JP4819409B2 - Non-aqueous electrolyte secondary battery charge / discharge method - Google Patents

Description

  The present invention relates to an additive used for an electrolytic solution of an electrochemical device, an electrolytic solution for a secondary battery, and a secondary battery using the same.

  Non-aqueous electrolyte lithium ion or lithium secondary battery using carbon material or lithium metal for the negative electrode and lithium-containing composite oxide for the positive electrode can realize high energy density, so it can be used as a power source for mobile phones and laptop computers. Attention has been paid. In this secondary battery, it is generally known that a film called a surface film, a protective film, SEI or a film is formed on the surface of the electrode. Since this surface film has a great influence on charge / discharge efficiency, cycle life, and safety, it is known that control of the surface film is indispensable for improving the performance of the electrode. That is, when a carbon material is used as the negative electrode material, it is necessary to reduce the irreversible capacity, and in the lithium metal negative electrode, it is necessary to solve the problem of safety due to the decrease in charge / discharge efficiency and the generation of dendrite.

  Various techniques have been proposed as a technique for solving these problems. For example, when lithium metal is used as the negative electrode material, it has been proposed to suppress the formation of dendrite by providing a coating layer made of lithium fluoride or the like on the surface using a chemical reaction.

Patent Document 1 discloses a technique in which a lithium negative electrode is exposed to an electrolytic solution containing hydrofluoric acid, and the negative electrode is reacted with hydrofluoric acid to cover the surface with a lithium fluoride film. Hydrofluoric acid is produced by the reaction of LiPF ₆ and a small amount of water. On the other hand, a surface film of lithium hydroxide or lithium oxide is formed on the surface of the lithium negative electrode by natural oxidation in air. When these react, a surface film of lithium fluoride is formed on the negative electrode surface. However, this lithium fluoride film is formed by utilizing the reaction between the electrode interface and the liquid, and side reaction components are likely to be mixed into the surface film, and it may be difficult to obtain a uniform film. . Also, there may be cases where the surface film of lithium hydroxide or lithium oxide is not uniformly formed or there is a part where lithium is exposed. In these cases, a uniform thin film cannot be formed. In addition, there has been a safety problem due to the reaction of lithium with water or hydrogen fluoride. Moreover, when reaction is inadequate, unnecessary compound components other than a fluoride remain, and bad influences, such as causing the fall of ion conductivity, are considered. Furthermore, in the method of forming a fluoride layer using such a chemical reaction at the interface, the selection range of available fluorides and electrolytes is limited, and it is difficult to form a stable surface film with a high yield. There was a case.

  In Patent Document 2, a mixed gas of argon and hydrogen fluoride and an aluminum-lithium alloy are reacted to obtain a lithium fluoride surface film on the negative electrode surface. However, when a surface film is preliminarily present on the surface of the lithium metal, particularly when a plurality of types of compounds are present, the reaction tends to be non-uniform and it may be difficult to form a lithium fluoride film uniformly. It was. In this case, it is difficult to obtain a lithium secondary battery having sufficient cycle characteristics.

  Patent Document 3 discloses a technique for forming a surface film structure mainly composed of a substance having a rock salt type crystal structure on the surface of a lithium sheet having a uniform crystal structure, that is, a (100) crystal plane preferentially oriented. It is disclosed. By carrying out like this, it is said that uniform precipitation dissolution reaction, ie, charge / discharge of a battery, can be performed, dendrite precipitation of lithium metal can be suppressed, and the cycle life of the battery can be improved. It is stated that it is preferable to use lithium halide as the material used for the surface film, and it is preferable to use a solid solution of LiF and at least one selected from the group consisting of LiCl, LiBr and LiI. Yes. Specifically, in order to form a solid solution film with LiF and at least one selected from the group consisting of LiCl, LiBr, and LiI, the (100) crystal plane prepared by pressing (rolling) is preferentially oriented. The lithium sheet is selected from the group consisting of (1) to (3) among (1) chlorine molecules or chlorine ions, (2) bromine molecules or bromine ions, and (3) iodine molecules or iodine ions. A negative electrode for a non-aqueous electrolyte battery is produced by immersing in an electrolytic solution containing at least one kind and fluorine molecules or fluorine ions. In the case of this technology, a rolled lithium metal sheet is used, and since the lithium sheet is easily exposed to the atmosphere, a film derived from moisture and the like is easily formed on the surface, and the presence of active sites becomes uneven, which is the purpose. In some cases, it is difficult to produce a stable surface film. In this case, the effect of suppressing dentlite is not always sufficiently obtained.

  In addition, when a carbon material such as graphite or hard carbon capable of occluding and releasing lithium ions is used as the negative electrode, a technique for improving capacity and charge / discharge efficiency has been reported.

  In patent document 4, the negative electrode which coat | covered the carbon material with aluminum is proposed. Thereby, reductive decomposition on the carbon surface of solvent molecules solvated with lithium ions is suppressed, and deterioration of cycle life is suppressed. However, since aluminum reacts with a small amount of water, the capacity may decrease rapidly when the cycle is repeated.

  Patent Document 5 proposes a negative electrode in which a surface of a carbon material is covered with a thin film of a lithium ion conductive solid electrolyte. Thereby, it is said that the decomposition | disassembly of the solvent which arises when using a carbon material can be suppressed, and especially the lithium ion secondary battery which can use a propylene carbonate can be provided. However, cracks generated in the solid electrolyte due to changes in stress during insertion and desorption of lithium ions may lead to deterioration of characteristics. Further, due to non-uniformity such as crystal defects of the solid electrolyte, a uniform reaction cannot be obtained on the negative electrode surface, leading to deterioration of cycle life.

  Further, in Patent Document 6, the negative electrode is made of a material containing graphite, the main component is a cyclic carbonate and a chain carbonate as an electrolytic solution, and 0.1% by mass or more and 4% by mass or less of a cyclic monolith in the electrolytic solution. A secondary battery containing sulfonic acid ester 1,3-propane sultone and / or 1,4-butane sultone is disclosed. Here, 1,3-propane sultone or 1,4-butane sultone contributes to the formation of a passive film on the surface of the carbon material, and the active and highly crystallized carbon material such as natural graphite or artificial graphite is a passive film. It is considered that the coating has an effect of suppressing the decomposition of the electrolyte without impairing the normal reaction of the battery. In addition to the cyclic monosulfonic acid ester, Patent Documents 7 and 8 report that the same effect can be obtained by using a chain disulfonic acid ester. However, the cyclic monosulfonate of Patent Document 6 or the chain disulfonate of Patent Document 7 and Patent Document 8 mainly forms a film on the negative electrode. For example, a film may be formed on the positive electrode. It was sometimes difficult. Patent Documents 9 and 10 disclose a method for producing a cyclic sulfonic acid ester having two sulfonyl groups, and Non-Patent Documents 1 to 4 disclose a method for producing a chain disulfonic acid ester.

In Patent Document 11, by adding an aromatic compound to the electrolytic solution solvent, the deterioration of the capacity when the secondary battery is repeatedly charged and discharged over a long period of time is suppressed by preventing oxidation of the electrolytic solution solvent. This is a technique for preventing the decomposition of the solvent by preferentially oxidatively decomposing the aromatic compound. However, when this additive is used, the positive electrode surface is not coated, so that the effect of improving the cycle characteristics may not be sufficient.
Patent Document 12 describes a technique for improving cycle characteristics when a high-voltage positive electrode is used by adding a nitrogen-containing unsaturated cyclic compound to an electrolytic solution. However, although the nitrogen-containing unsaturated cyclic compound improves the charge / discharge efficiency of the negative electrode, it does not improve the charge / discharge efficiency of the positive electrode.
JP-A-7-302617 JP-A-8-250108 Japanese Patent Laid-Open No. 11-288706 Japanese Patent Laid-Open No. 5-234583 JP-A-5-275077 JP 2000-3724 A JP 2000-133304 A US Pat. No. 6,436,582 Japanese Patent Publication No. 5-44946 U.S. Pat. No. 4,950,768 J. et al. Am. Pham. Assoc. L26, 485-493, 1937 G. Schroeter, Lieb, Ann, Der Chemie, 418, 161-257, 1919 Biol. Aktiv. Soedin. Pp 64-69 (1968). Armyanskii Kimicheskii Zhurnal, 21, pp 393-396 (1968). JP 2003-7334 A JP 2003-115324 A

  The above prior art has the following common problems. The surface film formed on the electrode surface is deeply related to charge / discharge efficiency, cycle life, and safety depending on its properties. However, the above-mentioned conventional technology mainly forms a stable film on the negative electrode, and the negative electrode and the positive electrode. A technique for stably forming a film on both the electrodes has not been disclosed.

  In addition, in the conventional technique for forming a film on the positive electrode, there has not yet been a technique for controlling the film over a long period of time. For this reason, although a certain degree of suppression effect of dentite can be obtained at the initial use, the surface film may deteriorate and the function as a protective film may be deteriorated if it is used repeatedly. This is because the layer of the positive electrode active material containing lithium changes its volume by occluding and releasing lithium, while the film formed on the surface hardly changes in volume. This is thought to be due to the occurrence of internal stress. Due to the occurrence of such internal stress, it is considered that a part of the surface film is broken and the dendrite suppressing function is lowered. As a result, the electrolytic solution was decomposed, and it was difficult to maintain a high discharge capacity and excellent cycle characteristics.

  In addition, even when the above prior art is used, when a carbon material such as graphite is used for the negative electrode, charges due to decomposition of solvent molecules or anions may appear as irreversible capacity components, leading to a decrease in initial charge / discharge efficiency. there were. In some cases, the composition, crystal state, stability, and the like of the resulting film have a great adverse effect on the subsequent efficiency and cycle life.

  Therefore, as a method of forming a stable film on the surface of the electrode (positive electrode / negative electrode) and preventing decomposition of the non-aqueous electrolyte component, a method of adding a chain disulfonic acid ester to the non-aqueous electrolyte solution can be considered. This chain disulfonic acid ester is considered to have a function of forming a stable film on the electrode surface by a film forming reaction and effectively suppressing the decomposition of the non-aqueous electrolyte. However, the film formation reaction of the chain disulfonic acid ester is greatly influenced by the charging conditions of the secondary battery, and the characteristics of the secondary battery in which the chain disulfonic acid ester is added to the electrolyte solution. Charging / discharging conditions that can be maximized have not yet been fully studied.

  In particular, in a laminate type secondary battery in which the chain disulfonic acid ester is added to the electrolytic solution, the influence of the charge / discharge conditions is conspicuous in the battery characteristics, so that it is necessary to sufficiently examine the charge / discharge conditions.

  This invention is made | formed in view of the said subject, By adding chain | strand-shaped disulfonic acid ester in the non-aqueous electrolyte for secondary batteries, and setting charging / discharging conditions, such as charge temperature, to predetermined conditions. An object of the present invention is to provide charging / discharging conditions that can optimize secondary battery characteristics such as cycle characteristics and storage characteristics.

In order to solve the above problems, the present invention has the following configuration.
1. A charge / discharge method of a non-aqueous electrolyte secondary battery having an electrolyte solution containing at least an aprotic solvent in which an electrolyte is dissolved and a compound represented by the following general formula (1):
Charging / discharging of a non-aqueous electrolyte secondary battery, wherein charging is performed at a temperature in the range of 30 to 60 ° C.

（但し、上記一般式（１）において、Ｒ₁およびＲ₄は、それぞれ独立して、水素原子、置換もしくは無置換の炭素数１〜５のアルキル基、置換もしくは無置換の炭素数１〜５のアルコキシ基、置換もしくは無置換の炭素数１〜５のフルオロアルキル基、炭素数１〜５のポリフルオロアルキル基、−ＳＯ₂Ｘ₁（Ｘ₁は置換もしくは無置換の炭素数１〜５のアルキル基）、−ＳＹ₁（Ｙ₁は置換もしくは無置換の炭素数１〜５のアルキル基）、−ＣＯＺ（Ｚは水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、及びハロゲン原子、から選ばれる原子または基を示す。Ｒ₂およびＲ₃は、それぞれ独立して、置換もしくは無置換の炭素数１〜５のアルキル基、置換もしくは無置換の炭素数１〜５のアルコキシ基、置換もしくは無置換のフェノキシ基、置換もしくは無置換の炭素数１〜５のフルオロアルキル基、炭素数１〜５のポリフルオロアルキル基、置換もしくは無置換の炭素数１〜５のフルオロアルコキシ基、炭素数１〜５のポリフルオロアルコキシ基、水酸基、ハロゲン原子、−ＮＸ₂Ｘ₃（Ｘ₂及びＸ₃は、それぞれ独立して、水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、及び−ＮＹ₂ＣＯＮＹ₃Ｙ₄（Ｙ₂〜Ｙ₄は、それぞれ独立して、水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、から選ばれる原子または基を示す。）。

(However, in the said General formula (1), R < ₁ > and R < ₄ > are respectively independently a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C1-C5. An alkoxy group, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a polyfluoroalkyl group having 1 to 5 carbon atoms, —SO ₂ X ₁ (wherein X ₁ is a substituted or unsubstituted carbon atom having 1 to 5 carbon atoms). alkyl group), - SY ₁ (Y ₁ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), - COZ (Z is a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), And R ₂ and R ₃ each independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted carbon group having 1 to 5 carbon atoms. Alkoxy group, substituted or absent Substituted phenoxy group, substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, polyfluoroalkyl group having 1 to 5 carbon atoms, substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, 1 to carbon atoms 5 polyfluoroalkoxy group, hydroxyl group, halogen atom, —NX ₂ X ₃ (X ₂ and X ₃ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), and _{-NY 2 CONY 3 Y 4 (Y} 2 ~Y 4 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), indicating the atom or a group selected from.).

2. 2. The charge / discharge method for a non-aqueous electrolyte secondary battery according to 1 above, wherein the charging is performed at a temperature in the range of 40 to 55 ° C.
3. 3. The charging / discharging method for a non-aqueous electrolyte secondary battery according to 1 or 2 above, wherein the charging is charging of a non-aqueous electrolyte secondary battery in an initial state.

4). 4. The charge / discharge method for a non-aqueous electrolyte secondary battery according to any one of 1 to 3 above, wherein a charge end voltage at the time of charging is 3.4 V or more.
5). The ratio C _d / C _c between the discharge capacity C _d at the time of discharge and the charge capacity C _c at the time of charge is 0.5 to 0.95, any one of the above 1 to 4, Charge / discharge method of non-aqueous electrolyte secondary battery.

  6). The non-aqueous solution according to any one of 1 to 5 above, wherein the compound represented by the general formula (1) is contained in the electrolytic solution at a content of 0.1 to 5.0% by mass. A method for charging and discharging an electrolyte secondary battery.

  7). 7. The charge / discharge of the nonaqueous electrolyte secondary battery according to any one of 1 to 6 above, wherein the electrolyte further contains a cyclic monosulfonic acid ester represented by the following general formula (2): Method.

（但し、上記一般式（２）において、ｎは０以上２以下の整数である。また、Ｒ₅〜Ｒ₁₀は、それぞれ独立して水素原子、置換もしくは無置換の炭素数１〜１２のアルキル基、置換もしくは無置換の炭素数１〜６のフルオロアルキル基、及び炭素数１〜６のポリフルオロアルキル基、から選ばれる原子または基を示す。）。

(However, in the general formula (2), n is 0 to 2 integer. Also, R ₅ to R ₁₀ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl having 1 to 12 carbon atoms An atom or group selected from a group, a substituted or unsubstituted fluoroalkyl group having 1 to 6 carbon atoms, and a polyfluoroalkyl group having 1 to 6 carbon atoms.

  8). 8. The nonaqueous electrolytic solution according to any one of 1 to 7 above, wherein the electrolytic solution further contains a cyclic sulfonic acid ester having two sulfonyl groups represented by the following general formula (3). Secondary battery charge / discharge method.

（但し、上記一般式（３）において、Ｑは酸素原子、メチレン基または単結合、Ａは、置換もしくは無置換の炭素数１〜５のアルキレン基、カルボニル基、スルフィニル基、炭素数１〜５のポリフルオロアルキレン基、置換もしくは無置換の炭素数１〜５のフルオロアルキレン基、置換もしくは無置換の炭素数１〜５のアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、炭素数１〜５のポリフルオロアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、及び置換もしくは無置換の炭素数１〜５のフルオロアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、から選ばれる基を示す。Ｂは、置換もしくは無置換の炭素数１〜５のアルキレン基、炭素数１〜５のポリフルオロアルキレン基、及び置換もしくは無置換の炭素数１〜５のフルオロアルキレン基から選ばれる基を示す。）。

(However, in the said General formula (3), Q is an oxygen atom, a methylene group, or a single bond, A is a substituted or unsubstituted C1-C5 alkylene group, a carbonyl group, a sulfinyl group, C1-C5. At least one C—C bond in the polyfluoroalkylene group, a substituted or unsubstituted fluoroalkylene group having 1 to 5 carbon atoms, or a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms is a C—O—C bond A group in which at least one C—C bond in the polyfluoroalkylene group having 1 to 5 carbon atoms is a C—O—C bond, and a substituted or unsubstituted fluoroalkylene having 1 to 5 carbon atoms A group selected from a group in which at least one CC bond in the group is a C—O—C bond, B is a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, carbon 1-5 polyfluoroalkylene group, and a substituted or unsubstituted group selected from fluoroalkylene group having 1 to 5 carbon atoms.).

  In the present invention, “charging of the non-aqueous electrolyte secondary battery in the initial state” means that charging is performed first after the non-aqueous electrolyte secondary battery is formed. Whether or not this charge is for the secondary battery in the initial state depends on the surface state of the electrode (whether film formation, presence / absence of components generated during charge / discharge) and electrolyte component (presence / absence of components generated during charge / discharge) ) Etc. can be confirmed.

  In this specification, “polyfluoroalkylene group”, “polyfluoroalkyl group”, and “polyfluoroalkoxy group” are all hydrogen atoms bonded to carbon atoms of the corresponding alkylene group, alkyl group, and alkoxy group, respectively, by fluorine atoms. Represents a substituted group, and “fluoroalkylene group”, “fluoroalkyl group”, and “fluoroalkoxy group” are fluorine atoms in which part of hydrogen atoms bonded to carbon atoms of the corresponding alkylene group, alkyl group, and alkoxy group, respectively. Represents the one substituted by.

In the “substituted fluoroalkylene group”, “substituted fluoroalkyl group” and “substituted fluoroalkoxy group”, “substituted” means that at least one hydrogen atom bonded to a carbon atom is substituted with an atom or functional group other than fluorine. Represents that Examples of the atom or functional group other than fluorine include, for example, a halogen atom such as a chlorine atom, a bromine atom, and an iodine atom, a hydroxyl group, or an alkoxy group having 1 to 5 carbon atoms, or a group in which this is substituted with a halogen atom or a hydroxyl group. Or a group in which —SO ₂ — is introduced into these groups (for example, —OSO ₂ CH ₂ SO ₂ Cl). When this functional group contains a carbon atom, this carbon atom is not included in the number of “C1-5” in the description of “substituted or unsubstituted alkyl group having 1 to 5 carbon atoms” and the like. And

  According to the present invention, by performing charging and discharging at a predetermined temperature using a secondary battery electrolyte containing a chain disulfonic acid ester in an aprotic solvent, the storage characteristics are excellent, and the cycle characteristics are good. An excellent lithium secondary battery with little voltage drop and little volume increase can be obtained.

  The present invention provides a charge / discharge method capable of obtaining excellent cycle characteristics and storage characteristics in a non-aqueous electrolyte secondary battery having an electrolyte solution to which a chain disulfonic acid ester is added.

(Charge / discharge conditions)
(1) Temperature at the time of charging / discharging The temperature at the time of charge of the nonaqueous electrolyte secondary battery of this invention needs to be 30-60 degreeC. If it is less than 30 ° C., it is insufficient to promote the film formation reaction of the additive (chain disulfonic acid ester; compound of general formula (1)) added to the electrolyte, and an effective film is formed on the electrode. May not be possible. On the other hand, when the temperature exceeds 60 ° C., the decomposition reaction of the film of the chain disulfonic acid ester formed on the electrode is promoted, and the reaction rate of the decomposition reaction of the solvent and the electrolyte may increase.

  In the charge / discharge method of the present invention, in a non-aqueous electrolyte secondary battery containing a chain disulfonic acid ester in the electrolyte, the temperature during at least one charge is set to 30 to 60 ° C. The effects of the present invention can be obtained.

  When charging and discharging a plurality of times, the temperature at the time of at least one charge may be 30 to 60 ° C. Preferably, the temperature during charging of the nonaqueous electrolyte secondary battery in the initial state is 30 to 60 ° C. This is due to the following reason. When the second and subsequent charging is performed, a chain-like disulfonic acid ester film is already formed on the electrode surface during the previous charging. For this reason, the amount of the film newly formed on the electrode by this charging is small, and the contribution of the film formation and the film stability effect by using the charge / discharge method of the present invention is also reduced. On the other hand, the chain | strand-shaped disulfonate film is hardly formed in the electrode surface of the secondary battery of an initial state. For this reason, charge / discharge conditions significantly affect the film formation reaction of the chain disulfonic acid ester on the electrode surface and the stability of the film, and an excellent effect can be obtained by using the charge / discharge method of the present invention. .

  In addition, when performing charging / discharging several times, it is more preferable to perform all charge at the temperature of 30-60 degreeC. By setting the temperature at each charge in such a range, the chain formation reaction of chain disulfonic acid ester is effectively performed for each charge, and a stable film is accumulated on the electrode. I can go. In addition, in the charging / discharging method of the nonaqueous electrolyte secondary battery of the present invention, the number of cycles for charging / discharging is not particularly limited, but can be set to 5 times or more, for example, after 700 cycles. Also, the effects of the present invention can be sufficiently obtained.

  In this invention, it is preferable to set the temperature at the time of charge to the range of 40-55 degreeC, and it is more preferable to set to 45-50 degreeC. By setting the temperature at the time of charging within these ranges, a film formation reaction of a chain disulfonic acid ester can be effectively performed, and a secondary battery having more excellent cycle characteristics and storage characteristics can be obtained.

  Further, the temperature at the time of discharging is not particularly limited, but it is preferably 30 to 60 ° C., more preferably 40 to 55 ° C., and 45 to 55 ° C. as in the case of charging. Is more preferable. By setting the temperature at the time of discharge within these ranges, it is possible to effectively suppress the decomposition of the chain disulfonate film formed on the electrode surface during charging.

(2) Voltage at the time of charging / discharging In the charging / discharging method of this invention, it is preferable that the charge end voltage at the time of charging is 3.4V or more. Note that in the case of such a charge end voltage, as the positive electrode active material, LiMO ₂ (M is at least one of Mn, Fe, Co, Ni, and a part thereof is substituted with other cations such as Mg, Al, Ti, etc. Or manganese spinel compounds such as LiMn ₂ O ₄ can be used. In addition, as the negative electrode active material, a material that can occlude and release lithium, such as lithium metal and carbon material, can be used. As the carbon material, graphite that occludes lithium, amorphous carbon, diamond-like carbon, fullerene, carbon nanotube, carbon nanohorn, or a composite thereof can be used.

  By setting the end-of-charge voltage during charging to 3.4 V or higher, the stability of the film formed on the electrode can be further improved, and a secondary battery excellent in cycle characteristics and storage characteristics can be obtained. This is considered to be due to the following reasons. By setting the charge end voltage as described above, a sufficient amount of lithium ions can be electrochemically transferred from the positive electrode to the negative electrode, and the amount of lithium ions remaining on the positive electrode during charging can be reduced. As a result, it is thought that the formation inhibition of the chain | strand-shaped disulfonic-acid ester film | membrane on a positive electrode by the remaining lithium ion, the decomposition | disassembly of a film | membrane, etc. can be prevented.

Further, depending on the battery configuration, it is preferable to set the charge end voltage during charging to 4.3 V or higher. In the case of such end-of-charge voltage, as the positive electrode active material, LiCoO ₂ , Li [Co _1/3 Mn _1/3 Ni _1/3 ] O ₂ , Li _a (M _x Mn _{2 -xy} A _y ) O ₄ (Wherein 0.4 <x, 0 <y, x + y <2, 0 <a <1.2. M is at least one selected from the group consisting of Ni and Co, Fe, Cr and Cu. A includes a metal element. A includes at least one metal element of Si and Ti. However, when A includes only Ti, 0.1 <y.) Etc. can be used. As the negative electrode active material, the same materials as described above can be used.

(3) Charging capacity and discharging capacity In the charging / discharging method of the present invention, the ratio C _d / C _c between the discharging capacity C _d during discharging and the charging capacity C _c during charging is 0.5 to 0.95. Is more preferable, 0.6 to 0.9 is more preferable, and 0.6 to 0.8 is still more preferable. When the ratio C _d / C _c is within these ranges, excessive volume expansion of the electrode due to charge / discharge does not occur, and the chain-like disulfonic acid ester film formed on the electrode surface can be stably maintained.

  Moreover, when charging / discharging with a constant current constant voltage, it is preferable to set a charge rate to 0.01-1C, It is more preferable to set to 0.1-1C, It sets to 0.5-1C. More preferably.

(4) Aging temperature after charging / discharging The aging temperature after charging / discharging is preferably 20 to 70 ° C, and more preferably 30 to 50 ° C. When the aging temperature is within these ranges, problems such as battery expansion and self-discharge do not occur. In addition, problems such as storage characteristics, reduced capacity and increased resistance due to long-term use are unlikely to occur.

(Compound of general formula (1))
In the charge / discharge method of the present invention, a non-aqueous electrolyte secondary battery having an electrolytic solution to which a chain disulfonic acid ester represented by the following general formula (1) is added is used.

（但し、上記一般式（１）において、Ｒ₁およびＲ₄は、それぞれ独立して、水素原子、置換もしくは無置換の炭素数１〜５のアルキル基、置換もしくは無置換の炭素数１〜５のアルコキシ基、置換もしくは無置換の炭素数１〜５のフルオロアルキル基、炭素数１〜５のポリフルオロアルキル基、−ＳＯ₂Ｘ₁（Ｘ₁は置換もしくは無置換の炭素数１〜５のアルキル基）、−ＳＹ₁（Ｙ₁は置換もしくは無置換の炭素数１〜５のアルキル基）、−ＣＯＺ（Ｚは水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、及びハロゲン原子、から選ばれる原子または基を示す。Ｒ₂およびＲ₃は、それぞれ独立して、置換もしくは無置換の炭素数１〜５のアルキル基、置換もしくは無置換の炭素数１〜５のアルコキシ基、置換もしくは無置換のフェノキシ基、置換もしくは無置換の炭素数１〜５のフルオロアルキル基、炭素数１〜５のポリフルオロアルキル基、置換もしくは無置換の炭素数１〜５のフルオロアルコキシ基、炭素数１〜５のポリフルオロアルコキシ基、水酸基、ハロゲン原子、−ＮＸ₂Ｘ₃（Ｘ₂及びＸ₃は、それぞれ独立して、水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、及び−ＮＹ₂ＣＯＮＹ₃Ｙ₄（Ｙ₂〜Ｙ₄は、それぞれ独立して、水素原子、または置換もしくは無置換の炭素数１〜５のアルキル基）、から選ばれる原子または基を示す。）。

(However, in the said General formula (1), R < ₁ > and R < ₄ > are respectively independently a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C1-C5. An alkoxy group, a substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, a polyfluoroalkyl group having 1 to 5 carbon atoms, —SO ₂ X ₁ (wherein X ₁ is a substituted or unsubstituted carbon atom having 1 to 5 carbon atoms). alkyl group), - SY ₁ (Y ₁ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), - COZ (Z is a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), And R ₂ and R ₃ each independently represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted carbon group having 1 to 5 carbon atoms. Alkoxy group, substituted or absent Substituted phenoxy group, substituted or unsubstituted fluoroalkyl group having 1 to 5 carbon atoms, polyfluoroalkyl group having 1 to 5 carbon atoms, substituted or unsubstituted fluoroalkoxy group having 1 to 5 carbon atoms, 1 to carbon atoms 5 polyfluoroalkoxy group, hydroxyl group, halogen atom, —NX ₂ X ₃ (X ₂ and X ₃ are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), and _{-NY 2 CONY 3 Y 4 (Y} 2 ~Y 4 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms), indicating the atom or a group selected from.).

  The compound represented by the general formula (1) is an acyclic compound and does not involve a cyclization reaction during synthesis, and can be synthesized using, for example, Non-Patent Documents 1 to 4. Moreover, it can also be obtained as a by-product of the synthesis of a cyclic sulfonic acid ester having two sulfonyl groups shown in Patent Document 9. Thus, the compound represented by the general formula (1) has an advantage that an inexpensive electrolytic solution can be provided because the synthesis process is easy.

Preferred molecular structures of R ₁ and R _{4 in} the general formula (1) include ease of forming a reactive film on the electrode, stability of the compound, ease of handling, solubility in a solvent, From the viewpoint of ease of synthesis, cost, etc., each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom, and —SO ₂ X ₁ (X ₁ is a substituted or unsubstituted carbon atom having 1 to Atoms or groups selected from (5 alkyl groups), each independently preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms, more preferably a hydrogen atom or a methyl group. Particularly preferred embodiments of R ₁ and R ₄ is where R ₁ and R ₄ is a hydrogen atom. This is because when R ₁ and R ₄ are hydrogen atoms, the methylene moiety sandwiched between the two sulfonyl groups is activated and a reaction film on the electrode is easily formed.

In addition, in R ₂ and R ₃ , from the viewpoints of stability of the compound, ease of synthesis of the compound, solubility in a solvent, price, and the like, each independently substituted or unsubstituted alkyl having 1 to 5 carbon atoms A group, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted phenoxy group, a hydroxyl group, a halogen atom, and —NX ₂ X ₃ (X ₂ and X ₃ are each independently a hydrogen atom; Or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms) is preferable, and each independently is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or substituted or unsubstituted. The alkoxy group having 1 to 5 carbon atoms is more preferable, and one or both of R ₂ and R ₃ are more preferably substituted or unsubstituted alkoxy groups having 1 to 5 carbon atoms. For the same reason, the substituted or unsubstituted alkyl group having 1 to 5 carbon atoms is preferably a methyl group or ethyl group, and the substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms is a methoxy group or An ethoxy group is preferable.

  The compound of the general formula (1) has two sulfonyl groups, has a small LUMO, and has a smaller LUMO value than solvent molecules and monosulfonic acid esters in the electrolytic solution, and thus is easily reduced. For example, Compound No. 1 shown in Table 1 below. The LUMO of 1 is as small as -0.86 eV according to semiempirical molecular orbital calculation. For this reason, compound No. 1 is preceded by a solvent (LUMO: about 1.2 eV) comprising a cyclic carbonate or a chain carbonate. It is considered that 1 reduction film is formed on the negative electrode and plays a role of suppressing decomposition of the solvent molecules. In order to suppress the decomposition of the solvent molecules, it is difficult to form a highly resistant solvent molecule decomposition film on the negative electrode, so that an increase in resistance and an improvement in cycle characteristics can be expected. Moreover, it is considered that two electron-withdrawing sulfonyl groups are bonded to the carbon atom, and a film is easily formed on the electrode by the activation of the carbon atom. Furthermore, it is considered that the carbanion produced by deprotonation of active methylene coordinates Li or reacts on the positive electrode to form a film. Although the specific example of General formula (1) is shown below, this invention is not specifically limited to these.

一般式（１）で表される化合物は、特に限定されないが電解液中に０．１質量％以上５．０質量％以下含まれることが好ましい。０．１質量％未満では電極表面での電気化学反応による皮膜形成に十分効果が発揮されない場合がある。また、５．０質量％を越えると溶解しにくくなるだけでなく電解液の粘性を大きくしてしまう場合がある。本発明においてより好ましくは、１．０質量％〜３．０質量％の範囲で添加することにより、充放電時に皮膜による溶媒分解の抑制効果を十分に得ることができる。

Although the compound represented by General formula (1) is not specifically limited, It is preferable that 0.1 to 5.0 mass% is contained in electrolyte solution. If it is less than 0.1% by mass, a sufficient effect may not be exhibited in forming a film by an electrochemical reaction on the electrode surface. Moreover, when it exceeds 5.0 mass%, it not only becomes difficult to melt | dissolve, but the viscosity of electrolyte solution may be enlarged. In the present invention, more preferably, by adding in the range of 1.0% by mass to 3.0% by mass, the effect of suppressing the decomposition of the solvent by the film during charge / discharge can be sufficiently obtained.

You may use the compound shown in General formula (1) individually or in combination of 2 or more types. When two or more types are used in combination, there is no particular limitation, but at least one of them contains a compound having an active methylene group (that is, a compound in which R ₁ and R ₄ are hydrogen) from the viewpoint of easy film formation with an electrode Is effective. As a specific combination, the above-mentioned compound no. 1 (compound having an active methylene group) and compound no. 5 compounds.

  When two or more types of the compound of the general formula (1) are added to the electrolytic solution, the proportion of the electrolytic solution in the electrolytic solution is not particularly limited, but for the same reason as described above, the two types are combined to be 0.1% by mass or more and 5.0% by mass. The following is preferred. Further, when two or more kinds of the compound of the general formula (1) are added, the ratio of each compound to the total mass of the compound of the general formula (1) is not particularly limited, but the ratio of the smallest compound is 5 It is preferable that the ratio of the compound with the most mass% is 95 mass%.

  Further, the electrolyte solution containing the compound of the general formula (1) contains at least one of a cyclic monosulfonic acid ester, a cyclic sulfonic acid ester having two sulfonyl groups, an alkanesulfonic acid anhydride, and a sulfolene compound. It is also effective to use an electrolyte solution.

(Secondary battery)
FIG. 1 shows a schematic structure of an example of a battery used in the present invention. A positive electrode current collector 11, a layer 12 containing a positive electrode active material capable of inserting and extracting lithium ions, a layer 13 containing a negative electrode active material capable of inserting and extracting lithium ions, a negative electrode current collector 14, It is comprised from the electrolyte solution 15 and the separator 16 containing this. Here, the chain disulfonic acid compound (chain disulfonic acid ester) represented by the general formula (1) is included in the electrolytic solution 15.

(Current collector)
Aluminum, stainless steel, nickel, titanium, or an alloy thereof can be used as the positive electrode current collector 11, and copper, stainless steel, nickel, titanium, or an alloy thereof can be used as the negative electrode current collector 14. .

(Separator)
As the separator 16, a polyolefin such as polypropylene or polyethylene, or a porous film such as a fluororesin is preferably used.

(Positive electrode)
The selected positive electrode active material is dispersed and kneaded in a solvent such as N-methyl-2-pyrrolidone (NMP) together with a conductive material such as carbon black and a binder such as polyvinylidene fluoride (PVDF). The layer 12 which becomes a positive electrode can be obtained by a method such as coating on a substrate such as an aluminum foil.

(Negative electrode)
When lithium metal is used as the negative electrode active material, an appropriate method such as a melt cooling method, a liquid quenching method, an atomizing method, a vacuum deposition method, a sputtering method, a plasma CVD method, a photo CVD method, a thermal CVD method, a sol-gel method, etc. Thus, the layer 13 to be the negative electrode can be obtained. In the case of carbon materials, carbon and a binder such as polyvinylidene fluoride (PVDF) are mixed, dispersed and kneaded in a solvent such as NMP, and this is applied onto a substrate such as copper foil. The layer 13 which becomes a negative electrode can be obtained by the method such as the vapor deposition method, the CVD method or the sputtering method.

(Electrolyte)
The electrolytic solution 15 includes at least an electrolyte, an aprotic solvent, and an additive.

(Electrolytes)
As the electrolyte, in the case of a lithium secondary battery, a lithium salt is used and dissolved in an aprotic solvent. The lithium salt, lithium imide _{salt, LiPF 6, LiAsF 6, LiAlCl} 4, LiClO 4, LiBF 4, LiSbF 6 , and the like. Of these, LiPF ₆ and LiBF ₄ are particularly preferable. LiN The lithium imide salt _{(C k F 2k + 1 SO} 2) (C m F 2m + 1 SO 2) (k, m are each independently 1 or 2). These can be used alone or in combination of two or more. By including these lithium salts, a high energy density can be achieved.

(Aprotic solvent)
The aprotic solvent is selected from cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, γ-lactones, cyclic ethers, chain ethers and organic solvents of these fluorinated derivatives. In addition, at least one organic solvent is used. More specifically,
Cyclic carbonates: propylene carbonate (hereinafter abbreviated as PC), ethylene carbonate (hereinafter abbreviated as EC), butylene carbonate (BC), and their derivative chain carbonates: dimethyl carbonate (DMC), diethyl carbonate ( Hereinafter, abbreviated as DEC.), Ethyl methyl carbonate (EMC), dipropyl carbonate (DPC), and their derivatives aliphatic carboxylic acid esters: methyl formate, methyl acetate, ethyl propionate, and their derivatives γ-lactone Class: γ-butyrolactone and derivatives thereof Cyclic ethers: Tetrahydrofuran, 2-methyltetrahydrofuran, and derivatives thereof Chain ethers: 1,2-diethoxyethane (DEE), ethoxymethoxyethane (EME), Diethyl ether, and derivatives thereof, etc .: dimethyl sulfoxide, 1,3-dioxolane, formamide, acetamide, dimethylformamide, acetonitrile, propionitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, methyl Sulfolane, 1,3-dimethyl-2-imidazolidinone, 3-methyl-2-oxazolidinone, anisole, N-methylpyrrolidone, fluorinated carboxylic acid ester These may be used alone or in combination of two or more. .

  Examples of the cyclic monosulfonic acid ester include compounds represented by the following general formula (2).

（但し、上記一般式（２）において、ｎは０以上２以下の整数である。また、Ｒ₅〜Ｒ₁₀は、それぞれ独立して水素原子、置換もしくは無置換の炭素数１〜１２のアルキル基、置換もしくは無置換の炭素数１〜６のフルオロアルキル基、及び炭素数１〜６のポリフルオロアルキル基、から選ばれる原子または基を示す。）。

(However, in the general formula (2), n is 0 to 2 integer. Also, R ₅ to R ₁₀ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl having 1 to 12 carbon atoms An atom or group selected from a group, a substituted or unsubstituted fluoroalkyl group having 1 to 6 carbon atoms, and a polyfluoroalkyl group having 1 to 6 carbon atoms.

In the compound represented by the general formula (2), n is preferably 0 or 1 from the viewpoints of stability of the compound, ease of synthesis of the compound, solubility in a solvent, price, and the like, and R _{5 to} R ₁₀ Are preferably each independently an atom or group selected from a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and a polyfluoroalkyl group having 1 to 5 carbon atoms. A hydrogen atom or a polyfluoroalkyl group having 1 to 5 carbon atoms is more preferable. More preferably, all of R _{5 to} R ₁₀ are hydrogen atoms, or one or two of R _{5 to} R ₁₀ are polyfluoroalkyl groups having 1 to 5 carbon atoms, and the other is a hydrogen atom. As said C1-C5 polyfluoroalkyl group, a trifluoromethyl group is preferable.

  Specifically, 1,3-propane sultone (1,3-PS), α-trifluoromethyl-γ-sultone, β-trifluoromethyl-γ-sultone, γ-trifluoromethyl-γ-sultone, α -Methyl-γ-sultone, α, β-di (trifluoromethyl) -γ-sultone, α, α-di (trifluoromethyl) -γ-sultone, α-undecafluoropentyl-γ-sultone, α- Examples include heptafluoropropyl-γ-sultone and 1,4-butane sultone (1,4-BS).

  Among these, 1,3-propane sultone (1,3-PS) is considered to form a decomposition film on the negative electrode of a lithium ion secondary battery. 1,3-PS has a LUMO of 0.07 eV. It is larger than that of 1 (−0.86 eV). For example, compound no. When 1 and 1,3-PS were added to the electrolyte and charged, compound No. 1 was first prepared. One substance may form a film on the negative electrode, and then 1,3-PS forms a film. At the initial stage of charging, a portion having a negative electrode surface and compound No. 1 reacts mainly, but compound no. 1 progresses to charge at the part that did not react with 1 (the part that may react with the solvent molecule) and reacts with 1,3-PS. A composite film of 1 and 1,3-PS is formed, and a further resistance increase suppressing effect, battery swelling expansion, and the like can be expected.

  When the compound of the general formula (2) is added to the electrolytic solution, the content in the electrolytic solution is not particularly limited, but 1.0% by mass to 10.0% by mass is included in the electrolytic solution. Is preferred. If it is less than 1.0% by mass, the effect may not be sufficiently exerted on the formation of a film by an electrochemical reaction on the electrode surface at a high temperature. If it exceeds 10.0 mass%, the viscosity of the electrolytic solution may be increased. Moreover, as a ratio of the general formula (2) in the compound of the general formula (1) and the general formula (2), the total mass of the compound of the general formula (1) and the compound of the general formula (2), respectively. 10 to 90% by mass is preferable.

  Examples of the cyclic sulfonic acid ester having two sulfonyl groups include compounds represented by the following general formula (3).

（但し、上記一般式（３）において、Ｑは酸素原子、メチレン基または単結合、Ａは、置換もしくは無置換の炭素数１〜５のアルキレン基、カルボニル基、スルフィニル基、炭素数１〜５のポリフルオロアルキレン基、置換もしくは無置換の炭素数１〜５のフルオロアルキレン基、置換もしくは無置換の炭素数１〜５のアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、炭素数１〜５のポリフルオロアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、及び置換もしくは無置換の炭素数１〜５のフルオロアルキレン基におけるＣ−Ｃ結合の少なくとも一箇所がＣ−Ｏ−Ｃ結合となった基、から選ばれる基を示す。Ｂは、置換もしくは無置換の炭素数１〜５のアルキレン基、炭素数１〜５のポリフルオロアルキレン基、及び置換もしくは無置換の炭素数１〜５のフルオロアルキレン基から選ばれる基を示す。）。

(However, in the said General formula (3), Q is an oxygen atom, a methylene group, or a single bond, A is a substituted or unsubstituted C1-C5 alkylene group, a carbonyl group, a sulfinyl group, C1-C5. At least one C—C bond in the polyfluoroalkylene group, a substituted or unsubstituted fluoroalkylene group having 1 to 5 carbon atoms, or a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms is a C—O—C bond A group in which at least one C—C bond in the polyfluoroalkylene group having 1 to 5 carbon atoms is a C—O—C bond, and a substituted or unsubstituted fluoroalkylene having 1 to 5 carbon atoms A group selected from a group in which at least one CC bond in the group is a C—O—C bond, B is a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, carbon 1-5 polyfluoroalkylene group, and a substituted or unsubstituted group selected from fluoroalkylene group having 1 to 5 carbon atoms.).

  In the compound represented by the general formula (3), A is a substituted or unsubstituted carbon number of 1 to 5 from the viewpoints of stability of the compound, ease of synthesis of the compound, solubility in a solvent, price, and the like. At least a C-C bond in the alkylene group, a polyfluoroalkylene group having 1 to 5 carbon atoms, a substituted or unsubstituted fluoroalkylene group having 1 to 5 carbon atoms, and a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms. A group in which one site is a C—O—C bond, a group in which at least one C—C bond in a C 1-5 polyfluoroalkylene group is a C—O—C bond, and a substituted or unsubstituted group A group selected from a group in which at least one C—C bond in the fluoroalkylene group having 1 to 5 carbon atoms is a C—O—C bond is preferable. A group selected from a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, a polyfluoroalkylene group having 1 to 5 carbon atoms, and a substituted or unsubstituted fluoroalkylene group having 1 to 5 carbon atoms is more preferable. Alternatively, an unsubstituted alkylene group having 1 to 5 carbon atoms is more preferable, and a methylene group, an ethylene group, or a 2,2-propanediyl group is particularly preferable. The C1-C5 fluoroalkylene group preferably includes a methylene group and a difluoromethylene group, and more preferably includes a methylene group and a difluoromethylene group.

  For the same reason, B is preferably an alkylene group having 1 to 5 carbon atoms, more preferably a methylene group, a 1,1-ethanediyl group, or a 2,2-propanediyl group.

  The cyclic sulfonic acid ester having two of these sulfonyl groups is disclosed in Patent Document 10. Specific compounds represented by the general formula (3) are listed below, but are not limited thereto.

これらの化合物は本発明の一般式（１）の化合物と同準位のＬＵＭＯを有し、且つスルホニル基を二つ以上有するため、例えば化合物Ｎｏ．１と化合物Ｎｏ．２１（ＭＭＤＳ）の物質とを電解液に添加すると、充電初期に高イオン伝導性の複合皮膜が形成され易い。ＭＭＤＳは環状の化合物であり開環することで負極と反応し皮膜を形成しやすい化合物であると考えられる。

These compounds have the same level of LUMO as the compound of the general formula (1) of the present invention and have two or more sulfonyl groups. 1 and compound no. When 21 (MMDS) is added to the electrolyte, a high ion conductive composite film is easily formed in the initial stage of charging. MMDS is considered to be a compound that easily forms a film by reacting with the negative electrode by ring opening.

  If MMDS contributes to the film formation fairly selectively on the negative electrode, compound no. In the case of the first material, the film formation probability on the negative electrode is decreased, the reaction probability on the positive electrode is increased, and the film formation on the positive electrode is achieved. As a result, suppression of solvent decomposition on the positive electrode can be expected.

  When the compound of the general formula (3) is added to the electrolytic solution, the content of the compound of the general formula (3) in the electrolytic solution is not particularly limited, but 1.0% by mass or more and 10. It is preferable that 0 mass% or less is contained. If it is less than 1.0% by mass, the effect may not be sufficiently exerted on the formation of a film by an electrochemical reaction on the electrode surface at a high temperature. If it exceeds 10.0 mass%, the viscosity of the electrolytic solution may be increased. As a ratio of the compound of general formula (3) in general formula (1) and general formula (3), 10-90 mass% of the total mass of the compound of general formula (1) and general formula (3) is preferable. . Moreover, when using the compound of General formula (2) in addition to this, 10-90 mass% of the total mass of the compound of General formula (1), General formula (2), and General formula (3) is preferable.

  The electrolytic solution of the present invention is brought about by adding and dissolving the compound represented by the general formula (1) in the electrolytic solution in advance. By appropriately adding other additive materials (cyclic monosulfonic acid ester, cyclic sulfonic acid ester having two sulfonyl groups, sulfolane, alkanesulfonic acid anhydride, sulfolene compound or vinylene carbonate compound) to this electrolytic solution, The electrolyte solution can be obtained.

  The shape of the secondary battery according to the present invention is not particularly limited, and examples thereof include a cylindrical shape, a square shape, a coin shape, and a laminate shape. Among them, the laminate type has a shape sealed by an exterior body made of a flexible film made of a laminate of a synthetic resin and a metal foil, and is a battery can such as a cylindrical type, a square type, or a coin type. It is more susceptible to an increase in internal pressure than that enclosed in an outer package, and therefore control of the chemical reaction between the electrode and the interface between the electrolytic solution is more important. In the case of a secondary battery containing a chain disulfone compound represented by the general formula (1) according to the present invention, even a laminate-type battery can suppress resistance increase and battery swelling (gas generation and internal pressure increase). ) Can be suppressed. Therefore, safety and long-term reliability can be ensured even in a large-sized lithium ion secondary battery such as an automobile.

  In the lithium secondary battery according to the present invention, the negative electrode 13 and the positive electrode 12 are laminated via the separator 16 in a dry air or an inert gas atmosphere, or the laminated one is wound, and then inserted into the outer package. It is obtained by impregnating an electrolytic solution containing a compound represented by the formula (1) and then sealing the battery outer package. The effect of the present invention can be obtained by forming the film on the electrode by charging the battery before or after sealing.

  Moreover, the chain | strand-shaped disulfonic acid ester shown by General formula (1) of this invention can also be used not only as a lithium secondary battery but as an additive of the electrolyte solution for other electrochemical devices. Examples of other electrochemical devices include organic radical batteries, capacitors, and dye-sensitized wet solar cells.

(Production of battery)
A positive electrode active material and a conductivity-imparting agent described in Tables 1 to 3 were dry-mixed and uniformly dispersed in N-methyl-2-pyrrolidone (NMP) in which PVDF as a binder was dissolved to prepare a slurry. Carbon black was used as the conductivity imparting agent. The slurry was applied on an aluminum metal foil (25 μm) serving as a positive electrode current collector, and then NMP was evaporated to obtain a positive electrode sheet. The solid content ratio in the positive electrode was positive electrode active material: conductivity imparting agent: PVDF = 80: 10: 10 (mass%).

  On the other hand, when the negative electrode active material is a carbon material, it is mixed so as to have a ratio of carbon: PVDF = 90: 10 (mass%), and dispersed in NMP, on the copper foil (20 μm) that becomes the negative electrode current collector 14. It was prepared by coating.

As the electrolyte solution 15, a solvent described in Tables 1 to 3, 1 mol / L LiPF ₆ as an electrolyte, and an additive described in Tables 1 to 3 were used.

  Thereafter, the negative electrode and the positive electrode were laminated in a number that gives a rated capacity of 1.7 Ah through a separator 16 made of polyethylene, to produce an aluminum laminated film type secondary battery. The used laminate film has a structure in which a polypropylene resin (sealing layer, thickness 70 μm), polyethylene terephthalate (20 μm), aluminum (50 μm), and polyethylene terephthalate (20 μm) are laminated in this order. Two pieces of this are cut into a predetermined size, and a concave portion having a bottom surface portion and a side surface portion that match the size of the multilayer electrode body is formed in a part thereof, and these are opposed to wrap the multilayer electrode body. Then, the periphery was thermally fused to produce a film-clad battery. Before the last side was heat-sealed and sealed, the electrolyte solution was impregnated with the laminated electrode body.

(conditioning)
Constant current and constant voltage charging is performed for 8 hours at a predetermined temperature (charge temperature) described in Tables 1 to 3 at a charge rate of 0.2 C and a charge end voltage of 4.3 V, a discharge rate of 0.2 C and a discharge end voltage of 2.5 V. Was discharged. Next, constant current and constant voltage charging was performed at a predetermined temperature shown in Tables 1 to 3 at a charge rate of 1 C and a charge end voltage of 4.3 V. Thereafter, a hole was made in the film exterior, the gas generated in the aluminum laminate film was removed, and the opened hole was heat sealed. Thereafter, after storage at 40 ° C. for 7 days, discharge was performed at a discharge rate of 0.2 C and a discharge end voltage of 2.5 V. After the secondary battery was conditioned in this manner, the following storage characteristic test was conducted.

(Storage characteristics test)
The battery was charged at a predetermined temperature (charging temperature) shown in Tables 1 to 3 at a constant current and a constant voltage of 2 A for 5 hours to a final voltage of 4.3 V, and then discharged to a final voltage of 2.5 V under a constant current of 2 A. . The discharge capacity (initial capacity) at this time was measured, and the generated gas was removed to measure the volume of the battery at this time. Then, after charging for 2.5 hours to 4.2 V at a constant current and constant voltage of 2 A at 25 ° C., the battery was discharged to a discharge depth of 50% and then left at 55 ° C. for 100 days. After leaving, the discharge operation was performed again at a predetermined current described in Tables 1 to 3 at a constant current. Subsequently, the charge and discharge were repeated again at the same constant current, and the discharge capacity at this time was defined as a recovery capacity. Here, (capacity recovery rate) = (recovery capacity) / (initial capacity). At the same time, the volume of the battery was measured, and the difference from the volume immediately after degassing was taken as the cell volume change amount.

  At the same time, the voltage was measured on the 7th day from the start of standing and the voltage drop due to storage was measured, and (value of the dropped voltage) / 7 was defined as “voltage drop during storage for 7 days”. Furthermore, after charging for 2.5 hours to 4.2 V at a constant current and constant voltage of 2 A at 25 ° C. as described above, after discharging to a discharge depth of 50%, charging and discharging are performed for 10 seconds at 1C, 3C, and 7C. The slope in which the current and the voltage immediately before the end of charging / discharging for 10 seconds are plotted is defined as the DC resistance.

表１〜３中の「電解液中の添加剤の種類及び含量」欄記載の「Ｎｏ．」は化合物Ｎｏ．を表す。また、（ ）の中の数字は電解液中の含量を表す。

In Tables 1 to 3, “No.” in the column “Type and content of additives in electrolytic solution” is “No. Represents. The number in () represents the content in the electrolyte.

  Tables 4 to 6 below show the voltage drop that occurs during storage for 7 days at 40 ° C. at the beginning of the storage characteristic test and the results obtained in the storage test.

（一般式（１）の化合物を含む電解液の充電温度の効果）
実施例１〜３（表４）における電圧降下、容量回復率、セル体積変化量をそれぞれ、比較例１〜１２（表６）と比較すると、実施例１〜３においては電圧降下の抑制、セル体積変化量及び容量回復率等において飛躍的な改善が確認された。これらの結果より、充電温度を高めることにより一般式（１）の電極表面上での皮膜形成反応を促進し、電解液成分の分解等をより抑制することができたものと考えられる。

(Effect of charging temperature of electrolyte solution containing compound of general formula (1))
When the voltage drop, the capacity recovery rate, and the cell volume change amount in Examples 1 to 3 (Table 4) are respectively compared with Comparative Examples 1 to 12 (Table 6), suppression of the voltage drop and the cell in Examples 1 to 3 are shown. Significant improvements in volume change and capacity recovery rate were confirmed. From these results, it is considered that by increasing the charging temperature, the film formation reaction on the electrode surface of the general formula (1) was promoted, and the decomposition of the electrolyte component and the like could be further suppressed.

(Effect of charging temperature)
In Examples 1 to 15 and Comparative Examples 1 to 12, Compound No. For the 1, 2, and 16 chain sulfonic acid compounds, charging / discharging was performed while changing the charging temperature, and the influence of the charging temperature on the battery characteristics was evaluated. As a result, it was confirmed that by setting the charging temperature to 30 ° C. or more and 60 ° C. or less, an excellent effect on storage characteristics (suppression of voltage drop, DC resistance, capacity recovery rate, cell volume change amount) can be obtained ( Tables 4 and 6). Moreover, these characteristic values were further improved by setting the charging temperature to 40 ° C. or higher and 55 ° C. or lower. From the above results, it was confirmed that the charging temperature is preferably 30 ° C. or higher and 60 ° C. or lower, and the particularly preferable temperature range is 40 ° C. or higher and 55 ° C. or lower.

(Influence of concentration of compound of general formula (1) in electrolyte)
In Example 1 and Examples 17 to 20 and Reference Examples 1 to 3 , Compound No. A secondary battery was prepared by changing the concentration in 1 of the electrolytic solution, and its characteristics were evaluated. As a result, the storage characteristics are as follows. It was found that when 1 concentration was 0.1% by mass or more and 5.0% by mass or less, an excellent effect was obtained (Tables 4 and 5). From this result, it was confirmed that the concentration of the compound of the general formula (1) in the electrolytic solution is preferably 0.1% by mass or more and 5.0% by mass or less.

(Effect of addition of cyclic monosulfonic acid ester in laminated film type battery)
The cell volume change amount in Example 23 and Example 24 is smaller than that in Comparative Example 14, Comparative Example 15, and Example 1. This is presumably because a film was formed on the negative electrode due to the combined effect of the compound (1) and 1,3-PS or 1,4-BS, and gas generation due to decomposition of the electrolyte was greatly suppressed.

(Effect of addition of cyclic sulfonic acid ester having two sulfonyl groups)
The voltage drop in Example 25 is further improved as compared with Example 1 and Comparative Examples 16 and 17. These results are obtained by adding the compound represented by the general formula (1) of the present invention and a cyclic sulfonic acid ester having two sulfonyl groups to the electrolytic solution, and increasing the charging temperature. This is considered to be because a film having high ion conductivity and high stability during storage was formed as compared with the additive system. The volume change amount of the cell in Example 25 is smaller than those in Comparative Examples 16 and 17 and Example 1. This is compound no. This is probably because a film was formed on the negative electrode due to the combined effect of No. 1 and MMDS, and gas generation due to decomposition of the electrolytic solution was greatly suppressed.

It is a schematic block diagram of the secondary battery which concerns on this invention.

Explanation of symbols

11 Positive Electrode Current Collector 12 Layer Containing Positive Electrode Active Material 13 Layer Containing Negative Electrode Active Material 14 Negative Electrode Current Collector 15 Nonaqueous Electrolyte Solution 16 Porous Separator

Claims (7)

A charge / discharge method of a non-aqueous electrolyte secondary battery having an electrolyte solution containing at least an aprotic solvent in which an electrolyte is dissolved and a compound represented by the following general formula (1):
A compound represented by the following general formula (1) is contained in the electrolyte solution at a content of 0.1 to 5.0% by mass,
Discharge method of the nonaqueous electrolyte secondary battery temperature of the nonaqueous electrolyte secondary battery charged and performing in the range of 30 to 60 ° C..

(However, in the above general formula (1), .R ₂ and R ₃ R ₁ and R ₄ represents a water MotoHara child are each independently, -OCH _3, -OCH ₂ CH ₃ and -OC ₆ H indicating the selected Ru group from _5.) Discharge method of the non-aqueous electrolyte secondary battery according to claim 1, the charging temperature of the nonaqueous electrolyte secondary battery and performing in the range of 40 to 55 ° C..   The charging / discharging method for a non-aqueous electrolyte secondary battery according to claim 1, wherein the charging is charging of a non-aqueous electrolyte secondary battery in an initial state.   The charge / discharge method for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein an end-of-charge voltage at the time of charging is 3.4 V or more. 5. The ratio C _d / C _c between the discharge capacity C _d at the time of discharge and the charge capacity C _c at the time of charge is 0.5 to 0.95, according to claim 1. The charge / discharge method of the nonaqueous electrolyte secondary battery as described. The electrolyte further charging of the nonaqueous electrolyte secondary battery according to any one of claim 1 to 5, characterized in that it comprises a cyclic monosulfonic acid ester represented by the following general formula (2) Discharge method.

(However, in the general formula (2), n is 0 to 2 integer. Also, R ₅ to R ₁₀ are each independently hydrogen atom, an unsubstituted alkyl group having 1 to 12 carbon atoms And an atom or group selected from an unsubstituted fluoroalkyl group having 1 to 6 carbon atoms and a polyfluoroalkyl group having 1 to 6 carbon atoms.) The electrolyte is non-aqueous charge and discharge process of the electrolytic solution secondary battery according to any one of claim 1 to 6, further comprising a methylene methane disulfonic acid ester.

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