Non-aqueous electrolyte solution and electricity storage device in which same is used

Patent metadata

Field	Value
Publication number	US-2017222268-A1
Application number	US-201515324800-A
Country	US
Kind code	A1
Filing date	Jul 13, 2015
Priority date	Jul 15, 2014
Publication date	Aug 3, 2017
Grant date	—

Abstract

Provided are a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the electrolyte salt including at least one first lithium salt selected from LiPF 6 , LiBF 4 , LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , and LiN(SO 2 C 2 F 5 ) 2 , and at least one second lithium salt selected from a lithium salt having an oxalate structure, a lithium salt having a phosphate structure, and a lithium salt having an S═O group, with a sum total of the first lithium salt and the second lithium salt being four or more, and an energy storage device using the same.
This nonaqueous electrolytic solution is not only able to improve electrochemical characteristics at a high temperature and much more improve a discharge capacity retention rate and low-temperature output characteristics after a high-temperature storage test but also able to improve low-temperature input characteristics even for high-density electrodes.

First claim

1 . A nonaqueous electrolytic solution, comprising an electrolyte salt dissolved in a nonaqueous solvent,
the electrolyte salt comprising at least one first lithium salt selected from the group consisting of LiPF 6 , LiBF 4 , LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , and LiN(SO 2 C 2 F 5 ) 2 , and at least one second lithium salt selected from the group consisting of a lithium salt having an oxalate structure, a lithium salt having a phosphate structure, and a lithium salt having an S═O group, with a sum total of the first lithium salt and the second lithium salt being four or more.

2 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises at least one lithium salt having an oxalate structure and two or more lithium salts selected from the group consisting of a lithium salt having a phosphate structure and a lithium salt having an S═O group as the second lithium salt.

3 . The nonaqueous electrolytic solution of claim 1 , wherein a ratio of a total molar concentration of the first lithium salt to a total molar concentration of the second lithium salt {(first lithium salt concentration)/(second lithium salt concentration)} is 1 or more.

4 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises one or more lithium salts having an oxalate structure, one or more lithium salts having a phosphate structure, and one or more lithium salts having an S═O group.

5 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises at least LiPF 6 as the first lithium salt.

6 . (canceled)

7 . The nonaqueous electrolytic solution of claim 1 , wherein the lithium salt having an oxalate structure is at least one selected from the group consisting of lithium bis(oxalate)borate, lithium dilluoro(oxalate)borate, lithium tetrafluoro(oxalate)phosphate, and lithium difluorobis(oxalate)phosphate.

8 . The nonaqueous electrolytic solution of claim 1 , wherein the lithium salt having a phosphate structure is at least one selected from the group consisting of lithium difluorophosphate and lithium fluorophosphate.

9 . The nonaqueous electrolytic solution of claim 1 , wherein the lithium salt having an S═O group is at least one selected from the group consisting of lithium fluorosulfonate, lithium methyl sulfate, lithium ethyl sulfate, lithium 2,2,2-trifluoroethyl sulfate, lithium trilluoro((methanesulfonyl)oxy)borate, and lithium pentafluoro((methanesulfonyl)oxy)phosphate.

10 . (canceled)

11 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous solvent comprises a cyclic carbonate and a linear ester.

12 . The nonaqueous electrolytic solution of claim 11 , wherein the cyclic carbonate comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolan-2-one, vinylene carbonate, and 4-ethynyl-1,3-dioxolan-2-one.

13 . The nonaqueous electrolytic solution of claim 11 , wherein the linear ester comprises both a symmetric linear carbonate and an asymmetric linear carbonate, and a content of the symmetric linear carbonate is more than a content of the asymmetric linear carbonate.

14 . The nonaqueous electrolytic solution of claim 11 , wherein the linear ester comprises a linear carboxylic acid ester.

15 . An energy storage device comprising a positive electrode, a negative electrode, and a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the electrolyte salt comprising at least one first lithium salt selected from the group consisting of LiPF 6 , LiBF 4 , LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , and LiN(SO 2 C 2 F 5 ) 2 , and at least one second lithium salt selected from the group consisting of a lithium salt having an oxalate structure, a lithium salt having a phosphate structure, and a lithium salt having an S═O group with a sum total of the first lithium salt and the second lithium salt being four or more.

16 . The energy storage device of claim 15 , wherein an active material of the positive electrode is a complex metal oxide comprising lithium and at least one selected from the group consisting of cobalt, manganese and nickel, or a lithium-containing olivine-type phosphate comprising at least one selected from the group consisting of iron, cobalt, nickel and manganese.

17 . The energy storage device of claim 15 , wherein an active material of the negative electrode comprises at least one selected from the group consisting of metal lithium, a lithium alloy, a carbon material capable of absorbing and releasing lithium, tin, a tin compound, silicon, a silicon compound, and a lithium titanate compound.

18 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises two kinds of a lithium salt having two oxalate structures and a lithium salt having one oxalate structure as the second lithium salt.

19 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises three kinds of a lithium salt having two oxalate structures, a lithium salt having one oxalate structure, and a lithium salt having a phosphate structure as the second lithium salt.

20 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises two or more lithium salt having an SO 4 group as the second lithium salt having an S═O group.

21 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises a lithium salt having a oxalate structure in an amount of 0.001 M or more and 0.2 M or less in the nonaqueous electrolytic solution as the second lithium salt.

22 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises a lithium salt having a phosphate structure in an amount of 0.001 M or more and 0.3 M or less in the nonaqueous electrolytic solution as the second lithium salt.

23 . The nonaqueous electrolytic solution of claim 1 , wherein the nonaqueous electrolytic solution comprises a lithium salt having an S═O group in an amount of 0.001 M or more and 0.3 M or less in the nonaqueous electrolytic solution as the second lithium salt.

Assignees

• Ube Industries

Inventors

• Abe Koji
• Shimamoto Kei

Classifications

• H01M2300/0091

  in the form of mixtures · CPC title

• H01G11/62

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

• H01M10/0568 Primary

  characterised by the solutes · CPC title

• Y02E60/13

  Energy storage using capacitors · CPC title

• H01M10/052

  Li-accumulators · CPC title