Crosslinked Structure-Containing Separator for Lithium Secondary Battery, Method for Manufacturing the Same, and Lithium Secondary Battery Including the Separator

Patent metadata

Field	Value
Publication number	US-2024250381-A1
Application number	US-202218289632-A
Country	US
Kind code	A1
Filing date	May 9, 2022
Priority date	May 7, 2021
Publication date	Jul 25, 2024
Grant date	—

Abstract

The present disclosure relates to a crosslinked structure-containing separator for a lithium secondary battery, including: a crosslinked structure-containing polyolefin porous support having a crosslinked structure including polymer chains interconnected directly with one another; and a photoinitiator having an oxidation potential at least 0.02 V higher than the fully charged voltage of the lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the separator. The lithium secondary battery including the separator has excellent high-temperature safety and can improve the problem of degradation of capacity after high-temperature storage.

First claim

1 . A crosslinked structure-containing separator for a lithium secondary battery, comprising:
a crosslinked structure-containing polyolefin porous support having a crosslinked structure comprising polymer chains interconnected directly with one another; and a photoinitiator having an oxidation potential of at least 0.02 V higher than a fully charged voltage of the lithium secondary battery.

2 . The crosslinked structure-containing separator according to claim 1 , wherein the oxidation potential of the photoinitiator is from 4.4 to 8 V.

3 . The crosslinked structure-containing separator according to claim 1 , wherein the photoinitiator is included in an amount ranging from 0.015 tp 0.36 parts by weight based on 100 parts by weight of the crosslinked structure-containing polyolefin porous support.

4 . The crosslinked structure-containing separator according to claim 1 , 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 . The crosslinked structure-containing separator according to claim 1 , 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 first binder polymer; and
a porous adhesive layer disposed on the inorganic composite porous layer, wherein the porous adhesive layer comprising a second binder polymer.

6 . The crosslinked structure-containing separator according to claim 1 , wherein the photoinitiator comprises thioxanthone (TX), a thioxanthone derivative, benzophenone (BPO), a benzophenone derivative, or two or more of them.

7 . The crosslinked structure-containing separator according to claim 1 , which has a meltdown temperature of 160° C. or higher.

8 . The crosslinked structure-containing according to claim 1 , which has a shutdown temperature of 145° C. or less.

9 . A method for manufacturing a crosslinked structure-containing separator for a lithium secondary battery, comprising:
preparing a polyolefin porous support comprising a photoinitiator having an oxidation potential at least 0.02 V higher than the fully charged voltage of the lithium secondary battery; and irradiating ultraviolet rays to the polyolefin porous support.

10 . The method according to claim 9 , wherein the preparing the polyolefin porous support comprises coating and drying a photoinitiator composition containing the photoinitiator and a solvent on an outer side of the polyolefin porous support.

11 . The method according to claim 10 , wherein the photoinitiator composition is a slurry for an inorganic composite porous layer comprising an inorganic filler, a binder polymer, the photoinitiator, and the solvent.

12 . The method according to claim 10 , wherein the coating and drying comprises:
coating a slurry comprising an inorganic filler, a first binder polymer and a dispersion medium on at least one surface of a 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 a top surface of the inorganic composite porous layer, followed by drying to form a porous adhesive layer.

13 . The method according to claim 9 , wherein the oxidation potential of the photoinitiator from 4.4 to 8 V.

14 . The method according to claim 9 , wherein the photoinitiator is included in an amount ranging from 0.015 to 0.36 parts by weight based on 100 parts by weight of the crosslinked structure-containing polyolefin porous support.

15 . The method according to claim 9 , wherein the photoinitiator comprises thioxanthone (TX), a thioxanthone derivative, benzophenone (BPO), a benzophenone derivative, or two or more of them.

16 . The method according to claim 9 , wherein the ultraviolet rays are irradiated at an irradiation light dose of 10-2000 mJ/cm 2 .

17 . 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 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Han Sung-Jae
• Lee Joo-Sung
• Mun Sung Cik
• Lee A-Young
• Jung Kil-An

Classifications

• H01M50/417 Primary

  Polyolefins · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/431

  Inorganic material · CPC title

• H01M50/491

  Porosity · CPC title

• H01M10/0525

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