Crosslinked Structure-Containing Polyolefin Porous Support, Crosslinked Structure-Containing Separator For Lithium Secondary Battery Including The Same And Method For Manufacturing The Same, And Lithium Secondary Battery Including The Separator

Patent metadata

Field	Value
Publication number	US-2024234944-A1
Application number	US-202218289203-A
Country	US
Kind code	A1
Filing date	May 9, 2022
Priority date	May 7, 2021
Publication date	Jul 11, 2024
Grant date	—

Abstract

The present disclosure relates to a crosslinked structure-containing polyolefin porous support which has a number of double bonds present in the polyolefin chains of 0.01-0.6 per 1000 carbon atoms, as determined by 1 H-NMR, and includes a crosslinked structure having polymer chains interconnected directly with one another, a crosslinked structure-containing separator for a lithium secondary battery including the same and a method for manufacturing the same, and a lithium secondary battery including the separator. The crosslinked structure-containing separator for a lithium secondary battery has improved high-temperature safety, and thus can minimize degradation of the performance of a lithium secondary battery including the separator, even after storing the lithium secondary battery at high temperature.

First claim

1 . A crosslinked structure-containing polyolefin porous support comprises polymer chains interconnected directly with one another, wherein a number of double bonds are present in the polyolefin chains of 0.01-0.6 per 1000 carbon atoms, as determined by 1 H-NMR.

2 . The crosslinked structure-containing polyolefin porous support according to claim 1 , which has a crosslinking degree of 10-45%.

3 . A crosslinked structure-containing separator for a lithium secondary battery comprising the crosslinked structure-containing polyolefin support of claim 1 .

4 . The crosslinked structure-containing separator according to claim 3 , further comprising an inorganic composite porous layer disposed on at least one surface of the crosslinked structure-containing polyolefin porous support, wherein the inorganic composite porous layer comprises an inorganic filler and a binder polymer.

5 . (canceled)

6 . (canceled)

7 . The crosslinked structure-containing separator according to claim 3 , further comprising:
an inorganic composite porous layer disposed on at least one surface of the crosslinked structure-containing polyolefin porous support, and a porous adhesive layer disposed on the inorganic composite porous layer, wherein the inorganic composite porous layer includes an inorganic filler and a first binder polymer; and the porous adhesive layer includes a second binder polymer.

8 . (canceled)

9 . The crosslinked structure-containing separator according to claim 7 ,
wherein the first binder polymer comprises acrylic polymer, polyacrylic acid, styrene butadiene rubber, polyvinyl alcohol, or two or more of them, and/or wherein the second binder polymer comprises poly(vinylidene fluoride), poly(vinylidene fluoride-co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(methyl methacrylate), poly(ethylhexyl acrylate), poly(butyl acrylate), poly(acrylonitrile), poly(vinyl pyrrolidone), poly(vinyl acetate), poly(ethylhexyl acrylate-co-methyl methacrylate), poly(ethylene-co-vinyl acetate), polyethylene oxide, poly(arylate), or two or more of them.

10 . (canceled)

11 . The crosslinked structure-containing separator according to claim 3 , which has a meltdown temperature of 160° C. or higher.

12 . The crosslinked structure-containing separator according to claim 3 , which has a shutdown temperature of 145° C. or less.

13 . A method for manufacturing a crosslinked structure-containing separator for a lithium secondary battery, comprising:
preparing a polyolefin porous support comprising a photoinitiator, wherein the polyolefin porous support has a number of double bonds present in polyolefin chains of 0.01-0.5 per 1000 carbon atoms, as determined by 1 H-NMR; and irradiating ultraviolet rays to the polyolefin porous support, wherein a content of the photoinitiator ranges from 0.015-0.36 parts by weight based on 100 parts by weight of the polyolefin porous support.

14 . The method according to claim 13 , wherein in the preparing the polyolefin porous support, an antioxidant is further added, wherein a content of the antioxidant ranges from 500-20000 ppm based on a total weight of the polyolefin porous support.

15 . The method according to claim 14 , wherein the antioxidant comprises a first antioxidant which is a radical scavenger and a second antioxidant which is a peroxide decomposer.

16 . The method according to claim 15 , wherein the first antioxidant comprises a phenolic antioxidant, an amine-based antioxidant, or a mixture thereof.

17 . The method according to claim 15 , wherein the second antioxidant comprises a phosphorus-based antioxidant, a sulfur-based antioxidant, or a mixture thereof.

18 . The method according to claim 15 , wherein a content of the first antioxidant ranges from 500-10000 ppm based on a total weight of the polyolefin porous support, and a content of the second antioxidant ranges from 500-10000 ppm based on a total weight of the polyolefin porous support.

19 . The method according to claim 13 , wherein the photoinitiator comprises a Type 2 photoinitiator.

20 . The method according to claim 13 , wherein the photoinitiator comprises thioxanthone (TX), a thioxanthone derivative, benzophenone (BPO), a benzophenone derivative, or two or more of them.

21 . The method f according to claim 13 , wherein the preparing a polyolefin porous support comprises coating and drying a photo-crosslinking composition containing the photoinitiator and a solvent on the outer side of the polyolefin porous support.

22 . (canceled)

23 . (canceled)

24 . The method according to claim 21 , wherein the coating and drying the photo-crosslinking composition comprises:
coating a slurry comprising an inorganic filler, a first binder polymer and a dispersion medium on at least one surface of the polyolefin porous support, followed by drying, to form an inorganic composite porous layer; and applying a coating solution comprising a second binder polymer, the photoinitiator and the solvent to the top surface of the inorganic composite porous layer, followed by drying, to form a porous adhesive layer.

25 . The method according to claim 13 , wherein the ultraviolet rays are irradiated at an irradiation light dose of 10-2000 mJ/cm 2 .

26 . A lithium secondary battery comprising a positive electrode, a negative electrode and a separator for a lithium secondary battery interposed between the positive electrode and the negative electrode, wherein the separator for a lithium secondary battery is the crosslinked structure-containing separator of claim 3 .

Assignees

• Lg Chemical Ltd

Inventors

• Lee Joo-Sung
• Han Sung-Jae
• Mun Sung Cik
• Han Kyeong-Hwan

Classifications

• C08J7/0423

  with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder · CPC title

• C08J2323/26

  modified by chemical after-treatment · CPC title

• C08J7/18

  using wave energy or particle radiation · CPC title

• C08J3/24

  Crosslinking, e.g. vulcanising, of macromolecules (mechanical aspects B29C35/00; crosslinking agents C08K) · CPC title

• C08J9/365

  Coating · CPC title