Electrolyte, Electrochemical Device, Lithium-Ion Secondary Battery, Module, and Compound

Abstract

Provided is an electrolytic solution or the like capable of reducing the resistance of an electrochemical device and improving the cycle properties thereof. This electrolytic solution includes a compound (1) represented by general formula (1) (in general formula (1), R101 is an organic group having 2-7 carbon atoms, and may have at least one selected from the group consisting of a heteroatom and an unsaturated bond. R102 is an organic group having 1-3 carbon atoms, and may have at least one selected from the group consisting of a heteroatom and an unsaturated bond).

Description

Technical Field

[0001] The present disclosure relates to an electrolytic solution, an electrochemical device, a lithium ion secondary battery, a module, and a compound.

Background Art

[0002] With the recent trend of weight reduction and miniaturization of electrical products, the development of electrochemical devices such as lithium ion secondary batteries with high energy density has been promoted. In addition, as the application fields of electrochemical devices such as lithium ion secondary batteries expand, improvement of characteristics has been demanded. In particular, in the future, when lithium ion secondary batteries are used for in-vehicle applications, improvement of battery characteristics will become even more important.

[0003] On the other hand, studies have been made to improve the characteristics of capacitors. For example, Patent Document 1 describes an electrolytic solution for an electric double layer capacitor containing ethyltrimethylammonium tetrafluoroborate and a specific imidazolium tetrafluoroborate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide an electrolytic solution capable of reducing the resistance of an electrochemical device and improving cycle characteristics, and an electrochemical device, a lithium ion secondary battery, and a module including the electrolytic solution. Another object of the present disclosure is to provide a novel compound.

Means for Solving the Problems

[0006] The present disclosure provides the following general formula (1): [Chemical formula] (In general formula (1), R 101 is an organic group having 2 to 7 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. R 102 is an organic group having 1 to 3 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds.) relates to an electrolytic solution containing compound (1) represented by the formula.

[0007] The content of compound (1) is preferably 0.001 to 10% by mass with respect to the above electrolytic solution.

[0008] The present disclosure relates to the following general formula (1-1): [Chemical formula] (In general formula (1-1), R 101 is an organic group having 2 to 7 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. R 102 is an organic group having 1 to 3 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds.) relates to an electrolytic solution containing cation (1-1) represented by the formula and bis(oxalato)borate anion.

[0009] The present disclosure also relates to an electrochemical device including the above electrolytic solution.

[0010] The present disclosure also relates to a lithium-ion secondary battery including the above electrolytic solution.

[0011] The present disclosure also relates to a module including the above electrochemical device or the above lithium-ion secondary battery.

[0012] The present disclosure relates to the following general formula (1): [Chemical formula] (In general formula (1), R101 is an organic group having 2 to 7 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. R 102 is an organic group having 1 to 3 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. The present invention also relates to a compound represented by the formula (). [Advantages of the Invention]

[0013] According to the present disclosure, it is possible to provide an electrolytic solution capable of reducing the resistance of an electrochemical device and improving cycle characteristics, an electrochemical device including the electrolytic solution, a lithium ion secondary battery, and a module. It is also possible to provide a novel compound. [Embodiments for Carrying Out the Invention]

[0014] Hereinafter, the present disclosure will be specifically described.

[0015] The present disclosure relates to an electrolytic solution (hereinafter, also referred to as a first electrolytic solution) containing a compound (1) represented by the following general formula (1): [Chemical Formula] (In the general formula (1), R 101 is an organic group having 2 to 7 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. R 102 is an organic group having 1 to 3 carbon atoms and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds.).

[0016] The first electrolyte of the present disclosure can reduce the resistance of electrochemical devices such as lithium-ion secondary batteries, and can also improve the cycle characteristics (for example, the capacity retention rate after cycling) of electrochemical devices. These effects are presumably due to the formation of a film of decomposition products of the above electrolyte on the electrodes of the electrochemical device. In particular, it is presumed that the resistance and cycle characteristics are improved by the formation of a film derived from the cation in the compound (1) on the positive electrode of the electrochemical device.

[0017] Compound (1) has the general formula (1):

Chemical formula

[0018] In the general formula (1), R 101 is an organic group having 2 to 7 carbon atoms, and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. The above organic group as R 101 is a divalent organic group. The carbon number of the above organic group is preferably 3 to 7, more preferably 4 to 7, still more preferably 4 or 5, and particularly preferably 4.

[0019] R 101 Examples of the above heteroatom in R include an oxygen atom (O), a sulfur atom (S), a nitrogen atom (N), a silicon atom (Si), a phosphorus atom (P), a boron atom (B), a halogen atom, etc. Preferably, it is an oxygen atom, a sulfur atom or a nitrogen atom, more preferably an oxygen atom or a nitrogen atom, and still more preferably an oxygen atom. R 101 may have an ether bond (-O-). R 101 It is also preferable that R has no heteroatom.

[0020] R 101The above unsaturated bond may be an unsaturated bond between carbon-carbon atoms, an unsaturated bond between carbon-hetero atoms, or an unsaturated bond between hetero atoms. It may also be a double bond or a triple bond. Examples of the above unsaturated bond include C=C, C≡C, C=O, C=N, C≡N, C=S, S=O, etc. R 101 Preferably, it does not have an unsaturated bond.

[0021] R 101 The above organic group as R preferably forms a 4- to 8-membered ring together with the sulfur atom in the general formula (1), more preferably forms a 5- to 8-membered ring, still more preferably forms a 5- to 6-membered ring, and particularly preferably forms a 5-membered ring. In the above organic group, it is preferable that the atoms constituting the ring are only carbon atoms.

[0022] R 101 is a group represented by -(CY 1 Y 2 ) n -(Y 1 and Y 2 are each independently a hydrogen atom or an organic group having 1 to 3 carbon atoms, and n is an integer of 2 to 7). Y 1 and Y 2 The above organic group as Y preferably has 1 to 2 carbon atoms, and more preferably has 1 carbon atom. Y 1 and Y 2 The above organic group as Y is preferably an alkyl group or an alkoxy group having a carbon number within the above range, and more preferably an alkyl group having a carbon number within the above range. Y 1 and Y 2 Preferably, they are hydrogen atoms. n is preferably an integer of 3 to 7, more preferably an integer of 4 to 7, still more preferably 4 or 5, and particularly preferably 4.

[0023] In the general formula (1), R102 is an organic group having 1 to 3 carbon atoms, and may have at least one selected from the group consisting of heteroatoms and unsaturated bonds. The number of carbon atoms of the above organic group is preferably 1 to 2, and more preferably 1.

[0024] R 102 Examples of the heteroatom in R include an oxygen atom (O), a sulfur atom (S), a nitrogen atom (N), a silicon atom (Si), a phosphorus atom (P), a boron atom (B), a halogen atom, etc. Preferably, it is an oxygen atom, a sulfur atom or a nitrogen atom, more preferably an oxygen atom or a nitrogen atom, and still more preferably an oxygen atom. R 102 may have an ether bond (-O-). R 102 Preferably, it does not have a heteroatom.

[0025] R 102 The unsaturated bond in R may be an unsaturated bond between carbon-carbon, an unsaturated bond between carbon-heteroatom, or an unsaturated bond between heteroatom-heteroatom. Also, it may be a double bond or a triple bond. Examples of the unsaturated bond include C=C, C≡C, C=O, C=N, C≡N, C=S, S=O, etc. R 102 Preferably, it does not have an unsaturated bond.

[0026] R 102 As R, an alkyl group having 1 to 3 carbon atoms which may have an ether bond is preferable, an alkyl group having 1 to 2 carbon atoms which may have an ether bond is more preferable, a methyl group (CH 3 ) or an ethyl group (CH 3 CH 2 ) is still more preferable, and a methyl group (CH 3 ) is particularly preferable.

[0027] As the compound (1), for example, a compound represented by the following formula can be exemplified.

Chemical formula

Chem.

Chem.

Chem.

[0028] As the compound (1), among others, the compound represented by the following formula is preferable.

Chem.

[0029] The compound (1) may be used alone or in combination of two or more.

[0030] The compound (1) is a novel compound. This disclosure also relates to the compound (1). In addition to being an electrolyte component of an electrolytic solution, the compound (1) can also be used as a functional compound such as an electrolyte of a solid battery, various actuators, a reaction medium, a catalyst for organic synthesis, etc. The use of the compound (1) as an electrolyte component is also one of the preferred embodiments. An additive for an electrolytic solution containing the compound (1) is also one of the preferred embodiments.

[0031] The compound (1) is, for example, the following general formula:

Chem.

Chem.

[0032] The amount of silver oxide in step (1) is preferably 0.1 to 3.0 molar equivalents, more preferably 0.5 to 2.0 molar equivalents, relative to compound (i).

[0033] The reaction in step (1) is preferably carried out in an alcohol solvent. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, etc. Among them, methanol is preferred.

[0034] The reaction in step (1) is preferably carried out in an inert gas atmosphere. Examples of the inert gas include argon gas, nitrogen gas, etc.

[0035] The reaction temperature in step (1) is preferably 0 to 50 °C, more preferably 10 to 30 °C.

[0036] The reaction time in step (1) is preferably 1 to 50 hours, more preferably 10 to 30 hours.

[0037] After step (1), steps such as filtration and concentration may be carried out as necessary.

[0038] The amount of boric acid in step (2) is preferably 0.1 to 3.0 molar equivalents, more preferably 0.5 to 2.0 molar equivalents, relative to compound (ii).

[0039] The amount of oxalic acid in step (2) is preferably 1.0 to 3.0 molar equivalents, more preferably 1.5 to 2.5 molar equivalents, relative to compound (ii).

[0040] The reaction of step (2) can be carried out in a solvent. As the above solvent, an organic solvent is preferred, and examples thereof include an alcohol solvent, a non-aromatic hydrocarbon solvent, an aromatic hydrocarbon solvent, a ketone solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a nitrile solvent, a sulfoxide-based solvent, and an amide solvent. Among them, an alcohol solvent is preferred, and methanol is more preferred. The above solvent can be used alone or in combination of two or more.

[0041] As the temperature of the reaction in step (2), 0 to 50 °C is preferred, and 10 to 30 °C is more preferred.

[0042] As the reaction time of step (2), 1 to 50 hours is preferred, and 10 to 30 hours is more preferred.

[0043] After step (2), steps such as filtration, concentration, and recrystallization may be carried out as necessary.

[0044] In the first electrolytic solution, the content of compound (1) is preferably 0.001 to 10% by mass based on the above electrolytic solution. When the content of compound (1) is within the above range, the resistance of the electrochemical device can be further reduced, and the cycle characteristics can be further improved. As the content of compound (1), more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more based on the above electrolytic solution. Also, more preferably 5.0% by mass or less, still more preferably 3.0% by mass or less, and particularly preferably 2.0% by mass or less.

[0045] This disclosure relates to the following general formula (1-1):

Chemical formula

[0046] The cation (1-1) has the general formula (1-1):

Chemical formula

[0047] Examples of the cation (1-1) include cations represented by the following formulas.

Chemical formula

Chemical formula

[0048] Among others, cations represented by the following formulas are preferred as the cation (1-1). [Chemical formula]

[0049] The cation (1-1) may be used alone or in combination of two or more.

[0050] The bis(oxalato)borate anion is represented by the following formula: [Chemical formula] It is the anion represented by.

[0051] In the second electrolyte, the molar ratio (a / b) of the content (a) of the cation (1-1) to the content (b) of the bis(oxalato)borate anion is preferably 0.001 to 20. By the molar ratio (a / b) being within the above range, the resistance of the electrochemical device can be further reduced, the cycle characteristics can be further improved, and the gas generation amount can be further reduced. As the molar ratio (a / b), 0.01 or more is more preferable, 0.1 or more is further preferable, 0.5 or more is even more preferable, and 0.9 or more is particularly preferable. Also, 15 or less is more preferable, 10 or less is further preferable, 5.0 or less is even more preferable, 2.0 or less is even more preferable, and 1.1 or less is particularly preferable.

[0052] In the second electrolyte, the content of the above cation (1-1) is preferably 0.0005 to 15% by mass with respect to the above electrolyte.

[0053] The contents of the cation (1-1) and the bis(oxalato)borate anion can be measured by NMR and liquid chromatography.

[0054] As the ion source that provides each ion contained in the second electrolyte, a compound containing each ion and soluble in the solvent constituting the electrolyte can be used. For the above ion sources, one kind or two or more kinds can be used respectively.

[0055] Examples of the ion source of the cation (1-1) include the above-described compound (1) and a compound composed of the cation (1-1) and a counter anion (excluding the bis(oxalato)borate anion). Examples of the above counter anion include PF 6 - , N(FSO 2 ) 2 - , N(CF 3 SO 2 ) 2 - , ClO 4 - , Cl - , BF 4 - and the like. PF 6 - , N(CF 3 SO 2 ) 2 - , BF 4 - are more preferable, and N(CF 3 SO 2 ) 2 - , BF 4 - are particularly preferable.

[0056] Examples of the ion source of the bis(oxalato)borate anion include the above-described compound (1) and a compound composed of the bis(oxalato)borate anion and a counter cation (excluding the cation (1-1)). Examples of the above counter cation include Li + , ammonium cation, pyridinium cation, pyrrolidinium cation, piperidinium cation, etc. Among them, Li + is preferable.

[0057] In terms of being able to further reduce the resistance of the electrochemical device, further improve the cycle characteristics, and further reduce the gas generation amount, it is preferable to use the compound (1) as the ion source for both the cation (1-1) and the bis(oxalato)borate anion.

[0058] The electrolytic solutions (the first and second electrolytic solutions) of the present disclosure preferably contain a solvent.

[0059] The above solvent preferably contains at least one selected from the group consisting of carbonates and carboxylic acid esters.

[0060] The above carbonate may be a cyclic carbonate or a chain carbonate.

[0061] The above cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0062] Examples of the above non-fluorinated cyclic carbonate include non-fluorinated saturated cyclic carbonates, and non-fluorinated saturated alkylene carbonates having an alkylene group with 2 to 6 carbon atoms are preferred, and non-fluorinated saturated alkylene carbonates having an alkylene group with 2 to 4 carbon atoms are more preferred.

[0063] Among them, as the above 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 in terms of high dielectric constant and suitable viscosity.

[0064] The above non-fluorinated saturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.

[0065] When the above non-fluorinated saturated cyclic carbonate is included, the content of the above non-fluorinated saturated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and still more preferably 15 to 45% by volume with respect to the above solvent.

[0066] The above-mentioned fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. A solvent containing the fluorinated cyclic carbonate can be suitably used even under a high voltage. In this specification, "high voltage" refers to a voltage of 4.2 V or more. Further, the upper limit of the "high voltage" is preferably 4.9 V.

[0067] The above-mentioned fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0068] The above-mentioned fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom. Specifically, it is represented by the following general formula (A):

[0069]

Chemical formula

[0070] When the above-mentioned fluorinated saturated cyclic carbonate is included, when the electrolyte of the present disclosure is applied to a high-voltage lithium-ion secondary battery or the like, the oxidation resistance of the electrolyte is improved, and stable and excellent charge-discharge characteristics can be obtained. In this specification, "ether bond" is a bond represented by -O-.

[0071] From the viewpoints of good dielectric constant and oxidation resistance, X 1 ~X 4 One or two of them are preferably -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond.

[0072] Since a decrease in viscosity at low temperatures, an increase in flash point, and further an improvement in the solubility of the electrolyte salt can be expected, X 1 ~X 4 is preferably -H, -F, a fluorinated alkyl group (a), a fluorinated alkyl group having an ether bond (b), or a fluorinated alkoxy group (c).

[0073] The above-mentioned fluorinated alkyl group (a) is one in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom. The number of carbon atoms of the fluorinated alkyl group (a) is preferably 1 to 20, more preferably 1 to 17, still more preferably 1 to 7, and particularly preferably 1 to 5. If the number of carbon atoms is too large, the low-temperature characteristics may deteriorate or the solubility of the electrolyte salt may decrease. If the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and further an increase in viscosity may be observed.

[0074] Among the above-mentioned fluorinated alkyl groups (a), those having 1 carbon atom include CFH 2 -, CF 2 H-, CF 3 -. In particular, CF 2 H- or CF 3 - is preferable in terms of high-temperature storage characteristics, and CF 3 - is most preferable.

[0075] Among the above-mentioned fluorinated alkyl groups (a), those having 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 a2An alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; provided that R a1 and R a2 at least one of which has a fluorine atom) is preferably exemplified from the viewpoint of good solubility of the electrolyte salt. In addition, R a1 and R a2 may further have other atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0076] R a1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. R a1 is preferably a linear or branched alkyl group having 1 to 16 carbon atoms. The number of carbon atoms of R a1 is more preferably 1 to 6, and even more preferably 1 to 3.

[0077] R a1 Specifically, as a linear or branched alkyl group, CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, CH 3 CH 2 CH 2 CH 2 -,

[0078]

Chemical formula

[0079] etc. can be mentioned.

[0080] Also, when R a1 is a linear alkyl group having a fluorine atom, CF 3 -, CF 3 CH 2 -, CF 3 CF 2 -, CF 3 CH 2 CH 2 -, CF 3 CF2 CH 2 -、CF 3 CF 2 CF 2 -、CF 3 CH 2 CF 2 -、CF 3 CH 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 -、CF 3 CH 2 CF 2 CH 2 -、CF 3 CF 2 CF 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 -、CF 3 CF 2 CH 2 CF 2 -、CF 3 CH 2 CH 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 CH 2 -、CF 3 CH 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 -、CF 3 CF 2 CH 2CH 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、HCF 2 -、HCF 2 CH 2 -、HCF 2 CF 2 -、HCF 2 CH 2 CH 2 -、HCF 2 CF 2 CH 2 -、HCF 2 CH 2 CF 2 -、HCF 2 CF 2 CH 2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 -、HCF 2 CF 2 CH 2 CH 2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 CH 2 -、FCH 2 -、FCH2 CH 2 -、FCH 2 CF 2 -、FCH 2 CF 2 CH 2 -、FCH 2 CF 2 CF 2 -、CH 3 CF 2 CH 2 -、CH 3 CF 2 CF 2 -、CH 3 CF 2 CH 2 CF 2 -、CH 3 CF 2 CF 2 CF 2 -、CH 3 CH 2 CF 2 CF 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CH 2 CH 2 -、CH 3 CH 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、HCFClCF 2 CH 2 -、HCF 2 CFClCH 2-、HCF 2 CFClCF 2 CFClCH 2 -、HCFClCF 2 CFClCF 2 CH 2 - etc. can be mentioned.

[0081] Also, when R a1 is a branched alkyl group having a fluorine atom,

[0082]

Chemical formula

[0083]

Chemical formula

[0084] etc. are preferably mentioned. However, CH 3 - or CF 3 - having such a branch tends to have high viscosity, so the number thereof is preferably small (1) or zero.

[0085] R a2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. R a2 may be linear or branched. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. R a2 is composed of these alone or in combination.

[0086] (i) Linear minimum structural unit: -CH 2 -、-CHF-、-CF 2 -、-CHCl-、-CFCl-、-CCl 2 -

[0087] (ii) Branched minimum structural unit:

[0088]

Chemical formula

[0089] Among the above examples, since the dehydrochlorination reaction by a base does not occur and it is more stable, it is preferably composed of structural units not containing Cl.

[0090] R a2 When it is linear, it consists only of the above-described linear minimum structural units. Among them, -CH 2 -, -CH 2 CH 2 - or -CF 2 - is preferred. From the viewpoint of further improving the solubility of the electrolyte salt, -CH 2 - or -CH 2 CH 2 - is more preferred.

[0091] R a2 When it is branched-chain, it contains at least one of the above-described branched-chain minimum structural units and is represented by the general formula -(CX a X b )- (where X a is H, F, CH 3 or CF 3 ; X b is CH 3 or CF 3 . However, when X b is CF 3 , X a is H or CH 3 ) are preferably exemplified. These can particularly further improve the solubility of the electrolyte salt.

[0092] Preferred fluorinated alkyl groups (a) include, for example, CF 3 CF 2 -, HCF 2 CF 2 -, H 2 CFCF 2 -, CH 3 CF 2 -, CF 3 CHF-, CH 3 CF 2 -3 CF 2 CF 2 -、HCF 2 CF 2 CF 2 -、H 2 CFCF 2 CF 2 -、CH 3 CF 2 CF 2 -、

[0093]

Chem.

[0094]

Chem.

[0095] etc. can be mentioned.

[0096] The fluorinated alkyl group (b) having the above ether bond is one in which at least one hydrogen atom of the alkyl group having the ether bond is replaced with a fluorine atom. The fluorinated alkyl group (b) having the above ether bond preferably has 2 to 17 carbon atoms. If the number of carbon atoms is too large, the viscosity of the above fluorinated saturated cyclic carbonate increases, and the number of fluorine-containing groups increases, so that a decrease in the solubility of the electrolyte salt due to a decrease in the dielectric constant and a decrease in the compatibility with other solvents may be observed. From this viewpoint, the number of carbon atoms of the fluorinated alkyl group (b) having the above ether bond is more preferably 2 to 10, and even more preferably 2 to 7.

[0097] The alkylene group constituting the ether moiety of the fluorinated alkyl group (b) having the above ether bond may be a linear or branched alkylene group. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below.

[0098] (i) Linear minimum structural unit: -CH 2 -、-CHF-、-CF 2-, -CHCl-, -CFCl-, -CCl 2 -

[0099] (ii) Branched-chain minimum structural unit:

[0100] [Chemical formula]

[0101] The alkylene group may be composed of these minimum structural units alone, or may be composed of linear (i) ones, branched-chain (ii) ones, or a combination of linear (i) and branched-chain (ii). Preferred specific examples will be described later.

[0102] Among the above examples, it is preferable to be composed of structural units not containing Cl because the dehydrochlorination reaction by a base does not occur and it is more stable.

[0103] More preferably, as the fluorinated alkyl group (b) having an ether bond, the general formula (b-1): R 3 -(OR 4 ) n1 - (b-1) (In the formula, R 3 may have a fluorine atom, preferably an alkyl group having 1 to 6 carbon atoms; R 4 may have a fluorine atom, preferably an alkylene group having 1 to 4 carbon atoms; n1 is an integer of 1 to 3; provided that at least one of R 3 and R 4 has a fluorine atom) is mentioned.

[0104] R 3 and R 4 can be exemplified as follows, and these can be appropriately combined to constitute the fluorinated alkyl group (b) having an ether bond represented by the above general formula (b-1), but it is not limited thereto.

[0105] (1) As R 3 , the general formula: Xc 3 C-(R 5 ) n2 -(three Xs c are the same or different and each is H or F; R 5 is an alkylene group which may have a fluorine atom and has 1 to 5 carbon atoms; n2 is 0 or 1) is preferable as the alkyl group.

[0106] When n2 is 0, examples of R 3 include CH 3 -, CF 3 -, HCF 2 - and H 2 CF-.

[0107] Specific examples when n2 is 1 are, when R 3 is linear, CF 3 CH 2 -, CF 3 CF 2 -, CF 3 CH 2 CH 2 -, CF 3 CF 2 CH 2 -, CF 3 CF 2 CF 2 -, CF 3 CH 2 CF 2 -, CF 3 CH 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH 2 -, CF 3 CH 2 CF 2 CH 2 -, CF 3 CF 2 CF 2 CH 2 -, CF 3 CF 2 CF 2 CF 2 -, CF 3 CF 2 CH 2 CF2 -、CF 3 CH 2 CH 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 CH 2 -、CF 3 CH 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、HCF 2 CH 2 -、HCF 2 CF 2 -、HCF 2 CH 2 CH 2 -、HCF 2 CF 2 CH 2 -、HCF 2 CH 2 CF 2 -、HCF 2 CF 2 CH2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 -、HCF 2 CF 2 CH 2 CH 2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 CH 2 -、FCH 2 CH 2 -、FCH 2 CF 2 -、FCH 2 CF 2 CH 2 -、CH 3 CF 2 -、CH 3 CH 2 -、CH 3 CF 2 CH 2 -、CH 3 CF 2 CF 2 -、CH 3 CH 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 -、CH 3 CF 2 CF 2 CF 2 -、CH 3 CH 2 CF 2 CF 2 -、CH 3CH 2 CH 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CH 2 CH 2 -、CH 3 CH 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、CH 3 CH 2 CF 2 CF 2 CH 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 - etc. can be exemplified.

[0108] When n2 is 1 and R 3 is a branched chain,

[0109]

Chemical formula

[0110] etc. can be mentioned.

[0111] However, since the viscosity tends to increase when it has branches such as CH 3 - or CF 3 -, those in which R 3 is a straight chain are more preferred.

[0112] (2) In the -(OR 4 ) n1 - in the general formula (b-1), n1 is an integer from 1 to 3, preferably 1 or 2. When n1 = 2 or 3, R 4 may be the same or different.

[0113] R 4 Preferred specific examples of may include the following linear or branched ones.

[0114] As the linear ones, -CH 2 -, -CHF-, -CF 2 -, -CH 2 CH 2 -, -CF 2 CH 2 -, -CF 2 CF 2 -, -CH 2 CF 2 -, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CF 2 -, -CH 2 CF 2 CH 2 -, -CH 2 CF 2 CF 2 -, -CF 2 CH 2 CH 2 -, -CF 2 CF 2 CH 2 -, -CF 2 CH 2 CF 2 -, -CF 2 CF 2 CF 2 - etc. can be exemplified.

[0115] As the branched ones,

[0116] [Chemical formula]

[0117] etc. can be mentioned.

[0118] The fluorinated alkoxy group (c) is one in which at least one hydrogen atom of the alkoxy group is substituted with a fluorine atom. The fluorinated alkoxy group (c) preferably has 1 to 17 carbon atoms. More preferably, it has 1 to 6 carbon atoms.

[0119] As the fluorinated alkoxy group (c), the general formula: X d 3 C-(R 6 ) n3 -O-(Three Xs d are the same or different, each being 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.

[0120] Specific examples of the fluorinated alkoxy group (c) include a fluorinated alkoxy group in which an oxygen atom is bonded to the end of the alkyl group exemplified as R 1 in the general formula (a-1).

[0121] 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 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 at low temperatures and the ignition point increase effect 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.

[0122] Also, in terms of good dielectric constant and oxidation resistance, the fluorine content of the above fluorinated saturated cyclic carbonate is preferably 10% by mass or more, more preferably 15% by mass or more. The upper limit is usually 76% by mass. The fluorine content of the above 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.

[0123] Specific examples of the above fluorinated saturated cyclic carbonate include, for example, the following.

[0124] X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate in which at least one of ~ is -F include

[0125]

Chemical formula

[0126] In addition,

[0127]

Chemical formula

[0128] etc. can also be used.

[0129] X 1 ~X 4 Specific examples of the fluorinated saturated cyclic carbonate in which at least one of ~ is a fluorinated alkyl group (a) and the rest are all -H include

[0130]

Chemical formula

[0131]

Chemical formula

[0132]

Chem.

[0133] etc. can be mentioned.

[0134] X 1 ~X 4 At least one of them is a fluorinated alkyl group (b) having an ether bond or a fluorinated alkoxy group (c), and specific examples of the fluorinated saturated cyclic carbonate in which the rest are all -H include

[0135]

Chem.

[0136]

Chem.

[0137]

Chem.

[0138]

Chem.

[0139]

Chem.

[0140]

Chem.

[0141] etc. can be mentioned.

[0142] Among them, the fluorinated saturated cyclic carbonate is preferably any of the following compounds.

[0143] [Chemical formula]

[0144] [Chemical formula]

[0145] Other examples of the fluorinated saturated cyclic carbonate 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, 4-ethyl-5,5-difluoro-1,3-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, 4,4-difluoro-1,3-dioxolan-2-one, and the like.

[0146] Among them, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethyl ethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropyl ethylene carbonate are more preferable as the fluorinated saturated cyclic carbonate.

[0147] The above fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom, and a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond is preferred. Specifically, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4-fluoro-5-vinyl ethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4,4-difluoro-4-vinyl ethylene carbonate, 4,4-difluoro-4-allyl ethylene carbonate, 4-fluoro-4-vinyl ethylene carbonate, 4-fluoro-4,5-diallyl ethylene carbonate, 4,5-difluoro-4-vinyl ethylene carbonate, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl ethylene carbonate, etc. may be mentioned.

[0148] The above fluorinated cyclic carbonate may be used alone, or two or more thereof may be used in combination at any combination and ratio.

[0149] When the above fluorinated cyclic carbonate is included, the content of the above fluorinated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and still more preferably 15 to 45% by volume with respect to the above solvent.

[0150] The above chain carbonate may be a non-fluorinated chain carbonate or a fluorinated chain carbonate.

[0151] Examples of the above non-fluorinated chain carbonate include, for example, CH 3 OCOOCH 3 (dimethyl carbonate: DMC), CH 3 CH 2 OCOOCH 2 CH 3 (diethyl carbonate: DEC), CH 3 CH 2 OCOOCH 3(Ethyl methyl carbonate: EMC), CH 3 OCOOCH 2 CH 2 CH 3 (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, ethyl phenyl carbonate and other hydrocarbon - based chain carbonates can be mentioned. Among them, it is preferably at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate and dimethyl carbonate.

[0152] The above non - fluorinated chain carbonate may be used alone or in combination of two or more in any combination and ratio.

[0153] When the above non - fluorinated chain carbonate is included, the content of the above non - fluorinated chain carbonate is preferably 10 - 90% by volume, more preferably 40 - 85% by volume, and still more preferably 50 - 80% by volume with respect to the above solvent.

[0154] The above fluorinated chain carbonate is a chain carbonate having a fluorine atom. A solvent containing a fluorinated chain carbonate can be preferably used even under high voltage.

[0155] Examples of the above fluorinated chain carbonate include the general formula (B): Rf 2 OCOOR 7 (B) (In the formula, Rf 2 is a fluorinated alkyl group having 1 - 7 carbon atoms, and R 7 is an alkyl group which may contain a fluorine atom and has 1 - 7 carbon atoms.) Compounds represented by this can be mentioned.

[0156] Rf 2 is a fluorinated alkyl group having 1 to 7 carbon atoms, and R 7 is an alkyl group which may contain a fluorine atom having 1 to 7 carbon atoms. The above fluorinated alkyl group is obtained by substituting at least one hydrogen atom of the alkyl group with a fluorine atom. When R 7 is an alkyl group containing a fluorine atom, it becomes a fluorinated alkyl group. Rf 2 and R 7 are preferably having 1 to 7 carbon atoms and more preferably 1 to 2 carbon atoms in terms of low viscosity. If the number of carbon atoms is too large, the low-temperature characteristics may deteriorate or the solubility of the electrolyte salt may decrease. If the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, or an increase in viscosity may be observed.

[0157] Examples of the fluorinated alkyl group having 1 carbon atom include CFH 2 -, CF 2 H-, CF 3 - and the like. In particular, CFH 2 - or CF 3 - is preferable in terms of high-temperature storage characteristics.

[0158] Examples of the fluorinated alkyl group having 2 or more carbon atoms include the following general formula (d-1): R d1 -R d2 - (d-1) (wherein R d1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom; R d2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; provided that at least one of R d1 and R d2 has a fluorine atom) can be preferably exemplified in terms of good solubility of the electrolyte salt. In addition, R d1 and R d2 may further have other atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0159] R d1 is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. R d1 is preferably a linear or branched alkyl group having 1 to 6 carbon atoms. R d1 More preferably, the number of carbon atoms of R is 1 to 3.

[0160] R d1 Specifically, as the linear or branched alkyl group, CH 3 -, CF 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, CH 3 CH 2 CH 2 CH 2 -,

[0161]

Chemical formula

[0162] etc. can be mentioned.

[0163] Also, when R d1 is a linear alkyl group having a fluorine atom, CF 3 -, CF 3 CH 2 -, CF 3 CF 2 -, CF 3 CH 2 CH 2 -, CF 3 CF 2 CH 2 -, CF 3 CF 2 CF 2 -, CF 3 CH 2 CF 2 -, CF 3 CH 2 CH 2 CH 2 -, CF 3 CF 2 CH 2 CH2 -、CF 3 CH 2 CF 2 CH 2 -、CF 3 CF 2 CF 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 -、CF 3 CF 2 CH 2 CF 2 -、CF 3 CH 2 CH 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 CH 2 -、CF 3 CH 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 CH 2 CH 2 -、CF 3 CF 2 CF 2 CF 2 CH 2 CH 2 -、CF 3 CF 2 CH 2 CF 2 CH 2 CH 2-、HCF 2 -、HCF 2 CH 2 -、HCF 2 CF 2 -、HCF 2 CH 2 CH 2 -、HCF 2 CF 2 CH 2 -、HCF 2 CH 2 CF 2 -、HCF 2 CF 2 CH 2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 -、HCF 2 CF 2 CH 2 CH 2 CH 2 -、HCF 2 CH 2 CF 2 CH 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 CH 2 CH 2 -、FCH 2 -、FCH 2 CH 2 -、FCH 2 CF 2 -、FCH 2 CF 2 CH 2 -、FCH 2 CF 2 CF 2 -、CH 3 CF 2 CH 2 -、CH 3 CF 2CF 2 -、CH 3 CF 2 CH 2 CF 2 -、CH 3 CF 2 CF 2 CF 2 -、CH 3 CH 2 CF 2 CF 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CF 2 CH 2 CH 2 -、CH 3 CH 2 CF 2 CF 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、CH 3 CF 2 CH 2 CF 2 CH 2 CH 2 -、HCFClCF 2 CH 2 -、HCF 2 CFClCH 2 -、HCF 2 CFClCF 2 CFClCH 2 -、HCFClCF 2 CFClCF 2 CH 2 - etc. can be mentioned.

[0164] Also, when R d1 is a branched-chain alkyl group having a fluorine atom,

[0165] [Chemical formula]

[0166] [Chemical formula]

[0167] etc. are preferably mentioned. However, since the viscosity tends to increase when it has a branch such as CH 3 - or CF 3 -, it is more preferable that the number is small (1) or zero because the viscosity is likely to increase.

[0168] R d2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom. R d2 may be linear or branched. An example of the minimum structural unit constituting such a linear or branched alkylene group is shown below. R d2 is composed of these alone or in combination.

[0169] (i) Linear minimum structural unit: -CH 2 -,-CHF-,-CF 2 -,-CHCl-,-CFCl-,-CCl 2 -

[0170] (ii) Branched minimum structural unit:

[0171] [Chemical formula]

[0172] Among the above examples, it is preferable to be composed of structural units not containing Cl because the dehydrochlorination reaction by a base does not occur and it is more stable.

[0173] R d2 When it is linear, it consists only of the above-mentioned linear minimum structural units, and among them, -CH2 -, -CH 2 CH 2 - or -CF 2 - is preferred. From the point that the solubility of the electrolyte salt can be further improved, -CH 2 - or -CH 2 CH 2 - is more preferred.

[0174] R d2 When it is branched, it contains at least one of the above-mentioned branched minimum structural units, and has the general formula -(CX a X b )-(X a is H, F, CH 3 or CF 3 ; X b is CH 3 or CF 3 . However, when X b is CF 3 , X a is H or CH 3 ). Those represented by this can be preferably exemplified. These can particularly further improve the solubility of the electrolyte salt.

[0175] Preferred fluorinated alkyl groups include, specifically, for example, CF 3 CF 2 -, HCF 2 CF 2 -, H 2 CFCF 2 -, CH 3 CF 2 -, CF 3 CH 2 -, CF 3 CF 2 CF 2 -, HCF 2 CF 2 CF 2 -, H 2 CFCF 2 CF 2 -, CH 3 CF 2 CF 2 -,

[0176]

Chemical formula

[0177]

Chemical

[0178] etc. can be mentioned.

[0179] Among them, when Rf 2 and R 7 are fluorinated alkyl groups, CF 3 -, CF 3 CF 2 -, (CF 3 ) 2 CH-, CF 3 CH 2 -, C 2 F 5 CH 2 -, CF 3 CF 2 CH 2 -, HCF 2 CF 2 CH 2 -, CF 3 CFHCF 2 CH 2 -, CFH 2 -, CF 2 H- are preferred. From the points of high flame retardancy, good rate characteristics and oxidation resistance, CF 3 CH 2 -, CF 3 CF 2 CH 2 -, HCF 2 CF 2 CH 2 -, CFH 2 -, CF 2 H- are more preferred.

[0180] When R 7 is an alkyl group not containing a fluorine atom, it is an alkyl group having 1 to 7 carbon atoms. R 7 is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably 1 to 3 carbon atoms, in terms of low viscosity.

[0181] Examples of the alkyl group without a fluorine atom include CH 3 -, CH 3 CH 2 -, (CH 3 ) 2 CH-, C 3 H 7 - and the like. Among them, CH 3 -, CH 3 CH 2 - are preferred in terms of low viscosity and good rate characteristics.

[0182] The fluorinated chain carbonate preferably has a fluorine content of 15 to 70% by mass. When the fluorine content is within the above range, the compatibility with the solvent and the solubility of the salt can be maintained. The above fluorine content is more preferably 20% by mass or more, still more preferably 30% by mass or more, particularly preferably 35% by mass or more, more preferably 60% by mass or less, and still more preferably 50% by mass or less. In the present disclosure, the fluorine content is based on the structural formula of the fluorinated chain carbonate, {(number of fluorine atoms × 19) / molecular weight of fluorinated chain carbonate} × 100 (%) which is the calculated value.

[0183] The fluorinated chain carbonate is preferably any of the following compounds in terms of low viscosity.

[0184]

Chemical formula

[0185] As the fluorinated chain carbonate, methyl 2,2,2-trifluoroethyl carbonate (F 3 CH 2 COC(=O)OCH 3 ) is particularly preferred.

[0186] The fluorinated chain carbonate may be used alone or in combination of two or more in any combination and ratio.

[0187] When the fluorinated chain carbonate is included, the content of the fluorinated chain carbonate is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and still more preferably 50 to 80% by volume with respect to the solvent.

[0188] The carboxylic acid ester may be a cyclic carboxylic acid ester or a chain carboxylic acid ester.

[0189] The cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0190] Examples of the non-fluorinated cyclic carboxylic acid ester 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.

[0191] Specific examples of the non-fluorinated saturated cyclic carboxylic acid ester 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 them, γ-butyrolactone and δ-valerolactone are particularly preferred in terms of improving the lithium ion dissociation degree and load characteristics.

[0192] The non-fluorinated saturated cyclic carboxylic acid ester may be used alone or in combination of two or more in any combination and ratio.

[0193] When the non-fluorinated saturated cyclic carboxylic acid ester is included, the content of the non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, still more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume with respect to the solvent.

[0194] The above-mentioned chain carboxylic acid ester may be a non-fluorinated chain carboxylic acid ester or a fluorinated chain carboxylic acid ester. When the above-mentioned solvent contains the above-mentioned chain carboxylic acid ester, an increase in resistance after high-temperature storage of the electrolytic solution can be further suppressed.

[0195] Examples of the non-fluorinated chain carboxylic acid ester 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 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, isobutyl acetate, and the like.

[0196] Among them, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0197] The above-mentioned non-fluorinated chain carboxylic acid ester may be used alone or in combination of two or more in any combination and ratio.

[0198] When the non-fluorinated chain carboxylic acid ester is included, the content of the non-fluorinated chain carboxylic acid ester is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, still more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume with respect to the solvent.

[0199] The fluorinated chain carboxylic acid ester is a chain carboxylic acid ester having a fluorine atom. A solvent containing the fluorinated chain carboxylic acid ester can be preferably used even under high voltage.

[0200] As the fluorinated chain carboxylic acid ester, the following general formula: R 31 COOR 32 (In the formula, R 31 and R 32 are each independently an alkyl group which may contain a fluorine atom having 1 to 4 carbon atoms, and at least one of R 31 and R 32 contains a fluorine atom.) The fluorinated chain carboxylic acid ester represented by the formula is preferable in terms of good compatibility with other solvents and oxidation resistance.

[0201] R 31 and R 32 include, for example, a methyl group (-CH 3 ), an ethyl group (-CH 2 CH 3 ), a propyl group (-CH 2 CH 2 CH 3 ), an isopropyl group (-CH(CH 3 ) 2 ), a normal butyl group (-CH 2 CH 2 CH 2 CH 3 ), a tertiary butyl group (-C(CH 3 ) 3 ) and other non-fluorinated alkyl groups; -CF 3 , -CF 2 H, -CFH 2 , -CF 2 CF3 , -CF 2 CF 2 H, -CF 2 CFH 2 , -CH 2 CF 3 , -CH 2 CF 2 H, -CH 2 CFH 2 , -CF 2 CF 2 CF 3 , -CF 2 CF 2 CF 2 H, -CF 2 CF 2 CFH 2 , -CH 2 CF 2 CF 3 , -CH 2 CF 2 CF 2 H, -CH 2 CF 2 CFH 2 , -CH 2 CH 2 CF 3 , -CH 2 CH 2 CF 2 H, -CH 2 CH 2 CFH 2 , -CF(CF 3 ) 2 , -CF(CF 2 H) 2 , -CF(CFH 2 ) 2 , -CH(CF 3 ) 2 , -CH(CF 2 H) 2 , -CH(CFH 2 ) 2 , -CF(OCH 3 )CF 3 , -CF 2 CF 2 CF 2 CF 3 , -CF 2 CF 2 CF 2 CF 2 H, -CF 2 CF2 CF 2 CFH 2 、 -CH 2 CF 2 CF 2 CF 3 、 -CH 2 CF 2 CF 2 CF 2 H、 -CH 2 CF 2 CF 2 CFH 2 、 -CH 2 CH 2 CF 2 CF 3 、 -CH 2 CH 2 CF 2 CF 2 H、 -CH 2 CH 2 CF 2 CFH 2 、 -CH 2 CH 2 CH 2 CF 3 、 -CH 2 CH 2 CH 2 CF 2 H、 -CH 2 CH 2 CH 2 CFH 2 、 -CF(CF 3 )CF 2 CF 3 、 -CF(CF 2 H)CF 2 CF 3 、 -CF(CFH 2 )CF 2 CF 3 、 -CF(CF 3 )CF 2 CF 2 H、 -CF(CF 3 )CF 2 CFH 2 、 -CF(CF 3 )CH 2 CF 3 、 -CF(CF 3 )CH 2 CF 2 H、 -CF(CF 3 )CH2 CFH 2 ,-CH(CF 3 )CF 2 CF 3 ,-CH(CF 2 H)CF 2 CF 3 ,-CH(CFH 2 )CF 2 CF 3 ,-CH(CF 3 )CF 2 CF 2 H,-CH(CF 3 )CF 2 CFH 2 ,-CH(CF 3 )CH 2 CF 3 ,-CH(CF 3 )CH 2 CF 2 H,-CH(CF 3 )CH 2 CFH 2 ,-CF 2 CF(CF 3 )CF 3 ,-CF 2 CF(CF 2 H)CF 3 ,-CF 2 CF(CFH 2 )CF 3 ,-CF 2 CF(CF 3 )CF 2 H,-CF 2 CF(CF 3 )CFH 2 ,-CH 2 CF(CF 3 )CF 3 ,-CH 2 CF(CF 2 H)CF 3 ,-CH 2 CF(CFH 2 )CF 3 ,-CH 2 CF(CF 3 )CF 2 H,-CH 2 CF(CF 3 )CFH 2 ,-CH 2 CH(CF 3 )CF3 , -CH 2 CH(CF 2 H)CF 3 , -CH 2 CH(CFH 2 )CF 3 , -CH 2 CH(CF 3 )CF 2 H, -CH 2 CH(CF 3 )CFH 2 , -CF 2 CH(CF 3 )CF 3 , -CF 2 CH(CF 2 H)CF 3 , -CF 2 CH(CFH 2 )CF 3 , -CF 2 CH(CF 3 )CF 2 H, -CF 2 CH(CF 3 )CFH 2 , -C(CF 3 ) 3 , -C(CF 2 H) 3 , -C(CFH 2 ) 3 Examples of such fluorinated alkyl groups include -CF 3 , -CF 2 H, -CF 2 CF 3 , -CH 2 CF 3 , -CH 2 CF 2 , -CH 2 CFH 2 , -CH 2 CH 2 CF 3 , -CH 2 CF 2 CF 3 , -CH 2 CF 2 CF 2 H, -CH 2 CF 2 CFH 2 These are particularly preferred because of their good compatibility with other solvents, viscosity, and oxidation resistance.

[0202] Specific examples of the above fluorinated chain carboxylic acid esters include, for example, CF 3 CH 2 C(=O)OCH 3 (methyl 3,3,3-trifluoropropionate), HCF 2 C(=O)OCH 3 (methyl difluoroacetate), HCF 2 C(=O)OC 2 H 5 (ethyl difluoroacetate), CF 3 C(=O)OCH 2 CH 2 CF 3 、CF 3 C(=O)OCH 2 C 2 F 5 、CF 3 C(=O)OCH 2 CF 2 CF 2 H (2,2,3,3-tetrafluoropropyl trifluoroacetate), CF 3 C(=O)OCH 2 CF 3 、CF 3 C(=O)OCH(CF 3 ) 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, CH 3 C(=O)OCH 2 CF 3(2,2,2-Trifluoroethyl) acetate, 1H,1H-heptafluorobutyl acetate, methyl 4,4,4-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, methyl heptafluorobutyrate, etc. can be exemplified by one or more of them. Among them, CF 3 CH 2 C(=O)OCH 3 、HCF 2 C(=O)OCH 3 、HCF 2 C(=O)OC 2 H 5 、CF 3 C(=O)OCH 2 C 2 F 5 、CF 3 C(=O)OCH 2 CF 2 CF 2 H、CF 3 C(=O)OCH 2 CF 3 、CF 3 C(=O)OCH(CF 3 ) 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, CH 3 C(=O)OCH 2 CF 3, 1H,1H - heptafluorobutyl acetate, methyl 4,4,4 - 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, methyl heptafluorobutyrate are preferred because of their good compatibility with other solvents and rate characteristics, CF 3 CH 2 C(=O)OCH 3 , HCF 2 C(=O)OCH 3 , HCF 2 C(=O)OC 2 H 5 , CH 3 C(=O)OCH 2 CF 3 are more preferred, and HCF 2 C(=O)OCH 3 , HCF 2 C(=O)OC 2 H 5 , CH 3 C(=O)OCH 2 CF 3 are particularly preferred.

[0203] The above fluorinated chain carboxylic acid esters may be used alone or in combination of two or more in any combination and ratio.

[0204] When the above fluorinated chain carboxylic acid ester is included, the content of the above fluorinated chain carboxylic acid ester is preferably 10 - 90% by volume, more preferably 40 - 85% by volume, and still more preferably 50 - 80% by volume based on the above solvent.

[0205] The above solvent preferably contains at least one selected from the group consisting of the above cyclic carbonate, the above linear carbonate, and the above linear carboxylic acid ester, and more preferably contains the above cyclic carbonate and at least one selected from the group consisting of the above linear carbonate and the above linear carboxylic acid ester. The above cyclic carbonate is preferably a saturated cyclic carbonate. The electrolyte containing the solvent of the above composition can further improve the high-temperature storage characteristics and cycle characteristics of the electrochemical device.

[0206] When the above solvent contains the above cyclic carbonate and at least one selected from the group consisting of the above linear carbonate and the above linear carboxylic acid ester, it is preferably contained in a total of 10 to 100% by volume, more preferably 30 to 100% by volume, and still more preferably 50 to 100% by volume.

[0207] When the above solvent contains the above cyclic carbonate and at least one selected from the group consisting of the above linear carbonate and the above linear carboxylic acid ester, the volume ratio of the above cyclic carbonate to at least one selected from the group consisting of the above linear carbonate and the above linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, still more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, still more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0208] The above solvent preferably also contains at least one selected from the group consisting of the above non-fluorinated saturated cyclic carbonate, the above non-fluorinated chain carbonate, and the above non-fluorinated chain carboxylic acid ester. More preferably, it contains the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated chain carbonate and the above non-fluorinated chain carboxylic acid ester. The electrolytic solution containing the solvent of the above composition can be suitably used for an electrochemical device used at a relatively low voltage.

[0209] When the above solvent contains the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated chain carbonate and the above non-fluorinated chain carboxylic acid ester, it is preferable that the total of the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated chain carbonate and the above non-fluorinated chain carboxylic acid ester is 5 to 100% by volume, more preferably 20 to 100% by volume, and still more preferably 30 to 100% by volume.

[0210] When the above electrolytic solution contains the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated chain carbonate and the above non-fluorinated chain carboxylic acid ester, the volume ratio of the above non-fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the above non-fluorinated chain carbonate and the above non-fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, still more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, still more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0211] The above solvent preferably also contains at least one selected from the group consisting of the above fluorinated saturated cyclic carbonate, the above fluorinated chain carbonate, and the above fluorinated chain carboxylic acid ester, and more preferably contains the above fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above fluorinated chain carbonate and the above fluorinated chain carboxylic acid ester. The electrolyte containing the solvent of the above composition can be suitably used not only for electrochemical devices used at relatively low voltages but also for electrochemical devices used at relatively high voltages.

[0212] When the above solvent contains the above fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above fluorinated chain carbonate and the above fluorinated chain carboxylic acid ester, it is preferable that the total of the above fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above fluorinated chain carbonate and the above fluorinated chain carboxylic acid ester is 5 to 100% by volume, more preferably 10 to 100% by volume, and still more preferably 30 to 100% by volume.

[0213] When the above solvent contains the above fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above fluorinated chain carbonate and the above fluorinated chain carboxylic acid ester, the volume ratio of the above fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the above fluorinated chain carbonate and the above fluorinated chain carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, still more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, still more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0214] In addition, an ionic liquid (excluding compound (1)) can also be used as the above solvent. An "ionic liquid" is a liquid composed of ions formed by combining an organic cation and an anion.

[0215] The organic cation is not particularly limited, and examples thereof include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0216] The anion that serves as the counterion for these organic cations is not particularly limited, and examples thereof include PF 6 anion, PF 3 (C 2 F 5 ) 3 anion, PF 3 (CF 3 ) 3 anion, BF 4 anion, BF 2 (CF 3 ) 2 anion, BF 3 (CF 3 ) anion, bisoxalatoborate anion, P(C 2 O 4 )F 2 anion, Tf (trifluoromethanesulfonyl) anion, Nf (nonafluorobutanesulfonyl) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanoamine anion, and halide anions can be used.

[0217] The above solvent is preferably a non-aqueous solvent, and the electrolyte solution of the present disclosure is preferably a non-aqueous electrolyte solution. The content of the above solvent is preferably 70 to 99.999% by mass in the electrolyte solution, more preferably 80% by mass or more, and more preferably 92% by mass or less.

[0218] The electrolyte solution of the present disclosure may further contain a compound (5) represented by the general formula (5) (however, excluding compound (1)).

[0219] General formula (5): [Chemical formula] (wherein A a+ is a metal ion, a hydrogen ion or an onium ion; a is an integer of 1 to 3, b is an integer of 1 to 3, p is b / a, n203 is an integer of 1 to 4, n201 is an integer of 0 to 8, n202 is 0 or 1, and Z 201 is a transition metal, an element of Group III, Group IV or Group V of the periodic table. X 201 is 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 (the alkylene group, the halogenated alkylene group, the arylene group, and the halogenated arylene group may have a substituent or a heteroatom in its structure, and when n202 is 1 and n203 is 2 to 4, n203 Xs 201 may be bonded to each other). L 201 is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (the alkylene group, the halogenated alkylene group, the arylene group, and the halogenated arylene group may have a substituent or a heteroatom in its structure, and when n201 is 2 to 8, n201 Ls 201 may be bonded to each other to form a ring) or -Z 203 Y 203 . Y 201 Y 202 and Z 203 are each independently O, S, NY 204 , a hydrocarbon group or a fluorinated hydrocarbon group. Y 203 and Y 204 are each independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms or a halogenated aryl group having 6 to 20 carbon atoms (the alkyl group, the halogenated alkyl group, the aryl group and the halogenated aryl group may have a substituent or a heteroatom in its structure, and Y 203 or Y 204When there are a plurality of them, they may combine with each other to form a ring.

[0220] A a+ Examples of A include lithium ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, silver ion, zinc ion, copper ion, cobalt ion, iron ion, nickel ion, manganese ion, titanium ion, lead ion, chromium ion, vanadium ion, ruthenium ion, yttrium ion, lanthanoid ion, actinoid ion, tetrabutylammonium ion, tetraethylammonium ion, tetramethylammonium ion, triethylmethylammonium ion, triethylammonium ion, pyridinium ion, imidazolium ion, hydrogen ion, tetraethylphosphonium ion, tetramethylphosphonium ion, tetraphenylphosphonium ion, triphenylsulfonium ion, triethylsulfonium ion, etc.

[0221] When used for applications such as electrochemical devices, A a+ is preferably lithium ion, sodium ion, magnesium ion, tetraalkylammonium ion, hydrogen ion, and particularly preferably lithium ion. The valence a of the cation of A is an integer of 1 to 3. When it is greater than 3, the crystal lattice energy becomes large, resulting in a problem that it becomes difficult to dissolve in a solvent. Therefore, when solubility is required, 1 is more preferable. Similarly, the valence b of the anion is also an integer of 1 to 3, and particularly 1 is preferable. The constant p representing the ratio of the cation to the anion is necessarily determined by the ratio b / a of their valences. a+ Next, the ligand part of the general formula (5) will be described. In this specification, the organic or inorganic part bonded to Z

[0222] in the general formula (5) is called a ligand. 201 is called a ligand.

[0223] Z 201is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb, more preferably Al, B or P.

[0224] 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 groups and arylene groups may have substituents or heteroatoms in their structures. Specifically, instead of hydrogen on the alkylene group and arylene group, a halogen atom, a linear or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group, an amide group, a hydroxyl group may be used as a substituent, or a structure in which nitrogen, sulfur, or oxygen is introduced instead of carbon on the alkylene and arylene may be used. When n202 is 1 and n203 is 2 to 4, the n203 Xs 201 may be bonded to each other. Examples of such a ligand include ethylenediaminetetraacetic acid.

[0225] L 201 represents a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms or -Z 203 Y 203 (Z 203 , Y 203 will be described later). Here, the alkyl group and aryl group of L are also similar to those of X 201 and may have substituents or heteroatoms in their structures. When n201 is 2 to 8, the n201 Ls 201 may be bonded to each other to form a ring. As L 201 , a fluorine atom or a cyano group is preferable. In the case of a fluorine atom, the solubility and dissociation degree of the salt of the anion compound are improved, and accordingly, the ionic conductivity is improved. In addition, the oxidation resistance is improved, and thus the occurrence of side reactions can be suppressed.

[0226] Y 201 、 Y 202 and Z 203 are each independently O, S, NY 204 , a hydrocarbon group or a fluorinated hydrocarbon group. Y 201 and Y 202 are preferably O, S or NY 204 , more preferably O. As a characteristic of compound (5), Y 201 and Y 202 result in a bond with Z 201 , so that these ligands form a chelate structure with Z 201 . Due to the effect of this chelate, the heat resistance, chemical stability, and hydrolysis resistance of this compound are improved. The constant n202 in this ligand is 0 or 1. In particular, when it is 0, this chelate ring becomes a five-membered ring, so the chelate effect is most strongly exerted and the stability is increased, which is preferable. In addition, in this specification, a fluorinated hydrocarbon group is a group in which at least one hydrogen atom of a hydrocarbon group is substituted with a fluorine atom.

[0227] Y 203 and Y 204 are each independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms or a halogenated aryl group having 6 to 20 carbon atoms. These alkyl groups and aryl groups may have a substituent or a hetero atom in their structure. Also, when there are a plurality of Y 203 or Y 204 , they may each be bonded to form a ring.

[0228] Also, the constant n203 related to the number of the above-described ligands is an integer of 1 to 4, preferably 1 or 2, more preferably 2. Also, the constant n201 related to the number of the above-described ligands is an integer of 0 to 8, preferably an integer of 0 to 4, more preferably 0, 2 or 4. Further, when n203 is 1, n201 is preferably 2, and when n203 is 2, n201 is preferably 0.

[0229] In general formula (5), the alkyl group, halogenated alkyl group, aryl group, and halogenated aryl group include those having branches and other functional groups such as hydroxyl groups and ether bonds.

[0230] Compound (5) has the general formula:

Chemical formula

Chemical formula

[0231] Examples of compound (5) include lithium oxalatoborate salts, such as lithium bis(oxalato)borate (LIBOB) represented by the following formula:

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0232] Examples of the compound (5) also include dicarboxylic acid complex salts in which the complex central 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.

[0233] Examples of the compound (5) also include dicarboxylic acid complex salts in which the complex central 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.

[0234] Examples of the compound (5) also include dicarboxylic acid complex salts in which the complex central element is aluminum, such as LiAl(C 2 O 4 ) 2 , LiAlF 2 (C 2 O 4 ).

[0235] Among them, 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 because they can contribute to the ease of acquisition and the formation of a stable film-like structure. As the compound (5), lithium bis(oxalato)borate is particularly preferred.

[0236] Regarding the content of the compound (5), since more excellent cycle characteristics can be obtained, it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, preferably 10% by mass or less, and more preferably 3% by mass or less with respect to the above solvent.

[0237] The electrolyte solution of the present disclosure preferably further contains an electrolyte salt (excluding the compounds (1) and (5)). As the above electrolyte salt, any one that can be used in an electrolyte solution can be used, such as a lithium salt, an ammonium salt, a metal salt, a liquid salt (ionic liquid), an inorganic polymer type salt, an organic polymer type salt, etc.

[0238] As the electrolyte salt of the electrolyte solution for a lithium ion secondary battery, a lithium salt is preferred. Any one of the above lithium salts can be used, and specifically, the following can be mentioned. For example, LiPF 6 , LiBF 4 , LiClO 4 , LiAlF 4 , LiSbF 6 , LiTaF 6 , LiWF 7 , LiAsF 6 , LiAlCl 4 , LiI, LiBr, LiCl, LiB 10 Cl 10 , Li 2 SiF 6 , Li 2 PFO 3 , LiPO 2 F 2 and other inorganic lithium salts; LiWOF 5 and other lithium tungstate salts; HCO 2 Li, CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CF 2 CO 2 Lithium carboxylates such as Li; FSO 3 Li, CH 3 SO 3 Li, CH 2 FSO 3 Li, CHF 2 SO 3 Li, CF 3 SO 3 Li, CF 3 CF 2 SO 3 Li, CF 3 CF 2 CF 2 SO 3 Li, CF 3 CF 2 CF 2 CF 2 SO 3 Li, lithium methyl sulfate, lithium ethyl sulfate (C 2 H 5 OSO 3 Li), lithium salts having an S=O group such as lithium 2,2,2-trifluoroethyl sulfate; LiN(FCO) 2 , LiN(FCO)(FSO 2 ), LiN(FSO 2 ) 2 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 )2 , lithium bis(perfluoroethanesulfonyl)imide, lithium cyclic 1,2-perfluoroethanedisulfonyl imide, lithium cyclic 1,3-perfluoropropanedisulfonyl imide, lithium cyclic 1,2-ethanedisulfonyl imide, lithium cyclic 1,3-propanedisulfonyl imide, lithium cyclic 1,4-perfluorobutanedisulfonyl imide, LiN(CF 3 SO 2 )(FSO 2 ), LiN(CF 3 SO 2 )(C 3 F 7 SO 2 ), LiN(CF 3 SO 2 )(C 4 F 9 SO 2 ), LiN(POF 2 ) 2 and other lithium imide salts; LiC(FSO 2 ) 3 , LiC(CF 3 SO 2 ), 3 , LiC(C 2 F 5 SO 2 ) 3 and other lithium methide salts; In addition, salts represented by the formula: LiPF a (C n F 2n+1 )(where a is an integer from 0 to 5 and n is an integer from 1 to 6) (for example, LiPF 6-a (C 3 (C 2 F 5 ) 3 , LiPF 3 (CF 3 ) 3 , LiPF 3 (iso-C 3 F 7 ) 3 , LiPF 5 (iso-C 3 F 7 ), LiPF 4 (CF 3 ) 2 , LiPF4 (C 2 F 5 ) 2 )、LiPF 4 (CF 3 SO 2 ) 2 、LiPF 4 (C 2 F 5 SO 2 ) 2 、LiBF 3 CF 3 、LiBF 3 C 2 F 5 、LiBF 3 C 3 F 7 、LiBF 2 (CF 3 ) 2 、LiBF 2 (C 2 F 5 ) 2 、LiBF 2 (CF 3 SO 2 ) 2 、LiBF 2 (C 2 F 5 SO 2 ) 2 and other fluorine-containing organic lithium salts such as LiSCN, LiB(CN) 4 、LiB(C 6 H 5 ) 4 、Li 2 (C 2 O 4 )、LiP(C 2 O 4 ) 3 、Li 2 B 12 F b H 12-b (b is an integer from 0 to 3), etc.

[0239] Among them, LiPF 6 、LiBF 4 、LiSbF 6 、LiTaF 6 、LiPO 2 F 2 、FSO 3 Li、CF3 SO 3 Li, LiN(FSO 2 ) 2 、LiN(FSO 2 )(CF 3 SO 2 )、LiN(CF 3 SO 2 ) 2 、LiN(C 2 F 5 SO 2 ) 2 、 lithium cyclic 1,2 - perfluoroethanedisulfonylimide, lithium cyclic 1,3 - perfluoropropanedisulfonylimide, LiC(FSO 2 ) 3 、LiC(CF 3 SO 2 ) 3 、LiC(C 2 F 5 SO 2 ) 3 、LiBF 3 CF 3 、LiBF 3 C 2 F 5 、LiPF 3 (CF 3 ) 3 、LiPF 3 (C 2 F 5 ) 3 etc. are particularly preferred in that they have the effect of improving output characteristics, high - rate charge - discharge characteristics, high - temperature storage characteristics, cycle characteristics, etc. LiPF 6 、LiN(FSO 2 ) 2 and LiBF 4 and at least one lithium salt selected from the group consisting of them are most preferred.

[0240] These electrolyte salts may be used alone or in combination of two or more. A preferred example of using two or more in combination is the combination of LiPF 6 and LiBF 4 , or the combination of LiPF 6 and LiPO 2 F 2 、C 2 H 5 OSO 3Li or FSO 3 It is used in combination with Li and has the effect of improving high-temperature storage characteristics, load characteristics, and cycle characteristics.

[0241] In this case, for 100% by mass of the entire electrolyte, LiBF 4 , LiPO 2 F 2 , C 2 H 5 OSO 3 Li or FSO 3 There is no limit to the blending amount of Li, and it is arbitrary as long as the effects of the present disclosure are not significantly impaired. However, for the electrolyte of the present disclosure, it 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 still more preferably 5% by mass or less.

[0242] Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of these two has the effect of suppressing deterioration due to high-temperature storage. Examples of the organic lithium salt include CF 3 SO 3 Li, LiN(FSO 2 ) 2 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO 2 ) 3 , LiC(CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 , C 2 F 5, LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3 etc. are preferable. In this case, the ratio of the organic lithium salt to 100% by mass of the entire electrolytic solution is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and is preferably 30% by mass or less, particularly preferably 20% by mass or less.

[0243] The concentration of these electrolyte salts in the electrolytic solution is not particularly limited as long as the effects of the present disclosure are not impaired. From the viewpoint of keeping the electric conductivity of the electrolytic solution in a good range and ensuring good battery performance, the total molar concentration of lithium in the electrolytic solution is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more, and is preferably 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less.

[0244] If the total molar concentration of lithium is too low, the electric conductivity of the electrolytic solution may be insufficient. On the other hand, if the concentration is too high, the electric conductivity may decrease due to an increase in viscosity, and the battery performance may decrease.

[0245] As the electrolyte salt of the electrolytic solution for the electric double layer capacitor, an ammonium salt is preferable. Examples of the above ammonium salt include the following (IIa) to (IIe). (IIa) Tetraalkyl quaternary ammonium salt General formula (IIa):

[0246] [Chemical formula] (In the formula, R 1a , R 2a , R 3a and R 4a are the same or different and are each an alkyl group which may contain an ether bond having 1 to 6 carbon atoms; X - is an anion) The tetraalkyl quaternary ammonium salts represented by the following can be preferably exemplified. Further, those in which some or all of the hydrogen atoms of this ammonium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferable from the viewpoint of improving oxidation resistance.

[0247] Specific examples include the general formula (IIa-1):

[0248]

Chemical formula

[0249]

Chemical formula

[0250] The anion X - may be an inorganic anion or an organic anion. Examples of the inorganic anion include AlCl 4 - , BF 4 - , PF 6 - , AsF 6 - , TaF 6 - , I - , SbF 6 -include. Examples of the organic anion include, for example, bisoxalatoborate anion, difluorooxalatoborate anion, tetrafluorooxalatophosphate anion, difluorobisoxalatophosphate anion, CF 3 COO - 、CF 3 SO 3 - 、(CF 3 SO 2 ) 2 N - 、(C 2 F 5 SO 2 ) 2 N - etc.

[0251] Among these, BF 4 - 、PF 6 - 、AsF 6 - 、SbF 6 - are preferred.

[0252] Suitable specific examples of the tetraalkyl quaternary ammonium salt include Et 4 NBF 4 、Et 4 NClO 4 、Et 4 NPF 6 、Et 4 NAsF 6 、Et 4 NSbF 6 、Et 4 NCF 3 SO 3 、Et 4 N(CF 3 SO 2 ) 2 N、Et 4 NC 4 F 9 SO 3 、Et 3 MeNBF 4 、Et 3 MeNClO 4 、Et 3 MeNPF6 , Et 3 MeNAsF 6 , Et 3 MeNSbF 6 , Et 3 MeNCF 3 SO 3 , Et 3 MeN(CF 3 SO 2 ) 2 N, Et 3 MeNC 4 F 9 SO 3 may be used, particularly, Et 4 NBF 4 , Et 4 NPF 6 , Et 4 NSbF 6 , Et 4 NAsF 6 , Et 3 MeNBF 4 , examples include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium salts, etc.

[0253] (IIb) Spirocyclic bipyrrolidinium salts General formula (IIb-1):

[0254] [Chemical formula] (In the formula, R 8a and R 9a are the same or different, and each is an alkyl group having 1 to 4 carbon atoms; X - is an anion; n1 is an integer from 0 to 5; n2 is an integer from 0 to 5) Spirocyclic bipyrrolidinium salts represented by, general formula (IIb-2):

[0255] [Chemical formula] (In the formula, R 10a and R 11a are the same or different, and each is an alkyl group having 1 to 4 carbon atoms; X - is an anion; n3 is an integer from 0 to 5; n4 is an integer from 0 to 5) The spirobipyrrolidinium salt represented by the formula, or the general formula (IIb-3):

[0256] [Chemical formula] (In the formula, R 12a and R 13a are the same or different and are each an alkyl group having 1 to 4 carbon atoms; X - is an anion; n5 is an integer of 0 to 5; n6 is an integer of 0 to 5) The spirobipyrrolidinium salt represented by the formula is preferably mentioned. Further, those in which some or all of the hydrogen atoms of this spirobipyrrolidinium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferable from the viewpoint of improving oxidation resistance.

[0257] Preferred specific examples of the anion X - are the same as those in the case of (IIa). Among them, BF 4 -, PF 6 -, (CF 3 SO 2 ) 2 N- or (C 2 F 5 SO 2 ) 2 N- are preferred from the viewpoint of high dissociation property and low internal resistance under high voltage.

[0258] Preferred specific examples of the spirobipyrrolidinium salt include, for example, [Chemical formula] and the like.

[0259] This spirobipyrrolidinium salt is excellent in solubility in solvents, oxidation resistance, and ionic conductivity.

[0260] (IIc) Imidazolium salt General formula (IIc):

[0261] [Chemical formula] (wherein R 14a and R 15a are the same or different and each is an alkyl group having 1 to 6 carbon atoms; X - is an anion) Preferred examples of the imidazolium salt represented by the formula can be exemplified. Further, those in which some or all of the hydrogen atoms of the imidazolium salt are substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferable from the viewpoint of improving oxidation resistance.

[0262] The preferred specific examples of the anion X - are the same as those of (IIa).

[0263] Preferred specific examples include, for example

[0264]

Chemical formula

[0265] This imidazolium salt is excellent in that it has low viscosity and good solubility.

[0266] (IId): N-alkylpyridinium salt General formula (IId):

[0267]

Chemical formula

[0268] The preferred specific examples of the anion X - are the same as those of (IIa).

[0269] Preferred specific examples include, for example

[0270]

Chemical formula

[0271] This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

[0272] (IIe) N,N-dialkylpyrrolidinium salt General formula (IIe):

[0273]

Chemical formula

[0274] Preferred specific examples of the anion X - are the same as those in (IIa).

[0275] Preferred specific examples include, for example

[0276]

Chemical formula

[0277]

Chemical formula

[0278] This N,N-dialkylpyrrolidinium salt is excellent in that it has low viscosity and good solubility.

[0279] Among these ammonium salts, (IIa), (IIb) and (IIc) are preferable in terms of good solubility, oxidation resistance and ion conductivity. Further,

[0280] [Chemical formula] (In the formula, Me is a methyl group; Et is an ethyl group; X - , x, and y are the same as those in formula (IIa-1)) is preferable.

[0281] Also, a lithium salt may be used as the electrolyte salt for the electric double layer capacitor. Examples of the lithium salt include LiPF 6 , LiBF 4 , LiN(FSO 2 ) 2 , LiAsF 6 , LiSbF 6 , LiN(SO 2 C 2 H 5 ) 2 is preferable. Furthermore, a magnesium salt may be used to further improve the capacitance. Examples of the magnesium salt include Mg(ClO 4 ) 2 , Mg(OOC 2 H 5 ) 2 etc. are preferable.

[0282] When the electrolyte salt is the above ammonium salt, the concentration is preferably 0.7 mol / liter or more. If it is less than 0.7 mol / liter, not only the low temperature characteristics deteriorate, but also the initial internal resistance may increase. The concentration of the above electrolyte salt is more preferably 0.9 mol / liter or more. In terms of low temperature characteristics, the upper limit of the above concentration is preferably 2.0 mol / liter or less, and more preferably 1.5 mol / liter or less. When the above ammonium salt is triethylmethylammonium tetrafluoroborate (TEMABF 4In the case of , the concentration is preferably 0.7 to 1.5 mol / L in terms of excellent low-temperature characteristics. In the case of spirobipyrrolidinium tetrafluoroborate (SBPBF 4 ), it is preferably 0.7 to 2.0 mol / L.

[0283] The electrolyte of the present disclosure has the general formula (2):

Chemical formula

[0284] When n21 is 2 or 3, two or three X 21 may be the same or different. Y 21 and Z 21 When there are a plurality of Y 21 and Z 21 present, the plurality of Y

[0285] X 21 As, -CY 21 Z 21 -(where Y 21 and Z 21 are as described above) or -CY 21 =CZ 21 -(where Y 21 and Z 21 are as described above) is preferred.

[0286] Y 21 As, H-, F-, CH 3 -, CH3 CH 2 -, CH 3 CH 2 CH 2 -, CF 3 -, CF 3 CF 2 -, CH 2 FCH 2 - and CF 3 CF 2 CF 2 At least one selected from the group consisting of - is preferred. Z 21 As, H -, F -, CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, CF 3 -, CF 3 CF 2 -, CH 2 FCH 2 - and CF 3 CF 2 CF 2 At least one selected from the group consisting of - is preferred.

[0287] Or, Y 21 And Z 21 May be bonded to each other to form a carbocyclic or heterocyclic ring which may contain an unsaturated bond and may have aromaticity. The number of carbon atoms in the ring is preferably 3 to 20.

[0288] Next, specific examples of the compound (2) will be described. In the following examples, the "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure within the scope not contrary to the spirit of the present disclosure. For example, dimers, trimers, and tetramers composed of a plurality of acid anhydrides, or those having structural isomerism such as having the same number of carbon atoms in the substituent but having a branched chain, or those having different bonding sites of the substituent to the acid anhydride, etc. can be mentioned.

[0289] Specific examples of the acid anhydride forming a 5-membered ring structure include succinic anhydride, methylsuccinic anhydride (4-methylsuccinic anhydride), dimethylsuccinic anhydride (4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride, etc.), 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5-divinylsuccinic anhydride, phenylsuccinic anhydride (4-phenylsuccinic anhydride), 4,5-diphenylsuccinic anhydride, 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, etc., and their analogs, etc.

[0290] Specific examples of the acid anhydride forming a 6-membered ring structure include cyclohexanedicarboxylic anhydride (such as cyclohexane-1,2-dicarboxylic anhydride), 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride, glutaconic anhydride, 2-phenylglutaric anhydride, etc., and their analogs, etc.

[0291] Specific examples of the acid anhydride forming other cyclic structures include 5-norbornene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, diglycolic anhydride, etc., and their analogs, etc.

[0292] While forming a cyclic structure, specific examples of the acid anhydride substituted with a halogen atom include monofluoro succinic anhydride (such as 4-fluoro succinic anhydride), 4,4-difluoro succinic anhydride, 4,5-difluoro succinic anhydride, 4,4,5-trifluoro succinic anhydride, trifluoromethyl succinic anhydride, tetrafluoro succinic anhydride (4,4,5,5-tetrafluoro succinic anhydride), 4-fluoro maleic anhydride, 4,5-difluoro maleic anhydride, trifluoromethyl maleic anhydride, 5-fluoro itaconic anhydride, 5,5-difluoro itaconic anhydride, and the like, and their analogs.

[0293] As the compound (2), among others, 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, phenyl succinic anhydride, 2-phenyl glutaric anhydride, maleic anhydride, methyl maleic anhydride, trifluoromethyl maleic anhydride, phenyl maleic anhydride, succinic anhydride, methyl succinic anhydride, dimethyl succinic anhydride, trifluoromethyl succinic anhydride, monofluoro succinic anhydride, tetrafluoro succinic anhydride, etc. are preferable, maleic anhydride, methyl maleic anhydride, trifluoromethyl maleic anhydride, succinic anhydride, methyl succinic anhydride, trifluoromethyl succinic anhydride, tetrafluoro succinic anhydride are more preferable, and maleic anhydride, succinic anhydride are even more preferable.

[0294] The compound (2) is represented by the general formula (3):

[0295]

Chemical formula

[0296] [Chem.] (wherein X 41 and X 42 are the same or different and are each at least one selected from the group consisting of compounds (4) represented by a group containing at least H, C, O, or F).

[0297] X 31 ~X 34 are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group, and a fluorinated alkenyl group, which are the same or different. The carbon number of X 31 ~X 34 is preferably from 1 to 10, more preferably from 1 to 3.

[0298] X 31 ~X 34 are preferably at least one selected from the group consisting of H-, F-, CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, CF 3 -, CF 3 CF 2 -, CH 2 FCH 2 -, and CF 3 CF 2 CF 2 -, and is more preferably at least one selected from the group consisting of these.

[0299] X 41 and X 42 are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group, and a fluorinated alkenyl group, which are the same or different. The carbon number of X 41 and X 42 is preferably from 1 to 10, more preferably from 1 to 3.

[0300] X 41 and X 42which may be the same or different and are H-, F-, CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, CF 3 -, CF 3 CF 2 -, CH 2 FCH 2 - and CF 3 CF 2 CF 2 At least one selected from the group consisting of - is more preferable.

[0301] Compound (3) is preferably any of the following compounds.

[0302]

Chemical formula

[0303] Compound (4) is preferably any of the following compounds.

[0304]

Chemical formula

[0305] When the above electrolyte solution is stored at a high temperature, the capacity retention rate is less likely to decrease further, and the amount of gas generated is less likely to increase further. Therefore, it is preferable that the above electrolyte solution contains 0.0001 to 15% by mass of compound (2). As the content of compound (2), 0.01 to 10% by mass is more preferable, 0.1 to 3% by mass is still more preferable, and 0.1 to 1.0% by mass is particularly preferable.

[0306] When the above electrolyte contains both compounds (3) and (4), even when stored at high temperatures, the capacity retention rate is less likely to further decrease, and the amount of gas generated is less likely to further increase. 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) with respect 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).

[0307] The electrolyte of the present disclosure may contain at least one selected from the group consisting of nitrile compounds represented by the following general formulas (1a), (1b), and (1c).

Chemical formula

Chemical formula

Chemical formula

[0308] In the above general formula (1a), R a and R b Each independently is a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least a part of the hydrogen atoms of the alkyl group is substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among them, a fluorine atom is preferable. As the alkyl group, those having 1 to 5 carbon atoms are preferable. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and the like. Examples of the group in which at least a part of the hydrogen atoms of the alkyl group is substituted with a halogen atom include a group in which at least a part of the hydrogen atoms of the above-mentioned alkyl group is substituted with the above-mentioned halogen atom. R a and R b When is an alkyl group or a group in which at least a part of the hydrogen atoms of the alkyl group is substituted with a halogen atom, R a and R b May be bonded to each other to form a ring structure (for example, a cyclohexane ring). R a and R b Is preferably a hydrogen atom or an alkyl group.

[0309] In the above general formula (1a), n is an integer from 1 to 10. When n is 2 or more, the n R a 's may all be the same or at least some of them may be different. The same applies to R b . n is preferably an integer from 1 to 7, more preferably an integer from 2 to 5.

[0310] As the nitrile compound represented by the above general formula (1a), dinitrile and tricarbonitrile are preferred. Specific examples of dinitriles include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, 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-dimethylsuccinonitrile, 2,2-diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 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. Among these, succinonitrile, glutaronitrile, and adiponitrile are particularly preferred. Specific examples of tricarbonitrile include pentane tricarbonitrile, propane tricarbonitrile, 1,3,5 - hexane tricarbonitrile, 1,3,6 - hexane tricarbonitrile, heptane tricarbonitrile, 1,2,3 - propane tricarbonitrile, 1,3,5 - pentane tricarbonitrile, cyclohexane tricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, tris(2 - cyanoethyl)amine, etc. Particularly preferred are 1,3,6 - hexane tricarbonitrile and cyclohexane tricarbonitrile, and most preferred is cyclohexane tricarbonitrile.

[0311] In the general formula (1b), R c is a hydrogen atom, a halogen atom, an alkyl group, a group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms, or a group represented by NC - R c1 -X c1 -(R c1 is an alkylene group, X c1 represents an oxygen atom or a sulfur atom.). R d and R e are each independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms. Examples of the halogen atom, alkyl group, and the group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms are the same as those exemplified for the general formula (1a). In the above NC - R c1 -X c1 -, R c1 is an alkylene group. As the alkylene group, an alkylene group having 1 to 3 carbon atoms is preferred. R c , R d and R e are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms. R c , R d and R eAt least one of them is preferably a halogen atom or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted with a halogen atom, more preferably a fluorine atom or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted with a fluorine atom. R d and R e When is an alkyl group or a group in which at least a part of the hydrogen atoms of an alkyl group is substituted with a halogen atom, R d and R e may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0312] In the above general formula (1b), m is an integer from 1 to 10. When m is 2 or more, the m R d may all be the same or at least a part of them may be different. The same applies to R e . m is preferably an integer from 2 to 7, more preferably an integer from 2 to 5.

[0313] Examples of the nitrile compound represented by the above general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 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. Among these, 3,3,3-trifluoropropionitrile is particularly preferred.

[0314] In the above general formula (1c), Rf , R g , R h and R i is, independently of one another, 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 the alkyl group are substituted with halogen atoms. Examples of the halogen atom, alkyl group, and group in which at least some of the hydrogen atoms of the alkyl group are substituted with halogen atoms include those exemplified for the general formula (1a). Examples of the group containing a cyano group include, in addition to the cyano group, a group in which at least some of the hydrogen atoms of the alkyl group are substituted with a cyano group. Examples of the alkyl group in this case include those exemplified for the general formula (1a). R f , R g , R h and R i at least one of which is a group containing a cyano group. Preferably, R f , R g , R h and R i at least two of which are groups containing a cyano group, and more preferably, R h and R i are groups containing a cyano group. When R h and R i are groups containing a cyano group, R f and R g are preferably hydrogen atoms.

[0315] In the general formula (1c), l is an integer from 1 to 3. When l is 2 or more, all l R f may be the same or at least some may be different. The same applies to R g . l is preferably an integer from 1 to 2.

[0316] Examples of the nitrile compound represented by the general formula (1c) include 3-hexenedinitrile, mucononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, 2-hexenenitrile, etc. Among them, 3-hexenedinitrile and mucononitrile are preferred, and 3-hexenedinitrile is particularly preferred.

[0317] The content of the nitrile compound is preferably 0.2 to 7% by mass based on the electrolytic solution. Thereby, the high-temperature storage characteristics and safety at high voltages of the electrochemical device can be further improved. The lower limit of the total content of the nitrile compound is more preferably 0.3% by mass, still more preferably 0.5% by mass. The upper limit is more preferably 5% by mass, still more preferably 2% by mass, and particularly preferably 0.5% by mass.

[0318] The electrolytic solution of the present disclosure may contain a compound having an isocyanato group (hereinafter, may be abbreviated as "isocyanate"). The isocyanate is not particularly limited, and any isocyanate can be used. Examples of the isocyanate include monoisocyanates, diisocyanates, triisocyanates, and the like.

[0319] Specific examples of the 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, ethyl isocyanate and the like.

[0320] Specific examples of the diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 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)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, bicyclo[2.2.1]heptane-2,5-diylbis(methyl isocyanate), bicyclo[2.2.1]heptane-2,6-diylbis(methyl isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, and the like.

[0321] Specific examples of the triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohex-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4-(isocyanatomethyl)octamethylene diisocyanate, and the like.

[0322] Among them, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohex-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 industrially easily available, and are preferable in that the manufacturing cost of the electrolytic solution can be kept low, and also contribute to the formation of a stable film-like structure from a technical point of view, and are more preferably used.

[0323] The content of the isocyanate is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. However, for the electrolytic solution, it is preferably 0.001% by mass or more and 1.0% by mass or less. When the content of the isocyanate is at least this lower limit, a sufficient cycle characteristic improvement effect can be brought to the non-aqueous electrolytic solution secondary battery. Also, when it is at most this upper limit, an increase in the initial resistance of the non-aqueous electrolytic solution secondary battery can be avoided. The content of the isocyanate is more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and also more preferably 0.8% by mass or less, still more preferably 0.7% by mass or less, particularly preferably 0.6% by mass or less.

[0324] The electrolyte of the present disclosure may contain a cyclic sulfonic acid ester. The cyclic sulfonic acid ester is not particularly limited, and any cyclic sulfonic acid ester can be used. Examples of the cyclic sulfonic acid ester include saturated cyclic sulfonic acid esters, unsaturated cyclic sulfonic acid esters, saturated cyclic disulfonic acid esters, unsaturated cyclic disulfonic acid esters, and the like.

[0325] Specific examples of the saturated cyclic sulfonic acid ester include 1,3 - propane sultone, 1 - fluoro - 1,3 - propane sultone, 2 - fluoro - 1,3 - propane sultone, 3 - fluoro - 1,3 - propane sultone, 1 - methyl - 1,3 - propane sultone, 2 - methyl - 1,3 - propane sultone, 3 - methyl - 1,3 - propane sultone, 1,3 - butane sultone, 1,4 - butane sultone, 1 - fluoro - 1,4 - butane sultone, 2 - fluoro - 1,4 - butane sultone, 3 - fluoro - 1,4 - butane sultone, 4 - fluoro - 1,4 - butane sultone, 1 - methyl - 1,4 - butane sultone, 2 - methyl - 1,4 - butane sultone, 3 - methyl - 1,4 - butane sultone, 4 - methyl - 1,4 - butane sultone, 2,4 - butane sultone, and the like.

[0326] Specific examples of the unsaturated cyclic sulfonic acid ester 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, 2 - methyl - 1 - propene - 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 - propenesultone, 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 - 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, 4 - methyl - 3 - butene - 1,4 - sultone, etc.

[0327] Among them, 1,3 - propane sultone, 1 - fluoro - 1,3 - propane sultone, 2 - fluoro - 1,3 - propane sultone, 3 - fluoro - 1,3 - propane sultone, and 1 - propene - 1,3 - sultone are more preferably used because they can contribute to the ease of acquisition and the formation of a stable film - like structure. The content of the cyclic sulfonic acid ester is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. However, with respect to the electrolytic solution, it is preferably 0.001% by mass or more and 3.0% by mass or less.

[0328] When the content of the cyclic sulfonic acid ester is at least this lower limit, a sufficient cycle characteristic improvement effect can be brought to the non - aqueous electrolytic solution secondary battery. Also, when it is at most this upper limit, an increase in the manufacturing cost of the non - aqueous electrolytic solution secondary battery can be avoided. The content of the cyclic sulfonic acid ester is more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and also more preferably 2.5% by mass or less, still more preferably 2.0% by mass or less, and particularly preferably 1.8% by mass or less.

[0329] The electrolytic solution of the present disclosure may further contain polyethylene oxide having a weight - average molecular weight of 2000 to 4000 and having - OH, - OCOOH, or - COOH at the terminal. By containing such a compound, the stability of the electrode interface can be improved, and the characteristics of the electrochemical device can be improved. Examples of the above - mentioned polyethylene oxide include polyethylene oxide mono - ol, polyethylene oxide carboxylic acid, polyethylene oxide di - ol, polyethylene oxide di - carboxylic acid, polyethylene oxide tri - ol, polyethylene oxide tri - carboxylic acid, etc. These may be used alone or in combination of two or more. Among them, a mixture of polyethylene oxide mono - ol and polyethylene oxide di - ol, and a mixture of polyethylene carboxylic acid and polyethylene di - carboxylic acid are preferably used in that the characteristics of the electrochemical device become better.

[0330] If the weight-average molecular weight of the above polyethylene oxide is too small, there is a risk of being easily oxidized and decomposed. The weight-average molecular weight is more preferably 3000 to 4000. The weight-average molecular weight can be measured by polystyrene conversion using gel permeation chromatography (GPC).

[0331] The content of the above polyethylene oxide is 1×10 -6 ~1×10 -2 mol / kg in the electrolyte is preferable. If the content of the above polyethylene oxide is too large, there is a risk of impairing the characteristics of the electrochemical device. The content of the above polyethylene oxide is more preferably 5×10 -6 mol / kg or more.

[0332] The electrolyte of the present disclosure may further contain, as additives, fluorinated saturated cyclic carbonates, unsaturated cyclic carbonates, overcharge preventives, and other known auxiliaries, etc. Thereby, a decrease in the characteristics of the electrochemical device can be suppressed.

[0333] Examples of the fluorinated saturated cyclic carbonate include the compounds represented by the general formula (A) described above. Among them, fluoroethylene carbonate, difluoroethylene carbonate, monofluoromethyl ethylene carbonate, trifluoromethyl ethylene carbonate, 2,2,3,3,3-pentafluoropropyl ethylene carbonate (4-(2,2,3,3,3-pentafluoro-propyl)-[1.3]dioxolan-2-one) are preferable. The fluorinated saturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.

[0334] The content of the above fluorinated saturated cyclic carbonate is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0.1 to 3% by mass with respect to the above electrolyte.

[0335] Examples of the unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with substituents having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates and the like.

[0336] Examples of the 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, ethynyl ethylene carbonate, propargyl ethylene carbonate, methyl vinylene carbonate, dimethyl vinylene carbonate and the like.

[0337] Specific examples of ethylene carbonates substituted with substituents having an aromatic ring, a carbon-carbon double bond, or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene carbonate, phenyl ethylene carbonate, 4,5-diphenyl ethylene carbonate, 4-phenyl-5-vinyl ethylene carbonate, 4-allyl-5-phenyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, 4-methyl-5-allyl ethylene carbonate, and the like.

[0338] Among them, as the unsaturated cyclic carbonate, 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-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate are preferred. Further, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are particularly preferred because they form a more stable interfacial protective film, and vinylene carbonate is most preferred.

[0339] The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. The molecular weight is preferably 50 or more and 250 or less. Within this range, it is easy to ensure the solubility of the unsaturated cyclic carbonate in the electrolytic solution, and the effects of the present disclosure are likely to be fully exhibited. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or more and even more preferably 150 or less.

[0340] The method for producing the unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production.

[0341] The unsaturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio.

[0342] The content of the above-mentioned unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. The content of the above-mentioned 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 in 100% by mass of the electrolytic solution. Also, the above 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, the electrochemical device using the electrolytic solution is likely to exhibit a sufficient effect of improving cycle characteristics, and it is easy to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation amount, and a decrease in discharge capacity retention rate.

[0343] As the unsaturated cyclic carbonate, in addition to the non-fluorinated unsaturated cyclic carbonate as described above, a fluorinated unsaturated cyclic carbonate can also be preferably used. The fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom. The number of fluorine atoms contained in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. Among them, the number of fluorine atoms is usually 6 or less, preferably 4 or less, and those having 1 or 2 fluorine atoms are most preferred.

[0344] Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond, and the like.

[0345] Examples of the fluorinated vinylene carbonate derivative include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, and the like.

[0346] Examples of the fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-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, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, and the like.

[0347] Among them, as the fluorinated unsaturated cyclic carbonate, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinyl ethylene carbonate, 4-fluoro-4-allyl ethylene carbonate, 4-fluoro-5-vinyl ethylene carbonate, 4-fluoro-5-allyl ethylene carbonate, 4,4-difluoro-4-vinyl ethylene carbonate, 4,4-difluoro-4-allyl ethylene carbonate, 4,5-difluoro-4-vinyl ethylene carbonate, 4,5-difluoro-4-allyl ethylene carbonate, 4-fluoro-4,5-divinyl ethylene carbonate, 4-fluoro-4,5-diallyl ethylene carbonate, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl ethylene carbonate are more preferably used because they form a stable interfacial protective film.

[0348] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and can be arbitrary as long as the effects of the present disclosure are not significantly impaired. The molecular weight is preferably 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 electrolytic solution.

[0349] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and a known method can be arbitrarily selected for production. The molecular weight is more preferably 100 or more and more preferably 200 or less.

[0350] The fluorinated unsaturated cyclic carbonate may be used alone or in combination of two or more in any combination and ratio. Further, the content of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. The content of the fluorinated unsaturated cyclic carbonate is usually preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more in 100% by mass of the electrolytic solution, and preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less. Within this range, the electrochemical device using the electrolytic solution is likely to exhibit a sufficient effect of improving cycle characteristics, and it is easy to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation amount, and a decrease in discharge capacity retention rate.

[0351] The electrolytic solution of the present disclosure may contain a compound having a triple bond. The type is not particularly limited as long as the compound has one or more triple bonds in the molecule. Specific examples of the compound having a triple bond include, for example, the following compounds. Hydrocarbon compounds such as 1-pentyne, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptyne, 2-heptyne, 3-heptyne, 1-octyne, 2-octyne, 3-octyne, 4-octyne, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-dodecyne, 2-dodecyne, 3-dodecyne, 4-dodecyne, 5-dodecyne, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne, 6-phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, dicyclohexylacetylene;

[0352] Monocarbonates such as 2-propynyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynyl phenyl carbonate, 2-propynyl cyclohexyl carbonate, di-2-propynyl carbonate, 1-methyl-2-propynyl methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate, 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate, 3-pentynyl methyl carbonate, 4-pentynyl methyl carbonate; Dicarbonates such as 2-butyne-1,4-diol dimethyl dicarbonate, 2-butyne-1,4-diol diethyl dicarbonate, 2-butyne-1,4-diol dipropyl dicarbonate, 2-butyne-1,4-diol dibutyl dicarbonate, 2-butyne-1,4-diol diphenyl dicarbonate, 2-butyne-1,4-diol dicyclohexyl dicarbonate;

[0353] 2-propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexanecarboxylate, 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 cyclohexanecarboxylate, 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-propynoate, ethyl 2-propynoate, propyl 2-propynoate, vinyl 2-propynoate, 2-propenyl 2-propynoate, 2-butenyl 2-propynoate, 3-butenyl 2-propynoate, methyl 2-butynoate, ethyl 2-butynoate, propyl 2-butynoate, vinyl 2-butynoate, 2-propenyl 2-butynoate, 2-butenyl 2-butynoate, 3-butenyl 2-butynoate, methyl 3-butynoate, ethyl 3-butynoate, propyl 3-butynoate, vinyl 3-butynoate, 2-propenyl 3-butynoate, 2-butenyl 3-butynoate, 3-butenyl 3-butynoate, methyl 2-pentynoate, ethyl 2-pentynoate, propyl 2-pentynoate, vinyl 2-pentynoate, 2-propenyl 2-pentynoate, 2-butenyl 2-pentynoate, 3-butenyl 2-pentynoate, methyl 3-pentynoate, ethyl 3-pentynoate, propyl 3-pentynoate, vinyl 3-pentynoate, 2-propenyl 3-pentynoate, 2-butenyl 3-pentynoate, 3-butenyl 3-pentynoate, methyl 4-pentynoate, ethyl 4-pentynoate, propyl 4-pentynoate, vinyl 4-pentynoate, 2-propenyl 4-pentynoate, 2-butenyl 4-pentynoate, 3-butenyl 4-pentynoate and other monocarboxylic acid esters, fumaric acid esters, methyl pivalate, ethyl pivalate;

[0354] 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 (dicarboxylic acid esters such as 1,2-cyclohexanediol, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolan-4-yl acetate;

[0355] 2-Propynyl oxalate methyl, 2-propynyl oxalate ethyl, 2-propynyl oxalate propyl, 2-propynyl vinyl oxalate, 2-propynyl allyl oxalate, di-2-propynyl oxalate, 2-butynyl methyl oxalate, 2-butynyl ethyl oxalate, 2-butynyl propyl oxalate, 2-butynyl vinyl oxalate, 2-butynyl allyl oxalate, di-2-butynyl oxalate, 3-butynyl methyl oxalate, 3-butynyl ethyl oxalate, 3-butynyl propyl oxalate, 3-butynyl vinyl oxalate, 3-butynyl allyl oxalate, di-3-butynyl oxalate and other oxalic acid diesters;

[0356] 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;

[0357] Phosphonic acid esters such as 2-propynyl methyl(2-propenyl)phosphonate, 2-propynyl 2-butenyl(methyl)phosphonate, 2-propynyl di(2-propenyl)phosphonate, 2-propynyl di(3-butenyl)phosphonate, 1,1-dimethyl-2-propynyl methyl(2-propenyl)phosphonate, 1,1-dimethyl-2-propynyl 2-butenyl(methyl)phosphonate, 1,1-dimethyl-2-propynyl di(2-propenyl)phosphonate, 1,1-dimethyl-2-propynyl di(3-butenyl)phosphonate, 2-propenyl methyl(2-propynyl)phosphonate, 3-butenyl methyl(2-propynyl)phosphonate, 2-propenyl di(2-propynyl)phosphonate, 3-butenyl di(2-propynyl)phosphonate, 2-propenyl 2-propynyl(2-propenyl)phosphonate, and 3-butenyl 2-propynyl(2-propenyl)phosphonate;

[0358] Phosphonic acid esters such as 2-propynyl methyl 2-propenylphosphonate, 2-propynyl methyl(2-butenyl)phosphonate, 2-propynyl (2-propenyl)(2-propenyl)phosphonate, 2-propynyl (3-butenyl)(3-butenyl)phosphonate, (1,1-dimethyl-2-propynyl)(methyl) 2-propenylphosphonate, (1,1-dimethyl-2-propynyl)(methyl) 2-butenylphosphonate, (1,1-dimethyl-2-propynyl)(2-propenyl) 2-propenylphosphonate, and (3-butenyl)(1,1-dimethyl-2-propynyl) 3-butenylphosphonate, (2-propynyl)(2-propenyl) methylphosphonate, (3-butenyl)(2-propynyl) methylphosphonate, (1,1-dimethyl-2-propynyl)(2-propenyl) methylphosphonate, (3-butenyl)(1,1-dimethyl-2-propynyl) methylphosphonate, (2-propynyl)(2-propenyl) ethylphosphonate, (3-butenyl)(2-propynyl) ethylphosphonate, (1,1-dimethyl-2-propynyl)(2-propenyl) ethylphosphonate, and (3-butenyl)(1,1-dimethyl-2-propynyl) ethylphosphonate;

[0359] Phosphoric acid (methyl)(2-propenyl)(2-propynyl), phosphoric acid (ethyl)(2-propenyl)(2-propynyl), phosphoric acid (2-butenyl)(methyl)(2-propynyl), phosphoric acid (2-butenyl)(ethyl)(2-propynyl), phosphoric acid (1,1-dimethyl-2-propynyl)(methyl)(2-propenyl), phosphoric acid (1,1-dimethyl-2-propynyl)(ethyl)(2-propenyl), phosphoric acid (2-butenyl)(1,1-dimethyl-2-propynyl)(methyl), and phosphoric acid (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl) and other phosphate esters;

[0360] Among these, compounds having an alkynyloxy group are preferable because they form a negative electrode film more stably in the electrolytic solution.

[0361] Furthermore, compounds such as 2-propynyl methyl 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 preferable from the viewpoint of improving storage characteristics.

[0362] The compounds having the above triple bond may be used alone or in combination of two or more in any combination and ratio. There is no limit to the blending amount of the compound having a triple bond with respect to the entire electrolytic solution of the present disclosure, and it is arbitrary as long as the effects of the present disclosure are not significantly impaired. However, with respect to the electrolytic solution of the present disclosure, it is usually 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 satisfied, the effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

[0363] In the electrolytic solution of the present disclosure, an overcharge inhibitor can be used in order to effectively suppress battery rupture and ignition when the electrochemical device using the electrolytic solution is in a state such as overcharge.

[0364] Examples of overcharge preventives include terphenyl derivatives which are unsubstituted or substituted with an alkyl group such as biphenyl, o - terphenyl, m - terphenyl, p - terphenyl, partial hydrides of terphenyl derivatives which are unsubstituted or substituted with an alkyl group, cyclohexylbenzene, t - butylbenzene, t - amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3 - trimethyl - 3 - phenylindane, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3 - diisopropylbenzene, 1,4 - diisopropylbenzene, t - butylbenzene, t - amylbenzene, t - hexylbenzene, anisole and other aromatic compounds; partially fluorinated products of the above aromatic compounds such as 2 - fluorobiphenyl, 4 - fluorobiphenyl, o - cyclohexylfluorobenzene, p - cyclohexylfluorobenzene, o - cyclohexylfluorobenzene, p - cyclohexylfluorobenzene, fluorobenzene, fluorotoluene, benzotrifluoride; fluorinated anisole compounds such as 2,4 - difluoroanisole, 2,5 - difluoroanisole, 1,6 - difluoroanisole, 2,6 - difluoroanisole, 3,5 - difluoroanisole; aromatic acetates such as 3 - propylphenyl acetate, 2 - ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, phenethylphenyl acetate; aromatic carbonates such as diphenyl carbonate, methylphenyl carbonate; toluene derivatives such as toluene, xylene; biphenyl derivatives which are unsubstituted or substituted with an alkyl group such as 2 - methylbiphenyl, 3 - methylbiphenyl, 4 - methylbiphenyl, o - cyclohexylbiphenyl and the like. Among them, biphenyl, alkylbiphenyl, terphenyl, partial hydrogenated terphenyl, aromatic compounds such as cyclohexylbenzene, t - butylbenzene, t - amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3 - trimethyl - 3 - phenylindane, 3 - propylphenyl acetate, 2 - ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, methylphenyl carbonate and the like are preferred.These may be used alone or in combination of two or more. When using two or more in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, 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 are preferably used in combination from the viewpoint of the balance between overcharge prevention characteristics and high-temperature storage characteristics.

[0365] A carboxylic anhydride (excluding compound (2)) may be used in the electrolytic solution used in the present disclosure. As the above carboxylic anhydride, a compound represented by the following general formula (6) is preferable. The production method of the carboxylic anhydride is not particularly limited, and a known method can be arbitrarily selected for production.

[0366]

Chemical formula

[0367] R 61 , R 62 As long as it is a monovalent hydrocarbon group, its type is not particularly limited. For example, it may be an aliphatic hydrocarbon group, 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). Further, the aliphatic hydrocarbon group may be linear or cyclic, and in the case of linear, it may be straight-chain or branched-chain. Furthermore, a combination of linear and cyclic may also be possible. Note that R 61 and R 62 may be the same as or different from each other.

[0368] Also, when the hydrocarbon group of R 61 , R 62 has a substituent, the type of the substituent is not particularly limited as long as it does not conflict with the gist of the present disclosure. Examples thereof include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and preferably a fluorine atom. Alternatively, as substituents other than halogen atoms, substituents having functional groups such as an ester group, a cyano group, a carbonyl group, and an ether group can also be mentioned, and preferably a cyano group and a carbonyl group. R 61 , R 62 's hydrocarbon group may have only one of these substituents or may have two or more thereof. When having two or more substituents, these substituents may be the same or different from each other.

[0369] R 61 , R 62 's each hydrocarbon group usually has 1 or more carbon atoms, and usually 15 or less, preferably 12 or less, more preferably 10 or less, and still more preferably 9 or less. When R 61 and R 62 are bonded to each other to form a divalent hydrocarbon group, the carbon number of the divalent hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 13 or less, more preferably 10 or less, and still more preferably 8 or less. In addition, when the hydrocarbon group of R 61 , R 62 has a substituent containing a carbon atom, it is preferable that the total carbon number of R 61 , R 62 including the substituent satisfies the above range.

[0370] Next, specific examples of the acid anhydride represented by the above general formula (6) will be described. In the following examples, the "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure within a range not conflicting with the gist of the present disclosure. For example, dimers, trimers, and tetramers composed of a plurality of acid anhydrides, or structural isomers such as those having the same carbon number of substituents but having a branched chain, and those having different bonding sites of the substituents to the acid anhydride, etc. can be mentioned.

[0371] First, specific examples of acid anhydrides where R 61 and R 62 are the same are given below.

[0372] R 61 and R 62 are linear alkyl groups. Specific examples of acid anhydrides include 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 the like, and analogs thereof.

[0373] R 61 and R 62 are cyclic alkyl groups. Specific examples of acid anhydrides include cyclopropanecarboxylic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, and the like, and analogs thereof.

[0374] R 61 and R 62 are alkenyl groups. Specific examples of acid anhydrides 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 anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-thenoic anhydride, 2-methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentene carboxylic anhydride, 3-cyclopentene carboxylic anhydride, 4-cyclopentene carboxylic anhydride, and the like, and analogs thereof.

[0375] R 61 , R 62 Specific examples of acid anhydrides in which is an alkynyl group include propynoic anhydride, 3-phenylpropynoic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride, 4-pentynoic anhydride, and analogs thereof.

[0376] R 61 , R 62 Specific examples of acid anhydrides in which is an aryl group include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 2-methylbenzoic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, 2-naphthalenecarboxylic anhydride, and analogs thereof.

[0377] Also, R 61 , R 62 As examples of acid anhydrides in which halogen atoms are substituted, examples of acid anhydrides in which fluorine atoms are mainly substituted are given below, but 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 exemplified compounds.

[0378] R 61 , R 62 Examples of acid anhydrides in which is a chain alkyl group 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 the like, and analogs thereof.

[0379] R61 and R 62 Examples of acid anhydrides in which R is a cyclic alkyl group substituted with a halogen atom include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, 4-fluorocyclopentanecarboxylic anhydride, and the like, and their analogs and the like.

[0380] R 61 and R 62 Examples of acid anhydrides in which R 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, 2-(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 anhydride, 2,2-difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3,4-trifluoro-3-butenoic anhydride, and the like, and their analogs and the like.

[0381] R 61 and R 62 Examples of acid anhydrides in which R is an alkynyl group substituted with a halogen atom include 3-fluoro-2-propynoic anhydride, 3-(4-fluorophenyl)-2-propynoic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propynoic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride, 4,4,4-trifluoro-2-butynoic anhydride, and the like, and their analogs and the like.

[0382] R 61 and R 62Examples 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 the like, and their analogs.

[0383] R 61 、R 62 Examples of acid anhydrides having a substituent having a functional group such as an ester, nitrile, ketone, ether, etc. include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutyric anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and the like, and their analogs.

[0384] Subsequently, specific examples of acid anhydrides in which R 61 、R 62 are different from each other are given below.

[0385] R 61 、R 62 As R

[0386] Examples of combinations of chain alkyl groups include acetic propionic anhydride, acetic butyric anhydride, butyric propionic anhydride, acetic 2-methylpropionic anhydride, and the like.

[0387] Examples of combinations of a chain alkyl group and a cyclic alkyl group include acetic cyclopentanoic anhydride, acetic cyclohexanoic anhydride, cyclopentanoic propionic anhydride, and the like.

[0388] Examples of combinations of a chain alkyl group and an alkenyl group include acetic acrylic anhydride, acetic 3-methylacrylic anhydride, acetic 3-butenoic anhydride, acrylic propionic anhydride, and the like.

[0389] Examples of combinations of a chain alkyl group and an alkynyl group include propionic acetic anhydride, 2-butynoic acetic anhydride, 3-butynoic acetic anhydride, 3-phenylpropynoic acetic anhydride, propionic propynoic anhydride, and the like.

[0390] Examples of combinations of a chain alkyl group and an aryl group include benzoic acetic anhydride, 4-methylbenzoic acetic anhydride, 1-naphthalenecarboxylic acetic anhydride, propionic benzoic anhydride, and the like.

[0391] Examples of combinations of a chain alkyl group and a hydrocarbon group having a functional group include fluoroacetic acetic anhydride, trifluoroacetic acetic anhydride, 4-fluorobenzoic acetic anhydride, fluoroacetic propionic anhydride, alkyl oxalic acetic anhydride, 2-cyanoacetic acetic anhydride, 2-oxopropionic acetic anhydride, methoxyacetic acetic anhydride, methoxyacetic propionic anhydride, and the like.

[0392] Examples of combinations of cyclic alkyl groups include cyclopentanoic cyclohexanoic anhydride, and the like.

[0393] Examples of combinations of a cyclic alkyl group and an alkenyl group include acrylic cyclopentanoic anhydride, 3-methylacrylic cyclopentanoic anhydride, 3-butenoic cyclopentanoic anhydride, acrylic cyclohexanoic anhydride, and the like.

[0394] Examples of combinations of a cyclic alkyl group and an alkynyl group include propiolic cyclopentanoic anhydride, 2-butynoic cyclopentanoic anhydride, propiolic cyclohexanoic anhydride, and the like.

[0395] Examples of combinations of a cyclic alkyl group and an aryl group include benzoic cyclopentanoic anhydride, 4-methylbenzoic cyclopentanoic anhydride, benzoic cyclohexanoic anhydride, and the like.

[0396] Examples of combinations of a cyclic alkyl group and a hydrocarbon group having a functional group include cyclopentane fluoroacetate anhydride, cyclopentane trifluoroacetate anhydride, cyclopentane 2-cyanoacetate anhydride, cyclopentane methoxyacetate anhydride, cyclohexane fluoroacetate anhydride, and the like.

[0397] Examples of combinations of alkenyl groups include 2-methylacrylic acid acrylate anhydride, 3-methylacrylic acid acrylate anhydride, 3-butenoic acid acrylate anhydride, 3-methylacrylic acid 2-methylacrylate anhydride, and the like.

[0398] Examples of combinations of an alkenyl group and an alkynyl group include propiolic acid acrylate anhydride, 2-butynoic acid acrylate anhydride, 2-methylpropiolic acid acrylate anhydride, and the like.

[0399] Examples of combinations of an alkenyl group and an aryl group include benzoic acid acrylate anhydride, 4-methylbenzoic acid acrylate anhydride, 2-methylbenzoic acid acrylate anhydride, and the like.

[0400] Examples of combinations of an alkenyl group and a hydrocarbon group having a functional group include fluoroacetic acid acrylate anhydride, trifluoroacetic acid acrylate anhydride, 2-cyanoacetic acid acrylate anhydride, methoxyacetic acid acrylate anhydride, 2-methylfluoroacetic acid acrylate anhydride, and the like.

[0401] Examples of combinations of alkynyl groups include 2-butynoic acid propiolic acid anhydride, 3-butynoic acid propiolic acid anhydride, 3-butynoic acid 2-butynoic acid anhydride, and the like.

[0402] Examples of combinations of an alkynyl group and an aryl group include propiolic acid benzoate anhydride, 4-methylpropiolic acid benzoate anhydride, 2-butynoic acid benzoate anhydride, and the like.

[0403] Examples of combinations of a hydrocarbon group having an alkynyl group and a functional group include fluoroacetic anhydride propionate, trifluoroacetic anhydride propionate, 2-cyanoacetic anhydride propionate, methoxyacetic anhydride propionate, fluoroacetic anhydride 2-butynoate, and the like.

[0404] Examples of combinations of aryl groups include benzoic anhydride 4-methylbenzoate, benzoic anhydride 1-naphthalenecarboxylate, 4-methylbenzoic anhydride 1-naphthalenecarboxylate, and the like.

[0405] Examples of combinations of an aryl group and a hydrocarbon group having a functional group include fluoroacetic anhydride benzoate, trifluoroacetic anhydride benzoate, 2-cyanoacetic anhydride benzoate, methoxyacetic anhydride benzoate, fluoroacetic anhydride 4-methylbenzoate, and the like.

[0406] Examples of combinations of hydrocarbon groups having a functional group include fluoroacetic anhydride trifluoroacetate, fluoroacetic anhydride 2-cyanoacetate, fluoroacetic anhydride methoxyacetate, trifluoroacetic anhydride 2-cyanoacetate, and the like.

[0407] Among the acid anhydrides forming the above chain structure, preferably, acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, etc., acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, propiolic anhydride, 2-butynoic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3-trifluoropropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride, and more preferably, 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, ethoxyformic anhydride.

[0408] These compounds are preferably from the viewpoint that they can appropriately form a bond with lithium oxalate salt to form a film with excellent durability, and can particularly improve the charge-discharge rate characteristics, input-output characteristics, and impedance characteristics after the durability test.

[0409] Note that there is no limitation on the molecular weight of the above carboxylic anhydride, and it is arbitrary as long as the effects of the present disclosure are not significantly impaired. Usually, it is 90 or more, preferably 95 or more. On the other hand, usually, it is 300 or less, preferably 200 or less. When the molecular weight of the carboxylic anhydride is within the above range, an increase in the viscosity of the electrolytic solution can be suppressed, and the film density can be optimized, so that the durability can be appropriately improved.

[0410] Also, the method for producing the carboxylic anhydride is not particularly limited, and a known method can be arbitrarily selected for production. Any one of the carboxylic anhydrides described above may be contained alone in the non-aqueous electrolyte of the present disclosure, or two or more thereof may be contained in any combination and ratio.

[0411] Also, the content of the carboxylic anhydride in the electrolyte of the present disclosure is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. However, for the electrolyte of the present disclosure, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less. It is desirable to contain it at a concentration. When the content of the carboxylic anhydride is within the above range, the effect of improving the cycle characteristics is likely to appear, and the reactivity is suitable, so the battery characteristics are likely to be improved.

[0412] Known other auxiliaries can be used in the electrolyte of the present disclosure. Other auxiliaries 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, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; fluorinated 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, fluorinated biphenyl; carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxapentadecane, ethoxymethoxyethane, trimethoxymethane, glyme, ethyl monoglyme; Ketone compounds such as dimethyl ketone, diethyl ketone, 3-pentanone; Acid anhydrides such as 2-allyl succinic anhydride; Ester compounds such as dimethyl oxalate, diethyl oxalate, ethyl methyl oxalate, di(2-propynyl) oxalate, methyl 2-propynyl oxalate, dimethyl succinate, di(2-propynyl) glutarate, methyl formate, ethyl formate, 2-propynyl formate, 2-butyn-1,4-diyl diformate, 2-propynyl methacrylate, dimethyl malonate; Amide compounds such as acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide; Sulfur-containing compounds such as 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, propane disulfonic anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethane disulfonic anhydride, methylene methanedisulfonate, 2-propynyl methanesulfonate, pentene sulfite, pentafluorophenyl methanesulfonate, propylene sulfate, propylene sulfite, propanesultone, butylene sulfite, butane-2,3-diyl dimethanesulfonate, 2-butyne-1,4-diyl dimethanesulfonate, 2-propynyl vinylsulfonate, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, 2-propynyl 2-(methanesulfonyloxy)propionate, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxide, 3-sulfo-propionic anhydride trimethylene methanedisulfonate 2-methyltetrahydrofuran, trimethylene methanedisulfonate, tetramethylene sulfoxide, dimethylene methanedisulfonate, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, ethylene bis(methyl sulfonate), ethylene bis(ethyl sulfonate), ethylene sulfate, 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, ethylenediamine; Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, ethyl diethylphosphonoacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide, bis(2,2-difluoroethyl) 2,2,2-trifluoroethyl phosphate, bis(2,2,3,3-tetrafluoropropyl) 2,2,2-trifluoroethyl phosphate, 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 phosphate, tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, trioctyl phosphate, 2-phenylphenyl dimethyl phosphate, 2-phenylphenyl diethyl 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, methylenebisphosphonic acid methyl, methylenebisphosphonic acid ethyl, ethylenebisphosphonic acid methyl, ethylenebisphosphonic acid ethyl, butylenebisphosphonic acid methyl, butylenebisphosphonic acid ethyl, 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) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) phosphite, trimethylsilyl polyphosphate and other phosphorus-containing compounds; Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; Silane compounds such as dimethoxyaluminoxytriethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytriethoxysilane, dibutoxyaluminoxytriethoxysilane, titanium tetrakis(trimethylsiloxide), titanium tetrakis(triethylsiloxide), and tetramethylsilane; etc. These may be used alone or in combination of two or more. By adding these auxiliaries, the capacity retention characteristics and cycle characteristics after high-temperature storage can be improved. Among the above-mentioned other auxiliaries, phosphorus-containing compounds are particularly preferred, and tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite are preferred.

[0413] The blending amount of other auxiliaries is not particularly limited and is arbitrary as long as the effects of the present disclosure are not significantly impaired. Other auxiliaries are preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the electrolyte. Within this range, the effects of other auxiliaries are likely to be fully exhibited, and it is also easy to avoid situations such as deterioration of battery characteristics such as high-load discharge characteristics. The blending amount of other auxiliaries is more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and more preferably 3% by mass or less, still more preferably 1% by mass or less.

[0414] The electrolyte of the present disclosure may further contain, as additives, cyclic and chain carboxylic acid esters, ether compounds, nitrogen-containing compounds, boron-containing compounds, organosilicon-containing compounds, flame retardants, surfactants, high-dielectric additives, cycle and rate characteristic improvers, sulfone-based compounds, etc., as long as the effects of the present disclosure are not impaired.

[0415] Examples of the cyclic carboxylic acid ester include those having 3 to 12 carbon atoms in total in the structural formula. Specifically, γ-butyrolactone, γ-valerolactone, γ-caprolactone, ε-caprolactone, 3-methyl-γ-butyrolactone and the like can be mentioned. Among them, γ-butyrolactone is particularly preferable from the viewpoint of improving the characteristics of the electrochemical device due to the improvement of the lithium ion dissociation degree.

[0416] The blending amount of the cyclic carboxylic acid ester as an additive is usually preferably 0.1% by mass or more, more preferably 1% by mass or more in 100% by mass of the solvent. Within this range, the electric conductivity of the electrolytic solution is improved, and the high current discharge characteristics of the electrochemical device are easily improved. Further, the blending amount of the cyclic carboxylic acid ester is preferably 10% by mass or less, more preferably 5% by mass or less. By setting the upper limit in this way, the viscosity of the electrolytic solution is set within an appropriate range, a decrease in electric conductivity is avoided, an increase in negative electrode resistance is suppressed, and the high current discharge characteristics of the electrochemical device are easily set within a good range.

[0417] Further, as the cyclic carboxylic acid ester, a fluorinated cyclic carboxylic acid ester (fluorine-containing lactone) can also be preferably used. Examples of the fluorine-containing lactone include the following formula (C):

[0418]

Chemical formula

[0419] (In the formula, X 15 ~X 20 are the same or different and are each -H, -F, -Cl, -CH 3 or a fluorinated alkyl group; provided that at least one of X 15 ~X 20 is a fluorinated alkyl group) The fluorine-containing lactone represented by the formula can be mentioned.

[0420] X 15 ~X 20 Examples of the fluorinated alkyl group in include, for example, -CFH2 , -CF 2 H, -CF 3 , -CH 2 CF 3 , -CF 2 CF 3 , -CH 2 CF 2 CF 3 , -CF(CF 3 ) 2 etc. can be mentioned. From the point of high oxidation resistance and the effect of improving safety, -CH 2 CF 3 , -CH 2 CF 2 CF 3 is preferred.

[0421] X 15 ~X 20 If at least one of them is a fluorinated alkyl group, -H, -F, -Cl, -CH 3 or the fluorinated alkyl group may be substituted at only one position of X 15 ~X 20 or may be substituted at multiple positions. Preferably, from the point of good solubility of the electrolyte salt, it is 1 to 3 positions, more preferably 1 to 2 positions.

[0422] The substitution position of the fluorinated alkyl group is not particularly limited. However, from the point of good synthesis yield, X 17 and / or X 18 are particularly such that X 17 or X 18 is a fluorinated alkyl group, especially -CH 2 CF 3 , -CH 2 CF 2 CF 3 is preferred. X 15 ~X 20 other than the fluorinated alkyl group are -H, -F, -Cl or CH 3 and -H is preferred particularly from the point of good solubility of the electrolyte salt.

[0423] As the fluorine-containing lactone, in addition to those represented by the above formula, for example, the following formula (D):

[0424] [Chemical formula]

[0425] (In the formula, either A or B is CX 226 X 227 (X 226 and X 227 are the same or different and are each -H, -F, -Cl, -CF 3 , -CH 3 or an alkylene group in which a hydrogen atom may be substituted with a halogen atom and which may contain a hetero atom in the chain), and the other is an oxygen atom; Rf 12 is a fluorinated alkyl group or a fluorinated alkoxy group which may have an ether bond; X 221 and X 222 are the same or different and are each -H, -F, -Cl, -CF 3 or CH 3 ; X 223 ~X 225 are the same or different and are each -H, -F, -Cl or an alkyl group in which a hydrogen atom may be substituted with a halogen atom and which may contain a hetero atom in the chain; n = 0 or 1) Fluorinated lactones represented by the formula are also included.

[0426] As the fluorinated lactone represented by the formula (D), the following formula (E):

[0427] [Chemical formula]

[0428] (In the formula, A, B, Rf 12 , X 221 , X 222 and X 223 are the same as those in the formula (D)) The 5-membered ring structure represented by the formula is preferably mentioned because of the ease of synthesis and the good chemical stability. Furthermore, depending on the combination of A and B, the following formula (F):

[0429] [Chemical formula]

[0430] (wherein, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 are the same as formula (D)) a fluorine-containing lactone represented by the following formula (G):

[0431]

Chemical formula

[0432] (wherein, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 are the same as formula (D)) There is a fluorine-containing lactone represented by the following formula (G).

[0433] Among these, from the viewpoints that excellent characteristics such as high dielectric constant and high breakdown voltage can be particularly exhibited, and that the solubility of the electrolyte salt and the reduction of the internal resistance are good, the characteristics as an electrolytic solution in the present disclosure are improved,

[0434]

Chemical formula

[0435] Examples of the above-mentioned chain carboxylic acid esters include those having 3 to 7 carbon atoms in total in their structural formulas. Specifically, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, isopropyl isobutyrate, etc. may be mentioned.

[0436] Among them, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. are preferable from the viewpoint of improving ionic conductivity due to a decrease in viscosity.

[0437] As the above-mentioned ether compound, a chain ether having 2 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms are preferable. Examples of the chain ether 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, diisopropyl ether, etc.

[0438] In addition, as the above-mentioned ether compound, a fluorinated ether can also be suitably used. Examples of the above-mentioned fluorinated ether include the following general formula (I): Rf 3 -O-Rf 4 (I) (In the formula, Rf3 and Rf 4 are the same or different and are an alkyl group having 1 to 10 carbon atoms or a fluorinated alkyl group having 1 to 10 carbon atoms. However, Rf 3 and Rf 4 at least one of which is a fluorinated alkyl group.) Examples thereof include a fluorinated ether (I) represented by the formula. By containing the fluorinated ether (I), the flame retardancy of the electrolytic solution is improved, and the stability and safety at high temperature and high voltage are improved.

[0439] In the above general formula (I), Rf 3 and Rf 4 at least one of which may be a fluorinated alkyl group having 1 to 10 carbon atoms. However, from the viewpoint of further improving the flame retardancy, stability, and safety of the electrolytic solution at high temperature and high voltage, Rf 3 and Rf 4 are preferably both fluorinated alkyl groups having 1 to 10 carbon atoms. In this case, Rf 3 and Rf 4 may be the same or different from each other. Among them, Rf 3 and Rf 4 are the same or different, Rf 3 is a fluorinated alkyl group having 3 to 6 carbon atoms, and Rf 4 is more preferably a fluorinated alkyl group having 2 to 6 carbon atoms.

[0440] Rf 3 and Rf 4 If the total number of carbon atoms of Rf 3 and Rf 4 is too small, the boiling point of the fluorinated ether becomes too low. On the other hand, if the number of carbon atoms of Rf 3 or Rf 4 is too large, the solubility of the electrolyte salt decreases, the compatibility with other solvents starts to deteriorate, and the viscosity increases, resulting in a reduction in rate characteristics. It is advantageous in terms of excellent boiling point and rate characteristics when the number of carbon atoms of Rf 3 is 3 or 4 and the number of carbon atoms of Rf 4 is 2 or 3.

[0441] The above fluorinated ether (I) preferably has a fluorine content of 40 to 75% by mass. When it has a fluorine content within this range, it becomes particularly excellent in the balance between nonflammability and compatibility. It is also preferable in terms of good oxidation resistance and safety. The lower limit of the above fluorine content is more preferably 45% by mass, still more preferably 50% by mass, and particularly preferably 55% by mass. The upper limit is more preferably 70% by mass, and still more preferably 66% by mass. The fluorine content of the fluorinated ether (I) is a value calculated by {(number of fluorine atoms × 19) / molecular weight of the fluorinated ether (I)} × 100 (%) based on the structural formula of the fluorinated ether (I).

[0442] Rf 3 Examples of Rf 3 CF 2 CH 2 -、CF 3 CFHCF 2 -、HCF 2 CF 2 CF 2 -、HCF 2 CF 2 CH 2 -、CF 3 CF 2 CH 2 CH 2 -、CF 3 CFHCF 2 CH 2 -、HCF 2 CF 2 CF 2 CF 2 -、HCF 2 CF 2 CF 2 CH 2 -、HCF 2 CF 2 CH 2 CH 2 -、HCF 2 CF(CF 3 )CH 2 - etc. can be mentioned. Also, examples of Rf 4 include, for example, -CH 2 CF 2 CF 3 、-CF 2CFHCF 3 ,-CF 2 CF 2 CF 2 H, -CH 2 CF 2 CF 2 H, -CH 2 CH 2 CF 2 CF 3 ,-CH 2 CF 2 CFHCF 3 ,-CF 2 CF 2 CF 2 CF 2 H, -CH 2 CF 2 CF 2 CF 2 H, -CH 2 CH 2 CF 2 CF 2 H, -CH 2 CF(CF 3 )CF 2 H, -CF 2 CF 2 H, -CH 2 CF 2 H, -CF 2 CH 3 etc. can be mentioned.

[0443] Specific examples of the above fluorinated ether (I) include, for example, HCF 2 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CF 2 CH 2 OCF 2 CF 2 H, HCF 2 CF 2 CH 2 OCF 2 CFHCF 3 , CF 3 CF 2 CH 2 OCF 2 CFHCF 3 , C 6 F 13 OCH 3 , C6 F 13 OC 2 H 5 、C 8 F 17 OCH 3 、C 8 F 17 OC 2 H 5 、CF 3 CFHCF 2 CH(CH 3 )OCF 2 CFHCF 3 、HCF 2 CF 2 OCH(C 2 H 5 ) 2 、HCF 2 CF 2 OC 4 H 9 、HCF 2 CF 2 OCH 2 CH(C 2 H 5 ) 2 、HCF 2 CF 2 OCH 2 CH(CH 3 ) 2 include the following, etc.

[0444] Among them, those containing HCF 2 - or CF 3 CFH- at one or both ends are excellent in polarization and can give a fluorinated ether (I) with a high boiling point. The boiling point of the fluorinated ether (I) is preferably 67 to 120°C. More preferably, it is 80°C or higher, and even more preferably 90°C or higher.

[0445] Examples of such a fluorinated ether (I) include, for example, CF 3 CH 2 OCF 2 CFHCF 3 、CF 3 CF 2 CH 2 OCF 2 CFHCF 3 、HCF 2 CF 2 CH2 OCF 2 CFHCF 3 、HCF 2 CF 2 CH 2 OCH 2 CF 2 CF 2 H、CF 3 CFHCF 2 CH 2 OCF 2 CFHCF 3 、HCF 2 CF 2 CH 2 OCF 2 CF 2 H、CF 3 CF 2 CH 2 OCF 2 CF 2 One or more of H, etc. may be mentioned. Among them, HCF is advantageous in terms of high boiling point, good compatibility with other solvents, and good solubility of electrolyte salts. 2 CF 2 CH 2 OCF 2 CFHCF 3 (Boiling point 106 °C), CF 3 CF 2 CH 2 OCF 2 CFHCF 3 (Boiling point 82 °C), HCF 2 CF 2 CH 2 OCF 2 CF 2 H (boiling point 92 °C) and CF 3 CF 2 CH 2 OCF 2 CF 2 It is preferably at least one selected from the group consisting of H (boiling point 68 °C), CF 2 CF 2 CH 2 OCF 2 CFHCF 3 (Boiling point 106 °C) and HCF 2 CF 2 CH 2 OCF 2 CF 2It is more preferable that it is at least one selected from the group consisting of H (boiling point 92 ° C).

[0446] Examples of the cyclic ether 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, etc., and fluorinated compounds thereof. Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and crown ether are preferable in terms of high solvation ability to lithium ions and improvement of ion dissociation degree. Particularly preferably, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are used because of their low viscosity and high ion conductivity.

[0447] Examples of the nitrogen-containing compound include nitrile, fluorinated nitrile, carboxylic acid amide, fluorinated carboxylic acid amide, sulfonic acid amide, fluorinated sulfonic acid amide, acetamide, formamide, etc. Also, 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide, etc. can also be used. However, the nitrile compounds represented by the above general formulas (1a), (1b), and (1c) are not included in the above nitrogen-containing compounds.

[0448] Examples of the boron-containing compound include boric acid esters such as trimethyl borate and triethyl borate, boric acid ethers, and alkyl borates.

[0449] Examples of the organosilicon-containing compound include, for example, (CH 3 ) 4 -Si, (CH 3 )3 -Si-Si(CH 3 ) 3 , silicone oil, etc. can be mentioned.

[0450] Examples of the non-combustible (flame-retardant) agent include phosphate esters and phosphazene compounds. Examples of the phosphate ester include fluorinated alkyl phosphate esters, non-fluorinated alkyl phosphate esters, aryl phosphate esters, etc. Among them, a fluorinated alkyl phosphate ester is preferable in that it can exhibit a non-combustible effect in a small amount.

[0451] Examples of the phosphazene compound include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, ethoxyheptafluorocyclotetraphosphazene, etc.

[0452] Specific examples of the fluorinated alkyl phosphate ester include the fluorinated dialkyl phosphate ester described in JP-A-11-233141, the cyclic alkyl phosphate ester described in JP-A-11-283669, or the fluorinated trialkyl phosphate ester, etc.

[0453] Examples of the non-combustible (flame-retardant) agent include (CH 3 O) 3 P=O, (CF 3 CH 2 O) 3 P=O, (HCF 2 CH 2 O) 3 P=O, (CF 3 CF 2 CH 2 ) 3 P=O, (HCF 2 CF 2 CH 2 ) 3 P=O, etc. are preferable.

[0454] As the surfactant, any of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant may be used, but from the viewpoint of good cycle characteristics and rate characteristics, it is preferably one containing a fluorine atom.

[0455] Examples of such a surfactant containing a fluorine atom include the following formula (30): Rf 5 COO - M + (30) (In the formula, Rf 5 is a fluorine-containing alkyl group which may contain an ether bond having 3 to 10 carbon atoms; M + is Li + , Na + , K + or NHR’ 3 + (R’ is the same or different, and each is H or an alkyl group having 1 to 3 carbon atoms)) fluorine-containing carboxylate represented by the formula and the following formula (40): Rf 6 SO 3 - M + (40) (In the formula, Rf 6 is a fluorine-containing alkyl group which may contain an ether bond having 3 to 10 carbon atoms; M + is Li + , Na + , K + or NHR’ 3 + (R’ is the same or different, and each is H or an alkyl group having 1 to 3 carbon atoms)) fluorine-containing sulfonate represented by the formula and the like are preferable.

[0456] From the viewpoint of being able to lower the surface tension of the electrolytic solution without degrading the charge and discharge cycle characteristics, the content of the surfactant is preferably 0.01 to 2% by mass in the electrolytic solution.

[0457] Examples of the high-dielectric additive include sulfolane, methyl sulfolane, γ-butyrolactone, γ-valerolactone, and the like.

[0458] Examples of the above cycle property and rate property improvers include methyl acetate, ethyl acetate, tetrahydrofuran, 1,4 - dioxane, and the like.

[0459] Further, the electrolytic solution of the present disclosure may be a gel - like (plasticized) gel electrolytic solution in combination with a polymer material.

[0460] Examples of such polymer materials include conventionally known polyethylene oxide, polypropylene oxide, and modified products thereof (Japanese Patent Laid - Open No. 8 - 222270, Japanese Patent Laid - Open No. 2002 - 100405); polyacrylate - based polymers, polyacrylonitrile, fluororesins such as polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer (Japanese Patent Publication No. 4 - 506726, Japanese Patent Publication No. 8 - 507407, Japanese Patent Laid - Open No. 10 - 294131); composites of these fluororesins and hydrocarbon - based resins (Japanese Patent Laid - Open No. 11 - 35765, Japanese Patent Laid - Open No. 11 - 86630), etc. In particular, it is desirable to use polyvinylidene fluoride or vinylidene fluoride - hexafluoropropylene copolymer as the polymer material for the gel electrolyte.

[0461] In addition, the electrolytic solution of the present disclosure may also contain an ion - conductive compound described in the specification of Japanese Patent Application No. 2004 - 301934.

[0462] This ion - conductive compound has the formula (101): A-(D)-B (101) [wherein, D has the formula (201): -(D1) n -(FAE) m -(AE) p -(Y) q - (201) (wherein, D1 has the formula (2a):

[0463]

Chemical formula

[0464] (wherein, Rf is a fluorine-containing ether group which may have a crosslinkable functional group; R 10 is a group or a bond that binds Rf to the main chain) An ether unit having a fluorine-containing ether group in the side chain represented by; FAE is represented by the formula (2b):

[0465]

Chemical formula

[0466] (wherein, Rfa is a hydrogen atom, a fluorinated alkyl group which may have a crosslinkable functional group; R 11 is a group or a bond that binds Rfa to the main chain) An ether unit having a fluorinated alkyl group in the side chain represented by; AE is represented by the formula (2c):

[0467]

Chemical formula

[0468] (wherein, R 13 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; R 12 is R 13 and a group or a bond that binds to the main chain) An ether unit represented by; Y is a unit containing at least one of the formulas (2d-1) to (2d-3):

[0469]

Chemical formula

[0470] ; 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; provided that n + m is not 0, and the bonding order of D1, FAE, AE and Y is not specified); A and B are the same or different and may be a hydrogen atom, a fluorine atom and / or an alkyl group which may contain a crosslinkable functional group, a phenyl group which may contain a fluorine atom and / or a crosslinkable functional group, -COOH group, -OR (R is a hydrogen atom or a fluorine atom and / or an alkyl group which may contain a crosslinkable functional group), an ester group or a carbonate group (however, when the terminal of D is an oxygen atom, it is not a -COOH group, -OR, an ester group or a carbonate group) It is an amorphous fluorine-containing polyether compound having a fluorine-containing group in the side chain represented by .

[0471] The electrolyte of the present disclosure may contain a sulfone compound. As the sulfone compound, cyclic sulfones having 3 to 6 carbon atoms and chain sulfones having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0472] Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones which are monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, hexamethylene disulfones which are disulfone compounds, etc. Among them, from the viewpoints of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

[0473] As the sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter, sulfolane may also be included and abbreviated as "sulfolanes" in some cases) are preferable. As the sulfolane derivatives, those in which one or more of the hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with fluorine atoms or alkyl groups are preferable.

[0474] 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 preferable in terms of high ionic conductivity and high input / output.

[0475] In addition, examples of the chain sulfone 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, perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, pentafluoroethyl-t-butyl sulfone, and the like.

[0476] Among them, 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, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, trifluoromethyl-t-butyl sulfone, etc. are preferable in terms of high ionic conductivity and high input / output.

[0477] The content of the sulfone-based compound is not particularly limited and can be arbitrary as long as the effects of the present disclosure are not significantly impaired. However, in 100% by volume of the above solvent, it 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, more preferably 30% by volume or less. If the content of the sulfone-based compound is within the above range, the effect of improving the durability such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set within an appropriate range, avoiding a decrease in electrical conductivity, and the input / output characteristics and charge / discharge rate characteristics of the non-aqueous electrolyte secondary battery can be set within an appropriate range.

[0478] From the viewpoint of improving the output characteristics, the electrolyte of the present disclosure preferably contains at least one compound (7) selected from the group consisting of lithium fluorophosphate salts (excluding LiPF 6 ) and lithium salts having an S=O group as an additive. When using the compound (7) as an additive, it is preferable to use a compound other than the compound (7) as the electrolyte salt described above.

[0479] Examples of the lithium fluorophosphate salts include lithium monofluorophosphate (LiPO 3 F), lithium difluorophosphate (LiPO 2 F 2 ), and the like. Examples of the lithium salts having the S=O group include lithium monofluorosulfonate (FSO 3 Li), lithium methyl sulfate (CH 3 OSO 3 Li), lithium ethyl sulfate (C 2 H 5 OSO 3 Li), lithium 2,2,2-trifluoroethyl sulfate, and the like. Among the compounds (7), LiPO 2 F 2 , FSO 3 Li, and C 2 H 5 OSO 3 Li are preferred.

[0480] The content of the compound (7) is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, still more preferably 0.1 to 10% by mass, and particularly preferably 0.1 to 7% by mass with respect to the above electrolyte.

[0481] Other additives may be further added to the electrolyte of the present disclosure as necessary. Examples of the other additives include metal oxides, glass, and the like.

[0482] The electrolyte of the present disclosure preferably contains at least one selected from the group consisting of an unsaturated cyclic carbonate, a compound (2), a nitrile compound, a fluorinated saturated cyclic carbonate, a lithium salt having an S=O group, a lithium fluorophosphate salt (excluding LiPF 6 ), a lithium sulfamate compound, and a silyl ester compound of phosphoric acid or phosphorous acid as an additive. By including these additives, the resistance of the electrochemical device can be further reduced, and the cycle characteristics can be further improved. The above additives include unsaturated cyclic carbonates, compound (3), compound (4), nitrile compounds represented by general formula (1a), fluorinated saturated cyclic carbonates, lithium alkyl sulfate compounds, lithium sulfonate compounds, lithium difluorophosphate (LiPO 2 F 2 ), lithium sulfamate compounds represented by the following general formula (11), and M 301 (OSiR 301 3 ) 3 (M 301 is P or P=O, and R 301 is independently an alkyl group having 1 to 4 carbon atoms), and it is preferably at least one selected from the group consisting of phosphoric acid or phosphorous acid silyl ester compounds represented by the following general formula (11). Vinylene carbonate, vinyl ethylene carbonate, succinic anhydride, maleic anhydride, adiponitrile, fluoroethylene carbonate, difluoroethylene carbonate, C 2 H 5 OSO 3 Li, FSO 3 Li, LiPO 2 F 2 , (CH 3 CH 2 ) 2 NSO 3 Li, (CF 3 CH 2 ) 2 NSO 3 Li, (CF 3 CH 2 )(CH 3 )NSO 3 Li, (CNCH 2 ) 2 NSO 3 Li, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(tert-butyldimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, and tris(tert-butyldimethylsilyl) phosphite, and it is more preferably at least one selected from the group consisting of these. As the above additive, a lithium sulfamate compound represented by the following general formula (11) is particularly preferable. The content of the above additive is preferably 0.001 to 5.0% by mass with respect to the electrolytic solution. More preferably, it is 0.01% by mass or more, still more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and also more preferably 3.0% by mass or less, still more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less. General formula (11):

Chemical formula

[0483] Further, the electrolyte of the present disclosure contains, as an additive, at least one selected from the group consisting of an unsaturated cyclic carbonate, a compound (2), a nitrile compound, a fluorinated saturated cyclic carbonate, anions having an S=O group, fluoro phosphate anions (however, excluding PF 6 - ), sulfamic acid anions, and a silyl ester compound of phosphoric acid or phosphorous acid. By containing these additives, the resistance of the electrochemical device can be further reduced, and the cycle characteristics can be further improved. The above additives are an unsaturated cyclic carbonate, a compound (3), a compound (4), a nitrile compound represented by the general formula (1a), a fluorinated saturated cyclic carbonate, alkyl sulfate anions, sulfonate anions, difluoro phosphate anion (PO 2 F 2 - ), sulfamic acid anions represented by the following general formula (11-1), and M 301 (OSiR 301 3 ) 3 (M 301 is P or P=O, and R 301 is independently an alkyl group having 1 to 4 carbon atoms), and is preferably at least one selected from the group consisting of a silyl ester compound of phosphoric acid or phosphorous acid, vinylene carbonate, vinyl ethylene carbonate, succinic anhydride, maleic anhydride, adiponitrile, fluoroethylene carbonate, difluoroethylene carbonate, C 2 H 5 OSO 3 - , FSO 3 - , PO2 F 2 - ,(CH 3 CH 2 ) 2 NSO 3 - ,(CF 3 CH 2 ) 2 NSO 3 - ,(CF 3 CH 2 )(CH 3 )NSO 3 - ,(CNCH 2 ) 2 NSO 3 - , at least one selected from the group consisting of tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(tert-butyldimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, and tris(tert-butyldimethylsilyl) phosphite is more preferable. As the above additive, sulfamic acid anions represented by the following general formula (11-1) are particularly preferable. The content of the above additive is preferably 0.001 to 5.0% by mass based on the electrolytic solution. More preferably, it is 0.01% by mass or more, still more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and also more preferably 3.0% by mass or less, still more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less. General formula (11-1): [Chemical formula] (In general formula (11-1), R 111 and R 112 are each independently -H, -F, Formula: -O p101 -(SiR 113 2 ) n101 -SiR 114 3 (R 113 and R114 is, independently of one another, an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkenyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkynyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, or an aryl group in which one or more hydrogen atoms may be substituted by fluorine atoms, n101 is an integer of 0 or more, and p101 is 0 or 1.), a group represented by an alkyl group having 1 to 7 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, an alkynyl group having 2 to 7 carbon atoms, an aryl group having 6 to 15 carbon atoms, -SO 2 X 101 (X 101 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.). -SO 3 X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.), or R 111 and R 112 are combined to form a hydrocarbon group having 2 to 7 carbon atoms which may contain a multiple bond in the cyclic structure, and is a substituent, the above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogen atoms may be substituted by fluorine atoms or functional groups having 0 to 7 carbon atoms.).

[0484] Hereinafter, the lithium sulfamate compound represented by the general formula (11) (compound (11)) and the sulfamate anions represented by the general formula (11-1) (anion (11-1)) will be described.

[0485] Compound (11) has the general formula (11):

Chemical formula

[0486] In the general formula (11), R 111 and R 112 are each independently -H, -F, a group represented by the formula: -O p101 -(SiR 113 2 O) n101 -SiR 114 3 (R 113 and R 114 are, independently of each other, an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkenyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkynyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, or an aryl group in which one or more hydrogen atoms may be substituted by fluorine atoms, n101 is an integer of 0 or more, and p101 is 0 or 1.), an alkyl group having 1 to 7 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, an alkynyl group having 2 to 7 carbon atoms, an aryl group having 6 to 15 carbon atoms, -SO 2 X 101 (X 101 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.), -SO 3 X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.), or R 111 and R 112 are bonded to form a hydrocarbon group having 2 to 7 carbon atoms which may contain a multiple bond in the cyclic structure, and the above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogen atoms may be substituted by fluorine or a functional group having 0 to 7 carbon atoms. Note that the number of carbon atoms of each of the above substituents means the number of carbon atoms including the number of carbon atoms of the above functional group.

[0487] The above substituents are -H, -F, the above formula: -O p101 -(SiR 113 2 O) n101 -SiR 114 3 groups represented by, the above alkyl group, the above alkenyl group, the above alkynyl group, the above aryl group, the above -SO 2 X 101 the above -SO 3 X 102 or represent the above hydrocarbon group. The above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogen atoms may be substituted with fluorine or a functional group having 0 to 7 carbon atoms. Examples of the functional groups that the above substituents may have include, for example, a phenyl group, an anisyl group, a benzyl group, a cyano group, a trialkylsilyl group (the carbon number of the alkyl group is preferably 1 to 4), -SO 2 X 103 (X 103 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted with fluorine atoms.), an alkyl group having 1 to 7 carbon atoms in which one or more hydrogen atoms may be substituted with fluorine atoms, a saturated heterocyclic group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms is preferred. The carbon number of the alkyl group in the above X 103 is, for example, 1 to 10.

[0488] In the above R 111 and R 112 , the alkyl group may be linear, branched, or cyclic, and the carbon number is preferably 1 to 10, more preferably 1 to 7. The alkyl group may be a fluoroalkyl group in which a hydrogen atom bonded to carbon is substituted with a fluorine atom, or may be one in which a hydrogen atom bonded to carbon is substituted with the above functional group.

[0489] In the above R 111 and R 112In this case, the alkenyl group may be linear, branched or cyclic, preferably having 2 to 10 carbon atoms, more preferably 2 to 7 carbon atoms. The alkenyl group may be a fluoroalkylene group in which a hydrogen atom bonded to carbon is substituted with a fluorine atom, or may be one in which a hydrogen atom bonded to carbon is substituted with the above functional group.

[0490] The above R 111 and R 112 In this case, the alkynyl group may be linear, branched or cyclic, preferably having 2 to 10 carbon atoms, more preferably 2 to 7 carbon atoms. The alkynyl group may be a fluoroalkynyl group in which a hydrogen atom bonded to carbon is substituted with a fluorine atom, or may be one in which a hydrogen atom bonded to carbon is substituted with the above functional group.

[0491] The above R 111 and R 112 In this case, the aryl group preferably has 6 to 7 carbon atoms. The aryl group may be a fluoroaryl group in which a hydrogen atom bonded to carbon is substituted with a fluorine atom, or may be one in which a hydrogen atom bonded to carbon is substituted with the above functional group.

[0492] The above R 111 and R 112 are of the formula: -O p101 -(SiR 113 2 O) n101 -SiR 114 3 (R 113 and R 114 are, independently of each other, an alkyl group in which one or more hydrogen atoms may be substituted with fluorine atoms, an alkenyl group in which one or more hydrogen atoms may be substituted with fluorine atoms, an alkynyl group in which one or more hydrogen atoms may be substituted with fluorine atoms or an aryl group in which one or more hydrogen atoms may be substituted with fluorine atoms, n101 is an integer of 0 or more, and p101 is 0 or 1. ) and may be a group represented by. The above R 113 and R 114In this case, the alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms preferably has 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms. The alkenyl group and alkynyl group in which one or more hydrogen atoms may be substituted by fluorine atoms preferably have 2 to 10 carbon atoms, more preferably 2 to 7 carbon atoms. The aryl group in which one or more hydrogen atoms may be substituted by fluorine atoms preferably has 6 to 8 carbon atoms, more preferably 6 to 7 carbon atoms. In the above formula, n101 is an integer of 0 or more, preferably 2000 or less, more preferably an integer of 0 to 100, and still more preferably 0 to 10.

[0493] The above R 111 and R 112 may be -SO 2 X 101 (X 101 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.). The alkyl group in the above -SO 2 X 101 group preferably has 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms.

[0494] The above R 111 and R 112 may be -SO 3 X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.). The alkyl group in the above -SO 3 X 102 group preferably has 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms.

[0495] The above R 111 and R 112Specifically, examples include linear alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, pentyl group, i-pentyl group, neopentyl group, sec-pentyl group, 3-pentyl group, tert-pentyl group, hexyl group; cyclic alkyl groups such as cyclopentyl group, cyclohexyl group, norbornyl group, 1-adamantyl group; alkenyl groups such as vinyl group, 1-propenyl group, 2-propenyl group (allyl group), 2-butenyl group, 1,3-butadienyl group; alkynyl groups such as ethynyl group, 1-propynyl group, 2-propynyl group, 2-butynyl group; halogenated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,2,3,3,3-hexafluoropropyl group, heptafluoropropyl group; halogenated alkenyl groups such as 1-fluorovinyl group, 2-fluoroallyl group; alkyl groups having a functional group such as cyanomethyl group; alkyl groups having a saturated heterocyclic group such as 3-pyrrolidinopropyl group; aryl groups such as phenyl group which may have an alkyl substituent, an alkoxy substituent, etc.; aralkyl groups such as phenylmethyl group, phenylethyl group; trialkylsilyl groups such as trimethylsilyl group; trialkylsiloxy groups such as trimethylsiloxy group; sulfonyl groups such as fluorosulfonyl group, trifluoromethanesulfonyl group, pentafluoroethanesulfonyl group, etc., but are not limited thereto.

[0496] Also, when R 111 and R 112 are bonded to form a cyclic structure with the above hydrocarbon group, for example, with the nitrogen atom (N) in General Formula (2), R 111 and R 112It may form a cyclic amino group such as a pyrrolidino group or a piperidino group, or may form a heteroatom-containing heterocyclic amino group such as a 4-morpholino group, a succinimidyl group, or a maleimidyl group. One or more hydrogen atoms bonded to carbon may be substituted with fluorine atoms, or the hydrogen atoms bonded to carbon may be substituted with the above functional groups. Further, the cyclic structure may contain a double bond or a triple bond.

[0497] The above substituents may contain a heteroatom having a valence of 2 to 6. Examples of the heteroatom include an oxygen atom (O), a sulfur atom (S), a nitrogen atom (N), a silicon atom (Si), a phosphorus atom (P), and a boron atom (B). More preferably, it is an oxygen atom, a sulfur atom, or a nitrogen atom.

[0498] R 111 and R 112 are preferably an alkyl group having 1 to 7 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms. These alkyl groups may contain one or more heteroatoms having a valence of 2 to 6 in the structure, and one or more hydrogen atoms may be substituted with fluorine atoms or a functional group having 0 to 6 (preferably 0 to 4, more preferably 0 to 3) carbon atoms. As the above heteroatom, an oxygen atom, a sulfur atom, or a nitrogen atom is preferable, an oxygen atom or a nitrogen atom is more preferable, and a nitrogen atom is still more preferable. The above alkyl group may contain an ether bond (-O-). As the above functional group, a cyano group is preferable.

[0499] Examples of the compound (11) include compounds represented by the following formula.

Chemical formula

Chemical formula

Chemical formula

[0500] In this specification, Me represents a methyl group, Et represents an ethyl group, n-Pr represents a normal propyl group, i-Pr represents an isopropyl group, n-Bu represents a normal butyl group, i-Bu represents an iso-butyl group, s-Bu represents a sec-butyl group, t-Bu represents a tert-butyl group, TMS represents a trimethylsilyl group, and TBDMS represents a tert-butyldimethylsilyl group. Also, when described as follows, R may be bonded to any carbon atom constituting the benzene ring. For example, R may be at any of the o-, m-, and p- positions. [Chemistry] Note that the exemplification of the compounds in this specification includes the geometric isomers (if any) of the compounds and is not limited to the specific examples described.

[0501] Among others, as the compound (11), the compound represented by the following formula is preferable. [Chemistry]

[0502] As the compound (11), a compound represented by the following formula is more preferable. [Chemical formula]

[0503] As the compound (11), a compound represented by the following formula is even more preferable. [Chemical formula]

[0504] The compound (11) may be a compound represented by the following general formula (11a) (hereinafter, also referred to as compound (11a)). General formula (11a): [Chemical formula] (In the formula, R 201 and R 202 are each independently -H, -F, Formula: -O p101 -(SiR 113 2 O) n101 -SiR 114 3 (R 113 and R 114 are, independently of each other, an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkenyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkynyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, or an aryl group in which one or more hydrogen atoms may be substituted by fluorine atoms, n101 is an integer of 0 or more, and p101 is 0 or 1.) A group represented by An alkyl group having 1 to 7 carbon atoms, An alkenyl group having 2 to 7 carbon atoms, An alkynyl group having 2 to 7 carbon atoms, An aryl group having 6 to 15 carbon atoms, -SO 2 X 101 (X 101is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.), or -SO 3 X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms.).) is a substituent, the above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogen atoms may be substituted by fluorine or a functional group having 0 to 7 carbon atoms. However, at least one of R 201 and R 202 is -F.).

[0505] In general formula (11a), it is necessary that at least one of R 201 and R 202 is -F. R in general formula (11a) 201 and R 202 as the above -O p101 -(SiR 113 2 O) n101 -SiR 114 3 , the above alkyl group, the above alkenyl group, the above alkynyl group, the above aryl group, the above -SO 2 X 101 and the above -SO 3 X 102 are the same as R 111 and R 112 in general formula (11).

[0506] Examples of compound (11a) include, for example, compounds represented by the following formula.

Chemical formula

[0507] Among others, examples of compound (11a) include

Chemical formula

[0508] Compound (11) can be produced, for example, by the production method described in International Publication No. 2019 / 188207.

[0509] Anion (11-1) has the general formula (11-1):

Chemical formula

[0510] In general formula (11-1), R 111 and R 112 are each independently -H, -F, Formula: -O p101 -(SiR 113 2 O) n101 -SiR 114 3 (R 113 and R 114 are, independently of each other, an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkenyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, an alkynyl group in which one or more hydrogen atoms may be substituted by fluorine atoms, or an aryl group in which one or more hydrogen atoms may be substituted by fluorine atoms, n101 is an integer of 0 or more, and p101 is 0 or 1. ), an alkyl group having 1 to 7 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, an alkynyl group having 2 to 7 carbon atoms, an aryl group having 6 to 15 carbon atoms, -SO 2 X 101 (X 101 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms. ), -SO 3 X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogen atoms may be substituted by fluorine atoms. ), or, R 111 and R 112 which are bonded to form a cyclic structure and may contain a multiple bond in the cyclic structure, and are substituents that are hydrocarbon groups having 2 to 7 carbon atoms the above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogen atoms may be substituted with fluorine atoms or functional groups having 0 to 7 carbon atoms

[0511] R in general formula (11-1) 111 and R 112 include the same groups as those described for general formula (11), and the preferred examples are also the same

[0512] Specific examples of the anion (11-1) include anions having a structure obtained by removing lithium ions (Li + ) from the compounds exemplified as the compound (11)

[0513] Among others, the anion (11-1) is preferably an anion represented by the following formula

Chemical formula

[0514] More preferably, the anion (11-1) is an anion represented by the following formula

Chemical formula

[0515] Even more preferably, the anion (11-1) is an anion represented by the following formula

Chemical formula

[0516] The electrolyte of the present disclosure preferably has a hydrogen fluoride (HF) content of 1 to 1000 ppm. By containing HF, the film formation of the above-described additive can be promoted. If the HF content is too low, the film formation ability on the negative electrode decreases, and the characteristics of the electrochemical device tend to deteriorate. Also, if the HF content is too high, the oxidation resistance of the electrolyte tends to decrease due to the influence of HF. Even if the electrolyte of the present 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, still more preferably 10 ppm or more, and particularly preferably 20 ppm or more. The HF content is also more preferably 200 ppm or less, still 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 a neutralization titration method.

[0517] The electrolyte of the present disclosure may be prepared by any method using the above-described components.

[0518] The electrolyte of the present disclosure can be suitably applied to electrochemical devices such as, for example, lithium-ion secondary batteries, lithium-ion capacitors, hybrid capacitors, and electric double layer capacitors. Hereinafter, a non-aqueous electrolyte battery using the electrolyte of the present disclosure will be described. The non-aqueous electrolyte battery can adopt a known structure and typically includes a positive electrode and a negative electrode capable of occluding and releasing ions (for example, lithium ions) and the electrolyte of the present disclosure. Such an electrochemical device including the electrolyte of the present disclosure is also one of the present disclosures.

[0519] Examples of the electrochemical device include a lithium ion secondary battery, a lithium ion capacitor, a capacitor (hybrid capacitor, electric double layer capacitor), a radical battery, a solar cell (particularly a dye-sensitized solar cell), a lithium ion primary battery, a fuel cell, various electrochemical sensors, an electrochromic element, an electrochemical switching element, an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, etc. Among them, a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor are preferable. A module including the above electrochemical device is also one aspect of the present disclosure.

[0520] The present disclosure also relates to a lithium ion secondary battery including the electrolyte of the present disclosure. The above lithium ion secondary battery preferably includes a positive electrode, a negative electrode, and the above electrolyte.

[0521] <Positive electrode> The positive electrode is composed of a positive electrode active material layer containing a positive electrode active material and a current collector.

[0522] The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Examples thereof include lithium-containing transition metal composite oxides, lithium-containing transition metal phosphate compounds, sulfur-based materials, conductive polymers, etc. Among them, as the positive electrode active material, lithium-containing transition metal composite oxides and lithium-containing transition metal phosphate compounds are preferable, and particularly, lithium-containing transition metal composite oxides that produce a high voltage are preferable.

[0523] As the transition metal of the lithium-containing transition metal composite oxide, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable. Specific examples include lithium-cobalt composite oxides such as LiCoO 2 and lithium-nickel composite oxides such as LiNiO 2 and lithium-manganese composite oxides such as LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 4Lithium-manganese composite oxides such as these, and those in which some of the transition metal atoms that are the main components 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, W, etc. Specific examples of the substituted ones include, for example, LiNi 0.5 Mn 0.5 O 2 、LiNi 0.85 Co 0.10 Al 0.05 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.33 Co 0.33 Mn 0.33 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.45 Co 0.10 Al 0.45 O 2 、LiMn 1.8 Al 0.2 O 4 、LiMn 1.5 Ni 0.5 O 4 and the like.

[0524] Among them, as the above lithium-containing transition metal composite oxides, LiMn 1.5 Ni 0.5 O 4 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 are preferred. Among them, in the case of a high voltage of 4.4 V or more, LiMn 1.5 Ni 0.5 O 4is preferred.

[0525] Among them, as the lithium-containing transition metal composite oxide, from the viewpoint of providing a high-capacity lithium-ion secondary battery, LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.85 Co 0.10 Al 0.05 O 2 is preferred.

[0526] As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferred. Specific examples include, for example, LiFePO 4 、Li 3 Fe 2 (PO 4 ) 3 、LiFeP 2 O 7 and other iron phosphates, LiCoPO 4 and other cobalt phosphates, and those in which a part of the transition metal atoms that are the main components 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, Si, etc.

[0527] As the lithium-containing transition metal composite oxide, for example, Formula: Li a Mn 2-b M 1 b O 4 (In the formula, 0.9 ≦ a; 0 ≦ b ≦ 1.5; M 1 is 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), a lithium-manganese spinel composite oxide represented by Formula: LiNi 1-c M 2 c O2 (where 0 ≦ c ≦ 0.5; M 2 is 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 3 d O 2 (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) is mentioned.

[0528] Among them, from the point that a lithium ion secondary battery with high energy density and high output can be provided, LiCoO 2 , LiMnO 2 , LiNiO 2 , LiMn 2 O 4 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , or LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 is preferable.

[0529] As other above-mentioned positive electrode active materials, LiFePO 4 , LiNi 0.8 Co 0.2 O 2 , Li 1.2 Fe 0.4 Mn 0.4 O 2 , LiNi 0.5 Mn 0.5 O 2 , LiV 3 O 6 , Li 2 MnO 3 etc. are mentioned.

[0530] 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 preferable, and elemental sulfur is more preferable. The metal sulfide may be a metal polysulfide. The organic sulfur compound may be an organic polysulfide.

[0531] Examples of the metal sulfide include LiS x compounds represented by (0 < x ≦ 8); Li 2 S x compounds represented by (0 < x ≦ 8); TiS 2 and MoS 2 compounds having a two-dimensional layered structure such as; general formula Me x Mo 6 S 8 (Me is various transition metals including Pb, Ag, Cu, etc.) and Shubrel compounds having a strong three-dimensional skeleton structure.

[0532] Examples of the organic sulfur compound include carbon sulfide compounds.

[0533] The organic sulfur compound may be supported on a material having pores 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, still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 85% by mass or less with respect to the carbon composite material, since the cycle performance is further improved and the overvoltage is further reduced. When the positive electrode active material is the elemental sulfur, the sulfur content contained in the positive electrode active material is equal to the content of the elemental sulfur.

[0534] Examples of the conductive polymer include p-doped conductive polymers and n-doped conductive polymers. Examples of the conductive polymer include polyacetylene-based, polyphenylene-based, heterocyclic polymers, ionic polymers, ladder and network polymers.

[0535] In addition, it is preferable to include lithium phosphate in the positive electrode active material because the continuous charging characteristics are improved. There is no limitation on the use of lithium phosphate, but it is preferably used by mixing it with the above-described positive electrode active material. The amount of lithium phosphate to be used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more, based on the total of the above positive electrode active material and lithium phosphate, and the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 5% by mass or less.

[0536] Alternatively, a material having a composition different from that of the positive electrode active material may be used on the surface of the positive electrode active material. Examples of the surface-attached substance 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.

[0537] These surface-attached substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending them in a solvent, impregnating and adding them to the positive electrode active material, and then drying; a method of dissolving or suspending a surface-attached substance precursor in a solvent, impregnating and adding it to the positive electrode active material, and then reacting it by heating or the like; or a method of adding it to a positive electrode active material precursor and firing it simultaneously. In the case of attaching carbon, a method of mechanically attaching a carbonaceous material in the form of, for example, activated carbon can also be used.

[0538] The amount of the surface-attached substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and preferably 20% or less, more preferably 10% or less, still more preferably 5% or less by mass with respect to the positive electrode active material. The surface-attached substance can suppress the oxidation reaction of the electrolytic solution on the surface of the positive electrode active material and improve the battery life. However, if the attached amount is too small, the effect cannot be fully exhibited, and if it is too large, the resistance may increase because the entry and exit of lithium ions are inhibited.

[0539] Examples of the shape of the particles of the positive electrode active material include a massive shape, a polyhedral shape, a spherical shape, an ellipsoidal spherical shape, a plate shape, a needle shape, a columnar shape, etc., as conventionally used. Further, the primary particles may aggregate to form secondary particles.

[0540] The tap density of the positive electrode active material is usually 1.5 g / cm 3 or more, preferably 2.0 g / cm 3 or more, still more preferably 2.5 g / cm 3 or more, and most preferably 3.0 g / cm 3 or more. When the tap density of the positive electrode active material is lower than the above lower limit, the required amount of the dispersion medium increases during the formation of the positive electrode active material layer, and the required amounts of the conductive material and the binder increase, and the filling rate of the positive electrode active material in the positive electrode active material layer is restricted, and the battery capacity may be restricted. By using a metal composite oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. Generally, the higher the tap density, the more preferable, and there is no particular upper limit, but usually it is 4.5 g / cm 3 or less, preferably 4.3 g / cm 3 or less. In the present disclosure, the tap density is the powder packing density (tap density) g / cm when 5 to 10 g of the positive electrode active material powder is put into a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm. 3 It is determined as.

[0541] The median diameter d50 of the particles of the positive electrode active material (the secondary particle diameter when primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, still more preferably 0.8 μm or more, and most preferably 1.0 μm or more. Also, it is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. If it is below the above lower limit, it may be impossible to obtain a product with a high tap density. If it exceeds the upper limit, it takes time for lithium diffusion within the particles, which may cause a decrease in battery performance or problems such as streaks when preparing the positive electrode of the battery, that is, when slurrying the active material, conductive material, binder, etc. with a solvent and coating it in a thin film. Here, by mixing two or more types of the above positive electrode active materials having different median diameters d50, the filling property during positive electrode preparation can be further improved.

[0542] In the present disclosure, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When using LA-920 manufactured by HORIBA as the particle size distribution meter, as the dispersion medium used for measurement, an aqueous solution of 0.1 mass% sodium hexametaphosphate is used, and after ultrasonic dispersion for 5 minutes, the measurement refractive index 1.24 is set for measurement.

[0543] When primary particles aggregate to form secondary particles, the average primary particle diameter of the above positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.2 μm or more, and the upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. If it exceeds the above upper limit, it is difficult to form spherical secondary particles, which may adversely affect the powder filling property or significantly reduce the specific surface area, resulting in a high possibility of a decrease in battery performance such as output characteristics. Conversely, if it is below the above lower limit, problems such as poor reversibility of charge and discharge may occur because the crystal is usually underdeveloped.

[0544] In the present disclosure, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest value of the section formed by the left and right boundary lines of the primary particles with respect to a horizontal straight line is obtained for any 50 primary particles, and the average value is calculated to obtain the primary particle diameter.

[0545] The BET specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2 m 2 / g or more, still more preferably 0.3 m 2 / g or more, and the upper limit is preferably 50 m 2 / g or less, more preferably 40 m 2 / g or less, still more preferably 30 m 2 / g or less. If the BET specific surface area is smaller than this range, the battery performance is likely to deteriorate. If it is larger, it is difficult to increase the tap density, and problems may easily occur in the coatability during the formation of the positive electrode active material layer.

[0546] In the present disclosure, the BET specific surface area is defined as a value measured by the nitrogen adsorption BET one-point method by the gas flow method using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Otsuka Electronics Co., Ltd.). After preliminary drying the sample at 150 °C for 30 minutes under a nitrogen flow, a nitrogen-helium mixed gas is accurately adjusted so that the relative pressure value of nitrogen with respect to atmospheric pressure becomes 0.3, and the measurement is carried out using this gas.

[0547] When the lithium-ion secondary battery of the present disclosure is used as a large lithium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required. Therefore, it is preferable that the particles of the positive electrode active material are mainly secondary particles. The particles of the positive electrode active material preferably contain 0.5 to 7.0% by volume of fine particles having an average secondary particle diameter of 40 μm or less and an average primary particle diameter of 1 μm or less. By containing fine particles with an average primary particle diameter of 1 μm or less, the contact area with the electrolyte increases, and the diffusion of lithium ions between the electrode and the electrolyte can be made faster. As a result, the output performance of the battery can be improved.

[0548] As a method for manufacturing a positive electrode active material, a method general as a method for manufacturing an inorganic compound is used. In particular, although various methods are conceivable for creating a spherical or elliptical spherical active material, for example, a raw material substance of a transition metal is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to create and recover a spherical precursor, and this is dried if necessary, and then LiOH, Li 2 CO 3 , LiNO 3 and the like, and a method of adding an Li source such as and firing at a high temperature to obtain an active material can be mentioned.

[0549] For manufacturing the positive electrode, the above positive electrode active material may be used alone, or two or more kinds having different compositions may be used in combination in any combination or ratio. Preferred combinations in this case include LiCoO 2 and LiNi 0.33 Co 0.33 Mn 0.33 O 2 such as LiMn 2 O 4 or a combination with a substance in which a part of this Mn is substituted with another transition metal or the like, or a combination with LiCoO 2 or a substance in which a part of this Co is substituted with another transition metal or the like.

[0550] In terms of high battery capacity, the content of the above positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, more preferably 80 to 99% by mass. Further, 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, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0551] The above positive electrode mixture preferably further contains a binder, a thickener, and a conductive material. As the binder, any material can be used as long as it is safe for the solvents and electrolytes used during electrode manufacturing. For example, resin-based 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 copolymers or their hydrogenated products; thermoplastic elastomer-like polymers such as EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer or their hydrogenated products; 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; polymer compositions having ionic conductivity of alkali metal ions (especially lithium ions), etc. These may be used alone or in any combination and ratio of two or more.

[0552] The content of the binder, as the ratio of the binder in the positive electrode active material layer, is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and usually 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. If the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained, resulting in insufficient mechanical strength of the positive electrode and deterioration of 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.

[0553] Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, polyvinyl pyrrolidone, and salts thereof. It may be used alone or in any combination and ratio of two or more kinds.

[0554] The proportion 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 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If it is below this range, the coatability may be significantly reduced. If it exceeds this range, problems such as a decrease in the proportion of the active material in the positive electrode active material layer, a decrease in the battery capacity, and an increase in the resistance between the positive electrode active materials may occur.

[0555] As the conductive material, any known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel, graphite (graphite) such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, carbon materials such as needle coke, carbon nanotubes, fullerenes, and amorphous carbons such as VGCF. These may be used alone or in any combination and ratio of two or more kinds. The conductive material is usually used so as to contain 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and usually 50% by mass or less, preferably 30% by mass or less, 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.

[0556] As the solvent for forming the slurry, any solvent that can dissolve or disperse the positive electrode active material, conductive material, binder, and thickener used as necessary is not particularly limited in terms of its type, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous solvent include water, a mixed solvent of alcohol and water, and the like. Examples of the organic solvent 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), dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, and the like.

[0557] Examples of the material of the current collector for the positive electrode include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or metal materials such as alloys thereof; carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or its alloy, are preferred.

[0558] Examples of the shape of the current collector include, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, expanded metal, punched metal, foamed metal, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder, etc. Among these, a metal thin film is preferred. Note that the thin film may be formed in a mesh shape as appropriate. The thickness of the thin film is arbitrary, but 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, more preferably 50 μm or less. If the thin film is thinner than this range, the strength required for the current collector may be insufficient. Conversely, if the thin film is thicker than this range, the handleability may be impaired.

[0559] In addition, it is also preferable from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer that a conductive assistant is applied to the surface of the current collector. Examples of the conductive assistant include carbon and noble metals such as gold, platinum, and silver.

[0560] The ratio of the thickness of the current collector to that of the positive electrode active material layer is not particularly limited, but the value of (the thickness of the positive electrode active material layer on one side immediately before injecting the electrolytic solution) / (the thickness of the current collector) is preferably 20 or less, more preferably 15 or less, and most preferably 10 or less. Also, it is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heat during charge and discharge at a high current density. If it is below this range, the volume ratio of the current collector to the positive electrode active material increases, and the capacity of the battery may decrease.

[0561] The positive electrode can be manufactured by a conventional method. For example, a method can be mentioned in which the above-mentioned positive electrode active material, a binder, a thickener, a conductive material, a solvent, etc. are added to form a slurry-like positive electrode mixture, which is then applied to a current collector, dried, and pressed to increase the density.

[0562] The above-mentioned densification can be carried out by hand pressing, roller pressing, etc. The density of the positive electrode active material layer is preferably 1.5 g / cm 3 or more, more preferably 2 g / cm 3 or more, still more preferably 2.2 g / cm 3 or more, and preferably 5 g / cm 3 or less, more preferably 4.5 g / cm 3 or less, still more preferably 4 g / cm 3 or less. If it exceeds this range, the permeability of the electrolytic solution near the current collector / active material interface decreases, and in particular, the charge and discharge characteristics at a high current density deteriorate and high output may not be obtained. If it is below this range, the conductivity between the active materials decreases, the battery resistance increases, and high output may not be obtained.

[0563] When using the electrolyte of the present disclosure, from the viewpoint of enhancing the stability at high output and high temperature, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery exterior case. Specifically, it is preferably 15 times or more, and more preferably 40 times or more in terms of the area ratio of the total electrode area of the positive electrode to the surface area of the exterior of the secondary battery. The outer surface area of the battery exterior case means the total area obtained by calculation from the longitudinal, lateral, and thickness dimensions of the case portion filled with the power generation element excluding the protruding portion of the terminal in the case of a bottomed rectangular shape. In the case of a bottomed cylindrical shape, it is the geometric surface area approximated by regarding the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material. In a structure in which the positive electrode mixture layer is formed on both sides via a current collector foil, it means the sum of the areas calculated separately for each surface.

[0564] The thickness of the positive electrode plate is not particularly limited, but from the viewpoints of high capacity and high output, the thickness of the mixture layer after subtracting the metal foil thickness of the core material is preferably 10 μm or more, more preferably 20 μm or more, as the lower limit with respect to one side of the current collector, and is preferably 500 μm or less, more preferably 450 μm or less.

[0565] Also, a material having a composition different from this may be used on the surface of the positive electrode plate. Examples of the surface-attached substance 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.

[0566] <Negative electrode> The negative electrode is composed of a negative electrode active material layer containing a negative electrode active material and a current collector.

[0567] The negative electrode material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples include carbon materials, alloy-based materials, lithium-containing metal composite oxide materials, conductive polymers, and the like. These may be used alone or in any combination of two or more.

[0568] Examples of the negative electrode active material include pyrolysis products of organic substances under various pyrolysis conditions, carbonaceous materials capable of occluding and releasing lithium such as artificial graphite and natural graphite, metal oxide materials capable of occluding and releasing lithium such as tin oxide and silicon oxide, lithium metal, various lithium alloys, lithium-containing metal composite oxide materials, and the like. These negative electrode active materials may be used as a mixture of two or more.

[0569] As the carbonaceous material capable of occluding and releasing lithium, artificial graphite or purified natural graphite produced by high-temperature treatment of easily graphitizable pitch obtained from various raw materials, or those obtained by carbonizing after surface treatment of these graphites with pitch or other organic substances are preferred. Carbonaceous materials obtained by heat-treating natural graphite, artificial graphite, artificial carbonaceous substances, and artificial graphite-like substances at least once in the range of 400 to 3200 °C, carbonaceous materials in which the negative electrode active material layer is composed of at least two or more different crystalline carbonaceous materials and / or has an interface where different crystalline carbonaceous materials are in contact, and carbonaceous materials in which the negative electrode active material layer has an interface where at least two or more different orientation carbonaceous materials are in contact are more preferred in terms of a good balance between the initial irreversible capacity and the charge-discharge characteristics at a high current density. Also, these carbon materials may be used alone or in any combination and ratio of two or more.

[0570] Examples of the carbonaceous material obtained by heat-treating the above artificial carbonaceous material and artificial graphite material one or more times in the range of 400 to 3200 °C include coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch and those obtained by subjecting these pitches to oxidation treatment, needle coke, pitch coke and carbon agents obtained by partially graphitizing these, pyrolysis products of organic substances such as furnace black, acetylene black, pitch-based carbon fiber, carbonizable organic substances and their carbides, or solutions obtained by dissolving carbonizable organic substances in low-molecular-weight organic solvents such as benzene, toluene, xylene, quinoline, n-hexane and their carbides.

[0571] Examples of the metal material (excluding lithium titanium composite oxide) used as the negative electrode active material include, as long as it can occlude and release lithium, lithium alone, simple metals and alloys that form lithium alloys, or any of their compounds such as oxides, carbides, nitrides, silicides, sulfides or phosphides, and there is no particular limitation. The simple metals and alloys that form lithium alloys are preferably materials containing metal and metalloid elements of Groups 13 and 14, more preferably simple metals of aluminum, silicon and tin (hereinafter abbreviated as "specific metal elements") and alloys or compounds containing these atoms. These may be used alone or in combination of two or more in any combination and ratio.

[0572] Examples of the negative electrode active material having at least one atom selected from specific metal elements include simple metals of any one of the specific metal elements, alloys composed of two or more specific metal elements, alloys composed of one or two or more specific metal elements and one or two or more other metal elements, and compounds containing one or two or more specific metal elements, and composite compounds such as oxides, carbides, nitrides, silicides, sulfides or phosphides of these compounds. By using these simple metals, alloys or metal compounds as the negative electrode active material, it is possible to increase the capacity of the battery.

[0573] In addition, these composite compounds also include compounds in which several elements such as simple metals, alloys, or non-metallic elements are complexly bonded. Specifically, for example, in the case of silicon or tin, alloys of these elements with metals that do not act as negative electrodes can be used. For example, in the case of tin, complex compounds containing five to six elements in combinations of metals that act as negative electrodes other than tin and silicon, further metals that do not operate as negative electrodes, and non-metallic elements can also be used.

[0574] Specifically, simple Si, SiB 4 , SiB 6 , Mg 2 Si, Ni 2 Si, TiSi 2 , MoSi 2 , CoSi 2 , NiSi 2 , CaSi 2 , CrSi 2 , Cu 6 Si, FeSi 2 , MnSi 2 , NbSi 2 , TaSi 2 , VSi 2 , WSi 2 , ZnSi 2 , SiC, Si 3 N 4 , Si 2 N 2 , O, SiO v (0 < v ≦ 2), LiSiO or simple tin, SnSiO 3 , LiSnO, Mg 2 , Sn, SnO w (0 < w ≦ 2) can be mentioned. In addition, composite materials containing Si or Sn as the first constituent element and, in addition, second and third constituent elements are mentioned. The second constituent element is, for example, at least one of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, and zirconium. The third constituent element is, for example, at least one of boron, carbon, aluminum, and phosphorus. In particular, since high battery capacity and excellent battery characteristics can be obtained, as the above metal material, silicon or tin alone (which may contain trace amounts of impurities), SiO v (0 < v ≤ 2), SnO w (0 ≤ w ≤ 2), Si-Co-C composite material, Si-Ni-C composite material, Sn-Co-C composite material, Sn-Ni-C composite material are preferred.

[0575] The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium. However, from the viewpoint of high current density charge-discharge characteristics, a material containing titanium and lithium is preferred, and more preferably a lithium-containing composite metal oxide material containing titanium, and still more preferably a composite oxide of lithium and titanium (hereinafter abbreviated as "lithium titanium composite oxide"). That is, when a lithium titanium composite oxide having a spinel structure is contained and used as the negative electrode active material for an electrolytic solution battery, it is particularly preferred because the output resistance is greatly reduced.

[0576] As the above lithium titanium composite oxide, the general formula: Li x Ti y M z O 4 [wherein, 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 preferably a compound represented by. 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 The structure is particularly preferred because the balance of battery performance is good.

[0577] A particularly preferred representative composition of the above compound is Li in (i) 4 / 3 Ti 5 / 3 O 4 , and Li in (ii)1 Ti 2 O 4 In (iii), it is Li 4 / 5 Ti 11 / 5 O 4 In addition, for the structure where Z≠0, for example, Li 4 / 3 Ti 4 / 3 Al 1 / 3 O 4 is preferable.

[0578] It is preferable that the above negative electrode binder further contains a binder, a thickener, and a conductive material.

[0579] Examples of the above binder include the same ones as those that can be used for the positive electrode 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, and preferably 20% by mass or less, more preferably 15% by mass or less, still 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 ratio of the binder that does not contribute to the battery capacity increases, which may lead to a decrease in the battery capacity. On the other hand, if it is below the above range, the strength of the negative electrode may decrease.

[0580] In particular, when containing a rubber-like polymer represented by SBR as a 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, more preferably 2% by mass or less. Also, when containing a fluorine-based polymer represented by polyvinylidene fluoride as a main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less, more preferably 8% by mass or less.

[0581] Examples of the thickener include the same ones as those described above that can be used for the positive electrode. The proportion of the thickener with respect 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, more preferably 2% by mass or less. When the proportion of the thickener with respect to the negative electrode active material is below the above range, the coatability may be significantly reduced. When it exceeds the above range, the proportion of the negative electrode active material in the negative electrode active material layer may decrease, resulting in problems such as a decrease in the battery capacity and an increase in the resistance between the negative electrode active materials.

[0582] Examples of the conductive material for the negative electrode include metal materials such as copper and nickel; carbon materials such as graphite and carbon black.

[0583] The solvent for forming the slurry is not particularly limited in type as long as it can dissolve or disperse the negative electrode active material, the binder, and the thickener and the conductive material used as necessary, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, 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, hexane, and the like.

[0584] Examples of the material for the current collector for the negative electrode include copper, nickel, or stainless steel. Among them, copper foil is preferable from the viewpoints of being easy to process into a thin film and cost.

[0585] 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 capacity of the entire battery may decrease excessively. Conversely, if it is too thin, handling may become difficult.

[0586] The negative electrode can be manufactured by a conventional method. For example, a method can be mentioned in which the above-mentioned negative electrode material is mixed with a binder, thickener, conductive material, solvent, etc. to form a slurry, which is then applied to a current collector, dried, and pressed to increase density. When using an alloy material, a method of forming a thin film layer (negative electrode active material layer) containing the above-mentioned negative electrode active material by techniques such as vapor deposition, sputtering, or plating can also be used.

[0587] The electrode structure when the negative electrode active material is polarized is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g / cm 3 or more, more preferably 1.2 g / cm 3 or more, particularly preferably 1.3 g / cm 3 or more. Also, preferably 2.2 g / cm 3 or less, more preferably 2.1 g / cm 3 or less, even more preferably 2.0 g / cm 3 or less, particularly preferably 1.9 g / cm 3 or less. 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 deterioration of the charge-discharge characteristics at high current density due to a decrease in the permeability of the electrolyte near the current collector / negative electrode active material interface. If it is below the above range, the conductivity between the negative electrode active materials may decrease, the battery resistance may increase, and the capacity per unit volume may decrease.

[0588] The thickness of the negative electrode plate is designed according to the positive electrode plate to be used and is not particularly limited. However, the thickness of the mixture layer obtained by subtracting the thickness of the metal foil of the core material 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.

[0589] Alternatively, a material with a composition different from that of the negative electrode plate may be used on the surface of the negative electrode plate. Examples of the 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.

[0590] <Separator> The lithium-ion secondary battery of the present disclosure preferably further includes a separator. The material and shape of the separator are not particularly limited as long as they are stable in the electrolyte and have excellent liquid retention properties, and known ones can be used. Among them, resins, glass fibers, inorganic substances, etc., formed of materials stable to the electrolyte of the present disclosure are used, and it is preferable to use a porous sheet or a non-woven fabric-like form having excellent liquid retention properties.

[0591] As materials for the resin and glass fiber separators, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters, etc. can be used. These materials may be used alone or in any combination and ratio of two or more. Among them, the separator is preferably a porous sheet or non-woven fabric made of polyolefins such as polyethylene and polypropylene as raw materials in terms of good electrolyte permeability and shutdown effect.

[0592] The thickness of the separator is arbitrary, but it is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more. Also, it is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulation and mechanical strength may decrease. Also, 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 entire electrolyte battery may also decrease.

[0593] Furthermore, when using a porous material such as a porous sheet or non-woven fabric as the separator, the porosity of the separator is arbitrary, but it is usually 20% or more, preferably 35% or more, more preferably 45% or more. Also, it is usually 90% or less, preferably 85% or less, more preferably 75% or less. If the porosity is too small compared to the above range, the membrane resistance tends to increase and the rate characteristics deteriorate. Also, if it is too large compared to the above range, the mechanical strength and insulation of the separator tend to decrease.

[0594] Also, the average pore diameter of the separator is arbitrary, but it is usually 0.5 μm or less, preferably 0.2 μm or less. Also, it is usually 0.05 μm or more. If the average pore diameter exceeds the above range, short circuits are likely to occur. Also, if it is below the above range, the membrane resistance may increase and the rate characteristics may deteriorate.

[0595] On the other hand, as the inorganic material, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those in particle shape or fiber shape are used.

[0596] As the form, thin film-shaped materials such as non-woven fabrics, woven fabrics, and microporous films are used. Among thin film shapes, those with a pore diameter 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 shape, a separator formed by forming a composite porous layer containing the above inorganic particles on the surface layer of the positive electrode and / or negative electrode using a resin binder can be used. For example, alumina particles with a particle size of less than 1 μm in 90% of the positive electrode on both sides can be used to form a porous layer using a fluororesin as a binder.

[0597] <Battery Design> The electrode group may have either a laminated structure in which the above positive electrode plate and negative electrode plate are separated by the above separator, or a structure in which the above positive electrode plate and negative electrode plate are wound in a spiral shape with the above separator in between. 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.

[0598] If the electrode group occupancy rate is below the above range, the battery capacity will be small. On the other hand, if it exceeds the above range, the void space will be small, and when the battery gets hot, the members will expand, the vapor pressure of the liquid component of the electrolyte will increase, the internal pressure will rise, and the charge and discharge cycle performance and various characteristics such as high-temperature storage of the battery will deteriorate. Furthermore, the gas release valve for releasing the internal pressure to the outside may operate.

[0599] The current collector structure is not particularly limited, but in order to more effectively realize the improvement of the charge and discharge characteristics at a high current density with the electrolyte of the present disclosure, it is preferable to adopt a structure that reduces the resistance of the wiring part and the joint part. When the internal resistance is reduced in this way, the effect of using the electrolyte of the present disclosure is particularly well exhibited.

[0600] In the case where the electrode group has the above-described laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminal is preferably used. When the area of a single electrode becomes large, the internal resistance increases, so it is also preferably used to provide a plurality of terminals in the electrode to reduce the resistance. In the case where the electrode group has the above-described wound structure, a plurality of lead structures are provided for the positive electrode and the negative electrode respectively, and by bundling them to the terminal, the internal resistance can be lowered.

[0601] The material of the exterior case is not particularly limited as long as it is a substance stable to the electrolytic solution used. Specifically, metals such as nickel-plated steel sheets, stainless steels, aluminum or aluminum alloys, magnesium alloys, etc., or a laminated film (laminate film) of resin and aluminum foil is used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloys and laminate films are preferably used.

[0602] In the exterior case using metals, those having a sealed structure by welding metals to each other by laser welding, resistance welding, or ultrasonic welding, or those having a caulked structure using the above metals via a resin gasket can be mentioned. In the exterior case using the above laminate film, those having a sealed structure by heat-sealing resin layers to each other can be mentioned. In order to improve the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when heat-sealing the resin layer via the current collector terminal to form a sealed structure, since it becomes a junction of metal and resin, a resin having a polar group or a modified resin into which a polar group is introduced is preferably used as the interposed resin.

[0603] The shape of the lithium ion secondary battery of the present disclosure is arbitrary, and examples thereof include shapes such as cylindrical, rectangular, laminate, coin, and large-sized. Note that the shapes and configurations of the positive electrode, negative electrode, and separator can be changed and used according to the shape of each battery.

[0604] In addition, a lithium-ion secondary battery including a positive electrode, a negative electrode, and the above-described electrolytic solution, wherein the positive electrode includes a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material, and the positive electrode active material contains Mn, is also one of the preferred embodiments. Since the positive electrode active material layer includes a positive electrode active material containing Mn, the lithium-ion secondary battery is further excellent in high-temperature storage characteristics.

[0605] As the positive electrode active material containing Mn, LiMn 1.5 Ni 0.5 O 4 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 is preferred.

[0606] In addition, as the positive electrode active material containing Mn, LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 is preferred.

[0607] 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, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the capacitance may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0608] The positive electrode active material layer may further include a conductive material, a thickener, and a binder.

[0609] As the above binder, any material can be used as long as it is safe for the solvent and electrolyte used during electrode manufacturing. For example, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, NBR (acrylonitrile-butadiene rubber), fluororubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer or its hydrogenated product, EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-ethylene copolymer, styrene-isoprene-styrene block copolymer or its hydrogenated product, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, propylene-α-olefin copolymer, fluorinated polyvinylidene fluoride, tetrafluoroethylene-ethylene copolymer, polymer compositions having ionic conductivity of alkali metal ions (especially lithium ions), etc. may be mentioned. These substances may be used alone or in combination of two or more in any combination and ratio.

[0610] The content of the binder, as the ratio of the binder in the positive electrode active material layer, is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and usually 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. If the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained, resulting in insufficient mechanical strength of the positive electrode and deterioration of 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.

[0611] Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. It may be used alone or in combination of two or more in any combination and ratio.

[0612] 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 is usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If it is below this range, the coatability may be significantly reduced. If it exceeds this range, problems such as a decrease in the ratio of the active material in the positive electrode active material layer and a decrease in the battery capacity, or an increase in the resistance between the positive electrode active materials may occur.

[0613] As the conductive material, any known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel, graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, and carbon materials such as amorphous carbon such as needle coke. These may be used alone or in combination of two or more in any combination and ratio. The conductive material is usually used 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 is usually 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less in the positive electrode active material layer. 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.

[0614] Since the high-temperature storage characteristics of the positive electrode current collector are further improved, it is preferably composed of a valve metal or an alloy thereof. Examples of the valve metal include aluminum, titanium, tantalum, and chromium. It is more preferable that the positive electrode current collector is composed of aluminum or an alloy of aluminum.

[0615] Since the high-temperature storage characteristics of the above lithium-ion secondary battery are further improved, it is preferable that the portion in contact with the electrolytic solution among the portions electrically connected to the above positive electrode current collector is also made of valve metal or its alloy. In particular, it is preferable that the battery exterior case and the portions of the lead wires, safety valves, etc. housed in the above battery exterior case that are electrically connected to the positive electrode current collector and are in contact with the non-aqueous electrolytic solution are made of valve metal or its alloy. Stainless steel coated with valve metal or its alloy may be used.

[0616] The manufacturing method of the above positive electrode is as described above. For example, a binder, thickener, conductive material, solvent, etc. described above are added to the above positive electrode active material to form a slurry-like positive electrode mixture, which is applied to the above positive electrode current collector, dried, and then pressed to increase the density.

[0617] The configuration of the above negative electrode is as described above.

[0618] A module including the lithium-ion secondary battery of the present disclosure is also one of the present disclosures.

[0619] The above electric double layer capacitor may include a positive electrode, a negative electrode, and the above electrolytic solution. In the above electric double layer capacitor, at least one of the positive electrode and the negative electrode is a polarizable electrode, and the following electrodes described in detail in JP-A-9-7896 can be used as the polarizable electrode and the non-polarizable electrode.

[0620] The polarizable electrode mainly composed of activated carbon used in the present disclosure preferably contains non-activated carbon with a large specific surface area and a conductive agent such as carbon black that imparts electron conductivity. The polarizable electrode can be formed by various methods. For example, activated carbon powder, carbon black, and phenolic resin are mixed, and after press molding, it is fired and activated in an inert gas atmosphere and a steam atmosphere to form a polarizable electrode composed of activated carbon and carbon black. Preferably, this polarizable electrode is joined with a current collector, a conductive adhesive, etc.

[0621] Alternatively, activated carbon powder, carbon black, and a binder can be kneaded in the presence of alcohol, formed into a sheet, and dried to obtain a polarizable electrode. For example, polytetrafluoroethylene is used as this binder. Further, activated carbon powder, carbon black, a binder, and a solvent can be mixed to form a slurry, and this slurry can be coated on a metal foil of a current collector and dried to obtain a polarizable electrode integrated with the current collector.

[0622] A double-layer capacitor may be formed using polarizable electrodes mainly composed of activated carbon at both electrodes. However, a configuration using a non-polarizable electrode on one side, for example, a configuration combining a positive electrode mainly composed of a battery active material such as a metal oxide and a negative electrode of a polarizable electrode mainly composed of activated carbon, a negative electrode mainly composed of a carbon material capable of reversibly occluding and releasing lithium ions, or a negative electrode of lithium metal or a lithium alloy and a polarizable positive electrode mainly composed of activated carbon is also possible.

[0623] Alternatively, instead of or in combination with activated carbon, carbonaceous materials such as carbon black, graphite, expanded graphite, porous carbon, carbon nanotubes, carbon nanohorns, and ketjen black may be used.

[0624] The non-polarizable electrode is preferably mainly composed of a carbon material capable of reversibly occluding and releasing lithium ions, and a material obtained by occluding lithium ions in this carbon material is used for the electrode. In this case, a lithium salt is used as the electrolyte. According to the double-layer capacitor having this configuration, a breakdown voltage exceeding 4 V can be obtained.

[0625] The solvent used for preparing the slurry in the production of the electrode preferably dissolves the binder, and N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, dimethyl phthalate, ethanol, methanol, butanol, or water is appropriately selected according to the type of the binder.

[0626] Examples of the activated carbon used for the non-polar electrode include phenol resin-based activated carbon, coconut shell-based activated carbon, petroleum coke-based activated carbon, etc. Among these, it is preferable to use petroleum coke-based activated carbon or phenol resin-based activated carbon in terms of obtaining a large capacity. Further, examples of the activation treatment method of the activated carbon include a steam activation treatment method, a molten KOH activation treatment method, etc., and it is preferable to use the activated carbon by the molten KOH activation treatment method in terms of obtaining a larger capacity.

[0627] Preferable conductive agents used for the non-polar electrode include carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, metal fiber, conductive titanium oxide, ruthenium oxide. The mixing amount of the conductive agent such as carbon black used for the non-polar electrode is preferably 1 to 50% by mass in the total amount with the activated carbon so as to obtain good conductivity (low internal resistance), and if it is too much, the capacity of the product will decrease.

[0628] Further, as the activated carbon used for the non-polar electrode, in order to obtain an electric double layer capacitor with a large capacity and a low internal resistance, it is preferable to use activated carbon with an average particle size of 20 μm or less and a specific surface area of 1500 to 3000 m 2 / g. Further, preferable carbon materials for constituting an electrode mainly composed of a carbon material capable of reversibly occluding and releasing lithium ions include natural graphite, artificial graphite, graphitized mesocarbon microspheres, graphitized whiskers, gas-phase grown carbon fibers, calcined products of furfuryl alcohol resins, or calcined products of novolak resins.

[0629] The current collector may be any one that is chemically and electrochemically corrosion-resistant. As the current collector for the non-polar electrode mainly composed of activated carbon, stainless steel, aluminum, titanium, or tantalum can be preferably used. Among these, stainless steel or aluminum is a particularly preferable material in terms of both the characteristics and price of the obtained electric double layer capacitor. As the current collector for the electrode mainly composed of a carbon material capable of reversibly occluding and releasing lithium ions, preferably stainless steel, copper, or nickel is used.

[0630] In addition, in order to previously occlude lithium ions in a carbon material capable of reversibly occluding and releasing lithium ions, there are the following methods: (1) a method of mixing powdery lithium with a carbon material capable of reversibly occluding and releasing lithium ions; (2) placing a lithium foil on an electrode formed of a carbon material capable of reversibly occluding and releasing lithium ions and a binder, immersing this electrode in an electrolytic solution in which a lithium salt is dissolved in a state of being in electrical contact with the electrode to ionize lithium, and incorporating lithium ions into the carbon material; and (3) placing an electrode formed of a carbon material capable of reversibly occluding and releasing lithium ions and a binder on the negative side, placing lithium metal on the positive side, immersing them in a non-aqueous electrolytic solution using a lithium salt as an electrolyte, and passing an electric current to electrochemically incorporate lithium in an ionized state into the carbon material.

[0631] As electric double layer capacitors, wound type electric double layer capacitors, laminated type electric double layer capacitors, coin type electric double layer capacitors, etc. are generally known, and the above electric double layer capacitors can also be of these forms.

[0632] For example, a wound type electric double layer capacitor is assembled by winding a positive electrode and a negative electrode each composed of a laminate of a current collector and an electrode layer (electrode) via a separator to produce a wound element, placing this wound element in a case made of aluminum or the like, filling it with an electrolytic solution, preferably a non-aqueous electrolytic solution, and then sealing it with a rubber sealing body.

[0633] As the separator, those having a conventionally known material and configuration can be used. For example, a polyethylene porous membrane, polytetrafluoroethylene, polypropylene fibers, glass fibers, a non-woven fabric of cellulose fibers, etc. can be mentioned.

[0634] In addition, by a known method, it is also possible to form a laminated type electric double layer capacitor in which sheet-like positive and negative electrodes are laminated via an electrolytic solution and a separator, or a coin type electric double layer capacitor in which the positive and negative electrodes are configured in a coin shape by fixing with a gasket via an electrolytic solution and a separator.

[0635] The electrolyte of the present disclosure is useful as an electrolyte for large lithium-ion secondary batteries for hybrid vehicles, distributed power sources, and electric double layer capacitors.

Examples

[0636] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to such examples only.

[0637] Synthesis Example 1 Under an argon stream, 1-Methyl tetrahydrothiophenium iodide and methanol were charged into a reaction vessel and stirred at room temperature. After confirming that 1-Methyl tetrahydrothiophenium iodide was completely dissolved, silver oxide was added in an amount of 0.8 equivalent to 1-Methyl tetrahydrothiophenium iodide and stirred at room temperature. After filtering off the precipitate (silver iodide), the filtrate was concentrated to obtain a methanol solution of 1-Methyl tetrahydrothiophenium hydroxide.

[0638] Boric acid and dehydrated methanol were charged into a reaction vessel and stirred at room temperature. After confirming that boric acid was completely dissolved, the solution obtained above was gradually added dropwise so that the amount of 1-Methyl tetrahydrothiophenium hydroxide became equal. Next, oxalic acid was added to a 2-equivalent amount and stirred at room temperature. After stirring, the solvent was distilled off under reduced pressure (using an evaporator) to obtain a crude product. Then, recrystallization was performed using dehydrated methanol to obtain the target compound (I-1) represented by the following formula. The fact that it was the target product was confirmed by NMR analysis ( 1 H, 13 C, 11 B).

Chemical formula

[0639] Synthesis Example 2 Under an argon stream, 1-Methylhexahydorothipyrilium iodide and methanol were charged into a reaction vessel and stirred at room temperature. After confirming that 1-Methylhexahydorothipyrilium iodide was completely dissolved, 0.8 equivalent of silver oxide was added to 1-Methylhexahydorothipyrilium iodide and stirred at room temperature. After filtering off the precipitate (silver iodide), the filtrate was concentrated to obtain a methanol solution of 1-Methylhexahydrothipyryrilium hydroxide.

[0640] Boric acid and dehydrated methanol were charged into a reaction vessel and stirred at room temperature. After confirming that boric acid was completely dissolved, the solution obtained above was gradually added dropwise so that the amount of 1-Methylhexahydrothipyryrilium hydroxide became equal. Then, 2 equivalents of oxalic acid were added and stirred at room temperature. After stirring, the solvent was distilled off under reduced pressure (using an evaporator) to obtain a crude product. Thereafter, recrystallization was performed using dehydrated methanol to obtain the target compound (I-2) represented by the following formula. That it was the target product was confirmed by NMR analysis ( 1 H, 13 C, 11 B).

Chemical formula

[0641] Synthesis Example 3 Under an argon stream, 1-Methy-thiocanium iodide and methanol were charged into a reaction vessel and stirred at room temperature. After confirming that 1-Methy-thiocanium iodide was completely dissolved, 0.8 equivalent of silver oxide was added to 1-Methy-thiocanium iodide and stirred at room temperature. After filtering off the precipitate (silver iodide), the filtrate was concentrated to obtain a methanol solution of 1-Methy-thiocanium hydroxide.

[0642] Boric acid and dehydrated methanol were charged into a reaction vessel and stirred at room temperature. After confirming that the boric acid was completely dissolved, the solution obtained above was gradually added dropwise so that the amount of 1-Methy-thiocanium hydroxide became equal. Next, oxalic acid was added to a 2-equivalent amount and stirred at room temperature. After stirring, the solvent was distilled off under reduced pressure (using an evaporator) to obtain a crude product. Thereafter, recrystallization was performed using dehydrated methanol to obtain the target compound (I-3) represented by the following formula. The fact that it was the target product was confirmed by NMR analysis ( 1 H, 13 C, 11 B).

Chemical formula

[0643] Synthesis Example 4 <Synthesis of Lithium Diethylsulfamate> Lithium chloride (3.0 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise thereto. After stirring this solution at 80 °C for 1 hour, it was cooled and returned to room temperature, and a mixed solution of diethylamine (6.2 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice-water bath (the reaction solution temperature rose by 5 - 10 °C, and the dropping time was 5 - 10 minutes). After stirring this solution at room temperature for 1 hour, it was filtered and washed with dichloromethane to obtain the target crude lithium diethylsulfamate (9.1 g). The obtained crude lithium diethylsulfamate (2.0 g) was dissolved in 7 mL of methanol at 60 °C, 7 mL of dimethyl carbonate was added thereto, and it was concentrated under reduced pressure until the volume became half. Again, 7 mL of dimethyl carbonate was added and concentrated under reduced pressure. When a solid precipitated, the concentration under reduced pressure was stopped, filtered, and washed with dimethyl carbonate to obtain the target lithium diethylsulfamate (0.9 g, 6 mmol, total yield 38%).

Chemical formula

[0644] Synthesis Example 5 <Synthesis of Lithium Bis(2,2,2-trifluoroethyl)sulfamate> Lithium chloride (1.0 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise thereto. After stirring this solution at 80 °C for 1 hour, it was cooled and returned to room temperature, and bis(2,2,2-trifluoroethyl)amine (10.3 g, 57 mmol) was added dropwise under an ice-water bath (the temperature of the reaction solution increased by 0 to 5 °C, and the dropping time was about 5 minutes). After stirring this solution at room temperature for 1 hour, triethylamine (6.0 g) and dichloromethane (50 mL) were added and stirred for another day. The resulting reaction mixture was filtered and washed with dichloromethane to obtain the target lithium bis(2,2,2-trifluoroethyl)sulfamate (3.4 g, 13 mmol, total yield 54%). [Chemical formula]

[0645] Synthesis Example 6 <Synthesis of Lithium Methyl 2,2,2-trifluoroethylsulfamate> Lithium chloride (1.0 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise thereto. After stirring this solution at 80 °C for 1 hour, it was cooled and returned to room temperature, and methyl 2,2,2-trifluoroethylamine (6.4 g, 57 mmol) was added dropwise under an ice-water bath (the temperature of the reaction solution increased by 0 to 5 °C, and the dropping time was about 5 minutes). After stirring this solution at room temperature for 1 hour, triethylamine (6.0 g) and dichloromethane (50 mL) were added and stirred for another day. The resulting reaction mixture was filtered and washed with dichloromethane to obtain the target lithium methyl 2,2,2-trifluoroethylsulfamate (2.3 g, 12 mmol, total yield 49%). [Chemical formula]

[0646] Synthesis Example 7 <Synthesis of Lithium Bis(cyanomethyl)sulfamate> Lithium chloride (1.0 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise thereto. After stirring this solution at 80 °C for 1 hour, it was cooled and returned to room temperature, and a mixed solution in which bis(cyanomethyl)amine (5.4 g, 57 mmol) was dissolved in acetonitrile (30 mL) was added dropwise under an ice-water bath (the temperature of the reaction solution increased by 5 - 10 °C, and the dropping time was 5 - 10 minutes). After stirring this solution at room temperature for 1 hour, triethylamine (6.0 g) and dichloromethane (50 mL) were added and stirred for another day. The obtained reaction mixture was filtered and washed with dichloromethane to obtain the target lithium bis(cyanomethyl)sulfamate (3.9 g, 22 mmol, total yield 91%). [Chemical formula]

[0647] (Preparation of electrolyte solution) Examples 1 - 59 and Comparative Examples 1 - 4 Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed so that the volume ratio was 30 / 40 / 30, and LiPF 6 was added to this mixture to a concentration of 1.0 mol / L to obtain a basic electrolyte solution. Further, each additive described in Tables 1 - 3 was added to this basic electrolyte solution to the concentrations described in Tables 1 - 3 to obtain a non-aqueous electrolyte solution.

[0648] (Fabrication of aluminum laminate type lithium ion secondary battery) [Fabrication of positive electrode] LiNi as a positive electrode active material 0.6 Co 0.2 Mn 0.2 O 2(NMC) 93 mass %, 3 mass % of acetylene black as a conductive material, and 4 mass % of polyvinylidene fluoride (PVdF) as a binder were mixed in an N-methylpyrrolidone solvent to form a slurry. The obtained slurry was applied to one side of a 15-μm-thick aluminum foil pre-coated with a conductive aid, dried, and roll-pressed with a press machine. It was cut into a shape with a size of the active material layer of 50 mm in width, 30 mm in length, and an uncoated portion of 5 mm in width and 9 mm in length to obtain a positive electrode.

[0649] [Fabrication of Negative Electrode] To 98 parts by mass of a carbonaceous material (graphite), 1 part by mass of an aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose: 1 mass %) and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50 mass %) as a thickening agent and a binder were added, and the mixture was mixed with a disperser to form a slurry. The obtained slurry was applied to a 10-μm-thick copper foil, dried, and rolled with a press machine. It was cut into a shape with a size of the active material layer of 52 mm in width, 32 mm in length, and an uncoated portion of 5 mm in width and 9 mm in length to obtain a negative electrode.

[0650] [Fabrication of Aluminum Laminate Cell] The above positive electrode and the negative electrode were opposed to each other with a 20-μm-thick microporous polyethylene film (separator) in between, the non-aqueous electrolyte obtained above was injected, and after the non-aqueous electrolyte sufficiently penetrated the separator and the like, it was sealed and pre-charged and aged to fabricate a lithium-ion secondary battery.

[0651] (Measurement of Battery Characteristics) [Cycle Characteristics Test] The lithium-ion secondary battery manufactured as described above was charged at a constant current-constant voltage up to 4.2 V at a current corresponding to 1C (hereinafter referred to as CC / CV charging) (0.1C cut) at 25°C while being sandwiched and pressed between plates, and then discharged at a constant current of 1C down to 3V. This was regarded as one cycle, and the initial discharge capacity was determined from the discharge capacity of the third cycle. Here, 1C represents the current value for discharging the reference capacity of the battery in one hour. For example, 0.2C represents a current value that is one-fifth of that. The cycle was performed again, and the discharge capacity after 200 cycles was measured. The ratio of the discharge capacity after 200 cycles to the initial discharge capacity was determined and taken as the cycle capacity retention rate (%). (Discharge capacity after 200 cycles) ÷ (Initial discharge capacity) × 100 = Capacity retention rate (%) The results calculated with the value of Comparative Example 1 taken as 1 are shown in Tables 1 to 3.

[0652] [Evaluation of IV resistance] The battery for which the evaluation of the initial discharge capacity had been completed was charged at 25°C at a constant current of 1C to a capacity that was half of the initial discharge capacity. This was discharged at 1.0C, and the voltage at 10 seconds was measured. The resistance was calculated from the voltage drop during discharge and taken as the IV resistance. The results calculated with the value of Comparative Example 1 taken as 1 are shown in Tables 1 to 3.

[0653]

Table 1

[0654]

Table 2

[0655]

Table 3

[0656] The abbreviations in the table are as follows. (I-1):

Chemical formula

Chem.

Chem.

Chem.

Chem.

Chem.

Claims

1. The following general formula (1): 【Chemistry 1】 (In general formula (1), R １０１ is a group represented by -(CY 1 Y 2 ) n - (Y 1 and Y 2 are hydrogen atoms, and n is an integer of 4 to 7). １０２ is a methyl group or an ethyl group.

2. The electrolyte according to claim 1, wherein the content of the compound (1) is 0.001 to 10% by mass relative to the electrolyte.

3. The following general formula (1-1): 【Chemistry 2】 (In general formula (1-1), R １０１ is a group represented by -(CY 1 Y 2 ) n - (Y 1 and Y 2 are hydrogen atoms, and n is an integer of 4 to 7). １０２ is a methyl group or an ethyl group), and a bis(oxalato)borate anion.

4. An electrochemical device comprising the electrolyte solution according to any one of claims 1 to 3.

5. A lithium ion secondary battery comprising the electrolyte solution according to any one of claims 1 to 3.

6. A module comprising the electrochemical device according to claim 4 or the lithium ion secondary battery according to claim 5.

7. The following general formula (1): 【Chemistry 3】 (In general formula (1), R １０１ is a group represented by -(CY 1 Y 2 ) n - (Y 1 and Y 2 are hydrogen atoms, and n is an integer of 4 to 7). １０２ is a methyl group or an ethyl group.

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