Electrolytes and electrolyte additives for energy storage devices comprising a silicon compound are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte, and at least one electrolyte additive selected from a silicon compound.

Electrolytes and electrolyte additives for energy storage devices comprising a silicon compound are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte, and at least one electrolyte additive selected from a silicon compound.

An electrolyte solution containing at least one compound represented by formula (1-1) and formula (1-2), formula (1-1) being:

##STR00001##

where R.sup.101 is an optionally fluorinated C1-C7 alkyl group, an optionally fluorinated C2-C8 alkenyl group, an optionally fluorinated C2-C9 alkynyl group, or an optionally fluorinated C6-C12 aryl group, and optionally contains at least one selected from O, Si, S, and N in a structure; and formula (1-2) being:

##STR00002##

where R.sup.102 and R.sup.103 are (i) each individually H, F, an optionally fluorinated C1-C7 alkyl group, an optionally fluorinated C2-C7 alkenyl group, an optionally fluorinated C2-C9 alkynyl group, or an optionally fluorinated C5-C12 aryl group, or (ii) hydrocarbon groups binding to each other to form a 5-membered or 6-membered hetero ring with a nitrogen atom; and R.sup.102 and R.sup.103 each optionally contain at least one selected from O, S, and N in a structure.

An electrolyte solution for a lithium ion secondary battery containing at least one compound (1) selected from compounds represented by formulas (1A) and (1B):

##STR00001##

wherein R.sup.101 and R.sup.102, each independently, are a C5-C10 organic group, optionally contain at least one selected from a hetero atom and an unsaturated bond, and optionally contain a ring,

##STR00002##

wherein R.sup.103 to R.sup.105, each independently, are a C1-C10 organic group, optionally contain at least one selected from the group consisting of a hetero atom and an unsaturated bond, and optionally contain a ring.

An electrolyte solution containing a compound (1) represented by the formula (1):

##STR00001##

wherein R.sup.1 and R.sup.2 are each independently a C1-C4 alkyl group optionally containing an ether bond; and a compound (11) represented by the formula (11):

##STR00002##

wherein R.sup.101 and R.sup.102 are each independently a substituent that is a C1-C7 alkyl group or the like. The substituent optionally contains one or more divalent to hexavalent hetero atoms in its structure, with one or more hydrogen atoms each optionally replaced by a fluorine atom or a C0-C7 functional group. Also disclosed is an electrochemical device containing the electrolyte solution, a lithium ion secondary battery containing the electrolyte solution, and a module including the electrochemical device or the lithium ion secondary battery.

An electrolyte solution applicable to high-voltage electrochemical devices and capable of improving the cycle characteristics of electrochemical devices even at high voltage, and an electrochemical device. The electrolyte solution contains a fluorinated diether and a metal salt having a specific structure. The fluorinated diether is represented by CFR.sup.11R.sup.12—O—CH.sub.2CH.sub.2—O—R.sup.13, wherein R.sup.11 and R.sup.12 are each individually H, CH.sub.3, F, CH.sub.2F, CHF.sub.2, or CF.sub.3; and R.sup.13 is a C1 or C2 non-fluorinated alkyl group or a C1 or C2 fluorinated alkyl group.

An electrolyte solution applicable to high-voltage electrochemical devices and capable of improving the cycle characteristics of electrochemical devices even at high voltage, and an electrochemical device. The electrolyte solution contains a fluorinated diether and a metal salt having a specific structure. The fluorinated diether is represented by CFR.sup.11R.sup.12—O—CH.sub.2CH.sub.2—O—R.sup.13, wherein R.sup.11 and R.sup.12 are each individually H, CH.sub.3, F, CH.sub.2F, CHF.sub.2, or CF.sub.3; and R.sup.13 is a C1 or C2 non-fluorinated alkyl group or a C1 or C2 fluorinated alkyl group.

Provided are a nonaqueous electrolyte capable of providing a nonaqueous electrolyte energy storage device with reduced direct current resistance and an increased capacity retention ratio after charge-discharge cycles, a nonaqueous electrolyte energy storage device including such a nonaqueous electrolyte, and a method for producing such a nonaqueous electrolyte energy storage device. One mode of the present invention is a nonaqueous electrolyte for an energy storage device, containing an additive represented by the following Formula (1) or Formula (2). In Formula (1), R.sup.1 to R.sup.4 are each independently a hydrogen atom or a group represented by —NR.sup.a.sub.2, —OR.sup.a, —SR.sup.a, etc., with the proviso that at least one of R.sup.1 to R.sup.4 is a group represented by —OR.sup.a, —SR.sup.a, —COOR.sup.a, —COR.sup.a, —SO.sub.2R.sup.a, or —SO.sub.3R.sup.a. In Formula (2), R.sup.5 to R.sup.7 are each independently a hydrogen atom or a group represented by —NR.sup.b.sub.2, —OR.sup.b, or —SR.sup.b, with the proviso that at least one of R.sup.5 to R.sup.7 is a group represented by —SR.sup.b.

##STR00001##

Provided are a nonaqueous electrolyte capable of providing a nonaqueous electrolyte energy storage device with reduced direct current resistance and an increased capacity retention ratio after charge-discharge cycles, a nonaqueous electrolyte energy storage device including such a nonaqueous electrolyte, and a method for producing such a nonaqueous electrolyte energy storage device. One mode of the present invention is a nonaqueous electrolyte for an energy storage device, containing an additive represented by the following Formula (1) or Formula (2). In Formula (1), R.sup.1 to R.sup.4 are each independently a hydrogen atom or a group represented by —NR.sup.a.sub.2, —OR.sup.a, —SR.sup.a, etc., with the proviso that at least one of R.sup.1 to R.sup.4 is a group represented by —OR.sup.a, —SR.sup.a, —COOR.sup.a, —COR.sup.a, —SO.sub.2R.sup.a, or —SO.sub.3R.sup.a. In Formula (2), R.sup.5 to R.sup.7 are each independently a hydrogen atom or a group represented by —NR.sup.b.sub.2, —OR.sup.b, or —SR.sup.b, with the proviso that at least one of R.sup.5 to R.sup.7 is a group represented by —SR.sup.b.

##STR00001##

The disclosure provides an electrolyte solution capable of improving the output characteristics of an electrochemical device at initial stage and after high-temperature storage. The electrolyte solution contains a compound represented by the following formula (1). In the formula (1), R.sup.101s are each individually an optionally fluorinated organic group; X.sup.101s are each individually a halogen atom, —R.sup.c101, or —OR.sup.c101, wherein R.sup.c101 is an alkyl group or an aryl group; p1 is an integer of 1 to 4; and q1 is an integer satisfying p1+q1=4. Formula (1):

##STR00001##