JP2009218057A - Electrolytic solution and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery which can improve cycle characteristics and a preservation property. <P>SOLUTION: The secondary battery is provided with a cathode 21 and an anode 22 and an electrolytic solution as well, and the electrolytic solution is impregnated into a separator provided between the cathode 21 and the anode 22. A solvent of the electrolytic solution contains an isocyanate compound having a portion in which an isocyanate group and an electron attractive group (carbonyl group) are combined. As compared with a case where the solvent does not contain the above isocyanate compound or contains other isocyanate compound than the above, a chemical stability of the electrolytic solution is improved and a decomposing reaction of the electrolytic solution is controlled. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrolytic solution containing a solvent and a secondary battery using the same.

  In recent years, portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, or a laptop computer have been widely used, and there is a strong demand for miniaturization, weight reduction, and long life. Accordingly, as a power source for portable electronic devices, development of a battery, in particular, a secondary battery that is lightweight and capable of obtaining a high energy density is underway.

  Among these, secondary batteries that use the insertion and extraction of lithium in charge and discharge reactions (so-called lithium ion secondary batteries) and secondary batteries that use precipitation and dissolution of lithium (so-called lithium metal secondary batteries) are lead batteries. It is highly anticipated because it has a higher energy density than nickel cadmium batteries.

As for the composition of the electrolytic solution used in these secondary batteries, a technique using a compound having an isocyanate group (—NCO) (isocyanate compound) has been proposed in order to improve cycle characteristics and storage characteristics. As this isocyanate compound, a compound in which one or two or more isocyanate groups are introduced into a benzene ring (for example, see Patent Document 1), a low molecular weight (500 or less) compound (for example, see Patent Document 2), and the like. , X-NCO (X is hydrogen or aliphatic hydrocarbon, etc.) or Z-Y-NCO (Z is hydrogen or aliphatic hydrocarbon, Y is -S (= O) _2- or aliphatic. A compound represented by a hydrocarbon (for example, see Patent Document 3) or a compound represented by an OCN-R-NCO (R is an aliphatic carbon chain or the like) (for example, Patent Document 3). 4, etc.) are used.
JP 2002-008719 A JP 2005-259641 A JP 2006-164759 A JP 2007-242411 A

  In recent years, portable electronic devices have become more sophisticated and multifunctional, and their power consumption tends to increase. Accordingly, charging and discharging of secondary batteries used in portable electronic devices are frequently repeated, and the cycle characteristics are likely to deteriorate. In addition, portable electronic devices are widely used in a wide variety of fields, and secondary batteries can be exposed to high-temperature atmosphere during transportation, use, or portability, so storage characteristics are likely to deteriorate. It is in. For this reason, the further improvement is desired regarding the cycling characteristics and storage characteristics of a secondary battery.

  The present invention has been made in view of such problems, and an object thereof is to provide an electrolytic solution and a secondary battery that can improve cycle characteristics and storage characteristics.

  The electrolytic solution of the present invention includes a solvent containing an isocyanate compound represented by Chemical Formula 1.

（Ｒ１はｚ価の有機基であり、ｚは２以上の整数である。ただし、カルボニル基中の炭素原子はＲ１中の炭素原子に結合している。）

(R1 is a z-valent organic group, and z is an integer of 2 or more, provided that the carbon atom in the carbonyl group is bonded to the carbon atom in R1.)

  The secondary battery of the present invention includes an electrolyte solution together with a positive electrode and a negative electrode, and the electrolyte solution includes a solvent containing an isocyanate compound represented by Chemical Formula 2.

（Ｒ１はｚ価の有機基であり、ｚは２以上の整数である。ただし、カルボニル基中の炭素原子はＲ１中の炭素原子に結合している。）

(R1 is a z-valent organic group, and z is an integer of 2 or more, provided that the carbon atom in the carbonyl group is bonded to the carbon atom in R1.)

  The above-mentioned “organic group” is a general term for groups having a carbon chain or carbocycle as a basic skeleton, and may have one or more elements other than carbon. As an example, examples of the “divalent organic group” include a linear alkylene group.

  According to the electrolytic solution of the present invention, since the solvent contains the isocyanate compound shown in Chemical Formula 1, compared with the case where it does not contain it or other isocyanate compounds, Stability is improved. Thereby, according to the secondary battery provided with the electrolytic solution of the present invention, since the decomposition reaction of the electrolytic solution is suppressed, cycle characteristics and storage characteristics can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An electrolytic solution according to an embodiment of the present invention is used for an electrochemical device such as a secondary battery, and includes a solvent and an electrolyte salt dissolved in the solvent.

  The solvent contains an isocyanate compound represented by Chemical formula 3. This is because the chemical stability of the electrolytic solution is improved. The isocyanate compound shown in Chemical Formula 3 has z sites where an isocyanate group and an electron-withdrawing group (carbonyl group) are bonded, and the z sites are bonded to R1.

（Ｒ１はｚ価の有機基であり、ｚは２以上の整数である。ただし、カルボニル基中の炭素原子はＲ１中の炭素原子に結合している。）

(R1 is a z-valent organic group, and z is an integer of 2 or more, provided that the carbon atom in the carbonyl group is bonded to the carbon atom in R1.)

  The “organic group” described for R1 in Chemical Formula 3 is a general term for groups having a carbon chain or carbocycle as a basic skeleton. The “organic group” may be a group having any structure as long as it has a carbon chain or a carbocyclic ring as a basic skeleton, and one or two elements other than carbon. The above may be included as constituent elements. Examples of the “other elements” include hydrogen, oxygen, and halogen. The carbon chain may be linear or branched having one or more side chains.

  The above-mentioned “other elements” may be included in any form in the “organic group”. The “form” means the number or combination of elements and can be arbitrarily set. Specifically, examples of the form containing hydrogen include a part of an alkylene group and an arylene group. Examples of the form containing oxygen include an ether bond (—O—). Examples of the form containing halogen include a part of a halogenated alkylene group. The type of the halogen is not particularly limited, but among them, fluorine is preferable. This is because the chemical stability of the electrolytic solution is higher than that of other halogens. The form in which the above halogen is contained is one in which hydrogen in R1 is substituted with halogen. In this case, only a part of hydrogen may be replaced by halogen, or all of hydrogen may be replaced by halogen. Of course, the form containing hydrogen, oxygen and halogen may be other forms than the above.

  However, the carbon atoms in the z carbonyl groups are not bonded to atoms (for example, oxygen atoms) other than the carbon atom in R1, and are always bonded to the carbon atoms.

  R1 may be a derivative of a group constituted by the series of forms described above. This “derivative” means a group in which one or two or more substituents are introduced into the above-described series of groups, and the type of the substituents can be arbitrarily set.

  Among them, the isocyanate compound shown in Chemical formula 3 is preferably a compound represented by Chemical formula 4. Since the number of z (number of sites where the isocyanate group and carbonyl group are bonded) can be kept low, excellent compatibility when the isocyanate compound is mixed with other solvents and used in the electrolyte This is because the isocyanate compound preferentially reacts (decomposes) during the electrode reaction, thereby inhibiting the decomposition reaction of other solvents and the like. The compound shown in Chemical formula 4 is a compound in which R1 in Chemical formula 3 is a divalent group and z is z = 2.

（Ｒ２は２価の有機基である。ただし、カルボニル基中の炭素原子はＲ２中の炭素原子に結合している。）

(R2 is a divalent organic group. However, the carbon atom in the carbonyl group is bonded to the carbon atom in R2.)

  As in the case described for R1 in Chemical Formula 3, R2 in Chemical Formula 4 may have any structure as a whole as long as it is a divalent organic group. Examples of R2 that is a divalent organic group include a linear or branched alkylene group, an arylene group, a group in which an arylene group and an alkylene group are bonded, and an alkylene group and an ether bond. And groups obtained by halogenating them. The “divalent group having an arylene group and an alkylene group” may be a group in which one arylene group and one alkylene group are bonded, or two alkylene groups may be bonded via one arylene group. Or a bonded group. The “group in which an alkylene group and an ether bond are bonded” means a group in which two alkylene groups are bonded through one ether bond. Further, the “group in which they are halogenated” is a group in which at least a part of hydrogen in the above-described alkylene group or the like is substituted with a halogen. The number and order of the above-described alkylene group, arylene group or ether bond can be arbitrarily set. Of course, R2 may be a group other than those described above.

  When R2 is a branched alkylene group, the number of carbon atoms can be arbitrarily set, but it is preferably 2 or more and 10 or less, more preferably 2 or more and 6 or less, and more preferably 2 or more and 4 or less. More preferably, it is as follows. When R2 is a group in which an arylene group and an alkylene group are bonded, a group in which two alkylene groups are bonded through one arylene group is preferable. In this case, the number of carbon atoms can be set arbitrarily, but among them, 8 is preferable. In any case, high chemical stability can be obtained in the electrolytic solution, and excellent compatibility can be obtained.

When R2 is a group in which an alkylene group and an ether bond are bonded, the number of carbon atoms can be arbitrarily set. Among them, it is preferably 2 or more and 12 or less, and preferably 4 or more and 12 or less. More preferred. In this case, in particular, R ₂ is preferably a group represented by —CH ₂ —CH ₂ — (O—CH ₂ —CH ₂ ) _n —, and n is more preferably 1 or more and 3 or less. . This is because high chemical stability can be obtained in the electrolytic solution and excellent compatibility can be obtained.

  Specific examples of R2 include linear alkylene groups represented by chemical formulas (1) to (7), branched alkylene groups represented by chemical formulas (1) to (9), An arylene group represented by (1) to (3) in Chemical Formula 7, a group in which an arylene group represented by (1) to (3) in Chemical Formula 8 is bonded to an alkylene group, or (1) in Chemical Formula 9 And a group in which an alkylene group represented by (13) and an ether bond are bonded. In addition, as a group obtained by halogenating the above-described series of groups, a group obtained by halogenating a group in which an alkylene group and an ether bond are bonded as represented by Chemical Formulas (1) to (9) can be given. It is done. Of course, it is not limited to a group in which an alkylene group and an ether bond are bonded, and other alkylene groups and the like may be halogenated.

In particular, R2 is preferably a linear alkylene group. This is because excellent compatibility and reactivity can be obtained. Among them, when R2 is a linear alkyl group, the carbon number thereof is preferably 4 or less, and more preferably 3 or less. This is because more excellent compatibility and reactivity can be obtained stably. Examples of such a preferable linear alkyl group include an ethylene group having 2 carbon atoms (—C ₂ H ₄ —) and a propylene group having 3 carbon atoms (—C ₃ H ₆ —). Can be mentioned.

  Specific examples of the compound represented by Chemical formula 4 include the compounds represented by Chemical formulas (1) and (2). This is because they are easily available and high chemical stability and excellent solubility can be obtained in the electrolytic solution.

  The content of the isocyanate compound shown in Chemical Formula 3 in the solvent is not particularly limited, but is preferably 0.01% by weight or more and 5% by weight or less. This is because high chemical stability can be obtained in the electrolytic solution. Specifically, if the content is less than 0.01% by weight, the chemical stability of the electrolytic solution may not be obtained sufficiently and stably. If the content is more than 5% by weight, the electrochemical There is a possibility that the main electrical performance of the device (for example, the battery capacity in the secondary battery) is deteriorated.

  The series of compounds described as the compounds shown in Chemical Formula 3 may be used alone or in combination of two or more. Needless to say, the compound shown in Chemical Formula 3 is not limited to the compounds shown in Chemical Formula 4 and Chemical Formula 11 as long as it has the structure shown in Chemical Formula 3.

  This solvent preferably contains one or more of non-aqueous solvents such as other organic solvents together with the isocyanate compound shown in Chemical formula 3. The series of solvents described below may be arbitrarily combined.

  Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2 -Methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, butyric acid Methyl, methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-me Examples thereof include tiloxazolidinone, N, N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, and dimethyl sulfoxide. Among these, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. In this case, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, a relative dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, viscosity) ≦ 1 mPa · s) is more preferable. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

  The solvent contains at least one of a chain carbonate having a halogen represented by Chemical Formula 12 as a constituent element and a cyclic carbonate having a halogen represented by Chemical Formula 13 as a constituent element. preferable. This is because when the electrolytic solution is used in an electrochemical device, a stable protective film is formed on the surface of the electrode, so that the decomposition reaction of the electrolytic solution is suppressed.

（Ｒ１１〜Ｒ１６は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

（Ｒ１７〜Ｒ２０は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R17 to R20 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

  In addition, R11 to R16 in Chemical formula 12 may be the same or different. The same applies to R17 to R20 in Chemical formula 13. The “halogenated alkyl group” described for R11 to R16 or R17 to R20 is a group in which at least a part of hydrogen in the alkyl group is substituted with halogen. The type of the halogen is not particularly limited, and examples thereof include at least one selected from the group consisting of fluorine, chlorine and bromine, and among them, fluorine is preferable. This is because a high effect can be obtained. Of course, other halogens may be used.

  The number of halogens is preferably two rather than one, and may be three or more. This is because the ability to form a protective film is increased and a stronger and more stable protective film is formed, so that the decomposition reaction of the electrolytic solution is further suppressed.

  Examples of the chain carbonate having a halogen shown in Chemical formula 12 include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like. These may be single and multiple types may be mixed. Of these, bis (fluoromethyl) carbonate is preferred. This is because a high effect can be obtained.

  Examples of the cyclic carbonate having a halogen shown in Chemical formula 13 include a series of compounds represented by Chemical formula 14 and Chemical formula 15. That is, 4-fluoro-1,3-dioxolan-2-one of (1) shown in Chemical formula 14, 4-chloro-1,3-dioxolan-2-one of (2), 4,5 of (3) -Difluoro-1,3-dioxolan-2-one, (4) tetrafluoro-1,3-dioxolan-2-one, (5) 4-chloro-5-fluoro-1,3-dioxolan-2-one ON, (6) 4,5-dichloro-1,3-dioxolan-2-one, (7) tetrachloro-1,3-dioxolan-2-one, (8) 4,5-bistrifluoromethyl 1,3-dioxolan-2-one, 4-trifluoromethyl-1,3-dioxolan-2-one of (9), 4,5-difluoro-4,5-dimethyl-1,3 of (10) -Dioxolan-2-one, 4,4-difluoro of (11) -5-methyl-1,3-dioxolan-2-one, and the like 5,5-difluoro-1,3-dioxolan-2-one (12). Further, 4-fluoro-5-trifluoromethyl-1,3-dioxolan-2-one of (1) shown in Chemical formula 15, 4-methyl-5-trifluoromethyl-1,3-dioxolane of (2) 2-one, 4-fluoro-4,5-dimethyl-1,3-dioxolan-2-one of (3), 5- (1,1-difluoroethyl) -4,4-difluoro- of (4) 1,3-dioxolan-2-one, 4,5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one in (5), 4-ethyl-5-fluoro-1, in (6) 3-dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one of (7), 4-ethyl-4,5,5-trifluoro-1 of (8) , 3-Dioxolan-2-one, 4-fluoro-4-methyl- of (9) , 3-dioxolane-2-one. These may be single and multiple types may be mixed.

  Of these, 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one is preferred, and 4,5-difluoro-1,3-dioxolan-2-one is preferred. More preferred. In particular, 4,5-difluoro-1,3-dioxolan-2-one is preferably a trans isomer rather than a cis isomer. This is because it is easily available and a high effect can be obtained.

  Moreover, it is preferable that the solvent contains the cyclic carbonate which has the unsaturated bond represented by Chemical formula 16-Chemical formula 18. This is because the chemical stability of the electrolytic solution is further improved. These may be single and multiple types may be mixed.

（Ｒ２１およびＲ２２は水素基あるいはアルキル基である。）

(R21 and R22 are a hydrogen group or an alkyl group.)

（Ｒ２３〜Ｒ２６は水素基、アルキル基、ビニル基あるいはアリル基であり、それらのうちの少なくとも１つはビニル基あるいはアリル基である。）

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

（Ｒ２７はアルキレン基である。）

(R27 is an alkylene group.)

  The cyclic carbonate having an unsaturated bond shown in Chemical formula 16 is a vinylene carbonate-based compound. Examples of the vinylene carbonate compound include vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one), and ethyl vinylene carbonate (4-ethyl). -1,3-dioxol-2-one), 4,5-dimethyl-1,3-dioxol-2-one, 4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1, Examples include 3-dioxol-2-one or 4-trifluoromethyl-1,3-dioxol-2-one, among which vinylene carbonate is preferable. This is because it is easily available and a high effect can be obtained.

  The cyclic carbonate having an unsaturated bond shown in Chemical formula 17 is a vinyl ethylene carbonate compound. Examples of the vinyl carbonate-based compound include vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one, and 4-ethyl. -4-vinyl-1,3-dioxolan-2-one, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolane-2 -One, 4,4-divinyl-1,3-dioxolan-2-one, 4,5-divinyl-1,3-dioxolan-2-one, and the like, among which vinyl ethylene carbonate is preferable. This is because it is easily available and a high effect can be obtained. Of course, as R23 to R26, all may be vinyl groups, all may be allyl groups, or vinyl groups and allyl groups may be mixed.

  The cyclic carbonate having an unsaturated bond shown in Chemical formula 18 is a methylene ethylene carbonate compound. Examples of the methylene ethylene carbonate compound include 4-methylene-1,3-dioxolan-2-one, 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one, and 4,4-diethyl-5. -Methylene-1,3-dioxolan-2-one and the like. This methylene ethylene carbonate compound may have one methylene group (compound shown in Chemical formula 18) or two methylene groups.

  The cyclic carbonate having an unsaturated bond may be catechol carbonate (catechol carbonate) having a benzene ring in addition to those shown in Chemical formula 16 to Chemical formula 18.

  The electrolyte salt contains, for example, one or more light metal salts such as a lithium salt. The series of electrolyte salts described below may be arbitrarily combined.

  Examples of the lithium salt include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate. This is because excellent battery capacity, cycle characteristics and storage characteristics can be obtained. Among these, lithium hexafluorophosphate is preferable. This is because a higher effect can be obtained because the internal resistance is lowered.

  This electrolyte salt preferably contains at least one member selected from the group consisting of compounds represented by Chemical Formulas 19 to 21. This is because a higher effect can be obtained when used together with the above-described lithium hexafluorophosphate or the like. In addition, R31 and R33 in Chemical formula 19 may be the same or different. The same applies to R41 to R43 in Chemical Formula 20 and R51 and R52 in Chemical Formula 21.

（Ｘ３１は長周期型周期表における１族元素あるいは２族元素、またはアルミニウムである。Ｍ３１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｒ３１はハロゲン基である。Ｙ３１は−（Ｏ＝）Ｃ−Ｒ３２−Ｃ（＝Ｏ）−、−（Ｏ＝）Ｃ−Ｃ（Ｒ３３）₂ −あるいは−（Ｏ＝）Ｃ−Ｃ（＝Ｏ）−である。ただし、Ｒ３２はアルキレン基、ハロゲン化アルキレン基、アリーレン基あるいはハロゲン化アリーレン基である。Ｒ３３はアルキル基、ハロゲン化アルキル基、アリール基あるいはハロゲン化アリール基である。なお、ａ３は１〜４の整数であり、ｂ３は０、２あるいは４であり、ｃ３、ｄ３、ｍ３およびｎ３は１〜３の整数である。）

(X31 is a group 1 element or group 2 element in the long-period periodic table, or aluminum. M31 is a transition metal element, or a group 13 element, group 14 element, or group 15 element in the long-period periodic table. R31 Y31 is — (O═) C—R32—C (═O) —, — (O═) C—C (R33) ₂ — or — (O═) C—C (═O) Where R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, and a3 is (It is an integer of 1 to 4, b3 is 0, 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

（Ｘ４１は長周期型周期表における１族元素あるいは２族元素である。Ｍ４１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｙ４１は−（Ｏ＝）Ｃ−（Ｃ（Ｒ４１）₂ ）_b4−Ｃ（＝Ｏ）−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｃ（＝Ｏ）−、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｃ（Ｒ４３）₂ −、−（Ｒ４３）₂ Ｃ−（Ｃ（Ｒ４２）₂ ）_c4−Ｓ（＝Ｏ）₂ −、−（Ｏ＝）₂ Ｓ−（Ｃ（Ｒ４２）₂ ）_d4−Ｓ（＝Ｏ）₂ −あるいは−（Ｏ＝）Ｃ−（Ｃ（Ｒ４２）₂ ）_d4−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ４１およびＲ４３は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、それぞれのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。Ｒ４２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。なお、ａ４、ｅ４およびｎ４は１あるいは２であり、ｂ４およびｄ４は１〜４の整数であり、ｃ４は０〜４の整数であり、ｆ４およびｍ４は１〜３の整数である。）

(X41 is a group 1 element or group 2 element in the long periodic table. M41 is a transition metal element, or a group 13, element or group 15 element in the long period periodic table. Y41 is − ( O =) C- (C (R41 ) 2) b4 -C (= O) -, - (R43) 2 C- (C (R42) 2) c4 -C (= O) -, - (R43) 2 C -(C (R42) ₂ ) _c4 -C (R43) ₂ -,-(R43) ₂ C- (C (R42) ₂ ) _c4 -S (= O) ₂ -,-(O =) ₂ S- ( C (R42) ₂ ) _d4- S (= O) _2- or-(O =) C- (C (R42) ₂ ) _d4- S (= O) _2- where R41 and R43 are hydrogen groups. , An alkyl group, a halogen group, or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R42 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, wherein a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, and c4 Is an integer from 0 to 4, and f4 and m4 are integers from 1 to 3.)

（Ｘ５１は長周期型周期表における１族元素あるいは２族元素である。Ｍ５１は遷移金属元素、または長周期型周期表における１３族元素、１４族元素あるいは１５族元素である。Ｒｆはフッ素化アルキル基あるいはフッ素化アリール基であり、いずれの炭素数も１〜１０である。Ｙ５１は−（Ｏ＝）Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（＝Ｏ）−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（＝Ｏ）−、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｃ（Ｒ５２）₂ −、−（Ｒ５２）₂ Ｃ−（Ｃ（Ｒ５１）₂ ）_d5−Ｓ（＝Ｏ）₂ −、−（Ｏ＝）₂ Ｓ−（Ｃ（Ｒ５１）₂ ）_e5−Ｓ（＝Ｏ）₂ −あるいは−（Ｏ＝）Ｃ−（Ｃ（Ｒ５１）₂ ）_e5−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ５１は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。Ｒ５２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、そのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。なお、ａ５、ｆ５およびｎ５は１あるいは２であり、ｂ５、ｃ５およびｅ５は１〜４の整数であり、ｄ５は０〜４の整数であり、ｇ５およびｍ５は１〜３の整数である。）

(X51 is a group 1 element or group 2 element in the long-period periodic table. M51 is a transition metal element, or a group 13, element or group 15 element in the long-period periodic table. Rf is fluorinated. An alkyl group or a fluorinated aryl group, each having 1 to 10 carbon atoms Y51 is — (O═) C— (C (R51) ₂ ) _d5 —C (═O) —, — (R52); ₂ C- (C (R51) ₂ ) _d5 -C (= O)-,-(R52) ₂ C- (C (R51) ₂ ) _d5 -C (R52) ₂ -,-(R52) ₂ C- ( _{C (R51) 2) d5 -S} (= O) 2 -, - (O =) 2 S- (C (R51) 2) e5 -S (= O) 2 - or - (O =) C- (C _{(R51) 2) e5 -S (} = O) 2 -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group, or a halogen Kaa R52 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.)

  The long-period periodic table is represented by a revised inorganic chemical nomenclature proposed by IUPAC (International Pure and Applied Chemistry Association). Specifically, group 1 elements are hydrogen, lithium, sodium, potassium, rubidium, cesium and francium. Group 2 elements are beryllium, magnesium, calcium, strontium, barium and radium. Group 13 elements are boron, aluminum, gallium, indium and thallium. Group 14 elements are carbon, silicon, germanium, tin and lead. Group 15 elements are nitrogen, phosphorus, arsenic, antimony and bismuth.

  Examples of the compound shown in Chemical formula 19 include compounds represented by Chemical formulas (1) to (6). Examples of the compound shown in Chemical formula 20 include the compounds represented by chemical formulas (1) to (8) in Chemical formula 23. Examples of the compound represented by Chemical formula 21 include the compound represented by Chemical formula 24. It is needless to say that the compound having the structure shown in Chemical Formula 19 to Chemical Formula 21 is not limited to the compound shown in Chemical Formula 22 to Chemical Formula 24.

  The electrolyte salt may contain at least one selected from the group consisting of compounds represented by Chemical Formulas 25 to 27. This is because a higher effect can be obtained when used together with the above-described lithium hexafluorophosphate or the like. In the chemical formula 25, m and n may be the same or different. The same applies to p, q and r in Chemical Formula 27.

（ｍおよびｎは１以上の整数である。）

(M and n are integers of 1 or more.)

（Ｒ６１は炭素数が２以上４以下の直鎖状あるいは分岐状のパーフルオロアルキレン基である。）

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

（ｐ、ｑおよびｒは１以上の整数である。）

(P, q and r are integers of 1 or more.)

Examples of the chain compound shown in Chemical Formula 25 include bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ), bis (pentafluoroethanesulfonyl) imide lithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ), (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ )), (trifluoromethanesulfonyl) (heptafluoropropanesulfonyl) imide lithium ( LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ )) or (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ )) Can be mentioned. These may be single and multiple types may be mixed.

  Examples of the cyclic compound represented by Chemical formula 26 include a series of compounds represented by Chemical formula 28. That is, 1,2-perfluoroethanedisulfonylimide lithium of (1) shown in Chemical formula 28, 1,3-perfluoropropane disulfonylimide lithium of (2), 1,3-perfluorobutane of (3) Disulfonylimide lithium, 1,4-perfluorobutane disulfonylimide lithium of (4), and the like. These may be single and multiple types may be mixed. Among these, 1,2-perfluoroethanedisulfonylimide lithium is preferable. This is because a high effect can be obtained.

Examples of the chain compound shown in Chemical formula 27 include lithium tris (trifluoromethanesulfonyl) methide (LiC (CF ₃ SO ₂ ) ₃ ).

  The content of the electrolyte salt is preferably 0.3 mol / kg or more and 3.0 mol / kg or less with respect to the solvent. This is because, outside this range, the ion conductivity may be extremely lowered.

  The electrolytic solution may contain various additives along with the solvent and the electrolyte salt. This is because the chemical stability of the electrolytic solution is further improved.

  Examples of this additive include sultone (cyclic sulfonic acid ester). This sultone is, for example, propane sultone or propene sultone, among which propene sultone is preferable. These may be single and multiple types may be mixed. The content of sultone in the electrolytic solution is, for example, not less than 0.5 wt% and not more than 5 wt%.

  Moreover, as an additive, an acid anhydride is mentioned, for example. Examples of the acid anhydride include carboxylic acid anhydrides such as succinic acid anhydride, glutaric acid anhydride and maleic acid anhydride, disulfonic acid anhydrides such as ethanedisulfonic acid anhydride and propanedisulfonic acid anhydride, Examples thereof include carboxylic acid and sulfonic acid anhydrides such as benzoic acid anhydride, sulfopropionic acid anhydride and sulfobutyric acid anhydride, among which succinic acid anhydride and sulfobenzoic acid anhydride are preferable. These may be single and multiple types may be mixed. The content of the acid anhydride in the electrolytic solution is, for example, 0.5% by weight or more and 5% by weight or less.

  According to this electrolytic solution, since the solvent contains the isocyanate compound shown in Chemical formula 3, it is compared with the case where it does not contain it or the case where it contains another isocyanate compound represented by Chemical formula 29. Thus, chemical stability is improved. The isocyanate compound shown in Chemical formula 29 has a plurality of isocyanate groups in the same manner as the isocyanate compound shown in Chemical formula 3, but does not have a site where an isocyanate group and a carbonyl group are bonded. Therefore, when used in an electrochemical device such as a secondary battery, the decomposition reaction is suppressed, which can contribute to improvement of cycle characteristics and storage characteristics. In this case, if the isocyanate compound shown in Chemical formula 3 is the compound shown in Chemical formula 4 or the content of the isocyanate compound shown in Chemical formula 3 in the solvent is 0.01 wt% or more and 5 wt% or less. High effect can be obtained.

  In particular, the solvent has at least one of a chain carbonate having a halogen shown in Chemical Formula 12 and a cyclic carbonate having a halogen shown in Chemical Formula 13 or an unsaturated bond shown in Chemical Formula 16 to Chemical Formula 18. A cyclic carbonate and a higher effect can be obtained. Further, when using at least one of a chain carbonate having a halogen shown in Chemical Formula 12 and a cyclic carbonate having a halogen shown in Chemical Formula 13, the higher the number of halogens, the higher the effect. Can do.

  Further, the electrolyte salt is represented by at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate, and A higher effect can be obtained if at least one kind selected from the group consisting of the compounds and at least one kind selected from the group consisting of the compounds shown in Chemical Formulas 25 to 27 is contained.

  Furthermore, if the electrolytic solution contains sultone or an acid anhydride as an additive, a higher effect can be obtained.

  Next, usage examples of the above-described electrolytic solution will be described. Here, as an example of an electrochemical device, taking a secondary battery as an example, the electrolytic solution is used as follows.

(First secondary battery)
1 and 2 show a cross-sectional configuration of the first secondary battery, and FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. The secondary battery described here is, for example, a lithium ion secondary battery in which the capacity of the negative electrode 22 is expressed based on insertion and extraction of lithium as an electrode reactant.

  This secondary battery mainly includes a wound electrode body 20 in which a positive electrode 21 and a negative electrode 22 are laminated and wound through a separator 23 inside a substantially hollow cylindrical battery can 11 and a pair of insulating plates. 12 and 13 are accommodated. The battery structure using the cylindrical battery can 11 is called a cylindrical type.

  The battery can 11 has, for example, a hollow structure in which one end is closed and the other end is opened, and is made of a metal material such as iron, aluminum, or an alloy thereof. In addition, when the battery can 11 is comprised with iron, plating, such as nickel, may be given, for example. The pair of insulating plates 12 and 13 are arranged so as to sandwich the wound electrode body 20 from above and below and to extend perpendicularly to the wound peripheral surface.

  A battery lid 14 and a safety valve mechanism 15 and a heat sensitive resistance element (Positive Temperature Coefficient: PTC element) 16 provided inside the battery can 11 are caulked through a gasket 17 at the open end of the battery can 11. It is attached. Thereby, the inside of the battery can 11 is sealed. The battery lid 14 is made of a metal material similar to that of the battery can 11, for example. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16. In the safety valve mechanism 15, when the internal pressure becomes a certain level or more due to an internal short circuit or external heating, the disk plate 15 </ b> A is reversed and the electric power between the battery lid 14 and the wound electrode body 20 is reversed. Connection is cut off. The heat-sensitive resistor element 16 is configured to prevent abnormal heat generation caused by a large current by limiting the current by increasing the resistance in response to a rise in temperature. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface thereof.

  A center pin 24 may be inserted in the center of the wound electrode body 20. In this wound electrode body 20, a positive electrode lead 25 made of a metal material such as aluminum is connected to the positive electrode 21, and a negative electrode lead 26 made of a metal material such as nickel is connected to the negative electrode 22. . The positive electrode lead 25 is welded to the safety valve mechanism 15 and electrically connected to the battery lid 14, and the negative electrode lead 26 is welded to the battery can 11 and electrically connected thereto.

  For example, the positive electrode 21 is obtained by providing a positive electrode active material layer 21B on both surfaces of a positive electrode current collector 21A having a pair of surfaces. However, the positive electrode active material layer 21B may be provided only on one surface of the positive electrode current collector 21A.

  The positive electrode current collector 21A is made of a metal material such as aluminum, nickel, or stainless steel, for example.

  The positive electrode active material layer 21B includes one or more positive electrode materials capable of inserting and extracting lithium as a positive electrode active material, and a positive electrode binder or a positive electrode conductive material as necessary. Other materials such as agents may be included.

As a positive electrode material capable of inserting and extracting lithium, for example, a lithium-containing compound is preferable. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing lithium and a transition metal element, and a phosphate compound containing lithium and a transition metal element. Especially, what contains at least 1 sort (s) of the group which consists of cobalt, nickel, manganese, and iron as a transition metal element is preferable. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Li _x M1O ₂ or Li _y M2PO ₄ . In the formula, M1 and M2 represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni). _1-z Co _z O ₂ (z <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _(1-vw) Co _v Mn _w O ₂ (v + w <1)), or lithium having a spinel structure Manganese composite oxide (LiMn ₂ O ₄ ) and the like can be mentioned. Among these, a complex oxide containing cobalt is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can be obtained. Examples of the phosphate compound containing lithium and a transition metal element include a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Is mentioned.

  In addition, examples of the positive electrode material capable of inserting and extracting lithium include oxides such as titanium oxide, vanadium oxide and manganese dioxide, disulfides such as titanium disulfide and molybdenum sulfide, and niobium selenide. And chalcogenides such as sulfur, polyaniline and polythiophene, and other conductive polymers.

  Of course, the positive electrode material capable of inserting and extracting lithium may be other than the above. Further, two or more kinds of the series of positive electrode materials described above may be mixed in any combination.

  Examples of the positive electrode binder include synthetic rubbers such as styrene butadiene rubber, fluorine rubber, and ethylene propylene diene, and polymer materials such as polyvinylidene fluoride. These may be single and multiple types may be mixed.

  Examples of the positive electrode conductive agent include carbon materials such as graphite, carbon black, acetylene black, and ketjen black. These may be single and multiple types may be mixed. The positive electrode conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

  In the negative electrode 22, for example, a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A having a pair of surfaces. However, the negative electrode active material layer 22B may be provided only on one surface of the negative electrode current collector 22A.

  The anode current collector 22A is made of, for example, a metal material such as copper, nickel, or stainless steel. The surface of the anode current collector 22A is preferably roughened. This is because the so-called anchor effect improves the adhesion between the negative electrode current collector 22A and the negative electrode active material layer 22B. In this case, the surface of the negative electrode current collector 22A only needs to be roughened at least in a region facing the negative electrode active material layer 22B. Examples of the roughening method include a method of forming fine particles by electrolytic treatment. This electrolytic treatment is a method of forming irregularities by forming fine particles on the surface of the anode current collector 22A by an electrolytic method in an electrolytic bath. The copper foil produced using the electrolytic method is generally called “electrolytic copper foil”.

  The negative electrode active material layer 22B includes one or more negative electrode materials capable of inserting and extracting lithium as a negative electrode active material, and a negative electrode binder or a negative electrode conductive material as necessary. Other materials such as agents may be included. At this time, the chargeable capacity of the negative electrode material capable of inserting and extracting lithium is preferably larger than the discharge capacity of the positive electrode. Note that details regarding the negative electrode binder and the negative electrode conductive agent are the same as, for example, the positive electrode binder and the positive electrode conductive agent, respectively.

  Examples of the negative electrode material capable of inserting and extracting lithium include materials capable of inserting and extracting lithium and having at least one of a metal element and a metalloid element as a constituent element. . This is because a high energy density can be obtained. Such a negative electrode material may be a single element or an alloy or a compound of a metal element or a metalloid element, and may have one or two or more phases thereof at least in part. The “alloy” in the present invention includes an alloy containing one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Further, the “alloy” may contain a nonmetallic element. This structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a material in which two or more of them coexist.

  Examples of the metal element or metalloid element described above include a metal element or metalloid element capable of forming an alloy with lithium. Specifically, magnesium, boron (B), aluminum, gallium (Ga), indium (In), silicon, germanium (Ge), tin, lead (Pb), bismuth (Bi), cadmium (Cd), silver ( Ag), zinc, hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd) or platinum (Pt). Among these, at least one of silicon and tin is preferable, and silicon is more preferable. This is because a high energy density can be obtained because the ability to occlude and release lithium is large.

  Examples of the negative electrode material having at least one of silicon and tin as a constituent element include, for example, a simple substance, an alloy or a compound of silicon, a simple substance, an alloy or a compound of tin, or one or more phases thereof. The material which has at least one part is mentioned.

Examples of the silicon alloy include, as the second constituent element other than silicon, tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony (Sb), and chromium. Those having at least one of the groups are mentioned. Examples of the silicon compound include those having oxygen or carbon (C), and may contain the second constituent element described above in addition to silicon. Examples of silicon alloys or compounds include SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi. ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2), SnO _w (0 <w ≦ 2) or LiSiO etc. are mentioned.

As an alloy of tin, for example, as a second constituent element other than tin, among the group consisting of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing which has at least 1 sort (s) of these is mentioned. Examples of the tin compound include those having oxygen or carbon, and may contain the above-described second constituent element in addition to tin. Examples of tin alloys or compounds include SnSiO ₃ , LiSnO, Mg ₂ Sn, and the like.

  In particular, as a negative electrode material having at least one of silicon and tin as a constituent element, for example, a material having tin and a second constituent element in addition to tin as a first constituent element is preferable. The second constituent elements are cobalt, iron, magnesium, titanium, vanadium (V), chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium (Nb), molybdenum, silver, indium, cerium (Ce), It is at least one selected from the group consisting of hafnium, tantalum (Ta), tungsten (W), bismuth and silicon. The third constituent element is at least one selected from the group consisting of boron, carbon, aluminum, and phosphorus (P). This is because having the second and third constituent elements improves the cycle characteristics.

  Among them, tin, cobalt and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the ratio of cobalt to the total of tin and cobalt (Co / (Sn + Co)) is 30. An SnCoC-containing material having a mass% of 70% by mass or less is preferable. This is because a high energy density can be obtained in such a composition range.

  This SnCoC-containing material may further contain other constituent elements as necessary. As other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, bismuth, and the like are preferable, and two or more of them may be included. . This is because a higher effect can be obtained.

  The SnCoC-containing material has a phase containing tin, cobalt, and carbon, and the phase is preferably a low crystalline or amorphous phase. This phase is a reaction phase capable of reacting with lithium, whereby excellent cycle characteristics can be obtained. The half-value width of the diffraction peak obtained by X-ray diffraction of this phase is 1.0 ° or more at a diffraction angle 2θ when CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. Is preferred. This is because lithium is occluded and released more smoothly and the reactivity with the electrolyte is reduced.

  Whether or not the diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with lithium can be easily determined by comparing X-ray diffraction charts before and after electrochemical reaction with lithium. can do. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it corresponds to a reaction phase capable of reacting with lithium. In this case, for example, a diffraction peak of a low crystalline or amorphous reaction phase is observed between 2θ = 20 ° and 50 °. This low crystalline or amorphous reaction phase contains, for example, each of the above-described constituent elements, and is considered to be mainly low-crystallized or amorphous due to carbon.

  Note that the SnCoC-containing material may have a phase containing a simple substance or a part of each constituent element in addition to a low crystalline or amorphous phase.

  In particular, in the SnCoC-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a metalloid element as another constituent element. This is because aggregation or crystallization of tin or the like is suppressed.

  As a measuring method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be cited. This XPS irradiates the sample surface with soft X-rays (Al-Kα ray or Mg-Kα ray is used in a commercial apparatus), and measures the kinetic energy of photoelectrons jumping out of the sample surface. To elemental composition in the region of several nanometers and the bonding state of the elements.

  The binding energy of the core orbital electrons of the element changes in a first approximation in correlation with the charge density on the element. For example, when the charge density of the carbon element decreases due to an interaction with an element present in the vicinity, the outer electrons such as 2p electrons decrease, so the 1s electron of the carbon element exerts a strong binding force from the shell. Will receive. That is, the binding energy increases as the charge density of the element decreases. In XPS, when the binding energy increases, the peak shifts to a high energy region.

  In XPS, if the peak of carbon 1s orbital (C1s) is graphite, it appears at 284.5 eV in an energy calibrated apparatus so that the peak of 4f orbital (Au4f) of gold atom is obtained at 84.0 eV. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element is high, for example, when it is bonded to an element more positive than carbon, the C1s peak appears in a region lower than 284.5 eV. That is, when at least a part of the carbon contained in the SnCoC-containing material is bonded to another constituent element such as a metal element or a metalloid element, the peak of the synthetic wave of C1s obtained for the SnCoC-containing material is 284. Appears in the region lower than 5 eV.

  When performing XPS measurement, it is preferable that the surface is lightly sputtered with an argon ion gun attached to the XPS apparatus when the surface is covered with surface-contaminated carbon. When the SnCoC-containing material to be measured is present in the negative electrode 22, the secondary battery is disassembled and the negative electrode 22 is taken out and then washed with a volatile solvent such as dimethyl carbonate. This is to remove the low-volatile solvent and the electrolyte salt present on the surface of the negative electrode 22. These samplings are desirably performed in an inert atmosphere.

  In XPS measurement, for example, the peak of C1s is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface of the substance, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, which is used as an energy standard. In XPS measurement, the waveform of the peak of C1s is obtained as a form including the surface contamination carbon peak and the carbon peak in the SnCoC-containing material. For example, by analyzing using commercially available software, The surface contamination carbon peak is separated from the carbon peak in the SnCoC-containing material. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  This SnCoC-containing material can be formed, for example, by melting a mixture of raw materials of each constituent element in an electric furnace, a high-frequency induction furnace, an arc melting furnace or the like and then solidifying the mixture. Also, various atomizing methods such as gas atomization or water atomization, methods using various mechanochemical reactions such as various roll methods, mechanical alloying methods, and mechanical milling methods may be used. Among these, a method using a mechanochemical reaction is preferable. This is because the SnCoC-containing material has a low crystalline or amorphous structure. In the method using the mechanochemical reaction, for example, a manufacturing apparatus such as a planetary ball mill apparatus or an attritor can be used.

  The raw material may be a mixture of individual constituent elements, but it is preferable to use an alloy for some of the constituent elements other than carbon. This is because, by adding carbon to such an alloy and synthesizing it by a method using the mechanical alloying method, a low crystallization or amorphous structure can be obtained, and the reaction time can be shortened. The raw material may be in the form of powder or a block.

  In addition to this SnCoC-containing material, an SnCoFeC-containing material having tin, cobalt, iron and carbon as constituent elements is also preferable. The composition of the SnCoFeC-containing material can be arbitrarily set. For example, as a composition when the iron content is set to be small, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the iron content is 0.3 mass% or more and 5.9 mass% %, And the ratio of cobalt to the total of tin and cobalt (Co / (Sn + Co)) is preferably 30% by mass or more and 70% by mass or less. In addition, for example, as a composition when the content of iron is set to be large, the content of carbon is 11.9 mass% or more and 29.7 mass% or less, and cobalt and iron with respect to the total of tin, cobalt, and iron The total ratio of (Co + Fe) / (Sn + Co + Fe)) is 26.4 mass% to 48.5 mass%, and the ratio of cobalt to the total of cobalt and iron (Co / (Co + Fe)) is 9.9 mass% It is preferable that it is 79.5 mass% or more. This is because a high energy density can be obtained in such a composition range. The crystallinity of the SnCoFeC-containing material, the method for measuring the bonding state of elements, the formation method, and the like are the same as those of the above-described SnCoC-containing material.

  As a negative electrode material capable of inserting and extracting lithium, a simple substance, an alloy or a compound of silicon, a simple substance, an alloy or a compound of tin, or a material having one or more phases thereof at least in part. The used negative electrode active material layer 22B is formed by using, for example, a gas phase method, a liquid phase method, a thermal spraying method, a coating method or a firing method, or two or more of these methods. In this case, it is preferable that the anode current collector 22A and the anode active material layer 22B are alloyed at least at a part of the interface. Specifically, the constituent element of the negative electrode current collector 22A may be diffused into the negative electrode active material layer 22B at the interface between them, or the constituent element of the negative electrode active material layer 22B is diffused into the negative electrode current collector 22A. These constituent elements may be diffused with each other. This is because breakage due to expansion and contraction of the negative electrode active material layer 22B during charging and discharging is suppressed, and electron conductivity between the negative electrode current collector 22A and the negative electrode active material layer 22B is improved.

  As the vapor phase method, for example, physical deposition method or chemical deposition method, specifically, vacuum deposition method, sputtering method, ion plating method, laser ablation method, thermal chemical vapor deposition (CVD) Or plasma chemical vapor deposition. As the liquid phase method, a known method such as electrolytic plating or electroless plating can be used. The application method is, for example, a method in which a particulate negative electrode active material is mixed with a binder and then dispersed in a solvent and applied. The baking method is, for example, a method in which a heat treatment is performed at a temperature higher than the melting point of a binder or the like after coating by a coating method. Regarding the firing method, a known method can be used, and examples thereof include an atmosphere firing method, a reaction firing method, and a hot press firing method.

  In addition to the above, examples of the anode material capable of inserting and extracting lithium include a carbon material. Examples of the carbon material include graphitizable carbon, non-graphitizable carbon having a (002) plane spacing of 0.37 nm or more, and graphite having a (002) plane spacing of 0.34 nm or less. It is. More specifically, there are pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon or carbon blacks. Of these, the cokes include pitch coke, needle coke, petroleum coke, and the like. The organic polymer compound fired body is obtained by firing and carbonizing a phenol resin, a furan resin, or the like at an appropriate temperature. The carbon material is preferable because the change in crystal structure associated with insertion and extraction of lithium is very small, so that a high energy density can be obtained, and excellent cycle characteristics can be obtained. The shape of the carbon material may be any of fibrous, spherical, granular or scale-like.

  Further, examples of the negative electrode material capable of inserting and extracting lithium include metal oxides and polymer compounds capable of inserting and extracting lithium. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

  Of course, the negative electrode material capable of inserting and extracting lithium may be other than the above. Moreover, two or more kinds of the series of negative electrode materials described above may be mixed in any combination.

  The negative electrode active material described above has a plurality of particles. That is, the negative electrode active material layer 22B has a plurality of particulate negative electrode active materials (hereinafter simply referred to as “negative electrode active material particles”). It is formed by. However, the negative electrode active material particles may be formed by a method other than the gas phase method.

  When the negative electrode active material particles are formed by a deposition method such as a vapor phase method, the negative electrode active material particles may have a single layer structure formed through a single deposition step, or may be a plurality of times. It may have a multilayer structure formed through the deposition process. However, when the negative electrode active material particles are formed by a vapor deposition method that involves high heat during deposition, the negative electrode active material particles preferably have a multilayer structure. By performing the deposition process of the negative electrode material in a plurality of times (the negative electrode material is sequentially formed and deposited thinly), the negative electrode current collector 22A is exposed to high heat compared to the case where the deposition process is performed once. This is because the time required for heat treatment is shortened and it is difficult to receive thermal damage.

  For example, the negative electrode active material particles are preferably grown from the surface of the negative electrode current collector 22A in the thickness direction of the negative electrode active material layer 22B, and are connected to the negative electrode current collector 22A at the root. This is because the expansion and contraction of the negative electrode active material layer 22B are suppressed during charging and discharging. In this case, the negative electrode active material particles are formed by a vapor phase method or the like, and as described above, it is preferable that the negative electrode active material particles are alloyed at least at a part of the interface with the negative electrode current collector 22A. Specifically, the constituent element of the negative electrode current collector 22A may be diffused into the negative electrode active material particles at the interface between them, or the constituent element of the negative electrode active material particles may be diffused into the negative electrode current collector 22A. Alternatively, both constituent elements may be diffused with each other.

  In particular, the negative electrode active material layer 22B has an oxide-containing film that covers the surface of the negative electrode active material particles (a region that will be in contact with the electrolyte solution if no oxide-containing film is provided), if necessary. It is preferable. This is because the oxide-containing film functions as a protective film against the electrolytic solution, and even when charging and discharging are repeated, the decomposition reaction of the electrolytic solution is suppressed, so that cycle characteristics and storage characteristics are improved. The oxide-containing film may cover the entire surface of the negative electrode active material particles, or may cover only a part of the surface, but it is preferable to cover the entire surface. This is because the decomposition reaction of the electrolytic solution is effectively suppressed.

  This oxide-containing film contains, for example, at least one oxide selected from the group consisting of silicon, germanium, and tin, and among these, it is preferable to contain an oxide of silicon. This is because the entire surface of the negative electrode active material particles can be easily covered and an excellent protective action can be obtained. Of course, the oxide-containing film may contain an oxide other than the above.

  The oxide-containing film is formed by, for example, a gas phase method or a liquid phase method, and among these, it is preferable that the oxide-containing film is formed by a liquid phase method. This is because the surface of the negative electrode active material particles can be easily covered over a wide range. Examples of the liquid phase method include a liquid phase precipitation method, a sol-gel method, a coating method, or a dip coating method. Among these, the liquid phase precipitation method, the sol-gel method, or the dip coating method is preferable, and the liquid phase precipitation method is more preferable. This is because a higher effect can be obtained. Note that the oxide-containing film may be formed by a single forming method among the above-described series of forming methods, or may be formed by two or more forming methods.

  In addition, the negative electrode active material layer 22B may be formed in gaps in the negative electrode active material layer 22B, that is, gaps between negative electrode active material particles described later with reference to FIGS. It is preferable to have a metal material that does not alloy with lithium in the gap. Since a plurality of negative electrode active material particles are bound via a metal material and the expansion and contraction of the negative electrode active material layer 22B are suppressed by the presence of the metal material in the gaps described above, cycle characteristics and storage characteristics are improved. It is because it improves.

  This metal material has, for example, a metal element that does not alloy with lithium as a constituent element. Examples of such a metal element include at least one selected from the group consisting of iron, cobalt, nickel, zinc, and copper, and among these, cobalt is preferable. This is because the metal material can easily enter the gap, and an excellent binding action can be obtained. Of course, the metal material may have a metal element other than the above. However, the “metal material” mentioned here is not limited to a simple substance, but is a broad concept that includes alloys and metal compounds.

  The metal material is formed by, for example, a gas phase method or a liquid phase method, and among these, it is preferably formed by a liquid phase method. This is because the metal material easily enters the gap in the negative electrode active material layer 22B. Examples of the liquid phase method include an electrolytic plating method and an electroless plating method, among which the electrolytic plating method is preferable. This is because the metal material is more likely to enter the gaps and the formation time thereof can be shortened. In addition, the metal material may be formed by a single forming method among the above-described series of forming methods, or may be formed by two or more kinds of forming methods.

  Note that the negative electrode active material layer 22B may include only one of the oxide-containing film or the metal material described above, or may include both. However, in order to further improve the cycle characteristics and the storage characteristics, it is preferable to have both. Further, in the case where both the oxide-containing film and the metal material are included, either of them may be formed first, but in order to further improve cycle characteristics and storage characteristics, the oxide-containing film is formed first. Is preferred.

  Here, the detailed configuration of the negative electrode 22 will be described with reference to FIGS.

  First, the case where the negative electrode active material layer 22B has an oxide-containing film together with a plurality of negative electrode active material particles will be described. FIG. 3 schematically shows a cross-sectional structure of the negative electrode 22 of the present invention, and FIG. 4 schematically shows a cross-sectional structure of the negative electrode of the reference example. 3 and 4 show a case where the negative electrode active material particles have a single layer structure.

  In the negative electrode of the present invention, as shown in FIG. 3, for example, when a negative electrode material is deposited on the negative electrode current collector 22A by a vapor phase method such as a vapor deposition method, a plurality of negative electrodes are formed on the negative electrode current collector 22A. Active material particles 221 are formed. In this case, when the surface of the negative electrode current collector 22A is roughened and a plurality of protrusions (for example, fine particles formed by electrolytic treatment) exist on the surface, the negative electrode active material particles 221 have the protrusions described above. Therefore, the plurality of negative electrode active material particles 221 are arranged on the negative electrode current collector 22A and connected to the surface of the negative electrode current collector 22A at the root. After that, for example, when the oxide-containing film 222 is formed on the surface of the negative electrode active material particle 221 by a liquid phase method such as a liquid phase precipitation method, the oxide-containing film 222 substantially covers the surface of the negative electrode active material particle 221. The entire surface is covered, and in particular, a wide range from the top of the negative electrode active material particle 221 to the root is covered. This wide covering state by the oxide-containing film 222 is a characteristic obtained when the oxide-containing film 222 is formed by a liquid phase method. That is, when the oxide-containing film 222 is formed by the liquid phase method, the covering action extends not only to the top of the negative electrode active material particles 221 but also to the root, so that the base is covered with the oxide-containing film 222.

  On the other hand, in the negative electrode of the reference example, as shown in FIG. 4, for example, after the plurality of negative electrode active material particles 221 are formed by the vapor phase method, the oxide-containing film 223 is similarly formed by the vapor phase method. When formed, the oxide-containing film 223 covers only the tops of the negative electrode active material particles 221. This narrow-range covering state by the oxide-containing film 223 is a characteristic obtained when the oxide-containing film 223 is formed by a vapor phase method. That is, when the oxide-containing film 223 is formed by a vapor phase method, the covering action does not reach the root of the negative electrode active material particles 221, but the base is not covered by the oxide-containing film 223.

  Although FIG. 3 illustrates the case where the negative electrode active material layer 22B is formed by a vapor phase method, the negative electrode active material layer 22B may be formed by another forming method such as a coating method or a sintering method. Similarly, the oxide-containing film is formed so as to cover almost the entire surface of the plurality of negative electrode active material particles.

  Next, the case where the negative electrode active material layer 22B includes a metal material that does not alloy with lithium together with the plurality of negative electrode active material particles will be described. FIG. 5 shows an enlarged cross-sectional structure of the negative electrode 22, (A) is a scanning electron microscope (SEM) photograph (secondary electron image), and (B) is an SEM shown in (A). It is a schematic picture of the statue. FIG. 5 shows a case where a plurality of negative electrode active material particles 221 have a multilayer structure in the particles.

  When the negative electrode active material particles 221 have a multilayer structure, a plurality of gaps 224 are generated in the negative electrode active material layer 22B due to the arrangement structure, multilayer structure, and surface structure of the plurality of negative electrode active material particles 221. Yes. The gap 224 mainly includes two types of gaps 224A and 224B classified according to the cause of occurrence. The gap 224 </ b> A is generated between adjacent negative electrode active material particles 221, and the gap 224 </ b> B is generated between layers in the negative electrode active material particles 221.

  Note that a void 225 may be formed on the exposed surface (outermost surface) of the negative electrode active material particles 221. The void 225 is generated between the protrusions as a whisker-like fine protrusion (not shown) is formed on the surface of the negative electrode active material particle 221. The void 225 may be generated over the entire exposed surface of the negative electrode active material particles 221 or may be generated only in part. However, since the above-described whisker-like protrusions are generated on the surface every time the negative electrode active material particles 221 are formed, the void 225 is generated not only on the exposed surface of the negative electrode active material particles 221 but also between the layers. There is.

  FIG. 6 shows another cross-sectional structure of the negative electrode 22 and corresponds to FIG. The negative electrode active material layer 22B has a metal material 226 that does not alloy with lithium in the gaps 224A and 224B. In this case, only one of the gaps 224A and 224B may have the metal material 226, but it is preferable that both have the metal material 226. This is because a higher effect can be obtained.

  The metal material 226 enters the gap 224A between the adjacent negative electrode active material particles 221. Specifically, when the negative electrode active material particles 221 are formed by a vapor phase method or the like, as described above, the negative electrode active material particles 221 grow for each protrusion existing on the surface of the negative electrode current collector 22A. A gap 224 </ b> A is generated between the adjacent negative electrode active material particles 221. Since the gap 224A causes a decrease in the binding property of the negative electrode active material layer 22B, the above-described gap 224A is filled with the metal material 226 in order to improve the binding property. In this case, it is sufficient that a part of the gap 224A is filled, but a larger filling amount is preferable. This is because the binding property of the negative electrode active material layer 22B is further improved. The filling amount of the metal material 226 is preferably 20% or more, more preferably 40% or more, and further preferably 80% or more.

  In addition, the metal material 226 enters the gap 224 </ b> B in the negative electrode active material particles 221. Specifically, when the negative electrode active material particles 221 have a multilayer structure, a gap 224B is generated between the layers. The gap 224B, like the gap 224A, causes a decrease in the binding property of the negative electrode active material layer 22B. Therefore, in order to increase the binding property, the gap 224B is filled with the metal material 226. ing. In this case, it is sufficient that a part of the gap 224B is filled, but a larger filling amount is preferable. This is because the binding property of the negative electrode active material layer 22B is further improved.

  Note that the negative electrode active material layer 22B is provided in order to prevent negative whisker-like protrusions (not shown) generated on the exposed surface of the uppermost negative electrode active material particles 221 from adversely affecting the performance of the secondary battery. A metal material 226 may be provided in the gap 225. Specifically, when the negative electrode active material particles 221 are formed by a vapor phase method or the like, fine whisker-like protrusions are formed on the surface thereof, and thus voids 225 are generated between the protrusions. This void 225 causes an increase in the surface area of the negative electrode active material particles 221 and also increases the amount of irreversible film formed on the surface, which causes a reduction in the degree of progress of the electrode reaction (charge / discharge reaction). there is a possibility. Therefore, the metal material 226 is embedded in the above-described gap 225 in order to suppress a decrease in the progress of the electrode reaction. In this case, it is sufficient that a part of the gap 225 is embedded, but it is preferable that the amount to be embedded is larger. This is because a decrease in the degree of progress of the electrode reaction is further suppressed. In FIG. 6, the fact that the metal material 226 is scattered on the surface of the uppermost negative electrode active material particle 221 indicates that the above-described fine protrusions are present at the spot. Of course, the metal material 226 does not necessarily have to be scattered on the surface of the negative electrode active material particle 221, and may cover the entire surface.

  In particular, the metal material 226 that has entered the gap 224B also functions to fill the gap 225 in each layer. Specifically, when the negative electrode material is deposited a plurality of times, the fine protrusions described above are generated on the surface of the negative electrode active material particles 221 every time the negative electrode material is deposited. From this, the metal material 226 not only fills the gap 224B in each layer, but also fills the gap 225 in each layer.

  5 and 6, the negative electrode active material particles 221 have a multilayer structure, and the case where both the gaps 224A and 224B exist in the negative electrode active material layer 22B has been described. 22B has a metal material 226 in the gaps 224A and 224B. On the other hand, when the negative electrode active material particle 221 has a single layer structure and only the gap 224A exists in the negative electrode active material layer 22B, the negative electrode active material layer 22B has the metal material 226 only in the gap 224A. It will have. Of course, since the gap 225 is generated in both cases, the gap 225 has the metal material 226 in either case.

  The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramic, and these two or more kinds of porous films are laminated. It may be what was done.

  The separator 23 is impregnated with the electrolytic solution described above. In this case, as described above, the content of the isocyanate compound shown in Chemical Formula 3 in the solvent is preferably 0.01% by weight or more and 5% by weight or less. This is because, regardless of the type of the negative electrode active material, the decomposition reaction of the electrolytic solution is suppressed and a high battery capacity can be obtained.

  However, the content of the isocyanate compound shown in Chemical Formula 3 in the solvent may vary depending on the type of the negative electrode active material. For example, when the negative electrode active material is a carbon material, it is preferable that the above-described content remains 0.01% by weight or more and 5% by weight or less. On the other hand, when the negative electrode active material is silicon or the like (a material that can occlude and release lithium and has at least one of a metal element and a metalloid element), the content described above is The content is preferably 0.01% by weight or more and 10% by weight or less.

  This secondary battery is manufactured, for example, by the following procedure.

  First, the positive electrode 21 is produced. First, a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent are mixed to form a positive electrode mixture, and then dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry is uniformly applied to both surfaces of the positive electrode current collector 21A by a doctor blade or a bar coater and dried. Finally, the positive electrode active material layer 21B is formed by compressing and molding the coating film with a roll press or the like while heating as necessary. In this case, compression molding may be repeated a plurality of times.

  Next, the negative electrode 22 is produced. First, after preparing a negative electrode current collector 22A made of electrolytic copper foil or the like, a plurality of negative electrode active material particles are formed by depositing a negative electrode material on both surfaces of the negative electrode current collector 22A by a vapor phase method such as a vapor deposition method. To do. After that, by forming an oxide-containing film by a liquid phase method such as a liquid phase deposition method, or by forming a metal material by a liquid phase method such as an electrolytic plating method, if necessary, The negative electrode active material layer 22B is formed.

  The secondary battery is assembled as follows. First, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Subsequently, after the positive electrode 21 and the negative electrode 22 are stacked and wound through the separator 23 to produce the wound electrode body 20, the center pin 24 is inserted into the winding center. Subsequently, the spirally wound electrode body 20 is housed in the battery can 11 while being sandwiched between the pair of insulating plates 12 and 13, the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tip of the negative electrode lead 26 is attached. Weld to battery can 11. Subsequently, the above-described electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. Finally, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by caulking through the gasket 17. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution impregnated in the separator 23. On the other hand, when discharging is performed, for example, lithium ions are released from the negative electrode 22 and inserted into the positive electrode 21 through the electrolytic solution impregnated in the separator 23.

  According to this cylindrical secondary battery, when the capacity of the negative electrode 22 is expressed based on insertion and extraction of lithium, the above-described electrolytic solution is provided, so that the chemical stability of the electrolytic solution is improved. To do. Thereby, since the decomposition reaction of the electrolytic solution is suppressed, cycle characteristics and storage characteristics can be improved.

  In particular, cycle characteristics and storage when the anode 22 contains silicon or the like (a material that can occlude and release lithium and has at least one of a metal element and a metalloid element) that is advantageous for increasing the capacity. Since the characteristics are improved, a higher effect can be obtained than when other negative electrode materials such as a carbon material are included.

(Secondary secondary battery)
The second secondary battery has the same configuration, operation, and effect as the first secondary battery except that the configuration of the negative electrode 22 is different, and is manufactured by the same procedure.

  The negative electrode 22 is provided with a negative electrode active material layer 22B on both surfaces of a negative electrode current collector 22A, as in the first secondary battery. The negative electrode active material layer 22B includes, for example, a material having silicon or tin as a constituent element as a negative electrode active material. Specifically, for example, a simple substance, an alloy or a compound of silicon, or a simple substance, an alloy or a compound of tin is included, and two or more kinds thereof may be included.

  The negative electrode active material layer 22B is formed by using a vapor phase method, a liquid phase method, a thermal spraying method, a firing method, or two or more of these methods. The negative electrode active material layer 22B and the negative electrode current collector It is preferable that 22A is alloyed in at least a part of the interface. Specifically, at the interface, the constituent elements of the negative electrode current collector 22A may diffuse into the negative electrode active material layer 22B, or the constituent elements of the negative electrode active material layer 22B diffuse into the negative electrode current collector 22A. Alternatively, the constituent elements of both may diffuse to each other. This is because, during charging / discharging, breakage due to expansion and contraction of the negative electrode active material layer 22B is suppressed, and electronic conductivity between the negative electrode active material layer 22B and the negative electrode current collector 22A is improved.

  As the vapor phase method, for example, physical deposition method or chemical deposition method, specifically, vacuum deposition method, sputtering method, ion plating method, laser ablation method, thermal chemical vapor deposition (CVD) Or plasma chemical vapor deposition. As the liquid phase method, a known method such as electroplating or electroless plating can be used. The firing method is, for example, a method in which a particulate negative electrode active material is mixed with a binder, dispersed in a solvent, applied, and then heat-treated at a temperature higher than the melting point of the binder. A known method can also be used for the firing method, for example, an atmospheric firing method, a reactive firing method, or a hot press firing method.

(Third secondary battery)
The third secondary battery is a lithium metal secondary battery in which the capacity of the negative electrode 22 is expressed based on precipitation and dissolution of lithium. This secondary battery has the same configuration as the first secondary battery except that the negative electrode active material layer 22B is made of lithium metal, and is manufactured by the same procedure.

  This secondary battery uses lithium metal as a negative electrode active material, and can thereby obtain a high energy density. The negative electrode active material layer 22B may already exist from the time of assembly, but may not be present at the time of assembly, and may be configured by lithium metal deposited during charging. Further, the negative electrode current collector 22A may be omitted by using the negative electrode active material layer 22B as a current collector.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and deposited as lithium metal on the surface of the negative electrode current collector 22A through the electrolytic solution impregnated in the separator 23. On the other hand, when discharging is performed, for example, lithium metal is eluted from the negative electrode active material layer 22 </ b> B as lithium ions and inserted into the positive electrode 21 through the electrolytic solution impregnated in the separator 23.

  According to this cylindrical secondary battery, when the capacity of the negative electrode 22 is expressed based on the precipitation and dissolution of lithium, the above-described electrolytic solution is provided, so that cycle characteristics and storage characteristics can be improved. it can. Other effects relating to the secondary battery are the same as those of the first secondary battery described above.

(Fourth secondary battery)
FIG. 7 shows an exploded perspective configuration of the fourth secondary battery, and FIG. 8 shows an enlarged cross section taken along line VIII-VIII of the spirally wound electrode body 30 shown in FIG.

  The secondary battery is, for example, a lithium ion secondary battery, similar to the first secondary battery described above, and the positive electrode lead 31 and the negative electrode lead 32 are mainly attached to the inside of the film-shaped exterior member 40. The wound electrode body 30 is accommodated. The battery structure using the film-shaped exterior member 40 is called a laminate film type.

  For example, the positive electrode lead 31 and the negative electrode lead 32 are led out in the same direction from the inside of the exterior member 40 toward the outside. The positive electrode lead 31 is made of, for example, a metal material such as aluminum, and the negative electrode lead 32 is made of, for example, a metal material such as copper, nickel, or stainless steel. These metal materials are, for example, in a thin plate shape or a mesh shape.

  The exterior member 40 is made of, for example, an aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. The exterior member 40 has a structure in which, for example, outer edges of two rectangular aluminum laminate films are bonded to each other by fusion or an adhesive so that the polyethylene film faces the wound electrode body 30. ing.

  An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32. Examples of such a material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

  In addition, the exterior member 40 may be constituted by a laminate film having another laminated structure instead of the above-described aluminum laminate film, or may be constituted by a polymer film such as polypropylene or a metal film.

  The electrode winding body 30 is wound after the positive electrode 33 and the negative electrode 34 are laminated via the separator 35 and the electrolyte 36, and the outermost periphery thereof is protected by a protective tape 37.

  In the positive electrode 33, for example, a positive electrode active material layer 33B is provided on both surfaces of a positive electrode current collector 33A. The negative electrode 34 is, for example, provided with a negative electrode active material layer 34B on both surfaces of a negative electrode current collector 34A, and the negative electrode active material layer 34B is disposed so as to face the positive electrode active material layer 33B. The configuration of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 is the same as that of the positive electrode current collector 21A and the positive electrode active material layer in the first secondary battery described above. The configurations of 21B, the negative electrode current collector 22A, the negative electrode active material layer 22B, and the separator 23 are the same.

  The electrolyte 36 is a so-called gel electrolyte that includes the above-described electrolytic solution and a polymer compound that holds the electrolytic solution. A gel electrolyte is preferable because high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained and liquid leakage is prevented.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and polyhexafluoropyrene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, poly Examples thereof include siloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate. These may be single and multiple types may be mixed. Among these, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene or polyethylene oxide is preferable. This is because it is electrochemically stable.

  In the electrolyte 36 which is a gel electrolyte, the solvent of the electrolytic solution is a wide concept including not only a liquid solvent but also an ion conductive substance capable of dissociating the electrolyte salt. Accordingly, when a polymer compound having ion conductivity is used, the polymer compound is also included in the solvent.

  Instead of the gel electrolyte 36 in which the electrolytic solution is held by the polymer compound, the electrolytic solution may be used as it is. In this case, the separator 35 is impregnated with the electrolytic solution.

  This secondary battery is manufactured by the following three types of manufacturing methods, for example.

  In the first manufacturing method, first, the positive electrode active material layer 33B is formed on both surfaces of the positive electrode current collector 33A, for example, by the same procedure as the positive electrode 21 and the negative electrode 22 in the first secondary battery described above. Thus, the negative electrode 34 is manufactured by forming the negative electrode active material layer 34B on both surfaces of the negative electrode current collector 34A. Then, after preparing the precursor solution containing electrolyte solution, a high molecular compound, and a solvent and apply | coating to the positive electrode 33 and the negative electrode 34, the solvent is volatilized and the gel electrolyte 36 is formed. Subsequently, the positive electrode lead 31 is attached to the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the negative electrode current collector 34A. Subsequently, the positive electrode 33 and the negative electrode 34 on which the electrolyte 36 is formed are stacked via the separator 35 and then wound in the longitudinal direction, and a protective tape 37 is adhered to the outermost peripheral portion thereof to produce the wound electrode body 30. To do. Finally, for example, after the wound electrode body 30 is sandwiched between two film-shaped exterior members 40, the outer edge portions of the exterior member 40 are bonded to each other by heat fusion or the like, so that the wound electrode body 30 is Encapsulate. At this time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the secondary battery shown in FIGS. 7 and 8 is completed.

  In the second manufacturing method, first, after attaching the positive electrode lead 31 to the positive electrode 33 and the negative electrode lead 32 to the negative electrode 34, the positive electrode 33 and the negative electrode 34 are stacked and wound via the separator 35. Then, a protective tape 37 is adhered to the outermost peripheral portion to produce a wound body that is a precursor of the wound electrode body 30. Subsequently, after sandwiching the wound body between the two film-shaped exterior members 40, the remaining outer peripheral edge except for the outer peripheral edge on one side is adhered by heat fusion or the like, thereby forming a bag-shaped exterior The wound body is accommodated in the member 40. Subsequently, an electrolyte composition containing an electrolytic solution, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary is prepared to form a bag-shaped exterior member. After injecting into the inside of 40, the opening part of the exterior member 40 is sealed by heat sealing or the like. Finally, the gel electrolyte 36 is formed by thermally polymerizing the monomer to obtain a polymer compound. Thereby, the secondary battery is completed.

  In the third manufacturing method, a wound body is formed by forming a wound body in the same manner as in the second manufacturing method described above except that the separator 35 coated with the polymer compound on both sides is used first. 40 is housed inside. Examples of the polymer compound applied to the separator 35 include a polymer containing vinylidene fluoride as a component, that is, a homopolymer, a copolymer, or a multi-component copolymer. Specifically, polyvinylidene fluoride, binary copolymers containing vinylidene fluoride and hexafluoropropylene as components, and ternary copolymers containing vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. Such as coalescence. In addition, the high molecular compound may contain the other 1 type, or 2 or more types of high molecular compound with the polymer which uses the above-mentioned vinylidene fluoride as a component. Subsequently, after the electrolytic solution is prepared and injected into the exterior member 40, the opening of the exterior member 40 is sealed by heat fusion or the like. Finally, the exterior member 40 is heated while applying a load, and the separator 35 is brought into close contact with the positive electrode 33 and the negative electrode 34 through the polymer compound. As a result, the electrolytic solution is impregnated into the polymer compound, and the polymer compound is gelled to form the electrolyte 36. Thus, the secondary battery is completed.

  In the third manufacturing method, the swollenness of the secondary battery is suppressed as compared with the first manufacturing method. Further, in the third manufacturing method, compared with the second manufacturing method, there are hardly any monomers or solvents that are raw materials for the polymer compound remaining in the electrolyte 36, and the formation process of the polymer compound is well controlled. Therefore, sufficient adhesion is obtained between the positive electrode 33, the negative electrode 34, the separator 35, and the electrolyte 36.

  According to this laminated film type secondary battery, when the capacity of the negative electrode 34 is expressed based on insertion and extraction of lithium, the above-described electrolytic solution is provided, so that the same as the first secondary battery. , Cycle characteristics and storage characteristics can be improved. The effects of the secondary battery other than those described above are the same as those of the first secondary battery.

  Of course, the laminated film type secondary battery is not limited to the same configuration as the first secondary battery, and may have the same configuration as the second or third secondary battery.

  Specific examples of the present invention will be described in detail.

(Example 1-1)
By using silicon, which is a material capable of inserting and extracting lithium as a negative electrode active material and having at least one of a metal element and a metalloid element, the following steps are used. The shown laminate film type secondary battery was produced. At this time, a lithium ion secondary battery in which the capacity of the negative electrode 34 is expressed based on insertion and extraction of lithium was made.

First, the positive electrode 33 was produced. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of 0.5: 1, and then calcined in air at 900 ° C. for 5 hours to form a lithium cobalt composite. An oxide (LiCoO ₂ ) was obtained. Subsequently, after mixing 91 parts by mass of lithium cobalt composite oxide as the positive electrode active material, 3 parts by mass of polyvinylidene fluoride as the positive electrode binder, and 6 parts by mass of graphite as the positive electrode conductive agent, a positive electrode mixture was obtained. Dispersed in N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry was uniformly applied to both surfaces of the positive electrode current collector 33A made of a strip-shaped aluminum foil (thickness = 12 μm) by a bar coater, dried, and then compression-molded by a roll press to perform positive electrode activation. A material layer 33B was formed.

  Next, after preparing a negative electrode current collector 34A (thickness = 15 μm) made of a roughened electrolytic copper foil, silicon is deposited as a negative electrode active material on both surfaces of the negative electrode current collector 34A by an electron beam evaporation method. The negative electrode 34 was produced by forming the negative electrode active material layer 34B. In the case of forming this negative electrode active material layer 34B, the negative electrode active material particles were formed through 10 deposition steps so that the negative electrode active material particles had a 10-layer structure. At this time, the thickness (total thickness) of the negative electrode active material particles on one side of the negative electrode current collector 34A was 6 μm.

Next, an electrolytic solution was prepared. First, after mixing ethylene carbonate (EC) and diethyl carbonate (DEC), the compound of Chemical Formula 11 (1), which is the isocyanate compound shown in Chemical Formula 3, was added to prepare a solvent. At this time, the composition of the solvent (EC: DEC) was 30:70 by weight, and the content of the compound of Chemical Formula 11 (1) in the solvent was 0.01% by weight. The content (% by weight) of the compound of the chemical formula 11 (1) is a ratio when the total sum of the solvents (EC + DEC + compound of the chemical formula 11 (1)) is 100% by weight. After that, lithium hexafluorophosphate (LiPF ₆ ) was dissolved in the solvent as an electrolyte salt. At this time, the content of lithium hexafluorophosphate was 1 mol / kg with respect to the solvent.

  Finally, a secondary battery was assembled using the electrolytic solution together with the positive electrode 33 and the negative electrode 34. First, the positive electrode lead 31 made of aluminum was welded to one end of the positive electrode current collector 33A, and the negative electrode lead 32 made of nickel was welded to one end of the negative electrode current collector 34A. Subsequently, after laminating and winding the positive electrode 33, the separator 35 (thickness = 25 μm) made of a microporous polypropylene film, and the negative electrode 54, the winding end portion is fixed with a protective tape 37 made of an adhesive tape. Thus, a wound body that is a precursor of the wound electrode body 30 was formed. Subsequently, a laminate film (total thickness) in which a nylon film (thickness = 30 μm), an aluminum foil (thickness = 40 μm), and an unstretched polypropylene film (thickness = 30 μm) are laminated from the outside. = 100 μm), the wound body was sandwiched between the exterior members 40, and the outer edges except for one side were heat-sealed to accommodate the wound body inside the bag-shaped exterior member 40. Subsequently, an electrolytic solution was injected from the opening of the exterior member 40 and impregnated in the separator 35 to produce the wound electrode body 30. Finally, the laminated film type secondary battery was completed by thermally sealing and sealing the opening of the exterior member 40 in a vacuum atmosphere. For this secondary battery, the thickness of the positive electrode active material layer 33B was adjusted so that lithium metal did not deposit on the negative electrode 34 during full charge.

(Examples 1-2 to 1-7)
The content of the compound of Chemical Formula 11 (1) was 1 wt% (Example 1-2), 2 wt% (Example 1-3), 3 wt% (Example 1-4), 5 wt% (Example) 1-5) A procedure similar to that of Example 1-1 was performed, except that the content was 10% by weight (Example 1-6) or 12% by weight (Example 1-7).

(Example 1-8)
The same procedure as in Example 1-4 was performed, except that the compound of Chemical Formula 11 (2) was used in place of the compound of Chemical Formula 11 (1) as the isocyanate compound shown in Chemical Formula 3.

(Comparative Example 1-1)
The same procedure as in Example 1-1 was performed except that the compound of Chemical Formula 11 (1) was not contained.

(Comparative Example 1-2)
A procedure similar to that in Example 1-4 was performed, except that the compound of Chemical formula 29 was contained instead of the compound of Chemical formula 11 (1).

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 1-1 to 1-8 and Comparative examples 1-1 and 1-2 were examined, the results shown in Table 1 were obtained.

  When examining the cycle characteristics, first, charging and discharging were performed for 2 cycles in an atmosphere at 23 ° C., and the discharge capacity at the second cycle was measured. Subsequently, the battery was repeatedly charged and discharged in the same atmosphere until the total number of cycles reached 100 cycles, and the discharge capacity at the 100th cycle was measured. Finally, room temperature cycle discharge capacity retention ratio (%) = (discharge capacity at the 100th cycle / discharge capacity at the second cycle) × 100 was calculated. As charging / discharging conditions, constant current and constant voltage charging was performed up to an upper limit voltage of 4.2 V at a current of 0.2 C, and then constant current discharging was performed up to a final voltage of 2.7 V at a current of 0.2 C. This “0.2 C” is a current value at which the theoretical capacity can be discharged in 5 hours.

  When examining the storage characteristics, first, charging and discharging were performed for 2 cycles in an atmosphere at 23 ° C., and the discharge capacity before storage was measured. Subsequently, the battery was stored again in a constant temperature bath at 80 ° C. for 10 days while being charged again, and then discharged in an atmosphere at 23 ° C., and the discharge capacity after storage was measured. Finally, high temperature storage discharge capacity retention rate (%) = (discharge capacity after storage / discharge capacity before storage) × 100 was calculated. The charge / discharge conditions were the same as when the cycle characteristics were examined.

  The procedures and conditions for examining the cycle characteristics and storage characteristics described above are the same for the series of examples and comparative examples described below.

  As shown in Table 1, in the case of using silicon as the negative electrode active material, in Examples 1-1 to 1-8 in which the solvent of the electrolytic solution contains the compound of Chemical Formula 11 (1), (2), Compared with Comparative Examples 1-1 and 1-2 not containing it, a high normal temperature cycle discharge capacity retention ratio and a high temperature storage discharge capacity retention ratio were obtained.

  Specifically, in Examples 1-1 to 1-7 containing the compound of Chemical Formula 11 (1), the room temperature cycle discharge capacity retention rate was not dependent on the content and compared with Comparative Example 1-1. And the high-temperature storage discharge maintenance rate became high. In this case, when the content of the compound of chemical formula 11 (1) in the solvent is 0.01 wt% or more and 12 wt% or less, a high normal temperature cycle discharge capacity maintenance ratio and a high temperature storage discharge capacity maintenance ratio can be obtained. It was. When the content of the compound of formula 11 (1) is less than 0.01% by weight, the room temperature cycle discharge capacity maintenance rate and the high-temperature storage discharge capacity maintenance rate are not sufficiently high, and are greater than 10% by weight. In addition, a high normal temperature cycle discharge capacity retention ratio and a high temperature storage discharge capacity retention ratio were obtained, while the battery capacity was apt to decrease.

  Moreover, in Example 1-8 containing the compound of Chemical Formula 11 (2), as in Example 1-4 containing the compound of Chemical Formula 11 (1), compared with Comparative Example 1-1, the normal temperature cycle The discharge capacity maintenance rate and the high temperature storage discharge capacity maintenance rate increased. In Examples 1-4 and 1-8, the normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate were substantially the same.

  Furthermore, in Comparative Example 1-2 containing the compound of Chemical Formula 29, the normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate were higher than those in Comparative Example 1-1 not containing the compound. However, the normal temperature cycle discharge capacity retention ratio and the high temperature storage discharge capacity retention ratio obtained in Comparative Example 1-2 are the normal temperature cycle discharge capacity retention ratios obtained in Example 1-4 containing the compound of Chemical formula 11 (1). Rate and high temperature storage discharge capacity maintenance rate. As a result, in order to improve the normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate, the site where the isocyanate group and the electron withdrawing group (carbonyl group) are bonded, compared to the case where only the isocyanate group is included. It is advantageous in the case of having

  From these facts, in the secondary battery of the present invention, when the negative electrode 34 contains silicon as the negative electrode active material, the electrolyte solution contains the isocyanate compound shown in Chemical Formula 3 so that the cycle characteristics and the storage characteristics are improved. It was confirmed to improve. In this case, it is also confirmed that excellent battery capacity, cycle characteristics and storage characteristics can be obtained if the content of the isocyanate compound shown in Chemical Formula 3 in the solvent is 0.01 wt% or more and 10 wt% or less. It was.

(Examples 2-1 and 2-2)
A procedure similar to that of Example 1-4 was performed except that dimethyl carbonate (DMC: Example 2-1) or ethyl methyl carbonate (EMC: Example 2-2) was used instead of DEC as a solvent.

(Example 2-3)
Propyl carbonate (PC) was added as a solvent, and the same procedure as in Example 1-4 was performed, except that the solvent composition (EC: DEC: PC) was 10:70:20 by weight.

(Examples 2-4 to 2-7)
As a solvent, bis (fluoromethyl) carbonate (DFDMC) (Example 2-4) which is a chain carbonate having a halogen shown in Chemical Formula 12 or 4-cyclic carbonate having a halogen shown in Chemical Formula 13 is used. Fluoro-1,3-dioxolan-2-one (FEC: Example 2-5) or trans-4,5-difluoro-1,3-dioxolan-2-one (t-DFEC: Example 2-6), Alternatively, the same procedure as in Example 1-4 was performed, except that vinylene carbonate (VC: Example 2-7), which is a cyclic carbonate having an unsaturated bond shown in Chemical Formula 16, was added. At this time, the addition amount of DFDMC and the like in the solvent was 5% by weight.

(Comparative Examples 2-1 to 2-3)
The same procedure as in Examples 2-5 to 2-7 was performed except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 2-1 to 2-7 and Comparative Examples 2-1 to 2-3 were examined, the results shown in Table 2 were obtained.

  As shown in Table 2, also in Examples 2-1 to 2-7 in which the composition of the solvent was changed, similarly to Example 1-4, compared with Comparative Example 1-1, the room temperature cycle discharge capacity was high. A maintenance rate and a high temperature storage discharge capacity maintenance rate were obtained. Of course, when the solvent contains FEC or the like, in Examples 2-5 to 2-7, compared with Comparative Examples 2-1 to 2-3, a higher room temperature cycle discharge capacity retention rate and high-temperature storage discharge capacity A retention rate was obtained.

  In particular, in Examples 2-1 to 2-3 in which DEC is changed to DMC or the like, or PC is added, a room temperature cycle discharge capacity maintenance rate and a high-temperature storage discharge capacity maintenance rate almost the same as those in Example 1-4 are obtained. It was.

  Moreover, in Examples 2-4 to 2-7 using FEC or the like, the room temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate were higher than those in Example 1-4. In this case, as apparent from the comparison between Examples 2-5 and 2-6, when the number of halogens increased, the normal temperature cycle discharge capacity retention rate and the high temperature storage discharge capacity retention rate tended to be higher. .

  In this case, a chain carbonate having a halogen shown in Chemical formula 12, a cyclic carbonate having a halogen shown in Chemical formula 13, and a cyclic carbonate having an unsaturated bond shown in Chemical formula 16 are used as a solvent. Only the results are shown, and the results in the case of using the cyclic carbonate having an unsaturated bond shown in Chemical Formula 17 or Chemical Formula 18 are not shown. However, the cyclic carbonate having an unsaturated bond shown in Chemical formula 17 increases the normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity maintenance rate in the same manner as the cyclic carbonate ester having an unsaturated bond shown in Chemical formula 16. In order to fulfill the function, it is clear that the same result can be obtained when the former is used as when the latter is used.

  From these, it was confirmed that in the secondary battery of the present invention in which the negative electrode 34 contains silicon as the negative electrode active material, the cycle characteristics and the storage characteristics are improved even if the composition of the solvent is changed. In this case, as the solvent, a chain carbonate having a halogen shown in Chemical formula 12, a cyclic carbonate having a halogen shown in Chemical formula 13, or a cyclic carbonate having an unsaturated bond shown in Chemical formulas 16 to 18 is used. It was also confirmed that the characteristics were further improved by using. In addition, when the chain carbonate having halogen shown in Chemical formula 12 or the cyclic carbonate having halogen shown in Chemical formula 13 was used, it was confirmed that the characteristics were further improved as the number of halogens increased. .

(Examples 3-1 to 3-3)
As an electrolyte salt, lithium tetrafluoroborate (LiBF ₄ : Example 3-1), a compound of Chemical Formula 22 (6) (Example 3-2) which is a compound shown in Chemical Formula 19, or a chemical formula 25 The same procedure as in Example 1-4 was performed, except that the compound bis (trifluoromethanesulfonyl) imidolithium (LiTFSI: Example 3-3) was added. At this time, the content of lithium hexafluorophosphate was 0.9 mol / kg with respect to the solvent, and the content of lithium tetrafluoroborate and the like was 0.1 mol / kg with respect to the solvent.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 3-1 to 3-3 were examined, the results shown in Table 3 were obtained.

  As shown in Table 3, in Examples 3-1 to 3-3 in which the electrolyte salt contains lithium tetrafluoroborate or the like, the room temperature is equal to or higher than that of Example 1-4 that does not contain them. A cycle discharge capacity retention ratio and a high temperature storage discharge capacity retention ratio were obtained.

  Specifically, in Example 3-1, which contains lithium tetrafluoroborate, the room temperature cycle discharge capacity retention rate is equivalent and the high-temperature storage discharge capacity retention rate is higher than in Example 1-4. It was. Further, in Examples 3-2 and 3-3 containing the compound of Chemical Formula 22 (6) and the like, both the room temperature cycle discharge capacity maintenance rate and the high temperature storage discharge capacity maintenance rate were both compared to Example 1-4. It became high.

  Here, only the results obtained when lithium tetrafluoroborate or a compound shown in Chemical Formula 19 or Chemical Formula 25 is used as the electrolyte salt are shown, and lithium perchlorate, lithium hexafluoroarsenate, or The results when using the compounds shown in Chemical Formula 20, Chemical Formula 21, Chemical Formula 26 or Chemical Formula 27 are not shown. However, lithium perchlorate and the like, like lithium tetrafluoroborate, have the function of increasing the normal temperature cycle discharge capacity maintenance rate and the high-temperature storage discharge capacity maintenance rate, so the latter is used even when the former is used. It is clear that the same results as those obtained were obtained.

  From these results, it was confirmed that in the secondary battery of the present invention in which the negative electrode 34 contains silicon as the negative electrode active material, the cycle characteristics and the storage characteristics are improved even if the type of the electrolyte salt is changed. In this case, characteristics can be obtained by using lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, or the compounds shown in Chemical Formulas 19 to 21 or Chemicals 25 to 27 as the electrolyte salt. It was also confirmed that it improved further.

(Example 4-1)
The same procedure as in Example 1-1 was performed except that the negative electrode active material layer 34B was formed using artificial graphite, which is a carbon material, instead of silicon as the negative electrode active material. When forming this negative electrode active material layer 34B, a negative electrode mixture in which 90 parts by mass of artificial graphite as a negative electrode active material and 10 parts by mass of polyvinylidene fluoride as a negative electrode binder is mixed is N-methyl-2-pyrrolidone. The paste was mixed into a paste-like positive electrode mixture slurry, and the negative electrode mixture slurry was uniformly applied to both sides of the negative electrode current collector 34A made of a strip-like electrolytic copper foil (thickness = 15 μm) by a bar coater and dried. Compressed with a roll press. At this time, the thickness of the negative electrode active material layer 34B on one side of the negative electrode current collector 34A was set to 75 μm.

(Examples 4-2 to 4-6)
The content of the compound of Chemical Formula 11 (1) was 0.5 wt% (Example 4-2), 1 wt% (Example 4-3), 2 wt% (Example 4-4), 5 wt% ( The same procedure as in Example 4-1 was performed except that Example 4-5) or 10% by weight (Example 4-6) was used.

(Example 4-7)
The same procedure as in Example 4-3 was performed, except that the compound of Chemical Formula 11 (2) was used in place of the compound of Chemical Formula 11 (1) as the isocyanate compound shown in Chemical Formula 3.

(Comparative Example 3)
The same procedure as in Example 4-1 was performed, except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 4-1 to 4-7 and Comparative Example 3 were examined, the results shown in Table 4 were obtained.

  As shown in Table 4, when artificial graphite was used as the negative electrode active material, the same results as those shown in Table 1 were obtained. That is, in Examples 4-1 to 4-8 in which the solvent of the electrolytic solution contains the compounds of Chemical Formulas 11 (1) and (2), a higher room temperature cycle discharge capacity is maintained as compared with Comparative Example 3 that does not contain them. Rate and high temperature storage discharge capacity retention rate were obtained. In this case, when the content of the compound of chemical formula 11 (1) in the solvent is 0.01 wt% or more and 10 wt% or more, a high normal temperature cycle discharge capacity maintenance ratio and a high temperature storage discharge capacity maintenance ratio can be obtained. When the content was 0.01 wt% or more and 5 wt% or less, a high battery capacity was also obtained.

  From these facts, in the secondary battery of the present invention, when the negative electrode 34 contains artificial graphite as the negative electrode active material, the electrolyte solution contains the isocyanate compound shown in Chemical Formula 3 so that cycle characteristics and storage characteristics are obtained. Has been confirmed to improve. In this case, it is also confirmed that excellent battery capacity, cycle characteristics and storage characteristics can be obtained if the content of the isocyanate compound shown in Chemical Formula 3 in the solvent is 0.01 wt% or more and 5 wt% or less. It was.

  From the results shown in Table 1 and Table 4, if the content of the isocyanate compound shown in Chemical Formula 3 in the solvent is 0.01 wt% or more and 5 wt% or less, the type of the negative electrode active material (silicon or artificial graphite) It is derived that excellent battery capacity, cycle characteristics, and storage characteristics can be obtained without depending on.

(Examples 5-1 and 5-2)
A procedure similar to that in Example 4-3 was performed except that DMC (Example 5-1) or EMC (Example 5-2) was used instead of DEC as a solvent.

(Example 5-3)
PC was added as a solvent, and the same procedure as in Example 4-3 was performed except that the composition of the solvent (EC: DEC: PC) was 10:70:20 by weight.

(Examples 5-4 to 5-7)
Example 4 except that DFDMC (Example 5-4), FEC (Example 5-5), DFEC (Example 5-6), or VC (Example 5-7) was added as a solvent. The same procedure as 3 was performed. At this time, the amount of DFDMC and the like added in the solvent was 2% by weight.

(Comparative Examples 4-1 to 4-3)
The same procedure as in Examples 5-5 to 5-7 was performed, except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 5-1 to 5-7 and Comparative examples 4-1 to 4-3 were examined, the results shown in Table 5 were obtained.

  As shown in Table 5, when artificial graphite was used as the negative electrode active material, the same results as those shown in Table 2 were obtained. That is, in Examples 5-1 to 5-7 in which the composition of the solvent was changed, as in Example 4-3, compared with Comparative Examples 3, 4-1 to 4-3, a high room temperature cycle discharge capacity was maintained. Rate and high temperature storage discharge capacity retention rate were obtained. In particular, in Examples 5-1 to 5-3 in which DEC was changed to DMC or the like, or PC was added, the room temperature cycle discharge capacity maintenance rate and the high-temperature storage discharge capacity maintenance rate were higher than in Example 4-3. . In Examples 5-4 to 5-7 using FEC or the like, the normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate were higher than those in Example 4-3.

  From these results, it was confirmed that in the secondary battery of the present invention in which the negative electrode 34 includes artificial graphite as the negative electrode active material, the cycle characteristics and the storage characteristics are improved even when the composition of the solvent is changed. In this case, as the solvent, a chain carbonate having a halogen shown in Chemical formula 12, a cyclic carbonate having a halogen shown in Chemical formula 13, or a cyclic carbonate having an unsaturated bond shown in Chemical formulas 16 to 18 is used. It was also confirmed that the characteristics were further improved by using.

(Examples 6-1 to 6-3)
Example 4-3 except that LiBF ₄ (Example 6-1), the compound of Chemical Formula 22 (6) (Example 6-2), or LiTFSI (Example 6-3) was added as an electrolyte salt. The same procedure was followed. At this time, the content of lithium hexafluorophosphate was 0.9 mol / kg with respect to the solvent, and the content of lithium tetrafluoroborate and the like was 0.1 mol / kg with respect to the solvent.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 6-1 to 6-3 were examined, the results shown in Table 6 were obtained.

  As shown in Table 6, even when artificial graphite was used as the negative electrode active material, the same results as those shown in Table 3 were obtained. That is, in Examples 6-1 to 6-3 in which the electrolyte salt contains lithium tetrafluoroborate or the like, compared with Example 4-3 not containing them, the room temperature cycle discharge capacity maintenance rate equal to or higher than that and A high temperature storage discharge capacity retention rate was obtained.

  From these facts, it was confirmed that in the secondary battery of the present invention in which the negative electrode 34 includes artificial graphite as the negative electrode active material, the cycle characteristics and the storage characteristics are improved even if the type of the electrolyte salt is changed. In this case, if the electrolyte salt is lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, or a compound shown in Chemical formula 19 to Chemical formula 21 or Chemical formula 25 to Chemical formula 27, the characteristics are further improved. It was also confirmed that it improved.

(Example 7-1)
As the negative electrode active material, a negative electrode active material can be used by using SnCoC-containing material, which is a material that can occlude and release lithium in the same way as silicon and has at least one of a metal element and a metalloid element. The same procedure as in Example 1-4 was performed except that the material layer 34B was formed.

  In forming this negative electrode active material layer 34B, first, cobalt powder and tin powder were alloyed to form cobalt-tin alloy powder, and then carbon powder was added and dry mixed. Subsequently, 10 g of the above mixture was set together with about 400 g of steel balls having a diameter of 9 mm in a reaction vessel of a planetary ball mill manufactured by Ito Seisakusho. Subsequently, after replacing the inside of the reaction vessel with an argon atmosphere, an operation for 10 minutes and a pause for 10 minutes at a rotation speed of 250 revolutions per minute were repeated until the total operation time reached 20 hours. Subsequently, after the reaction vessel was cooled to room temperature and the SnCoC-containing material was taken out, the coarse powder was removed through a 280 mesh sieve.

  When the composition of the obtained SnCoC-containing material was analyzed, the content of tin was 49.5% by mass, the content of cobalt was 29.7% by mass, the content of carbon was 19.8% by mass, tin and cobalt The ratio of cobalt to the total of (Co / (Sn + Co)) was 37.5% by mass. At this time, the tin and cobalt contents were measured by inductively coupled plasma (ICP) emission analysis, and the carbon content was measured by a carbon / sulfur analyzer. Further, when the SnCoC-containing material was analyzed by the X-ray diffraction method, a diffraction peak having a half width in the range of 2θ = 20 ° to 50 ° was observed. Further, when the SnCoC-containing material was analyzed by XPS, a peak P1 was obtained as shown in FIG. When this peak P1 was analyzed, a peak P2 of surface contamination carbon and a peak P3 of C1s in the SnCoC-containing material on the lower energy side (region lower than 284.5 eV) were obtained. From this result, it was confirmed that carbon in the SnCoC-containing material was bonded to other elements.

  After obtaining the SnCoC-containing material, 80 parts by mass of the SnCoC-containing material as the negative electrode active material, 8 parts by mass of polyvinylidene fluoride as the negative electrode binder, 11 parts by mass of graphite and 1 part by mass of acetylene black as the negative electrode conductive agent are mixed After preparing a negative electrode mixture, it was dispersed in N-methyl-2-pyrrolidone to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry was uniformly applied to both surfaces of the negative electrode current collector 34A made of a strip-shaped electrolytic copper foil (thickness = 15 μm) with a bar coater, dried, and then compressed with a roll press. Molded. At this time, the thickness of the negative electrode active material layer 34B on one side of the negative electrode current collector 34A was set to 50 μm.

(Example 7-2)
The same procedure as in Example 7-1 was performed except that FEC was added as a solvent. At this time, the content of FEC in the solvent was 5% by weight.

(Comparative Examples 5-1 and 5-2)
The same procedure as in Examples 7-1 and 7-2 was performed except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Examples 7-1 and 7-2 and Comparative Examples 5-1 and 5-2 were examined, the results shown in Table 7 were obtained.

  As shown in Table 7, even when the SnCoC-containing material was used as the negative electrode active material, the same results as those shown in Table 1 and Table 2 were obtained. That is, in Examples 7-1 and 7-2 in which the solvent of the electrolytic solution contains the compound of Chemical Formula 11 (1), compared with Comparative Examples 7-1 and 7-2 that do not contain the compound, higher room temperature cycle discharge A capacity retention ratio and a high temperature storage discharge capacity retention ratio were obtained. Moreover, in Example 7-2 in which the solvent contains FEC, the room temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate were higher than those in Example 7-1 that did not contain FEC.

  From these facts, in the secondary battery of the present invention, when the negative electrode 34 contains a SnCoC-containing material as the negative electrode active material, the solvent of the electrolyte solution contains the isocyanate compound shown in Chemical Formula 3 so that cycle characteristics and storage can be achieved. It was confirmed that the characteristics were improved.

(Example 8)
When forming the negative electrode active material layer 34B, after forming a plurality of negative electrode active material particles, a silicon oxide (SiO ₂ ) is deposited as an oxide-containing film on the surface of the negative electrode active material particles by a liquid phase deposition method. Except that, the same procedure as in Example 1-4 was performed. In the case of forming this oxide-containing film, the negative electrode current collector 34A in which the negative electrode active material particles are formed is immersed for 3 hours in a solution in which boron is dissolved as an anion scavenger in hydrofluoric acid, After depositing silicon oxide on the surface of the negative electrode active material particles, it was washed with water and dried under reduced pressure.

(Comparative Example 6)
The same procedure as in Example 8 was performed, except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Example 8 and Comparative Example 6 were examined, the results shown in Table 8 were obtained.

  As shown in Table 8, when the oxide-containing film was formed, the same result as that shown in Table 1 was obtained. That is, in Example 8 in which the solvent contains the compound of Chemical Formula 11 (1), the high normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate are higher than those in Comparative Examples 1-1 and 6 that do not contain the compound. Obtained.

  In particular, in Example 8 in which the oxide-containing film was formed, the room temperature cycle discharge maintenance rate and the high-temperature storage discharge capacity maintenance rate were higher than those in Example 1-4 in which the oxide-containing film was not formed.

  Here, only the result when a silicon oxide is formed as the oxide-containing film is shown, and the result when a germanium or tin oxide is formed is not shown. However, germanium and other oxides, like the silicon oxide, have the function of increasing the normal temperature cycle discharge capacity retention rate and the high temperature storage discharge capacity retention rate. It is clear that similar results are obtained.

  For these reasons, in the secondary battery of the present invention, when the electrolyte solution contains the isocyanate compound shown in Chemical Formula 3, even when an oxide-containing film is formed, cycle characteristics and storage characteristics are improved. It was confirmed. In this case, it was also confirmed that the characteristics were further improved by forming an oxide-containing film.

Example 9
In the case of forming the negative electrode active material layer 34B, Example 1-4 and Example 1-4 except that after forming a plurality of negative electrode active material particles, a plating film of cobalt (Co) was grown as a metal material by an electrolytic plating method. A similar procedure was followed. In the case of forming this metal material, current was supplied while supplying air to the plating bath, and cobalt was deposited on both surfaces of the negative electrode current collector 34A. At this time, a cobalt plating solution manufactured by Japan High Purity Chemical Co., Ltd. was used as the plating solution, the current density was 2 A / dm ^{2 to} 5 A / dm ² , and the plating rate was 10 nm / second.

(Comparative Example 7)
The same procedure as in Example 9 was performed, except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics and the storage characteristics of the secondary batteries of Example 9 and Comparative Example 7 were examined, the results shown in Table 9 were obtained.

  As shown in Table 9, when the metal material was formed, the same result as that shown in Table 1 was obtained. That is, in Example 9 in which the solvent contains the compound of Chemical Formula 11 (1), compared with Comparative Examples 1-1 and 7 that do not contain the compound, the high normal temperature cycle discharge capacity retention rate and the high-temperature storage discharge capacity retention rate are high. Obtained.

  In particular, in Example 9 in which the metal material was formed, the room temperature cycle discharge maintenance rate and the high-temperature storage discharge capacity maintenance rate were higher than those in Example 1-4 in which the metal material was not formed.

  Here, only the result when a cobalt plating film is formed as a metal material is shown, and the result when an iron, nickel, zinc, or copper plating film is formed is not shown. However, since the plating film of iron or the like functions to increase the normal temperature cycle discharge capacity maintenance rate and the high-temperature storage discharge capacity maintenance rate in the same manner as the cobalt plating film, the case of using the former and the case of using the latter It is clear that similar results are obtained.

  From these facts, in the secondary battery of the present invention, when the electrolyte solution contains the isocyanate compound shown in Chemical Formula 3, even when a metal material is formed, cycle characteristics and storage characteristics can be improved. confirmed. In this case, it was also confirmed that the characteristics were further improved by forming a metal material.

(Examples 10-1 to 10-3)
In the case of forming the negative electrode active material layer 34B, Example 1- except that the oxide-containing film and the metal material were formed in this order by the procedures of Examples 8 and 9 after forming a plurality of negative electrode active material particles. The same procedure as 4, 2-5, 2-6 was performed.

(Comparative Examples 8-1 to 8-3)
The same procedure as in Examples 10-1 to 10-3 was performed except that the compound of Chemical Formula 11 (1) was not contained.

  When the cycle characteristics of the secondary batteries of Examples 10-1 to 10-3 and Comparative examples 8-1 to 8-3 were examined, the results shown in Table 10 were obtained.

  As shown in Table 10, when both the oxide-containing film and the metal material were formed, the same results as those shown in Table 1 and Table 2 were obtained. That is, in Examples 10-1 to 10-3 in which the solvent contains the compound of Chemical Formula 11 (1), as in Example 1-4, Comparative Examples 1-1 and 8-1 to 8- Compared with 3, high room temperature cycle discharge capacity retention ratio and high temperature storage discharge capacity retention ratio were obtained. Moreover, in Examples 10-2 and 10-3 in which the solvent contains FEC and DFEC, compared with Examples 1-4 and 10-1 that do not contain them, a high room temperature cycle discharge capacity retention rate and high-temperature storage discharge A capacity retention rate was obtained.

  In particular, in Example 10-1 in which both the oxide-containing film and the metal material were formed, compared with Example 8 in which only the oxide-containing film was formed and Example 9 in which only the metal material was formed, the room temperature cycle. The discharge capacity maintenance rate and the high temperature storage discharge capacity maintenance rate increased.

  From these facts, in the secondary battery of the present invention, even when both the oxide-containing film and the metal material are formed by containing the isocyanate compound shown in Chemical Formula 3 as the solvent of the electrolytic solution, the cycle characteristics and It was confirmed that the storage characteristics were improved. In this case, it was also confirmed that the characteristics were further improved by forming both the oxide-containing film and the metal material.

  From the results shown in Tables 1 to 10, in the secondary battery of the present invention, the solvent of the electrolytic solution contains the isocyanate compound shown in Chemical Formula 3, so that it depends on the type of the negative electrode active material and the composition of the solvent. It was confirmed that the cycle characteristics and the storage characteristics were improved.

  In this case, as a negative electrode active material, a material that can occlude and release lithium and has at least one of a metal element and a metalloid element as compared with the case where a carbon material (artificial graphite) is used. In the case of using (silicon or SnCoC-containing material), the increase rate of the discharge capacity retention rate was increased, and it was also confirmed that a higher effect was obtained in the latter case than in the former case. This result suggests that the use of silicon, which is advantageous for increasing the capacity as the negative electrode active material, makes the electrolyte solution more easily decomposed than when a carbon material is used. It is done.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the embodiments described in the above embodiments and examples, and various modifications can be made. For example, the usage application of the electrolytic solution of the present invention is not necessarily limited to a secondary battery, but may be an electrochemical device other than the secondary battery. Other applications include, for example, capacitors.

  In the above-described embodiments and examples, the types of secondary batteries include lithium ion secondary batteries in which the negative electrode capacity is expressed based on insertion and extraction of lithium, and the negative electrode capacity is lithium deposition and dissolution. Although the lithium metal secondary battery expressed based on the above has been described, the present invention is not necessarily limited thereto. The secondary battery of the present invention uses a material capable of inserting and extracting lithium as the negative electrode active material, and the chargeable capacity of the negative electrode material capable of inserting and extracting lithium is higher than the discharge capacity of the positive electrode. The same applies to secondary batteries in which the capacity of the negative electrode includes the capacity associated with insertion and extraction of lithium and the capacity associated with precipitation and dissolution of lithium, and is expressed by the sum of these capacities. Is possible.

  In the above-described embodiments and examples, the case where the electrolytic solution or the gel electrolyte in which the electrolytic solution is held in the polymer compound is used as the electrolyte of the secondary battery of the present invention has been described. The electrolyte may be used. Other electrolytes include, for example, a mixture of an ion conductive inorganic compound such as ion conductive ceramics, ion conductive glass or ionic crystal and an electrolyte, or a mixture of another inorganic compound and an electrolyte. Or a mixture of these inorganic compounds and a gel electrolyte.

  In the above-described embodiments and examples, the case where the battery structure is a cylindrical type and a laminate film type and the case where the battery element has a winding structure have been described as examples. However, the secondary battery of the present invention is described. Can be similarly applied to cases where other battery structures such as a square shape, a coin shape, and a button shape are provided, and where battery elements have other structures such as a laminated structure.

  In the above-described embodiments and examples, the case where lithium is used as the electrode reactant has been described. However, other group 1 elements such as sodium (Na) or potassium (K), magnesium (Mg) or calcium ( Group 2 elements such as Ca) or other light metals such as aluminum may be used. Also in these cases, the negative electrode material described in the above embodiment can be used as the negative electrode active material.

  Moreover, although the said embodiment and Example demonstrate the appropriate range derived | led-out from the result of the Example about content of the isocyanate compound shown to Chemical formula 3 in the electrolyte solution or secondary battery of this invention, The explanation does not completely deny the possibility that the content is outside the above range. In other words, the appropriate range described above is a particularly preferable range for obtaining the effect of the present invention, and the content may be slightly deviated from the above range as long as the effect of the present invention is obtained.

It is sectional drawing showing the structure of the 1st secondary battery provided with the electrolyte solution which concerns on one embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. FIG. 3 is an enlarged cross-sectional view illustrating a configuration of a negative electrode illustrated in FIG. 2. It is sectional drawing showing the structure of the negative electrode of a reference example. FIG. 3 is an SEM photograph showing a cross-sectional structure of the negative electrode shown in FIG. 2 and a schematic diagram thereof. FIG. 3 is an SEM photograph showing another cross-sectional structure of the negative electrode shown in FIG. 2 and a schematic diagram thereof. It is sectional drawing showing the structure of the 4th secondary battery provided with the electrolyte solution which concerns on one embodiment of this invention. It is sectional drawing along the VIII-VIII line of the wound electrode body shown in FIG. It is a figure showing the analysis result of SnCoC containing material by XPS.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 15A ... Disc board, 16 ... Heat sensitive resistance element, 17 ... Gasket, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode current collector, 21B, 33B ... Positive electrode active material layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode current collector, 22B, 34B ... Negative electrode active material layer, 23, 35 ... Separator 24 ... Center pin, 25, 31 ... Positive electrode lead, 26, 32 ... Negative electrode lead, 36 ... Electrolyte, 37 ... Protective tape, 40 ... Exterior member, 41 ... Adhesive film, 221 ... Negative electrode active material particle, 222 ... Oxide Containing film, 224 (224A, 224B) ... gap, 225 ... gap, 226 ... metal material.

Claims (40)

The electrolyte solution characterized by including the solvent containing the isocyanate compound represented by Chemical formula 1.

(R1 is a z-valent organic group, and z is an integer of 2 or more, provided that the carbon atom in the carbonyl group (—CO—) is bonded to the carbon atom in R1.) The electrolyte solution according to claim 1, wherein the isocyanate compound represented by the chemical formula 1 is a compound represented by the chemical formula 2.

(R2 is a divalent organic group. However, the carbon atom in the carbonyl group is bonded to the carbon atom in R2.)   The electrolytic solution according to claim 2, wherein R2 in the chemical formula 2 is a linear alkylene group. R2 in the formula 2 is an ethylene group (-C ₂ H ₄ -) or a propylene group (-C ₃ H ₆ -) electrolyte according to claim 2, characterized in that the.   2. The electrolytic solution according to claim 1, wherein the content of the isocyanate compound represented by Chemical Formula 1 in the solvent is 0.01 wt% or more and 5 wt% or less. 2. The electrolysis according to claim 1, wherein the solvent contains at least one of a chain carbonate having a halogen represented by Chemical Formula 3 and a cyclic carbonate having a halogen represented by Chemical Formula 4. 3. liquid.

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

(R17 to R20 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)   The chain carbonate having halogen shown in Chemical Formula 3 is fluoromethyl methyl carbonate, difluoromethyl methyl carbonate or bis (fluoromethyl) carbonate, and the cyclic carbonate having halogen shown in Chemical Formula 4 is 4- The electrolytic solution according to claim 6, which is fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one. The electrolytic solution according to claim 1, wherein the solvent contains a cyclic carbonate having an unsaturated bond represented by Chemical Formula 5 to Chemical Formula 7.

(R21 and R22 are a hydrogen group or an alkyl group.)

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

(R27 is an alkylene group.)   The cyclic ester carbonate having an unsaturated bond shown in Chemical Formula 5 is vinylene carbonate, and the cyclic carbonate ester having an unsaturated bond shown in Chemical Formula 6 is vinylethylene carbonate. The electrolytic solution according to claim 8, wherein the cyclic carbonate having a saturated bond is methylene ethylene carbonate. At least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), and lithium hexafluoroarsenate (LiAsF ₆ ) The electrolyte solution according to claim 1, comprising an electrolyte salt containing The electrolyte solution according to claim 1, comprising an electrolyte salt containing at least one member selected from the group consisting of compounds represented by chemical formulas 8 to 10.

(X31 is a group 1 element or group 2 element in the long-period periodic table, or aluminum (Al). M31 is a transition metal element, or a group 13 element, group 14 element, or group 15 element in the long-period periodic table. R31 is a halogen group, Y31 is — (O═) C—R32—C (═O) —, — (O═) C—C (R33) ₂ — or — (O═) C—C ( ═O) —, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, and R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group. A3 is an integer of 1 to 4, b3 is 0, 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

(X41 is a group 1 element or group 2 element in the long periodic table. M41 is a transition metal element, or a group 13, element or group 15 element in the long period periodic table. Y41 is − ( O =) C- (C (R41 ) 2) b4 -C (= O) -, - (R43) 2 C- (C (R42) 2) c4 -C (= O) -, - (R43) 2 C -(C (R42) ₂ ) _c4 -C (R43) ₂ -,-(R43) ₂ C- (C (R42) ₂ ) _c4 -S (= O) ₂ -,-(O =) ₂ S- ( C (R42) ₂ ) _d4- S (= O) _2- or-(O =) C- (C (R42) ₂ ) _d4- S (= O) _2- where R41 and R43 are hydrogen groups. , An alkyl group, a halogen group, or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R42 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, wherein a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, and c4 Is an integer from 0 to 4, and f4 and m4 are integers from 1 to 3.)

(X51 is a group 1 element or group 2 element in the long-period periodic table. M51 is a transition metal element, or a group 13, element or group 15 element in the long-period periodic table. Rf is fluorinated. An alkyl group or a fluorinated aryl group, each having 1 to 10 carbon atoms Y51 is — (O═) C— (C (R51) ₂ ) _d5 —C (═O) —, — (R52); ₂ C- (C (R51) ₂ ) _d5 -C (= O)-,-(R52) ₂ C- (C (R51) ₂ ) _d5 -C (R52) ₂ -,-(R52) ₂ C- ( _{C (R51) 2) d5 -S} (= O) 2 -, - (O =) 2 S- (C (R51) 2) e5 -S (= O) 2 - or - (O =) C- (C _{(R51) 2) e5 -S (} = O) 2 -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group, or a halogen Kaa R52 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.) The compounds represented by the chemical formula 8 are compounds represented by chemical formulas (1) to (6), and the compounds represented by the chemical formula 9 are represented by chemical formulas (1) to (8). The electrolyte solution according to claim 11, wherein the electrolyte is a compound represented by the chemical formula 10:

The electrolyte solution according to claim 1, comprising an electrolyte salt containing at least one member selected from the group consisting of compounds represented by chemical formulas 14 to 16.

(M and n are integers of 1 or more.)

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

(P, q and r are integers of 1 or more.)   The electrolytic solution according to claim 1, comprising sultone.   The electrolytic solution according to claim 1, comprising an acid anhydride.   The electrolytic solution according to claim 1, wherein the electrolytic solution is used in a secondary battery. A secondary battery comprising an electrolyte solution together with a positive electrode and a negative electrode,
The said electrolyte solution contains the solvent containing the isocyanate compound represented by Chemical formula 17. The secondary battery characterized by the above-mentioned.

(R1 is a z-valent organic group, and z is an integer of 2 or more, provided that the carbon atom in the carbonyl group is bonded to the carbon atom in R1.) The secondary battery according to claim 17, wherein the isocyanate compound represented by Chemical Formula 17 is a compound represented by Chemical Formula 18:

(R2 is a divalent organic group. However, the carbon atom in the carbonyl group is bonded to the carbon atom in R2.)   The secondary battery according to claim 18, wherein R 2 in the chemical formula 18 is a linear alkylene group.   The secondary battery according to claim 18, wherein R 2 in the chemical formula 18 is an ethylene group or a propylene group.   The secondary battery according to claim 17, wherein the content of the isocyanate compound represented by Chemical Formula 17 in the solvent is 0.01 wt% or more and 5 wt% or less. 18. The solvent according to claim 17, wherein the solvent contains at least one of a chain carbonate having a halogen represented by Chemical Formula 19 and a cyclic carbonate having a halogen represented by Chemical Formula 20. Next battery.

(R11 to R16 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

(R17 to R20 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)   The chain carbonate having a halogen shown in Chemical Formula 19 is fluoromethyl methyl carbonate, difluoromethyl methyl carbonate or bis (fluoromethyl) carbonate, and the cyclic carbonate having a halogen shown in Chemical Formula 20 is 4- The secondary battery according to claim 22, wherein the secondary battery is fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one. The secondary battery according to claim 17, wherein the solvent contains a cyclic carbonate having an unsaturated bond represented by Chemical Formula 21 to Chemical Formula 23.

(R21 and R22 are a hydrogen group or an alkyl group.)

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

(R27 is an alkylene group.)   The cyclic carbonate having an unsaturated bond shown in Chemical Formula 21 is vinylene carbonate, and the cyclic carbonate having an unsaturated bond shown in Chemical Formula 22 is vinylethylene carbonate. The secondary battery according to claim 24, wherein the cyclic carbonate having a saturated bond is methylene ethylene carbonate.   18. An electrolyte salt containing at least one member selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate. Secondary battery. The secondary battery according to claim 17, comprising an electrolyte salt containing at least one member selected from the group consisting of compounds represented by chemical formulas 24 to 26:

(X31 is a group 1 element or group 2 element in the long-period periodic table, or aluminum (Al). M31 is a transition metal element, or a group 13 element, group 14 element, or group 15 element in the long-period periodic table. R31 is a halogen group, Y31 is — (O═) C—R32—C (═O) —, — (O═) C—C (R33) ₂ — or — (O═) C—C ( ═O) —, wherein R32 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, and R33 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group. A3 is an integer of 1 to 4, b3 is 0, 2 or 4, and c3, d3, m3 and n3 are integers of 1 to 3.)

(X41 is a group 1 element or group 2 element in the long periodic table. M41 is a transition metal element, or a group 13, element or group 15 element in the long period periodic table. Y41 is − ( O =) C- (C (R41 ) 2) b4 -C (= O) -, - (R43) 2 C- (C (R42) 2) c4 -C (= O) -, - (R43) 2 C -(C (R42) ₂ ) _c4 -C (R43) ₂ -,-(R43) ₂ C- (C (R42) ₂ ) _c4 -S (= O) ₂ -,-(O =) ₂ S- ( C (R42) ₂ ) _d4- S (= O) _2- or-(O =) C- (C (R42) ₂ ) _d4- S (= O) _2- where R41 and R43 are hydrogen groups. , An alkyl group, a halogen group, or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R42 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, wherein a4, e4 and n4 are 1 or 2, b4 and d4 are integers of 1 to 4, and c4 Is an integer from 0 to 4, and f4 and m4 are integers from 1 to 3.)

(X51 is a group 1 element or group 2 element in the long-period periodic table. M51 is a transition metal element, or a group 13, element or group 15 element in the long-period periodic table. Rf is fluorinated. An alkyl group or a fluorinated aryl group, each having 1 to 10 carbon atoms Y51 is — (O═) C— (C (R51) ₂ ) _d5 —C (═O) —, — (R52); ₂ C- (C (R51) ₂ ) _d5 -C (= O)-,-(R52) ₂ C- (C (R51) ₂ ) _d5 -C (R52) ₂ -,-(R52) ₂ C- ( _{C (R51) 2) d5 -S} (= O) 2 -, - (O =) 2 S- (C (R51) 2) e5 -S (= O) 2 - or - (O =) C- (C _{(R51) 2) e5 -S (} = O) 2 -. is, however, R51 is a hydrogen group, an alkyl group, a halogen group, or a halogen Kaa R52 is a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a5, f5 and n5 are 1 or 2; B5, c5 and e5 are integers of 1 to 4, d5 is an integer of 0 to 4, and g5 and m5 are integers of 1 to 3.) The compounds represented by the chemical formula 24 are compounds represented by chemical formulas (1) to (6), and the chemical compounds represented by the chemical formula 25 are represented by chemical formulas (1) to (8). 28. The secondary battery according to claim 27, wherein the compound represented by the chemical formula 26 is a compound represented by the chemical formula 29.

The secondary battery according to claim 17, comprising an electrolyte salt containing at least one selected from the group consisting of compounds represented by chemical formulas 30 to 32.

(M and n are integers of 1 or more.)

(R61 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

(P, q and r are integers of 1 or more.)   The secondary battery according to claim 17, comprising sultone.   The secondary battery according to claim 17, comprising an acid anhydride.   The negative electrode is a negative electrode active material containing a carbon material, lithium metal (Li), or a material that can occlude and release lithium and has at least one of a metal element and a semi-metal element. The secondary battery according to claim 17, further comprising:   The negative electrode includes a negative electrode active material containing at least one selected from the group consisting of a simple substance, an alloy and a compound of silicon (Si), and a simple substance, an alloy and a compound of tin (Sn). The secondary battery according to 17.   The negative electrode has a negative electrode active material layer on a negative electrode current collector, and the negative electrode active material layer is formed by at least one method selected from the group consisting of a vapor phase method, a liquid phase method, and a firing method. The secondary battery according to claim 17.   The negative electrode has a negative electrode active material layer including a plurality of negative electrode active material particles, and the negative electrode active material layer includes an oxide-containing film that covers a surface of the negative electrode active material particles. The secondary battery according to 17.   36. The secondary battery according to claim 35, wherein the oxide-containing film contains at least one oxide selected from the group consisting of silicon, germanium (Ge), and tin.   The negative electrode has a negative electrode active material layer including a plurality of negative electrode active material particles, and the negative electrode active material layer includes a metal material that does not alloy with an electrode reactant provided in a gap inside the negative electrode active material layer. The secondary battery according to claim 17.   38. The secondary battery according to claim 37, wherein the metal material is provided in a gap between the negative electrode active material particles.   38. The secondary battery according to claim 37, wherein the negative electrode active material particles have a multilayer structure in the particles, and the metal material is provided in a gap in the negative electrode active material particles.   The secondary material according to claim 37, wherein the metal material contains at least one of iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), and copper (Cu). battery.

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