Non-aqueous electrolyte solution for secondary batteries, and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2016141720-A1
Application number	US-201615008638-A
Country	US
Kind code	A1
Filing date	Jan 28, 2016
Priority date	Sep 24, 2013
Publication date	May 19, 2016
Grant date	—

Abstract

To provide a flame retardant non-aqueous electrolyte solution for secondary batteries, with which a lithium ion secondary battery which is less likely to undergo thermal runaway and which is excellent in the high temperature storage properties can be obtained; and a lithium ion secondary battery using the non-aqueous electrolyte solution for secondary batteries.
A non-aqueous electrolyte solution for secondary batteries, comprising an electrolyte salt and a liquid composition,
which contains either one or both of monofluorophosphate anions and difluorophosphate anions derived from at least part of the electrolyte salt,
wherein at least a lithium salt is contained as one type of the electrolyte salt, and
the liquid composition comprises at least one fluorine-containing solvent (α) selected from the group consisting of a fluorine-containing ether compound, a fluorine-containing chain carboxylic acid ester compound and a fluorine-containing chain carbonate compound, and a cyclic carboxylic acid ester compound. A lithium ion secondary battery using the non-aqueous electrolyte solution for secondary batteries.

First claim

What is claimed is:

1 . A non-aqueous electrolyte solution for secondary batteries, comprising an electrolyte salt and a liquid composition,
which contains either one or both of monofluorophosphate anions and difluorophosphate anions derived from at least part of the electrolyte salt, wherein at least a lithium salt is contained as one type of the electrolyte salt, and the liquid composition comprises at least one fluorine-containing solvent (α) selected from the group consisting of a fluorine-containing ether compound, a fluorine-containing chain carboxylic acid ester compound and a fluorine-containing chain carbonate compound, and a cyclic carboxylic acid ester compound.

2 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the ratio of the sum of the mass of the monofluorophosphate anions and the mass of the difluorophosphate anions to the total mass of the non-aqueous electrolyte solution is from 0.001 to 2 mass %.

3 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the liquid composition further contains at least one compound (β) selected from the group consisting of a saturated cyclic carbonate compound, a saturated chain carbonate compound having no fluorine atom, a saturated cyclic sulfone compound (excluding a lithium salt) and a phosphoric acid ester compound.

4 . The non-aqueous electrolyte solution for secondary batteries according to claim 3 , wherein the ratio of the mass of the saturated chain carbonate compound having no fluorine atom to the total mass of the non-aqueous electrolyte solution is at most 30 mass %.

5 . The non-aqueous electrolyte solution for secondary batteries according to claim 3 , wherein the ratio of the sum of the mass of the saturated cyclic carbonate compound and the mass of the saturated chain carbonate compound having no fluorine atom to the total mass of the non-aqueous electrolyte solution is at most 30 mass %.

6 . The non-aqueous electrolyte solution for secondary batteries according to claim 3 , wherein (N A +N B )/N Li , i.e. the ratio of the sum of the total number of moles (N A ) of the cyclic carboxylic acid ester compound and the total number of moles (N B ) of the compound (β) to the total number of moles (N Li ) of lithium atoms derived from the lithium salt, is from 3.0 to 7.0.

7 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the fluorine-containing solvent (α) contains the fluorine-containing ether compound.

8 . The non-aqueous electrolyte solution for secondary batteries according to claim 7 , wherein the fluorine-containing ether compound is at least one member selected from the group consisting of compounds represented by the following formula (1):
R 1 —O—R 2   (1)

(wherein each of R 1 and R 2 which are independent of each other, is a C 1-10 alkyl group, a C 3-10 cycloalkyl group, a C 1-10 fluorinated alkyl group, a C 3-10 fluorinated cycloalkyl group, a C 2-10 alkyl group having at least one etheric oxygen atom, or a C 2-10 fluorinated alkyl group having at least one etheric oxygen atom, provided that one or each of R 1 and R 2 is a C 1-10 fluorinated alkyl group, a C 3-10 fluorinated cycloalkyl group or a C 2-10 fluorinated alkyl group having at least one etheric oxygen atom).

9 . The non-aqueous electrolyte solution for secondary batteries according to claim 8 , wherein the compound represented by the formula (1) contains at least one member selected from the group consisting of CF 3 CH 2 OCF 2 CHF 2 , CF 3 CH 2 OCF 2 CHFCF 3 , CHF 2 CF 2 CH 2 OCF 2 CHF 2 , CH 3 CH 2 CH 2 OCF 2 CHF 2 , CH 3 CH 2 OCF 2 CHF 2 and CHF 2 CF 2 CH 2 OCF 2 CHFCF 3 .

10 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the lithium salt contains LiPF 6 .

11 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the fluorine-containing chain carboxylic acid ester compound is at least one member selected from the group consisting of compounds represented by the following formula (2):

(wherein each of R 3 and R 4 which are independent of each other, is a C 1-3 alkyl group or a C 1-3 fluorinated alkyl group, provided that one or each of R 3 and R 4 is a fluorinated alkyl group).

12 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the cyclic carboxylic acid ester compound is at least one member selected from the group consisting of compounds represented by the following formula (4):

(wherein each of R 7 to R 12 which are independent of one another, is a hydrogen atom, a fluorine atom, a chlorine atom, a C 1-2 alkyl group, a C 1-2 fluorinated alkyl group or a C 2-3 alkyl group having an etheric oxygen atom, and n is an integer of from 1 to 3).

13 . The non-aqueous electrolyte solution for secondary batteries according to claim 12 , wherein the compound represented by the formula (4) is at least one member selected from the group consisting of γ-butyrolactone, γ-valerolactone and ε-caprolactone.

14 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the ratio of the mass of the fluorine-containing solvent (α) to the total mass of the non-aqueous electrolyte solution is from 30 to 80 mass %.

15 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein N A /N Li , i.e. the ratio of the total number of moles (N A ) of the cyclic carboxylic acid ester compound to the total number of moles (N Li ) of lithium atoms derived from the lithium salt, is from 1.5 to 7.0.

16 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , which has a lithium salt content of from 0.7 to 1.5 mol/L.

17 . The non-aqueous electrolyte solution for secondary batteries according to claim 1 , wherein the ratio of the mass of the cyclic carboxylic acid ester compound to the total mass of the non-aqueous electrolyte solution is from 4 to 50 mass %.

18 . A lithium ion secondary battery comprising a positive electrode containing, as an active material, a material capable of absorbing and desorbing lithium ions, a negative electrode containing, as an active material, at least one member selected from the group consisting of metal lithium, a lithium alloy and a carbon material capable of absorbing and desorbing lithium ions, and the non-aqueous electrolyte solution for secondary batteries as defined in claim 1 .

Assignees

• Asahi Glass Co Ltd

Inventors

• Onozaki Yu
• Murotani Eisuke
• Enta Toyokazu

Classifications

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M10/0569 Primary

  characterised by the solvents · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M2300/0037

  Mixture of solvents · CPC title