electrode active material SiOx, and reforms to a good interface. .. In order to react with the SiOx surface, it is necessary to disperse a large amount of compound (1) in the vicinity of the SiOx surface, but by having a trifluoroethyl group capable of overhanging the electronegative fluorine atom on the molecular surface, Compound (1) on SiOx surface
Is adsorbed, which facilitates the progress of surface modification. For the above reasons, it is considered that the compound (1) having the P-OCH2CF3 structure exerts a good effect in the battery using the negative electrode active material containing SiOx. In the above formula (1), R ¹ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, or a carbon atom having 6 to 6 carbon atoms which may have a halogen atom.
10 represents an aryl group, R ² is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, or an aryl group having 6 to 10 carbon atoms which may have a halogen atom. Represents a group or a group represented by the above formula (2), n is 0 or 1, and p is 0 or 1. In the formula (2), R ³ is a hydrogen atom or a carbon atom which may have a halogen atom
5 represents an alkyl group, and q is 1 to 5. Here, examples of the halogen atom include fluorine, chlorine, iodine, and bromine, and among these, fluorine is preferable.

In particular, in the compound (1), R ¹ is preferably a C 1-5 alkyl group optionally having a hydrogen atom or a halogen atom, and a C 1-5 alkyl group containing a fluorine atom. Is more preferable, and a trifluoroethyl group is still more preferable. This is because the above functional group easily interacts with the SiOx surface, and a large amount of the compound (1) can be unevenly distributed. R ² has a hydrogen atom or a halogen atom, and may have 1 to 5 carbon atoms.
And an alkyl group represented by the formula (2) are preferable. In the formula (2), R ³ is preferably an alkyl group having 1 to 3 carbon atoms which may have a halogen atom, and q is preferably 1 to 3. Further, n is preferably 1. Also, p
Is preferably 1. This is because when the above functional group is used, the balance between the strength of interaction with the SiOx surface and the size of steric hindrance around the phosphorus atom, which is the reaction center, is excellent.

More specifically, among the compounds represented by the formula (1), phosphonic acid bis(2,2,2
2-trifluoroethyl), bis(2,2,2-trifluoroethyl)methylphosphonate, methyl bis(2,2,2-trifluoroethyl)phosphonoacetate and [bis(2,2,2
It is preferable to include at least one selected from the group consisting of 2-trifluoroethoxy)phosphinyl]ethyl acetate.

When the content of the compound represented by the formula (1) in the non-aqueous electrolyte solution is expressed as a mass %, 0.05≦a/based on the content b mass% of SiOx in the negative electrode active material. There is no particular limitation as long as it satisfies b≦1.50. As a preferable range of the content a of this compound alone,
0.01≦a≦10 is preferable, 0.01≦a≦5 is more preferable, and 0.2≦a≦3.5 is further preferable. When the content a of this compound is within the above range, the effects on the discharge capacity and the discharge rate characteristics after the charge/discharge cycle are more easily exhibited without impairing the performance of other batteries. Nuclear magnetic resonance analysis is mentioned as a measuring method of the content of the compound represented by Formula (1) in a non-aqueous electrolyte solution.

<1-2. Non-aqueous solvent>
The non-aqueous electrolyte used in the present invention usually contains, as a main component, a non-aqueous solvent that dissolves an electrolyte to be treated later, like a general non-aqueous electrolyte. The non-aqueous solvent used here is not particularly limited, and a known organic solvent can be used. The organic solvent preferably includes at least one selected from saturated cyclic carbonates, chain carbonates, chain carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds, but is not particularly limited thereto. .. These can be used alone or in combination of two or more.

<1-3-1. 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 them, ethylene carbonate and propylene carbonate are preferable from the viewpoint of improving the battery characteristics resulting from the improvement in the degree of lithium ion dissociation. As the saturated cyclic carbonate, one kind may be used alone, and two kinds or more may be used together in any combination and ratio.

The content of the saturated cyclic carbonate is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired, but the lower limit of the content when one type is used alone is usually 100% by volume of the non-aqueous solvent, It is at least 3% by volume, preferably at least 5% by volume. By setting this range, it is possible to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte solution, and to improve the large current discharge characteristics of the non-aqueous electrolyte secondary battery, the stability against the negative electrode, and the cycle characteristics. It becomes easy to set the range. The upper limit is usually 90% by volume or less, preferably 85% by volume or less, more preferably 80% by volume or less. By setting this range, the viscosity of the non-aqueous electrolyte solution can be adjusted to an appropriate range, the decrease in ionic conductivity can be suppressed, and the input/output characteristics of the non-aqueous electrolyte secondary battery can be further improved, and the cycle characteristics and storage characteristics can be improved. It is preferable because durability such as characteristics can be further improved.

<1-3-2. Chain carbonate>
The chain carbonate preferably has 3 to 7 carbon atoms. Specifically, carbon number 3 to
As the chain carbonate of 7, dimethyl carbonate, diethyl carbonate, di-n
-Propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate,
Examples thereof include ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate and t-butyl ethyl carbonate. Among these, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate,
Methyl-n-propyl carbonate is preferable, and dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are particularly preferable.

Further, chain carbonates having a fluorine atom (hereinafter, "fluorinated chain carbonate"
May be abbreviated. ) 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, and 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 ethylmethyl carbonate derivative, a fluorinated diethyl carbonate derivative and the like.

As the chain carbonate, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
Although the content of the chain carbonate is not particularly limited, it is usually 15% in 100% by volume of the non-aqueous solvent.
It is at least volume%, preferably at least 20 volume%, more preferably at least 25 volume%.
Further, it is usually 90% by volume or less, preferably 85% by volume or less, 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 is set to an appropriate range, the decrease of the ionic conductivity is suppressed, and the input/output characteristics and charge/discharge of the non-aqueous electrolyte secondary battery are suppressed. It is easy to set the rate characteristic in a good range. Further, it is possible to avoid a decrease in electric conductivity due to a decrease in dielectric constant of the non-aqueous electrolyte solution, and it is easy to set the input/output characteristics and the charge/discharge rate characteristics of the non-aqueous electrolyte secondary battery in a good range.

<1-3-3. 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, propionic acid-n
-Butyl, isobutyl propionate, -t-butyl propionate, methyl butyrate, ethyl butyrate, -n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, isobutyrate -n-propyl, isopropyl isobutyrate and the like. Be done. Among these, methyl acetate, ethyl acetate, acetic acid-n-propyl, acetic acid-n-butyl, methyl propionate, ethyl propionate, propionic acid-n-propyl, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. It is preferable from the viewpoint of improving the ionic conductivity due to the decrease and suppressing the battery swelling during the durability test such as cycle and storage.

<1-3-4. 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 the battery characteristics resulting from the improvement in the degree of lithium ion dissociation.

<1-3-5. 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.
As the chain ether having 3 to 10 carbon atoms, diethyl ether, di(2-fluoroethyl)ether, di(2,2-difluoroethyl)ether, di(2,2,2-trifluoroethyl)ether, 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 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-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)
3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy(2-fluoroethoxy)methane, methoxy(
2,2,2-trifluoroethoxy)methane methoxy(1,1,2,2-tetrafluoroethoxy)methane, diethoxymethane, ethoxy(2-fluoroethoxy)methane, ethoxy(2,2,2-trifluoro (Ethoxy)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)methane di(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)ethane, methoxy(2,
2,2-trifluoroethoxy)ethane, methoxy(1,1,2,2-tetrafluoroethoxy)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-trifluoroethoxy)ethane, (2,2,2-trifluoroethoxy)(1,1,2,2-tetrafluoroethoxy)ethane, Examples include di(1,1,2,2-tetrafluoroethoxy)ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

As the cyclic ether, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-
Methyl-1,3-dioxane, 1,4-dioxane, and the like, and fluorinated compounds thereof may be mentioned. Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvating ability to lithium ions and dissociate lithium ions. Is preferable in terms of improving Dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferable because they have low viscosity and high ionic conductivity.

<1-3-6. Sulfone compounds>
As the sulfone compound, 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 which are monosulfone compounds, tetramethylene sulfones and hexamethylene sulfones; trimethylene disulfones which are disulfone compounds, tetramethylene disulfones and hexamethylene disulfones. Among these, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable, from the viewpoint of dielectric constant and viscosity.

As the sulfolanes, sulfolane and/or sulfolane derivatives (hereinafter, sometimes also referred to as "sulfolanes" including sulfolane) are preferable. The sulfolane derivative is preferably a sulfolane derivative in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group.
Among these, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluoro Sulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3 -Methylsulfolane, 4-fluoro-2-methylsulfolane, 5-
Fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane,
3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 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 of high ionic conductivity and high input/output.

As the chain sulfone, 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, n- Butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl 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, 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-
Examples thereof include n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone and pentafluoroethyl-t-butyl sulfone.

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 , Ethyldifluoromethylsulfone, ethyltrifluoromethylsulfone, ethyltrifluoroethylsulfone, ethylpentafluoroethylsulfone, trifluoromethyl-n-propylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-butylsulfone, trifluoro Ethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, trifluoromethyl-t-butyl sulfone and the like are preferable because of high ionic conductivity and high input/output.

<1-4. Electrolyte>
The non-aqueous electrolytic solution used in the present invention usually contains an electrolyte. In particular, when the non-aqueous electrolyte secondary battery provided by the present invention is a lithium ion secondary battery, it usually contains a lithium salt.
Examples of the lithium salt that can be used in the non-aqueous electrolyte solution used in the present invention include Li
_{ClO 4, LiBF 4, LiPF 6} , LiAsF 6, LiTaF 6, LiCF 3 SO 3,
_{LiC 4 F 9 SO 3, Li} (FSO 2) 2 N, Li (CF 3 SO 2) 2 N, Li (C 2 F
₅ SO ₂ ) ₂ N, Li(CF ₃ )SO ₂ ) ₃ C, LiBF ₃ (C ₂ F ₅ ), LiB(C _{2
O 4) 2, LiB (C} 6 F 5) 4, LiPF 3 (C 2 F 5) 3 and the like. Of these, preferred are LiPF ₆ , LiBF ₄ , LiClO ₄ , and Li(FSO ₂ ) ₂ N.
And Li(CF ₃ SO ₂ ) ₂ N, and more preferably at least one selected from LiPF ₆ , LiBF ₄ , Li(FSO ₂ ) ₂ N and Li(CF ₃ SO ₂ ) ₂ N. It is one and more preferable is at least one of LiPF ₆ and Li(FSO ₂ ) ₂ N, and LiPF ₆ is particularly preferable. The lithium salts listed above may be used alone or in combination of two or more.

The concentration of the electrolyte such as a lithium salt in the final composition of the non-aqueous electrolytic solution used in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 0.5 mol/L or more, It is preferably at least 0.6 mol/L, more preferably 0.7 mol/L
On the other hand, it is preferably 3 mol/L or less, more preferably 2 mol/L or less, and further preferably 1.8 mol/L or less. When the content of the lithium salt is within the above range, the ionic conductivity can be appropriately increased.
The method for measuring the content of the above-mentioned lithium salt is not particularly limited, and any known method can be used. Examples of such a method include ion chromatography and F magnetic resonance spectroscopy.

<1-5. Other additives>
The non-aqueous electrolytic solution used in the present invention, in addition to the various compounds listed above, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, cyano such as dodecanedinitrile. Group-containing compound, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-
Bis(isocyanatomethyl)cyclohexane, 1,3-phenylene diisocyanate, 1
, 4-phenylene diisocyanate, 1,2-bis(isocyanatomethyl)benzene, 1
,3-bis(isocyanatomethyl)benzene, 1,4-bis(isocyanatomethyl)benzene and other isocyanato compounds, acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride, benzoic acid Anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3
,4,5,6-Pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride, succinic anhydride, maleic anhydride and other carboxylic anhydride compounds, vinylene carbonate, vinyl ethylene carbonate and other unsaturated bonds A cyclic carbonate having, a sulfonate compound such as 1,3-propane sultone, a phosphate such as lithium difluorophosphate, and a sulfonate such as lithium fluorosulfonate may be added. However, the lithium difluorophosphate and lithium fluorosulfonate listed here correspond to lithium salts, but are not treated as an electrolyte from the viewpoint of the degree of ionization with respect to the non-aqueous solvent used in the non-aqueous electrolytic solution, and the additive is used. Shall be positioned. Further, as an overcharge inhibitor, various additives such as cyclohexylbenzene, t-butylbenzene, t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, a partially hydrogenated terphenyl, diphenyl ether, dibenzofuran, etc. are used. Can be blended within a range that does not significantly impair These compounds may be used in appropriate combination. Among these, vinylene carbonate, lithium difluorophosphate and lithium fluorosulfonate are particularly preferable from the viewpoint of capacity retention rate, and it is particularly preferable to use these in combination.

<2. Negative electrode>
The negative electrode used in the present invention contains an active material represented by SiOx (0.5≦x≦1.6) in an amount of b% by mass.
When the content of the compound (1) in the non-aqueous electrolyte is a mass%, 0.05≦a/b≦
It satisfies 1.5.

<2-1. SiOx>
The negative electrode used in the present invention contains SiOx (0.5≦x≦1.6). X in SiOx
Is more preferably 0.7 to 1.3, and particularly preferably 0.8 to 1.2. When x is in the above range, it becomes a highly active amorphous SiOx in which alkali ions such as Li ions easily enter and leave.
As a method for measuring x in SiOx in the negative electrode active material, Si by an inductively coupled plasma emission spectrometry or molybdenum blue absorptiometry of an aqueous solution obtained by melting alkali or dilute hydrofluoric acid.
And quantitative analysis of O by an oxygen-nitrogen-hydrogen analyzer or an oxygen-nitrogen analyzer.

Further, SiOx may be doped with an element other than Si and O. SiOx doped with an element other than Si and O is expected to improve initial charge/discharge efficiency and cycle characteristics due to stabilization of the chemical structure inside the particles. The element to be doped can be selected from any element as long as it is an element other than Group 18 of the periodic table. However, S doped with an element other than Si and O can be selected.
In order for iOx to be more stable, elements up to the 4th period of the periodic table are preferable. Specifically, alkali metals, alkaline earth metals, Al, Ga, Ge, N, P, As of the 4th period of the periodic table.
, Se, etc. can be selected. In order to improve the lithium ion acceptability of SiOx doped with an element other than Si and O, the doped element is preferably an alkali metal or alkaline earth metal up to the 4th period of the periodic table, and Mg, Ca and Li are more preferable, and Li is even more preferable. These may be used alone or in combination of two or more. The SiOx particles may be composite type SiOx particles having a carbon layer made of amorphous carbon on at least a part of the surface. Here, "having a carbon layer made of amorphous carbon on at least a part of the surface" means not only a form in which the carbon layer covers part or all of the surface of the silicon oxide particles in a layered manner, but It also includes a form in which it is attached or attached to part or all of the surface. The carbon layer may be provided so as to cover the entire surface, or a part thereof may be covered or attached/adhered.

When the content of SiOx (0.5≦x≦1.6) in the active material is expressed as b% by mass, the content of the compound (1) in the non-aqueous electrolyte solution is 0% by mass relative to 0%. There is no particular limitation as long as it satisfies 0.05≦a/b≦1.50. As a preferable range of the content b of SiOx alone, 0.01≦b≦15 is preferable, and 1≦b≦11 is more preferable. When the content b of SiOx is within the above range, the discharge capacity after the charge/discharge cycle and the discharge rate characteristics are easily compatible without impairing the performance of other batteries. As a method for measuring the SiOx content in the negative electrode active material, quantitative analysis of Si by an inductively coupled plasma emission spectrometry or molybdenum blue absorptiometry of an aqueous solution melted with alkali or diluted hydrofluoric acid, an oxygen-nitrogen-hydrogen analyzer or Quantitative analysis of O by an oxygen-nitrogen analyzer is included. When a carbon material coexists in the negative electrode active material, an analysis by a carbon-sulfur analyzer or an organic element analyzer can be mentioned as the quantification of C atoms.

<2-2. Carbon material>
The negative electrode used in the present invention preferably contains an active material containing a carbon material as a main component (active material containing 50% by mass or more of the carbon material). Specific examples include graphite, amorphous carbon, and carbonaceous materials having a low degree of graphitization. Examples of graphite include natural graphite and artificial graphite. Alternatively, a carbonaceous material such as an amorphous carbon or a graphitized material may be used. Examples of the amorphous carbon include particles obtained by firing bulk mesophase and particles obtained by subjecting a carbon precursor to infusibilization treatment and firing.

Examples of the carbonaceous material particles having a low degree of graphitization include those obtained by firing an organic material at a temperature of usually less than 2500°C. These may be used alone or in any combination of two or more.
The content of the carbon material in the active material is preferably 85.0% by mass or more and 99.9% by mass or less, more preferably 89.0% by mass or more and 99.0% by mass or less, and 94. It is more preferable that the content is 0 mass% or more and 99.0 mass% or less. When the content is within the above range, the discharge capacity after the charge/discharge cycle and the discharge rate characteristics are easily compatible with each other.

<3. Positive electrode>
Examples of the positive electrode material used as the active material of the positive electrode of the non-aqueous secondary battery used in the present invention include, for example, a lithium cobalt composite oxide represented by LiCoO ₂ and a lithium nickel composite oxide represented by LiNiO ₂ , A lithium transition metal composite oxide such as a lithium manganese composite oxide represented by LiMnO _{2 or} LiMn ₂ O ₄ , a transition metal oxide such as manganese dioxide, or a mixture of these composite oxides may be used. Furthermore, TiS ₂ , FeS ₂ , Nb ₃ S
₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , CrO ₃ , V ₃ O ₃ , FeO ₂ , GeO ₂ and L.
i(Ni _1/3 Mn _1/3 Co _1/3 )O ₂ , LiFePO ₄ or the like may be used, and Li(Ni _0.5 Mn _0.3 Co _0.2 )O _2, Li(Ni _0.5 Mn _{0
． 2} Co _0.3 )O _2, Li(Ni _0.6 Mn _0.2 Co _0.2 )O _2, Li(Ni _0.
8 Mn _0.1 Co _0.1 )O _{2 and} Li(Ni _0.8 Co _0.15 Al _0.05 )O ₂ are particularly preferable.

<4. 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 used in the present invention is usually used by impregnating this separator.
There is no particular limitation on the material and shape of the separator, and any known material can be used as long as the effects of the present invention are not significantly impaired. Among these, a resin, glass fiber, inorganic material, etc. formed of a stable material for the non-aqueous electrolyte used in the present invention are used, and a porous sheet or a non-woven fabric-like material excellent in liquid retention is used. Is preferably used.

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

The thickness of the separator is arbitrary, 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 the separator is too thin than the above range, the insulating property and mechanical strength may decrease. On the other hand, if the thickness is more than the above range, not only the battery performance such as rate characteristics may deteriorate, but also the energy density of the entire non-aqueous electrolyte secondary battery may decrease.

Furthermore, when using a porous material such as a porous sheet or a non-woven fabric as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, and 45%.
The above is more preferable, and usually 90% or less, preferably 85% or less, more preferably 75% or less. If the porosity is smaller than the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. On the other hand, if it is larger than the above range, the mechanical strength of the separator tends to decrease, and the insulating property tends to decrease.

The average pore size of the separator is also arbitrary, but is usually 0.5 μm or less and 0.2 μm.
The following is preferable, and it is usually 0.05 μm or more. When the average pore diameter exceeds the above range, short circuit is likely to occur. On the other hand, if it is less than the above range, the film resistance may increase and the rate characteristics may deteriorate.
On the other hand, as the inorganic material, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used. Things are used.

As the form, a non-woven fabric, a woven fabric, or a thin film-shaped one such as a microporous film is used. In the form of a thin film, one 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 above-mentioned independent thin film shape, a separator formed by forming a composite porous layer containing the particles of the inorganic material on the surface layer of the positive electrode and/or the negative electrode using a resin binder can be used. For example, the porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

<5. Conductive material>
The positive electrode and the negative electrode may include a conductive material in order to improve conductivity. Any known conductive material can be used as the conductive material. Specific examples thereof include metal materials such as copper and nickel; 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 be used individually by 1 type and may be used together by 2 or more types in arbitrary combinations and ratios.

The conductive material is usually 0.01 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and usually 50 parts by mass or less, relative to 100 parts by mass of the positive electrode material or the negative electrode material.
It is preferably used in an amount of 30 parts by mass or less, more preferably 15 parts by mass or less.
If the content is less than the above range, the conductivity may be insufficient. If it exceeds the above range, the battery capacity may decrease.

<6. Binder>
The positive electrode and the negative electrode described above may contain a binder in order to improve the binding property. The binder is
The material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used for manufacturing the electrode.
In the case of the coating method, any material can be used as long as it can be dissolved or dispersed in the liquid medium used for manufacturing the electrode, and specific examples include polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, aromatic polyamide, cellulose and nitro. Resin-based polymers such as cellulose; rubber-like polymers such as SBR (styrene/butadiene rubber), NBR (acrylonitrile/butadiene rubber), fluororubber, isoprene rubber, butadiene rubber, ethylene/propylene rubber; styrene/butadiene/styrene blocks Copolymer or hydrogenated product thereof, EPDM (ethylene/propylene/diene terpolymer), styrene/ethylene/
Thermoplastic elastomeric polymers such as butadiene/ethylene copolymer, styrene/isoprene/styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene/vinyl acetate copolymer Soft resinous polymers such as coalesced and propylene/α-olefin copolymers; high fluorine-based polymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene/ethylene copolymers Molecules: Polymer compositions having ion conductivity of alkali metal ions (particularly lithium ions) and the like can be mentioned. These substances may be used alone or in any combination of two or more at any ratio.

The proportion of the binder is usually 0.1 parts by mass or more, preferably 1 part by mass or more, more preferably 3 parts by mass or more, and usually 50 parts by mass with respect to 100 parts by mass of the positive electrode material or the negative electrode material. It is below, preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 8 parts by mass or less. When the proportion of the binder is within the above range, the binding property of the electrode can be sufficiently maintained, the mechanical strength of the electrode can be maintained, and it is preferable in terms of cycle characteristics, battery capacity and conductivity.

<7. Liquid medium>
As the liquid medium for forming the slurry, if it is a solvent capable of dissolving or dispersing the active material, the conductive material, the binder, and the thickener used as necessary, it is particularly suitable for the type. There is no limitation, 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; benzene, toluene, xylene,
Aromatic hydrocarbons such as methylnaphthalene; Heterocyclic compounds such as quinoline and pyridine; Ketones such as acetone, methyl ethyl ketone and cyclohexanone; Esters such as methyl acetate and methyl acrylate; Diethylenetriamine, N,N-dimethylaminopropylamine And the like; ethers such as diethyl ether and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide;
An aprotic polar solvent such as hexamethylphosphamide, dimethylsulfoxide and the like can be mentioned. In addition, these may be used individually by 1 type and may be used together by 2 or more types in arbitrary combinations and ratios.

<8. Thickener>
When an aqueous medium is used as the liquid medium for forming the slurry, it is preferable to make it into a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). Thickeners are commonly used to adjust the viscosity of slurries.
The thickener is not limited unless the effects of the present invention are significantly limited, but specifically, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof. Etc. These may be used alone or in any combination of two or more at any ratio.

When a thickener is further used, it is usually 0.1 part by mass or more, preferably 0.5 part by mass or more, more preferably 0.6 part by mass or more, relative to 100 parts by mass of the positive electrode material or the negative electrode material. Further, it is usually 5 parts by mass or less, preferably 3 parts by mass or less, more preferably 2 parts by mass or less. If it is less than the above range, the coating property may be significantly reduced, and if it exceeds the above range,
The proportion of the active material in the active material layer may decrease, which may cause a problem of decreasing the capacity of the battery and increase the resistance between the active materials.

<9. Current collector>
The material of the 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, tantalum, and copper; carbonaceous materials such as carbon cloth and carbon paper. Among these, metal materials, especially aluminum are preferable.

Examples of the shape of the current collector include a metal foil, a metal column, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foam metal in the case of a metal material, and a carbon plate in the case of a carbonaceous material, Examples thereof include carbon thin films and carbon cylinders. Of these, metal thin films are preferred.
The thin film may be appropriately formed in a mesh shape.
Although the thickness of the current collector is arbitrary, it is usually 1 μm or more, preferably 3 μm or more, and 5 μm.
The above is more preferable, and it is usually 1 mm or less, preferably 100 μm or less, and 50 μm.
It is more preferably m or less. If the thin film is within the above range, the strength required as a current collector is maintained,
It is also preferable from the viewpoint of handleability.

<10. Battery design>
[Electrode group]
The electrode group has a laminated structure including the positive electrode plate and the negative electrode plate with the separator interposed therebetween,
Further, any of the above-mentioned positive electrode plate and negative electrode plate may be spirally wound with the separator interposed therebetween. 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 usually 40% or more, preferably 50% or more, and usually 90% or less, 80% or less. preferable. When the electrode group occupancy rate is below the above range, the battery capacity becomes small. In addition, if it exceeds the above range, the void space is small, the internal pressure rises because the member expands or the vapor pressure of the liquid component of the electrolyte increases due to the high temperature of the battery, and the repeated charge and discharge performance as a battery In some cases, various characteristics such as high temperature storage may be deteriorated, and further, a gas release valve that releases the internal pressure to the outside may operate.

[Current collecting structure]
The current collecting structure is not particularly limited, but in order to more effectively realize the improvement of the discharge characteristics by the non-aqueous electrolyte solution used in the present invention, the structure of reducing the resistance of the wiring part or the bonding part should be adopted. Is preferred. When the internal resistance is reduced in this way, the effect of using the non-aqueous electrolytic solution used in the present invention 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 the terminals is preferably used. Since the internal resistance increases when the area of one electrode increases, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. In the case where the electrode group has the above-mentioned wound structure, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode and bundling them in the terminal.

[Exterior case]
The material of the outer case is not particularly limited as long as it is a substance stable with respect to the non-aqueous electrolyte solution used. Specifically, metal such as nickel-plated steel plate, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminated film of resin and aluminum foil (
A laminated film) is used. From the viewpoint of weight reduction, a metal of aluminum or aluminum alloy, or a laminated film is preferably used.

In the outer case using the metals, laser welding, resistance welding, ultrasonic welding to weld the metals to each other to form a hermetically sealed structure, or a caulking structure using the metals through a resin gasket. There are things to do. Examples of the outer case using the laminate film include those having a sealed structure by heat-sealing resin layers.
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 a resin layer is heat-sealed via a collector terminal to form a hermetically sealed structure, a metal and a resin are bonded, so a resin having a polar group or a modification having a polar group introduced as an intervening resin. Resin is preferably used.

[Protective element]
As the above-mentioned protection element, the PTC (Po which increases resistance when abnormal heat generation or excessive current flows)
Examples include a Situative Temperature Coefficient, a temperature fuse, a thermistor, and a valve (current cutoff valve) that cuts off the current flowing through the circuit due to a sudden increase in internal pressure or internal temperature of the battery during abnormal heat generation. It is preferable to select the protective element under the condition that it does not operate at high current in normal use, and from the viewpoint of high output, it is more preferable to design so as not to cause abnormal heat generation or thermal runaway without the protective element.

[Exterior body]
The non-aqueous electrolyte secondary battery of the present invention is usually constructed by accommodating the above-mentioned non-aqueous electrolyte, negative electrode, positive electrode, separator and the like in an outer casing. There is no limitation on the outer package, and any known package can be used as long as the effects of the present invention are not significantly impaired.
Specifically, the material of the outer package is arbitrary, but, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is usually used.
The shape of the outer package is also arbitrary, and may be, for example, a cylindrical type, a rectangular type, a laminated type, a coin type, a large size, or the like.

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

(Example 1)
[Fabrication of negative electrode]
A mixture of graphite and SiO (x=1 commercial product) was used as the negative electrode active material. Graphite and SiO
Were mixed so that the content of SiO was 5% by mass with respect to the total amount. To 94% by mass of this mixture, 3% by mass of sodium carboxymethyl cellulose was used as a thickener and a binder.
Aqueous dispersion was added so that the amount of carbon black was 3% by mass, and the mixture was slurried by mixing with a disperser. The obtained slurry was applied to a copper foil having a thickness of 20 μm, dried, and rolled with a press to give a diameter of 12
． It was cut into a 5 mm disk shape to obtain the negative electrode of Example 1.

[Counter electrode production]
In a dry argon atmosphere, a lithium metal foil was cut into a disk shape having a diameter of 14 mm to form a counter electrode.

[Preparation of electrolyte]
Under a dry argon atmosphere, ethylene carbonate (EC) and ethyl methyl carbonate (
Dry LiPF ₆ was dissolved in a mixture with EMC (volume ratio 30:70) at a ratio of 1 mol/L to prepare an electrolytic solution, which was used as a basic electrolytic solution. Bis(2,2,2-trifluoroethyl)phosphonate was mixed with this basic electrolytic solution so that the concentration was 3.0% by mass to obtain an electrolytic solution of Example 1.

[Manufacture of coin-type lithium secondary battery]
The negative electrode, the counter electrode, the electrolytic solution, and the separator made of polypropylene are laminated in the order of the negative electrode, the electrolytic solution, the separator, and the counter electrode, and sealed in a coin-shaped metal container to produce a coin-type lithium-ion secondary battery. did.

[Evaluation of discharge capacity and discharge rate characteristics after charge/discharge cycle]
After charging for 16 hours at a current value of 0.05 C (the current value for discharging the rated capacity for 1 hour rate for 1 hour is 1 C. The same applies hereinafter), the lithium counter electrode is charged at a current value of 0.1 C. It was discharged to 1500 mV. Then, charge to 5 mV with a current value of 0.05 C, and
． Discharging to 1500 mV at a current value of 1 C was repeated twice to stabilize the battery.
After that, as charge/discharge cycle measurement, charge/discharge at a low rate was repeated once, charge/discharge at a high rate was repeated 9 times, and a total of 10 charge/discharge cycles was defined as 1 set, which was 4 sets, for a total of 40 cycles. It was charged and discharged. Charge and discharge at a low rate was performed by charging to 5 mV at a current value of 0.05 C and then discharging to 1500 mV at a current value of 0.1 C. Charge and discharge at high rate, current value is 0
． After charging to 5 mV at 5 C, it was discharged to 1500 mV at a current value of 1 C. The discharge capacity at the 40th cycle (mAh/g) was determined as the discharge capacity after the charge/discharge cycle. The discharge capacity was divided by the weight of the active material contained in the electrode to obtain the capacity per unit weight. Also,
As the rate characteristics after the charge/discharge cycle, charge/discharge was performed once at a low rate after 40 cycles of charge/discharge, and [(discharge capacity at 40th cycle)/(discharge capacity at low rate after 40 cycles)]× The rate characteristic (%) was obtained from 100. The respective results are shown in Table 1.

(Example 2)
Using the negative electrode active material mixed so that the content of SiO was 10 mass% with respect to the total amount of graphite and SiO, and the concentration of bis(2,2,2-trifluoroethyl)phosphonate was 1
． A coin type lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that the content was 0% by weight. The results are shown in Table 1.

(Example 3)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 2, bis(2,2
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 2 except that 2,2-trifluoroethyl)methylphosphonate was used. The results are shown in Table 1.

(Example 4)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 1, bis(2,2
A coin type lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Example 5)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 2, bis(2,2
A coin type lithium secondary battery was prepared and evaluated in the same manner as in Example 2 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Example 6)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 1, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 2, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 2. The results are shown in Table 1.

(Comparative Example 1)
The concentration of bis(2,2,2-trifluoroethyl)phosphonate of Example 2 was 0.1% by mass.
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 2 except that the above was adopted. The results are shown in Table 1.

(Comparative example 2)
A coin-type lithium secondary battery was produced in the same manner as in Example 2 except that the concentration of bis(2,2,2-trifluoroethyl)phosphonate in Example 2 was adjusted to 20.0% by mass. And evaluated. The results are shown in Table 1.

(Comparative example 3)
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 2 except that the negative electrode active material was mixed so that the SiO content was 25 mass% with respect to the total amount of graphite and SiO. It was The results are shown in Table 1.

(Comparative example 4)
A coin-type lithium secondary battery was produced in the same manner as in Comparative Example 3 except that the concentration of bis(2,2,2-trifluoroethyl)phosphonate in Comparative Example 3 was 50.0% by mass. And evaluated. The results are shown in Table 1.

(Comparative example 5)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 1, bis(2,2
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 1 except that 2,2-trifluoroethyl)methylphosphonate was used. The results are shown in Table 1.

(Comparative example 6)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 2, bis(2,2
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 2 except that 2,2-trifluoroethyl)methylphosphonate was used. The results are shown in Table 1.

(Comparative Example 7)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 3, bis(2,2
A coin type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 3 except that 2,2-trifluoroethyl)methylphosphonate was used. The results are shown in Table 1.

(Comparative Example 8)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 4, bis(2,2
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 4 except that 2,2-trifluoroethyl)methylphosphonate was used. The results are shown in Table 1.

(Comparative Example 9)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 1, bis(2,2
A coin type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 1 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Comparative Example 10)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 2, bis(2,2
A coin type lithium secondary battery was produced and evaluated in the same manner as in Comparative Example 2 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Comparative Example 11)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 3, bis(2,2
A coin-type lithium secondary battery was produced and evaluated in the same manner as in Comparative Example 3 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Comparative Example 12)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 4, bis(2,2
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 4 except that methyl 2,2-trifluoroethyl)phosphonoacetate was used. The results are shown in Table 1.

(Comparative Example 13)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 1, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 1. The results are shown in Table 1.

(Comparative Example 14)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 2, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 2. The results are shown in Table 1.

(Comparative Example 15)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 3, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 3. The results are shown in Table 1.

(Comparative Example 16)
Instead of bis(2,2,2-trifluoroethyl)phosphonate of Comparative Example 4, [bis(2
, 2,2-Trifluoroethoxy)phosphinyl]ethyl acetate was used, and a coin-type lithium secondary battery was prepared and evaluated in the same manner as in Comparative Example 4. The results are shown in Table 1.

(Comparative Example 17)
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 2 except that dimethyl phenylphosphonate was used instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 2. went. The results are shown in Table 1.

(Comparative Example 18)
A coin type lithium secondary battery was produced and evaluated in the same manner as in Example 2 except that triethyl phosphonoacetate was used instead of bis(2,2,2-trifluoroethyl)phosphonate of Example 2. It was The results are shown in Table 1.

(Comparative Example 19)
A coin-type lithium secondary battery was prepared and evaluated in the same manner as in Example 7 except that Si was used instead of SiO as the negative electrode active material. The results are shown in Table 2.

As is clear from Table 1 above, the batteries manufactured in Examples 1 to 7 are superior to Comparative Examples 1 to 19 in the balance between the discharge capacity after the charge/discharge cycle and the discharge rate characteristics. Examples 1-2 and Comparative Examples 1-4, Example 3 and Comparative Examples 5-8, Examples 4-5 and Comparative Examples 9-1
2. As can be seen from Examples 6 to 7 and Comparative Examples 13 to 16, when the ratio of the content of the compound (1) and SiOx is out of the range corresponding to the present invention, the capacity and/or rate characteristics are lowered. I understand. In addition, from Examples 2, 3, 5, and 7 and Comparative Examples 17 to 18, the compound (1) was P-OCH2CF.
It can be seen that it is necessary to have 3 substructures. Further, it is understood from Example 7 and Comparative Example 19 that the effect is exhibited when the negative electrode active material is SiOx which is a metal oxide.
The cycle test period in each of the examples and comparative examples shown in Table 1 above is modeled as a relatively short period, but a significant difference is confirmed. Since the actual use of non-aqueous electrolyte secondary batteries may last for several years, the difference between these results is that if long-term use is assumed,
It can be understood that the difference becomes even more remarkable.

The non-aqueous electrolyte secondary battery of the present invention is excellent in the balance between the discharge capacity after the charge/discharge cycle and the discharge rate characteristics. Therefore, the non-aqueous secondary battery of the present invention can be used for various known applications. Specific examples include, for example, laptop computers, pen input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copiers, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini disks. , Walkie-talkie, electronic organizer, calculator, memory card, portable tape recorder, radio, backup power supply, motor, automobile, motorcycle, motorbike, bicycle, lighting equipment, toys, game equipment, clock, electric tool, strobe, camera, home Backup power supply, office backup power supply, load leveling power supply, natural energy storage power supply, lithium ion capacitor, etc.

Claims (6)

A non-aqueous electrolytic secondary battery comprising a non-aqueous electrolytic solution, a negative electrode and a positive electrode, wherein the negative electrode contains Si, wherein the non-aqueous electrolytic solution is a non-aqueous solvent and a compound (1) represented by the following formula (1): The negative electrode contains an active material represented by SiOx (0.5≦x≦1.6), and the content of the compound (1) is a mass% based on the whole non-aqueous electrolyte solution. A non-aqueous electrolytic secondary battery satisfying 0.05≦a/b≦1.50 when the SiOx content relative to the entire active material is b mass %.

(In the above formula (1), R ¹ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, or an alkyl group having 6 to 10 carbon atoms which may have a halogen atom. Represents an aryl group, and R ² represents a hydrogen atom, a halogen atom, or a carbon atom which may have a halogen atom.
5 represents an alkyl group having 5 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms which may have a halogen atom, or a group represented by the following formula (2), n is 0 or 1, and p is 0 or 1. is there. )

(In the formula (2), R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a halogen atom, and q is 1 to 5.) The non-aqueous electrolyte solution according to claim 1, wherein R ¹ in the formula (1) is a trifluoroethyl group and p is 1. As the compound (1), bis(2,2,2-trifluoroethyl)phosphonate, bis(2
,2,2-Trifluoroethyl)methylphosphonate, methyl bis(2,2,2-trifluoroethyl)phosphonoacetate and ethyl [bis(2,2,2-trifluoroethoxy)phosphinyl]ethyl acetate The non-aqueous electrolyte solution according to claim 1 or 2, containing at least one selected. The nonaqueous electrolytic solution according to claim 1, wherein the content of the compound (1) is 0.01% by mass or more and 10% by mass or less. The nonaqueous electrolytic solution according to claim 1, wherein the content of SiOx in the negative electrode active material is 0.01% by mass or more and 15% by mass or less. The said negative electrode contains the active material which has a carbon material as a main component, and the content is 85.0 mass% or more and 99.9 mass% or less with respect to the said whole negative electrode active material. Non-aqueous electrolyte solution.