Nonaqueous electrolytic solution and energy storage device using same

Patent metadata

Field	Value
Publication number	US-2017256819-A1
Application number	US-201715446655-A
Country	US
Kind code	A1
Filing date	Mar 1, 2017
Priority date	Mar 1, 2016
Publication date	Sep 7, 2017
Grant date	—

Abstract

Provided are a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the nonaqueous electrolytic solution containing 0.01 to 4% by mass of a compound represented by the following general formula (I), and an energy storage device including the nonaqueous electrolytic solution:

wherein R 1 and R 2 each independently represent a methyl group, an ethyl group, or a fluoroethyl group. The nonaqueous electrolytic solution and the energy storage device have improved high-temperature storage property and low-temperature cycle property.

First claim

What is claimed is:

1 . A nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the nonaqueous electrolytic solution comprising 0.01 to 4% by mass of a compound represented by the following general formula (I):

wherein R 1 and R 2 each independently represent a methyl group, an ethyl group, or a fluoroethyl group.

2 . The nonaqueous electrolytic solution according to claim 1 , wherein the compound represented by the general formula (I) is one or two selected from (1,1′-biphenyl)-2,2′-diyl dimethyl bis(carbonate), and (1,1′-biphenyl)-2,2′-diyl diethyl bis(carbonate).

3 . The nonaqueous electrolytic solution according to claim 1 , wherein the nonaqueous solvent comprises a cyclic carbonate and a linear ester.

4 . The nonaqueous electrolytic solution according to claim 3 , wherein the cyclic carbonate comprises one or more selected from ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolan-2-one, vinylene carbonate, and 4-ethynyl-1,3-dioxolan-2-one.

5 . The nonaqueous electrolytic solution according to claim 3 , wherein the linear ester comprises both a symmetric linear carbonate and an asymmetric linear carbonate, and the content of the symmetric linear carbonate is larger than the content of the asymmetric linear.

6 . The nonaqueous electrolytic solution according to claim 3 , wherein the linear ester comprises one or more selected from one or more asymmetric linear carbonates selected from the group consisting of methyl ethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, and ethyl propyl carbonate; one or more symmetric linear carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate; and one or more linear carboxylate selected from the group consisting of methyl pivalate, ethyl pivalate, propyl pivalate, methyl propionate, ethyl propionate, propyl propionate, methyl acetate, and ethyl acetate.

7 . The nonaqueous electrolytic solution according to claim 1 , wherein the nonaqueous electrolytic solution further comprises one or more lithium salts selected from the group consisting of a lithium salt having a oxalate structure, a lithium salt having a phosphate structure, a lithium salt having a S═O group, and a lithium salt composed of a lithium cation with an ether compound selected from 2,5,8,11-tetraoxadodecane and 2,5,8,11,14-pentaoxapentadecane as a ligand and a difluorophosphate anion, and a total content of the lithium salts in the nonaqueous electrolytic solution is preferably 0.001 mol/L to 0.5 mol/L.

8 . The nonaqueous electrolytic solution according to claim 7 , wherein the lithium salt having a oxalate structure is one or more selected from the group consisting of lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium tetrafluoro(oxalate)phosphate, and lithium difluorobis(oxalate)phosphate.

9 . The nonaqueous electrolytic solution according to claim 7 , wherein the lithium salt having a phosphate structure is one or more selected from the group consisting of LiPO 2 F 2 and Li 2 PO 3 F.

10 . The nonaqueous electrolytic solution according to claim 7 , wherein the lithium salt having a S═O group is one or more selected from the group consisting of lithium trifluoro((methanesulfonyl)oxy)borate, lithium pentafluoro((methanesulfonyl)oxy)phosphate, lithium methylsulfate, lithium ethylsulfate, lithium 2,2,2-trifluoroethylsulfate, and FSO 3 Li.

11 . The nonaqueous electrolytic solution according to claim 1 , wherein the electrolyte salt comprises one or more selected from the group consisting of LiPF 6 , LiBF 4 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , and LiN(SO 2 F) 2 .

12 . The nonaqueous electrolytic solution according to claim 1 , which is a nonaqueous electrolytic solution for an energy storage device.

13 . 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, wherein the nonaqueous electrolytic solution comprises 0.01 to 4% by mass of a compound represented by the following general formula (I):

wherein R 1 and R 2 each independently represent a methyl group, an ethyl group, or a fluoroethyl group.

14 . The energy storage device according to claim 13 , wherein the compound represented by the general formula (I) is one or two selected from (1,1′-biphenyl)-2,2′-diyl dimethyl bis(carbonate), and (1,1′-biphenyl)-2,2′-diyl diethyl bis(carbonate).

15 . The energy storage device according to claim 13 , wherein the nonaqueous solvent comprises a cyclic carbonate and a linear ester.

16 . The energy storage device according to claim 13 , wherein the positive electrode comprises a complex metal oxide containing lithium and one or more selected from the group consisting of cobalt, manganese, and nickel, or a lithium-containing olivine-type phosphate containing one or more selected from the group consisting of iron, cobalt, nickel, and manganese, as a positive electrode active material.

17 . The energy storage device according to claim 13 , wherein the negative electrode comprises one or more selected from metal lithium, a lithium alloy, a carbon material capable of absorbing and releasing lithium ions, elemental tin, a tin compound, elemental silicon, a silicon compound, and a lithium titanate compound, as a negative electrode active material.

Assignees

• Ube Industries

Inventors

• Kondo Masahide
• Kotou Yuichi
• Fukata Hiroto

Classifications

• H01M10/0567 Primary

  characterised by the additives · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M2300/0037

  Mixture of solvents · CPC title

• H01M2300/0025

  Organic electrolyte · CPC title