Gel polymer electrolyte and lithium secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-2016028110-A1
Application number	US-201414413755-A
Country	US
Kind code	A1
Filing date	Oct 28, 2014
Priority date	Oct 29, 2013
Publication date	Jan 28, 2016
Grant date	—

Abstract

The present disclosure relates to a gel polymer electrolyte including an imide salt, and a lithium secondary battery including the same and having a protective film formed on a cathode tab. Disclosed are a gel polymer electrolyte that allows the production of a secondary battery having excellent quality with no corrosion of a cathode, while using, as an electrolyte, an imide-based salt effective for improvement of output quality and high-temperature storability, as well as a secondary battery including the same.

First claim

1 . A gel polymer electrolyte obtained by polymerizing a composition for a gel polymer electrolyte comprising a polymerizable monomer, a polymerization initiator, an electrolyte salt and an electrolyte solvent, wherein the electrolyte salt is an imide salt.

2 . The gel polymer electrolyte according to claim 1 , wherein the imide salt is a compound represented by the following Chemical Formula 1:
R 1 —SO 2 —N − (Li + )—SO 2 —R 2   [Chemical Formula 1]
wherein each of R 1 and R 2 independently represents fluorine (F) or a perfluoroalkyl.

3 . The gel polymer electrolyte according to claim 2 , wherein the compound represented by Chemical Formula 1 is at least one selected from the group consisting of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide and lithium bis(perfluoroethanesulfonyl)imide.

4 . The gel polymer electrolyte according to claim 1 , wherein the polymerizable monomer is an acrylate-based compound.

5 . The gel polymer electrolyte according to claim 1 , wherein the polymerizable monomer is at least one selected from the group consisting of 2-cyanoethyl acrylate, tetraethyleneglycol diacrylate, polyethyleneglycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylate tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, polyethyleneglycol diglycidyl ether, 1,5-hexadiene diepoxide, glycerol propoxylate triglycidyl ether, vinylcyclohexene dioxide, 1,2,7,8-diepoxyoctane, 4-vinylcyclohexene dioxide, butylglycidyl ether, diglycidyl 1,2-cyclohexanedicarboxylate, ethyleneglycol diglycidyl ether, glycerol triglycidyl ether and glycidyl methacrylate, or a mixture of two or more of them.

6 . The gel polymer electrolyte according to claim 1 , wherein the polymerizable monomer further comprises a monomer containing a functional group capable of inhibiting corrosion.

7 . The gel polymer electrolyte according to claim 6 , wherein the functional group capable of inhibiting corrosion is at least one selected from a phosphate group and sulfate group.

8 . The gel polymer electrolyte according to claim 6 , wherein the monomer containing a functional group capable of inhibiting corrosion is at least one compound selected from the group consisting of ethyleneglycol methacrylate phosphate, Mevinphos, 2-methacryloyloxyethyl phosphorylcholine, bis[2-(methacryloyloxy)ethyl]phosphate, Crotoxyphos, methyl (2E)-3[(dimethoxylphosphoryl)oxy]but-2-enoate, monoacryloxyethyl phosphate, 10-(phosphonoxy)decyl methacryate, 2-((diethoxyphosphinyl)oxy)ethyl methacrylate, (phosphonoxy)propane-1,3-diyl bismethacrylate, 2-sulfoethyl methacrylate, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-propenoic acid, 4-[(methylsulfonyl)oxy]butyl ester, 2-(methanesulfonyloxy)ethyl methacrylate and 2-(methanesulfonyloxy)ethyl acrylate.

9 . The gel polymer electrolyte according to claim 1 , which further comprises a corrosion inhibitor as an additive.

10 . The gel polymer electrolyte according to claim 9 , wherein the corrosion inhibitor is at least one selected from the group consisting of the compounds represented by the following Chemical Formula 2 to Chemical Formula 6:

(In Chemical Formula 2 and Chemical Formula 3, each of R 1 , R 2 and R 3 independently represents H, a C 1 -C 10 linear or branched alkyl group, a C 1 -C 10 linear or branched alkyl ester group, Na or Si(CH 3 ) 3 .)

(In Chemical Formula 4, R 1 is a C 1 -C 6 linear or branched alkylene group, a C 6 -C 12 arylene group or a C 2 -C 6 alkenylene group, and n is an integer of 1-10.)

(In Chemical Formula 5, each of R 2 -R 5 independently represents a C 1 -C 6 linear or branched alkylene group, O or —SO 2 — group.)

(In Chemical Formula 6, each of R 6 -R 11 independently represents a C 1 -C 6 linear or branched alkylene group, a C 6 -C 12 arylene group or a C 2 -C 6 alkenyl group, and m is an integer of 0-3.)

11 . The gel polymer electrolyte according to claim 9 , wherein the corrosion inhibitor is at least one selected from the group consisting of tris(trimethylsilyl)phosphate, tris(triethylsilyl)phosphate, NaH 2 PO 4 (sodium phosphate monobasic), Na 2 HPO 4 , Na 3 PO 4 , NaHSO 3 , Na 2 SO 3 , methylene methanedisulfonate, propane sultone, propene sultone, ethylene sulfate or ethylene sulfite.

12 . The gel polymer electrolyte according to claim 1 , which further comprises a lithium salt other than the imide salt as an electrolyte salt.

13 . The gel polymer electrolyte according to claim 12 , wherein the lithium salt is at least one selected from the group consisting of LiPF 6 , LiClO 4 , LiCl, LiBr, LiI, LiCoO 2 , LiBF 4 , LiB 10 Cl 10 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , LiAlO 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, chloroborane lithium, lithium lower aliphatic carbonate and lithium 4-phenylborate.

14 . The gel polymer electrolyte according to claim 12 , wherein the molar ratio of the lithium salt other than the imide salt:imide salt is 1:10 to 8:2.

15 . The gel polymer electrolyte according to claim 12 , wherein the molar ratio of the lithium salt other than the imide salt:imide salt is 2:8 to 7:3.

16 . The gel polymer electrolyte according to claim 1 , wherein the electrolyte salt is used in a concentration of 0.5M-2.0M based on the composition for a gel polymer electrolyte.

17 . A secondary battery comprising a cathode, an anode and the gel polymer electrolyte as defined in claim 1 .

18 . The secondary battery according to claim 17 , wherein the cathode comprises: a cathode collector; a cathode tab protruding from the cathode collector; and a protective film formed on the cathode tab.

19 . The secondary battery according to claim 18 , wherein the protective film comprises any one or a mixture of two or more selected from the group consisting of a polyethylene terephthalate (PET) film, polyimide (PI) film and a polypropylene (PP) film.

20 . The secondary battery according to claim 18 , wherein the protective film has a thickness of 1 μm to 100 μm.

21 . The secondary battery according to claim 18 , wherein the cathode tab is a non-coated portion having no cathode active material-coated portion.

22 . The secondary battery according to claim 18 , wherein the protective film is present in a ratio of 10%-90% based on the total length of the cathode tab along the protruding direction of cathode tab.

23 . The secondary battery according to claim 18 , wherein the protective film has the same width as the width of the cathode tab perpendicular to the protruding direction of cathode tab.

24 . The secondary battery according to claim 18 , wherein the cathode further comprises an insulating layer.

25 . The secondary battery according to claim 24 , wherein the insulating layer is present between the cathode tab an

Assignees

• Lg Chemical Ltd

Inventors

• Yu Sung Hoon
• Lee Kyung Mi
• Kang Yoo Sun
• Lee Jung Hoon
• Yang Doo Kyung

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M4/667

  in the form of layers, e.g. coatings · CPC title

• H01M10/0565 Primary

  Polymeric materials, e.g. gel-type or solid-type · CPC title

• H01M2300/0085

  Immobilising or gelification of electrolyte · CPC title

• H01M2220/30

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