Electrolyte compositions, electrochemical devices, secondary batteries, and lithium-ion secondary batteries

Abstract

Provided are an electrolyte solution composition that can suppress gas generation during high-temperature storage, and an electrochemical device, a secondary battery, and a lithium-ion secondary battery that use the electrolyte solution composition. The present invention provides a composition for an electrolyte solution, which contains a compound (A) represented by the following formula (A): (A)Rf 1 -O-CH2-CH2-OR 1 (In the formula, Rf 1 is a fluoroalkyl group having 1 to 6 carbon atoms, and R 1 is H, Li, Na, K or Cs.

Description

[Technical Field]

[0001] This disclosure relates to electrolyte compositions, electrochemical devices, secondary batteries, and lithium-ion secondary batteries. [Background technology]

[0002] In recent years, with the trend towards lighter and smaller electrical products, the development of electrochemical devices such as lithium-ion secondary batteries with high energy density has been progressing. Furthermore, as the application fields of electrochemical devices such as lithium-ion secondary batteries expand, there is a growing demand for improved characteristics. In particular, if lithium-ion secondary batteries are to be used in automobiles in the future, improving battery characteristics will become increasingly important.

[0003] Patent Document 1 describes an electrolyte for a lithium metal secondary battery containing a specific lithium salt and a non-aqueous solvent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2022-552481 [Overview of the project] [Problems that the invention aims to solve]

[0005] This disclosure aims to provide an electrolyte composition that can suppress gas generation during high-temperature storage, as well as an electrochemical device, a secondary battery, and a lithium-ion secondary battery using the electrolyte composition. [Means for solving the problem]

[0006] This disclosure (1) is an electrolyte composition containing compound (A) represented by the following formula (A). (A)Rf 1 -O-CH2-CH2-OR 1 (In the formula, Rf 1is a fluoroalkyl group having 1 to 6 carbon atoms, and R 1 is H, Li, Na, K or Cs.)

[0007] This disclosure (2) is the composition for an electrolyte according to the above-mentioned Rf 1 is HCF2-CF2-, HCF2-CF2-CH2-, HCF2-CH2-, CF3-CF2-CH2-, or CF3-CHF-CF2- and is the composition for an electrolyte according to the above-mentioned disclosure (1).

[0008] This disclosure (3) is the composition for an electrolyte according to the above-mentioned disclosure (1) or (2) where R 1 is H or Li.

[0009] This disclosure (4) is the composition for an electrolyte according to any one of the above-mentioned disclosures (1) to (3), where the content of the above-mentioned compound (A) is 0.0001 to 30000 ppm with respect to the composition for an electrolyte.

[0010] This disclosure (5) is that the above-mentioned compound (A) is HCF2-CF2-O-CH2-CH2-OH, HCF2-CF2-O-CH2-CH2-OLi, CF3-CHF-CF2-O-CH2-CH2-OH, and CF3-CHF-CF2-O-CH2-CH2-OLi, and is the composition for an electrolyte according to any one of the above-mentioned disclosures (1) to (4).

[0011] This disclosure (6) is the composition for an electrolyte according to any one of the above-mentioned disclosures (1) to (5), which contains a fluorinated ether (E) represented by the following formula (E). (E) Rf 2 -O-R 2 (In the formula, Rf 2 is a fluoroalkyl group having 1 to 5 carbon atoms, and R 2 is H or an alkyl group having 1 to 6 carbon atoms. R2 The alkyl group may have an ether linkage and / or fluorine.

[0012] This disclosure (7) refers to the aforementioned Rf 2 This is the electrolyte composition described in (6) of this disclosure, which is HCF2-CF2-.

[0013] This disclosure (8) refers to the R 2 teeth, -CH2-CH2-O-CF2-CF2H, or, -CH2-CH2-O-CF2-CHF-CF3 This is the electrolyte composition described in (6) or (7) of this disclosure.

[0014] This disclosure (9) states that the fluorinated ether (E) is HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, and, CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3 The electrolyte composition is one of any (6) to (8) of this disclosure, which is selected from the group consisting of the above.

[0015] Disclosure (10) is an electrolyte composition according to any one of Disclosures (6) to (9), wherein the content of the fluorinated ether (E) is 0.01 to 99% by mass with respect to the electrolyte composition.

[0016] Disclosure (11) is an electrolyte composition according to any one of Disclosures (1) to (10) that contains at least one lithium salt selected from the group consisting of LiPF6, LiFSI, and LiTFSI.

[0017] This disclosure (12) states that the compound (A) is HCF2-CF2-O-CH2-CH2-OH, HCF2-CF2-O-CH2-CH2-OLi, CF3-CHF-CF2-O-CH2-CH2-OH, and, It is at least one selected from the group consisting of CF3-CHF-CF2-O-CH2-CH2-OLi, The content of compound (A) is 0.003 to 30000 ppm relative to the electrolyte composition. HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, and, CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3 It comprises at least one fluorinated ether (E) selected from the group consisting of the following, The electrolyte composition according to any one of the disclosures (1) to (11) wherein the content of the fluorinated ether (E) is 0.5 to 50% by mass relative to the electrolyte composition.

[0018] The present disclosure (13) relates to the electrolyte composition described in the present disclosure (12), and a secondary battery containing lithium metal as a negative electrode active material.

[0019] This disclosure (14) states that compound (A) is HCF2-CF2-O-CH2-CH2-OH, HCF2-CF2-O-CH2-CH2-OLi, CF3-CHF-CF2-O-CH2-CH2-OH, and, It is at least one selected from the group consisting of CF3-CHF-CF2-O-CH2-CH2-OLi, The content of compound (A) is 0.01 to 30000 ppm relative to the electrolyte composition. HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, and, CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3 It comprises at least one fluorinated ether (E) selected from the group consisting of the following, The electrolyte composition according to any one of the disclosures (1) to (11) wherein the content of the fluorinated ether (E) is 40 to 95% by mass relative to the electrolyte composition.

[0020] The present disclosure (15) relates to the electrolyte composition described in the present disclosure (14), and a secondary battery comprising a silicon material as a negative electrode active material.

[0021] Disclosure (16) is an electrolyte composition according to any of Disclosures (1) to (12) or (14) for use in secondary batteries.

[0022] Disclosure (17) is an electrochemical device comprising an electrolyte composition as described in any of Disclosures (1) to (12) or (14).

[0023] Disclosure (18) is a secondary battery comprising an electrolyte composition as described in any of Disclosures (1) to (12) or (14).

[0024] Disclosure (19) is a lithium-ion secondary battery comprising an electrolyte composition as described in any of Disclosures (1) to (12) or (14). [Effects of the Invention]

[0025] According to this disclosure, it is possible to provide an electrolyte composition that can suppress gas generation during high-temperature storage, as well as an electrochemical device, a secondary battery, and a lithium-ion secondary battery using the electrolyte composition. [Modes for carrying out the invention]

[0026] The following provides a detailed explanation of this disclosure.

[0027] This disclosure relates to an electrolyte composition containing compound (A) represented by the following formula (A). (A)Rf 1 -O-CH2-CH2-OR 1 (In the formula, Rf 1 R is a fluoroalkyl group having 1 to 6 carbon atoms. 1 (These are H, Li, Na, K, or Cs.)

[0028] The composition of this disclosure, by containing compound (A), can suppress gas generation during high-temperature storage in electrochemical devices. This effect is presumed to be brought about by the suppression of side reactions at the cathode / electrolyte interface by adsorption of compound (A) to defective areas of the cathode.

[0029] The compositions disclosed herein are used in electrolytes, and may be electrolytes or components (additives, etc.) of electrolytes. Furthermore, the compositions of this disclosure can be suitably used in electrochemical devices (particularly secondary batteries such as lithium-ion secondary batteries).

[0030] In formula (A), Rf 1 These are fluoroalkyl groups with 1 to 6 carbon atoms. The number of carbon atoms in the above fluoroalkyl group is preferably 1 to 4, more preferably 1 to 3, even more preferably 2 to 3, and particularly preferably 2. The above fluoroalkyl group may be linear or branched, but it is preferably linear. Rf 1 Preferably, HCF2-CF2-, HCF2-CF2-CH2-, HCF2-CH2-, CF3-CF2-CH2-, and CF3-CHF-CF2- are used, with HCF2-CF2- and CF3-CHF-CF2- being more preferred from the viewpoint of suppressing gas generation during high-temperature storage.

[0031] In formula (A), R 1 The elements are H, Li, Na, K, or Cs. From the viewpoint of suppressing gas generation during high-temperature storage, H, Li, Na, and K are preferred, and H and Li are more preferred.

[0032] Among the compounds (A), in particular, from the standpoint of suppressing gas generation during high-temperature storage, HCF2-CF2-O-CH2-CH2-OH, HCF2-CF2-CH2-O-CH2-CH2-OH, HCF2-CH2-O-CH2-CH2-OH, CF3-CF2-CH2-O-CH2-CH2-OH, CF3-CHF-CF2-O-CH2-CH2-OH, CF3-CHF-CF2-O-CH2-CH2-OLi, HCF2-CF2-O-CH2-CH2-OLi, HCF2-CF2-O-CH2-CH2-OK, This is preferable, HCF2-CF2-O-CH2-CH2-OH, HCF2-CF2-O-CH2-CH2-OLi, CF3-CHF-CF2-O-CH2-CH2-OH, CF3-CHF-CF2-O-CH2-CH2-OLi, More preferable, HCF2-CF2-O-CH2-CH2-OH, CF3-CHF-CF2-O-CH2-CH2-OH, That is even more preferable.

[0033] Compound (A) may be used alone or in combination of two or more types.

[0034] In the compositions of the present disclosure, the content of compound (A) is preferably 0.0001 ppm or more and 30,000 ppm or less relative to the composition of the present disclosure. In terms of further suppressing gas generation during high-temperature storage, the content of compound (A) is more preferably 0.003 ppm or more, even more preferably 0.01 ppm or more, particularly preferably 0.1 ppm or more, more preferably 20,000 ppm or less, even more preferably 10,000 ppm or less, even more preferably 7,000 ppm or less, and particularly preferably 5,000 ppm or less, relative to the composition of the present disclosure.

[0035] The compositions of this disclosure preferably contain a fluorinated ether (E) represented by the following formula (E). (E)Rf 2 -OR 2 (In the formula, Rf 2 R is a fluoroalkyl group having 1 to 5 carbon atoms. 2R is either H or an alkyl group having 1 to 6 carbon atoms. 2 The alkyl group may have an ether linkage and / or fluorine.

[0036] By using compound (A) and fluorinated ether (E) in combination, gas generation during high-temperature storage can be further suppressed. This effect is presumed to be brought about by the suppression of side reactions at the cathode / electrolyte interface due to the high oxidation resistance of fluorinated ether (E) and the adsorption of compound (A) to the cathode.

[0037] In formula (E), Rf 2 These are fluoroalkyl groups with 1 to 6 carbon atoms. The number of carbon atoms in the above fluoroalkyl group is preferably 1 to 4, more preferably 1 to 3, even more preferably 1 to 2, and particularly preferably 2. The above fluoroalkyl group may be linear or branched, but it is preferably linear. Rf 2 Preferably, the following are used: CF3-, CF2H-, CFH2-, CF3-CF2-, CF3-CH2-, HCF2-CH2-, HCF2-CF2-, FCH2-CH2-, CF3-CH2-CH2-, CF3-CF2-CH2-, HCF2-CF2-CH2-, FCH2-CF2-CH2-, and HCF2-CF2-CF2-CF2-CH2-, with HCF2-CF2- being more preferred from the viewpoint of suppressing gas generation during high-temperature storage.

[0038] In formula (E), R 2 is either H or an alkyl group having 1 to 6 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 4, more preferably 1 to 3, and even more preferably 3. The alkyl group may be linear or branched, but linear is preferred. The alkyl group may have an ether linkage and / or fluorine, but it is preferred to have an ether linkage and fluorine. R 2Preferably, -CF3, -CF2H, -CFH2, -CH3, -CH2-CH3, -CF2-CF3, -CH2-CF3, -CH2-CF2H, -CH2-CFH2, -CH2-CH2-CH3, -CH2-CH2-CF3, -CH2-CF2-CF3, -CH2-CF2-CF2H, -CH2-CF2-CFH2, -CH2-CF2-CF2-CF2-CF2H, -CH2-CH2-O-CF2-CF2H, and -CH2-CH2-O-CF2-CHF-CF3 are preferred, and -CH2-CH2-O-CF2-CF2H and -CH2-CH2-O-CF2-CHF-CF3 are more preferred from the viewpoint of suppressing gas generation during high-temperature storage.

[0039] Among fluorinated ethers (E), in particular, from the standpoint of suppressing gas generation during high-temperature storage HCF2-CF2-O-CH2-CF2-O-CF2-CF2H, HCF2-CF2-CH2-O-CH2-CH2-CH2-CF2-CF2H, HCF2-CH2-O-CH2-CH2-O-CH2-CF2H, HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, CF3-CF2-CH2-O-CH2-CH2-O-CH2-CF2-CF3, CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3, HCF2-CF2-CH2-O-CF2-CF2H, This is preferable, HCF2-CF2-O-CH2-CH2-O-CF2-CF2H, CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3, This is preferable.

[0040] Fluorinated ether (E) may be used alone or in combination of two or more types. When using two types of fluorinated ether (E) in combination, it is preferable to combine HCF2-CF2-O-CH2-CH2-O-CF2-CF2H and HCF2-CF2-CH2-O-CF2-CF2H.

[0041] In the compositions of this disclosure, the content of fluorinated ether (E) is preferably 0.01% by mass or more and 99% by mass or less relative to the composition of this disclosure. When the composition of the present disclosure is used as a negative electrode active material in a secondary battery containing a silicon material, the content of fluorinated ether (E) is more preferably 10% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, particularly preferably 50% by mass or more, and more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, in order to further suppress gas generation during high-temperature storage. When the composition of the present disclosure is used as a negative electrode active material in a secondary battery containing a metallic material (particularly lithium metal), the content of fluorinated ether (E) is more preferably 0.5% by mass or more, even more preferably 2% by mass or more, even more preferably 10% by mass or more, particularly preferably 20% by mass or more, and more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less, in order to further suppress gas generation during high-temperature storage.

[0042] In the compositions of this disclosure, the content of compound (A) is preferably 0.00000001% by mass or more and 5% by mass or less, relative to the content of fluorinated ether (E). When the composition of this disclosure is used as a negative electrode active material in a secondary battery containing a silicon material, the content of compound (A) is more preferably 0.0000001% by mass or more, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.06% by mass or less, and particularly preferably 0.03% by mass or less, relative to the content of fluorinated ether (E), in order to further suppress gas generation during high-temperature storage. When the composition of this disclosure is used as a negative electrode active material in a secondary battery containing a metallic material (particularly lithium metal), the content of compound (A) is more preferably 0.00000003% by mass or more, even more preferably 0.0000003% by mass or more, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.05% by mass or less, relative to the content of fluorinated ether (E), in order to further suppress gas generation during high-temperature storage.

[0043] The compositions of this disclosure preferably contain a solvent. A fluorinated ether (E) may be used as the solvent, but other solvents may also be included.

[0044] The above solvent preferably contains at least one selected from the group consisting of carbonates and carboxylic acid esters.

[0045] The above-mentioned carbonate may be a cyclic carbonate or a chain carbonate.

[0046] The above-mentioned cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0047] Examples of the above-mentioned non-fluorinated cyclic carbonates include non-fluorinated saturated cyclic carbonates, with non-fluorinated saturated alkylene carbonates having alkylene groups with 2 to 6 carbon atoms being preferred, and non-fluorinated saturated alkylene carbonates having alkylene groups with 2 to 4 carbon atoms being more preferred.

[0048] In particular, as the non-fluorinated saturated cyclic carbonate, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, cis-2,3-pentylene carbonate, cis-2,3-butylene carbonate, 2,3-pentylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,2-butylene carbonate, and butylene carbonate is preferred because it has a high dielectric constant and suitable viscosity.

[0049] The above-mentioned non-fluorinated saturated cyclic carbonates may be used individually or in combination of two or more in any combination and ratio.

[0050] If the above-mentioned non-fluorinated saturated cyclic carbonate is included, the content of the above-mentioned non-fluorinated saturated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume relative to the above-mentioned solvent.

[0051] The above-mentioned fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. Solvents containing fluorinated cyclic carbonates can be suitably used even under high voltage. In this specification, "high voltage" refers to a voltage of 4.2V or higher. The upper limit of "high voltage" is preferably 5.5V, and more preferably 5.0V.

[0052] The above-mentioned fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0053] The above-mentioned fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, and specifically, the following general formula (A):

[0054] [ka] (In the formula, X 1 ~X 4The same or different, each representing -H, -CH3, -C2H5, -F, a fluorinated alkyl group which may have an ether linkage, or a fluorinated alkoxy group which may have an ether linkage. However, X 1 ~X 4 At least one of the members is -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond. Examples of compounds represented by ) are the above fluorinated alkyl groups such as -CF3, -CF2H, and -CH2F.

[0055] When the composition of this disclosure includes the above-mentioned fluorinated saturated cyclic carbonate, the oxidation resistance of the electrolyte is improved when the composition is applied to a high-voltage lithium-ion secondary battery or the like, resulting in stable and excellent charge-discharge characteristics. In this specification, "ether bond" refers to a bond represented by -O-.

[0056] Due to its good dielectric constant and oxidation resistance, X 1 ~X 4 Preferably, one or two of these are -F, a fluorinated alkyl group which may have an ether linkage, or a fluorinated alkoxy group which may have an ether linkage.

[0057] Because it is expected to reduce viscosity at low temperatures, increase the flash point, and further improve the solubility of the electrolyte salt, X 1 ~X 4 Preferably, the element is -H, -F, a fluorinated alkyl group (a), a fluorinated alkyl group having an ether linkage (b), or a fluorinated alkoxy group (c).

[0058] The above-mentioned fluorinated alkyl group (a) is obtained by substituting at least one hydrogen atom of the alkyl group with a fluorine atom. The number of carbon atoms in the fluorinated alkyl group (a) is preferably 1 to 20, more preferably 1 to 17, even more preferably 1 to 7, and particularly preferably 1 to 5. If the carbon number is too large, the low-temperature characteristics may deteriorate, or the solubility of the electrolyte salt may decrease. If the carbon number is too small, the solubility of the electrolyte salt may decrease, the discharge efficiency may decrease, and further, the viscosity may increase.

[0059] Among the fluorinated alkyl groups (a) above, those with 1 carbon atom include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- is preferable in terms of high-temperature storage characteristics, and CF3- is most preferable.

[0060] Among the fluorinated alkyl groups (a) above, those with 2 or more carbon atoms include the following general formula (a-1): R a1 -R a2 - (a-1) (In the formula, R a1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R a2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; provided that at least one of R a1 and R a2 has a fluorine atom) The fluorinated alkyl group represented by is preferably exemplified in terms of good solubility of the electrolyte salt. Note that R a1 and R a2 may further have other atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0061] R a1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. As R a1 , a linear or branched alkyl group having 1 to 16 carbon atoms is preferable. The carbon number of R a1 is more preferably 1 to 6, and even more preferably 1 to 3.

[0062] R a1 Specifically, as a linear or branched alkyl group, CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0063]

Chemical formula

[0064] include the following.

[0065] In addition, when R a1 is a linear alkyl group having a fluorine atom, CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CH2CH2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CH2CH2CH2CH2-, CF3CF2CH2CH2CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc. are included.

[0066] In addition, Ra1 If it is a branched alkyl group having a fluorine atom,

[0067] [ka]

[0068] [ka]

[0069] These are some examples of preferred structures. However, since the presence of CH3- or CF3- branches tends to increase viscosity, it is more preferable that the number of such branches be small (1) or zero.

[0070] R a2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom. a2 The alkylene group may be linear or branched. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below. a2 These are composed of one or a combination of these.

[0071] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0072] (ii) The smallest structural unit of a branched chain:

[0073] [ka]

[0074] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0075] R a2When it is linear, it consists only of the above-mentioned linear minimum structural units, and among them, -CH2-, -CH2CH2- or -CF2- is preferable. From the viewpoint of further improving the solubility of the electrolyte salt, -CH2- or -CH2CH2- is more preferable.

[0076] R a2 When it is branched-chain, it contains at least one of the above-mentioned branched-chain minimum structural units, and those represented by the general formula -(CX a X b )-(X a is H, F, CH3 or CF3; X b is CH3 or CF3. However, when X b is CF3, X a is H or CH3) can be preferably exemplified. These can particularly further improve the solubility of the electrolyte salt.

[0077] Preferred fluorinated alkyl groups (a) include, for example, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CHF-, CH3CF2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0078]

Chemical formula

[0079]

Chemical formula

[0080] [[ID=4I]] and the like can be mentioned.

[0081] The above-mentioned fluorinated alkyl group (b) having an ether linkage is obtained by substituting at least one hydrogen atom of the alkyl group having an ether linkage with a fluorine atom. The above-mentioned fluorinated alkyl group (b) having an ether linkage preferably has 2 to 17 carbon atoms. If the number of carbon atoms is too high, the viscosity of the above-mentioned fluorinated saturated cyclic carbonate will increase, and the number of fluorine-containing groups will increase, which may lead to a decrease in the solubility of the electrolyte salt due to a decrease in dielectric constant and a decrease in compatibility with other solvents. From this viewpoint, the number of carbon atoms of the above-mentioned fluorinated alkyl group (b) having an ether linkage is more preferably 2 to 10, and even more preferably 2 to 7.

[0082] The alkylene group constituting the ether portion of the fluorinated alkyl group (b) having the above ether linkage may be a linear or branched alkylene group. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below.

[0083] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0084] (ii) The smallest structural unit of a branched chain:

[0085] [ka]

[0086] Alkylene groups may consist of these minimum structural units alone, or they may be composed of linear (i) units together, branched (ii) units together, or combinations of linear (i) and branched (ii) units. Preferred specific examples will be described later.

[0087] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0088] A more preferred fluorinated alkyl group having an ether bond is the general formula (b-1): R 3 -(OR 4 ) n1 - (b-1) (In the formula, R 3 R may have a fluorine atom, preferably an alkyl group having 1 to 6 carbon atoms; 4 n1 is an integer from 1 to 3, where R is an alkylene group having 1 to 4 carbon atoms, which may have a fluorine atom; n1 is an integer from 1 to 3; however, 3 and R 4 Examples include those represented by (at least one of which has a fluorine atom).

[0089] R 3 and R 4 Examples include the following, and these can be appropriately combined to form a fluorinated alkyl group (b) having an ether bond represented by the above general formula (b-1), but are not limited to these.

[0090] (1)R 3 For example, the general formula is: X c 3C-(R 5 ) n2 -(3 X c The same or different, both are H or F;R 5 (1) is an alkylene group which may have 1 to 5 carbon atoms and a fluorine atom; n2 is preferably an alkyl group represented as 0 or 1.

[0091] If n2 is 0, R 3 Examples include CH3-, CF3-, HCF2-, and H2CF-.

[0092] A concrete example of the case where n2 is 1 is R 3The linearly chained elements are CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, C F3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF 2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH 2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2C F2CF2CF2CH2CH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, CH3CF2-, CH3CH2-, CH3CF2CH2-, CH3CF2CF2-, CH3CH2CH2-, Examples include CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CH2CH2CH2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CH2CF2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, etc.

[0093] n2 is 1 and R 3 However, as for branched chains,

[0094] [ka]

[0095] These are some examples.

[0096] However, if it has branches such as CH3- or CF3-, the viscosity tends to increase, 3 A linear structure is more preferable.

[0097] (2) -(OR 4 ) n1 -In this case, n1 is an integer between 1 and 3, preferably 1 or 2. Note that when n1 = 2 or 3, R 4 They can be the same or different.

[0098] R 4 Preferred specific examples include the following linear or branched chains.

[0099] Examples of linear molecules include -CH2-, -CHF-, -CF2-, -CH2CH2-, -CF2CH2-, -CF2CF2-, -CH2CF2-, -CH2CH2CH2-, -CH2CH2CF2-, -CH2CF2CH2-, -CH2CF2CF2-, -CF2CH2CH2-, -CF2CF2CH2-, -CF2CH2CF2-, -CF2CF2CF2-, etc.

[0100] As for branched chains,

[0101] [ka]

[0102] These are some examples.

[0103] The above-mentioned fluorinated alkoxy group (c) is obtained by substituting at least one hydrogen atom of the alkoxy group with a fluorine atom. The above-mentioned fluorinated alkoxy group (c) preferably has 1 to 17 carbon atoms. More preferably, it has 1 to 6 carbon atoms.

[0104] The above fluorinated alkoxy group (c) is represented by the general formula: X d 3C-(R 6 ) n3-O-(three Xs d are the same or different and each is H or F; R 6 is preferably an alkylene group which may have a fluorine atom and has 1 to 5 carbon atoms; n3 is 0 or 1; provided that any one of the three Xs d contains a fluorine atom) is particularly preferred as the fluorinated alkoxy group represented by the formula.)

[0105] Specific examples of the fluorinated alkoxy group (c) include a fluorinated alkoxy group in which an oxygen atom is bonded to the terminal of the alkyl group exemplified as R a1 in the above general formula (a-1).

[0106] The fluorine content of the fluorinated alkyl group (a), the fluorinated alkyl group (b) having an ether bond, and the fluorinated alkoxy group (c) in the above fluorinated saturated cyclic carbonate is preferably 10% by mass or more. If the fluorine content is too low, there is a risk that the viscosity reduction effect and the flash point increase effect at low temperatures cannot be obtained sufficiently. From this viewpoint, the fluorine content is more preferably 12% by mass or more, and still more preferably 15% by mass or more. The upper limit is usually 76% by mass. The fluorine content of the fluorinated alkyl group (a), the fluorinated alkyl group (b) having an ether bond, and the fluorinated alkoxy group (c) is a value calculated by {(number of fluorine atoms × 19) / formula weight of each group} × 100 (%) based on the structural formula of each group.

[0107] Also, from the viewpoint of good dielectric constant and oxidation resistance, the fluorine content of the entire fluorinated saturated cyclic carbonate is preferably 10% by mass or more, and more preferably 15% by mass or more. The upper limit is usually 76% by mass. The fluorine content of the fluorinated saturated cyclic carbonate is a value calculated by {(number of fluorine atoms × 19) / molecular weight of the fluorinated saturated cyclic carbonate} × 100 (%) based on the structural formula of the fluorinated saturated cyclic carbonate.

[0108] Specific examples of the fluorinated saturated cyclic carbonate include, for example, the following.

[0109] X 1 ~X 4 Specific examples of fluorinated saturated cyclic carbonates in which at least one of

[0110]

Chem.

[0111] In addition,

[0112]

Chem.

[0113] etc. can also be used.

[0114] X 1 ~X 4 Specific examples of fluorinated saturated cyclic carbonates in which at least one of

[0115]

Chem.

[0116] <00​​​​​​​​​​​​​​​​​​​​​​​​​A specific example of a fluorinated saturated cyclic carbonate in which at least one of the members is a fluorinated alkyl group (b) or a fluorinated alkoxy group (c) having an ether linkage, and the rest are all -H, is:

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] These are some examples.

[0127] In particular, the above-mentioned fluorinated saturated cyclic carbonate is preferably one of the following compounds.

[0128] [ka]

[0129] [ka]

[0130] Other examples of the above-mentioned fluorinated saturated cyclic carbonates include trans-4,5-difluoro-1,3-dioxolan-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-dioxolan-2-one, 4-methylene-1,3-dioxolan-2-one, 4-methyl-5-trifluoromethyl-1,3-dioxolan-2-one, 4-ethyl-5-fluoro-1,3-dioxolan-2-one, and 4-ethyl-5,5-difluoro-1,3- Examples include dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolan-2-one, 4,4-difluoro-5-methyl-1,3-dioxolan-2-one, 4-fluoro-5-methyl-1,3-dioxolan-2-one, 4-fluoro-5-trifluoromethyl-1,3-dioxolan-2-one, and 4,4-difluoro-1,3-dioxolan-2-one.

[0131] Among the above-mentioned fluorinated saturated cyclic carbonates, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethylethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropylethylene carbonate are more preferred.

[0132] The above-mentioned fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom, and fluorinated ethylene carbonate derivatives substituted with substituents having an aromatic ring or a carbon-carbon double bond are preferred. Specifically, examples include 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate.

[0133] The above-mentioned fluorinated cyclic carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0134] If the above-mentioned fluorinated cyclic carbonate is included, the content of the above-mentioned fluorinated cyclic carbonate is preferably 5 to 90% by mass, more preferably 10 to 60% by mass, and even more preferably 15 to 45% by mass relative to the above-mentioned composition.

[0135] The above-mentioned chain-like carbonate may be a non-fluorinated chain-like carbonate or a fluorinated chain-like carbonate.

[0136] Examples of the above-mentioned non-fluorinated linear carbonates include hydrocarbon-based linear carbonates such as CH3OCOOCH3 (dimethyl carbonate: DMC), CH3CH2OCOOCH2CH3 (diethyl carbonate: DEC), CH3CH2OCOOCH3 (ethyl methyl carbonate: EMC), CH3OCOOCH2CH2CH3 (methyl propyl carbonate), methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl isopropyl carbonate, methyl-2-phenylphenyl carbonate, phenyl-2-phenylphenyl carbonate, trans-2,3-pentylene carbonate, trans-2,3-butylene carbonate, and ethylphenyl carbonate. Among these, it is preferable that it be at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate.

[0137] The above-mentioned non-fluorinated linear carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0138] When the above-mentioned non-fluorinated linear carbonate is included, the content of the above-mentioned non-fluorinated linear carbonate is preferably 10 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 80% by mass relative to the above-mentioned composition.

[0139] The above-mentioned fluorinated chain carbonate is a chain carbonate having fluorine atoms. Solvents containing fluorinated chain carbonates can be suitably used even under high voltage.

[0140] The above fluorinated chain carbonate is a general formula (B): Rf 2 OCOOR 7 (B) (In the formula, Rf 2 R is a fluorinated alkyl group having 1 to 7 carbon atoms. 7This is an alkyl group which may contain fluorine atoms having 1 to 7 carbon atoms. Examples of compounds represented by ) are shown below.

[0141] Rf 2 R is a fluorinated alkyl group having 1 to 7 carbon atoms. 7 This is an alkyl group which may contain fluorine atoms having 1 to 7 carbon atoms. The above fluorinated alkyl group is one in which at least one of the hydrogen atoms of the alkyl group is replaced with a fluorine atom. 7 If the alkyl group contains a fluorine atom, it becomes a fluorinated alkyl group. Rf 2 and R 7 In terms of low viscosity, the carbon number is preferably 1 to 7, and more preferably 1 to 2. If the number of carbon atoms becomes too large, the low-temperature properties may deteriorate and the solubility of the electrolyte salt may decrease. Conversely, if the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and an increase in viscosity may occur.

[0142] Examples of fluorinated alkyl groups having one carbon atom include CFH2-, CF2H-, and CF3-. In particular, CFH2- or CF3- are preferred in terms of high-temperature storage characteristics.

[0143] Examples of fluorinated alkyl groups with 2 or more carbon atoms include those with the following general formula (d-1): R d1 -R d2 - (d-1) (In the formula, R d1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom; d2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom; however, R d1 and R d2 A fluorinated alkyl group represented by (at least one of which has a fluorine atom) can be preferably exemplified from the viewpoint of good solubility of the electrolyte salt. Note, R d1 and R d2 It may further contain atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0144] R d1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom. d1 As such, linear or branched alkyl groups having 1 to 6 carbon atoms are preferred. d1 The number of carbon atoms is more preferably 1 to 3.

[0145] R d1 Specifically, as linear or branched alkyl groups, CH3-, CF3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0146] [ka]

[0147] These are some examples.

[0148] Also, R d1If the alkyl group is a linear alkyl group with a fluorine atom, then the names are CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH 2CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2C H2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2 CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2 Examples include CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc.

[0149] Also, R d1 If it is a branched alkyl group having a fluorine atom,

[0150] [ka]

[0151] [ka]

[0152] These are some examples of preferred structures. However, since the presence of CH3- or CF3- branches tends to increase viscosity, it is more preferable that the number of such branches be small (1) or zero.

[0153] R d2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom. d2 The alkylene group may be linear or branched. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below. d2 These are composed of one or a combination of these.

[0154] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0155] (ii) The smallest structural unit of a branched chain:

[0156] [ka]

[0157] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0158] R d2 When the structure is linear, it consists only of the minimum linear structural units described above, with -CH2-, -CH2CH2-, or -CF2- being preferred. -CH2- or -CH2CH2- is more preferred because it can further improve the solubility of the electrolyte salt.

[0159] R d2 If it is branched, it consists of at least one of the branched minimum structural units described above, and the general formula is -(CX a X b )-(X a is H, F, CH3 or CF3;X b is CH3 or CF3. However, X b If it is CF3, X a Examples of materials that can be represented as (where is H or CH3) are preferred. These can particularly further improve the solubility of the electrolyte salt.

[0160] Preferred fluorinated alkyl groups include, specifically, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0161] [ka]

[0162] [ka]

[0163] These are some examples.

[0164] Among them, Rf 2 and R 7 The preferred fluorinated alkyl groups are CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, and CF2H-. CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, and CF2H- are more preferred due to their high flame retardancy, good rate characteristics, and excellent oxidation resistance.

[0165] R 7If it is an alkyl group that does not contain a fluorine atom, it is an alkyl group with 1 to 7 carbon atoms. 7 In terms of low viscosity, the carbon number is preferably 1 to 4, and more preferably 1 to 3.

[0166] Examples of alkyl groups that do not contain fluorine atoms include CH3-, CH3CH2-, (CH3)2CH-, and C3H7-. Among these, CH3- and CH3CH2- are preferred due to their low viscosity and good rate characteristics.

[0167] The above-mentioned fluorinated chain carbonate preferably has a fluorine content of 15 to 70% by mass. When the fluorine content is within the above range, compatibility with solvents and solubility of salts can be maintained. The above-mentioned fluorine content is more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 35% by mass or more, more preferably 60% by mass or less, and even more preferably 50% by mass or less. In this disclosure, the fluorine content is determined based on the structural formula of the above-mentioned fluorinated chain carbonate. {(Number of fluorine atoms × 19) / Molecular weight of fluorinated chain carbonate} × 100 (%) This value was calculated using the method described above.

[0168] The above-mentioned fluorinated chain carbonate is preferably one of the following compounds in terms of its low viscosity.

[0169] [ka]

[0170] As the fluorinated chain carbonate mentioned above, methyl 2,2,2-trifluoroethyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0171] The above-mentioned fluorinated chain carbonates may be used individually, or two or more may be used in any combination and ratio.

[0172] When the above-mentioned fluorinated chain carbonate is included, the content of the above-mentioned fluorinated chain carbonate is preferably 10 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 80% by mass relative to the above-mentioned composition.

[0173] The above-mentioned carboxylic acid ester may be a cyclic carboxylic acid ester or a linear carboxylic acid ester.

[0174] The above-mentioned cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0175] Examples of the above-mentioned non-fluorinated cyclic carboxylic acid esters include non-fluorinated saturated cyclic carboxylic acid esters, and non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group with 2 to 4 carbon atoms are preferred.

[0176] Specific examples of non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group with 2 to 4 carbon atoms include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-valerolactone, and α-methyl-γ-butyrolactone. Among these, γ-butyrolactone and δ-valerolactone are particularly preferred in terms of improving the degree of lithium ion dissociation and load characteristics.

[0177] The above-mentioned non-fluorinated saturated cyclic carboxylic acid esters may be used individually or in combination of two or more in any combination and ratio.

[0178] If the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is included, the content of the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90% by mass, more preferably 0.001 to 90% by mass, even more preferably 1 to 60% by mass, and particularly preferably 5 to 40% by mass relative to the above-mentioned composition.

[0179] The above-mentioned linear carboxylic acid ester may be a non-fluorinated linear carboxylic acid ester or a fluorinated linear carboxylic acid ester. When the above-mentioned solvent contains the above-mentioned linear carboxylic acid ester, the increase in resistance after high-temperature storage of the electrolyte can be further suppressed.

[0180] Examples of the above non-fluorinated linear carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, tert-butyl propionate, tert-butyl butyrate, sec-butyl propionate, sec-butyl butyrate, n-butyl butyrate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl Examples include propyl acetate, n-butyl formate, n-butyl pivalate, n-octyl pivalate, ethyl 2-(dimethoxyphosphoryl) acetate, ethyl 2-(dimethylphosphoryl) acetate, ethyl 2-(diethoxyphosphoryl) acetate, ethyl 2-(diethylphosphoryl) acetate, isopropyl propionate, isopropyl acetate, ethyl formate, ethyl 2-propynyl oxalate, isopropyl formate, isopropyl butyrate, isobutyl formate, isobutyl propionate, isobutyl butyrate, and isobutyl acetate.

[0181] Among these, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0182] The above-mentioned non-fluorinated linear carboxylic acid esters may be used individually or in combination of two or more in any combination and ratio.

[0183] If the above-mentioned non-fluorinated linear carboxylic acid ester is included, the content of the above-mentioned non-fluorinated linear carboxylic acid ester is preferably 0 to 90% by mass, more preferably 0.001 to 90% by mass, even more preferably 1 to 60% by mass, and particularly preferably 5 to 40% by mass relative to the above-mentioned composition.

[0184] The above-mentioned fluorinated linear carboxylic acid ester is a linear carboxylic acid ester having a fluorine atom. Solvents containing the fluorinated linear carboxylic acid ester can be suitably used even under high voltage.

[0185] The above fluorinated chain carboxylic acid esters are based on the following general formula: R 31 COOR 32 (In the formula, R 31 and R 32 These are alkyl groups that may contain fluorine atoms having 1 to 4 carbon atoms, and R 31 and R 32 At least one of them contains a fluorine atom. Fluorinated chain carboxylic acid esters represented by () are preferred because they have good compatibility with other solvents and oxidation resistance.

[0186] R 31 and R 32Examples include non-fluorinated alkyl groups such as methyl group (-CH3), ethyl group (-CH2CH3), propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), n-butyl group (-CH2CH2CH2CH3), and tert-butyl group (-C(CH3)3); -CF3, -CF2H, -CFH2, -CF2CF3, -CF2CF2H, -CF2CFH2, -CH2CF3, -CH2CF2H, -CH2CFH2, -CF2CF2CF3, -CF2CF2CF2H, -CF2CF2CFH2, -CH2CF2CF3, -CH2CF 2CF2H, -CH2CF2CFH2, -CH2CH2CF3, -CH2CH2CF2H, -CH2CH2CFH2, -CF(CF3)2, -CF(CF2H)2, -CF(CFH2)2, -CH(CF3)2, -CH(CF2H)2, -CH(CFH2)2, -CF(OCH) 3)CF3, -CF2CF2CF2CF3, -CF2CF2CF2CF2H, -CF2CF2CF2CFH2, -CH2CF2CF2CF3, -CH2CF2CF2CF2H, -CH2CF2CF2CFH2, -CH2CH2CF2CF3, -CH2CH2CF2CF2H, -C H2CH2CF2CFH2, -CH2CH2CH2CF3, -CH2CH2CH2CF2H, -CH2CH2CH2CFH2, -CF(CF3)CF2CF3, -CF(CF2H)CF2CF3, -CF(CFH2)CF2CF3, -CF(CF3)CF2CF2H, -CF( CF3)CF2CFH2, -CF(CF3)CH2CF3, -CF(CF3)CH2CF2H, -CF(CF3)CH2CFH2, -CH(CF3)CF2CF3, -CH(CF2H)CF2CF3, -CH(CFH2)CF2CF3, -CH(CF3)CF2CF2H, -CH (CF3)CF2CFH2, -CH(CF3)CH2CF3, -CH(CF3)CH2CF2H, -CH(CF3)CH2CFH2, -CF2CF(CF3)CF3, -CF2CF(CF2H)CF3, -CF2CF(CFH2)CF3, -CF2CF(CF3)CF2H, - CF2CF(CF3)CFH2, -CH2CF(CF3)CF3, -CH2CF(CF2H)CF3, -CH2CF(CFH2)CF3, -CH2CF(CF3)CF2H, -CH2CF(CF3)CFH2, -CH2CH(CF3)CF3, -CH2CH(CF2H)CF3,Examples include fluorinated alkyl groups such as -CH2CH(CFH2)CF3, -CH2CH(CF3)CF2H, -CH2CH(CF3)CFH2, -CF2CH(CF3)CF3, -CF2CH(CF2H)CF3, -CF2CH(CFH2)CF3, -CF2CH(CF3)CF2H, -CF2CH(CF3)CFH2, -C(CF3)3, -C(CF2H)3, and -C(CFH2)3. Among these, methyl groups, ethyl groups, -CF3, -CF2H, -CF2CF3, -CH2CF3, -CH2CF2H, -CH2CFH2, -CH2CH2CF3, -CH2CF2CF3, -CH2CF2CF3, -CH2CF2CF2H, and -CH2CF2CFH2 are particularly preferred due to their good compatibility with other solvents, viscosity, and oxidation resistance.

[0187] Specific examples of the above-mentioned fluorinated chain carboxylic acid esters include, for example, CF3CH2C(=O)OCH3 (methyl 3,3,3-trifluoropropionate), HCF2C(=O)OCH3 (methyl difluoroacetate), HCF2C(=O)OC2H5 (ethyl difluoroacetate), CF3C(=O)OCH2CH2CF3, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H (2,2,3,3-tetrafluoropropyl trifluoroacetate), CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tert-butyl trifluoroacetate, and n-butyl trifluoroacetate. Examples include one or more of the following: methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3 (2,2,2-trifluoroethyl acetate), 1H,1H-heptafluorobutyl acetate, methyl 4,4,4-trifluorobutyrate, 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropionate 3,3,3-trifluoropropyl, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, 2,2-difluorobutyl acetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate. Among them, CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H, CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tert-butyl trifluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3, 1H,1H-heptafluorobutyl acetate, 4,4,4-methyl trifluorobutyrate, Ethyl 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropyl 3,3,3-trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate are preferred due to their good compatibility with other solvents and rate characteristics, CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are more preferred, and HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are particularly preferred.

[0188] The above-mentioned fluorinated chain carboxylic acid esters may be used individually, or two or more may be used in any combination and ratio.

[0189] If the above-mentioned fluorinated linear carboxylic acid ester is included, the content of the above-mentioned fluorinated linear carboxylic acid ester is preferably 10 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 80% by mass relative to the above-mentioned composition.

[0190] The solvent preferably contains at least one selected from the group consisting of the cyclic carbonate, the linear carbonate, and the linear carboxylic acid ester, and more preferably contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester. The cyclic carbonate is preferably a saturated cyclic carbonate. A composition containing a solvent with the above composition can further suppress gas generation during high-temperature storage of electrochemical devices.

[0191] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester, it is preferable that the total amount of the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester be 10 to 100% by mass, more preferably 30 to 100% by mass, and even more preferably 50 to 100% by mass relative to the composition.

[0192] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester, the mass ratio of the cyclic carbonate to at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or higher, even more preferably 15 / 85 or higher, particularly preferably 20 / 80 or higher, more preferably 90 / 10 or lower, even more preferably 60 / 40 or lower, and particularly preferably 50 / 50 or lower.

[0193] The solvent may also preferably contain at least one selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated linear carbonate, and the non-fluorinated linear carboxylic acid ester, and more preferably contain the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester. An electrolyte containing a solvent of the above composition can be suitably used in electrochemical devices that operate at relatively low voltages.

[0194] When the solvent contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester, it is preferable that the total amount of the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester be 5 to 100% by mass, more preferably 20 to 100% by mass, and even more preferably 30 to 100% by mass, relative to the composition.

[0195] When the solvent contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester, the mass ratio of the non-fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, even more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0196] The solvent may also preferably contain at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated linear carbonate, and the fluorinated linear carboxylic acid ester, and more preferably contain the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester. An electrolyte containing a solvent of the above composition can be suitably used not only in electrochemical devices used at relatively low voltages, but also in electrochemical devices used at relatively high voltages.

[0197] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester, it is preferable that the total amount of the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester be 10 to 100% by mass, more preferably 30 to 100% by mass, and even more preferably 50 to 100% by mass, relative to the composition.

[0198] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester, the mass ratio of the fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, even more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0199] Furthermore, ionic liquids can also be used as the solvent. An "ionic liquid" is a liquid composed of ions, which are a combination of organic cations and anions.

[0200] The organic cation is not particularly limited, but examples include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0201] The anions that act as counters to these organic cations are not particularly limited, but examples include PF6 anion, PF3(C2F5)3 anion, PF3(CF3)3 anion, BF4 anion, BF2(CF3)2 anion, BF3(CF3) anion, bisoxalatoborate anion, P(C2O4)F2 anion, Tf(trifluoromethanesulfonyl) anion, Nf(nonafluorobutanesulfonyl) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanoamine anion, and halide anions.

[0202] The solvent is preferably a non-aqueous solvent, and the composition of this disclosure is preferably a composition for a non-aqueous electrolyte. The solvent content is preferably 70 to 99.999% by mass in the electrolyte, more preferably 80% by mass or more, and even more preferably 92% by mass or less.

[0203] The compositions of this disclosure preferably further contain an electrolyte salt. As the electrolyte salt, any salt that can be used as an electrolyte can be used, such as lithium salts, ammonium salts, metal salts, liquid salts (ionic liquids), inorganic polymer type salts, organic polymer type salts, etc.

[0204] Lithium salts are preferred as the electrolyte salts for the electrolyte solution of lithium-ion secondary batteries. Any lithium salt can be used as described above, specifically including the following: For example, LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, LiWF7, LiAsF6, LiAlCl4, LiI, LiBr, LiCl, LiB 10 Cl 10 Inorganic lithium salts such as Li2SiF6, Li2PFO3, and LiPO2F2; Lithium tungstate compounds such as LiWOF5; Lithium carboxylate salts such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li, and CF3CF2CF2CF2CO2Li; Lithium salts containing an S=O group, such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li, lithium methyl sulfate, lithium ethyl sulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethyl sulfate; Lithium imide salts such as LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), iN(CF3SO2)2, LiN(C2F5SO2)2, lithium bisperfluoroethanesulfonylimide, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, lithium cyclic 1,2-ethanedisulfonylimide, lithium cyclic 1,3-propanedisulfonylimide, lithium cyclic 1,4-perfluorobutanedisulfonylimide, LiN(CF3SO2)(FSO2), LiN(CF3SO2)(C3F7SO2), LiN(CF3SO2)(C4F9SO2), LiN(POF2)2, etc. Lithium methide salts such as LiC(FSO2)3, LiC(CF3SO2)3, and LiC(C2F5SO2)3; Other formulas: LiPF a (C n F 2n+1 )6-a Salts represented by (wherein the formula a is an integer from 0 to 5 and n is an integer from 1 to 6) (e.g., LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), LiPF4(CF3)2, LiPF4(C2F5)2), LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2, etc., fluorine-containing organolithium salts, LiSCN, LiB(CN)4, LiB(C6H5)4, Li2(C2O4), LiP(C2O4)3, Li2B 12 F b H 12-b Examples include (where b is an integer between 0 and 3).

[0205] Among them, LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO2F2, FSO3Li, CF3SO3Li, iN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, Li PF3(C2F5)3 and the like are preferred because they have the effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, and cycle characteristics, at least one lithium salt selected from the group consisting of LiPF6, LiN(FSO2)2 (lithium bis(fluorosulfonyl)imide (LIFSI)), and LiN(CF3SO2)2 (lithium bis(trifluoromethanesulfonyl)imide (LITFSI)) is more preferred, and at least one lithium salt selected from the group consisting of LiPF6, LiFSI, and LiTFSI is particularly preferred.

[0206] These electrolyte salts may be used individually or in combination of two or more. Preferred examples of combinations of two or more include the use of LiPF6 and LiBF4, or LiPF6 with LiPO2F2, C2H5OSO3Li, or FSO3Li, which have the effect of improving high-temperature storage characteristics, load characteristics, and cycle characteristics.

[0207] In this case, there are no restrictions on the amount of LiBF4, LiPO2F2, C2H5OSO3Li, or FSO3Li blended relative to 100% by mass of the total electrolyte. It is arbitrary as long as it does not significantly impair the effects of this disclosure. However, the amount is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the electrolyte.

[0208] Another example is the combined use of inorganic lithium salts and organic lithium salts, which have the effect of suppressing degradation due to high-temperature storage. Preferred organic lithium salts include CF3SO3Li, LiN(FSO2)2(LIFSI), LiN(FSO2)(CF3SO2), LiN(CF3SO2)2(LITFSI), LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, etc. In this case, the proportion of the organic lithium salt to 100% by mass of the total electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and also preferably 30% by mass or less, particularly preferably 20% by mass or less.

[0209] The concentrations of these electrolyte salts in the electrolyte are not particularly limited as long as they do not impair the effects of the present disclosure. In order to maintain a good electrical conductivity of the electrolyte and ensure good battery performance, the total molar concentration of lithium in the electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, even more preferably 0.5 mol / L or more, particularly preferably 1.0 mol / L or more, and also preferably 3 mol / L or less, more preferably 2.5 mol / L or less, and even more preferably 2.0 mol / L or less.

[0210] If the total molar concentration of lithium is too low, the electrical conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to increased viscosity, which may reduce battery performance.

[0211] For the electrolyte solution used in electric double-layer capacitors, ammonium salts are preferred. Examples of the above ammonium salts include (IIa) to (IIe). (IIa) Tetraalkyl quaternary ammonium salt General formula (IIa):

[0212] [ka] (In the formula, R 1a , R 2a , R 3a and R 4a The alkyl groups are the same or different, and may each contain an ether bond between 1 and 6 carbon atoms; X - (is anion) Tetraalkyl quaternary ammonium salts represented by can be preferably exemplified. Furthermore, those in which some or all of the hydrogen atoms of the ammonium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improved oxidation resistance.

[0213] For example, consider the general formula (IIa-1):

[0214] [ka] (In the formula, R 1a , R 2a and X - (The same as above; x and y are the same or different integers from 0 to 4, and x + y = 4) Tetraalkylquaternary ammonium salts represented by the formula (IIa-2):

[0215] [ka] (In the formula, R 5a R is an alkyl group having 1 to 6 carbon atoms; 6a R is a divalent hydrocarbon group having 1 to 6 carbon atoms; 7a is an alkyl group having 1 to 4 carbon atoms; z is 1 or 2; X - (is anion) Alkyl ether group-containing trialkylammonium salts represented by Examples include the introduction of alkyl ether groups, which can reduce viscosity.

[0216] Anion X - This can be either an inorganic or organic anion. An example of an inorganic anion is AlCl4. - BF4 - PF6 - AsF6 - TaF6 - , I - SbF6 - Examples of organic anions include bisoxalatoborate anion, difluorooxalatoborate anion, tetrafluorooxalatophosphate anion, difluorobisoxalatophosphate anion, and CF3COO - CF3SO3 - (CF3SO2)2N - , (C2F5SO2)2N - These are some examples.

[0217] Of these, BF4 was chosen due to its good oxidation resistance and ionic dissociation properties. -PF6 - AsF6 - SbF6 - It is preferable.

[0218] Suitable examples of tetraalkyl quaternary ammonium salts include Et4NBF4, Et4NClO4, Et4NPF6, Et4NAsF6, Et4NSbF6, Et4NCF3SO3, Et4N(CF3SO2)2N, Et4NC4F9SO3, Et3MeNBF4, Et3MeNClO4, Et3MeNPF6, Et3MeNAsF6, Et3MeNSbF6, Et3MeNCF3SO3, Et3MeN(CF3SO2)2N, and Et3MeNC4F9SO3. In particular, examples include Et4NBF4, Et4NPF6, Et4NSbF6, Et4NAsF6, Et3MeNBF4, and N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium salt.

[0219] (IIb) Spiro ring bipyrrolidinium salt General formula (IIb-1):

[0220] [ka] (In the formula, R 8a and R 9a The same or different alkyl groups, both having 1 to 4 carbon atoms; X - (where n1 is an anion; n1 is an integer between 0 and 5; n2 is an integer between 0 and 5) Spiro ring bipyrrolidinium salts represented by the general formula (IIb-2):

[0221] [ka] (In the formula, R 10a and R 11a The same or different alkyl groups, both having 1 to 4 carbon atoms; X - (where n3 is an anion; n4 is an integer between 0 and 5; n4 is an integer between 0 and 5) Spiro ring bipyrrolidinium salts represented by, or general formula (IIb-3):

[0222] [ka] (In the formula, R 12a and R 13a The same or different alkyl groups, both having 1 to 4 carbon atoms; X - (where n5 is an anion; n6 is an integer between 0 and 5; n5 is an integer between 0 and 5) A spiro ring bipyrrolidinium salt represented by [formula] is preferred. Furthermore, a spiro ring bipyrrolidinium salt in which some or all of the hydrogen atoms are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms is also preferred because it improves oxidation resistance.

[0223] Anion X - Preferred specific examples are the same as in case (IIa). Among these, BF4-, PF6-, (CF3SO2)2N-, or (C2F5SO2)2N- are preferred due to their high dissociability and low internal resistance under high voltage.

[0224] Preferred specific examples of spiro ring bipyrrolidinium salts include, for example, [ka] These are some examples.

[0225] This spiro ring bipyrrolidinium salt exhibits excellent solubility in solvents, oxidation resistance, and ionic conductivity.

[0226] (IIc) Imidazolium salt General formula (IIc):

[0227] [ka] (In the formula, R 14a and R 15a The same or different alkyl groups, both having 1 to 6 carbon atoms; X - (is anion) The imidazolium salts shown are preferred examples. Furthermore, those imidazolium salts in which some or all of the hydrogen atoms are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred because they have improved oxidation resistance.

[0228] Anion X - A preferred example of this is the same as in (IIa).

[0229] A good example would be, for instance,

[0230] [ka] These are some examples.

[0231] This imidazolium salt is excellent in that it has low viscosity and good solubility.

[0232] (IId): N-alkylpyridinium salt General formula (IId):

[0233] [ka] (In the formula, R 16a X is an alkyl group having 1 to 6 carbon atoms; - (is anion) A preferred example is an N-alkylpyridinium salt represented by . Furthermore, a salt in which some or all of the hydrogen atoms of the N-alkylpyridinium salt are substituted with a fluorine atom and / or a fluorine-containing alkyl group having 1 to 4 carbon atoms is also preferred because it improves oxidation resistance.

[0234] Anion X - A preferred example of this is the same as in (IIa).

[0235] A good example would be, for instance,

[0236] [ka] These are some examples.

[0237] This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

[0238] (IIe)N,N-dialkylpyrrolidinium salt General formula (IIe):

[0239] [ka] (In the formula, R 17a and R 18a The same or different alkyl groups, both having 1 to 6 carbon atoms; X - (is anion) A preferred example is the N,N-dialkylpyrrolidinium salt represented by . Furthermore, a salt in which some or all of the hydrogen atoms of the N,N-dialkylpyrrolidinium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms is also preferred because it improves oxidation resistance.

[0240] Anion X - A preferred example of this is the same as in (IIa).

[0241] A good example would be, for instance,

[0242] [ka]

[0243] [ka] These are some examples.

[0244] This N,N-dialkylpyrrolidinium salt is excellent in that it has low viscosity and good solubility.

[0245] Of these ammonium salts, (IIa), (IIb), and (IIc) are preferred in terms of good solubility, oxidation resistance, and ionic conductivity, and furthermore,

[0246] [ka] (In the formula, Me is a methyl group; Et is an ethyl group; X - (x and y are the same as in equation (IIa-1)) It is preferable.

[0247] Furthermore, lithium salts may be used as the electrolyte salt for electric double-layer capacitors. Preferred lithium salts include, for example, LiPF6, LiBF4, LiN(FSO2)2, LiAsF6, LiSbF6, and LiN(SO2C2H5)2. To further improve capacity, magnesium salts may be used. Preferred magnesium salts include, for example, Mg(ClO4)2 and Mg(OOC2H5)2.

[0248] When the electrolyte salt is the above-mentioned ammonium salt, the concentration is preferably 0.7 mol / liter or higher. If it is less than 0.7 mol / liter, not only will the low-temperature characteristics deteriorate, but the initial internal resistance may also increase. The concentration of the above-mentioned electrolyte salt is more preferably 0.9 mol / liter or higher. The upper limit of the above concentration is preferably 2.0 mol / liter or less, and more preferably 1.5 mol / liter or less, in terms of low-temperature characteristics. When the above ammonium salt is triethylmethylammonium tetrafluoroborate (TEMABF4), its concentration is preferably 0.7 to 1.5 moles / liter, in terms of excellent low-temperature characteristics. Furthermore, in the case of spirobipyrrolidinium tetrafluoroborate (SBPBF4), a concentration of 0.7 to 2.0 moles / liter is preferable.

[0249] The compositions disclosed herein are of general formula (2): [ka] (In the formula, X 21 is a base containing at least H or C, n21 is an integer from 1 to 3, Y 21 and Z 21 The group is the same or different and contains at least H, C, O or F, n22 is 0 or 1, Y 21 and Z 21 The compounds may bond to each other to form a ring. Preferably, the electrolyte further contains compound (2) represented by ). When the electrolyte contains compound (2), the volume retention rate is less likely to decrease and the amount of gas generated is less likely to increase, even when stored at high temperatures.

[0250] If n21 is 2 or 3, then 2 or 3 X 21 They may be the same or different. Y 21 and Z 21 If there are multiple instances of Y, then there are multiple instances of Y. 21 and Z 21 They may be the same or different.

[0251] X 21 For example, -CY 21 Z 21 -(In the formula, Y 21 and Z 21 (As stated above) or -CY 21 =CZ 21 -(In the formula, Y 21 and Z 21 The group shown above is preferred.

[0252] Y 21 Preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is used. Z 21 Preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is used.

[0253] Or, Y 21 and Z 21 These atoms can bond with each other to form a carbocyclic or heterocyclic ring, which may contain unsaturated bonds and may be aromatic. The number of carbon atoms in the ring is preferably 3 to 20.

[0254] Next, specific examples of compound (2) will be described. In the following examples, "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure, to the extent that it does not contradict the spirit of this disclosure. Examples include dimers, trimers, and tetramers consisting of multiple acid anhydrides, or isostructural isomers having branched chains but the same number of carbon atoms in the substituents, or those in which the substituents are attached to the acid anhydride at different sites.

[0255] Specific examples of acid anhydrides that form a five-membered ring structure include succinic anhydride, methylsuccinate anhydride (4-methylsuccinate anhydride), dimethylsuccinate anhydride (4,4-dimethylsuccinate anhydride, 4,5-dimethylsuccinate anhydride, etc.), 4,4,5-trimethylsuccinate anhydride, 4,4,5,5-tetramethylsuccinate anhydride, 4-vinylsuccinate anhydride, 4,5-divinylsuccinate anhydride, phenylsuccinate anhydride (4-phenylsuccinate anhydride), and 4,5-diphenylsuccinate anhydride. Examples include aqueous solutions, 4,4-diphenylsuccinic anhydride, citraconic anhydride, maleic anhydride, methylmaleic anhydride (4-methylmaleic anhydride), 4,5-dimethylmaleic anhydride, phenylmaleic anhydride (4-phenylmaleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, and their analogues.

[0256] Specific examples of acid anhydrides forming a six-membered ring structure include cyclohexanedicarboxylic acid anhydride (such as cyclohexane-1,2-dicarboxylic acid anhydride), 4-cyclohexene-1,2-dicarboxylic acid anhydride, glutaric acid anhydride, glutaconic acid anhydride, 2-phenylglutaric acid anhydride, and their analogues.

[0257] Other specific examples of acid anhydrides that form a cyclic structure include 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic acid anhydride, diglycolic acid anhydride, and their analogues.

[0258] Specific examples of acid anhydrides that form a cyclic structure and are substituted with halogen atoms include monofluorosuccinic anhydride (such as 4-fluorosuccinic anhydride), 4,4-difluorosuccinic anhydride, 4,5-difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride (4,4,5,5-tetrafluorosuccinic anhydride), 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, trifluoromethylmaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and their analogues.

[0259] Among the compounds (2), glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, maleic anhydride, methylmaleic anhydride, trifluoromethyl Maleic anhydride, phenylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, tetrafluorosuccinic anhydride, etc. are preferred, maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride are more preferred, and maleic anhydride and succinic anhydride are even more preferred.

[0260] Compound (2) has the general formula (3):

[0261] [ka] (In the formula, X 31 ~X 34 (3) is a compound represented by the same or different group (containing at least H, C, O, or F), and the general formula (4):

[0262] [ka] (In the formula, X 41 and X 42 Preferably, is at least one selected from the group consisting of compounds (4) that are the same or different and represent a group containing at least H, C, O, or F.

[0263] X 31 ~X 34Preferably, it is the same or different, and selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups. 31 ~X 34 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0264] X 31 ~X 34 More preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is the same or different.

[0265] X 41 and X 42 Preferably, it is the same or different, and selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups. 41 and X 42 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0266] X 41 and X 42 More preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is the same or different.

[0267] Compound (3) is preferably one of the following compounds.

[0268] [ka]

[0269] Compound (4) is preferably one of the following compounds.

[0270] [ka]

[0271] The above composition is preferable to contain 0.0001 to 15% by mass of compound (2) relative to the electrolyte, as it does not easily decrease in volume retention or increase in gas generation even when stored at high temperatures. The content of compound (2) is more preferably 0.01 to 10% by mass, even more preferably 0.1 to 3% by mass, and particularly preferably 0.1 to 1.0% by mass.

[0272] When the above composition contains both compounds (3) and (4), the volume retention rate does not decrease easily and the amount of gas generated does not increase easily even when stored at high temperatures. Therefore, the above electrolyte preferably contains 0.08 to 2.50% by mass of compound (3) and 0.02 to 1.50% by mass of compound (4) relative to the above electrolyte, and more preferably contains 0.80 to 2.50% by mass of compound (3) and 0.08 to 1.50% by mass of compound (4).

[0273] The compositions of this disclosure may include at least one selected from the group consisting of nitrile compounds represented by the following general formulas (1a), (1b), and (1c). [ka] (In the formula, R a and R b Each of these independently represents a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms are replaced with halogen atoms. n represents an integer from 1 to 10. [ka] (In the formula, R c This includes hydrogen atoms, halogen atoms, alkyl groups, groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 X is an alkylene group. c1 represents an oxygen atom or a sulfur atom. ) represents a group represented by ). dand R e Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. (m represents an integer from 1 to 10.) [ka] (In the formula, R f , R g , R h and R i Each of these independently represents a group containing a cyano group (CN), a hydrogen atom (H), a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms are replaced with halogen atoms. However, R f , R g , R h and R i At least one of these groups contains a cyano group. (l represents an integer from 1 to 3.) This improves the high-temperature storage characteristics of electrochemical devices. The above nitrile compounds may be used alone, or two or more may be used in any combination and ratio.

[0274] In the above general formula (1a), R a and R b Each of these is independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Among these, fluorine is preferred. Alkyl groups with 1 to 5 carbon atoms are preferred. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl groups. Examples of groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms include the aforementioned groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. R a and R bIf is an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, then R a and R b These elements may be bonded to each other to form a ring structure (for example, a cyclohexane ring). R a and R b It is preferable that this is a hydrogen atom or an alkyl group.

[0275] In the general formula (1a) above, n is an integer from 1 to 10. If n is 2 or greater, there are n R a They may all be the same, or at least some of them may be different. b The same applies to n. n is preferably an integer between 1 and 7, and more preferably an integer between 2 and 5.

[0276] Dinitrile and tricarbonitrile are preferred as nitrile compounds represented by the above general formula (1a). Specific examples of dinitriles include malononitrile, succinonitrile, glutalonitrile, adiponitrile, pimelonitrile, suberonitrile, azeranitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2 ,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2,2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3- Dimethyl succinonitrile, 2,2-diisobutyl-3,3-dimethyl succinonitrile, 2-methyl glutaronitrile, 2,3-dimethyl glutaronitrile, 2,4-dimethyl glutaronitrile, 2,2,3,3-tetramethyl glutaronitrile, 2,2,4,4-tetramethyl glutaronitrile, 2,2,3,4-tetramethyl glutaronitrile, 2,3,3,4-tetramethyl glutaronitrile, 1,4-dicyanopentane, 2,6-disy Examples include anoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedithio)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, butanenitrile, phthalonitrile, etc. Of these, succinonitrile, glutalonitrile, and adiponitrile are particularly preferred. Furthermore, specific examples of tricarbonitrine include pentanetricarbonitrine, propanetricarbonitrine, 1,3,5-hexanetricarbonitrine, 1,3,6-hexanetricarbonitrine, heptanetricarbonitrine, 1,2,3-propanetricarbonitrine, 1,3,5-pentanetricarbonitrine, cyclohexanetricarbonitrine, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, tris(2-cyanoethyl)amine, etc., with 1,3,6-hexanetricarbonitrine and cyclohexanetricarbonitrine being particularly preferred, and cyclohexanetricarbonitrine being the most preferred.

[0277] In the above general formula (1b), R c This includes hydrogen atoms, halogen atoms, alkyl groups, groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 X is an alkylene group. c1 represents an oxygen atom or a sulfur atom. ) is a group represented by R d and R e Each of these is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms, alkyl groups, and groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms are those shown for the general formula (1a) above. The above NC-R c1 -X c1 -R in c1 This is an alkylene group. A preferred alkylene group has 1 to 3 carbon atoms. R c , R d and R e Preferably, each of these is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. R c , R d and R ePreferably, at least one of the groups is a halogen atom or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom, and more preferably, a fluorine atom or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a fluorine atom. R d and R e If is an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, then R d and R e These elements may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0278] In the general formula (1b) above, m is an integer from 1 to 10. If m is 2 or greater, there are m R d They may all be the same, or at least some of them may be different. e The same applies to m. m is preferably an integer between 2 and 7, and more preferably an integer between 2 and 5.

[0279] Examples of nitrile compounds represented by the above general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile, benzonitrile, and the like. Of these, 3,3,3-trifluoropropionitrile is particularly preferred.

[0280] In the above general formula (1c), Rf , R g , R h and R i Each of these is independently a group containing a cyano group (CN), a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms, alkyl groups, and groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms are those shown for the general formula (1a) above. Groups containing a cyano group include not only cyano groups but also groups in which at least some of the hydrogen atoms of an alkyl group are replaced with cyano groups. Examples of alkyl groups in this case are those exemplified for general formula (1a) above. R f , R g , R h and R i At least one of these groups is a cyano group. Preferably, R f , R g , R h and R i At least two of these groups contain a cyano group, and more preferably, R h and R i The group must contain a cyano group. h and R i If R is a group containing a cyano group, f and R g It is preferable that it be a hydrogen atom.

[0281] In the general formula (1c) above, l is an integer from 1 to 3. If l is 2 or greater, there are l R f They may all be the same, or at least some of them may be different. g The same applies to . l is preferably an integer between 1 and 2.

[0282] Examples of nitrile compounds represented by the above general formula (1c) include 3-hexendinitrile, mucononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentennitrile, 2-methyl-2-pentennitrile, 3-methyl-2-pentennitrile, and 2-hexennitrile, with 3-hexendinitrile and mucononitrile being preferred, and 3-hexendinitrile being particularly preferred.

[0283] The content of the above nitrile compound is preferably 0.2 to 7% by mass relative to the electrolyte. This further improves the high-temperature storage characteristics and safety of the electrochemical device at high voltage. The lower limit of the total content of the above nitrile compound is more preferably 0.3% by mass, and even more preferably 0.5% by mass. The upper limit is more preferably 5% by mass, even more preferably 2% by mass, and particularly preferably 0.5% by mass.

[0284] The compositions of this disclosure may contain compounds having an isocyanate group (hereinafter sometimes abbreviated as "isocyanate"). The isocyanate is not particularly limited, and any isocyanate can be used. Examples of isocyanates include monoisocyanates, diisocyanates, triisocyanates, and the like.

[0285] Specific examples of monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxycarbonyl isocyanate, ethoxycarbonyl isocyanate, propoxycarbonyl isocyanate, butoxycarbonyl isocyanate, methoxysulfonyl isocyanate, ethoxysulfonyl isocyanate, propoxysulfonyl isocyanate, butoxysulfonyl isocyanate, fluorosulfonyl isocyanate, methyl isocyanate, butyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and ethyl isocyanate.

[0286] Specific examples of diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanathoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, and 1,4-diisocyanato-2,3-difluorobutane. 1,5-Diisocyanato-2-pentene, 1,5-Diisocyanato-2-methylpentane, 1,6-Diisocyanato-2-hexene, 1,6-Diisocyanato-3-hexene, 1,6-Diisocyanato-3-fluorohexane, 1,6-Diisocyanato-3,4-Difluorohexane, Toluene diisocyanate, Xylene diisocyanate, Tolylene diisocyanate, 1,2-Bis(isocyanatomethyl)cyclohexane, 1,3-Bis(isocyanatomethyl) (Cyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate Examples include bicyclo[2.2.1]heptane-2,5-diirbis(methyl isocyanate), bicyclo[2.2.1]heptane-2,6-diirbis(methyl isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylenediisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, etc.

[0287] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylenediisocyanate, 1,3,5-triisocyanatemethylbenzene, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 4-(isocyanatomethyl)octamethylene=diisocyanate.

[0288] Among these, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate are preferred because they are readily available industrially, keep the manufacturing cost of the electrolyte low, and contribute to the formation of a stable film-like structure from a technical standpoint, making them more preferable to use.

[0289] The isocyanate content is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is preferably 0.001% by mass or more and 1.0% by mass or less relative to the composition. If the isocyanate content is above this lower limit, a sufficient improvement in cycle characteristics can be brought about in non-aqueous electrolyte secondary batteries. If it is below this upper limit, an initial increase in resistance of non-aqueous electrolyte secondary batteries can be avoided. The isocyanate content is more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and more preferably 0.8% by mass or less, even more preferably 0.7% by mass or less, and particularly preferably 0.6% by mass or less.

[0290] The compositions of this disclosure may contain cyclic sulfonic acid esters. The cyclic sulfonic acid esters are not particularly limited, and any cyclic sulfonic acid esters can be used. Examples of cyclic sulfonic acid esters include saturated cyclic sulfonic acid esters, unsaturated cyclic sulfonic acid esters, saturated cyclic disulfonic acid esters, and unsaturated cyclic disulfonic acid esters.

[0291] Specific examples of saturated cyclic sulfonic acid esters include 1,3-propanesultone, 1-fluoro-1,3-propanesultone, 2-fluoro-1,3-propanesultone, 3-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 2-methyl-1,3-propanesultone, 3-methyl-1,3-propanesultone, 1,3-butanesultone, 1,4-butanesultone, 1-fluoro-1,4-butanesultone, 2-fluoro-1,4-butanesultone, 3-fluoro-1,4-butanesultone, 4-fluoro-1,4-butanesultone, 1-methyl-1,4-butanesultone, 2-methyl-1,4-butanesultone, 3-methyl-1,4-butanesultone, 4-methyl-1,4-butanesultone, and 2,4-butanesultone.

[0292] Specific examples of unsaturated cyclic sulfonic acid esters include 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2-fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, and 2-methyl-1-propene n-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4 -Sultone, 1-fluoro-2-butene-1,4-sultone, 2-fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1,3-propensultone, 1-fluoro-3-butene-1,4-sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1-butene-1,4-sultone, 2-methyl-1-butene Examples include n-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, and 4-methyl-3-butene-14-sultone.

[0293] Among these, 1,3-propanesultone, 1-fluoro-1,3-propanesultone, 2-fluoro-1,3-propanesultone, 3-fluoro-1,3-propanesultone, and 1-propene-1,3-sultone are more preferably used due to their availability and their ability to contribute to the formation of stable film-like structures. The content of the cyclic sulfonic acid ester is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is preferably 0.001% by mass or more and 3.0% by mass or less relative to the electrolyte.

[0294] If the cyclic sulfonic acid ester content is above this lower limit, a sufficient improvement in cycle characteristics can be achieved in non-aqueous electrolyte secondary batteries. If it is below this upper limit, an increase in the manufacturing cost of non-aqueous electrolyte secondary batteries can be avoided. The cyclic sulfonic acid ester content is more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.8% by mass or less.

[0295] The compositions of this disclosure may further contain polyethylene oxide having a weight-average molecular weight of 2000 to 4000 and having -OH, -OCOOH, or -COOH at the end. By including such compounds, the stability of the electrode interface can be improved, thereby enhancing the properties of the electrochemical device. Examples of the polyethylene oxides mentioned above include polyethylene oxide monool, polyethylene oxide carboxylic acid, polyethylene oxide diol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, and the like. These may be used individually or in combination of two or more. In particular, a mixture of polyethylene oxide monool and polyethylene oxide diol, and a mixture of polyethylene carboxylic acid and polyethylene dicarboxylic acid are preferred, as they result in better characteristics of the electrochemical device.

[0296] If the weight-average molecular weight of the polyethylene oxide is too low, it may be more susceptible to oxidative decomposition. A weight-average molecular weight of 3000 to 4000 is more preferable. The above weight-average molecular weight can be measured by converting it to polystyrene equivalent using gel permeation chromatography (GPC).

[0297] The polyethylene oxide content in the above composition is 1 × 10 -6 ~1 × 10 -2 A concentration of mol / kg is preferable. If the polyethylene oxide content is too high, it may impair the properties of the electrochemical device. The polyethylene oxide content mentioned above is 5 × 10 -6 A concentration of mol / kg or higher is more preferable.

[0298] The compositions of this disclosure may further contain, as additives, fluorinated saturated cyclic carbonates, unsaturated cyclic carbonates, overcharge inhibitors, and other known auxiliary agents. This makes it possible to suppress the deterioration of the properties of electrochemical devices.

[0299] Examples of fluorinated saturated cyclic carbonates include compounds represented by the general formula (A) described above. Among these, fluoroethylene carbonate, difluoroethylene carbonate, monofluoromethylethylene carbonate, trifluoromethylethylene carbonate, and 2,2,3,3,3-pentafluoropropylethylene carbonate (4-(2,2,3,3,3-pentafluoropropyl)-[1,3]dioxolan-2-one) are preferred. Fluorinated saturated cyclic carbonates may be used individually or in combination of two or more in any combination and ratio.

[0300] The content of the above-mentioned fluorinated saturated cyclic carbonate is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass, relative to the above-mentioned composition.

[0301] Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with substituents having aromatic rings or carbon-carbon double or carbon-carbon triple bonds, phenyl carbonates, vinyl carbonates, allyl carbonates, and catechol carbonates.

[0302] Examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, ethynylethylene carbonate, propargylethylene carbonate, methyl vinylene carbonate, and dimethyl vinylene carbonate.

[0303] Specific examples of ethylene carbonates substituted with substituents having aromatic rings or carbon-carbon double or carbon-carbon triple bonds include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, and 4-allyl-5-ethynylethylene. Examples include nylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, and 4-methyl-5-allylethylene carbonate.

[0304] Among these, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, and 4-vinyl-5-ethynylethylene carbonate are preferred as unsaturated cyclic carbonates. Furthermore, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are particularly preferred because they form an even more stable interfacial protective film, with vinylene carbonate being the most preferred.

[0305] The molecular weight of the unsaturated cyclic carbonate is not particularly limited and can be any as long as it does not significantly impair the effects of this disclosure. Preferably, the molecular weight is 50 or more and 250 or less. Within this range, it is easy to ensure the solubility of the unsaturated cyclic carbonate in the electrolyte, and the effects of this disclosure are easily realized. More preferably, the molecular weight of the unsaturated cyclic carbonate is 80 or more, and more preferably 150 or less.

[0306] The method for producing unsaturated cyclic carbonates is not particularly limited, and they can be produced by arbitrarily selecting known methods.

[0307] Unsaturated cyclic carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0308] The content of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure. The content of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more, per 100% by mass of the composition. Furthermore, the content is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. Within the above range, electrochemical devices using the electrolyte are more likely to exhibit a sufficient improvement in cycle characteristics, and it is easier to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity maintenance rate.

[0309] As unsaturated cyclic carbonates, in addition to the non-fluorinated unsaturated cyclic carbonates mentioned above, fluorinated unsaturated cyclic carbonates can also be suitably used. Fluorinated unsaturated cyclic carbonates are cyclic carbonates having unsaturated bonds and fluorine atoms. The number of fluorine atoms in a fluorinated unsaturated cyclic carbonate is not particularly limited, as long as it is one or more. In particular, the number of fluorine atoms is usually six or less, preferably four or less, and one or two atoms is most preferred.

[0310] Examples of fluorinated unsaturated cyclic carbonates include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with substituents having aromatic rings or carbon-carbon double bonds.

[0311] Examples of fluorinated vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, and 4-fluoro-5-vinylvinylene carbonate.

[0312] Examples of fluorinated ethylene carbonate derivatives substituted with substituents having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, and 4,5-difluoro-4- Examples include lylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, and 4,5-difluoro-4-phenylethylene carbonate.

[0313] Among them, fluorinated unsaturated cyclic carbonates include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, and 4,4-difluoro-4-vinylethylene carbonate. Carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate are more preferably used because they form a stable interfacial protective film.

[0314] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and can be any as long as it does not significantly impair the effects of this disclosure. Preferably, the molecular weight is 50 or more and 500 or less. Within this range, it is easy to ensure the solubility of the fluorinated unsaturated cyclic carbonate in the electrolyte.

[0315] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and it can be produced by arbitrarily selecting any known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

[0316] Fluorinated unsaturated cyclic carbonates may be used individually or in any combination and ratio of two or more types. Furthermore, the content of fluorinated unsaturated cyclic carbonates is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure. Typically, the content of fluorinated unsaturated cyclic carbonates is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and also preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, in 100% by mass of the composition. Within this range, electrochemical devices using the electrolyte are more likely to exhibit a sufficient improvement in cycle characteristics, and it is easier to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity maintenance rate.

[0317] The compositions of this disclosure may include compounds having triple bonds. The type of compound is not particularly limited as long as it has one or more triple bonds in its molecule. Specific examples of compounds having a triple bond include the following compounds: Hydrocarbon compounds such as 1-pentine, 2-pentine, 1-hexine, 2-hexine, 3-hexine, 1-heptine, 2-heptine, 3-heptine, 1-octin, 2-octin, 3-octin, 4-octin, 1-nonine, 2-nonine, 3-nonine, 4-nonine, 1-dodecine, 2-dodecine, 3-dodecine, 4-dodecine, 5-dodecine, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butine, 4-phenyl-1-butine, 4-phenyl-1-butine, 1-phenyl-1-pentine, 5-phenyl-1-pentine, 1-phenyl-1-hexine, 6-phenyl-1-hexine, diphenylacetylene, 4-ethynyltoluene, and dicyclohexylacetylene;

[0318] 2-Propynylmethyl carbonate, 2-Propynylethyl carbonate, 2-Propynylpropyl carbonate, 2-Propynylbutyl carbonate, 2-Propynylphenyl carbonate, 2-Propynylcyclohexyl carbonate, Di-2-Propynyl carbonate, 1-Methyl-2-Propynylmethyl carbonate, 1,1-Dimethyl-2-Propynylmethyl carbonate, 2-Butynylmethyl carbonate, 3-Butynylmethyl carbonate, 2-Pentynylmethyl carbonate Monocarbonates such as nates, 3-pentinylmethyl carbonate, and 4-pentinylmethyl carbonate; dicarbonates such as 2-butyn-1,4-diol dimethyl dicarbonate, 2-butyn-1,4-diol diethyl dicarbonate, 2-butyn-1,4-diol dipropyl dicarbonate, 2-butyn-1,4-diol dibutyl dicarbonate, 2-butyn-1,4-diol diphenyl dicarbonate, and 2-butyn-1,4-diol dicyclohexyl dicarbonate;

[0319] 2-propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexylcarboxylic acid, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propynyl propionate, 1,1-dimethyl-2-propynyl butyrate, 1,1-dimethyl-2-propynyl benzoate, 1,1-dimethyl-2-propynyl cyclohexylcarboxylic acid, 2-butynyl acetate, 3-butynyl acetate, 2-pentynyl acetate, 3-pentynyl acetate, 4-pentynyl acetate, methyl acrylate, Ethyl acrylate, propyl acrylate, vinyl acrylate, 2-propenyl acrylate, 2-butenyl acrylate, 3-butenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propenyl methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, methyl 2-propate, ethyl 2-propate, propyl 2-propate, vinyl 2-propate, 2-propenyl 2-propate, 2-butenyl 2-propate, 3-butenyl 2-propate, 2 - Methyl butate, ethyl butate, propyl butate, vinyl butate, 2-propenyl butate, 2-butenyl butate, 3-butenyl butate, methyl butate, ethyl butate, propyl butate, vinyl butate, 2-propenyl butate, 2-butenyl butate, 3-butenyl butate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate Monocarboxylic acid esters such as 3-butenyl pentinate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate, 3-butenyl pentinate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate, 3-butenyl pentinate, fumarate esters, methyl trimethylacetate, ethyl trimethylacetate;

[0320] Dicarboxylic acid esters such as 2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne-1,4-diol dicyclohexanecarboxylate, hexahydrobenzo[1,3,2]dioxathiolan-2-oxide (1,2-cyclohexanediol, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, etc.);

[0321] Oxalate diesters such as methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, propyl 2-propynyl oxalate, 2-propynyl vinyl oxalate, allyl 2-propynyl oxalate, di-2-propynyl oxalate, 2-butynylmethyl oxalate, 2-butynylethyl oxalate, 2-butynylpropyl oxalate, 2-butynyl vinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynylmethyl oxalate, 3-butynylethyl oxalate, 3-butynylpropyl oxalate, 3-butynyl vinyl oxalate, allyl 3-butynyl oxalate, and di-3-butynyl oxalate;

[0322] Phosphine oxides such as methyl(2-propynyl)(vinyl)phosphine oxide, divinyl(2-propynyl)phosphine oxide, di(2-propynyl)(vinyl)phosphine oxide, di(2-propenyl)2(-propynyl)phosphine oxide, di(2-propynyl)(2-propenyl)phosphine oxide, di(3-butenyl)(2-propynyl)phosphine oxide, and di(2-propynyl)(3-butenyl)phosphine oxide;

[0323] 2-propynyl methyl(2-propenyl)phosphinate, 2-propynyl 2-butenyl(methyl)phosphinate, 2-propynyl di(2-propenyl)phosphinate, 2-propynyl di(3-butenyl)phosphinate, 1,1-dimethyl-2-propynyl methyl(2-propenyl)phosphinate, 1,1-dimethyl-2-propynyl 2-butenyl(methyl)phosphinate, 1,1-dimethyl-2-propynyl di(2-propenyl)phosphinate, and Phosphinic acid esters such as 1,1-dimethyl-2-propynyl di(3-butenyl)phosphinate, 2-propenyl methyl(2-propynyl)phosphinate, 3-butenyl methyl(2-propynyl)phosphinate, 2-propenyl di(2-propynyl)phosphinate, 3-butenyl di(2-propynyl)phosphinate, 2-propynyl(2-propenyl)phosphinate, and 3-butenyl 2-propynyl(2-propenyl)phosphinate;

[0324] Methyl 2-propenyl phosphonate, methyl 2-butenyl phosphonate (2-propynyl), 2-propenylphosphonic acid (2-propynyl) (2-propenyl), 3-butenylphosphonic acid (3-butenyl) (2-propynyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl), and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), Phosphonic acid esters such as tylphosphonic acid (2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(2-propynyl), methylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl), ethylphosphonic acid (2-propynyl)(2-propenyl), ethylphosphonic acid (3-butenyl)(2-propynyl), ethylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), and ethylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl);

[0325] Phosphate esters such as (methyl)(2-propenyl)(2-propynyl) phosphate, (ethyl)(2-propenyl)(2-propynyl) phosphate, (2-butenyl)(methyl)(2-propynyl) phosphate, (1,1-dimethyl-2-propynyl)(methyl)(2-propenyl) phosphate, (1,1-dimethyl-2-propynyl)(ethyl)(2-propenyl) phosphate, (2-butenyl)(1,1-dimethyl-2-propynyl)(methyl) phosphate, and (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl) phosphate;

[0326] Of these, compounds having an alkynyloxy group are preferred because they form a negative electrode film more stably in the electrolyte.

[0327] Furthermore, compounds such as 2-propynylmethyl carbonate, di-2-propynyl carbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, methyl 2-propynyl oxalate, and di-2-propynyl oxalate are particularly preferred from the viewpoint of improving storage properties.

[0328] The compounds having the triple bond described above may be used individually or in any combination and ratio of two or more. There are no restrictions on the amount of the compounds having the triple bond to be incorporated into the total composition of this disclosure, and it is arbitrary as long as it does not significantly impair the effects of this disclosure. However, the compounds are usually included in the composition of this disclosure at a concentration of 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less. When the above range is met, the effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

[0329] In the compositions of this disclosure, an overcharge inhibitor can be used to effectively suppress battery rupture and ignition when an electrochemical device using the composition enters a state such as overcharging.

[0330] Overcharge prevention agents include unsubstituted or alkyl-substituted terphenyl derivatives such as biphenyl, o-terphenyl, m-terphenyl, and p-terphenyl; partially hydrogenated unsubstituted or alkyl-substituted terphenyl derivatives; cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindan, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, t-butylbenzene, t-amylbenzene, t-hexylbenzene, anisole, and other aromatic compounds; 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, o-cyclohexylfluorobenzene, p-cyclohexyl Examples include partially fluorinated compounds of the above aromatic compounds such as xylfluorobenzene, fluorotoluene, and benzotrifluoride; fluorinated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, and phenethylphenyl acetate; aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate; toluene derivatives such as toluene and xylene; and unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and o-cyclohexylbiphenyl. Among these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferred. Diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindan, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, and methylphenyl carbonate are also preferred.These may be used individually or in combination of two or more. When using two or more in combination, it is particularly preferable, from the viewpoint of balancing overcharge prevention characteristics and high-temperature storage characteristics, to use a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, or at least one selected from oxygen-free aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, and t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran.

[0331] The compositions of this disclosure may further comprise compound (5) represented by general formula (5).

[0332] General formula (5): [ka] (In the formula, A a+ is a metal ion, hydrogen ion, or onium ion. a is an integer from 1 to 3, b is an integer from 1 to 3, p is b / a, n203 is an integer from 1 to 4, n201 is an integer from 0 to 8, n202 is 0 or 1, Z 201 These are transition metals, elements of group III, IV, or V of the periodic table. X 201 This includes O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (alkylene groups, halogenated alkylene groups, arylene groups, and halogenated arylene groups may have substituents and heteroatoms in their structure, and when n202 is 1 and n203 is 2 to 4, there are X atoms in n203). 201 (These may be joined together.) L 201This includes halogen atoms, cyano groups, C1-C10 alkyl groups, C1-C10 halogenated alkyl groups, C6-C20 aryl groups, C6-C20 halogenated aryl groups (alkylene groups, halogenated alkylene groups, arylene groups, and halogenated arylene groups may have substituents and heteroatoms in their structure, and when n201 is 2-8, there are n201 L 201 (These may each join to form a ring) or -Z 203 Y 203 . Y 201 , Y 202 and Z 203 These are O, S, and NY, respectively, and are independent of each other. 204 , hydrocarbon group or fluorinated hydrocarbon group. Y 203 and Y 204 Each of these is independently H, F, a C1-C10 alkyl group, a C1-C10 halogenated alkyl group, a C6-C20 aryl group, or a C6-C20 halogenated aryl group (alkyl groups, halogenated alkyl groups, aryl groups, and halogenated aryl groups may have substituents or heteroatoms in their structure, Y 203 or Y 204 If multiple such elements exist, they may combine to form a ring.

[0333] A a+ Examples include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions, barium ions, cesium ions, silver ions, zinc ions, copper ions, cobalt ions, iron ions, nickel ions, manganese ions, titanium ions, lead ions, chromium ions, vanadium ions, ruthenium ions, yttrium ions, lanthanide ions, actinide ions, tetrabutylammonium ions, tetraethylammonium ions, tetramethylammonium ions, triethylmethylammonium ions, triethylammonium ions, pyridinium ions, imidazolium ions, hydrogen ions, tetraethylphosphonium ions, tetramethylphosphonium ions, tetraphenylphosphonium ions, triphenylsulfonium ions, and triethylsulfonium ions.

[0334] When used in applications such as electrochemical devices, A a+ Lithium ions, sodium ions, magnesium ions, tetraalkylammonium ions, and hydrogen ions are preferred, with lithium ions being particularly preferred. a+ The valence a of the cation is an integer between 1 and 3. If it is greater than 3, the crystal lattice energy increases, which makes it difficult to dissolve in the solvent. Therefore, if solubility is required, 1 is more preferable. Similarly, the valence b of the anion is an integer between 1 and 3, with 1 being particularly preferable. The constant p, which represents the ratio of the cation to the anion, is necessarily determined by the ratio of their valencies b / a.

[0335] Next, we will explain the ligand portion of general formula (5). In this specification, Z in general formula (5) 201 The organic or inorganic part that is bonded to the molecule is called a ligand.

[0336] Z 201 The element is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf, or Sb, and more preferably Al, B, or P.

[0337] X 201 represents O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene and arylene groups may have substituents and heteroatoms in their structure. Specifically, instead of hydrogen atoms on the alkylene and arylene groups, halogen atoms, linear or cyclic alkyl groups, aryl groups, alkenyl groups, alkoxy groups, aryloxy groups, sulfonyl groups, amino groups, cyano groups, carbonyl groups, acyl groups, amide groups, and hydroxyl groups may be present as substituents, or nitrogen, sulfur, and oxygen may be introduced instead of carbon atoms on the alkylene and arylene. Also, when n202 is 1 and n203 is 2 to 4, the X atoms in n203 201These components may be bonded together. An example of such a ligand is ethylenediaminetetraacetic acid.

[0338] L 201 This includes halogen atoms, cyano groups, C1-C10 alkyl groups, C1-C10 halogenated alkyl groups, C6-C20 aryl groups, C6-C20 halogenated aryl groups, or -Z 203 Y 203 (Z 203 , Y 203 (This will be explained later.) Here, alkyl and aryl groups also represent X 201 Similarly, the structure may have substituents and heteroatoms, and when n201 is 2 to 8, there are n201 L 201 Each of them may be joined together to form a ring. 201 Preferably, the element is a fluorine atom or a cyano group. In the case of a fluorine atom, the solubility and dissociation of the salt of the anionic compound are improved, and consequently, the ionic conductivity is improved. Furthermore, oxidation resistance is improved, which can suppress the occurrence of side reactions.

[0339] Y 201 , Y 202 and Z 203 These are O, S, and NY, respectively, and are independent of each other. 204 , represents a hydrocarbon group or a fluorinated hydrocarbon group. 201 and Y 202 is O, S or NY 204 It is preferable that it is O, and more preferably that it is O. A characteristic of compound (5) is that it contains Y in the same ligand. 201 and Y 202 Z by 201 Because of the bond with Z 201 It forms a chelate structure. This chelate effect improves the heat resistance, chemical stability, and hydrolysis resistance of this compound. The constant n202 in this ligand is 0 or 1, but in particular, when it is 0, the chelate ring becomes a five-membered ring, so the chelate effect is most strongly exhibited and stability is increased, which is preferable. In this specification, a fluorinated hydrocarbon group is defined as a hydrocarbon group in which at least one hydrogen atom is replaced by a fluorine atom.

[0340] Y 203 and Y 204 Each of these is independently H, F, a C1-C10 alkyl group, a C1-C10 halogenated alkyl group, a C6-C20 aryl group, or a C6-C20 halogenated aryl group, and these alkyl and aryl groups may have substituents or heteroatoms in their structure, and Y 203 or Y 204 If multiple such elements exist, they may combine to form a ring.

[0341] Furthermore, the constant n203 related to the number of ligands described above is an integer between 1 and 4, preferably 1 or 2, and more preferably 2. Also, the constant n201 related to the number of ligands described above is an integer between 0 and 8, preferably 0 to 4, and more preferably 0, 2, or 4. Moreover, it is preferable that when n203 is 1, n201 is 2, and when n203 is 2, n201 is 0.

[0342] In general formula (5), alkyl groups, alkyl halides, aryl groups, and aryl halides also include those having other functional groups such as branching, hydroxyl groups, and ether bonds.

[0343] Compound (5) has the general formula: [ka] (In the formula, A a+ a, b, p, n201, Z 201 and L 201 The compound shown above is, or the general formula: [ka] (In the formula, A a+ a, b, p, n201, Z 201 and L 201It is preferable that the compound is as shown above.

[0344] Compound (5) includes lithium oxalatoborate salts, which are given by the following formula: [ka] Lithium bis(oxalato)borate (LIBOB), represented by the following formula: [ka] Lithium difluorooxalatoborate (LIDFOB), represented by the following formula: [ka] Lithium difluorooxalatophosphanite (LIDFOP), represented by the following formula: [ka] Lithium tetrafluorooxalatophosphanite (LITFOP), represented by the following formula: [ka] Examples include lithium bis(oxalato)difluorophosphanite, as shown in the diagram.

[0345] Compound (5) also includes dicarboxylic acid complex salts in which the central complex element is boron, such as lithium bis(malonato)borate, lithium difluoro(malonato)borate, lithium bis(methylmalonato)borate, lithium difluoro(methylmalonato)borate, lithium bis(dimethylmalonato)borate, and lithium difluoro(dimethylmalonato)borate.

[0346] Examples of compound (5) also include dicarboxylic acid complex salts in which the central complex element is phosphorus, such as lithium tris(oxalato)phosphate, lithium tris(malonato)phosphate, lithium difluorobis(malonato)phosphate, lithium tetrafluoro(malonato)phosphate, lithium tris(methylmalonato)phosphate, lithium difluorobis(methylmalonato)phosphate, lithium tetrafluoro(methylmalonato)phosphate, lithium tris(dimethylmalonato)phosphate, lithium difluorobis(dimethylmalonato)phosphate, and lithium tetrafluoro(dimethylmalonato)phosphate.

[0347] Compound (5) also includes dicarboxylic acid complex salts in which the central element of the complex is aluminum, such as LiAl(C2O4)2 and LiAlF2(C2O4).

[0348] Among these, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate are more preferably used due to their availability and their ability to contribute to the formation of stable film-like structures. Lithium bis(oxalato)borate is particularly preferred as compound (5).

[0349] The content of compound (5) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, more preferably 10% by mass or less, and more preferably 3% by mass or less, relative to the solvent, in order to obtain even better cycling characteristics.

[0350] The compositions used in this disclosure may include carboxylic acid anhydrides (except for compound (2)). Compound (6), represented by the following general formula (6), is preferred as the carboxylic acid anhydride. The method for producing the carboxylic acid anhydride is not particularly limited, and any known method can be arbitrarily selected.

[0351] [ka] (In general formula (6), R 61 , R 62 Each of these independently represents a hydrocarbon group having 1 to 15 carbon atoms, which may have substituents.

[0352] R 61 , R 62 The type of monovalent hydrocarbon group is not particularly limited. For example, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain an unsaturated bond (carbon-carbon double bond or carbon-carbon triple bond). Furthermore, the aliphatic hydrocarbon group may be linear or cyclic, and if linear, it may be straight or branched. Moreover, it may be a combination of a linear and a cyclic structure. Note that R 61 and R 62 These may be identical or different from one another.

[0353] Also, R 61 , R 62 When the hydrocarbon group has substituents, the type of substituent is not particularly limited as long as it does not contradict the spirit of this disclosure, but examples include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms, and preferably fluorine atoms. Other substituents besides halogen atoms include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, and preferably cyano groups and carbonyl groups. 61 , R 62 The hydrocarbon group may have only one of these substituents or may have two or more. If it has two or more substituents, the substituents may be the same or different from one another.

[0354] R 61 , R 62The number of carbon atoms in each hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 12 or less, more preferably 10 or less, and even more preferably 9 or less. 61 and R 62 When R is bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms in that divalent hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 13 or less, more preferably 10 or less, and even more preferably 8 or less. 61 , R 62 If the hydrocarbon group has a substituent containing a carbon atom, then the R includes that substituent as well. 61 , R 62 It is preferable that the total number of carbon atoms satisfies the above range.

[0355] Next, specific examples of the above compound (6) will be described. In the following examples, "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure, to the extent that it does not contradict the spirit of this disclosure. Examples include dimers, trimers, and tetramers consisting of multiple acid anhydrides, or isostructural isomers having branched chains but the same number of carbon atoms in the substituents, or those in which the substituents are attached to the acid anhydride at different sites.

[0356] First, R 61 , R 62 The following are specific examples of acid anhydrides that are identical.

[0357] R 61 , R 62 Specific examples of acid anhydrides in which the chain alkyl group is included are acetic anhydride, propionic anhydride, butanoic anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2,2-dimethylbutanoic anhydride, 2,3-dimethylbutanoic anhydride, 3,3-dimethylbutanoic anhydride, 2,2,3-trimethylbutanoic anhydride, 2,3,3-trimethylbutanoic anhydride, 2,2,3,3-tetramethylbutanoic anhydride, 2-ethylbutanoic anhydride, and their analogues.

[0358] R61 , R 62 Specific examples of acid anhydrides in which the parent molecule is a cyclic alkyl group include cyclopropanecarboxylic acid anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, and their analogues.

[0359] R 61 , R 62 Specific examples of acid anhydrides in which the parent group is an alkenyl group include acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3-butenoic acid anhydride, 2-methyl-3-butenoic acid anhydride, 2,2-dimethyl-3-butenoic acid anhydride, 3-methyl-3-thenic acid anhydride, 2-methyl-3-methyl-3-butenoic acid anhydride, 2,2-dimethyl-3-methyl-3-butenoic acid anhydride, 3-pentenoic acid anhydride, 4-pentenoic acid anhydride, 2-cyclopentenecarboxylic acid anhydride, 3-cyclopentenecarboxylic acid anhydride, 4-cyclopentenecarboxylic acid anhydride, etc., and their analogues.

[0360] R 61 , R 62 Specific examples of acid anhydrides in which the parent group is an alkynyl group include propic anhydride, 3-phenylpropic anhydride, 2-butic anhydride, 2-pentic anhydride, 3-butic anhydride, 3-pentic anhydride, 4-pentic anhydride, and their analogues.

[0361] R 61 , R 62 Specific examples of acid anhydrides in which the group is an aryl group include benzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-ethylbenzoic acid anhydride, 4-tert-butylbenzoic acid anhydride, 2-methylbenzoic acid anhydride, 2,4,6-trimethylbenzoic acid anhydride, 1-naphthalenecarboxylic acid anhydride, 2-naphthalenecarboxylic acid anhydride, and their analogues.

[0362] Also, R 61 , R 62 Examples of acid anhydrides substituted with halogen atoms are listed below, primarily examples of acid anhydrides substituted with fluorine atoms. However, acid anhydrides obtained by substituting some or all of these fluorine atoms with chlorine atoms, bromine atoms, or iodine atoms are also included in the list of exemplary compounds.

[0363] R 61 , R 62 Examples of acid anhydrides in which the linear alkyl group is substituted with a halogen atom include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3-tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride, and their analogues.

[0364] R 61 , R 62 Examples of acid anhydrides in which the alkyl group is a cyclic alkyl group substituted with a halogen atom include 2-fluorocyclopentanecarboxylic acid anhydride, 3-fluorocyclopentanecarboxylic acid anhydride, 4-fluorocyclopentanecarboxylic acid anhydride, and their analogues.

[0365] R 61 , R 62Examples of acid anhydrides in which the nucleotide is an alkenyl group substituted with a halogen atom include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3-tris(trifluoromethyl)acrylic anhydride, and 2-(4-fluoro Examples include 2,3-(4-fluorophenyl)acrylic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butenoic acid anhydride, 2,2-difluoro-3-butenoic acid anhydride, 3-fluoro-2-butenoic acid anhydride, 4-fluoro-3-butenoic acid anhydride, 3,4-difluoro-3-butenoic acid anhydride, 3,3,4-trifluoro-3-butenoic acid anhydride, and their analogues.

[0366] R 61 , R 62 Examples of acid anhydrides in which the alkynyl group is substituted with a halogen atom include 3-fluoro-2-propynic anhydride, 3-(4-fluorophenyl)-2-propynic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propynic anhydride, 4-fluoro-2-butynic anhydride, 4,4-difluoro-2-butynic anhydride, 4,4,4-trifluoro-2-butynic anhydride, and their analogues.

[0367] R 61 , R 62 Examples of acid anhydrides in which the aryl group is substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and their analogues.

[0368] R 61 , R 62Examples of acid anhydrides having substituents with functional groups such as esters, nitriles, ketones, and ethers include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and their analogues.

[0369] Next, R 61 , R 62 The following are specific examples of acid anhydrides that are different from each other.

[0370] R 61 , R 62 The examples listed above, as well as all combinations of their related forms, are possible, but some representative examples are given below.

[0371] Examples of combinations of linear alkyl groups include propionic anhydride acetate, butanoic anhydride acetate, propionic butanoic anhydride, and 2-methylpropionic anhydride acetate.

[0372] Examples of combinations of linear alkyl groups and cyclic alkyl groups include cyclopentanoic anhydride acetate, cyclohexanoic anhydride acetate, and cyclopentanoic propionic anhydride acetate.

[0373] Examples of combinations of linear alkyl groups and alkenyl groups include acrylic anhydride acetate, 3-methylacrylic anhydride acetate, 3-butenic acid anhydride acetate, and propionic acid anhydride acetate.

[0374] Examples of combinations of linear alkyl groups and alkynyl groups include acetic acid propynic anhydride, acetic acid 2-butic anhydride, acetic acid 3-butic anhydride, acetic acid 3-phenylpropynic anhydride, propionic acid propynic anhydride, and the like.

[0375] Examples of combinations of linear alkyl groups and aryl groups include benzoic acid anhydride acetate, methylbenzoic acid anhydride acetate, 1-naphthalenecarboxylic acid anhydride acetate, and propionic acid benzoate anhydride.

[0376] Examples of combinations of linear alkyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride, trifluoroacetic anhydride, 4-fluorobenzoic anhydride, fluoroacetic acid propionic anhydride, alkyl oxalic acid anhydride, 2-cyanoacetic acid anhydride, 2-oxopropionic acid anhydride, methoxyacetic acid anhydride, methoxyacetic acid propionic anhydride, and the like.

[0377] Examples of combinations of cyclic alkyl groups include cyclopentanoic acid and cyclohexanoic anhydride, among others.

[0378] Examples of combinations of cyclic alkyl groups and alkenyl groups include cyclopentanoic anhydride acrylate, cyclopentanoic anhydride 3-methylacrylate, cyclopentanoic anhydride 3-butenoic anhydride, and cyclohexanoic anhydride acrylate.

[0379] Examples of combinations of cyclic alkyl groups and alkynyl groups include cyclopentanoic anhydride propynate, cyclopentanoic anhydride 2-butyrate, and cyclohexanoic anhydride propynate.

[0380] Examples of combinations of cyclic alkyl groups and aryl groups include cyclopentanoic anhydride benzoate, cyclopentanoic anhydride 4-methylbenzoic acid, and cyclohexanoic anhydride benzoate.

[0381] Examples of combinations of cyclic alkyl groups and hydrocarbon groups having functional groups include cyclopentanoic anhydride fluoroacetate, trifluoroacetic anhydride cyclopentanoic acid, 2-cyanoacetic anhydride cyclopentanoic acid, methoxyacetic anhydride cyclopentanoic acid, and fluoroacetic anhydride cyclohexanoic acid.

[0382] Examples of combinations of alkenyl groups include 2-methylacrylic anhydride acrylate, 3-methylacrylic anhydride acrylate, 3-butenic acid anhydride acrylate, and 3-methylacrylic anhydride 2-methylacrylic acid.

[0383] Examples of combinations of alkenyl and alkynyl groups include acrylic acid propynic anhydride, acrylic acid 2-butynic anhydride, and 2-methylacrylic acid propynic anhydride.

[0384] Examples of combinations of alkenyl and aryl groups include acrylate benzoic anhydride, 4-methylbenzoic anhydride, and 2-methylacrylate benzoic anhydride.

[0385] Examples of combinations of alkenyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride of acrylate, trifluoroacetic anhydride of acrylate, 2-cyanoacetic anhydride of acrylate, methoxyacetic anhydride of acrylate, fluoroacetic anhydride of 2-methylacrylate, and the like.

[0386] Examples of combinations of alkynyl groups include 2-butyric anhydride of propyic acid, 3-butyric anhydride of propyic acid, and 3-butyric anhydride of 2-butyric acid.

[0387] Examples of combinations of alkynyl and aryl groups include benzoic acid propynic anhydride, 4-methylbenzoic acid propynic anhydride, and benzoic acid 2-butynic anhydride.

[0388] Examples of combinations of an alkynyl group and a hydrocarbon group having a functional group include fluoroacetic anhydride of propynate, trifluoroacetic anhydride of propynate, 2-cyanoacetic anhydride of propynate, methoxyacetic anhydride of propynate, fluoroacetic anhydride of 2-butyrate, and the like.

[0389] Examples of combinations of aryl groups include 4-methylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, and 1-naphthalenecarboxylic anhydride of 4-methylbenzoic acid.

[0390] Examples of combinations of aryl groups and hydrocarbon groups having functional groups include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, 4-methylbenzoic acid fluoroacetic anhydride, and the like.

[0391] Examples of combinations of hydrocarbon groups having functional groups include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, trifluoroacetic acid 2-cyanoacetic anhydride, and the like.

[0392] Among the acid anhydrides forming the above chain structure, preferred are acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, etc., acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride, 2,3-dimethylacrylic acid anhydride, 3,3-dimethylacrylic acid anhydride, 3-butenoic acid anhydride, 2-methyl-3-butenoic acid anhydride, propynic acid anhydride, 2-butic acid anhydride, benzoic acid anhydride, 2-methylbenzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-tert-butylbenzoic acid anhydride, trifluoroacetic acid anhydride, 3,3,3-trif The anhydride is oolopropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, and ethoxyformic anhydride; more preferably, the anhydride is acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, and ethoxyformic anhydride.

[0393] These compounds are preferable in that they can form a durable film by appropriately bonding with lithium oxalate salts, thereby improving charge-discharge rate characteristics, input / output characteristics, and impedance characteristics, especially after durability testing.

[0394] There are no restrictions on the molecular weight of the carboxylic acid anhydride mentioned above; it can be any molecular weight as long as it does not significantly impair the effects of this disclosure. However, it is usually 90 or more, preferably 95 or more, while it is usually 300 or less, preferably 200 or less. When the molecular weight of the carboxylic acid anhydride is within the above range, the increase in viscosity of the electrolyte can be suppressed, and the film density can be optimized, thereby appropriately improving durability.

[0395] Furthermore, there are no particular restrictions on the method of producing the above-mentioned carboxylic acid anhydrides, and they can be produced by any known method. Any one of the carboxylic acid anhydrides described above may be included alone in the non-aqueous electrolyte of this disclosure, or two or more may be included in any combination and ratio.

[0396] Furthermore, there are no particular restrictions on the content of the above-mentioned carboxylic acid anhydride in the composition of this disclosure, and it is optional as long as it does not significantly impair the effects of this disclosure. However, it is desirable to include it in the composition of this disclosure at a concentration of typically 0.01% by mass or more, preferably 0.1% by mass or more, and typically 5% by mass or less, preferably 3% by mass or less. When the content of the carboxylic acid anhydride is within the above range, the effect of improving cycle characteristics is more likely to occur, and the reactivity is suitable, which makes it easier to improve battery characteristics.

[0397] Other known additives may be used in the compositions of this disclosure. Other additives include hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexyl, cyclohexane, 2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tert-butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene, and fluorinated biphenyls; Carbonate compounds such as erythritol carbonate, spirobis-dimethylene carbonate, and methoxyethyl-methyl carbonate; Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxopentadecane, ethoxymethoxyethane, trimethoxymethane, glyme, and ethyl monoglyme; Ketone compounds such as dimethyl ketone, diethyl ketone, and 3-pentanone; Acid anhydrides such as 2-allyl succinic anhydride; Ester compounds such as dimethyl oxalate, diethyl oxalate, ethylmethyl oxalate, di(2-propynyl) oxalate, methyl 2-propynyl oxalate, dimethyl succinate, di(2-propynyl) glutarate, methyl formate, ethyl formate, 2-propynyl formate, 2-butyne-1,4-diyldiformate, 2-propynyl methacrylate, and dimethyl malonate; Amide compounds such as acetamide, N-methylformamide, N,N-dimethylformamide, and N,N-dimethylacetamide; Ethylene sulfate, vinylene sulfate, ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, diphenyl sulfone, N,N-dimethylmethanesulfonamide, N,N-diethylmethanesulfonamide, methyl vinylsulfonate, ethyl vinylsulfonate, allyl vinylsulfonate, propargyl vinylsulfonate, methyl allylsulfonate, ethyl allylsulfonate, allyl allylsulfonate, propargyl allylsulfonate, 1,2-bis(vinylsulfonyloxy)ethane, propanedisulfonic anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethanedisulfonic anhydride, methylenemethanedisulfonate, 2-propynyl methanesulfonate, pentenesulfite, pentafluorophenylmethanesulfonate, propylene sulfate, propylene sulfite, propane Insalton, butylene sulfite, butane-2,3-diyldimethanesulfonate, 2-butyne-1,4-diyldimethanesulfonate, 2-propynyl vinylsulfonic acid, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, 2-(methanesulfonyloxy)propionic acid 2-propynyl, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxy Sulfur-containing compounds such as 3-sulfo-propionic anhydride, trimethylene methane disulfonate, 2-methyltetrahydrofuran, trimethylene methane disulfonate, tetramethylene sulfoxide, dimethyl methane disulfonate, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, methyl ethylenebissulfonate, ethyl ethylenebissulfonate, ethylene sulfate, and thiophene 1-oxide; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide, nitromethane, nitroethane, and ethylenediamine; Trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, diethyl ethyl phosphonoethyl acetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphin oxide, triethylphosphin oxide, bis(2,2-difluoroethyl) phosphate, bis(2,2,3,3-tetrafluoroethyl) phosphate Oropropyl) 2,2,2-trifluoroethyl, bis(2,2,2-trifluoroethyl)methyl phosphate, bis(2,2,2-trifluoroethyl)ethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2-difluoroethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2,3,3-tetrafluoropropyl, tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, tris(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate, trioctyl phosphate, 2-phenyl phosphate Nylphenyldimethyl, 2-phenylphenyldiethyl phosphate, (2,2,2-trifluoroethyl)(2,2,3,3-tetrafluoropropyl)methyl phosphate, methyl 2-(dimethoxyphosphoryl) acetate, methyl 2-(dimethylphosphoryl) acetate, methyl 2-(diethoxyphosphoryl) acetate, methyl 2-(diethylphosphoryl) acetate, methyl methylenebisphosphonate, ethyl methylenebisphosphonate, methyl ethylenebisphosphonate, ethyl ethylenebisphosphonate, methyl butylenebisphosphonate Phosphorus-containing compounds such as ethyl butylenebisphosphonate, 2-propynyl 2-(dimethoxyphosphoryl) acetate, 2-propynyl 2-(dimethylphosphoryl) acetate, 2-propynyl 2-(diethoxyphosphoryl) acetate, 2-propynyl 2-(diethylphosphoryl) acetate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and trimethylsilyl polyphosphate; Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; Silane compounds such as dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titaniumtetrakis(trimethylsiloxide), titaniumtetrakis(triethylsiloxide), and tetramethylsilane; These are some examples. These can be used individually or in combination of two or more. By adding these additives, the volume retention characteristics and cycle characteristics after high-temperature storage can be improved. Among the other additives mentioned above, phosphorus-containing compounds are preferred, with tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite being particularly preferred.

[0398] The amount of other additives is not particularly limited and is arbitrary as long as it does not significantly impair the effects of the present disclosure. The amount of other additives is preferably 0.01% by mass or more, and also 5% by mass or less, of 100% by mass of the composition. Within this range, the effects of the other additives can be easily expressed, and situations such as a decrease in battery characteristics, such as high-load discharge characteristics, can be easily avoided. The amount of other additives is more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, even more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0399] The compositions of this disclosure may further contain, to the extent that they do not impair the effects of this disclosure, cyclic and linear carboxylic acid esters, ether compounds, nitrogen-containing compounds, boron-containing compounds, organosilicon-containing compounds, flame retardants, surfactants, dielectric additives, cycle and rate characteristic improvers, sulfone compounds, and the like as additives.

[0400] Examples of the above-mentioned cyclic carboxylic acid esters include those with a total of 3 to 12 carbon atoms in their structural formula. Specifically, examples include gamma-butyrolactone, gamma-valerolactone, gamma-macoractone, epsilon-caprolactone, and 3-methyl-γ-butyrolactone. Among these, gamma-butyrolactone is particularly preferred from the viewpoint of improving the properties of electrochemical devices due to an improved degree of lithium ion dissociation.

[0401] The amount of cyclic carboxylic acid ester used as an additive is usually preferably 0.1% by mass or more, more preferably 1% by mass or more, per 100% by mass of the solvent. Within this range, the electrical conductivity of the composition is improved, making it easier to enhance the high-current discharge characteristics of the electrochemical device. Alternatively, the amount of cyclic carboxylic acid ester can be preferably 10% by mass or less, more preferably 5% by mass or less. By setting such an upper limit, the viscosity of the electrolyte is kept within an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and the high-current discharge characteristics of the electrochemical device are made within a good range.

[0402] Furthermore, fluorinated cyclic carboxylic acid esters (fluorinated lactones) can also be suitably used as the above-mentioned cyclic carboxylic acid esters. Examples of fluorinated lactones include those of the following formula (C):

[0403] [ka]

[0404] (In the formula, X 15 ~X 20 The elements are the same or different, and both are -H, -F, -Cl, -CH3, or fluorinated alkyl groups; however, X 15 ~X 20 (At least one of them is a fluorinated alkyl group.) Examples include fluorine-containing lactones shown as follows.

[0405] X 15 ~X 20Examples of fluorinated alkyl groups include -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, and -CF(CF3)2. -CH2CF3 and -CH2CF2CF3 are preferred due to their high oxidation resistance and safety-enhancing effects.

[0406] X 15 ~X 20 If at least one of them is a fluorinated alkyl group, then -H, -F, -Cl, -CH3 or a fluorinated alkyl group is X 15 ~X 20 The substitution may occur at only one location or at multiple locations. Preferably, there are 1 to 3 locations, and more preferably 1 to 2 locations, from the viewpoint of good solubility of the electrolyte salt.

[0407] The substitution position of the fluorinated alkyl group is not particularly limited, but X is chosen because it yields a good synthesis yield. 17 and / or X 18 However, especially X 17 or X 18 It is preferable that X is a fluorinated alkyl group, particularly -CH2CF3 or -CH2CF2CF3. 15 ~X 20 The element is -H, -F, -Cl, or CH3, and -H is particularly preferred due to its good solubility as an electrolyte salt.

[0408] In addition to those shown in the above formula, other examples of fluorinated lactones include, for example, the following formula (D):

[0409] [ka]

[0410] (In the formula, A and B are either CX) 226 X 227 (X 226 and X 227(These are the same or different alkylene groups, which may have -H, -F, -Cl, -CF3, -CH3, or a hydrogen atom substituted with a halogen atom, or contain a heteroatom in the chain), and the other is an oxygen atom; Rf 12 X is a fluorinated alkyl group or fluorinated alkoxy group which may have an ether linkage; 221 and X 222 They are the same or different, and all are -H, -F, -Cl, -CF3, or CH3;X 223 ~X 225 (n=0 or 1) These alkyl groups may be the same or different, and may have -H, -F, -Cl, or hydrogen atoms substituted with halogen atoms, or may contain heteroatoms in the chain. Examples include fluorine-containing lactones, as shown in [reference].

[0411] The fluorine-containing lactone represented by formula (D) is shown in formula (E):

[0412] [ka]

[0413] (In the formula, A, B, Rf 12 , X 221 , X 222 and X 223 (This is the same as equation (D)) The five-membered ring structure shown is preferred because it is easy to synthesize and has good chemical stability. Furthermore, the combination of A and B yields the following formula (F):

[0414] [ka]

[0415] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 (This is the same as equation (D)) Fluorine-containing lactones represented by the following formula (G):

[0416] [ka]

[0417] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 (This is the same as equation (D)) There are fluorine-containing lactones, as shown by [this symbol].

[0418] Among these, the characteristics of the electrolyte in this disclosure are particularly improved by its ability to exhibit excellent properties such as high dielectric constant and high dielectric strength, as well as by its good solubility of the electrolyte salt and reduction of internal resistance.

[0419] [ka] These are some examples. By incorporating fluorinated cyclic carboxylic acid esters, effects such as improved ionic conductivity, enhanced safety, and improved stability at high temperatures can be obtained.

[0420] Examples of the above-mentioned chain-like carboxylic acid esters include those with a total of 3 to 7 carbon atoms in their structural formula. Specifically, examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, and isopropyl isobutyrate.

[0421] Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, and ethyl butyrate are preferred from the viewpoint of improving ionic conductivity by reducing viscosity.

[0422] The above ether compounds are preferably linear ethers having 2 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms. Examples of chain-like ethers having 2 to 10 carbon atoms include dimethyl ether, diethyl ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, diethoxymethane, dimethoxyethane, methoxyethoxyethane, diethoxyethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol, diethylene glycol dimethyl ether, pentaethylene glycol, triethylene glycol dimethyl ether, triethylene glycol, tetraethylene glycol, tetraethylene glycol dimethyl ether, and diisopropyl ether.

[0423] Examples of cyclic ethers having 3 to 6 carbon atoms include 1,2-dioxane, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, metaformaldehyde, 2-methyl-1,3-dioxolane, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-(trifluoroethyl)dioxolane, 2,2-bis(trifluoromethyl)-1,3-dioxolane, and their fluorinated compounds. Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and crown ether are preferred because they have high solvation ability to lithium ions and improve the degree of ion dissociation. Particularly preferred are dimethoxymethane, diethoxymethane, and ethoxymethoxymethane because they have low viscosity and provide high ionic conductivity.

[0424] Furthermore, other fluorinated ethers besides fluorinated ether (E) can also be suitably used as the ether compound.

[0425] Examples of nitrogen-containing compounds include nitriles, fluorinated nitriles, carboxylic acid amides, fluorinated carboxylic acid amides, sulfonic acid amides and fluorinated sulfonic acid amides, acetamides, and formamides. Additionally, 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxaziridinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide can also be used. However, nitrile compounds represented by the above general formulas (1a), (1b), and (1c) are not included in the list of nitrogen-containing compounds.

[0426] Examples of the boron-containing compounds mentioned above include borate esters such as trimethylborate and triethylborate, borate ethers, and alkyl borates.

[0427] Examples of the organosilicon-containing compounds mentioned above include (CH3)4-Si, (CH3)3-Si-Si(CH3)3, and silicone oil.

[0428] Examples of the above-mentioned flame retardants include phosphate esters and phosphazene compounds. Examples of the above-mentioned phosphate esters include fluorine-containing alkyl phosphate esters, non-fluorine alkyl phosphate esters, and aryl phosphate esters. Among these, fluorine-containing alkyl phosphate esters are preferred because they can exhibit flame retardant effects even in small amounts.

[0429] Examples of the phosphazene compounds mentioned above include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0430] Examples of the above-mentioned fluorine-containing alkyl phosphate esters include, specifically, the fluorine-containing dialkyl phosphate ester described in Japanese Patent Publication No. 11-233141, the cyclic alkyl phosphate ester described in Japanese Patent Publication No. 11-283669, or the fluorine-containing trialkyl phosphate ester.

[0431] Preferred non-combustible (flame retardant) agents include (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, and (HCF2CF2CH2)3P=O.

[0432] The above-mentioned surfactant may be a cationic surfactant, anionic surfactant, nonionic surfactant, or amphoteric surfactant, but it is preferable that it contains a fluorine atom in order to obtain good cycle characteristics and rate characteristics.

[0433] Examples of surfactants containing such fluorine atoms include the following formula (30): Rf 5 COO - M + (30) (In the formula, Rf 5 M is a fluorine-containing alkyl group that may contain ether bonds with 3 to 10 carbon atoms; + is Li + kaNa + , K + Or NHR'3 + (R' may be the same or different, and both are either hydrogen or an alkyl group with 1 to 3 carbon atoms.) Fluorine-containing carboxylates represented by the following formula (40): Rf 6 SO3 - M + (40) (In the formula, Rf 6 M is a fluorine-containing alkyl group that may contain ether bonds with 3 to 10 carbon atoms; + is Li + kaNa + , K + Or NHR'3 +(R' may be the same or different, and both are either hydrogen or an alkyl group with 1 to 3 carbon atoms.) A fluorine-containing sulfonate represented by [formula] is preferred.

[0434] The amount of the surfactant described above is preferably 0.01 to 2% by mass in the electrolyte, since this can reduce the surface tension of the electrolyte without degrading the charge-discharge cycle characteristics.

[0435] Examples of the above-mentioned high dielectric additives include sulfolane, methylsulfolane, γ-butyrolactone, and γ-valerolactone.

[0436] Examples of the cycle characteristic and rate characteristic improving agents mentioned above include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0437] Furthermore, the composition of this disclosure may be further combined with a polymer material to form a gel-like (plasticized) gel electrolyte.

[0438] Examples of such polymer materials include conventionally known polyethylene oxide and polypropylene oxide, and modified versions thereof (Japanese Patent Publication No. 8-222270, Japanese Patent Publication No. 2002-100405); polyacrylate polymers, polyacrylonitrile, and fluororesins such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer (Japanese Patent Publication No. 4-506726, Japanese Patent Publication No. 8-507407, Japanese Patent Publication No. 10-294131); and composites of these fluororesins and hydrocarbon resins (Japanese Patent Publication No. 11-35765, Japanese Patent Publication No. 11-86630). In particular, it is desirable to use polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer as polymer materials for gel electrolytes.

[0439] In addition, the compositions of this disclosure may also include ion-conducting compounds as described in Japanese Patent Application No. 2004-301934.

[0440] This ionic conductive compound is given by formula (101): A-(D)-B (101) [In the formula, D is from formula (201): -(D1) n -(FAE) m -(AE) p -(Y) q - (201) (In the formula, D1 is given by formula (2a):

[0441] [ka]

[0442] (wherein Rf is a fluorine-containing ether group which may have a crosslinkable functional group; R 10 (This refers to a group or bond that connects Rf to the main chain.) An ether unit having a fluorine-containing ether group in its side chain; FAE is given by equation (2b):

[0443] [ka]

[0444] (wherein Rfa is a hydrogen atom, and R is a fluorinated alkyl group which may have a crosslinkable functional group; R 11 (This refers to the group or bond that connects Rfa to the main chain.) An ether unit having a fluorinated alkyl group in its side chain; AE is given by equation (2c):

[0445] [ka]

[0446] (In the formula, R 13 R is a hydrogen atom, an alkyl group which may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group which may have a crosslinkable functional group, or an aromatic hydrocarbon group which may have a crosslinkable functional group; 12 is R 13 (A group or bond that connects to the main chain) The ether unit shown by; Y is given by equations (2d-1)~(2d-3):

[0447] [ka]

[0448] A unit containing at least one of the following; n is an integer from 0 to 200; m is an integer from 0 to 200; p is an integer from 0 to 10000; q is an integer from 1 to 100; however, n+m is not 0, and the order of combination of D1, FAE, AE, and Y is not specified. A and B are the same or different, and may contain a hydrogen atom, a fluorine atom and / or a crosslinkable functional group, an alkyl group, a phenyl group, a -COOH group, -OR (where R is a hydrogen atom or a fluorine atom and / or a crosslinkable functional group), an ester group, or a carbonate group (however, if the terminal of D is an oxygen atom, it is not a -COOH group, -OR, an ester group, or a carbonate group). This is an amorphous fluorine-containing polyether compound having a fluorine-containing group in its side chain, represented by [the formula shown].

[0449] The compositions of this disclosure may contain sulfone compounds. Preferred sulfone compounds are cyclic sulfones having 3 to 6 carbon atoms and chain sulfones having 2 to 6 carbon atoms. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0450] Examples of cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. Among these, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred from the viewpoint of dielectric constant and viscosity, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0451] As sulfolanes, sulfolanes and / or sulfolane derivatives (hereinafter, sulfolanes may also be abbreviated as "sulfolanes") are preferred. As sulfolane derivatives, those in which one or more hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with fluorine atoms or alkyl groups are preferred.

[0452] Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methylsulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 3-sulfolene, 5-fluoro-3-(trifluoromethyl)sulfolane, etc. are preferred because they have high ionic conductivity and high input / output.

[0453] In addition, chain-like sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, and perfluoroethyl methyl sulfone. Examples include ethyltrifluoroethyl sulfone, ethylpentafluoroethyl sulfone, di(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethylisopropyl sulfone, difluoromethylisopropyl sulfone, trifluoromethylisopropyl sulfone, trifluoroethyl-n-propyl sulfone, trifluoroethylisopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethylisopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, and pentafluoroethyl-t-butyl sulfone.

[0454] Among these, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethylisopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, and trifluoromethyl-t-butyl sulfone are preferred because they have high ionic conductivity and high input / output capabilities.

[0455] The content of the sulfone compound is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and usually 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less, in 100% by volume of the solvent. If the content of the sulfone compound is within the above range, it is easy to obtain effects that improve durability such as cycle characteristics and storage characteristics, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range, a decrease in electrical conductivity can be avoided, and the input / output characteristics and charge / discharge rate characteristics of the non-aqueous electrolyte secondary battery can be set to an appropriate range.

[0456] From the viewpoint of improving output characteristics, the compositions of this disclosure may also preferably include, as an additive, at least one compound (7) selected from the group consisting of lithium fluorophosphate salts (excluding LiPF6) and lithium salts having an S=O group. Furthermore, when compound (7) is used as an additive, it is preferable to use a compound other than compound (7) as the electrolyte salt mentioned above.

[0457] Examples of lithium fluorophosphate salts include lithium monofluorophosphate (LiPO3F) and lithium difluorophosphate (LiPO2F2). Examples of lithium salts having the above-mentioned S=O group include lithium monofluorosulfonate (FSO3Li), lithium methyl sulfate (CH3OSO3Li), lithium ethyl sulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethyl sulfate. Among the compounds (7), LiPO2F2, FSO3Li, and C2H5OSO3Li are preferred.

[0458] The content of compound (7) is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, even more preferably 0.1 to 10% by mass, and particularly preferably 0.1 to 7% by mass, relative to the above composition.

[0459] The compositions of this disclosure may optionally contain other additives. Examples of other additives include metal oxides and glass.

[0460] The compositions of this disclosure preferably contain, as additives, at least one selected from the group consisting of unsaturated cyclic carbonates, compound (2), nitrile compounds, fluorinated saturated cyclic carbonates, lithium salts having an S=O group, lithium imide salts, lithium fluorophosphate salts (excluding LiPF6), and compound (5). Including these additives can further suppress the increase in resistance during high-temperature storage. The above additive is preferably at least one selected from the group consisting of unsaturated cyclic carbonate, compound (4), nitrile compound represented by general formula (1a), fluorinated saturated cyclic carbonate, lithium sulfonate compound, LiN(FSO2)2, lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LIBOB), and lithium difluorooxalatoborate (LIDFOB). It is even more preferable that it be at least one selected from the group consisting of vinylene carbonate, vinylethylene carbonate, maleic anhydride, adiponitrile, fluoroethylene carbonate, FSO3Li, LiN(FSO2)2, LiPO2F2, LIBOB, and LIDFOB.

[0461] The composition of this disclosure preferably contains 1 to 1000 ppm of hydrogen fluoride (HF). The inclusion of HF promotes the film formation of the additives described above. If the HF content is too low, the film formation ability on the negative electrode decreases, and the properties of the electrochemical device tend to deteriorate. Conversely, if the HF content is too high, the oxidation resistance of the electrolyte tends to decrease due to the influence of HF. Even when the composition of this disclosure contains HF within the above range, it does not reduce the high-temperature storage recovery capacity rate of the electrochemical device. The HF content is more preferably 5 ppm or more, even more preferably 10 ppm or more, and particularly preferably 20 ppm or more. The HF content is also more preferably 200 ppm or less, even more preferably 100 ppm or less, even more preferably 80 ppm or less, and particularly preferably 50 ppm or less. The HF content can be measured by neutralization titration.

[0462] The compositions of this disclosure may be prepared by any method using the components described above.

[0463] The compositions of this disclosure can be suitably applied to secondary batteries such as lithium-ion secondary batteries, electrochemical devices such as lithium-ion capacitors, hybrid capacitors, and electric double-layer capacitors. A non-aqueous electrolyte battery using the compositions of this disclosure will be described below. The above-described non-aqueous electrolyte battery can adopt a known structure and typically comprises a positive electrode and a negative electrode capable of intercalating and releasing ions (e.g., lithium ions), and the composition (electrolyte) of the present disclosure. An electrochemical device comprising such a composition (electrolyte) of the present disclosure is also part of the present disclosure.

[0464] Examples of electrochemical devices include secondary batteries such as lithium-ion secondary batteries, lithium-ion capacitors, capacitors (hybrid capacitors, electric double-layer capacitors), radical batteries, solar cells (especially dye-sensitized solar cells), lithium-ion primary batteries, fuel cells, various electrochemical sensors, electrochromic elements, electrochemical switching elements, aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc. Secondary batteries such as lithium-ion secondary batteries, lithium-ion capacitors, and electric double-layer capacitors are preferred. A module equipped with the above-mentioned electrochemical device is also one of the disclosures.

[0465] This disclosure also relates to a secondary battery comprising the composition (electrolyte) of this disclosure. The above-mentioned secondary battery preferably comprises a positive electrode, a negative electrode, and the aforementioned electrolyte. The above-mentioned secondary battery is preferably a lithium-ion secondary battery.

[0466] <Positive electrode> The positive electrode consists of a positive electrode active material layer containing positive electrode active material and a current collector.

[0467] The positive electrode active material is not particularly limited as long as it is electrochemically capable of intercalating and releasing lithium ions, but examples include lithium-containing transition metal composite oxides, lithium-containing transition metal phosphate compounds, sulfur-based materials, and conductive polymers. Among these, lithium-containing transition metal composite oxides and lithium-containing transition metal phosphate compounds are preferred as positive electrode active materials, and lithium-containing transition metal composite oxides that produce high voltage are particularly preferred.

[0468] Preferred transition metals for lithium-containing transition metal composite oxides include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include lithium-cobalt composite oxides such as LiCoO2, lithium-nickel composite oxides such as LiNiO2, lithium-manganese composite oxides such as LiMnO2, LiMn2O4, and Li2MnO4, and those in which some of the transition metal atoms that make up the main body of these lithium transition metal composite oxides are substituted with other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. A specific example of a substituted element is, for example, LiNi 0.5 Mn 0.5 O2, LiLiLi 0.85 Co 0.10 Al 0.05 O2, LiLiLi 0.5 Co 0.2 Mn 0.3 O2, LiLiLi 0.6 Co 0.2 Mn 0.2 O2, LiLiLi 0.33 Co 0.33 Mn 0.33 O2, LiLiLi 0.8 Co 0.1 Mn 0.1 O2, LiLiLi 0.45 Co 0.10 Al 0.45 O2, LiMn 1.8 Al 0.2 O4, LiMn 1.5 Ni 0.5 Examples include O4.

[0469] Among the lithium-containing transition metal composite oxides mentioned above, LiMn has a high energy density even at high voltages. 1.5 Ni 0.5 O4, LiSa 0.5 Co 0.2 Mn 0.3 O2, LiLiLi 0.6 Co 0.2 Mn 0.2 O2 is preferred. In particular, LiMn is preferred for high voltages of 4.4V or higher. 1.5 Ni 0.5 O4 is preferred.

[0470] Furthermore, among the lithium-containing transition metal composite oxides mentioned above, LiNi is particularly suitable because it can provide high-capacity lithium-ion secondary batteries. 0.6 Co 0.2 Mn 0.2 O2, LiLiLi 0.8 Co 0.1 Mn 0.1 O2, LiLiLi 0.85 Co 0.10 Al 0.05 O2 is preferred.

[0471] Preferred transition metals for lithium-containing transition metal phosphate compounds include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, cobalt phosphates such as LiCoPO4, and those in which some of the transition metal atoms that make up the main component of these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.

[0472] Examples of the above lithium-containing transition metal composite oxides include: Formula: Li a Mn 2-b M 1 b O4 (in the formula, 0.9≦a;0≦b≦1.5;M 1 Lithium manganese spinel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge. Formula:LiNi 1-c M 2 c O2 (where 0≦c≦0.5;M 2 (This refers to a lithium-nickel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), or Formula:LiCo 1-d M 3d O2 (where 0 ≦ d ≦ 0.5; M 3 is at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge). Examples thereof include lithium-cobalt composite oxides represented by the formula.

[0473] Among them, from the viewpoint of being able to provide a lithium-ion secondary battery with high energy density and high output, LiCoO2, LiMnO2, LiNiO2, LiMn2O4, LiNi 0.8 Co 0.15 Al 0.05 O2, or LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 is preferred.

[0474] As other positive electrode active materials, LiFePO4, LiNi 0.8 Co 0.2 O2, Li 1.2 Fe 0.4 Mn 0.4 O2, LiNi 0.5 Mn<~ 0.5 O2, LiV3O6, Li2MnO3, etc. can be mentioned.

[0475] Examples of the sulfur-based material include materials containing sulfur atoms, and at least one selected from the group consisting of elemental sulfur, metal sulfides, and organic sulfur compounds is preferred, and elemental sulfur is more preferred. The metal sulfide may be a metal polysulfide. The organic sulfur compound may be an organic polysulfide.

[0476] Examples of the metal sulfide include compounds represented by LiS x (0 < x ≦ 8); compounds represented by Li2S x (0 < x ≦ 8); compounds having a two-dimensional layered structure such as TiS2 and MoS2; Shubrel compounds having a strong three-dimensional skeleton structure represented by the general formula Me x Mo6S8 (Me is various transition metals including Pb, Ag, and Cu), etc.

[0477] Examples of the above-mentioned organic sulfur compounds include carbon sulfide compounds.

[0478] The above-mentioned organic sulfur compounds may be supported on a porous material such as carbon and used as a carbon composite material. The sulfur content in the carbon composite material is preferably 10 to 99% by mass, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 85% by mass or less, as this further improves cycle performance and reduces overpotential. If the positive electrode active material is elemental sulfur, the amount of sulfur contained in the positive electrode active material is equal to the amount of elemental sulfur.

[0479] Examples of conductive polymers include p-doped and n-doped conductive polymers. Other examples of conductive polymers include polyacetylene-based polymers, polyphenylene-based polymers, heterocyclic polymers, ionic polymers, ladder and network polymers, etc.

[0480] Furthermore, including lithium phosphate in the positive electrode active material is preferable because it improves continuous charging characteristics. There are no restrictions on the use of lithium phosphate, but it is preferable to use a mixture of the positive electrode active material and lithium phosphate. The amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, relative to the total amount of the positive electrode active material and lithium phosphate, with an upper limit of preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0481] Furthermore, a positive electrode active material may be used in which a substance of a different composition is attached to its surface. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0482] These surface-adhering substances can be attached to the surface of the positive electrode active material by, for example, dissolving or suspending them in a solvent and impregnating them into the positive electrode active material, followed by drying; dissolving or suspending a surface-adhering substance precursor in a solvent and impregnating it into the positive electrode active material, then reacting it by heating, etc.; or adding it to the positive electrode active material precursor and simultaneously firing it. In addition, when attaching carbon, a method of mechanically attaching carbonaceous material afterwards, for example in the form of activated carbon, can also be used.

[0483] The amount of surface-adhered material is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, relative to the positive electrode active material by mass, with an upper limit of preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. The surface-adhered material can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material, thereby improving battery life. However, if the amount of adhesion is too small, the effect will not be fully realized, and if it is too large, it may hinder the movement of lithium ions in and out, potentially increasing resistance.

[0484] The particle shapes of the positive electrode active material can include conventionally used shapes such as lumpy, polyhedral, spherical, ellipsoidal, plate-like, needle-like, and columnar. Furthermore, primary particles may aggregate to form secondary particles.

[0485] The tap density of the positive electrode active material is typically 1.5 g / cm³. 3 Preferably 2.0 g / cm³ 3 More preferably 2.5 g / cm³ 3In summary, the most preferred amount is 3.0 g / cm³. 3 The above is a summary. If the tap density of the positive electrode active material falls below the above lower limit, the amount of dispersion medium required during the formation of the positive electrode active material layer increases, as does the amount of conductive material and binder needed, which may restrict the filling rate of the positive electrode active material into the positive electrode active material layer and thus limit the battery capacity. By using metal composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, a higher tap density is preferable, and there is no particular upper limit, but it is usually 4.5 g / cm³. 3 Preferably 4.3 g / cm³ 3 The following applies: In this disclosure, the tap density is defined as the powder packing density (tap density) g / cm³ obtained when 5-10 g of positive electrode active material powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of approximately 20 mm. 3 We will seek it as follows.

[0486] The median diameter d50 of the positive electrode active material particles (or secondary particle diameter if primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more. It is also preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it falls below the lower limit, it may not be possible to obtain a high tap density product, and if it exceeds the upper limit, the diffusion of lithium within the particles will take longer, which may lead to a decrease in battery performance or cause problems such as streaking when creating the positive electrode of the battery, i.e., when slurrying the active material with conductive material and binder in a solvent and coating it into a thin film. Here, by mixing two or more of the above positive electrode active materials having different median diameters d50, the packing performance during positive electrode creation can be further improved.

[0487] In this disclosure, the median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using the HORIBA LA-920 as the particle size distribution analyzer, a 0.1% by mass aqueous solution of sodium hexametaphosphate is used as the dispersion medium during measurement, and the measurement is performed after ultrasonic dispersion for 5 minutes with the measurement refractive index set to 1.24.

[0488] When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and most preferably 2 μm or less. Exceeding the upper limit makes it difficult to form spherical secondary particles, which can adversely affect powder packing properties and significantly reduce the specific surface area, potentially leading to a decrease in battery performance such as output characteristics. Conversely, below the lower limit usually results in problems such as poor reversibility of charge and discharge due to underdeveloped crystals.

[0489] In this disclosure, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, it is determined by taking a photograph at 10,000x magnification, finding the longest value of the intercept between the left and right boundaries of the primary particle relative to a horizontal line for any 50 primary particles, and taking the average value.

[0490] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m². 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 The value is 1 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2 It is less than / g. If the BET specific surface area is smaller than this range, battery performance tends to decrease, and if it is larger, it becomes difficult to increase the tap density, which can cause problems with coating when forming the positive electrode active material layer.

[0491] In this disclosure, the BET specific surface area is defined as the value measured by a nitrogen adsorption BET single-point method using a gas flow method, after pre-drying the sample at 150°C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.), and then using a nitrogen-helium mixed gas that has been precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0492] When the secondary battery of this disclosure is used as a large lithium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required, so it is preferable that the particles of the positive electrode active material consist mainly of secondary particles. The positive electrode active material particles preferably contain 0.5 to 7.0 volume percent of fine particles with an average secondary particle diameter of 40 μm or less and an average primary particle diameter of 1 μm or less. By including fine particles with an average primary particle diameter of 1 μm or less, the contact area with the electrolyte is increased, which allows for faster diffusion of lithium ions between the electrode and the electrolyte, and as a result, the output performance of the battery can be improved.

[0493] For the production of positive electrode active materials, general methods for producing inorganic compounds are used. In particular, various methods can be considered for producing spherical or ellipsoidal active materials. For example, a method can be used in which transition metal raw materials are dissolved or pulverized and dispersed in a solvent such as water, the pH is adjusted while stirring to create and recover spherical precursors, these are dried as needed, and then a Li source such as LiOH, Li2CO3, or LiNO3 is added and calcined at a high temperature to obtain the active material.

[0494] For the manufacture of the positive electrode, the positive electrode active material may be used alone, or two or more materials with different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 Examples include combinations with LiMn2O4 such as O2, or in which part of the Mn is substituted with other transition metals, or combinations with LiCoO2, or in which part of the Co is substituted with other transition metals.

[0495] The content of the positive electrode active material described above is preferably 50 to 99.5% by mass of the positive electrode mixture, and more preferably 80 to 99% by mass, in order to achieve high battery capacity. Furthermore, the content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is too low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0496] The above positive electrode mixture preferably further includes a binder, a thickener, and a conductive material. As the binder mentioned above, any material can be used as long as it is safe for the solvent and electrolyte used during electrode manufacturing. Examples include: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, and nitrocellulose; rubbery polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or its hydrogenated additives; and EPDM (ethylene methyl phosphate). Examples include thermoplastic elastomer polymers such as ethylene-propylene-diene terpolymer, styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, or hydrogenated versions thereof; soft resin-like polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymer, and tetrafluoroethylene-ethylene copolymer; and polymer compositions having ionic conductivity for alkali metal ions (especially lithium ions). These may be used individually or in any combination and ratio of two or more types.

[0497] The binder content, as a percentage of the positive electrode active material layer, is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.2% by mass or more, and usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and most preferably 10% by mass or less. If the binder content is too low, the positive electrode active material cannot be sufficiently held, resulting in insufficient mechanical strength of the positive electrode and potentially degrading battery performance such as cycle characteristics. On the other hand, if it is too high, it may lead to a decrease in battery capacity and conductivity.

[0498] Examples of the thickening agents mentioned above include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, starch oxide, phosphated starch, casein, polyvinylpyrrolidone, and salts thereof. One of these may be used alone, or two or more may be used in any combination and ratio.

[0499] The ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and usually within the range of 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If it is below this range, the coating properties may be significantly reduced. If it is above this range, the proportion of active material in the positive electrode active material layer will decrease, which may lead to problems such as a decrease in battery capacity or an increase in resistance between positive electrode active materials.

[0500] Any known conductive material can be used as the conductive material. Specific examples include metal materials such as copper, nickel, and gold; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon materials such as needle coke, carbon nanotubes, fullerene, and amorphous carbon such as VGCF. These may be used individually or in any combination and ratio of two or more materials. The conductive material is usually contained in the positive electrode active material layer in an amount of 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less, and more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0501] The solvent used to form the slurry is not particularly limited in type, as long as it is capable of dissolving or dispersing the positive electrode active material, conductive material, binder, and thickener used as needed. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and a mixture of alcohol and water. Examples of organic solvents include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide.

[0502] Suitable materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or their alloys; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0503] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal for metal materials, and carbon plates, carbon thin films, and carbon cylinders for carbon materials. Of these, metal thin films are preferred. The thin film may be formed in a mesh shape as appropriate. The thickness of the thin film is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the thin film is thinner than this range, it may lack the necessary strength as a current collector. Conversely, if the thin film is thicker than this range, its handling may be impaired.

[0504] Furthermore, it is preferable that a conductive additive is applied to the surface of the current collector, from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of conductive additives include carbon and precious metals such as gold, platinum, and silver.

[0505] The ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is preferably 20 or less, more preferably 15 or less, most preferably 10 or less, and also preferably 0.5 or more, more preferably 0.8 or more, most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heating during high current density charging and discharging. If it falls below this range, the volume ratio of the current collector to the positive electrode active material increases, which may reduce the battery capacity.

[0506] The positive electrode can be manufactured by conventional methods. For example, the positive electrode active material can be mixed with the aforementioned binder, thickener, conductive material, solvent, etc., to form a slurry-like positive electrode mixture, which can then be applied to a current collector, dried, and pressed to increase its density.

[0507] The above-mentioned densification can be achieved by hand pressing, roller pressing, etc. The density of the positive electrode active material layer is preferably 1.0 g / cm³. 3 More preferably 1.3 g / cm³ 3 More preferably 1.5 g / cm³ 3 The above is true, and preferably 5 g / cm³ 3 More preferably, 3.0 g / cm³ 3 More preferably, 2.5 g / cm³ 3 The range is as follows. If the range is exceeded, the penetration of the electrolyte near the current collector / active material interface decreases, which can reduce charge / discharge characteristics, especially at high current densities, and may prevent high output from being obtained. Conversely, if the range is below this, the conductivity between the active materials decreases, increasing battery resistance and potentially preventing high output from being obtained.

[0508] When using the composition of this disclosure, from the viewpoint of increasing high power output and stability at high temperatures, it is preferable that the area of ​​the positive electrode active material layer be large relative to the outer surface area of ​​the battery casing. Specifically, it is preferable that the sum of the electrode areas of the positive electrode relative to the surface area of ​​the secondary battery casing be 15 times or more in area ratio, and more preferably 40 times or more. The outer surface area of ​​the battery casing refers to the total area calculated from the length, width, and thickness of the case portion filled with the power generation elements, excluding the terminal protrusions, in the case of a bottomed rectangular shape. In the case of a bottomed cylindrical shape, it is the geometric surface area approximating the case portion filled with the power generation elements, excluding the terminal protrusions, as a cylinder. The sum of the electrode areas of the positive electrode refers to the geometric surface area of ​​the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in a structure in which positive electrode mixture layers are formed on both sides via a current collector foil, it refers to the sum of the areas calculated separately for each surface.

[0509] The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer, after subtracting the thickness of the metal foil of the core material, is preferably 10 μm or more, more preferably 20 μm or more, and preferably 500 μm or less, and more preferably 450 μm or less, as a lower limit for one side of the current collector.

[0510] Furthermore, a positive electrode plate with a substance of a different composition attached to its surface may also be used. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0511] <Negative electrode> The negative electrode consists of a negative electrode active material layer containing the negative electrode active material and a current collector.

[0512] The negative electrode active material is not particularly limited as long as it is capable of electrochemically intercepting and releasing lithium ions. Specific examples include carbon materials, silicon materials, metallic materials, and conductive polymers. These may be used individually or in any combination of two or more materials.

[0513] Examples of the carbon materials mentioned above include natural graphite, artificial graphite, and those obtained by surface-treating these graphites with pitch or other organic substances and then carbonizing them. These may be used individually or in any combination of two or more types.

[0514] The silicon material mentioned above may be pure silicon, or it may be a composite material containing silicon and one or more other constituent elements (such as cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, boron, carbon, aluminum, phosphorus, etc.). These may be used individually or in any combination of two or more elements. In terms of obtaining excellent battery capacity, the silicon material mentioned above is SiO2. v (0 <v≦2)、SnO w (0≦w≦2), Si-Co-C composite materials and Si-Ni-C composite materials are preferred.

[0515] The silicon material described above is preferably used in combination with the carbon material described above. In this case, the mass ratio of silicon material to carbon material is preferably 1 to 20:99 to 80.

[0516] Examples of the above-mentioned metallic materials include metallic materials containing metallic elements such as lithium and tin. The above-mentioned metallic material may be a single metal, or a compound such as an alloy, oxide, carbide, nitride, silicide, sulfide, or phosphide. These may be used individually or in any combination of two or more. From the viewpoint of obtaining excellent battery capacity v, metallic materials containing lithium are preferred, and lithium metal (single-element lithium) is more preferred.

[0517] From the viewpoint of high current density charge-discharge characteristics, lithium-containing metal materials are preferred if they contain lithium and titanium, and lithium-titanium composite oxides (hereinafter abbreviated as "lithium-titanium composite oxide") are more preferred.

[0518] The above lithium titanium composite oxide has the general formula: Li x Ti y M z O4 [In the formula, M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb.] It is preferable that the compound is represented by [formula]. Among the above compositions, (i)1.2≦x≦1.4, 1.5≦y≦1.7, z=0 (ii)0.9≦x≦1.1, 1.9≦y≦2.1, z=0 (iii)0.7≦x≦0.9, 2.1≦y≦2.3, z=0 This structure is particularly preferable because it offers a good balance of battery performance.

[0519] A particularly preferred representative composition of the above compound is (i) Li 4 / 3 Ti 5 / 3 O4, (ii) Li1Ti2O4, (iii) Li4 / 5 Ti 11 / 5 It is O4. Also, regarding the structure Z≠0, for example, Li 4 / 3 Ti 4 / 3 Al 1 / 3 O4 is a preferred choice.

[0520] The above-mentioned negative electrode mixture preferably further includes a binder, a thickener, and a conductive material.

[0521] Examples of the binders mentioned above include those similar to the binders that can be used for the positive electrode as described above. The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less. If the ratio of the binder to the negative electrode active material exceeds the above range, the proportion of binder that does not contribute to the battery capacity increases, which may lead to a decrease in battery capacity. Also, if it falls below the above range, it may lead to a decrease in the strength of the negative electrode.

[0522] In particular, when a rubbery polymer such as SBR is included as the main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Furthermore, when a fluorine-based polymer such as polyvinylidene fluoride is included as the main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

[0523] Examples of the thickening agents mentioned above include those similar to the thickening agents that can be used in the positive electrode as described above. The ratio of the thickening agent to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If the ratio of the thickening agent to the negative electrode active material falls below the above range, the coating properties may be significantly reduced. If it exceeds the above range, the proportion of negative electrode active material in the negative electrode active material layer decreases, which may lead to problems such as a decrease in battery capacity or an increase in resistance between negative electrode active materials.

[0524] Examples of conductive materials for the negative electrode include metallic materials such as copper and nickel, and carbon materials such as graphite and carbon black.

[0525] The solvent used to form the slurry is not particularly limited in type, as long as it is capable of dissolving or dispersing the negative electrode active material, binder, and, if necessary, the thickener and conductive material. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and alcohol, while examples of organic solvents include N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N,N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphoramide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, and hexane.

[0526] Suitable materials for the negative electrode current collector include copper, nickel, and stainless steel. Among these, copper foil is preferred due to its ease of processing into a thin film and its cost-effectiveness.

[0527] The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less. If the thickness of the negative electrode current collector is too thick, the overall capacity of the battery may decrease too much, and conversely, if it is too thin, it may become difficult to handle.

[0528] The negative electrode can be manufactured by conventional methods. For example, one method involves adding the aforementioned binder, thickener, conductive material, solvent, etc., to the negative electrode material to form a slurry, applying it to a current collector, drying it, and then pressing it to increase its density. When using alloy materials, methods such as vapor deposition, sputtering, or plating can be used to form a thin film layer (negative electrode active material layer) containing the aforementioned negative electrode active material.

[0529] The electrode structure when the negative electrode active material is used as an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is 1 g·cm³. -3 The above is preferable, 1.2 g·cm -3 The above is even more preferable: 1.3 g·cm -3 The above is particularly preferable, and also 2.2 g·cm -3 The following is preferable: 2.1 g·cm -3 The following is more preferable: 2.0 g·cm -3 The following is even more preferable: 1.9 g·cm -3 The following are particularly preferable. If the density of the negative electrode active material present on the current collector exceeds the above range, the negative electrode active material particles may be destroyed, leading to an increase in the initial irreversible capacity and a deterioration of high-current-density charge-discharge characteristics due to reduced electrolyte permeability near the current collector / negative electrode active material interface. Conversely, if it falls below the above range, the conductivity between the negative electrode active materials decreases, increasing the battery resistance and potentially reducing the capacity per unit volume.

[0530] The thickness of the negative electrode plate is designed to match the positive electrode plate used and is not particularly limited, however, the thickness of the composite layer after subtracting the thickness of the core metal foil is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

[0531] Furthermore, a negative electrode plate with a substance of a different composition attached to its surface may also be used. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; and carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.

[0532] <Separator> The secondary battery of this disclosure preferably further comprises a separator. The material and shape of the separator described above are not particularly limited as long as they are stable in the electrolyte and have excellent liquid retention properties, and known materials can be used. In particular, it is preferable to use materials that are stable in the electrolyte, such as resins, glass fibers, or inorganic materials, and to use porous sheets or nonwoven fabrics that have excellent liquid retention properties.

[0533] As materials for the resin and glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters can be used. These materials, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films, may be used individually or in any combination and ratio of two or more. In particular, the separator is preferably a porous sheet or nonwoven fabric made from polyolefins such as polyethylene and polypropylene, as it has good electrolyte permeability and shut-off effect.

[0534] The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulating properties and mechanical strength may decrease. If it is too thick compared to the above range, not only may the battery performance such as rate characteristics decrease, but the energy density of the electrolyte battery as a whole may decrease.

[0535] Furthermore, when using porous materials such as porous sheets or nonwoven fabrics as separators, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, and usually 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too small compared to the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. Also, if it is too large compared to the above range, the mechanical strength of the separator tends to decrease and the insulating properties tend to deteriorate.

[0536] Furthermore, while the average pore size of the separator is arbitrary, it is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore size exceeds the above range, short circuits are more likely to occur. Conversely, if it falls below the above range, the film resistance increases and the rate characteristics may deteriorate.

[0537] On the other hand, inorganic materials such as oxides of alumina and silicon dioxide, nitrides of aluminum nitride and silicon nitride, and sulfates of barium sulfate and calcium sulfate are used, and these are available in particulate or fibrous form.

[0538] In terms of form, thin films such as nonwoven fabrics, woven fabrics, and microporous films are used. In the thin film form, those with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above independent thin film forms, a separator can be used in which a composite porous layer containing the above inorganic particles is formed on the surface of the positive electrode and / or negative electrode using a resin binder. For example, a porous layer can be formed on both sides of the positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0539] <Battery design> The electrode group may be either a laminated structure in which the positive electrode plate and the negative electrode plate are separated by the separator, or a structure in which the positive electrode plate and the negative electrode plate are spirally wound around the separator. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less.

[0540] If the electrode group occupancy rate falls below the above range, the battery capacity will decrease. Conversely, if it exceeds the above range, the void space is small, and the internal pressure increases due to the expansion of materials and the vapor pressure of the electrolyte liquid component as the battery heats up. This reduces various characteristics of the battery, such as its charge / discharge cycle performance and high-temperature storage capabilities, and may even cause the gas release valve that releases the internal pressure to activate.

[0541] The current collection structure is not particularly limited, but in order to more effectively improve the high-current-density charge-discharge characteristics using the electrolyte, it is preferable to have a structure that reduces the resistance of the wiring and connection parts. When the internal resistance is reduced in this way, the effect of using the electrolyte is particularly well exhibited.

[0542] In electrode groups with the above-described laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to a terminal is preferably used. When the area of ​​a single electrode is large, the internal resistance increases, so it is also preferable to provide multiple terminals within the electrode to reduce the resistance. In electrode groups with the above-described wound structure, the internal resistance can be lowered by providing multiple lead structures for both the positive and negative electrodes and bundling them to a terminal.

[0543] The material of the outer casing is not particularly limited as long as it is a stable material for the electrolyte used. Specifically, metals such as nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or laminated films of resin and aluminum foil can be used. From the viewpoint of weight reduction, aluminum or aluminum alloy metals or laminated films are preferably used.

[0544] Outer cases using metals may be sealed by welding the metals together using laser welding, resistance welding, or ultrasonic welding, or by using a crimped structure with the metals connected via a resin gasket. Outer cases using laminate film may be sealed by heat-fusing the resin layers together. To improve sealing performance, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when a sealed structure is formed by heat-fusing the resin layers via a current collector terminal, since it is a joint between metal and resin, a resin having polar groups or a modified resin with introduced polar groups is preferably used as the interposing resin.

[0545] The shape of the secondary battery disclosed herein is arbitrary and can include cylindrical, prismatic, laminated, coin-type, and large shapes. The shape and configuration of the positive electrode, negative electrode, and separator can be changed and used according to the shape of each battery.

[0546] A module equipped with the secondary battery described herein is also one of the disclosed items.

[0547] An electric double-layer capacitor comprising the composition of the present disclosure is also one of the present disclosures. The above-described electric double-layer capacitor may include a positive electrode, a negative electrode, and the aforementioned electrolyte. In the above-mentioned electric double-layer capacitor, at least one of the positive electrode and the negative electrode is a polarizable electrode, and the following electrodes, as described in detail in Japanese Patent Application Publication No. 9-7896, can be used as the polarizable electrode and the non-polarizable electrode.

[0548] The polarizing electrode mainly composed of activated carbon used in this disclosure preferably contains inert carbon with a large specific surface area and a conductive agent such as carbon black that imparts electronic conductivity. The polarizing electrode can be formed by various methods. For example, a polarizing electrode made of activated carbon and carbon black can be formed by mixing activated carbon powder, carbon black, and a phenolic resin, then press-molding and firing and activating the mixture in an inert gas atmosphere and a water vapor atmosphere. Preferably, this polarizing electrode is joined to a current collector with a conductive adhesive or the like.

[0549] Alternatively, activated carbon powder, carbon black, and a binder can be kneaded in the presence of alcohol, formed into a sheet, and dried to form a polarizable electrode. For example, polytetrafluoroethylene can be used as the binder. Alternatively, activated carbon powder, carbon black, a binder, and a solvent can be mixed to form a slurry, this slurry can be coated onto the metal foil of a current collector, and dried to form a polarizable electrode integrated with the current collector.

[0550] An electric double-layer capacitor may be constructed using polarizable electrodes mainly made of activated carbon at both electrodes. However, other configurations are also possible, such as one using a non-polarizable electrode on one side, for example, a configuration combining a positive electrode mainly made of a battery active material such as a metal oxide with a negative electrode made of a polarizable electrode mainly made of activated carbon, or a configuration combining a negative electrode made of a carbon material that can reversibly intercept and deintercept lithium ions, or a negative electrode made of lithium metal or a lithium alloy, with a polarizable positive electrode mainly made of activated carbon.

[0551] Alternatively, carbonaceous materials such as carbon black, graphite, expanded graphite, porous carbon, carbon nanotubes, carbon nanohorns, and Ketjenblack may be used instead of or in combination with activated carbon.

[0552] The non-polarizing electrode is preferably made mainly of a carbon material capable of reversibly intercepting and deintercepting lithium ions, and the electrode is made by intercepting lithium ions in this carbon material. In this case, a lithium salt is used as the electrolyte. With an electric double-layer capacitor of this configuration, an even higher withstand voltage exceeding 4V can be obtained.

[0553] The solvent used to prepare the slurry in electrode fabrication is preferably one that dissolves the binder, and depending on the type of binder, N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, dimethyl phthalate, ethanol, methanol, butanol, or water can be appropriately selected.

[0554] Activated carbon used in polarizing electrodes includes phenol resin-based activated carbon, coconut shell-based activated carbon, and petroleum coke-based activated carbon. Of these, petroleum coke-based activated carbon or phenol resin-based activated carbon is preferred because it allows for larger volumes to be obtained. Furthermore, there are various methods for activating activated carbon, such as steam activation and molten KOH activation, and it is preferred to use activated carbon produced by molten KOH activation because it allows for even larger volumes to be obtained.

[0555] Preferred conductive agents for polarizing electrodes include carbon black, Ketjen black, acetylene black, natural graphite, artificial graphite, metal fibers, conductive titanium oxide, and ruthenium oxide. The amount of conductive agent such as carbon black used in polarizing electrodes should preferably be 1 to 50% by mass of the total amount with activated carbon, in order to obtain good conductivity (low internal resistance) and to avoid reducing the volume of the product if too much is added.

[0556] Furthermore, the activated carbon used for polarizing electrodes has an average particle size of 20 μm or less and a specific surface area of ​​1500 to 3000 m², in order to obtain a large-capacity electric double-layer capacitor with low internal resistance. 2 It is preferable to use activated carbon with a concentration of / g. Furthermore, preferred carbon materials for constructing electrodes mainly composed of carbon materials capable of reversibly intercalating and detaching lithium ions include natural graphite, artificial graphite, graphitized mesocarbon spheres, graphitized whiskers, vapor-grown carbon fibers, fired products of furfuryl alcohol resin, or fired products of novolac resin.

[0557] The current collector can be any material that is chemically and electrochemically corrosion resistant. For polarizing electrodes mainly composed of activated carbon, stainless steel, aluminum, titanium, or tantalum are preferably used as the current collector. Of these, stainless steel or aluminum are particularly preferred materials in terms of both the characteristics and cost of the resulting electric double-layer capacitor. For electrodes mainly composed of carbon material capable of reversibly intercalating and detaching lithium ions, stainless steel, copper, or nickel are preferably used as the current collector.

[0558] Furthermore, to pre-intercept lithium ions in a carbon material capable of reversibly intercepting and detaching lithium ions, there are several methods: (1) mixing powdered lithium with a carbon material capable of reversibly intercepting and detaching lithium ions; (2) placing lithium foil on an electrode formed from a carbon material capable of reversibly intercepting and detaching lithium ions and a binder, and while electrically in contact with the electrode, immersing the electrode in an electrolyte containing a lithium salt to ionize the lithium and incorporate the lithium ions into the carbon material; and (3) placing the electrode formed from a carbon material capable of reversibly intercepting and detaching lithium ions and a binder on the negative side and lithium metal on the positive side, immersing it in a non-aqueous electrolyte containing a lithium salt as the electrolyte, and applying an electric current to electrochemically incorporate ionized lithium into the carbon material.

[0559] Commonly known types of electric double-layer capacitors include wound electric double-layer capacitors, laminated electric double-layer capacitors, and coin-type electric double-layer capacitors, and the electric double-layer capacitors mentioned above can also be of these types.

[0560] For example, a wound-type electric double-layer capacitor is assembled by winding a positive electrode and a negative electrode, which consist of a laminate of a current collector and an electrode layer (electrode), with a separator in between to create a wound element, placing this wound element in a case made of aluminum or the like, filling it with an electrolyte, preferably a non-aqueous electrolyte, and then sealing it with a rubber seal.

[0561] Conventional materials and compositions can be used as separators. Examples include polyethylene porous membranes, polytetrafluoroethylene, polypropylene fibers, glass fibers, and cellulose fiber nonwoven fabrics.

[0562] Furthermore, by known methods, laminate-type electric double-layer capacitors can be formed by stacking sheet-shaped positive and negative electrodes with an electrolyte and separator in between, or coin-type electric double-layer capacitors can be formed by fixing the positive and negative electrodes with a gasket and configuring them in a coin shape with an electrolyte and separator in between.

[0563] The compositions disclosed herein are useful as electrolytes for large lithium-ion secondary batteries for hybrid vehicles and distributed power sources, as well as for electric double-layer capacitors.

[0564] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Examples]

[0565] The present disclosure will now be explained with reference to examples, but the present disclosure is not limited to such examples.

[0566] (Fabrication and evaluation of lithium metal secondary batteries) [Preparation of electrolyte solution] The materials were mixed in the proportions shown in Table 1 to obtain a non-aqueous electrolyte.

[0567] [Fabrication of the positive electrode] Li(Ni) as a positive electrode active material 0.8 Mn 0.1 Co 0.1 97% by mass of O2(NMC811), 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to a 15 μm thick aluminum foil current collector, dried, and then compressed and molded using a press. The electrodes were cut into shapes with dimensions of 30 mm in width and 30 mm in length, and uncoated sections of 4 mm in width and 5 mm in length, to form the positive electrode.

[0568] [Fabrication of the negative electrode] As the negative electrode active material, a lithium foil with a thickness of 0.15 mm was cut to a width of 32 mm and a length of 32 mm, and then rolled onto a copper mesh having terminal sections of 33 mm in width, 33 mm in length, and 4 mm in width, and 5 mm in length using a PTFE roll to form the negative electrode.

[0569] [Preparation of laminated cells] As described above, the positive and negative electrodes were manufactured and stacked with a polypropylene separator in the order of negative electrode, separator, and positive electrode to create a battery element. This battery element was inserted into a bag made of a laminate film in which both sides of an aluminum sheet (thickness 40 μm) were coated with a resin layer, with the terminals of the positive and negative electrodes protruding. Then, the electrolytes of the examples and comparative examples in Table 1 were injected into the bag, and the bag was vacuum sealed to produce a pouch-type lithium metal secondary battery.

[0570] [Cycle Test] The laminate cells manufactured as described above were charged at 25°C with a current equivalent to 0.2C to 4.15V using constant current-constant voltage charging (hereinafter referred to as CC / CV charging) (0.05C cut-off), and then discharged to 3.0V with a constant current of 0.2C. This constituted one cycle, and five formation cycles were performed. Subsequently, 200 cycles of constant current-constant voltage charging at 0.5C and constant current discharge (between 4.15V and 3.0V) were performed in a constant temperature bath at 40°C. The ratio of the discharge capacity at 200 cycles to the discharge capacity at 40°C was calculated and defined as the cycle capacity retention rate (%). (Discharge capacity after 200 cycles) / (Discharge capacity in the first cycle) × 100 = Cycle capacity retention rate (%)

[0571] [Evaluation of gas generation amount] The volume of the battery before and after the cycle test was measured using the Archimedes method, and the amount of gas generated was determined from the volume change before and after the cycle. (Battery volume after cycle test) - (Battery volume before cycle test) = Gas generation amount (ml)

[0572] [Table 1]

[0573] (Fabrication and evaluation of lithium-ion secondary batteries) [Preparation of electrolyte solution] The materials were mixed in the proportions shown in Table 2 to obtain a non-aqueous electrolyte.

[0574] [Fabrication of the positive electrode] LiNi 0.5 Mn 1.5 A positive electrode slurry was prepared by mixing O4, acetylene black as the conductive material, and polyvinylidene fluoride (PVdF) N-methyl-2-pyrrolidone dispersion as the binder, so that the solid content ratio of the active material, conductive material, and binder was 92 / 3 / 5 (by mass). The obtained positive electrode slurry was uniformly applied to a 15 μm thick aluminum foil current collector, dried, and then compressed and molded using a press to form the positive electrode.

[0575] [Fabrication of the negative electrode] A negative electrode mixture slurry was prepared by mixing artificial graphite powder, SiO powder, an aqueous dispersion of sodium carboxymethylcellulose (1% by mass) as a thickener, and an aqueous dispersion of styrene-butadiene rubber (50% by mass) as a binder, in an aqueous solvent with a solid content ratio of 82.45 / 14.55 / 1.5 / 1.5 (by mass) of artificial graphite powder, SiO powder, thickener, and binder. This slurry was then uniformly coated onto a 10 μm thick copper foil, dried, and then compressed and formed using a press to create the negative electrode.

[0576] [Preparation of laminated cells] As described above, the positive and negative electrodes were manufactured and stacked with a polypropylene separator in the order of negative electrode, separator, and positive electrode to create a battery element. This battery element was inserted into a bag made of laminate film, which consists of an aluminum sheet (40 μm thick) coated on both sides with a resin layer, with the terminals of the positive and negative electrodes protruding. Then, the electrolytes of the examples and comparative examples in Table 2 were injected into the bag, and the bag was vacuum sealed to produce a pouch-type lithium-ion secondary battery.

[0577] [Cycle Test] The laminate cells manufactured as described above were CC / CV charged to 4.9V with a current equivalent to 0.1C at 25°C (0.05C cut-off), then discharged to 3.0V with a constant current of 0.1C. This constituted one cycle, and five formation cycles were performed. Subsequently, 200 cycles of constant current-constant voltage charging at 0.5C and constant current discharge (between 4.9V and 3.0V) were performed in a constant temperature bath at 40°C. The ratio of the discharge capacity at 200 cycles to the discharge capacity at 40°C was calculated and defined as the cycle capacity retention rate (%). (Discharge capacity after 200 cycles) / (Discharge capacity in the first cycle) × 100 = Cycle capacity retention rate (%)

[0578] [Evaluation of gas generation amount] The volume of the battery before and after the cycle test was measured using the Archimedes method, and the amount of gas generated was determined from the volume change before and after the cycle. (Battery volume after cycle test) - (Battery volume before cycle test) = Gas generation amount (ml)

[0579] [Table 2] The abbreviations used in the table are as follows: <Compound (A)> A-1: HCF2-CF2-O-CH2-CH2-OH A-2: HCF2-CF2-CH2-O-CH2-CH2-OH A-3: HCF2-CH2-O-CH2-CH2-OH A-4:CF3-CF2-CH2-O-CH2-CH2-OH A-5:CF3-CHF-CF2-O-CH2-CH2-OH A-6:HCF2-CF2-O-CH2-CH2-OLi A-7: HCF2-CF2-O-CH2-CH2-OK A-8:HCF2-CF2-O-CH2-CH2-ONa A-9: HCF2-CF2-O-CH2-CH2-OCs A-10:CF3-CHF-CF2-O-CH2-CH2-OLi <Fluorinated ether (E)> E-1:HCF2-CF2-O-CH2-CH2-O-CF2-CF2H E-2:HCF2-CF2-CH2-O-CH2-CH2-CH2-CF2-CF2H E-3:HCF2-CH2-O-CH2-CH2-O-CH2-CF2H E-4:CF3-CF2-CH2-O-CH2-CH2-O-CH2-CF2-CF3 E-5:CF3-CHF-CF2-O-CH2-CH2-O-CF2-CHF-CF3 E-6:HCF2-CF2-CH2-O-CF2-CF2H <Other solvent components> DME:CH3-O-CH2-CH2-O-CH3 EC: Ethylene carbonate DMC: Dimethyl carbonate FEC: Fluoroethylene carbonate TFMEC: Trifluoromethylethylene carbonate TFEMC:CF3-CH2-COO-CH3 (Trifluoroethylmethyl carbonate) <Lithium salts> LiFSI: Lithium bis(fluorosulfonyl)imide LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide LiPF6: Lithium hexafluorophosphate

Claims

1. It contains compound (A) represented by the following formula (A), The content of compound (A) is 0.0001 to 30000 ppm relative to the non-aqueous electrolyte composition. A composition for a non-aqueous electrolyte used in at least one electrochemical device selected from the group consisting of secondary batteries, lithium-ion capacitors, hybrid capacitors, and electric double-layer capacitors. (A)Rf １ -O-CH ２ -CH ２ -O-R １ (wherein, Rf １ R is a fluoroalkyl group having 1 to 6 carbon atoms. １ (These are H, Li, Na, K, or Cs.)

2. The Rf １ teeth, HCF ２ -CF ２ -、 HCF ２ -CF ２ -CH ２ -、 HCF ２ -CH ２ -、 CF ３ -CF ２ -CH ２ - or, CF ３ -CHF-CF ２ - The composition for non-aqueous electrolytes according to claim 1.

3. The aforementioned R １ The composition for non-aqueous electrolytes according to claim 1 or 2, wherein is H or Li.

4. The aforementioned compound (A) is HCF ２ -CF ２ -O-CH ２ -CH ２ -OH、 HCF ２ -CF ２ -O-CH ２ -CH ２ -OLi、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -OH, and, CF ３ -CHF-CF ２ -O-CH ２ -CH ２ The non-aqueous electrolyte composition according to claim 1 or 2, which is at least one selected from the group consisting of -OLi.

5. A non-aqueous electrolyte composition according to claim 1 or 2, comprising a fluorinated ether (E) represented by the following formula (E). (E)Rf ２ -O-R ２ (wherein, Rf ２ R is a fluoroalkyl group having 1 to 5 carbon atoms. ２ R is either H or an alkyl group having 1 to 6 carbon atoms. ２ The alkyl group may have an ether linkage and / or fluorine.

6. The Rf ２ HCF ２ -CF ２ - The composition for non-aqueous electrolytes according to claim 5.

7. The aforementioned R ２ teeth, -CH ２ -CH ２ -O-CF ２ -CF ２ H, or, -CH ２ -CH ２ -O-CF ２ -CHF-CF ３ The composition for non-aqueous electrolytes according to claim 5.

8. The fluorinated ether (E) is HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H、&、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -O-CF ２ -CHF-CF ３ The composition for non-aqueous electrolytes according to claim 5, which is at least one selected from the group consisting of the following.

9. The non-aqueous electrolyte composition according to claim 5, wherein the content of the fluorinated ether (E) is 0.01 to 99% by mass with respect to the non-aqueous electrolyte composition.

10. LiPF ６ The composition for a non-aqueous electrolyte according to claim 1 or 2, comprising at least one lithium salt selected from the group consisting of LiFSI and LiTFSI.

11. The aforementioned compound (A) is HCF ２ -CF ２ -O-CH ２ -CH ２ -OH、 HCF ２ -CF ２ -O-CH ２ -CH ２ -OLi、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -OH, and, CF ３ -CHF-CF ２ -O-CH ２ -CH ２ - At least one selected from the group consisting of OLi, The content of compound (A) is 0.003 to 30000 ppm relative to the non-aqueous electrolyte composition. HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H、&、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -O-CF ２ -CHF-CF ３ It comprises at least one fluorinated ether (E) selected from the group consisting of the following, The non-aqueous electrolyte composition according to claim 1 or 2, wherein the content of the fluorinated ether (E) is 0.5 to 50% by mass with respect to the non-aqueous electrolyte composition.

12. A composition for a non-aqueous electrolyte according to claim 11, and a secondary battery comprising lithium metal as a negative electrode active material.

13. Compound (A) is, HCF ２ -CF ２ -O-CH ２ -CH ２ -OH、 HCF ２ -CF ２ -O-CH ２ -CH ２ -OLi、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -OH, and, CF ３ -CHF-CF ２ -O-CH ２ -CH ２ - At least one selected from the group consisting of OLi, The content of compound (A) is 0.01 to 30,000 ppm relative to the non-aqueous electrolyte composition. HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H、&、 CF ３ -CHF-CF ２ -O-CH ２ -CH ２ -O-CF ２ -CHF-CF ３ It comprises at least one fluorinated ether (E) selected from the group consisting of the following, The non-aqueous electrolyte composition according to claim 1 or 2, wherein the content of the fluorinated ether (E) is 40 to 95% by mass with respect to the non-aqueous electrolyte composition.

14. A composition for a non-aqueous electrolyte according to claim 13, and a secondary battery comprising a silicon material as a negative electrode active material.

15. A non-aqueous electrolyte composition according to claim 1 or 2, for use in secondary batteries.

16. An electrochemical device comprising the non-aqueous electrolyte composition according to claim 1 or 2.

17. A secondary battery comprising the non-aqueous electrolyte composition according to claim 1 or 2.

18. A lithium-ion secondary battery comprising the non-aqueous electrolyte composition according to claim 1 or 2.

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