Polyolefin separator and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-12451560-B2
Application number	US-202017441367-A
Country	US
Kind code	B2
Filing date	Mar 20, 2020
Priority date	Mar 22, 2019
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

A polyolefin separator is provided in the present disclosure. The polyolefin separator includes a polyolefin porous substrate including a plurality of fibrils and pores formed by the fibrils draped across one another. A coating layer surrounding the outer side of the fibrils is contained in the polyolefin porous substrate and the coating layer includes a crosslinked polymer, wherein the polyolefin separator having the coating layer has a change in air permeability of 20% or less and a change in basis weight of 4% or less, as compared to the polyolefin porous substrate. A method for manufacturing the polyolefin separator and a secondary battery including the polyolefin separator are also disclosed.

First claim

What is claimed is:

1. A polyolefin separator, comprising:
a polyolefin porous substrate comprising a plurality of fibrils and pores formed by the fibrils draped across one another; and
coating layers surrounding an outer side of the fibrils contained in the polyolefin porous substrate and the coating layers comprising a crosslinked polymer,
wherein the coating layers surround the outside of the fibrils not only on the polyolefin separator surface but also inside the polyolefin separator, and are not separate coating layers differentiated from the porous substrate but are layers formed on the surface of each of the fibrils, and
wherein the polyolefin separator having the coating layers has a change in air permeability of 20% or less and a change in basis weight of 4% or less, as compared to the polyolefin porous substrate.

2. The polyolefin separator according to claim 1 , wherein the crosslinked polymer is formed by UV curing of a crosslinking agent and a photoinitiator.

3. The polyolefin separator according to claim 1 , wherein the polyolefin separator having the coating layer has a change in air permeability of 3%-20% and a change in basis weight of 0.5%-4%, as compared to the polyolefin porous substrate.

4. A method for manufacturing a polyolefin separator, comprising:
preparing a photocurable composition containing a crosslinking agent, a photoinitiator and a solvent;
dipping a polyolefin porous substrate comprising a plurality of fibrils in the photocurable composition and drying the polyolefin porous substrate at room temperature so that the photocurable composition is coated on surfaces of the fibrils of the polyolefin porous substrate; and
carrying out UV curing on one or both surfaces of the polyolefin porous substrate coated with the photocurable composition to form coating layers,
wherein the polyolefin separator having the coating layers has a change in air permeability of 20% or less and a change in basis weight of 4% or less, as compared to the polyolefin porous substrate.

5. A method for manufacturing the polyolefin separator according to claim 1 , comprising:
introducing a polyolefin and a diluting agent to an extruder and mixing the polyolefin and the diluting agent therein, and carrying out extrusion to prepare an extruded polyolefin composition;
allowing the extruded polyolefin composition to pass through a die and cold casting roll to mold the extruded polyolefin composition in the form of a molded sheet;
orienting the molded sheet;
elongating the molded sheet to form an elongated sheet;
extracting the diluting agent from the elongated sheet to form an extracted elongated sheet;
dipping the extracted elongated sheet from which the diluting agent is extracted in a photocurable composition containing a crosslinking agent, a photocuring initiator and a solvent, and carrying out drying at room temperature so that the photocurable composition is coated on the surfaces of fibrils of the elongated sheet to form a coated elongated sheet; and
thermally fixing the coated elongated sheet coated,
the method further comprising carrying out UV curing of one or both surfaces of the coated elongated sheet, before or after the thermal fixing step, thereby forming coating layers,
wherein the polyolefin separator having the coating layers has a change in air permeability of 20% or less and a change in basis weight of 4% or less, as compared to the polyolefin porous substrate.

6. The method according to claim 4 , wherein the crosslinking agent is a multi-functional (meth)acrylate monomer.

7. The method according to claim 6 , wherein the crosslinking agent is a (meth)acrylate monomer having 2 to 5 carbon-carbon double bonded groups.

8. The method according to claim 4 , wherein the crosslinking agent comprises triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, bis(meth)acryloyloxyethyl phosphate, trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, trimethylolpropane PO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, 2,2,2-tris(meth)acryloyloxy methylethylsuccinic acid, ethoxylated isocyanuric acid tri(meth)acrylate, tris-(2-(meth)acryloxyethyl) isocyanurate, glycerin EO-added tri(meth)acrylate, glycerin PO-added tri(meth)acrylate, tris (meth)acryloyloxyethyl phosphate, trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol EO-added tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, or two or more thereof.

9. The method according to claim 4 , wherein the photoinitiator comprises benzoin methyl ether, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide (TPO), bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide, α,α-methoxy-α-hydroxyacetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-on, 1-hydroxy-cyclohexyl-phenylketone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, or two or more thereof.

10. The method according to claim 4 , wherein the weight ratio of the crosslinking agent to the photoinitiator is from 1:1 to 10:1.

11. The method according to claim 4 , wherein each of the content of the crosslinking agent and that of the photoinitiator is independently 0.1 wt %-20 wt %, based on 100 wt % of the photocurable composition.

12. A secondary battery comprising a positive electrode, a negative electrode and a polyolefin separator interposed between the positive electrode and the negative electrode, wherein the polyolefin separator is defined in claim 1 .

13. A secondary battery comprising a positive electrode, a negative electrode and a polyolefin separator interposed between the positive electrode and the negative electrode, wherein the polyolefin separator is defined in claim 2 .

14. A secondary battery comprising a positive electrode, a negative electrode and a polyolefin separator interposed between the positive electrode and the negative electrode, wherein the polyolefin separator is defined in claim 3 .

15. The method according to claim 5 , wherein the crosslinking agent is a multi-functional (meth)acrylate monomer.

16. The method according to claim 5 , wherein the crosslinking agent comprises triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, bis(meth)acryloyloxyethyl phosphate, trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, trimethylolpropane PO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, 2,2,2-tris(meth)acryloyloxy methylethylsuccinic acid, ethoxylated isocyanuric acid tri(meth)acrylate, tris-(2-(meth)acryloxyethyl) isocyanurate, glycerin EO-added tri(meth)acrylate, glycerin PO-added tri(meth)acrylate, tris (meth)acryloyloxyethyl phosphate, trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol EO-added tetra(meth)acrylate, dipentaerythritol penta(me

Assignees

• Lg Chemical Ltd

Inventors

• Han Sung-Jae
• Lee Joo-Sung
• Bae Won-Sik
• Ryu Bi-Oh

Classifications

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/409

  Separators, membranes or diaphragms characterised by the material · CPC title

• H01M50/449

  having a layered structure · CPC title

• H01M50/417 Primary

  Polyolefins · CPC title