Nonaqueous electrolyte, and lithium-ion secondary cell and lithium-ion capacitor in which same is used

Patent metadata

Field	Value
Publication number	US-2018114651-A1
Application number	US-201515566023-A
Country	US
Kind code	A1
Filing date	Nov 16, 2015
Priority date	Apr 17, 2015
Publication date	Apr 26, 2018
Grant date	—

Abstract

Provided are (1) a nonaqueous electrolytic solution having lithium hexafluorophosphate dissolved in a nonaqueous solvent containing a cyclic carbonate and a linear carbonate, the nonaqueous electrolytic solution including, as a dissolution aid of lithium difluorophosphate, a linear ether compound containing a methoxy group and having a carbon number of 2 or more, a ratio (% by volume/% by mass) of a proportion (% by volume) of the dissolution aid to the total volume of the nonaqueous solvent to an amount (% by mass) of lithium difluorophosphate in the nonaqueous electrolytic solution being 0.1 or more and 5 or less, and lithium difluorophosphate being dissolved in an amount of 1.2% by mass or more at 25° C.; and (2) a lithium secondary battery and a lithium ion capacitor each using the nonaqueous electrolytic solution. The nonaqueous electrolytic solution is excellent in output characteristics and high temperature cyclic property and is capable of suppressing a metal elution amount.

First claim

1 . A nonaqueous electrolytic solution, comprising:
a nonaqueous solvent comprising a cyclic carbonate and a linear carbonate; lithium hexafluorophosphate dissolved in the nonaqueous solvent; and a dissolution aid of lithium difluorophosphate, wherein the dissolution aid is at least one selected from the group consisting of triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether, a ratio of a proportion of the dissolution aid to the total volume of the nonaqueous solvent to an amount of the lithium difluorophosphate in the nonaqueous electrolytic solution is 0.1 or more and 5 or less; and the lithium difluorophosphate is dissolved in an amount of 1.2% by mass or more at 25° C.

2 . The nonaqueous electrolytic solution according to claim 1 , comprising 1.1% by mass or more and 10% by mass or less of the dissolution aid.

3 . The nonaqueous electrolytic solution according to claim 1 , wherein a molar ratio of the dissolution aid to the lithium difluorophosphate is 0.1 or more and 2.5 or less.

4 . The nonaqueous electrolytic solution according to claim 1 , wherein a mass ratio of the dissolution aid to the lithium difluorophosphate is 0.1 or more and 5 or less.

5 . The nonaqueous electrolytic solution according to claim 1 , further comprising a linear carboxylic acid ester.

6 . The nonaqueous electrolytic solution according to claim 5 , wherein the linear carboxylic acid ester is ethyl acetate.

7 . The nonaqueous electrolytic solution according to claim 1 , wherein a volume ratio of [(amount of the cyclic carbonate)/(amount of the linear carbonate)] is from 10/90 to 45/55.

8 . A lithium ion secondary battery comprising:
the nonaqueous electrolytic solution according to claim 1 .

9 . A lithium ion capacitor comprising:
the nonaqueous electrolytic solution according to claim 1 .

10 . The nonaqueous electrolytic solution according to claim 1 ,
wherein the cyclic carbonate is at least two selected from the group consisting of ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolan-2-one, and vinylene carbonate.

11 . The nonaqueous electrolytic solution according to claim 1 ,
wherein a mass ratio of the lithium hexafluorophosphate to the lithium difluorophosphate (LiPF 6 /LiPO 2 F 2 ) is 3 or more.

Assignees

• Ube Industries

Inventors

• Shimamoto Kei
• Kishida Yousuke

Classifications

• H01G11/06

  with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC] · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M2300/0037

  Mixture of solvents · CPC title

• H01G11/60 Primary

  characterised by the solvent · CPC title

• H01G11/62

  characterised by the solute, e.g. salts, anions or cations therein · CPC title