An electrolytic solution for an electrochemical device a solvent, an ionic substance, and an additive agent, the additive agent containing α-methyl-γ-butyrolactone and δ-valerolactone.

The present invention provides a nonaqueous electrolytic solution capable of improving electrochemical characteristics in the case of using an energy storage device at a high temperature and at a high voltage and further capable of inhibiting the gas generation while maintaining a capacity retention rate after storage at a high temperature and at a high voltage and also provides an energy storage device using the same. Disclosed is a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the nonaqueous electrolytic solution containing a carboxylic acid ester compound represented by the following general formula (I). ##STR00001## In the formula, each of R.sup.1 and R.sup.2 independently represents a hydrogen atom, a —C(═O)—OR.sup.4 group, or the like, and R.sup.1 and R.sup.2 may be bonded to each other to form a ring structure. R.sup.3 represents a hydrogen atom or the like, and n represents an integer of 1 to 3. When n is 1, then L and R.sup.4 represent an alkyl group having 1 to 6 carbon atoms or the like; and when n is 2 or 3, then L represents an n-valent connecting group, X represents a —C(═O)— group, an —S(═O)— group, an —S(═O).sub.2— group, an —S(═O).sub.2—R.sup.5—S(═O).sub.2— group or a CR.sup.6R.sup.7 group, R.sup.5 represents an alkylene group having 1 to 4 carbon atoms, and each of R.sup.6 and R.sup.7 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

The present invention provides a nonaqueous electrolytic solution capable of improving electrochemical characteristics in the case of using an energy storage device at a high temperature and at a high voltage and further capable of inhibiting the gas generation while maintaining a capacity retention rate after storage at a high temperature and at a high voltage and also provides an energy storage device using the same. Disclosed is a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the nonaqueous electrolytic solution containing a carboxylic acid ester compound represented by the following general formula (I). ##STR00001## In the formula, each of R.sup.1 and R.sup.2 independently represents a hydrogen atom, a —C(═O)—OR.sup.4 group, or the like, and R.sup.1 and R.sup.2 may be bonded to each other to form a ring structure. R.sup.3 represents a hydrogen atom or the like, and n represents an integer of 1 to 3. When n is 1, then L and R.sup.4 represent an alkyl group having 1 to 6 carbon atoms or the like; and when n is 2 or 3, then L represents an n-valent connecting group, X represents a —C(═O)— group, an —S(═O)— group, an —S(═O).sub.2— group, an —S(═O).sub.2—R.sup.5—S(═O).sub.2— group or a CR.sup.6R.sup.7 group, R.sup.5 represents an alkylene group having 1 to 4 carbon atoms, and each of R.sup.6 and R.sup.7 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

An electrolytic solution comprising N-(fluorosulfonyl)-N-(fluoroalkylsulfonyl)imide or di(fluorosulfonyl)imide, from which a residual solvent that affects the properties of the electrolyte solution material is reduced, is provided. A method for producing an electrolyte solution material containing fluorosulfonyl imide salt represented by the following general formula (1) and an electrolyte solution preparation solvent comprises decompressing and/or heating a solution containing the fluorosulfonyl imide salt and the electrolyte solution preparation solvent to volatilize a production solvent for the fluorosulfonyl imide salt. ##STR00001## In general formula (1), R.sub.1 represents a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms, R.sub.2 represents an alkali metal ion.

A non-aqueous lithium power storage element that includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, the positive electrode having a positive electrode collector and a positive electrode active material layer that includes active carbon, and the non-aqueous lithium power storage element having configuration (1) and/or (2). (1) The negative electrode includes a negative electrode collector and a negative electrode active material layer (2) The non-aqueous electrolyte contains (A) LiPF.sub.6 and/or LiBF.sub.4, (B) an imide lithium salt, and (C) an oxalate-complex lithium salt, the ratio of the mass of component (C) to the total mass of components (A) and (B) being 1.0-10.0 mass %.

An electrolyte including a dinitrile compound, a trinitrile compound, and propyl propionate. Based on the total weight of the electrolyte, the content X of the nitrile compound and the content Y of the trinitrile compound meet the conditions represented by Formula (1) and Formula (2): {about 2 wt %≤(X+Y)≤about 11 wt % . . . (1), about 0.1≤(X/Y)≤about 8 . . . (2)}. The electrolyte further includes at least one selected from the group consisting of a cyclic carbonate ester having a carbon-carbon double bond, a fluorinated chain carbonate ester, a fluorinated cyclic carbonate ester, and a compound having a sulfur-oxygen double bond. The electrolyte is capable of effectively inhibiting the increase in DC internal resistance of an electrochemical device so that the electrochemical device has excellent cycle and storage performance.

An electrolyte solution containing at least one selected from a compound represented by the following formula (1-1) (wherein Rf.sup.111s are the same as or different from each other and are each a C2-C4 fluorinated alkenyl group), a compound represented by the following formula (1-2) (wherein R.sup.121 is a C1-C4 alkyl group; and Rf.sup.121 is a C2-C4 fluorinated alkenyl group), and a compound represented by the following formula (1-3) (wherein Rf.sup.131 is a C1-C3 fluorinated alkyl group; and R.sup.131 is a C6-C12 aryl group): ##STR00001##

An electrochemical device, which is a non-aqueous electrochemical device, comprising a polymer (P) enclosed in an inside of the electrochemical device, wherein the polymer (P) is a polymer having a molecular structure containing a unit (P) represented by the following formula (P), the polymer (P) having a weight-average molecular weight of greater than 50,000, as well as an electrode for an electrochemical device, a coating liquid for an electrochemical device, an insulating layer for an electrochemical device, an undercoat layer for an electrochemical device, and an electrolytic solution for an electrochemical device including the polymer (P) and other ingredients:

##STR00001## in the formula (P), R.sup.P is a group of 1 to 20 carbon atoms.

An electrochemical device, which is a non-aqueous electrochemical device, comprising a polymer (P) enclosed in an inside of the electrochemical device, wherein the polymer (P) is a polymer having a molecular structure containing a unit (P) represented by the following formula (P), the polymer (P) having a weight-average molecular weight of greater than 50,000, as well as an electrode for an electrochemical device, a coating liquid for an electrochemical device, an insulating layer for an electrochemical device, an undercoat layer for an electrochemical device, and an electrolytic solution for an electrochemical device including the polymer (P) and other ingredients:

##STR00001## in the formula (P), R.sup.P is a group of 1 to 20 carbon atoms.

The present invention provides a non-aqueous electrolytic solution which can be handled industrially stably, and which allows for achieving a good durability performance, particularly, a good capacity retention rate during repeated charging and discharging, of an energy device typified by a non-aqueous electrolytic solution secondary battery. The non-aqueous electrolytic solution contains a compound(s) represented by the following general formula(e) (A1) and/or (A2). In formula (A1), X.sup.1 represents a halogen atom; each of R.sup.1, R.sup.2, R.sup.5 and R.sup.6 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; and each of R.sup.3 and R.sup.4 independently represents a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.1 to R.sup.6 may be bonded to each other to form a ring. In formula (A2), each of X.sup.2 and X.sup.3 independently represents a halogen atom; and each of R.sup.7 to R.sup.14 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.7 to R.sup.14 may be bonded to each other to form a ring.

##STR00001##