KR20190058708A - Nonaqueous electrolyte solution and nonaqueous electrolyte secondary battery - Google Patents

Abstract

In particular, it is an object of the present invention to provide a non-aqueous liquid electrolyte secondary battery which is excellent in the amount of low gas generation and high-temperature cycle durability in a battery having a high positive electrode potential. A non-aqueous liquid electrolyte secondary battery comprising a nonaqueous electrolyte solution containing a lithium salt and a nonaqueous solvent dissolving the lithium salt, a negative electrode capable of lithium ion intercalation and deintercalation, and a positive electrode, And a fluorinated cyclic carbonate represented by the general formula (3), wherein the cyclic carbonate represented by the general formula (1) is contained in the non-aqueous solvent in an amount of not more than 15% by volume the non-aqueous liquid electrolyte secondary cell characterized in that which is much contained, even when the upper limit of the operation voltage of the positive electrode 4.5 V or more to the Li / Li ⁺ reference, that generated gas amount, a high temperature cycle durability is excellent non-aqueous liquid electrolyte secondary battery has do.

Description

TECHNICAL FIELD [0001] The present invention relates to a non-aqueous liquid electrolyte and a non-aqueous liquid electrolyte secondary battery,

The present invention relates to a non-aqueous liquid electrolyte and a secondary battery comprising the non-aqueous liquid electrolyte. More specifically, the present invention relates to a secondary battery comprising a specific cyclic carbonate, a fluorinated cyclic carbonate, and a fluorinated chain carbonate, Type carbonate is contained in an amount of more than 20% by volume.

A nonaqueous electrolyte solution containing a specific cyclic carbonate, a fluorinated cyclic carbonate, and a fluorinated chain carbonate and containing a cyclic carbonate in an amount of more than 15% by volume in a nonaqueous solvent, And the upper limit operating potential of the non-aqueous liquid electrolyte secondary battery is 4.5 V or more based on Li / Li ⁺ .

A nonaqueous electrolyte secondary battery such as a lithium secondary battery has been put to practical use as a wide power source ranging from a power source for a portable electronic device such as a mobile phone and a notebook PC to a power source for a driving vehicle such as an automobile or a large power source for a station. However, with the recent improvement in the performance of electronic apparatuses, application to a driving vehicle power source and a large power source for stationary use, there is a growing demand for a secondary battery to be applied. As a result, high performance of the battery characteristics of the secondary battery, It is required to achieve a high level of improvement in storage characteristics, cycle characteristics, and the like.

Particularly, high performance and versatility of portable devices and the like are increasingly progressing, and it is strongly desired to further increase the energy density of the lithium secondary battery as a power source thereof. In addition, there is a demand for a battery having excellent performance balance with respect to safety, cost competitiveness, and service life (especially at high temperature), and a lithium secondary battery capable of meeting these demands has been actively developed.

In such a situation, various proposals have been made to improve the energy density as a lithium secondary battery. There are several ways to improve the energy density of the battery, but one of them is to raise the operating voltage as a battery. Particularly, for a device operating at a high voltage, the use of a high voltage battery having a high operating voltage is a particularly effective means, and the demand for such a battery is expected to become higher in the future.

Non-aqueous liquid electrolyte The non-aqueous liquid electrolyte used in the secondary battery is usually composed mainly of an electrolyte and a non-aqueous solvent. Examples of the main component of the nonaqueous solvent include: cyclic carbonates such as ethylene carbonate and propylene carbonate; Chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic carboxylic acid esters such as? -butyrolactone,? -valerolactone, and the like are used.

Various non-aqueous solvents, electrolytes, and auxiliary agents have also been proposed to improve battery properties such as load characteristics, cycle characteristics, storage characteristics, and low-temperature characteristics of batteries using these non-aqueous liquid electrolytes. For example, by using vinylene carbonate and a derivative thereof or a vinylethylene carbonate derivative, a cyclic carbonate having a double bond reacts preferentially with the negative electrode (negative electrode) to form a good film on the surface of the negative electrode, It is disclosed in Patent Documents 1 and 2 that the storage characteristics and the cycle characteristics are improved.

However, with respect to a demand for a high capacity, high-voltage battery which is increased, a battery using a conventional non-aqueous liquid electrolyte can not satisfactorily obtain the required battery performance. In recent years, as a development policy of a non-aqueous liquid electrolyte capable of stably operating in a high voltage battery system, a method of improving oxidation resistance by fluorinating a conventional non-aqueous solvent has been studied.

For example, Patent Document 3 discloses a graphite negative electrode 5.0 V class battery using a nonaqueous electrolytic solution obtained by mixing 4,5-difluoroethylene carbonate fluorinated with a cyclic carbonate and ethylene carbonate, The suppression effect of gas generation is confirmed. However, as to the battery characteristics, improvement in the initial capacity and initial load characteristics is only confirmed, and the characteristics of the durability battery are still unclear.

In addition, the electrolytic solution composed solely of such a high-viscosity solvent is not only deteriorated in battery characteristics at low temperature in a nonaqueous electrolyte solution, but is difficult to handle during pouring, and the wettability of the separator is very low Loses.

Patent Documents 4 and 5 disclose a technique for improving the battery characteristics such as cycle characteristics in a 4.2 to 4.3 V battery based on a graphite negative electrode, that is, a battery having a positive electrode potential of approximately 4.35 V. Examples of the electrolyte include ethylene carbonate, 4-fluoroethylene Carbonate, and fluorinated chain type carbonate is described. However, in the present technology, it is essential to contain a carboxylic acid ester or a non-fluorinated chain type carbonate for the purpose of improving the rate characteristics of the battery and lowering the viscosity of the electrolytic solution, and it is essential that the positive electrode potential is 4.35 V In the above-mentioned region, oxidative decomposition of these is concerned. The patent literature does not disclose means for solving these problems.

Patent Document 6 discloses a non-aqueous liquid electrolyte obtained by mixing ethylene carbonate, 4-fluoroethylene carbonate and fluorinated chain carbonate for the purpose of suppressing generation of gas with less cycle deterioration. However, this patent In the literature, as well as the above-mentioned known documents, only the technology relating to a battery using a low potential region of a specific LiCoO ₂ positive electrode is disclosed in the examples. The patent document does not disclose a technique for solving the high temperature preservation under high voltage at which the upper limit operating potential of the positive electrode exceeds 4.35 V, and the deterioration of the durability in the cycle.

Patent Document 7 discloses a capacity deterioration suppressing technique using a mixed solvent of a cyclic carbonate, a fluorinated cyclic carbonate and a fluorinated chain carbonate for a 4.3 V battery using a silicon negative electrode. However, in the graphite anode exemplified as a negative electrode other than the silicon system, only remarkable capacity deterioration due to the reduction decomposition of the fluorinated cyclic carbonate occurs, and the patent document discloses only the characteristic of the deterioration suppression technique for the silicon negative electrode . In addition, the patent literature does not mention or suggest a high voltage battery exceeding 4.3V.

Patent Document 8 discloses a technique for reducing the charge-discharge cycle characteristics at a high temperature and the swelling due to a high temperature preservation gas using a mixed solvent of a cyclic carbonate, a fluorinated cyclic carbonate and a fluorinated chain carbonate as a battery of 4.35 V or more . However, what is actually being confirmed is the result at 4.4 V, and the characteristics in the higher voltage range are not known.

Japanese Patent Application Laid-Open No. 8-45545 Japanese Patent Application Laid-Open No. 4-87156 Japanese Patent Application Laid-Open No. 2003-168480 International Publication No. 2010/004952 International Publication No. 2010/013739 International Publication No. 2007/043526 Japanese Patent Application Laid-Open No. 2007-294433 Japanese Patent Application Laid-Open No. 2007-250415

The present invention solves the above-mentioned problems that are caused when a performance required for a recent secondary battery is to be achieved, and in particular, it is an object of the present invention to provide a battery having a high positive operation potential of a positive electrode, And an object of the present invention is to provide an excellent non-aqueous liquid electrolyte secondary battery.

The inventors, as a result of extensive study example in order to solve the above problems, Non-by using a specific solvent as the non-aqueous liquid electrolyte to be used in aqueous liquid electrolyte secondary battery, the upper limit potential of the positive electrode Li / Li ⁺ reference to above 4.5 V high-voltage design cell The present inventors have found that a non-aqueous liquid electrolyte secondary battery excellent in durability characteristics such as a low generation gas amount and a high temperature cycle can be realized.

That is, the gist of the present invention is as follows.

a) Lithium salt and to it contains a non-aqueous solvent for dissolving the non-aqueous liquid electrolyte, the lithium ion comprising storing and release the negative electrode, and as a non-aqueous liquid electrolyte secondary battery comprising a positive electrode, the upper limit of the operation voltage of the positive electrode Li / Li ⁺ And the non-aqueous liquid electrolyte contains a cyclic carbonate represented by the following formula (1), a fluorinated cyclic carbonate represented by the following formula (2), and a fluorinated chain carbonate represented by the following formula (3) And the non-aqueous solvent contains more than 15% by volume of the cyclic carbonate represented by the general formula (1).

[Chemical Formula 1]

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)

(2)

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different)

(3)

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do)

b) The non-aqueous liquid electrolyte secondary battery according to a), wherein the total amount of the carbonate represented by the general formulas (1) to (3) in the non-aqueous liquid electrolyte is 50% by volume or more of the non-aqueous solvent.

c) The non-aqueous liquid electrolyte secondary battery according to a) or b), wherein in the non-aqueous liquid electrolyte, the fluorinated chain carbonate represented by the general formula (3) is contained in the non-aqueous solvent in an amount of 5% by volume or more.

The nonaqueous electrolyte secondary particle according to any one of the items a) to c), characterized in that the total amount of the carbonate represented by the general formulas (1) and (2) in the nonaqueous electrolyte is 25% battery.

The nonaqueous electrolyte secondary battery according to any one of the above a) to e), wherein in the nonaqueous electrolyte solution, the cyclic carbonate represented by the general formula (1) is contained in the nonaqueous solvent in an amount of 20% .

f) The non-aqueous liquid electrolyte secondary battery according to any one of a) to e), wherein the cyclic carbonate represented by the general formula (1) is at least one selected from ethylene carbonate and propylene carbonate.

g) The fluorinated cyclic carbonate represented by the general formula (2) is at least one selected from the group consisting of 4-fluoroethylene carbonate and 4,5-difluoroethylene carbonate. A non-aqueous liquid electrolyte secondary battery as claimed.

h) The non-aqueous liquid electrolyte secondary battery according to any one of a) to g), characterized in that the fluorinated chain type carbonate represented by the above general formula (3) contains trifluoroethyl methyl carbonate.

(i) any one of a) to h) characterized in that the positive electrode contains a positive electrode active material containing at least one selected from the group consisting of lithium transition metal compounds represented by the following general formulas (4) to (6) Based secondary battery according to claim 1.

Li [Li _a M _x Mn _{2- x a} ] O _{4 +} (4)

(Wherein 0? A? 0.3, 0.4 <x <1.1 and -0.5 <delta <0.5, and M is at least one of transition metals selected from Ni, Cr, Fe, )

Li _x M1 _y M2 _z O _2-delta ... (5)

(In the formula (5), 1? X? 1.3, 0? Y? 1, 0? Z? 0.3 and -0.1?? 0.1, M1 represents Ni, Co and / or Mn, M2 represents Fe , At least one element selected from Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, Ta, Be, Al, Ca, Sc and Zr )

αLi ₂ MO ₃ (1-α) LiM'O ₂ ... (6)

(Wherein, in the formula (6), 0 < alpha < 1, M represents at least one of the metal elements having an average oxidation number of +4, and M 'represents at least one metal element having an average oxidation number of +3)

j) The non-aqueous liquid electrolyte secondary battery according to any one of a) to i), wherein the negative electrode contains a negative electrode active material composed of graphite particles.

k) a nonaqueous electrolyte solution containing a lithium salt and a nonaqueous solvent dissolving the lithium salt, a negative electrode capable of intercalating and deintercalating lithium ions, and a positive electrode, wherein the nonaqueous electrolytic solution is represented by the following general formula (1) , A fluorinated cyclic carbonate represented by the following general formula (2), and a fluorinated chain-like carbonate represented by the following general formula (3), and a cyclic carbonate represented by the general formula (1) And a positive electrode active material containing at least one selected from the group consisting of lithium transition metal compounds represented by the following general formulas (4) to (6), wherein the positive electrode contains more than 15% by volume of carbonate A non-aqueous liquid electrolyte secondary battery.

[Chemical Formula 4]

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)

[Chemical Formula 5]

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different)

[Chemical Formula 6]

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do)

Li [Li _a M _x Mn _{2- x a} ] O _{4 +} (4)

(Wherein 0? A? 0.3, 0.4 <x <1.1 and -0.5 <delta <0.5, and M is at least one of transition metals selected from Ni, Cr, Fe, )

Li _x M1 _y M2 _z O _2-delta ... (5)

(In the formula (5), 1? X? 1.3, 0? Y? 1, 0? Z? 0.3 and -0.1?? 0.1, M1 represents Ni, Co and / or Mn, M2 represents Fe , At least one element selected from Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, Ta, Be, Al, Ca, Sc and Zr )

αLi ₂ MO ₃ (1-α) LiM'O ₂ ... (6)

(Wherein, in the formula (6), 0 < alpha < 1, M represents at least one of the metal elements having an average oxidation number of +4, and M 'represents at least one metal element having an average oxidation number of +3)

1. A nonaqueous electrolyte solution comprising a lithium salt and a nonaqueous solvent dissolving the lithium salt, wherein the nonaqueous electrolytic solution contains a cyclic carbonate represented by the following general formula (1), a fluorinated cyclic carbonate represented by the following general formula (2) And a fluorinated chain-like carbonate represented by the following general formula (3), and further contains a cyclic carbonate represented by the general formula (1) in a non-aqueous solvent in an amount of more than 20% by volume.

(7)

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)

[Chemical Formula 8]

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different)

[Chemical Formula 9]

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do)

m) as used for the lithium salt and to it contains a non-aqueous solvent for dissolving the non-aqueous liquid electrolyte secondary battery of the non-aqueous liquid electrolyte comprising the non-aqueous liquid electrolyte secondary battery, the upper limit of the operation voltage of the positive electrode of 4.5 to Li / Li ⁺ reference V, wherein the non-aqueous liquid electrolyte comprises a cyclic carbonate represented by the following formula (1), a fluorinated cyclic carbonate represented by the following formula (2), and a fluorinated chain represented by the following formula (3) Type nonaqueous electrolyte secondary battery according to claim 1, wherein the nonaqueous solvent contains a cyclic carbonate represented by the general formula (1) in an amount of more than 15% by volume.

[Chemical formula 10]

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)

(11)

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different)

[Chemical Formula 12]

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do.)

In a battery design with a high operating voltage, a method for improving battery durability such as storage characteristics and cycle characteristics has been generally proposed by using a fluorine-modified non-aqueous electrolyte solution which is considered to have high oxidation resistance.

On the other hand, it has been generally considered that the cyclic carbonate solvent represented by the general formula (1) is not suitable for a high voltmeter because of its low resistance to the positive oxidation reaction. In the present invention, And the cyclic carbonate is introduced into the non-aqueous liquid electrolyte. That is, the present inventors have found that a nonaqueous electrolytic solution obtained by mixing a cyclic carbonate represented by the general formula (1) and a fluorinated cyclic carbonate and a fluorinated chain-like carbonate, The battery durability is remarkably improved as compared with a non-aqueous liquid electrolyte made of a solvent, and the inventors have found that the above problems can be solved, thereby completing the present invention.

According to the present invention, it is possible to provide a lithium secondary battery designed especially for a high-voltage specification, which is excellent in durability characteristics such as cycle and preservation of a battery at high temperature and has excellent battery characteristics at low temperature. An aqueous electrolyte secondary battery can be provided.

 Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited thereto, and can be carried out by arbitrary modification.

As the non-aqueous liquid electrolyte secondary battery of the present invention, a lithium secondary battery is particularly preferable. The non-aqueous liquid electrolyte secondary battery of the present invention can have a known structure and typically includes a negative electrode and a positive electrode capable of absorbing and desorbing ions (for example, lithium ion), a non-aqueous liquid electrolyte, and a separator.

1. Non-aqueous liquid electrolyte

1-1. Non-aqueous solvent

1-1-1. menstruum

The non-aqueous liquid electrolyte according to the present invention comprises a fluorinated cyclic carbonate containing a cyclic carbonate represented by the following formula (1) and represented by the following formula (2), and a fluorinated chain type represented by the following formula (3) And a carbonate. In addition, as the non-aqueous solvent, it is possible to use non-fluorinated chain type carbonate, cyclic and chain type carboxylic acid ester, ether compound, sulfone type compound and the like.

<Ring-shaped carbonate represented by the general formula (1)>

[Chemical Formula 13]

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)

R ₁ is hydrogen or a hydrocarbon group which may have a substituent, and examples of the hydrocarbon group which may have a substituent include an alkyl group having 1 to 4 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The cyclic carbonate represented by the general formula (1) (hereinafter, also referred to as a non-fluorinated cyclic carbonate) includes those having an alkylene group having 2 to 4 carbon atoms.

Specific examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate, and butylene carbonate. Of these, ethylene carbonate and propylene carbonate are particularly preferable in terms of improvement in battery characteristics derived from improvement in lithium ion dissociation degree and improvement in battery durability.

The cyclic carbonate represented by the general formula (1) may be used singly or two or more kinds may be combined in any combination and ratio.

The amount of the cyclic carbonate represented by the general formula (1) is not particularly limited as long as it is more than 15% by volume in 100% by volume of the nonaqueous solvent. Any amount may be used as long as it does not significantly impair the effect of the present invention. Is preferably at least 20% by volume, more preferably at least 25% by volume, and most preferably at least 30% by volume, based on 100% by volume of the non-aqueous solvent. By setting this range, it is easy to avoid a decrease in the electric conductivity derived from the decrease of the dielectric constant of the non-aqueous liquid electrolyte and to set the high current discharge characteristic, the stability to the negative electrode, and the cycle characteristics of the non-aqueous liquid electrolyte secondary battery within a preferable range. The upper limit is preferably 70 vol% or less, more preferably 65 vol% or less, and most preferably 60 vol% or less. By setting this range, the viscosity of the non-aqueous liquid electrolyte can be set in an appropriate range to suppress the lowering of the ionic conductivity, and the load characteristic and the durability of the non-aqueous liquid electrolyte secondary battery can be easily set within a preferable range.

<Fluorinated cyclic carbonate represented by general formula (2)> [

[Chemical Formula 14]

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different)

R ₂ is hydrogen, fluorine, or a hydrocarbon group which may have a substituent. Examples of the hydrocarbon group which may have a substituent include an alkyl group having 1 to 4 carbon atoms, a monofluoroalkyl group having 1 to 4 carbon atoms, a difluoro And a trifluoroalkyl group having 1 to 4 carbon atoms, preferably an alkyl group having 1 to 2 carbon atoms, a monofluoroalkyl group having 1 to 2 carbon atoms, a difluoroalkyl group having 1 to 2 carbon atoms, and a fluoroalkyl group having 1 to 2 carbon atoms Of a trifluoroalkyl group. Specific examples include methyl, monofluoromethyl, difluoromethyl, trifluoromethyl, ethyl, monofluoroethyl, difluoroethyl and trifluoroethyl groups.

Examples of the fluorinated cyclic carbonate represented by the general formula (2) include cyclic carbonate derivatives having an alkylene group having 2 to 6 carbon atoms.

Specific fluorinated cyclic carbonates include, for example, ethylene carbonate or a fluoride of ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms).

The number of fluorine atoms contained in the fluorinated cyclic carbonate is not particularly limited as long as it is 1 or more, but it is preferable that the fluorinated cyclic carbonate has 1 to 8 fluorine atoms.

Specific examples thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5- 4-fluoro-5-methylethylenecarbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (fluoromethyl) Fluoroethylene carbonate, 4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate , 4,4-difluoro-5,5-dimethylethylene carbonate, and the like.

Among them, it is preferably selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate and 4,5-difluoro-4,5-dimethylethylene carbonate At least one type is more preferable in terms of imparting high ionic conductivity and further preferably forming an interface protective film, and furthermore, at least one kind selected from monofluoroethylene carbonate and 4,5-difluoroethylene carbonate is preferable , In particular, fluoroethylene carbonate is preferable because it makes it easy to keep the storage characteristics and cycle characteristics of the nonaqueous electrolyte secondary battery within a preferable range.

The fluorinated cyclic carbonate represented by the general formula (2) may be used singly or two or more kinds may be used in any combination and proportion.

The amount of the fluorinated cyclic carbonate is not particularly limited and may be any value as long as it does not significantly impair the effect of the present invention. However, it is preferably 1% by volume or more, more preferably 2% by volume or more , Most preferably not less than 4% by volume, preferably not more than 40% by volume, more preferably not more than 30% by volume, and most preferably not more than 15% by volume. Within this range, the non-aqueous liquid electrolyte secondary battery tends to exhibit a sufficient cycle property improving effect, and the discharge capacity retention rate is likely to be lowered due to a decrease in the high temperature storage characteristics and an increase in the gas generation amount.

The total amount (blend amount) of the cyclic carbonate represented by the general formula (1) and the fluorinated cyclic carbonate represented by the general formula (2) is preferably more than 15% by volume, more preferably 15% , More preferably not less than 98 vol%, more preferably not more than 95 vol%, still more preferably not more than 90 vol%. Within this range, the non-aqueous liquid electrolyte secondary battery tends to exhibit a sufficient cycle characteristic improving effect, and it is easy to avoid a decrease in the high-temperature storage characteristics and a decrease in the discharge capacity retention rate due to an increase in the gas generation amount. The amount of the cyclic carbonate represented by the general formula (1) in 100% by volume of the cyclic carbonate solvent composed of the cyclic carbonate represented by the general formula (1) and the fluorinated cyclic carbonate represented by the general formula (2) Is at least 50%, more preferably at least 55%, and even more preferably at least 60%. By designating the amount of the non-fluorinated cyclic carbonate in this manner, the amount of gas generation is suppressed, and the cyclic property improving effect tends to be more easily exhibited.

Further, the fluorinated cyclic carbonate represented by the general formula (2) exhibits not only the solvent but also an effective function as an auxiliary agent described in the following 1-3. When the fluorinated cyclic carbonate represented by the general formula (2) is used as a solvent or an auxiliary, there is no clear boundary, and the compounding amount described in the preceding paragraph can be directly followed.

<Fluorinated Chain Type Carbonate Represented by General Formula (3)> [

[Chemical Formula 15]

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do)

R ₃ may have a substituent and is a hydrocarbon group containing at least one fluorine. Examples of such a hydrocarbon group include a monofluoroalkyl group having 1 to 4 carbon atoms, a difluoroalkyl group having 1 to 4 carbon atoms, Preferably a monofluoroalkyl group having 1 to 2 carbon atoms, a difluoroalkyl group having 1 to 2 carbon atoms, and a trifluoroalkyl group having 1 to 2 carbon atoms. Specific examples thereof include a monofluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a monofluoroethyl group, a difluoroethyl group, and a trifluoroethyl group.

R ₄ is a hydrocarbon group which may have a substituent, and examples of the hydrocarbon group which may have a substituent include an alkyl group having 1 to 4 carbon atoms, a monofluoroalkyl group having 1 to 4 carbon atoms, a difluoroalkyl group having 1 to 4 carbon atoms, A trifluoroalkyl group having 1 to 4 carbon atoms is preferably substituted with an alkyl group having 1 to 2 carbon atoms, a monofluoroalkyl group having 1 to 2 carbon atoms, a difluoroalkyl group having 1 to 2 carbon atoms, and a trifluoroalkyl group having 1 to 2 carbon atoms . Specific examples include methyl, monofluoromethyl, difluoromethyl, trifluoromethyl, ethyl, monofluoroethyl, difluoroethyl and trifluoroethyl groups.

The fluorinated chain type carbonate represented by the general formula (3) preferably has 3 to 7 carbon atoms. The number of fluorine atoms 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 may be bonded to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethylmethyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

Examples of the fluorinated dimethylcarbonate derivative include fluoromethylmethyl carbonate, difluoromethylmethyl carbonate, trifluoromethylmethyl carbonate, bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis ) Carbonate and the like.

Examples of the fluorinated ethylmethylcarbonate derivative include (2-fluoroethyl) methyl carbonate, ethyl fluoromethyl carbonate, (2,2-difluoroethyl) methyl carbonate, (2-fluoroethyl) fluoromethyl carbonate, ethyl (2,2,2-trifluoroethyl) methyl carbonate, (2,2-difluoroethyl) fluoromethyl carbonate, (2-fluoroethyl) difluoromethyl carbonate, ethyl Trifluoromethyl carbonate, and the like.

Examples of the fluorinated diethylcarbonate derivative include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2- fluoroethyl) carbonate, 2-trifluoroethyl) carbonate, 2,2-difluoroethyl-2'-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2- 2'-fluoroethyl carbonate, 2,2,2-trifluoroethyl-2 ', 2'-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate and the like .

The fluorinated chain type carbonate represented by the general formula (3) may be used singly or two or more kinds may be used in any combination and in any ratio.

The amount of the fluorinated chain type carbonate represented by the general formula (3) is preferably not less than 1% by volume, more preferably not less than 5% by volume, further preferably not less than 10% by volume, more preferably not less than 10% by volume, Most preferably at least 15% by volume. By containing the fluorinated chain type carbonate in such a lower limit range, the viscosity of the non-aqueous liquid electrolyte can be controlled within an appropriate range, thereby facilitating handling during pouring, suppressing deterioration of ionic conductivity, Current discharge characteristic and the battery characteristics at low temperature to a preferable range. The fluorinated chain type carbonate represented by the general formula (3) is preferably 90% by volume or less, more preferably 80% by volume or less, and most preferably 75% by volume or less in 100% by volume of the nonaqueous solvent Do. By setting the upper limit in this manner, it is possible to avoid a decrease in the electric conductivity resulting from the reduction of the dielectric constant of the non-aqueous liquid electrolyte and to make the high current discharge characteristic of the non-aqueous liquid electrolyte secondary battery and the battery characteristic at low temperature to be within a preferable range.

The total amount (blend amount) of the cyclic carbonate represented by the general formula (1) and the fluorinated chain type carbonate represented by the general formula (3) is preferably more than 15% by volume, more preferably 15% , Preferably not less than 97 vol%, more preferably not more than 95 vol%. Within this range, the non-aqueous liquid electrolyte secondary battery tends to exhibit a sufficient cycle characteristic improving effect, and it is easy to avoid a decrease in the high-temperature storage characteristics and a decrease in the discharge capacity retention rate due to an increase in the gas generation amount.

The total amount (blend amount) of the cyclic carbonate represented by the general formula (1), the fluorinated cyclic carbonate represented by the general formula (2), and the fluorinated chain carbonate represented by the general formula (3) , Preferably 50 vol% or more, preferably 70 vol% or more, more preferably 75 vol% or more, and most preferably 85 vol% or more. This range not only provides excellent durability of the battery but also allows the viscosity of the non-aqueous liquid electrolyte to fall within an appropriate range to suppress deterioration of the ionic conductivity and further improve the high current discharge characteristics of the non-aqueous liquid electrolyte secondary battery and the battery characteristics at low temperatures So that it becomes easy to achieve a good range. The upper limit is not particularly set and may be 100 volume%.

1-1-2. Other solvents

In addition to the cyclic carbonate represented by the general formula (1), the fluorinated cyclic carbonate represented by the general formula (2), and the fluorinated chain-like carbonate represented by the general formula (3) A solvent may be mixed and used. These solvents include nonfluorinated chain-like carbonates, cyclic carboxylic acid esters, chain-type carboxylic acid esters, ether-based compounds, and sulfone-based compounds.

<Non-Fluorinated Chain Type Carbonate>

As the non-fluorinated chain type carbonate, those having 3 to 7 carbon atoms are preferable. Specific examples include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-i-propyl carbonate, n-propyl-i-propyl carbonate, ethylmethyl carbonate, methyl n-propyl carbonate, , i-butyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, i-butyl ethyl carbonate and t-butyl ethyl carbonate.

Among these, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-i-propyl carbonate, n-propyl-i-propyl carbonate, ethylmethyl carbonate and methyl n-propyl carbonate are preferable, Is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate.

The blending amount of the non-fluorinated chain type carbonate is usually not less than 0.1% by volume, preferably not less than 0.3% by volume, more preferably not less than 0.5% by volume, based on 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the electric conductivity of the non-aqueous liquid electrolyte can be improved, and the large current discharge characteristic of the non-aqueous liquid electrolyte secondary battery can be easily improved. The blending amount of the non-fluorinated chain type carbonate is preferably not more than 40% by volume, more preferably not more than 35% by volume. By setting the upper limit in this manner, the viscosity of the non-aqueous liquid electrolyte can be set in an appropriate range to avoid a decrease in the electric conductivity and to suppress the increase in negative electrode resistance and to make the large current discharge characteristic of the non-aqueous liquid electrolyte secondary battery within a preferable range .

<Ring-shaped carboxylic acid ester>

The cyclic carboxylic acid ester includes, for example, those having 3 to 12 carbon atoms in total in the structural formula.

Specific examples thereof include gamma butyrolactone, gamma valerolactone, gamma caprolactone, and epsilon caprolactone. Among them, gamma-butyrolactone is particularly preferable in terms of improvement in battery characteristics derived from improvement in lithium ion dissociation degree.

The amount of the cyclic carboxylic acid ester to be blended is usually not less than 0.3% by volume, preferably not less than 0.5% by volume, more preferably not less than 1% by volume, based on 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the electric conductivity of the non-aqueous liquid electrolyte can be improved, and the large current discharge characteristic of the non-aqueous liquid electrolyte secondary battery can be easily improved. The amount of the cyclic carboxylic acid ester is preferably 15% by volume or less, more preferably 10% by volume or less, and still more preferably 5% by volume or less. By setting the upper limit in this manner, the viscosity of the non-aqueous liquid electrolyte can be set in an appropriate range to avoid a decrease in the electric conductivity and to suppress the increase in negative electrode resistance and to make the large current discharge characteristic of the non-aqueous liquid electrolyte secondary battery within a preferable range .

<Chain Type Carboxylic Acid Ester>

As the chain type carboxylic acid ester, the total carbon number in the structural formula is 3 to 7.

Specific examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, N-propyl isobutyrate, methyl isobutyrate, ethyl isobutyrate, isopropyl butyrate, isopropyl butyrate, isopropyl butyrate, isopropyl butyrate, isopropyl butyrate, isopropyl butyrate, isopropyl butyrate, Isopropyl butyrate, and the like.

Among them, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, In view of the improvement of the reliability.

The amount of the chain carboxylic acid ester to be blended is usually not less than 0.3% by volume, preferably not less than 0.5% by volume, more preferably not less than 1% by volume, based on 100% by volume of the nonaqueous solvent. By setting the lower limit in this way, the electric conductivity of the non-aqueous liquid electrolyte can be improved, and the large current discharge characteristic of the non-aqueous liquid electrolyte secondary battery can be easily improved. The amount of the chain carboxylic acid ester to be blended is preferably 15 vol% or less, more preferably 10 vol% or less, further preferably 5 vol% or less, in 100 vol% of the non-aqueous solvent. By setting the upper limit in this way, it is easy to suppress the increase of the negative electrode resistance and to set the high current discharge characteristic and the cycle characteristic of the non-aqueous liquid electrolyte secondary battery to a preferable range.

<Ether compound>

As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms, in which a part of hydrogen may be substituted with fluorine, is preferable.

Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, bis (2-fluoroethyl) ether, bis (2,2-difluoroethyl) ether, bis (2,2,2-trifluoroethyl Ethyl ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoro Ethyl) (2,2,2-trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (1,1,2,2-tetrafluoro N-propyl ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-pentafluoro-n-propyl) ether, ethyl (2,2,3,3-tetrafluoro-n-propyl) (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) , (2-fluoro (2,2,3,3-pentafluoro-n-propyl) ether, (2-fluoroethyl) , 2,2-trifluoroethyl n-propyl ether, (3-fluoro-n-propyl) (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,2-trifluoroethyl) ether, 2,2,3,3,3-pentafluoro-n-propyl) (2,2,2-trifluoroethyl) ether, n-propyl (1,1,2,2-tetrafluoroethyl) ether , (3-fluoro-n-propyl) (1,1,2,2-tetrafluoroethyl) ether, (1,1,2,2-tetrafluoroethyl) (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3- (3-fluoro-n-propyl) (n-propyl) ether, 1,1,2,2-tetrafluoroethyl) ether, di- (n- ) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3,3-tetrafluoro-n-propyl) , 3-pentafluoro-n-propyl) (n-propyl) ether, bis (3-fluoro- Propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n- (2,3,3,3-trifluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n (3,3,3-trifluoro-n-propyl) ether, (2,2,3,3,3-pentafluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxy methane, ethoxy Methoxymethane, (2-Fluor Methoxy (2,2,2-trifluoroethoxy) methane, methoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxy methane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2,2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) Fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoro Ethoxy) methane, bis (2,2,2-trifluoroethoxy) methane, (1,1,2,2-tetrafluoroethoxy) (2,2,2-trifluoroethoxy) methane , Bis (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, ethoxymethoxyethane, (2-fluoroethoxy) methoxyethane, methoxy (2,2,2- Methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-tetrafluoroethoxy) 2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, bis (2-fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) , (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, bis (2,2,2-trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) ethane, bis (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene N-butyl ether, glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

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

Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether and diethylene glycol dimethyl ether have a high solvation ability to lithium ion , And ion dissociation property. Particularly preferred are dimethoxymethane, diethoxymethane and ethoxymethoxymethane in view of low viscosity and high ionic conductivity.

The compounding amount of the ether compound is usually not less than 0.3% by volume, preferably not less than 0.5% by volume, more preferably not less than 1% by volume, and preferably not less than 40% by volume, based on 100% by volume of the non- % Or less, more preferably 35 vol% or less, further preferably 30 vol% or less. When the range is within this range, it is easy to secure the effect of improving the ionic dissociation degree of the chain type ether and the ion conductivity derived from the decrease in viscosity, and when the negative electrode active material is a carbonaceous material, It is easy to avoid the situation that the capacity is lowered due to insertion.

<Sulfonic Compound>

As the sulfone compound, cyclic sulfone having 3 to 6 carbon atoms and chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.

As the cyclic sulfone, monosulfone compounds such as trimethylene sulfone, tetramethylene sulfone, and hexamethylene sulfone; Disulfone compounds such as trimethylene disulfone, tetramethylene disulfone, and hexamethylene disulfone. Among them, tetramethylene sulfone, tetramethylene disulfone, hexamethylene sulfone, and hexamethylene disulfone are more preferable, and tetramethylene sulfone (sulforanes) is particularly preferable from the viewpoint of the dielectric constant and viscosity.

As sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter sometimes abbreviated as "sulfolanes" including sulfolane) are preferable. As the sulfolane derivative, it is preferable that at least one of hydrogen atoms bonded on the carbon atom constituting the sulfolane ring is substituted with a fluorine atom or an alkyl group. Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2 , 4-difluorosulfurane, 2,5-difluorosulfurane, 3,4-difluorosulfurane, 2-fluoro-3-methylsulfolane, 2-fluoro- 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 , Fluoro-3- (trifluoromethyl) sulfolane, and 5-fluoro-3- (trifluoromethyl) sulfolane have high ionic conductivity and high input / output It is preferable in this regard.

Examples of the chain sulfone include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, methyl n-propyl sulfone, ethyl n-propyl sulfone, di- , Diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, fluoromethyl methyl sulfone, difluoromethyl methyl sulfone, (2-fluoro) ethylmethylsulfone, (2,2-difluoroethyl) methylsulfone, trifluoroethylmethylsulfone, pentafluoroethylmethylsulfone, ethylfluoromethylsulfone, ethyldifluoromethylsulfone, Ethyl (trifluoromethyl) sulfone, ethyl (trifluoromethyl) sulfone, ethyl trifluoromethylsulfone, perfluoroethyl methyl sulfone, ethyl (2,2,2-trifluoroethyl) sulfone, ethyl pentafluoroethyl sulfone, Ethyl) sulfone, fluoromethyl-n-propylsulfone, difluoromethyl-n-propylsulfone, trifluoromethyl-n-propyl Sulfosulfone, fluoromethyl-i-propylsulfone, difluoromethyl-i-propylsulfone, trifluoromethyl-i-propylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethyl- Sulfone, pentafluoroethyl-n-propylsulfone, pentafluoroethyl-i-propylsulfone, n-butyl (2,2,2-trifluoroethyl) sulfone, t- Fluoroethyl) sulfone, n-butyl pentafluoroethyl sulfone, and t-butyl pentafluoroethyl sulfone.

Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, methyl-n-propyl sulfone, methyl-i-propyl sulfone, methyl- (2-fluoroethyl) methylsulfone, (2, 2-difluoroethyl) methylsulfone, methyltrifluoroethylsulfone, methylpentafluoroethylsulfone, ethylfluoro Propyltrifluoromethylsulfone, i-propyltrifluoromethylsulfone, i-propyltrifluoromethylsulfone, i-propyltrifluoromethylsulfone, i-propyltrifluoromethylsulfone, n-butyltrifluoroethylsulfone, t-butyltrifluoroethylsulfone, n-butyltrifluoromethylsulfone, t-butyltrifluoromethylsulfone and the like are preferable because of their high ionic conductivity and high input and output.

The compounding amount of the sulfonic compound is usually not less than 0.3% by volume, preferably not less than 0.5% by volume, more preferably not less than 1% by volume, and preferably not more than 40% by volume, based on 100% by volume of the non- By volume or less, more preferably 35% by volume or less, further preferably 30% by volume or less. With such a range, it is easy to obtain an effect of improving the durability such as cycle characteristics and storage characteristics, and the viscosity of the non-aqueous liquid electrolyte can be set in an appropriate range to avoid deterioration of the electric conductivity. The charge / discharge capacity retention rate is liable to be avoided.

1-2. Electrolyte

<Lithium salt>

As the electrolyte, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used in this application, and any lithium salt can be used, and specific examples thereof include the following.

For example, inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiNbF ₆ , LiTaF ₆ , and LiWF ₇ ;

Lithium fluorophosphates such as LiPO ₃ F and LiPO ₂ F ₂ ;

Lithium tungstate 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 salts of carboxylic acids such as CO ₂ Li and 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 Sulfonic acid lithium salts such as CF ₂ CF ₂ SO ₃ Li;

_{LiN (FCO) 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 SO _{2) 2,} lithium cyclic 1,2-ethane disulfide perfluoroalkyl sulfonyl imide, lithium cyclic 1,3-perfluoro propane sulfonyl disulfonyl _{imide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2 ); _{LiC (FSO 2) 3, LiC} (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) methide lithium salts such as _3;

Lithium oxalato borate salts such as lithium difluorooxalato borate and lithium bis (oxalato) borate;

Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, and lithium tris (oxalato) phosphate;

In addition, it is possible to use 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- fluorinated organic lithium salts; And the like.

Among _{them, LiPF 6, LiBF 4, LiSbF} 6, LiTaF 6, 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-perfluoropropane disulfonylimide _{, LiC (FSO 2) 3,} LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3, lithium bis oxalato borate, lithium difluoro oxalato borate, lithium tetrafluoroborate oxalato Sat phosphate, lithium difluoro bis oxalato phosphate, lithium tris (oxalato) _{phosphate, LiBF 3 CF 3, LiBF 3} C 2 F 5, LiPF 3 (CF 3) 3, LiPF 3 (C 2 F 5) ₃ is particularly preferable because it has the effect of improving the output characteristics, high rate charge / discharge characteristics, high temperature storage characteristics, cycle characteristics, and the like.

These lithium salts may be used alone, or two or more of them may be used in combination. A preferred example of the case where two or more kinds are used in combination is LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F ₂ in combination, and has an effect of improving load characteristics and cycle characteristics. Of these, the combination of LiPF ₆ and FSO ₃ Li, and LiPF ₆ and LiPO ₂ F ₂ are preferable because of their remarkable effects.

When LiPF ₆ and LiBF ₄ and LiPF ₆ and FSO ₃ Li are used in combination, the concentration of LiBF ₄ or FSO ₃ Li relative to 100 mass% of the entire non-aqueous liquid electrolyte is not limited and the effect of the present invention is not significantly impaired But it is usually 0.01 mass% or more, preferably 0.1 mass% or more, and the upper limit thereof is usually 30 mass% or less, preferably 20 mass% or less, more preferably 20 mass% or less, The effects of the output characteristics, the load characteristics, the low temperature characteristics, the cycle characteristics, the high temperature characteristics and the like may be improved by setting the content to 10 mass% or less, more preferably 5 mass% or less. On the other hand, also in the case of using LiPF ₆ and LiPO ₂ F ₂ in combination, the concentration of LiPO ₂ F ₂ relative to 100 mass% of the entire non-aqueous liquid electrolyte is not particularly limited and may be arbitrary as long as it does not significantly impair the effect of the present invention Is usually not less than 0.001 mass%, preferably not less than 0.01 mass%, and the upper limit thereof is usually not more than 10 mass%, preferably not more than 5 mass%, with respect to the non-aqueous liquid electrolyte. In this range, the effects of the output characteristics, the load characteristics, the low temperature characteristics, the cycle characteristics, and the high temperature characteristics are improved. On the other hand, in an excessively large amount, there are cases where precipitation occurs at a low temperature to deteriorate the battery characteristics. When the amount is too small, the effect of improving low temperature characteristics, cycle characteristics, high temperature storage characteristics and the like may be deteriorated.

Here, when the LiPO ₂ F ₂ is contained in the electrolytic solution, the electrolytic solution is prepared by adding LiPO ₂ F ₂ synthesized by a known method to an electrolyte solution containing LiPF ₆ , a method of forming a battery such as an active material or an electrode plate And LiPO ₂ F ₂ is generated in the system when the battery is assembled by using an electrolytic solution containing LiPF _{6. In the} present invention, any method may be used.

The method for measuring the content of LiPO ₂ F _{2 in} the above non-aqueous liquid electrolyte and non-aqueous liquid electrolyte secondary battery is not particularly limited and any publicly known method can be used, and specific examples thereof include ion chromatography, F Nuclear magnetic resonance spectroscopy (hereinafter, may be abbreviated as NMR), and the like.

Another example is the combination of an inorganic lithium salt and an organic lithium salt, and the combination of both has an effect of suppressing deterioration by high-temperature preservation. With an organolithium _{salt, 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-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalato borate, lithium difluorooxalato borate, lithium tetrafluorooxalato phosphate, lithium difluorobisoxalato phosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _{3, and the} like. In this case, the proportion of the organic lithium salt to 100 mass% of the total of the non-aqueous liquid electrolyte is preferably 0.1 mass% or more, particularly preferably 0.5 mass% or more, preferably 30 mass% or less, particularly preferably 20 mass% % Or less.

The concentration of these lithium salts in the non-aqueous liquid electrolyte is not particularly limited as long as the effect of the present invention is not impaired. However, from the viewpoint of ensuring a good battery performance by setting the electric conductivity of the liquid electrolyte to a favorable range, The total molar concentration of lithium is preferably 0.3 mol / l or more, more preferably 0.4 mol / l or more, still more preferably 0.5 mol / l or more, and further preferably 3 mol / l or less, Is 2.5 mol / l or less, and more preferably 2.0 mol / l or less. Within this range, effects such as low temperature characteristics, cycle characteristics, and high temperature characteristics are improved. On the other hand, if the total molar concentration of lithium is too low, the electric conductivity of the electrolytic solution may be insufficient. On the other hand, if the concentration is excessively high, the electric conductivity may be lowered in order to increase the viscosity, .

1-3. Supplements

In the non-aqueous liquid electrolyte secondary battery of the present invention, an auxiliary agent may be appropriately used depending on the purpose. Examples of the auxiliary agent include compounds having the following carbon-carbon triple bonds, cyclic carbonates having an unsaturated bond excluding the carbon-carbon triple bonds, unsaturated cyclic carbonates having a fluorine atom, cyclic sulfonic acid esters, A compound having an isocyanato group, and other auxiliary agents.

&Lt; Compound having carbon-carbon triple bond >

In the non-aqueous liquid electrolyte secondary battery of the present invention, a compound having a carbon-carbon triple bond may be contained in order to form a film on the surface of the negative electrode and to achieve longevity of the battery. The compound having a carbon-carbon triple bond is not particularly limited as long as it is a compound having a carbon-carbon triple bond, but it is classified into a chained compound having a carbon-carbon triple bond and a cyclic compound having a carbon- .

As the chained compound having a carbon-carbon triple bond, at least one alkyne derivative represented by the following general formula (11) or (12) is preferably used.

[Chemical Formula 16]

In the general formulas (11) ~ (12), R 11 ~ R 19 each independently represents a hydrogen, an aryl having 1 to 12 carbon atoms an alkyl group, having 3 to 6 carbon atoms a cycloalkyl group or having 6 to 12 of the, R ₁₂ and R ₁₃ , R ₁₅ and R ₁₆ , and R ₁₇ and R ₁₈ may combine with each other to form a cycloalkyl group having 3 to 6 carbon atoms. and x and y represent an integer of 1 or 2. Y ₁ and Y ₂ each represent any of the following formulas (13) and may be the same or different.

[Chemical Formula 17]

Z ₁ represents hydrogen, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms.

Among the compounds represented by the general formula (11), preferred are the compounds represented by the general formula (11), such as 2-propynylmethyl carbonate, 1-methylpropylmethylcarbonate, 1,1- Dimethyl-2-propinyl ethyl carbonate, 2-butynyl methyl carbonate, 1-methyl-2-butynyl methyl carbonate, 1,1-dimethyl- Methyl-2-propynyl, formic acid-1-methyl-2-propynyl, formic acid-1,1-dimethyl- Propyl, acetic acid-1-methyl-2-propynyl, acetic acid-1,1-dimethyl-2-propynyl, acetic acid 2- Methyl-2-butynyl, acetic acid-1,1-dimethyl-2-butynyl, 2-propynylmethyl oxalate, Dimethyl-2-propynylmethyl oxalate, 2-butynyl Methyl-2-butynylmethyl oxalate, 1,1-dimethyl-2-butynylmethyl oxalate, 2-propinyl ethyl oxalate, Methyl-2-butynyl ethyl oxalate, 1,1-dimethyl-2-propynyl ethyl oxalate, methanesulfonic acid Methyl-2-propynyl, methanesulfonic acid-1,1-dimethyl-2-propynyl, methanesulfonic acid 2-butynyl, methanesulfonic acid- 1-dimethyl-2-butynyl, trifluoromethanesulfonic acid-2-propynyl, trifluoromethanesulfonic acid-1-methyl-2-propynyl, trifluoromethanesulfonic acid- Dimethyl-2-propynyl, trifluoromethanesulfonic acid-2-butynyl, trifluoromethanesulfonic acid-1-methyl-2-butynyl, trifluoromethanesulfonic acid-1,1- 2-propynyl, trifluoroethanesulfonic acid-2-propynyl, Methyl-2-propynyl, trifluoroethanesulfonic acid-1,1-dimethyl-2-propynyl, trifluoroethanesulfonic acid-2-butynyl, trifluoroethanesulfonic acid- Butynyl, trifluoroethanesulfonic acid-1,1-dimethyl-2-butynyl, benzenesulfonic acid-2-propynyl, benzenesulfonic acid- Methyl-2-butynyl, benzenesulfonic acid-1,1-dimethyl-2-butynyl, p-toluenesulfonic acid-2-propynyl , p-toluenesulfonic acid-1-methyl-2-propynyl, p-toluenesulfonic acid-1,1-dimethyl-2-propynyl, p-toluenesulfonic acid- Methyl-2-propynyl, methylsulfuric acid-1,1-dimethyl-2-butynyl, 2-butynyl, p-toluenesulfonic acid- Methyl-2-butynyl, methylsulfuric acid-1,1-dimethyl-2-propynyl, ethylsulfuric acid-2-propyl 1-methyl-2-propynyl, ethylsulfuric acid-1,1-dimethyl-2-propynyl, ethyl- -1,1-dimethyl-2-butynyl are preferable.

Propylmethyl carbonate, 2-propynyl methyl carbonate, 2-butynyl methyl carbonate, formic acid-2-propyl methyl carbonate, Propyl, formyl-1-methyl-2-propynyl, formyl-2-propynyl, , 1-dimethyl-2-propynyl acetate, 2-butynyl acetate, 2-propynyl methyl oxalate, Methanesulfonic acid-1-methyl-2-propynyl, methanesulfonic acid-1,1-dimethyl-2-propynyl, methanesulfonic acid- Methyl-2-butynyl, methylsulfuric acid-1-methyl-2-propynyl, methylsulfuric acid-1,1-dimethyl-2-propynyl , Methyl-2-butynylsulfate, and methyl-2- It is particularly preferred.

Among the compounds represented by the general formula (2), di (2-propynyl) carbonate, di (2-butynyl) carbonate, di Di (2-propynyl) carbonate, di (2-propynyl) oxalate, di (2-butynyl) ) Oxalate, di (1-methyl-2-propynyl) oxalate, di (1-methyl- (1-methyl-2-propynyl) oxalate, di (2-propynyl) sulfite, di Dimethyl-2-butynyl) sulfite, di (1, 1-dimethyl-2-propynyl) sulfite, di ) Sulfuric acid, di (1-methyl-2-propynyl) sulfuric acid, di (1, ) Sulfuric acid, from di (1,1-dimethyl-2-butynyl) sulfuric acid (2-propynyl) oxalate, di (2-butynyl) oxalate, di (2-propynyl) oxalate, (2-propynyl) sulfuric acid, and di (2-butynyl) sulfuric acid.

Of the above alkyne derivatives, the most preferred compounds are 2-propynylmethylcarbonate, 2-propynylethylcarbonate, 2-butynylmethylcarbonate, formic acid-2-propynyl, 2-butynyl, methanesulfonic acid-1-methyl-2-butynyl, methanesulfonic acid, 2- (2-propynyl) carbonate, di (2-propynyl) oxalate, di (2-propynyl) -Butyryl) oxalate, di (2-propynyl) sulfuric acid, and di (2-butynyl) sulfuric acid.

The compounds represented by the general formulas (11) to (12) may be used alone or in combination of two or more in any combination. The compounding amount of the compounds represented by the general formulas (11) to (12) is not particularly limited and is arbitrary as long as it does not significantly impair the effect of the present invention. The compounding amount of the compounds represented by the general formulas (11) to (12) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, further preferably 0.1% by mass or more in 100% by mass of the non-aqueous liquid electrolyte , Further preferably not more than 5 mass%, more preferably not more than 4 mass%, further preferably not more than 3 mass%. Within this range, it is easy to avoid the situation that the non-aqueous liquid electrolyte secondary battery is easy to exhibit sufficient cycle characteristics improving effect, the high temperature storage characteristics are lowered, the gas generation amount is increased, and the discharge capacity retention rate is lowered. On the other hand, if it is too small, the effect of the present invention may not be sufficiently exhibited, and if it is excessively large, the resistance may increase and the output or the load characteristic may be deteriorated.

The cyclic compound having a carbon-carbon triple bond is preferably a compound represented by the following general formula (14).

[Chemical Formula 18]

(In the general formula (14), X and Z represent CR ¹ ₂ , C═O, C═NR ¹ , C═PR ¹ , O, S, NR ¹ and PR ¹ , is _{^{CR 1 2, C = O,}} S = O, S (= O) 2, P (= O) -R 2, P (= O) represents the -OR ^3. wherein, R and R ¹ is hydrogen, R ² is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, R ³ is Li, NR ⁴ ₄ , or a halogen atom, Or a hydrocarbon group of 1 to 20 carbon atoms which may have a substituent R ⁴ is a hydrocarbon group of 1 to 20 carbon atoms which may have a substituent and may be the same or different from each other, W has the same meaning as R above, and may be the same as or different from R.)

In the general formula (14), X and Z are not particularly limited as long as they are in the range described in the above-mentioned general formula (4), but CR ¹ ₂ , O, S and NR ¹ are more preferable. In addition, Y is also in a range given in the general formula (14) is not particularly limited, preferably C = O, S = O, S (= O) 2, P (= O) -R 2, P (= O) -OR &lt; ³ &gt; is more preferable. R and R ¹ are not particularly limited as long as they are in the range described in the general formula (14), but preferably include hydrogen, fluorine, a saturated aliphatic hydrocarbon group which may have a substituent, an unsaturated aliphatic hydrocarbon group which may have a substituent, An aromatic hydrocarbon group.

R ² and R ⁴ are not particularly limited as long as they are in the range described in the general formula (14), but are preferably saturated aliphatic hydrocarbon groups which may have substituents, unsaturated aliphatic hydrocarbons which may have substituents, aromatic hydrocarbons Aromatic heterocyclic rings.

R ³ is not particularly limited as long as it is in the range described in the general formula (14), but is preferably Li, saturated aliphatic hydrocarbons which may have a substituent, unsaturated aliphatic hydrocarbons which may have a substituent, aromatic hydrocarbons which may have a substituent The ring can be heard.

The substituent of the saturated aliphatic hydrocarbon which may have a substituent, the unsaturated aliphatic hydrocarbon which may have a substituent, the aromatic hydrocarbon which may have a substituent, and aromatic heterocyclic ring are not particularly limited, but halogen, carboxylic acid, Unsaturated aliphatic hydrocarbon group which may have a substituent, ester of an aromatic hydrocarbon group which may have a substituent, and the like, more preferably a halogen, a phenol group, Preferably, fluorine is preferred.

Specific examples of preferred saturated aliphatic hydrocarbons include methyl, ethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1-fluoroethyl, 2-fluoroethyl, 1,1-difluoroethyl, Trifluoroethyl group, a 2,2-difluoroethyl group, a 1,1,2-trifluoroethyl group, a 1,2,2-trifluoroethyl group, a 2,2,2-trifluoroethyl group, A cyclopentyl group, and a cyclohexyl group are preferable.

Preferred examples of the unsaturated aliphatic hydrocarbon include an ethynyl group such as an ethynyl group, a 1-fluoroethenyl group, a 2-fluoroethenyl group, a 1-methylethenyl group, a 2-propenyl group, Phenyl group, 3-fluoro-2-propenyl group, ethynyl group, 2-fluoroethynyl group, 2-propynyl group and 3-fluoro-2propynyl group are preferable.

Preferred examples of the aromatic hydrocarbon include a phenyl group, a 2-fluorophenyl group, a 3-fluorophenyl group, a 2,4-difluorophenyl group, a 2,6-difluorophenyl group, , And a 6-trifluorophenyl group are preferable.

Preferred examples of the aromatic heterocycle include a 2-furanyl group, a 3-furanyl group, a 2-thiophenyl group, a 3-thiophenyl group, a 1-methyl-2-pyrrolyl group and a 1-methyl-3-pyrrolyl group.

Of these, methyl, ethyl, fluoromethyl, trifluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, ethenyl, ethynyl and phenyl are preferable.

More preferably a methyl group, an ethyl group or an ethynyl group.

n and m are not particularly limited as long as they are in the range described in the general formula (14), but are preferably 0 or 1, and more preferably n = m = 1 or n = 1 and m = 0. The molecular weight is preferably 50 or more. Further, it is preferably 500 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous liquid electrolyte is easily ensured, and the effects of the present invention are easily exhibited sufficiently.

Further, in both of the reactivity and the stability of the compound represented by the general formula (14), R is preferably a hydrogen, fluorine or ethynyl group. In the case of other substituents, the reactivity is lowered, and the expected characteristics may be lowered. Further, in the case of halogen other than fluorine, the reactivity is excessively high, which may increase the side reaction.

It is preferable that the number of fluorine or ethynyl groups in R is within a total of 2 or less. If the number is too large, there is a fear that the compatibility with the electrolytic solution is deteriorated, and the reactivity is excessively high, which may increase the side reaction.

Of these, n = 1 and m = 0 are preferable. When both are 0, the stability is deteriorated due to the deformation of the rings, and the reactivity is excessively increased, which may increase side reactions. When n = 2 or more, or n = 1 or m = 1 or more, there is a possibility that the chain is more stable than the ring, and the initial characteristics may not be exhibited.

Also, in the formula, X and Z are more preferably CR ^&lt; ₁₂ &gt; Otherwise, the reactivity is excessively high, and the side reaction may increase.

The molecular weight is more preferably 100 or more, and still more preferably 200 or less. Within this range, the solubility of the general formula (14) in the non-aqueous liquid electrolyte can be further ensured, and the effects of the present invention are more easily expressed.

More preferably, R is hydrogen. In this case, there is a high possibility that the side reaction is most suppressed while maintaining expected characteristics. When Y is C = O or S = O, one of X and Z is O, Y is S (= O) ₂ , P (= O) -R ² , P ³ , it is preferable that X and Z are O or CH _2, or that one of X and Z is O and the other is CH ₂ . When Y is C = O or S = O, when X and Z are both CH ₂ , the reactivity is excessively high, which may increase the side reaction.

Specific examples of these compounds are shown below.

[Chemical Formula 19]

Of the compounds represented by the general formula (14), the compounds represented by the general formula (15) are preferable from the viewpoint of easiness of industrial production.

[Chemical Formula 20]

Y represents C═O, S═O, S (═O) ₂ , P (═O) -R ² , P (═O) -OR ³ in the formula (15). The compound having these preferable conditions is specifically described below.

[Chemical Formula 21]

The above-mentioned compounds having a carbon-carbon triple bond may be used singly or two or more of them may be used in any combination and ratio. The compounding amount of the compound having a carbon-carbon triple bond is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The compounding amount of the compound having a carbon-carbon triple bond is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, and most preferably 0.1% by mass or more in 100% by mass of the non- Is not more than 5 mass%, more preferably not more than 4 mass%, further preferably not more than 3 mass%. Within this range, it is easy to avoid the situation that the non-aqueous liquid electrolyte secondary battery is easy to exhibit sufficient cycle characteristics improving effect, the high temperature storage characteristics are lowered, the gas generation amount is increased, and the discharge capacity retention rate is lowered. On the other hand, if it is too small, the effect of the present invention may not be sufficiently exhibited, and if it is excessively large, the resistance may increase and the output or the load characteristic may be deteriorated.

<Cyclic carbonate having an unsaturated bond excluding the carbon-carbon triple bond>

In the non-aqueous liquid electrolyte secondary battery of the present invention, in order to form a coating film on the surface of the negative electrode and to achieve long life of the battery, a cyclic carbonate having an unsaturated bond excluding the compound having the carbon- Quot; unsaturated cyclic carbonate &quot;) may be used.

The unsaturated cyclic carbonate is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond, and any unsaturated carbonates can be used. It is also assumed that cyclic carbonates having aromatic rings are also included in the unsaturated cyclic carbonates.

Examples of the unsaturated cyclic carbonate include ethylene carbonate, vinyl carbonate, allyl carbonate, and catechol carbonate, which are substituted with vinylene carbonates, aromatic rings or substituents having carbon-carbon double bonds, phenyl carbonates, vinyl carbonates, allyl carbonates, have.

Examples of the vinylene carbonate include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinylvinylene carbonate, 4,5-vinyl Vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, and the like.

Specific examples of the ethylene carbonate substituted with a substituent having an aromatic ring or carbon-carbon double bond include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, Carbonate, 4-methyl-5-allylethylene carbonate, and the like.

Particularly preferable examples of the unsaturated cyclic carbonates include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, vinylvinylene carbonate, 4,5-vinylvinylene carbonate, allylvinylene carbonate, 4 , 5-diallylvinylene carbonate, vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, -Allylethylene carbonate, and 4-allyl-5-vinylethylene carbonate form a stable interfacial protective film, and are more preferably used.

The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as it does not significantly impair the effect of the present invention. The molecular weight is preferably 50 or more and 250 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous liquid electrolyte is easily ensured, and the effects of the present invention are easily exhibited sufficiently. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or more, and still more preferably 150 or less. The method for producing the unsaturated cyclic carbonate is not particularly limited, and it is possible to produce the unsaturated cyclic carbonate by arbitrarily selecting a known method.

The unsaturated cyclic carbonate may be used alone or in combination of two or more in any combination.

The amount of the unsaturated cyclic carbonate to be added is not particularly limited and is arbitrary as long as it does not significantly disturb the effect of the present invention. The amount of the unsaturated cyclic carbonate to be blended is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, further preferably 0.2 mass% or more, and preferably 5 mass% or more in 100 mass% % Or less, more preferably 4 mass% or less, further preferably 3 mass% or less. Within this range, it is easy to avoid the situation that the non-aqueous liquid electrolyte secondary battery is easy to exhibit sufficient cycle characteristics improving effect, the high temperature storage characteristics are lowered, the gas generation amount is increased, and the discharge capacity retention rate is lowered. On the other hand, if the amount is too small, the effect of the present invention may not be sufficiently exhibited, and in an excessively large amount, the resistance may increase and the output or the load characteristic may be deteriorated.

<Unsaturated cyclic carbonate having fluorine atom>

In the non-aqueous liquid electrolyte secondary cell of the present invention, it is also preferable to use an unsaturated cyclic carbonate having a fluorine atom (hereinafter sometimes abbreviated as &quot; fluorinated unsaturated cyclic carbonate &quot;). The number of fluorine atoms of the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. Among them, fluorine atoms are usually not more than 6, preferably not more than 4, and most preferably one or two fluorine atoms.

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

Examples of the fluorinated vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, Carbonate, 4-fluoro-5-vinylvinylene carbonate, and the like.

Examples of fluorinated ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4- Vinylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro Vinylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4 , 5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4- -Phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate and the like.

Particularly preferred examples of the fluorinated unsaturated cyclic carbonates include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, Fluoro-5-vinylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4- , 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro 4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene Carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate are more preferably used because they form a stable interface protective film do.

The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as it does not significantly inhibit the effect of the present invention. The molecular weight is preferably 50 or more and 250 or less. Within this range, the solubility of the fluorinated cyclic carbonate in the non-aqueous liquid electrolyte can be easily ensured, and the effect of the present invention is easily exhibited. The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and it is possible to produce the fluorinated unsaturated cyclic carbonate by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and still more preferably 200 or less.

The fluorinated unsaturated cyclic carbonate may be used alone or in combination of two or more in any combination.

The blending amount of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as it does not significantly disturb the effect of the present invention. The blending amount of the fluorinated unsaturated cyclic carbonate is usually 0.01 mass% or more, preferably 0.1 mass% or more, and more preferably 0.2 mass% or more, in 100 mass% of the non-aqueous liquid electrolyte, Is 5 mass% or less, more preferably 4 mass% or less, and further preferably 3 mass% or less. Within this range, it is easy to avoid the situation that the non-aqueous liquid electrolyte secondary battery is easy to exhibit sufficient cycle characteristics improving effect, the high temperature storage characteristics are lowered, the gas generation amount is increased, and the discharge capacity retention rate is lowered. On the other hand, if the amount is too small, the effect of the present invention may not be sufficiently exhibited, and in an excessively large amount, the resistance may increase and the output or the load characteristic may be deteriorated.

<Cyclic sulfonate ester>

In the non-aqueous liquid electrolyte secondary battery of the present invention, it is also preferable to use a cyclic sulfonic acid ester. The molecular weight of the cyclic sulfonic acid ester compound is not particularly limited and is arbitrary as long as it does not significantly impair the effect of the present invention. The molecular weight is preferably 100 or more and 250 or less. Within this range, the solubility of the cyclic sulfonic acid ester compound in the non-aqueous liquid electrolyte is easily ensured, and the effect of the present invention is easily exhibited. The method for producing the cyclic sulfonic acid ester compound is not particularly limited and can be produced by arbitrarily selecting a known method.

Examples of the cyclic sulfonic acid ester compound that can be used in the nonaqueous electrolyte secondary battery of the present invention include 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, Sulfone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro- Methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone , 1,5-pentane sultone, 1-fluoro-1,5-pentane sultone, 2-fluoro-1,5-pentane sultone, 3-fluoro- , 5-pentanesulfon, 5-fluoro-1,5-pentanesulfone, 1-methyl-1,5-pentanesulfone, 2- , 4-methyl-1,5-pentane sultone, and 5-methyl-1,5-pentane sultone;

Disulfonic acid ester compounds such as methylene methane disulfonate, ethylene methane disulfonate, and ethylene ethane disulfonate;

And the like.

Among these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro- Butane sultone, methylene methane disulfonate and ethylene methane disulfonate are preferred from the viewpoint of improving the preservation property, and 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 3-propanesultone, and 3-fluoro-1,3-propanesultone are more preferable.

It is also preferable to use a cyclic sulfonic ester having a carbon-carbon double bond. Examples of the cyclic sulfonic acid ester having a carbon-carbon double bond include 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro- Sulfone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene- 1-propene-1, 3-sultone, 3-methyl-1-propene- 1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro- 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 and the like.

Of these, 1-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone and 3-butene-1,4-sultone are more preferable.

The cyclic sulfonic acid ester compound may be used alone or in combination of two or more in any combination.

The amount of the cyclic sulfonic acid ester compound to be added to the whole non-aqueous liquid electrolyte is not particularly limited and may be any amount as long as it does not significantly impair the effect of the present invention. However, it is usually 0.001% by mass or more, , More preferably not less than 0.3 mass%, and usually not more than 10 mass%, preferably not more than 5 mass%, more preferably not more than 3 mass%. When the above range is satisfied, the effects of the output characteristics, the load characteristics, the low temperature characteristics, the cycle characteristics, the high temperature storage characteristics and the like are further improved.

&Lt; Compound having cyano group >

In the non-aqueous liquid electrolyte secondary battery of the present invention, it is also preferable to use a compound having a cyano group. Here, 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 a compound represented by the general formula (9) is more preferable.

[Chemical Formula 22]

In Formula (9), 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, ~ 10 V is the organic counterpart. V is an integer of 1 or more, and when V is 2 or more, T may be mutually the same or different.

The molecular weight of the compound having a cyano group is not particularly limited and is arbitrary as long as it does not significantly impair the effect of the present invention. The molecular weight is preferably 50 or more, more preferably 80 or more, further preferably 100 or more and 200 or less. Within this range, the solubility of the compound having a cyano group in the non-aqueous liquid electrolyte is easily ensured, and the effect of the present invention is easily exhibited. The method for producing a compound having a cyano group is not particularly limited, and a known method can be optionally selected.

Specific examples of the compound represented by the general formula (9) include, for example,

But are not limited to, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, laurethonitrile, 2-methylbutyronitrile, 2,2- dimethylbutyronitrile, hexanenitrile, cyclopentane 2-methyl-2-pentenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 2-methyl-2-pentenenitrile, 2-pentenenitrile, 2-hexenenitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3- Trifluoropropionitrile, 3,3'-oxy dipropionitrile, 3,3'-thiodipropionitrile, 3,3'-thiodipropionitrile, A compound having one cyano group such as 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, and pentafluoropropionitrile;

But are not limited to, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecaneditrile, dodecaneditrile, methylmalononitrile, ethylmalononitrile, i -Propyl malononitrile, t-butyl malononitrile, methyl succinonitrile, 2,2-dimethyl succinonitrile, 2,3-dimethyl succinonitrile, trimethyl succinonitrile, tetramethyl succinonitrile, 3,3 A compound having two cyano groups such as - (ethylene dioxy) dipropionitrile and 3,3 '- (ethylene dithio) 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 and heptyl cyanate;

Methyl thiocyanate, ethyl thiocyanate, propyl thiocyanate, butyl thiocyanate, pentyl thiocyanate, hexyl thiocyanate, heptyl thiocyanate, methanesulfonyl cyanide, ethanesulfonyl cyanide, propanesulfonyl There may be mentioned cyanide, butane sulfonyl cyanide, pentane sulfonyl cyanide, hexane sulfonyl cyanide, heptane sulfonyl cyanide, methyl sulfurocyanidate, ethyl sulfurocyanidate, propyl sulfurocyanidate, Sulfur compounds such as furocyanidate, pentylsulfurocyanidate, hexylsulfurocyanidate, and heptylsulfurocyanidate;

A cyanomethylphosphinic acid methyl, a cyanomethylphosphinic acid methyl, a dimethylphosphinic acid cyanide, a dimethyl aposphinic acid cyanide, a cyanophosphonate dimethyl, a cyanophosphonic acid Dimethylphosphoric acid, cyanomethylphosphonic acid, cyanomethylphosphonosaminomethyl, cyanodimethylphosphoric acid, and cyanodimethylphosphoric acid;

And the like.

among them,

But are not limited to, acetonitrile, propionitrile, butyronitrile, i-butyronitrile, valeronitrile, i-valeronitrile, launonitrile, crotononitrile, 3- methylcrotononitrile, malononitrile, But are not limited to, malononitrile, succinonitrile, glutaronitrile, butanone, and the like. More preferred are compounds having two cyano groups such as nitrile, adiponitrile, pimelonitrile, subbenonitrile, azelanitrile, sebaconitrile, undecaneditrile, and dodecaneditrile.

The compound having a cyano group may be used singly or two or more kinds may be used in any combination and proportion.

The amount of the compound having a cyano group in the non-aqueous liquid electrolyte is not particularly limited and may be any value as long as it does not significantly impair the effect of the present invention. The amount is usually 0.001% by mass or more, preferably 0.1% , More preferably not less than 0.3 mass%, and usually not more than 10 mass%, preferably not more than 5 mass%, more preferably not more than 3 mass%. When the above range is satisfied, the effects of the output characteristics, the load characteristics, the low temperature characteristics, the cycle characteristics, the high temperature storage characteristics and the like are further improved.

&Lt; Compound having an isocyanato group >

In the nonaqueous electrolyte secondary battery of the present invention, it is also preferable to use an isocyanate compound. Here, the compound having an isocyanato group is not particularly limited as long as it is a compound having an isocyanato group in the molecule,

Isocyanato-2-methoxyethane, isocyanato-1-propene, isocyanatocyclopropane, 2-isocyanatopropane, 1- Isocyanato-2-methylpropane, 1-isocyanato-3-methoxypropane, 1-isocyanato-3-ethoxypropane, Isocyanato-4-methoxybutane, 1-isocyanato-4-ethoxybutane, methylisocyanatoformate, isocyanatocyclopentane, 1-isocyanatopentane, 1- Isocyanatocyclohexane, 1-isocyanatohexane, 1-isocyanato-5-methoxypentane, isocyanato-5-methoxypentane, Isocyanato-6-ethoxyhexane, ethyl isocyanatoacetate, isocyanatocyclopentane, isocyanatomethyl (cyclohexane), monomethylene diisocyanate Butylene diisocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 1,3-dimethylene diisocyanate, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1-diisocyanato- Diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6- Diisocyanato-3, 4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanato Methyl) cyclohexane, 1,3-bis (isocyanatomethyl) (Isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexyl Methane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, iso Phlorone diisocyanate, buret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of formulas (10-1) to (10-4) ⁵ and R &lt; ⁶ &gt; are arbitrary hydrocarbon groups).

(23)

&Lt; EMI ID =

(25)

(26)

Among the compounds having an isocyanato group, a compound represented by the general formula (10-5) is preferable in order to form a good protective coating.

(27)

(Wherein A represents an organic group having 1 to 20 carbon atoms and composed of an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and n ' )

An organic group having 1 to 20 carbon atoms and composed of an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, An oxygen atom, a sulfur atom, a phosphorus atom, or an organic group which may contain a halogen atom. The organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom is an organic group in which a part of the carbon atoms of the skeleton is substituted by these atoms or an organic group having a substituent composed of these atoms it means.

The molecular weight of the compound represented by the general formula (10-5) is not particularly limited and is arbitrary as long as it does not significantly impair the effect of the present invention. The molecular weight is preferably 80 or more, more preferably 115 or more, further preferably 180 or more, and is 400 or less, and more preferably 270 or less. Within this range, the solubility of the compound represented by the general formula (10-5) in the non-aqueous liquid electrolyte can easily be ensured, and the effect of the present invention is easily exhibited. The method for producing the compound represented by the general formula (10-5) is not particularly limited, and a known method can be optionally selected.

Specific examples of A in the general formula (10-5) include, for example,

An alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, a cycloalkenylene group or a derivative thereof, an arylene group or a derivative thereof, a carbonyl group or a derivative thereof, An amide group or a derivative thereof, an imide group or a derivative thereof, an ether group or a derivative thereof, a thioether group or a derivative thereof, a boronic acid group or a sulfonate group or a derivative thereof, a sulfonyl group or a derivative thereof, a phosphonyl group or a derivative thereof, A derivative thereof, a borane group or a derivative thereof, and the like.

Of these, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, an arylene group or a derivative thereof are preferable from the viewpoint of improvement of the cell characteristics. It is more preferable that B is an organic group having 2 to 14 carbon atoms which may have a substituent.

Specific examples of the compound represented by formula (10-5) include monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, Heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 1,3-diisocyanatopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato- 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3, 4-difluoro Hexane, toluene diisocyanate, xylene diisocyanate, tolylene di (Isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2- Diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate , Dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, and basic structures of formulas (10-1) to Isocyanurate, adduct, and a bifunctional type of modified polyisocyanate. In the formula, R ⁵ and R ⁶ are each an arbitrary hydrocarbon group.

(28)

[Chemical Formula 29]

(30)

(31)

Of these, trimethylene diisocyanate, hexamethylene diisocyanate (HMDI), 1,3-bis (isocyanatomethyl) cyclohexane (BIMCH), dicyclohexylmethane-4,4'-diisocyanate, Isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of (1) to (10-4) are preferable in that a more stable film is formed.

The above-mentioned isocyanate compounds may be used singly or in combination of two or more in any combination and ratio.

The amount of the compound represented by the general formula (10-5) is not limited in the total amount of the non-aqueous liquid electrolyte, and it is not particularly limited so long as the effect of the present invention is not remarkably impaired, but is usually 0.001% Preferably not less than 0.01 mass%, more preferably not less than 0.1 mass%, further preferably not less than 0.2 mass%, and usually not more than 5 mass%, preferably not more than 4.0 mass%, more preferably not more than 3.0 mass% Or less, more preferably 2 mass% or less. When the content is within the above range, durability such as cycle, preservation and the like can be improved, and the effect of the present invention can be sufficiently exhibited.

<Other supplements>

In the nonaqueous electrolyte secondary battery of the present invention, other known auxiliary agents can be used. Other auxiliary agents include carbonate compounds such as erythritan carbonate, spiro-bis-dimethyl carbonate, methoxyethyl-methyl carbonate and the like; The present invention relates to an anhydrous succinic acid, anhydroglutaric acid, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, Carboxylic anhydrides such as anhydrides; Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; N, N-dimethylmethanesulfonamide, N, N-dimethylmethanesulfonamide, N, N-dimethylmethanesulfonamide, N, N-dimethylmethanesulfonamide, N, N-dimethylmethanesulfonamide, N, , And N-diethylmethanesulfonamide; Methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, Nitrogen compounds; Hydrocarbons such as heptane, octane, nonane, decane and cycloheptane; fluorinated aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride; Methyldimethylphosphinate, ethyldimethylphosphinate, ethyldiethylphosphinate, trimethylphosphonoformate, triethylphosphonoformate, trimethylphosphonoacetate, triethylphosphonoacetate, trimethyl-3-phosphonopropane Phosphonate, triethyl-3-phosphonopropionate, and the like. These may be used singly or in combination of two or more. By adding these auxiliary agents, capacity retention characteristics and cycle characteristics after high temperature storage can be improved.

Among them, a sulfuric acid such as ethylene sulfite, methyl fluorosulfonate, methyl methanesulfonate, methyl ethanesulfonate, ethyl methanesulfonate, bisulfate and 1,4-butanediol bis (2,2,2-trifluoroethanesulfonate) Compound is particularly preferable in that it has a large effect of improving capacity retention characteristics and cycle characteristics after high temperature storage.

The amount of the other adjuvants to be added is not particularly limited and is arbitrary as long as the effect of the present invention is not significantly impaired. The amount of the other auxiliary agent is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, still more preferably 0.2 mass% or more, and further preferably 5 mass% or less in 100 mass% of the non-aqueous liquid electrolyte, Is 3 mass% or less, and more preferably 1 mass% or less. Within this range, it is easy to easily elucidate the effects of other auxiliary agents, and the battery characteristics such as high load discharge characteristics are easily deteriorated.

The nonaqueous electrolytic solution described above includes those existing inside the nonaqueous electrolyte secondary battery of the present invention. Specifically, the components of the non-aqueous electrolytic solution such as the lithium salt, the solvent and the auxiliary are separately synthesized, the nonaqueous electrolytic solution is prepared from the substantially isolated one, and the solution obtained by pouring the solution into a cell assembled separately by the method described below When the non-aqueous liquid electrolyte in the non-aqueous liquid electrolyte secondary battery or the components of the non-aqueous liquid electrolyte according to the present invention are separately contained in the battery and mixed in the battery, when the same composition as that of the non-aqueous liquid electrolyte according to the present invention is obtained, Further, the present invention also includes a case where a compound constituting the non-aqueous liquid electrolyte according to the present invention is generated in the non-aqueous liquid electrolyte secondary cell to obtain the same composition as the non-aqueous liquid electrolyte according to the present invention.

The non-aqueous liquid electrolyte according to the present invention is preferably used as an electrolyte for a secondary battery in which the upper limit working potential of the positive electrode is 4.5 V or more, preferably 4.55 V or more, and more preferably 4.60 V or more based on Li / Li ⁺ do. On the other hand, the upper limit operating potential of the positive electrode is usually 5.05 V or less based on Li / Li ⁺ . In addition, as described in the embodiment of the present invention, when a battery in which the upper limit operating potential is set to be lower is used, the durability of the battery is improved, so that it may be preferable depending on the use of the battery.

2. Positive

&Lt; Positive electrode active material &

Hereinafter, the positive electrode active material used for the positive electrode will be described.

(Furtherance)

The positive electrode active material is not particularly limited as long as it is capable of intercalating and deintercalating lithium ions electrochemically. It is also possible to use a transition metal compound containing at least one metal element other than Li and Mn, at least Li, Ni, Co and / And a mixed valence transition metal compound containing at least one transition metal element having an average oxidation number of +4 and +3, respectively.

Specific examples of the transition metal compound include lithium transition metal compounds represented by the following general formulas (4) to (6).

Li [Li _a M _x Mn _{2- x a} ] O _{4 +} (4)

(Wherein 0? A? 0.3, 0.4 <x <1.1 and -0.5 <delta <0.5, and M is at least one of transition metals selected from Ni, Cr, Fe, )

Li _x M1 _y M2 _z O _2-delta ... (5)

(In the formula (5), 1? X? 1.3, 0? Y? 1, 0? Z? 0.3 and -0.1?? 0.1, M1 represents Ni, Co and / or Mn, M2 represents Fe , At least one element selected from Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, Ta, Be, Al, Ca, Sc and Zr )

αLi ₂ MO ₃ (1-α) LiM'O ₂ ... (6)

(In the formula (6), 0 < alpha < 1, M represents at least one of the metal elements having an average oxidation number of +4 and M 'represents at least one metal element having an average oxidation number of +3 )

As the transition metal of the lithium transition metal compound represented by the general formula (4), Ni, Cr, Mn, Fe, Co and Cu are preferable and specific examples include LiMn ₂ O ₄ , Li ₂ MnO ₄ , Li _{1 + a} Manganese composite oxide such as Mn ₂ O ₄ (a; 0 <a? 3.0), LiMn _x Ni _2-x O ₄ , Li _{1 + a} Mn _1.5 Ni _0.5 O ₄ Lithium-nickel-manganese composite oxides.

As the transition metal of the lithium transition metal compound represented by the general formula (5), V, Ti, Cr, Mn, Fe, Co, Ni and Cu are preferable. Specific examples thereof include lithium cobalt complex such as LiCoO ₂ Oxides, lithium-manganese composite oxides such as LiMnO _2, and lithium-nickel complex oxides such as LiNiO ₂ . In the formula (5), 0 ≤ y ≤ 1 and 0 ≤ z ≤ 0.3. When y and z are both 0, that is, when the transition metal is not contained, the compound represented by the general formula (5) And is not contained in the lithium transition metal compound.

A part of the transition metal atoms which are the main components of these lithium transition metal composite oxides are replaced with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Specific examples thereof include lithium-nickel-cobalt-aluminum composite oxide, lithium-cobalt-nickel composite oxide, lithium-cobalt-manganese composite oxide, lithium-nickel-manganese composite oxide, Lithium-nickel-cobalt-manganese composite oxide, and the like. Of these, lithium-nickel-manganese composite oxides and lithium-nickel-cobalt-manganese composite oxides are preferable because of good battery characteristics. For example, LiNi _x Mn _1-x O ₂ , LiNi _x Co _y Al _1-xy O ₂ , LiNi _x Co _y Mn _z O ₂ (x + y + z = 1), LiMn _x Al _2-x O ₄ , Li ₂ MO _3. (1-α) LiM'O ₂ (0 <α <1), Li ₂ MPO ₄ F, Li ₂ MSiO ₄ and LiMPO ₄ (M = Fe, Ni, Mn, Co) .

Specific examples of the substituents include 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 Mn _0.45 Co _0.1 O ₂ , Li _{1 + a} Ni _0.475 Mn _0.475 Co _0.05 O ₂ , Li _{1 + a} Mn _1.8 Al _0.2 O ₄ , x Li ₂ MnO ₃ (1-x) Li _{1 + a} MO ₂ where M is a transition metal and metals selected from the group consisting of Li, Ni, Mn and Co, a? 3.0). The ratio of these substitution metal elements in the composition formula is appropriately controlled by the relationship between the battery characteristics of the battery using the same and the cost of the material.

As the lithium transition metal compound, αLi ₂ MO _3. (1-α) LiM'O ₂ can be given as represented by the general formula (6). Wherein M is at least one kind of metal element having an average oxidation number of +4, preferably at least 1 selected from the group consisting of Mn, Zr, Ti, Ru, Re and Pt, And more preferably at least one member selected from the group consisting of Mn, Zr and Ti. M 'is at least one kind of metal element having an average oxidation number of +3, preferably at least one kind of metal element selected from the group consisting of V, Mn, Fe, Co and Ni, more preferably at least one element selected from Mn, Co And Ni. &Lt; IMAGE &gt;

Among these positive electrode active materials, it is more preferable to use the above-mentioned formula (4) and the above-mentioned formula (6), more preferably to use the above-mentioned formula (4) Which is preferable in view of the stability of the active material. Specifically, among the lithium transition metal compounds represented by the above general formula (4), lithium metal compounds such as LiMn _x Ni _2-x O ₄ and Li _{1 + a} Mn _1.5 Ni _0.5 O ₄ (a; 0 <a? 3.0) Nickel-manganese composite oxide is preferable from the viewpoints of the stability of the positive electrode active material and the charging capacity.

In the present invention, although not particularly limited, lithium-containing transition metal phosphate compounds are also preferably used as the positive electrode active material, and transition metals of the lithium-containing transition metal phosphate compounds include V, Ti, Cr, Mn, Fe, Cu and the like are preferable, and specific examples include iron phosphates such as LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ and LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ and these lithium transition metal phosphates One in which some of the transition metal atoms that are the subject of the compound are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb and Si And the like.

Including lithium phosphate in the positive electrode active material is preferable because continuous charging characteristics are improved. There is no limitation on the use of lithium phosphate, but it is preferable to use a mixture of the above positive electrode active material and lithium phosphate. The amount of lithium phosphate to be used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more with respect to the total amount of the positive electrode active material and lithium phosphate, Is 10 mass% or less, more preferably 8 mass% or less, and further preferably 5 mass% or less.

(Surface coating)

A material having a composition different from that of the positive electrode active material may be adhered to the surface of the positive electrode active material. Examples of surface adhesion materials include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide and bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, Sulphate such as aluminum sulfate, lithium carbonate, calcium carbonate, carbonate such as magnesium carbonate, carbon and the like.

These surface-adhering substances may be dissolved or suspended in a solvent and impregnated with the positive electrode active material, followed by drying; a method of dissolving or suspending a surface-adherent precursor in a solvent, impregnating the surface active substance precursor with the positive electrode active material, A method of adding it to the precursor of the positive electrode active material and firing it at the same time, or the like can be attached to the surface of the positive electrode active material. When carbon is attached, a method in which the carbonaceous material is mechanically attached later, for example, in the form of activated carbon may be used.

The amount of the surface-adhering substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, further preferably 10 ppm or more, and preferably 20% or less, as a lower limit, , More preferably 10% or less, and further preferably 5% or less. The surface adhesion substance can suppress the oxidation reaction of the electrolytic solution on the surface of the positive electrode active material and improve the battery life. However, when the adhesion amount is too small, the effect is not sufficiently manifested. The resistance may be increased.

In the present invention, a substance having a different composition from the surface of the positive electrode active material is also included in the &quot; positive electrode active material &quot;.

(shape)

The shape of the particles of the positive electrode active material may be massive, polyhedral, spherical, elliptical, plate, needle, columnar, and the like as conventionally used. In addition, primary particles may aggregate to form secondary particles.

(Tap density)

The tap density of the positive electrode active material is preferably 0.5 g / cm 3 or more, more preferably 0.8 g / cm 3 or more, and still more preferably 1.0 g / cm 3 or more. If the tap density of the positive electrode active material falls below the lower limit, the amount of dispersion medium required for forming the positive electrode active material layer increases, the amount of the conductive material and the binder required increases, the filling rate of the positive electrode active material to the positive electrode active material layer is restricted, The battery capacity may be limited. By using the composite oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. The larger the tap density is, the more preferable, and the upper limit is not particularly large. However, if the tap density is too large, diffusion of lithium ions using the electrolyte solution in the positive electrode active material layer becomes rate-limiting, Therefore, the upper limit is preferably 3.0 g / cm 3 or less, more preferably 2.7 g / cm 3 or less, still more preferably 2.5 g / cm 3 or less.

Further, in the present invention, the tap density is obtained as the powder filling density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass scalpel cylinder and tapped 200 times with a stroke of about 20 mm.

(Median diameter d ₅₀ )

The median diameter d ₅₀ (secondary particle size when primary particles are aggregated and forming secondary particles) of the lithium-nickel-cobalt-manganese composite oxide particles that can be contained in the positive electrode active material is preferably 0.3 μm or more, More preferably at least 0.8 mu m, most preferably at least 1.0 mu m, and the upper limit is preferably at most 30 mu m, more preferably at most 27 mu m, further preferably at most 25 mu m, most preferably at most 0.5 mu m Or less. If the ratio is less than the lower limit, the gauge density product may not be obtained. If the upper limit is exceeded, the diffusion of lithium in the particles takes time, which may lead to deterioration of battery performance, There is a case where when a material or binder or the like is slurried with a solvent and applied in the form of a thin film, there arises a problem such as streaks. Here, by mixing two or more of the positive electrode active materials having different median diameters d ₅₀ , the filling property at the time of producing the positive electrode can be further improved.

In the present invention, the median diameter d ₅₀ is measured by a known laser diffraction / scattering type particle size distribution measuring apparatus. When LA-920 manufactured by HORIBA Co., Ltd. is used as the particle size distribution meter, the measurement is performed by setting a measurement refractive index of 1.24 after ultrasonic dispersion for 5 minutes using 0.1 mass% aqueous solution of sodium hexametaphosphate as a dispersion medium used for measurement.

(Median diameter d ₉₀ )

The median diameter of the lithium-nickel-manganese composite oxide which can be contained in the positive electrode active material is usually 2 m or more, preferably 2.5 m or more, more preferably 3 m or more, still more preferably 3.5 m or more, Is not less than 4 mu m and is usually not more than 60 mu m, preferably not more than 50 mu m, more preferably not more than 40 mu m, further preferably not more than 30 mu m, and most preferably not more than 20 mu m. If the median diameter is less than this lower limit, there is a possibility of causing a problem in coating property at the time of forming the positive electrode active material layer, and if the median diameter is more than the upper limit, there is a possibility that battery performance is deteriorated.

The 90% cumulative diameter (D ₉₀ ) of the secondary particles of the lithium-nickel-manganese composite oxide that can be contained in the positive electrode active material is usually 30 μm or less, preferably 25 μm or less, more preferably 22 μm or less, Most preferably 20 mu m or less, and usually 3 mu m or more, preferably 4 mu m or more, more preferably 5 mu m or more, and most preferably 6 mu m or more. If the 90% cumulative diameter (D ₉₀ ) exceeds the upper limit, there is a possibility that the battery performance is lowered. If the 90% cumulative diameter (D ₉₀ ) is less than the lower limit, there is a possibility that the coating property at the time of forming the positive electrode active material layer may be deteriorated.

In the present invention, the median diameter and the 90% cumulative diameter (D ₉₀ ) as the average particle size can be measured with a known laser diffraction / scattering particle size distribution measuring apparatus by setting the refractive index at 1.60 and measuring the particle size standard on the volume basis . In the present invention, measurement was carried out using 0.1 mass% aqueous solution of sodium hexametaphosphate as the dispersion medium used in the measurement.

(Average primary particle diameter)

In the lithium-nickel-cobalt-manganese composite oxide which can be contained in the positive electrode active material, when the primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, More preferably not less than 0.1 占 퐉, more preferably not less than 0.2 占 퐉, and the upper limit is preferably not more than 5 占 퐉, more preferably not more than 4 占 퐉, further preferably not more than 3 占 퐉, and most preferably not more than 2 占 퐉 . When the upper limit is exceeded, it is difficult to form spherical secondary particles, and adversely affecting the powder packing property or the specific surface area is largely lowered, so that there is a high possibility that the battery performance such as output characteristics is deteriorated. On the other hand, if the lower limit is below the lower limit, there is a case where the reversibility of charging and discharging is inferior because crystals are not normally developed.

The average diameter (average primary particle diameter) of the lithium-nickel-manganese composite oxide that can be contained in the positive electrode active material is not particularly limited, but the lower limit is preferably 0.1 占 퐉 or more, more preferably 0.2 占 퐉 or more, Preferably not more than 3 mu m, more preferably not more than 2 mu m, further preferably not more than 1.5 mu m, and most preferably not more than 1.2 mu m. If the average primary particle diameter exceeds the upper limit, there is a possibility that the battery performance such as the rate characteristic and the output characteristic may be lowered because the powder filling property is adversely affected or the specific surface area is lowered. If the lower limit is exceeded, there is a possibility that the reversibility of charging and discharging is deteriorated because crystals are not generated.

In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, it is determined by taking a maximum value of the intercept by the left and right boundary lines of the primary particle with respect to the straight line in the horizontal direction with respect to arbitrary 50 primary particles and taking an average value with a photograph with a magnification of 10,000 times.

(BET specific surface area)

The BET specific surface area of the lithium-nickel-cobalt-manganese composite oxide that can be contained in the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2 m 2 / g or more, still more preferably 0.3 m 2 / g or more And the upper limit thereof is not more than 50 m 2 / g, preferably not more than 40 m 2 / g, more preferably not more than 30 m 2 / g. When the BET specific surface area is smaller than this range, the battery performance tends to be deteriorated, and when the BET specific surface area is large, the tap density is not increased sufficiently, and there is a case that the coating property at the time of forming the positive electrode active material layer is apt to occur.

The lithium-nickel-manganese composite oxide that can be contained in the positive electrode active material may also have a BET specific surface area of usually 0.2 m 2 / g or more, preferably 0.3 m 2 / g or more, more preferably 0.35 m 2 / g or more, G or more, usually 3 m 2 / g or less, preferably 2.5 m 2 / g or less, more preferably 2 m 2 / g or less, and most preferably 1.5 m 2 / g or less. If the BET specific surface area is smaller than this range, the battery performance tends to deteriorate. If the BET specific surface area is large, the bulk density may not be sufficiently increased, and the energy density as a positive electrode active material may not be improved.

Further, the BET specific surface area can be measured by a known BET type powder specific surface area measuring apparatus. In the present invention, the BET 1-point method was measured by the continuous flow method using nitrogen as the adsorption gas and helium as the carrier gas, using an automatic powder specific surface area measuring apparatus of the type AMS8000 manufactured by Okura Riken. Specifically, the powder sample is heated and deaerated at a temperature of 150 ° C by a mixed gas, and then cooled to a liquid nitrogen temperature to adsorb the mixed gas. The mixed gas is then heated to room temperature by water to desorb the adsorbed nitrogen gas, The amount was detected by a heat conduction detector, and the specific surface area of the sample was calculated from the result.

(Production method of positive electrode active material)

As a method for producing the positive electrode active material, a general method is used as a method for producing an inorganic compound. In particular, various methods are conceivable for preparing spherical or elliptic spherical active materials. For example, raw materials of transition metals are dissolved or pulverized and dispersed in a solvent such as water, and pH is adjusted while stirring to prepare spherical precursors And then drying it as necessary, followed by addition of an Li source such as LiOH, Li ₂ CO ₃ , LiNO _3, etc., followed by calcination at a high temperature to obtain an active material. It is also possible to prepare a slurry preparation in which a lithium compound and at least one transition metal compound selected from Mn, Ni, Cr, Fe, Co and Cu and the additive of the present invention are pulverized in a liquid medium to obtain a slurry in which these are uniformly dispersed A spray drying step of spray drying the obtained slurry, and a sintering step of sintering the obtained spray dried body, according to the method for producing a lithium transition metal compound for a lithium secondary battery positive electrode material of the present invention.

For the production of the positive electrode, the above-mentioned positive electrode active material may be used singly or at least one of different compositions may be used in any combination or in any ratio. In this case, a preferable combination is LiMn ₂ O ₄ such as LiCoO ₂ and LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , or a combination of a part of the Mn substituted with another transition metal or the like, or a combination of LiCoO ₂ or a part of Co With another transition metal or the like.

&Lt; Composition and Manufacturing Method of Positive Electrode >

Hereinafter, the configuration of the positive electrode will be described. In the present invention, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. The positive electrode using the positive electrode active material can be produced by a conventional method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickening agent are dry-mixed and formed into a sheet form is pressed onto a positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to form a slurry, And the positive electrode active material layer is formed on the current collector by applying the negative electrode active material layer to the collector and drying the positive electrode active material layer.

The content of the positive electrode active material in the positive electrode active material layer is preferably 80 mass% or more, more preferably 82 mass% or more, and particularly preferably 84 mass% or more. The upper limit is preferably 99 mass% or less, and more preferably 98 mass% or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity sometimes becomes insufficient. Conversely, if the content is excessively large, the strength of the positive electrode may be insufficient.

The positive electrode active material layer obtained by coating and drying is preferably compacted by a hand press, a roller press or the like in order to increase the filling density of the positive electrode active material. The density of the positive electrode active material layer is preferably at least 1.5 g / cm 3, more preferably at least 2 g / cm 3, even more preferably at least 2.2 g / cm 3 as the lower limit, and preferably at most 5 g / , More preferably not more than 4.5 g / cm 3, still more preferably not more than 4 g / cm 3. If it exceeds this range, the permeability of the electrolytic solution to the vicinity of the current collector / active material interface is lowered, and in particular, the charge / discharge characteristics at a high current density are lowered and high output can not be obtained in some cases. On the other hand, if it is lower than the above range, the conductivity between the active materials is lowered, and the battery resistance is increased, so that high output may not be obtained.

(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 such as natural graphite and artificial graphite (graphite); Carbon black such as acetylene black; And carbon materials such as amorphous carbon such as needle coke. These may be used singly or in combination of two or more in any combination and ratio. The conductive material is usually 0.01 mass% or more, preferably 0.1 mass% or more, more preferably 1 mass% or more, and the upper limit is usually 50 mass% or less, preferably 30 mass% or less, in the positive electrode active material layer By mass, more preferably not more than 15% by mass. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may be lowered.

(Binder)

The binder used in the production of the positive electrode active material layer is not particularly limited and may be any material that dissolves or disperses in the liquid medium used in the electrode production in the case of the coating method and examples thereof include polyethylene, Resin type polymers such as polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; Rubber-like polymers such as SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber and ethylene-propylene rubber; Styrene-butadiene-styrene block copolymer or hydrogenated product thereof, EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-ethylene copolymer, styrene-isoprene-styrene block copolymer or hydrogenated product thereof Thermoplastic elastomer-based polymers; Soft dendritic polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer and propylene -olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymer; And polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions). These substances may be used alone or in combination of two or more in any combination.

The proportion of the binder in the positive electrode active material layer is usually 0.1 mass% or more, preferably 1 mass% or more, more preferably 1.5 mass% or more, and the upper limit is usually 80 mass% or less, preferably 60 mass % Or less, more preferably 40 mass% or less, and most preferably 10 mass% or less. If the ratio of the binder is too low, the positive electrode active material can not be sufficiently retained, and the mechanical strength of the positive electrode is insufficient, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, the battery capacity and the conductivity may be deteriorated.

(Slurry forming solvent)

The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the positive electrode active material, the conductive material, the binder, and the thickening agent to be used if necessary. The solvent is not limited to any of the aqueous solvent and the organic solvent May be used. Examples of the aqueous medium include water, a mixture of alcohol and water, and the like. The organic medium includes, for example, 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, methyl ethyl ketone, and cyclohexanone; Esters such as methyl acetate and methyl acrylate; Amines such as diethylenetriamine and N, N-dimethylaminopropylamine; Ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); Amides such as N-methylpyrrolidone (NMP), dimethylformamide and dimethylacetamide; And aprotic polar solvents such as hexamethylphosphoramide and dimethylsulfoxide.

Particularly, in the case of using an aqueous medium, it is preferable to make a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). The thickener is typically used to prepare the viscosity of the slurry. Specific examples of the thickening agent include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, starch starch, phosphoryl starch, casein, and salts thereof. These may be used singly or in combination of two or more in any combination. When the thickener is added, the ratio of the thickener to the active material is 0.1 mass% or more, preferably 0.2 mass% or more, more preferably 0.3 mass% or more, and the upper limit is 5 mass% Is not more than 3% by mass, more preferably not more than 2% by mass. Below this range, the coating property may remarkably decrease. The ratio of the active material occupied in the positive electrode active material layer is lowered to lower the capacity of the battery and there is a problem that the resistance between the positive electrode active materials increases.

(Whole house)

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; Carbon cloth, and carbon paper. Among them, a metal material, particularly aluminum, is preferable.

Examples of the shape of the collector include a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal and a foamed metal. Examples of the shape of the collector include a carbon plate, Carbon circumference and the like. Among these, a metal thin film is preferable. Further, the thin film may be appropriately formed in a mesh form. Thickness of the thin film is arbitrary, but is usually not less than 1 mu m, preferably not less than 3 mu m, more preferably not less than 5 mu m, and the upper limit is usually not more than 1 mm, preferably not more than 100 mu m, Mu m or less. If the thin film is thinner than this range, the required strength as a current collector may be insufficient. On the other hand, if the thin film is thicker than this range, the handling properties may be deteriorated.

It is also preferable that the surface of the current collector is coated with a conductive auxiliary agent from the viewpoint of reducing the electric contact resistance between the current collector and the positive active material layer. Examples of the conductive auxiliary agent include noble metals such as carbon, gold, platinum and silver.

The ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, but it is preferable that the value of (the thickness of the positive electrode active material layer on one side immediately before electrolyte injection and the thickness of the current collector) is 20 or less, more preferably 15 Or less, most preferably 10 or less, and the lower limit is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If this range is exceeded, the current collector may generate heat due to the joule heat at the time of high current density charge / discharge. Below this range, the volume ratio of the current collector to the positive electrode active material increases, and the capacity of the battery may decrease.

(Electrode area)

In the nonaqueous electrolyte secondary battery of the present invention, it is preferable that the area of the positive electrode active material layer is made larger with respect to the outer surface area of the battery case, from the viewpoint of enhancing the stability at the time of high output and high temperature. Specifically, it is preferable that the total area of the electrode areas of the positive electrode with respect to the surface area of the sheath of the secondary battery is 15 times or more, more preferably 40 times or more. The outer surface area of the outer case refers to the total area obtained by calculation from the length, width, and thickness of the case portion filled with the power generating element excluding the protruding portion of the terminal, in the case of a square shape. In the case of the user cylindrical shape, the geometric surface area approximating the case portion filled with the power generation elements excluding the projecting portion of the terminal as a cylinder. The total sum of the electrode areas of the positive electrode means a geometric surface area of the positive electrode mixture layer opposite to the negative electrode active material layer containing the negative electrode active material and a structure in which the positive electrode material layer is formed on both surfaces via the current collector foil, Is the total sum of the areas.

(Thickness of positive electrode plate)

The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the laminated material layer excluding the thickness of the metal foil of the core material is preferably not less than 10 占 퐉, more preferably not less than 20 占 퐉 And the upper limit thereof is preferably 500 占 퐉 or less, and more preferably 450 占 퐉 or less.

(Surface coating of positive electrode plate)

A material having a composition different from that of the positive electrode plate may be adhered to the surface of the positive electrode plate. Examples of surface adhesion materials include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide and bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, Sulphate such as aluminum sulfate, lithium carbonate, calcium carbonate, carbonate such as magnesium carbonate, carbon and the like.

3. Negative electrode

The negative electrode active material used for the negative electrode will be described below. The negative electrode active material is not particularly limited as long as it can electrochemically store and release lithium ions. Specific examples thereof include carbonaceous materials, alloy materials, , It is preferable to contain at least one negative electrode active material composed of graphite particles having a rhombohedral constant of 0% or more and 35% or less. These may be used singly or in combination of two or more.

&Lt; Negative electrode active material &

Examples of the negative electrode active material include a carbonaceous material, an alloy-based material, a lithium-containing metal complex oxide material, and a mixture thereof.

As the carbonaceous material used as the negative electrode active material,

(1) natural graphite,

(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous substance and an artificial graphite substance at least once in the range of 400 to 3200 ° C,

(3) a carbonaceous material having a negative electrode active material layer composed of carbonaceous materials having at least two different crystallizations and / or having an interface at which different crystalline carbonaceous materials are in contact,

(4) The carbonaceous material as described in any one of (1) to (4), wherein the negative electrode active material layer is composed of a carbonaceous material having at least two different orientations and /

Is preferable because of good balance between the initial irreversible capacity and the high current density charge / discharge characteristics. The carbonaceous materials (1) to (4) may be used singly or in combination of two or more in any combination.

Examples of the artificial carbonaceous material and artificial graphite material of (2) include natural graphite, coal-based coke, petroleum coke, coal-based pitch, petroleum-based pitch and those obtained by oxidizing these pitches, needle coke, pitch coke, Pyrolysis products of organic materials such as graphitized carbon materials, furnace black, acetylene black and pitch-based carbon fibers, carbonizable organic substances, carbides thereof, or carbonizable organic substances are mixed with benzene, toluene, xylene, quinoline, In a low-molecular organic solvent, and carbides thereof.

Examples of the alloy-based material used as the negative electrode active material include lithium metal, a single metal and an alloy forming the lithium alloy, or a compound such as an oxide, a carbide, a nitride, a silicide, a sulfide, or a phosphide thereof And is not particularly limited. As the single metal and the alloy forming the lithium alloy, it is preferable to be a material containing a group 13 and group 14 metal and semi-metal elements (i.e., excluding carbon), more preferably aluminum, silicon and tin , &Quot; specific metal element &quot;), and alloys or compounds containing these atoms.

As the negative electrode active material having at least one kind of atom selected from a specific metal element, it is possible to use a metal single element of any one specific metallic element, an alloy composed of two or more kinds of specific metallic elements, A compound containing one or more kinds of metal elements and a compound containing one or two or more kinds of specific metal elements and a complex compound such as an oxide, a carbide, a nitride, a silicide, a sulfide or a phosphide of the compound have. By using these metals, alloys or metal compounds as the negative electrode active material, it is possible to increase the capacity of the battery.

A compound in which these complex compounds are complexly bonded with various kinds of elements such as a metal single crystal, an alloy or a non-metallic element is also enumerated. Specifically, for example, in the case of silicon or tin, an alloy of these elements and a metal that does not work as a negative electrode can be used. For example, in the case of tin, a complicated compound containing 5 to 6 kinds of elements in combination of a metal serving as a negative electrode in addition to tin and silicon, a metal not acting as a negative electrode, and a non-metal element can also be used.

Of these negative electrode active materials, a single metal of one kind of specific metal element, an alloy of two or more kinds of specific metal elements, an oxide, a carbide, a nitride and the like of a specific metal element are preferable in view of large capacity per unit mass In particular, a metal group, an alloy, an oxide, a carbide or a nitride of silicon and / or tin is preferable in view of capacity per unit mass and environmental load.

The lithium-containing metal complex oxide material used as the negative electrode active material is not particularly limited as long as lithium can be intercalated and deintercalated, but a material containing titanium and lithium is preferable from the viewpoint of high current density charge-discharge characteristics, Containing composite metal oxide material is preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as &quot; lithium titanium composite oxide &quot;) is preferable. That is, when the lithium-titanium composite oxide having a spinel structure is contained in the negative electrode active material for a non-aqueous liquid electrolyte secondary battery, the output resistance is particularly reduced.

The lithium or titanium of the lithium-titanium composite oxide may be at least one selected from the group consisting of other metal elements, for example, Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, It is also preferable that it is substituted with an element of species.

Wherein the metal oxide is a lithium-titanium composite oxide represented by the general formula (A), 0.7? X? 1.5, 1.5? Y? 2.3 and 0? Z? 1.6 in the general formula (A) It is preferable that the structure of the hour is stable.

Li _x Ti _y M _z O ₄ ... (A)

(In the general formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu,

Among the compositions represented by the above general formula (A)

(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

Is particularly preferable because of the good balance of battery performance.

A particularly preferred typical composition of the compound is Li ₄ Ti ₃ O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b) and Li _4/5 Ti _11/5 O ₄ in (c) . With respect to the structure of Z? 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.

[Rectangular ratios]

The ratios of the rhombus bodies defined in the present invention can be calculated from the ratio of the graphite layer (ABC stacking layer) and the hexagonal structure graphite layer (AB stacking layer) by the X-ray wide angle diffraction (XRD) Can be obtained.

(%) = Integral intensity of ABC (101) peak of XRD ÷ AB (101) peak integral intensity of XRD × 100

Here, the ratios of the graphite particles of the present invention are usually 0% or more, preferably 0% or more, more preferably 3% or more, still more preferably 5% or more, particularly preferably 12% , And usually not more than 35%, preferably not more than 27%, more preferably not more than 24%, particularly preferably not more than 20%. Here, the rhombohedral constant of 0% means that no XRD peak derived from the ABC stacking layer is detected at all. Also, "greater than 0%" means that even a slight XRD peak originating from the ABC stacking layer is detected.

If the ratios of the rhombohedral crystals are excessively large, the crystal structure of the graphite particles contains a large amount of defects, so that the insertion amount of Li tends to decrease and it is difficult to obtain a high capacity. In addition, since the electrolytic solution is decomposed during the cycle due to the above defects, the cycle characteristics tend to be lowered. On the other hand, if the rhombohedral constant is within the range of the present invention, for example, the crystal structure of the graphite particles is less deficient and reactivity with the electrolyte is small, and consumption of the electrolytic solution in the cycle is small.

The XRD measurement method for obtaining the rhombohedral constant is as follows.

The graphite powder is filled in a sample plate of 0.2 mm so as not to be oriented and measured by an X-ray diffractometer (for example, output 45 kV, CuK? Line by X 'Pert Pro MPD manufactured by PANalytical Corporation). Using the obtained diffraction pattern, the peak integral intensity is calculated by the profile fitting using the asymmetric Pearson VII function using the analysis software JADE 5.0, and the ratios of the ratios of the peaks are calculated from the above equation.

The X-ray diffraction measurement conditions are as follows. Further, &quot; 2 &amp;thetas; &quot; indicates a diffraction angle.

· Target: Cu (Kα line) graphite monochrometer

Slit:

  Solar slit 0.04 degree

  Divergence slit 0.5 degree

  Lateral radiating mask 15 mm

  Scattering prevention slit 1 degree

· Measuring range and step angle / measuring time:

 (101) plane: 41 degrees? 2?? 47.5 degrees 0.3 degrees / 60 seconds

· Background correction: Connect a straight line between 42.7 and 45.5 degrees and subtract it in the background.

· Peak of rhombohedral structure graphite particle layer: Peak in the vicinity of 43.4 degrees.

· Peak of hexagonal structure graphite particle layer: Peak in the vicinity of 44.5 degrees.

The method of obtaining graphite particles having a rhombohedral constant of the above range can be adopted by a method of producing by using a conventional technique and is not particularly limited. However, it is preferable to produce graphite particles by heat treatment at a temperature of 500 캜 or more Do. It is also preferable to impart mechanical effects such as compression, friction, and shearing force to the graphite particles, including the interaction of particles mainly with an impact force. In addition, it is possible to adjust the rhombohedral constant by changing the intensity of the mechanical action, the processing time, and the presence or absence of repetition. Specific examples of the apparatus for adjusting the rhombohedral ratios include a rotor in which a plurality of blades are provided in a casing, and the rotor is rotated at a high speed, so that the carbon material introduced therein is subjected to mechanical actions such as impact compression, friction, To perform the surface treatment is preferable. It is also preferable to have a mechanism that repetitively imparts mechanical action by circulating a carbon material, or a mechanism that does not have a circulating mechanism but processes a plurality of devices connected and processed. As an example of a preferable apparatus, a hybridization system manufactured by Nara Machinery Co., Ltd. can be mentioned.

Further, it is more preferable to apply the heat treatment after imparting the above mechanical action.

In addition, it is particularly preferable to perform the heat treatment at a temperature of 700 캜 or higher after compounding with the carbon precursor after imparting the above-mentioned mechanical action.

[Specific Embodiment of Negative Electrode Active Material]

Specific examples of the negative electrode active material include, for example, (a) graphite particles composed of a composite and / or a mixture of nuclear graphite and carbon having a rhombohedral constant of 0% or more and 35% or less, (b) a composite of nuclear graphite and graphite (C) graphite particles having a rhombohedral percentage of 0% or more and 35% or less, and mixtures of (a) to (c), wherein the graphite particles have a rhombohedral constant of 0 to 35% have.

Here, examples of the nuclear graphite include natural graphite and artificial graphite described above. Natural graphite as nuclear graphite is preferably spherical natural graphite (in the present specification, spherical natural graphite is also referred to as spheroidized graphite).

For example, in the case of a mixture of (a) and (b), the ratio of the complex and / or mixture of (b) to the complex and / or mixture of (a) is usually at least 5 wt% It is preferably at least 10 wt%, more preferably at least 15 wt%. It is usually 95 wt% or less, preferably 90 wt% or less, and more preferably 85 wt% or less. (b) is too small, the irreversible capacity increases and the battery capacity tends to decrease. When the mixing ratio is too large, the Li water solubility at low temperatures tends to decrease.

the proportion of the graphite particles of (c) to the composite and / or mixture of (a) is usually not less than 5 wt%, preferably not less than 10 wt% , More preferably at least 15 wt%. It is usually 70 wt% or less, preferably 60 wt% or less, and more preferably 50 wt% or less. If the mixing ratio of (c) is too small, there is a fear that when the electrode is pressed at a high density in order to increase the battery capacity, the press load becomes high and it becomes difficult to increase the density. If too large, the irreversible capacity becomes large, .

(b) and (c), the proportion of the graphite particles of (c) to the composite and / or mixture of (b) is usually not less than 5 wt%, preferably not less than 10 wt% , More preferably not less than 20 wt%. It is usually 70 wt% or less, preferably 60 wt% or less, and more preferably 50 wt% or less. If the mixing ratio of (c) is too small, the density of the press increases when the electrode is pressed at a high density in order to increase the battery capacity. When the ratio is too large, the irreversible capacity increases and the battery capacity tends to decrease .

A combination of the combination of the composite of (a) and (b), the combination of the composite of (a) and the graphite particles of (c), and the combination of the composite of (b) and the graphite particles of (c) the combination of the composite of (a) and the composite of (b), the combination of the composite of (a) and the graphite particles of (c) is more preferable because it is easy to produce a high density electrode, .

The negative electrode according to the present invention may contain graphite particles whose rhombohedral percentages do not satisfy the above range. When the graphite particles are mixed with other graphite having a ratios of the ratios of 0% or more and 35% or less, the other graphite is usually added in an amount of 2 wt% or more, preferably 5 wt% or more, wt% or more, and more preferably 10 wt% or more. It is usually not more than 50 wt%, preferably not more than 45 wt%, more preferably not more than 40 wt%. If the amount of other graphite is too small, it tends to be difficult to obtain an effect of mixing other graphite, and if it is excessively large, the effect of the present invention tends to be small.

When the negative electrode active material contains (a) and / or (b), the rhombohedral ratio of the nuclear graphite composing these composites is usually 0% or more, preferably 3% or more, , More preferably not less than 5%, and usually not more than 35%, preferably not more than 27%, more preferably not more than 24%, particularly preferably not more than 20%. The rhombohedral percentages of the nuclear graphite composing these composites can be obtained by the same method as the above-mentioned graphite particles.

(a) graphite particles composed of a composite and / or a mixture of nuclear graphite and carbon having a rhombohedral constant of 0% or more and 35% or less

Graphite particles composed of a composite and / or a mixture of nuclear graphite and carbon having a rhombohedral constant of 0% or more and 35% or less can be obtained, for example, by coating or bonding a nuclear precursor to a nuclear graphite, Firing, or deposition by CVD (Chemical Vapor Deposition) method

.

The composite refers to graphite particles in which carbon is coated or bonded to nuclear graphite and the rhombohedral ratio is within the above range. The covering ratio of carbon is usually 1% by mass or more, preferably 2% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less.

The coating rate of the present invention can be calculated by using the following formula in terms of the amount of nuclear graphite and the carbon mass derived from the carbon precursor after firing.

Coverage (mass%) = carbon mass ÷ (nuclear graphite mass + carbon mass) × 100

The above-mentioned mixture means, for example, that graphite particles having a rhombohedral constant of 0% or more and 35% or less and carbon are mixed at an arbitrary ratio in a state of no coating or bonding.

(b) graphite particles having a rhombohedral constant of 0% or more and 35% or less, which is composed of a composite and / or a mixture of nuclear graphite and graphite

Graphite particles composed of a composite and / or mixture of nuclear graphite and graphite having a rhombohedral constant of 0% or more and 35% or less can be obtained, for example, by coating or bonding a nuclear graphite with a carbon precursor, At a temperature below the melting point of graphite.

The composite refers to graphite particles having graphite and / or non-graphite coated or bonded to nuclear graphite and having a rhombohedral constant of 0% or more and 35% or less.

The covering ratio of graphite is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less.

The coating rate referred to in the present invention can be calculated by using the following equation in terms of the amount of nuclear graphite and the graphite mass derived from the carbon precursor after graphitization.

Coating ratio (mass%) = graphite mass derived from precursor ÷ (nuclear graphite mass + graphite mass derived from precursor) × 100

The above-mentioned mixture means that graphite particles having a rhombohedral constant of 0% or more and 35% or less and graphite are mixed at an arbitrary ratio in a state free from coating or bonding.

(c) graphite particles having a rhombohedral ratio of 0% or more and 35% or less

The graphite particles having a rhombohedral constant of 0% or more and 35% or less are made up only of graphite particles having a rhombohedral constant of not less than 0% and not more than 35%, which do not contain the structures (a) and (b). Specifically, it refers to nuclear graphite subjected to kinetic energy treatment, and graphite particles not mixed with carbon and / or graphite or mixed therein. Also, graphite particles obtained by firing graphite particles having a rhombohedral constant of 0% or more and 35% or less at 400 ° C to 3200 ° C may be used.

The graphite particles may be composed of one kind or may be composed of a plurality of graphite particles having different shapes and particle diameters.

&Lt; Physical properties of carbonaceous materials &

When a carbonaceous material is used as the negative electrode active material, it is preferable to have the following physical properties.

(X-ray parameter)

The d-value (inter-layer distance) of the lattice plane (002 plane) obtained by X-ray diffraction of the carbonaceous material by the X-ray diffraction method is preferably 0.335 nm or more, and is usually 0.360 nm or less, preferably 0.350 nm or less, And more preferably 0.345 nm or less. In addition, the crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction by the scientific method is preferably 1.0 nm or more, more preferably 1.5 nm or more.

(Average particle diameter based on volume)

The volume-based average particle diameter of the carbonaceous material is an average particle diameter (median diameter) based on volume determined by a laser diffraction / scattering method, is usually 1 占 퐉 or more, preferably 3 占 퐉 or more, more preferably 5 占 퐉 or more , And particularly preferably not less than 7 mu m, and is usually not more than 100 mu m, preferably not more than 50 mu m, more preferably not more than 40 mu m, further preferably not more than 30 mu m, and particularly preferably not more than 25 mu m.

If the volume-based average particle diameter is less than the above-mentioned range, the irreversible capacity is increased and the initial battery capacity may be lost. On the other hand, if it exceeds the above-mentioned range, uneven patterns (coated surfaces) are likely to be produced when the electrode is produced by coating, which is not preferable in the battery manufacturing process.

The volume-based average particle diameter was measured by dispersing carbon powder in a 0.2 mass% aqueous solution (about 10 ml) of polyoxyethylene (20-mer) sorbitan monolaurate as a surfactant and measuring the particle diameter LA-700 manufactured by Sasa Corporation). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material.

(Raman R value, Raman half width)

The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectroscopy and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1.5 or less and 1.2 Or less, more preferably 1 or less, and particularly preferably 0.5 or less.

When the Raman R value is less than the above range, the crystallinity of the particle surface becomes excessively high, and as a result of charging and discharging, there is a case where the number of sites where Li enters between the layers is small. That is, the chargeability of water may be lowered. In addition, when the negative electrode is densified by applying it to the current collector after pressing it, the crystal tends to be oriented in the direction parallel to the electrode plate, resulting in a decrease in load characteristics. In particular, when the Raman R value is 0.1 or more, a preferable coating film is formed on the surface of the negative electrode, whereby the storage characteristics, cycle characteristics, and load characteristics can be improved.

On the other hand, if it exceeds the above-mentioned range, the crystallinity of the particle surface is lowered and the reactivity with the non-aqueous liquid electrolyte is increased, which may result in reduction of efficiency and increase of gas generation.

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

When the Raman half width is less than the above range, the crystallinity of the particle surface becomes excessively high, and the number of sites where Li enters between the layers may decrease with charge and discharge. That is, the chargeability of water may be lowered. In addition, when the negative electrode is densified by pressing after the application to the current collector, the crystal tends to be aligned in the direction parallel to the electrode plate, which may result in a decrease in load characteristics. On the other hand, if it exceeds the above-mentioned range, the crystallinity of the particle surface is lowered and the reactivity with the non-aqueous liquid electrolyte is increased, which may result in reduction of efficiency and increase of gas generation.

The Raman spectrum was measured by using a Raman spectrometer (Raman spectroscope from Nippon Shokubai Co., Ltd.), filling the sample by dropping it in the measurement cell, irradiating the sample surface with argon ion laser light, And rotating it in the plane of the surface. The intensity I _A of the peak P _{A in} the vicinity of 1580 cm ^-1 and the intensity I _B of the peak P _{B in} the vicinity of 1360 cm ^-1 were measured for the obtained Raman spectrum and the intensity ratio R (R = I _B / I _A ). And the Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention. The half width of the peak P _{A in} the vicinity of 1580 cm ^-1 of the obtained Raman spectrum is measured and defined as the Raman half width of the carbonaceous material.

The Raman measurement conditions are as follows.

· Argon ion laser wavelength: 514.5 nm

Laser power on sample: 15 to 25 mW

Resolution: 10-20 cm ^-1

Measuring range: 1100 cm ^-1 to 1730 cm ^-1

· Raman R value, Raman half width analysis: background processing

· Smoothing processing: simple average, convolution 5 points

(BET specific surface area)

BET specific surface area of the carbonaceous material is a value of a specific surface area measured using the BET method, generally not less than ^{0.1 ㎡ · g -1, 0.7 ㎡} · g -1 or more is preferable, 1.0 ㎡ · g ^-1 or more more preferably, 1.5 ㎡ · g ^-1 or more is particularly preferable, and further, and typically less than ^{100 ㎡ · g -1, 25 ㎡} · g -1 or less is preferable, and 15 ㎡ · g ^-1 or less, more And particularly preferably 10 m &lt; 2 &gt; g &lt; ^-1 &gt; or less.

If the value of the BET specific surface area is less than this range, the water solubility of lithium tends to deteriorate at the time of charging when used as a negative electrode material, and lithium tends to precipitate from the surface of the electrode, which may lower the stability. On the other hand, if it exceeds this range, reactivity with the nonaqueous electrolyte solution increases when used as a negative electrode material, and gas generation tends to be increased, which makes it difficult to obtain a preferable battery.

The specific surface area was measured by the BET method using a surface area meter (a fully automatic surface area measuring apparatus manufactured by Okura Riken). The sample was subjected to preliminary drying at 350 DEG C for 15 minutes under flowing nitrogen gas, Of the nitrogen helium mixed gas precisely adjusted so that the value of the nitrogen adsorption BET 1 point method is obtained by the gas flow method. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material.

(Circularity)

When the circularity is measured as a spherical degree of the carbonaceous material, it is preferable to fall within the following range. The circularity is defined as &quot; circularity = (peripheral length of substantial circle having the same area as the particle projection shape) / (actual peripheral length of the particle projection shape) &quot;, and when the circularity is 1, do.

The circularity of the carbonaceous material having a particle diameter in the range of 3 to 40 mu m is preferably as close to 1 as possible, more preferably 0.1 or more, particularly preferably 0.5 or more, more preferably 0.8 or more, and 0.85 Or more, more preferably 0.9 or more. High current density charging and discharging characteristics are improved as the circularity is increased. Therefore, when the degree of circularity is less than the above-mentioned range, the filling property of the negative electrode active material is lowered, the resistance between the particles is increased, and the short-time high-current density charge / discharge characteristics are lowered.

The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of the sample was dispersed in a 0.2 mass% aqueous solution (about 50 ml) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, irradiated with ultrasound of 28 kHz at an output of 60 W for 1 minute, 0.6 to 400 mu m, and the particle diameter is in the range of 3 to 40 mu m. The circularity obtained by the measurement is defined as a circular shape of the carbonaceous material.

The method for improving the circularity is not particularly limited, but it is preferable that spheres are formed by sphering to form the shape of the interstitial spaces when the electrode bodies are formed. Examples of the sphering treatment include a method of mechanically approaching a spherical shape by applying a shearing force and a compressive force, a mechanical and physical treatment method of granulating a plurality of fine particles by a binder or an adhesive force of the particles themselves have.

(Tap density)

The tap density of the carbonaceous material is usually 0.1 g · cm ^-3 or more, preferably 0.5 g · cm ^-3 or more, more preferably 0.7 g · cm ^-3 or more, and particularly preferably 1 g · cm ^-3 or more And is preferably 2 g · cm ^-3 or less, more preferably 1.8 g · cm ^-3 or less, and particularly preferably 1.6 g · cm ^-3 or less. When the tap density is below the above range, the charging density does not become high when used as the negative electrode, and a high capacity battery may not be obtained. On the other hand, if it exceeds the above range, voids between particles in the electrode become too small, conductivity between particles is not ensured, and it is difficult to obtain favorable battery characteristics.

The tap density was measured by passing a sieve having a pitch of 300 탆 through a sieve and dropping the sample into a 20 cm 3 tapping cell to fill the sample up to the top surface of the cell. Thereafter, a powder density meter (for example, Denser), 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. And the tap density calculated by the measurement is defined as the tap density of the carbonaceous material.

(Orientation ratio)

The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. If the orientation ratio is less than the above range, the high-density charge-discharge characteristics may be deteriorated. The upper limit of the above range is the theoretical upper limit of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. 0.47 g of the sample was charged into a molding machine having a diameter of 17 mm and compressed to 58.8 MN · m ^-2 , and the formed body was set to be flush with the surface of the sample holder for measurement using clay, and X-ray diffraction was measured. From the peak intensity of (110) diffraction and (004) diffraction of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. And the orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material.

The X-ray diffraction measurement conditions are as follows. Further, &quot; 2 &amp;thetas; &quot; indicates a diffraction angle.

· Target: Cu (Kα line) graphite monochrometer

Slit:

  Divergence slit = 0.5 degree

  Receiving slit = 0.15 mm

  Scattering slit = 0.5 degree

· Measuring range and step angle / measuring time:

  (110) plane: 75 degrees? 2?? 80 degrees    1 degree / 60 seconds

  (004) plane: 52 degrees? 2?? 57 degrees    1 degree / 60 seconds

(Aspect ratio (powder))

The aspect ratio of the carbonaceous material is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 5 or less. If the aspect ratio exceeds the above range, streaks may occur at the time of polar plate printing, a uniform coated surface may not be obtained, and the high current density charge / discharge characteristics may be deteriorated. The lower limit of the above range is the theoretical lower limit of the aspect ratio of the carbonaceous material.

The aspect ratio is measured by observing the particles of the carbonaceous material with a scanning electron microscope. When 50 arbitrary graphite particles fixed on the end face of a metal having a thickness of 50 占 퐉 or less are selected and the stage on which the sample is immobilized is rotated and inclined three dimensionally, And the diameter A which is the shortest perpendicular to the diameter A is measured to obtain the average value of A / B. The aspect ratio (A / B) determined by the measurement is defined as the aspect ratio of the carbonaceous material.

&Lt; Configuration of negative electrode and manufacturing method >

Any known method may be used for the production of the electrode so long as the effect of the present invention is not significantly impaired. For example, the negative electrode active material can be formed by adding a binder, a solvent, and if necessary, a thickener, a conductive material, a filler or the like to form a slurry, applying the slurry to a current collector, followed by drying and pressing.

(Whole house)

As the current collector for holding the negative electrode active material, any known one may be used. As the collector of the negative electrode, for example, a metal material such as aluminum, copper, nickel, stainless steel, or nickel-plated steel can be used, but copper is particularly preferable from the viewpoints of ease of processing and cost.

When the current collector is made of a metal material, examples of the current collector include a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal and a foamed metal. Among them, preferably a metal thin film, more preferably a copper foil, more preferably a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method, both of which can be used as current collectors.

The thickness of the current collector is usually not less than 1 占 퐉, preferably not less than 5 占 퐉, and usually not more than 100 占 퐉, preferably not more than 50 占 퐉. If the thickness of the negative electrode current collector is excessively large, the capacity of the whole battery may be excessively reduced. On the other hand, if the thickness is excessively thin, handling may become difficult.

(The ratio of the thickness of the current collector to the thickness of the negative electrode active material layer)

The ratio of the thickness of the collector to the thickness of the negative electrode active material layer is not particularly limited, but the value of &quot; (thickness of the negative electrode active material layer on one side immediately before pouring the nonaqueous electrolyte solution) / More preferably 10 or less, particularly preferably 0.1 or more, more preferably 0.4 or more, and particularly preferably 1 or more. If the ratio of the thickness of the collector to the thickness of the negative electrode active material layer exceeds the above range, the current collector may generate heat due to the short circuit at the time of high current density charge / discharge. Below the above range, the volume ratio of the current collector to the negative electrode active material may increase, and the capacity of the battery may decrease.

(Binder)

The binder binding the negative electrode active material is not particularly limited as long as it is a stable material for a non-aqueous liquid electrolyte or a solvent used in the production of an electrode.

Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; Rubber-like polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, NBR (acrylonitrile-butadiene rubber) and ethylene-propylene rubber; Styrene-butadiene-styrene block copolymer or hydrogenated product thereof; Thermoplastic elastomeric polymers such as EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer or hydrogenated product thereof; Soft dendritic polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer and propylene -olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymer; And polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions). These may be used singly or in combination of two or more in any combination.

The ratio of the binder to the negative electrode active material is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, particularly preferably 0.6 mass% or more, further preferably 20 mass% or less, and 15 mass% , More preferably 10 mass% or less, and particularly preferably 8 mass% or less. If the ratio of the binder to the negative electrode active material exceeds the above range, the binder ratio in which the amount of the binder does not contribute to the battery capacity is increased, and the battery capacity may be lowered in some cases. Below the above range, the strength of the negative electrode may be lowered.

In particular, when a rubber-like polymer represented by SBR is contained in the main component, the ratio of the binder to the negative electrode active material is usually 0.1 mass% or more, preferably 0.5 mass% or more, more preferably 0.6 mass% or more And is usually not more than 5 mass%, preferably not more than 3 mass%, more preferably not more than 2 mass%. When a fluorine-based polymer typified by polyvinylidene fluoride is contained as a main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, , And usually 15 mass% or less, preferably 10 mass% or less, and more preferably 8 mass% or less.

(Slurry forming solvent)

The solvent for forming the slurry is not 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 to be used as needed. The solvent is not limited to the aqueous solvent or the organic solvent May be used.

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

Particularly, in the case of using an aqueous solvent, it is preferable to add a dispersant or the like in addition to the thickener, and to make the slurry using a latex such as SBR. These solvents may be used alone or in combination of two or more in any combination.

(Thickener)

The thickener is typically used to prepare the viscosity of the slurry. Specific examples of the thickening agent include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, starch starch, phosphorylated starch, casein, and salts thereof. These may be used singly or in combination of two or more in any combination.

When a thickener is used, the ratio of the thickener to the negative electrode active material is usually not less than 0.1% by mass, preferably not less than 0.5% by mass, more preferably not less than 0.6% by mass, and usually not more than 5% , Preferably 3 mass% or less, and more preferably 2 mass% or less. When the ratio of the thickener to the negative electrode active material is less than the above range, the coating property may remarkably decrease. On the other hand, if the ratio exceeds the above range, the ratio of the negative electrode active material in the negative electrode active material layer is lowered, and the capacity of the battery is lowered and the resistance between the negative electrode active material is increased.

(Electrode density)

The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the 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 , Particularly preferably 1.3 g · cm ^-3 or higher, more preferably 2.2 g · cm ^-3 or lower, still more preferably 2.1 g · cm ^-3 or lower, still more preferably 2.0 g · cm ^-3 or lower, And particularly preferably 1.9 g · cm ^-3 or less. If the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed and the high irreversible capacity increases due to the increase of the initial irreversible capacity and the decrease in the permeability of the nonaqueous electrolyte solution near the interface between the current collector and the negative electrode active material Density charging and discharging characteristics may be deteriorated. Below the above range, the conductivity between the negative electrode active materials is lowered, the battery resistance is increased, and the capacity per unit capacity is sometimes lowered.

(Thickness of the negative electrode plate)

Thickness of the negative electrode plate is designed in accordance with the positive electrode plate to be used and is not particularly limited, but the thickness of the laminated material layer excluding the thickness of the metal foil of the core material is usually 15 占 퐉 or more, preferably 20 占 퐉 or more, more preferably 30 占 퐉 Or more, and usually 300 μm or less, preferably 280 μm or less, and more preferably 250 μm or less.

(Surface coating of negative electrode)

A material having a composition different from that of the negative electrode plate may be used on the surface of the negative electrode plate. Examples of surface adhesion materials include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide and bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, Sulfates such as aluminum sulfate, and carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate, and the like.

4. Separator

In the non-aqueous liquid electrolyte secondary battery of the present invention, a separator is interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the non-aqueous liquid electrolyte of the present invention is usually impregnated with this separator.

The material and shape of the separator are not particularly limited, and any known material may be employed as long as the effect of the present invention is not significantly impaired. Among them, in the present invention, polyolefin-based resins formed of a stable material for the non-aqueous liquid electrolyte of the present invention, other resins, glass fibers, and inorganic materials can be used as constituent components. As the shape, it is preferable to use a porous sheet or a nonwoven fabric-like shape excellent in liquid retention.

The separator used in the present invention preferably has a polyolefin-based resin as a part of its constituent components. Specific examples of the polyolefin resin include polyethylene resins, polypropylene resins, 1-polymethylpentene, polyphenylene sulfide, and the like.

Examples of the polyethylene-based resin include low density polyethylene, linear low density polyethylene, linear ultra low density polyethylene, medium density polyethylene, high density polyethylene and copolymers based on ethylene, namely, ethylene and propylene, butene-1, 1, heptene-1, octene-1, and the like; Vinyl esters such as vinyl acetate and vinyl propionate; Unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate, and unsaturated compounds such as conjugated dienes and nonconjugated dienes, or copolymers of one or more comonomers A copolymer or a mixed composition thereof. The content of the ethylene unit in the ethylene polymer is usually more than 50% by mass.

Among these polyethylene-based resins, at least one kind of polyethylene-based resin selected from low-density polyethylene, linear low-density polyethylene and high-density polyethylene is preferable, and high-density polyethylene is most preferable.

The polymerization catalyst of the polyethylene-based resin is not particularly limited, and may be any of a chisel type catalyst, a Phillips type catalyst, a Kaminsky type catalyst and the like. As the polymerization method of the polyethylene-based resin, there are one-step polymerization, two-step polymerization, and multi-stage polymerization or the like, and any method of the polyethylene-based resin can be used.

The melt flow rate (MFR) of the polyethylene-based resin is not particularly limited, but MFR is preferably 0.03 to 15 g / 10 min, more preferably 0.3 to 10 g / 10 min. When the MFR is within the above range, the back pressure of the extruder does not become excessively high at the time of molding, and the productivity is excellent. The MFR in the present invention refers to a measured value under the conditions of a temperature of 190 占 폚 and a load of 2.16 kg in accordance with JIS K7210.

The production method of the polyethylene-based resin is not particularly limited, and a known polymerization method using a known olefin polymerization catalyst, for example, a multisite catalyst typified by a chitler / natta catalyst, and a metallocene catalyst represented by a metallocene catalyst And a polymerization method using a single site catalyst.

Next, examples of the polypropylene resin will be described. Examples of the polypropylene-based resin in the present invention include homopolypropylene (propylene homopolymer), or copolymers of propylene with at least one of ethylene, 1-butene, 1-pentene, 1-hexene, And random copolymers or block copolymers with alpha -olefins such as 1-decene. Of these, homopolypropylene is more preferably used from the viewpoint of mechanical strength when it is used in a battery separator.

The polypropylene resin preferably has an isotactic pentad fraction of from 80 to 99%, more preferably from 83 to 98%, and still more preferably from 85 to 97%, which exhibits stereoregularity do. If the isotactic pentad fraction is too low, the mechanical strength of the battery separator may be lowered. On the other hand, the upper limit of the isotactic pentad fraction is defined as an upper limit value obtained industrially at present, but the present invention is not limited to this case when a resin having higher regularity at an industrial level is developed in the future.

The term "isotactic pentad fraction" means a stereostructure in which all five methyl groups which are side chains are positioned in the same direction or a ratio thereof to the main chain by a carbon-carbon bond constituted by any five consecutive propylene units . The attribution of the signal of the methyl group region is described in A. Zambellietatal. (Macromol. 8, 687 (1975)).

It is preferable that the polypropylene resin has a Mw / Mn of 1.5 to 10.0, which is a parameter indicating a molecular weight distribution. More preferably 2.0 to 8.0, and still more preferably 2.0 to 6.0. When Mw / Mn is smaller, it means that the molecular weight distribution is narrower. However, when Mw / Mn is less than 1.5, there are problems such as deterioration of extrusion moldability and the like. On the other hand, when Mw / Mn exceeds 10.0, the number of low-molecular-weight components increases, and the mechanical strength of the resultant separator for a battery tends to be lowered. Mw / Mn is obtained by GPC (Gel Permeation Chromatography).

The melt flow rate (MFR) of the polypropylene resin is not particularly limited, but MFR is preferably 0.1 to 15 g / 10 min, more preferably 0.5 to 10 g / 10 min. When the MFR is less than 0.1 g / 10 min, the melt viscosity of the resin at the time of molding processing is high and productivity is lowered. On the other hand, if it exceeds 15 g / 10 min, practical problems such as insufficient strength of the resulting battery separator tends to occur. The MFR was measured under conditions of a temperature of 230 占 폚 and a load of 2.16 kg in accordance with JIS K7210.

As other materials for the resin and the glass fiber separator, for example, aromatic polyamide, polytetrafluoroethylene, polyether sulfone, glass filter and the like can be used in combination with the polyolefin resin. These materials may be used alone or in combination of two or more in any combination.

The thickness of the separator is arbitrary, but is usually 1 mu m or more, preferably 5 mu m or more, more preferably 8 mu m or more, and usually 50 mu m or less, preferably 40 mu m or less, desirable. If the separator is thinner than the above range, the insulating property and the mechanical strength may be lowered. In addition, if the thickness is excessively larger than the above range, the battery performance such as rate characteristics may be deteriorated, and the energy density of the non-aqueous liquid electrolyte secondary battery as a whole may be lowered.

When a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more And is usually not more than 90%, preferably not more than 85%, more preferably not more than 75%. If the porosity is excessively smaller than the above range, the film resistance tends to increase and the rate characteristic to deteriorate. On the other hand, if it is larger than the above range, the mechanical strength of the separator is lowered and the insulating property tends to be lowered.

The average pore diameter of the separator is arbitrary, but is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore diameter exceeds the above range, a short circuit easily occurs. Below the above range, the film resistance may increase and the rate characteristic may decrease.

On the other hand, as a material of the inorganic material, for example, an oxide such as alumina or silicon dioxide, a nitride such as aluminum nitride or silicon nitride, or a sulfate such as barium sulfate or calcium sulfate is used, and a particle shape or a fiber shape is used.

In the form of a thin film, nonwoven fabric, woven fabric, microporous film or the like is used. In the case of the thin film shape, it is preferable that the pore diameter is 0.01 to 1 mu m and the thickness is 5 to 50 mu m. In addition to the above independent thin film form, a separator formed by using a binder made of a resin and forming a composite porous layer containing particles of the inorganic substance on the surface layer of the positive electrode and / or the negative electrode may be used. For example, alumina particles having a 90% particle diameter of less than 1 占 퐉 are formed on both surfaces of a positive electrode by using a fluororesin as a binder to form a porous layer.

5. Battery Design

<Electrode Group>

The electrode group includes a laminated structure in which the above-mentioned positive electrode plate and negative electrode plate are interposed between the above separators, and a structure in which the positive electrode plate and the negative electrode plate are wound in a vortex shape via the above separator Or the like. The ratio of the volume of the electrode group in the internal volume of the electrode (hereinafter referred to as the electrode group occupancy rate) is usually 40% or more, preferably 50% or more, and usually 90% % Or less.

If the occupancy rate of the electrode group is less than the above range, the battery capacity becomes small. When the amount is larger than the above range, the pore space is small and the battery is heated to a high temperature, the member expands, the vapor pressure of the liquid component of the electrolyte increases, and the internal pressure rises. As a result, Or the gas discharge valve for discharging the internal pressure to the outside may be operated.

<Current collecting structure>

Although the current collecting structure is not particularly limited, it is preferable that the resistance of the wiring portion and the bonding portion is reduced in order to realize the improvement of the charging / discharging characteristics of the high current density by the non-aqueous liquid electrolyte of the present invention more effectively. When the internal resistance is reduced in this manner, the effect of using the non-aqueous liquid electrolyte of the present invention is particularly excellently demonstrated.

In the case where the electrode group is the above-described laminated structure, a structure in which the metal core portions of the respective electrode layers are bundled and welded to the terminals is preferably used. When the electrode area of one sheet becomes large, the internal resistance becomes large. Therefore, it is preferable to form a plurality of terminals in the electrode to reduce the resistance. In the case where the electrode group is the winding structure described above, a plurality of lead structures are formed on the positive electrode and the negative electrode, respectively, and are bundled with the terminals, so that the internal resistance can be reduced.

<External case>

The material of the case is not particularly limited as long as it is a stable material for the non-aqueous liquid electrolyte used. Specifically, a nickel-plated steel sheet, a metal such as stainless steel, aluminum or an aluminum alloy or a magnesium alloy, or a laminated film of a resin and an aluminum foil (laminate film) is used. From the viewpoint of weight reduction, a metal or laminate film of aluminum or an aluminum alloy is preferably used.

In an outer case using a metal, the metals are welded to each other by laser welding, resistance welding, or ultrasonic welding to form a sealed structure. Alternatively, the metal case may be made of a caulking structure using the resin gasket. &Lt; / RTI &gt; In the case of the outer case using the above laminate film, the resin sealing layers are thermally fused to each other to form a sealed structure. A resin different from the resin used for the laminate film may be interposed between the resin layers in order to increase the sealing property. Particularly, when the resin layer is thermally fused to form a sealed structure through the current collecting terminal, a resin having a polar group or a modified resin having a polar group introduced thereinto is preferably used as the interposed resin, because the resin is bonded to the metal.

<Protection Device>

As a protection device, a PTC (Positive Temperature Coefficient) which increases resistance when abnormal heat or excessive current flows, a thermal fuse, a thermistor, and a current flowing in the circuit due to a sudden rise in internal pressure or internal temperature during abnormal heat generation A valve (current shut-off valve) or the like can be used. It is preferable to select the protection device under a condition that it does not operate under normal use of a high current, and it is more preferable that the protection device does not cause abnormal heat generation or thermal runaway without a protection device.

<Exterior>

The non-aqueous liquid electrolyte secondary battery of the present invention is usually constructed by housing the non-aqueous liquid electrolyte, the negative electrode, the positive electrode, the separator, and the like in an external body. The external body is not particularly limited, and any known body can be employed as long as the effect of the present invention is not significantly impaired. Specifically, the material of the outer body is arbitrary, but usually, for example, iron, stainless steel, aluminum or an alloy thereof, nickel, titanium or the like which is plated with nickel is used.

The shape of the external body is also arbitrary, and may be, for example, a cylindrical shape, a square shape, a laminate shape, a coin shape, or a large shape.

6. Battery Performance

The non-aqueous liquid electrolyte secondary battery of the present invention can be used without particular limitation, but preferably it can be used for a high-voltage battery or a high-capacity battery.

In the case of, for example, a lithium ion secondary battery, the higher voltage is usually 4.3 V or higher, preferably 4.4 V or higher, more preferably 4.5 V or higher, and still more preferably 4.6 V or higher.

The higher capacity is, for example, in the case of a 18650 type battery, usually 2600 mAh or higher, preferably 2800 mAh or higher, and more preferably 3000 mAh or higher.

Example

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.

[Preparation of electrolytic solution]

(EC) or propylene carbonate (PC) as the cyclic carbonate represented by the general formula (1), 4-fluoroethylene carbonate (MFEC) as the fluorinated cyclic carbonate represented by the general formula (2) (2,2,2-trifluoroethyl) methyl carbonate (TFEMC) is used as the fluorinated chain type carbonate represented by the general formula (3), and ethyl methyl carbonate (DFEC) is used as the other solvent, (DMC), hexamethylene diisocyanate (HMDI), 1,3-bis (isocyanatomethyl) cyclohexane (BIMCH), 1,3,5-tris (6-isocyanato 3H, 5H) -thione (CTI), FSO ₃ Li, LiBF ₄ , or LiPO ₂ F ₂ in the ratio shown in Table 1 . The thus dried LiPF ₆ was dissolved in a proportion of 1 mol / l to prepare a basic electrolyte solution 1 to 28.

[Salt Solubility Evaluation]

The prepared basic electrolytic solution 1 to 28 was cooled, and the presence or absence of salt precipitation was visually confirmed at 0 ° C. The electrolytic solution in which precipitation did not occur was evaluated as?, And the electrolytic solution in which precipitation occurred was evaluated as X. The results are summarized in Table 2.

The deposition of only 21,000 electrolytic solutions consisting of only cyclic carbonate and fluorinated chain carbonate was observed. It was found that it is necessary to coexist the fluorinated cyclic carbonate in the mixed electrolyte of the non-fluorinated cyclic carbonate and the fluorinated chain carbonate in that this precipitate is dissolved in the electrolytic solution by mixing the fluorinated cyclic carbonate.

[Example A: High-voltage battery having an open-circuit voltage of 4.90 V between battery terminals]

[Selection of electrolytic solution]

Basic electrolytes 1 to 19, 24 and 25 in which salt precipitation was not observed at 0 ° C were used as the electrolytes used in Examples 1 to 21 and the basic electrolytes 20, 22 and 26 were used as electrolytes used in Comparative Examples 1 to 3 .

[Production of negative electrode]

100 parts by mass of aqueous dispersion of carboxymethylcellulose sodium (concentration of carboxymethylcellulose sodium of 1% by mass) as 98 parts by mass of natural graphitizing carbonaceous material (ratios of ratios of 25%) and styrene-butadiene rubber (Concentration of styrene-butadiene rubber: 50% by mass) was added to the mixture, followed by mixing with a disperser to prepare a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 占 퐉, dried, and rolled by a press machine, cut into a shape having a width of 30 mm, a length of 40 mm, a width of 5 mm and a length of 9 mm as a size of the active material layer, Were used as negative electrodes for Examples 1 to 21 and Comparative Examples 1 to 3, respectively.

[Production of positive electrode]

85% by mass of LiNi _0.5 Mn _1.5 O ₄ as a positive electrode active material, 10% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in an N-methylpyrrolidone solvent, . The obtained slurry was applied to an aluminum foil having a thickness of 15 占 퐉, dried, and rolled by a press machine to cut into a shape having a width of 30 mm, a length of 40 mm, a width of 5 mm and a length of 9 mm as the size of the active material layer , And used as positive electrodes for Examples 1 to 21 and Comparative Examples 1 to 3, respectively.

[Production of lithium secondary battery]

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. The battery element was inserted into a bag made of a laminated film in which both surfaces of aluminum (thickness: 40 mu m) were covered with a resin layer while protruding and forming terminals of a positive electrode and a negative electrode. Then, the basic electrolytic solution described in Tables 3, And vacuum encapsulation was carried out to prepare a sheet-like battery, which was used as a battery used in Examples 1 to 21 and Comparative Examples 1 to 3, respectively.

[Practice driving]

The prepared sheet-shaped lithium secondary battery was sandwiched between glass plates to improve the adhesion between the electrodes, and the positive electrode potential at a constant current corresponding to 0.1 C at 25 캜 was set to 4.95 V on the basis of Li / Li ⁺ The exercise operation was carried out so that the voltage became 4.90 V. Here, 1 C represents the current value for discharging the reference capacity of the battery for 1 hour, 2 C represents the current value twice, and 0.1 C represents 1/10 the current value. The battery was charged at a constant current of 1/3 C in a range of 2.5 to 4.9 V at the battery terminal open-circuit voltage of 25 캜, and discharged at a constant current of 1/3 C, Respectively. With the above process, the practice operation of checking discharge capacity was performed.

[Evaluation of cycle characteristics]

Charging and discharging is carried out at a constant current of 1/3 C at a constant temperature of 60 ° C and a battery open-circuit voltage of 3.0 to 4.9 V, and then charged and discharged at a constant current of 2 C Was carried out for 200 cycles. During this period, charging and discharging were carried out at a constant current of 1/3 C at the 50th, 100th, and 200th cycles to confirm the capacity. The discharge capacity retention rate (cycle retention rate) was calculated from the equation (discharge capacity at the 200th cycle) / (discharge capacity at the first cycle) × 100 in the charge / discharge with a constant current of 1/3 C × 100. Also, the amount of generated gas and the resistance of the battery in which the practice operation was completed were measured. The evaluation results are shown in Tables 3, 4 and 5.

It can be seen from Table 3 that the non-aqueous liquid electrolytes (Examples 1 to 13) containing EC or the mixed cyclic carbonate of EC and PC in an amount greater than 15% by volume of the present invention (Examples 1 to 13) (Comparative Examples 1 and 2), it is found that the cycle retention ratio under the high voltage is excellent.

In Comparative Example 1 containing no cyclic carbonate represented by the general formula (1), the cycle retention rate was significantly lowered before carrying out the charge / discharge of 200 cycles, and the charge / discharge was impossible at the time of 200 cycles Represents the retention rate at 100 cycles). In addition, in Comparative Example 1, which does not contain the cyclic carbonate represented by the general formula (1), it was suggested that the initial amount of the generated gas was very large and the stability under high voltage was insufficient. In Comparative Example 2 containing 15% by volume of the cyclic carbonate represented by the general formula (1), the initial amount of generated gas was reduced and charge / discharge was possible even after 200 cycles. However, since the capacity retention rate was 32%, the stability under high voltage was insufficient . On the other hand, in Examples 1 to 13 containing more than 15% by volume of the cyclic carbonate represented by the general formula (1), gas generation was suppressed and the cycle retention rate was also improved. It is remarkable that EC and PC, which have lower resistance to oxidation in comparison with a fluorinated solvent, coexist in a certain amount in an electrolytic solution under a high voltage condition, thereby suppressing gas generation during endurance and improving cycle characteristics. This result suggests the specificity of EC and PC in the high voltmeter.

Further, when HMDI, CTI, FSO ₃ Li, LiBF ₄ , LiPO ₂ F ₂ , BIMCH, or a combination thereof was added as an auxiliary agent, the cycle retention ratio was more excellent (Examples 5 to 11). This effect is presumed to be due to the protective effect of the electrode surface by various auxiliaries, though not particularly limited.

It can also be seen from Table 4 that even in the composition containing more cyclic carbonate represented by the general formula (1), it shows a good cycle retention rate. Instead of increasing the proportion of the cyclic carbonate represented by the general formula (1), the ratio of the fluorinated chain carbonate is reduced. However, the fluorinated chain carbonate was satisfactorily worked even when it was reduced to 10% by volume.

When BIMCH and LiBF ₄ were added as an auxiliary agent to the electrolytic solution having a composition containing a large amount of the cyclic carbonate represented by the general formula (1), the cyclic retention ratio was even better. (Examples 17, 18, 19). This effect is presumed to be due to the protective effect of the electrode surface by the BIMCH, though not particularly limited.

Even when DFEC was used as the fluorinated cyclic carbonate, the cycle retention ratio was further improved by mixing the cyclic carbonate EC of the present invention, which is the same as MFEC (Examples 20 and 21). It is also possible to suppress the amount of generated gas by adding EC. That is, from the viewpoint of the effect of EC addition regardless of the kind of the fluorinated cyclic carbonate, from the viewpoints of inhibition of gas generation at the time of durability and improvement of cycle characteristics in the high voltage battery system, The cyclic carbonate represented by the formula (I) exhibits a specific and effective effect.

[Example B: Upper limit operation potential dependency]

[Production of lithium secondary battery]

A lithium secondary battery was produced in the same manner as in Example A, using the same negative electrode and positive electrode as in Example A.

[Practice driving]

To prepare a sheet-shaped lithium secondary battery, the positive electrode potential was set to 4.95 V, 4.90 V, and 4.85 V in terms of Li / Li ^{+ at} a constant current corresponding to 0.1 C at 25 캜 in a state sandwiched between the glass plates to improve the adhesion between the electrodes. , 4.75 V, 4.65 V, that is, 4.45 V, 4.85 V, 4.80 V, 4.70 V and 4.60 V, respectively. The battery was charged at a constant current of 1/3 C in the range of the open-circuit voltage between the battery terminals at 25 ° C, and then discharged at a constant current of 1/3 C, for four cycles. With the above process, the practice operation of checking discharge capacity was performed. Table 6 shows the discharging current capacities of each sheet-shaped lithium secondary battery after the practice operation at the time of 25 ° C and 1/3 C constant current discharge.

Even when the upper limit operating potential was in the range of the high positive electrode potential of 4.75 - 4.95 V, there was no significant difference in the discharge capacity after the practice operation, but the discharge capacity at 4.65 V was almost halved. This is because, if the upper limit operating potential is too low, the capacity can not be obtained because it can not be charged to a sufficient depth. Thus, the durability evaluation of Example B was carried out in the range of the upper limit operating potential of 4.75 V or more, at which a large discharge capacity could be extracted.

[Example B: cycle durability evaluation]

[Selection of electrolytic solution]

The basic electrolyte solution 3 in which salt precipitation was not observed at 0 DEG C was used as the electrolytic solution used in Examples 22 to 24, the basic electrolyte solution 7 was used as the electrolytic solution used in Examples 25 and 26, and the basic electrolytic solution 27 was used in Comparative Example 4 .

[Example 22]

[Production of negative electrode]

The negative electrode used in Example A was prepared in the same manner as the negative electrode used in Example A, and used as the negative electrode used in Example 22.

[Production of positive electrode]

Was prepared in the same manner as the positive electrode used in Example A, and used as the positive electrode used in Example 22.

[Production of lithium secondary battery]

Regarding the production of a lithium secondary battery, a lithium secondary battery was produced using the same electrolyte solution 3 as in Example A using the electrolyte solution 3 described in Table 1 as a basic electrolyte solution.

[Practice driving]

The positive electrode potential at a constant current corresponding to 0.1 C at 25 캜 was set to 4.75 V, that is, the open-circuit voltage between the battery terminals was set to 4.70 V in a state of being sandwiched between the glass plates in order to improve the adhesion between the electrodes. Exercise operation was carried out. The battery was charged at a constant current of 1/3 C at a temperature of 25 DEG C, 3.0 to 4.70 V as battery open-circuit voltage, and discharged at a constant current of 1/3 C, . With the above-described process, the exercise operation of the twenty-second embodiment was performed.

[Evaluation of cycle characteristics]

The battery in which the exercise operation is completed is charged and discharged at a constant current of 1/3 C in the range of 3.0 to 4.70 V as the battery open-circuit voltage at 60 캜 and then charged and discharged at a constant current of 2 C Was carried out for 200 cycles. During this period, charging and discharging were carried out at a constant current of 1/3 C at the 50th, 100th, and 200th cycles to confirm the capacity. The discharge capacity retention rate (cycle retention rate) was determined from the equation (discharge capacity at the 200th cycle) / (discharge capacity at the first cycle) × 100 in the charge / discharge cycle at a constant current of 1/3 C to obtain the evaluation result of Example 22 Respectively. The evaluation results are shown in Table 7.

[Example 23]

Practice operation and evaluation of the cycle characteristics were conducted in the same manner as in Example 22 except that the positive electrode upper limit potential was 4.85 V, that is, the battery open-circuit voltage was 4.80 V. Respectively. The evaluation results are shown in Table 7.

[Example 24]

The exercise operation and evaluation of the cycle characteristics were carried out in the same manner as in Example 22 except that the positive electrode upper limit potential was set to 4.90 V, that is, the battery open-circuit voltage was set to 4.85 V Respectively. The evaluation results are shown in Table 7.

[Example 25]

Regarding the production of the lithium secondary battery, the preparation was performed in the same manner as in Example 23, except that the electrolyte solution 7 described in Table 1 was used as the basic electrolyte solution, and the practice operation and the cycle characteristics were evaluated. The evaluation results are shown in Table 7.

[Example 26]

Regarding the production of a lithium secondary battery, an electrolytic solution 7 described in Table 1 was used as a basic electrolytic solution. The evaluation results are shown in Table 7.

[Comparative Example 4]

Regarding the production of the lithium secondary battery, the preparation, the exercise operation, and the cycle characteristics were evaluated using the same method as in Example 22, except that the electrolyte solution 27 described in Table 1 was used as the basic electrolyte solution. The evaluation results are shown in Table 7. Table 7 also shows Example 7 in which the positive electrode upper limit potential is 4.95 V.

It can be seen that a high cycle maintenance rate is exhibited in the high voltage design cells (Examples 22, 23 and 24) in which the positive electrode upper limit potentials are set to 4.75 V, 4.85 V, and 4.90 V, respectively.

For example, in Example 22 in which the positive electrode upper limit potential was set to 4.75 V by using the non-aqueous liquid electrolyte according to the present invention, the capacity retention ratio after 200 cycles was as high as 82.0%. By applying this design, high durability When the non-aqueous liquid electrolyte containing no fluorinated solvent according to the present invention is used in the cycle test at the same positive upper limit potential, the capacity retention rate is greatly reduced to 55.7% (Comparative Example 4 ). Even in such a high-voltage design cell in which the open-circuit voltage between battery terminals exceeds 4.7 V, a lithium secondary battery having high durability can be obtained by using the non-aqueous liquid electrolyte according to the present invention.

Further, when CTI was added as an auxiliary agent, a better cycle retention ratio was shown (Examples 25, 26 and 7). This effect is presumed to be due to the protective effect of the electrode surface by CTI although not particularly limited.

[Example C]

[Selection of electrolytic solution]

The basic electrolytic solution 2 and the basic electrolytic solution 28 in which salt precipitation was not observed at 0 캜 were used as the electrolytic solutions used in Example 27 and Comparative Example 5, respectively.

[Production of negative electrode]

The negative electrode used in Examples 27 and Comparative Example 5 was prepared in the same manner as the negative electrode used in Examples A and B.

[Production of positive electrode]

85% by mass of Li _1.1 (Ni _0.45 Mn _0.45 Co _0.10 ) O ₂ as a positive electrode active material, 10% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride as a binder were dissolved in an N-methylpyrrolidone solvent Mixed and slurried. The obtained slurry was coated on an aluminum foil having a thickness of 15 占 퐉 coated with a conductive auxiliary agent in advance and then rolled by a press machine to obtain an active material layer having a width of 30 mm and a length of 40 mm and a width of 5 mm and a length of 9 mm To prepare a positive electrode for use in Example 27 and Comparative Example 5.

[Production of lithium secondary battery]

A sheet-like battery was produced in the same manner as in Examples A and B except that the electrolyte, the negative electrode, and the positive electrode were used, and the battery used in Example 27 and Comparative Example 5 was used.

[Practice driving]

The prepared lithium secondary battery was sandwiched between glass plates in order to improve the adhesion between the electrodes. The upper limit working potential of the positive electrode was 4.65 V based on Li / Li ^{+ at} a constant current corresponding to 0.2 C at 25 캜, Exercise operation was performed in the range of 3.0 - 4.6 V so that the open circuit voltage was 4.60 V.

[Evaluation of cycle characteristics]

A cycle in which the battery in which the practice operation was completed was charged at a constant current of 2 C at a temperature of 60 DEG C and a battery open-circuit voltage of 3.0 to 4.6 V, and then discharged at a constant current of 2 C was carried out for 200 cycles . (Discharge capacity at the 200th cycle) / (discharge capacity at the 1st cycle) x 100, the discharge capacity retention rate (cycle retention rate) was determined. Table 8 shows the evaluation results.

As can be seen from Table 8, the use of the non-aqueous liquid electrolyte according to the present invention showed a high cycle retention ratio of more than 70% even under severe conditions of 60 DEG C and 200 cycles.

[Example D]

[Selection of electrolytic solution]

The basic electrolytic solution 3 and the basic electrolytic solution 20 in which salt precipitation was not observed at 0 캜 were used as electrolytes used in Examples 28 and 6, respectively.

[Production of negative electrode]

A lithium titanium composite oxide as a negative electrode active material, carbon black as a conductive material, a binder and a binder were mixed in a solvent to prepare a slurry. Using the obtained slurry, the negative electrode used in Example 28 and Comparative Example 6 was used in the same manner as in Examples A, B, and C.

[Production of positive electrode]

Were prepared in the same manner as the positive electrodes used in Examples A and B, and used as the positive electrodes used in Examples 28 and 6.

[Production of lithium secondary battery]

A sheet-like battery was produced in the same manner as in Examples A, B, and C except that the electrolytic solution, the negative electrode, and the positive electrode were used, and the battery used in Example 28 and Comparative Example 6 was used.

[Practice driving]

The prepared sheet-shaped lithium secondary battery was sandwiched between glass plates to improve the adhesion between the electrodes, and the positive electrode potential at a constant current corresponding to 0.1 C at 25 캜 was set to 4.95 V on the basis of Li / Li ⁺ The exercise operation was carried out so that the voltage became 3.50 V. The battery was charged at a constant current of 1/3 C at an open circuit voltage of 1.50 to 3.50 V at 25 캜 and the battery was discharged at a constant current of 1/3 C, Respectively. With the above process, the practice operation of checking discharge capacity was performed.

[Evaluation of cycle characteristics]

The battery in which the practice operation is completed is charged and discharged at a constant current of 1/3 C at a temperature of 60 ° C and an open circuit voltage between 1.5 and 3.5 V and then charged and discharged at a constant current of 2 C Was carried out for 200 cycles. During this period, charging and discharging were carried out at a constant current of 1/3 C at the 50th, 100th, and 200th cycles to confirm the capacity. The discharge capacity retention rate (cycle retention rate) was calculated from the equation (discharge capacity at the 200th cycle) / (discharge capacity at the first cycle) × 100 in the charge / discharge with a constant current of 1/3 C × 100. Also, the amount of generated gas and the resistance of the battery in which the practice operation was completed were measured. The evaluation results are shown in Table 9.

As can be seen from Table 9, the use of the non-aqueous liquid electrolyte according to the present invention showed a high cycle retention ratio exceeding 70% even under harsh conditions of 60 DEG C and 200 cycles, and further suppressed gas generation. That is, even when a lithium-titanium composite oxide is used as the negative electrode, a certain amount of EC is coexistent under the high-voltage condition of EC, as in the case of using carbon in the negative electrode, And suggests the specificity of EC in a high voltmeter.

Industrial availability

The non-aqueous liquid electrolyte secondary battery of the present invention can be used for various known applications. Specific examples include notebook PCs, pen input PCs, mobile PCs, electronic book players, cell phones, smart phones, portable telephones, portable copiers, portable printers, headphone stereos, video movies, liquid crystal televisions, handy cleaners, A portable CD, a mini disk, a transceiver, an electronic notebook, an electronic desk calculator, a memory card, a portable tape recorder, a radio, a backup power source, a motor, a motorcycle, Tools, strobes, cameras, power sources for leveling loads, and natural energy storage power supplies.

Claims (15)

A nonaqueous electrolyte solution containing a lithium salt and a nonaqueous solvent dissolving the lithium salt,
Based liquid electrolyte used in a non-aqueous liquid electrolyte secondary battery having an upper limit operating potential of the positive electrode of 4.3 V or more based on Li / Li ⁺
Wherein the non-aqueous liquid electrolyte contains a cyclic carbonate represented by the following general formula (1), a fluorinated cyclic carbonate represented by the following general formula (2), and a difluorophosphate and represented by the general formulas (1) and (2) (1) and (2) are contained in an amount of not more than 100% by volume of the nonaqueous solvent, and more than 15% by volume of the cyclic carbonate represented by the general formula (1) Is 25 vol% or more of the non-aqueous solvent.
[Chemical Formula 1]

(In the general formula (1), R ₁ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different)
(2)

(In the general formula (2), R ₂ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different) The method according to claim 1,
A non-aqueous liquid electrolyte characterized by containing, in the non-aqueous liquid electrolyte, at least 20% by volume of the cyclic carbonate represented by the general formula (1) in the non-aqueous solvent. The method according to claim 1,
The non-aqueous liquid electrolyte according to claim 1, wherein R ₁ in the general formula (1) is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The method according to claim 1,
Wherein the cyclic carbonate represented by the general formula (1) is at least one selected from ethylene carbonate and propylene carbonate. The method according to claim 1,
Wherein the fluorinated cyclic carbonate represented by the general formula (2) is at least one selected from the group consisting of 4-fluoroethylene carbonate and 4,5-difluoroethylene carbonate. The method according to claim 1,
Further, it is preferable to contain a fluorinated chain type carbonate represented by the following general formula (3)
Wherein the total amount of the carbonate represented by the general formulas (1), (2) and (3) is not more than 100% by volume of the non-aqueous solvent.
(3)

(In the general formula (3), R ₃ may have a substituent or a hydrocarbon group containing at least one fluorine, R ₄ represents a hydrocarbon group which may have a substituent, R ₃ and R ₄ may be the same or different, do) The method according to claim 6,
Wherein the total amount of the carbonate represented by the general formulas (1) to (3) in the non-aqueous liquid electrolyte is 50% by volume or more of the non-aqueous liquid. The method according to claim 6,
A non-aqueous liquid electrolyte characterized by containing at least 5% by volume of a fluorinated chain-like carbonate represented by the general formula (3) in the non-aqueous liquid electrolyte. The method according to claim 6,
Wherein the fluorinated chain type carbonate represented by the general formula (3) contains trifluoroethyl methyl carbonate. 10. The method according to any one of claims 1 to 9,
Wherein the difluorophosphate is LiPO ₂ F ₂ . 10. The method according to any one of claims 1 to 9,
A nonaqueous electrolyte solution further containing at least one compound selected from the group consisting of an unsaturated cyclic carbonate, a cyclic sulfonic acid ester, a compound having a cyano group, and a compound having an isocyanato group. 10. The method according to any one of claims 1 to 9,
A nonaqueous electrolyte solution further containing at least one compound selected from the group consisting of LiBF ₄ , FSO ₃ Li, LiN (FSO ₂ ) ₂ , lithium oxalato borate salts, and lithium oxalato phosphate salts. A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte solution containing a lithium salt and a nonaqueous solvent dissolving the lithium salt, a negative electrode capable of lithium ion intercalation and deintercalation, and a positive electrode, A nonaqueous electrolyte secondary battery according to any one of the preceding claims, characterized in that it is a nonaqueous electrolyte. 14. The method of claim 13,
Wherein the positive electrode contains a positive electrode active material containing at least one selected from the group consisting of lithium transition metal compounds represented by the following general formulas (4) to (6).
Li [Li _a M _x Mn _{2- x a} ] O _{4 +} (4)
(Wherein 0? A? 0.3, 0.4 <x <1.1 and -0.5 <delta <0.5, and M is at least one of transition metals selected from Ni, Cr, Fe, )
Li _x M1 _y M2 _z O _2-delta ... (5)
(In the formula (5), 1? X? 1.3, 0? Y? 1, 0? Z? 0.3 and -0.1?? 0.1, M1 represents Ni, Co and / or Mn, M2 represents Fe , At least one element selected from Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, Ta, Be, Al, Ca, Sc and Zr )
αLi ₂ MO ₃ (1-α) LiM'O ₂ ... (6)
(Wherein, in the formula (6), 0 < alpha < 1, M represents at least one of the metal elements having an average oxidation number of +4, and M 'represents at least one metal element having an average oxidation number of +3) 14. The method of claim 13,
Wherein the negative electrode contains a negative electrode active material comprising graphite particles.