Cellulose-based multilayer separator

Patent metadata

Field	Value
Publication number	US-10586967-B2
Application number	US-201615545129-A
Country	US
Kind code	B2
Filing date	Mar 30, 2016
Priority date	Mar 30, 2015
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

The present invention relates to a separator for a secondary battery which is capable of improving a shut-down function of a cellulose-based multilayer separator physically having high strength. The separator for a secondary battery comprises a substrate formed of cellulose-based nanofibers and polyethylene nanoparticles; and a resin layer stacked on one surface or both surfaces of the substrate, the resin being formed from a polyolefin.

First claim

What is claimed is:

1. A separator for a secondary battery, comprising:
a substrate comprising cellulose-based nanofiber and polyethylene nano particles,
wherein the cellulose-based nanofiber and polyethylene nano particles are a homogenous mixture; and
a resin layer stacked on both surfaces of the substrate, the resin being formed from a polyolefin,
wherein the cellulose-based nanofiber and the polyethylene nano particles are present in a weight ratio of 7:3 to 9:1.

2. The separator of claim 1 , wherein the polyolefin is at least one selected from a group consisting of polyethylene, polypropylene, polybutylene and polypentene.

3. The separator of claim 1 , wherein the polyethylene nano particles have a melting point of 80 to 100° C., and the polyolefin resin has a melting point of 100 to 140° C.

4. The separator of claim 1 , wherein the resin layer further comprises inorganic particles and a polymeric binder.

5. The separator of claim 1 , wherein the resin layer is stacked in a lamination method.

6. The separator of claim 1 , wherein the resin layer has a thickness of 3 to 20 μm, and the substrate has a thickness of 5 to 20 μm.

7. The separator of claim 1 , wherein the cellulose-based nanofiber is made of any one selected from a group consisting of cellulose acetate, cellulose triacetate and cellulose butylate.

8. The separator of claim 1 , wherein the cellulose-based nanofiber has a diameter of 10 nm to 500 nm and a length of 1 μm to 10 mm, and the polyethylene nano particle has a particle size of 50 nm to 500 nm.

9. A method of preparing a separator for a secondary battery, the method comprising:
forming a sheet using a homogenous mixture of a cellulose nanofiber and polyethylene nano particles dispersed in a solvent;
removing the solvent to provide a porous substrate; and
stacking a resin layer formed from a polyolefin on both surfaces of the substrate in a lamination method,
wherein the cellulose-based nanofiber and the polyethylene nano particles are present in a weight ratio of 7:3 to 9:1.

10. The method of claim 9 , wherein the solvent comprises a resin for forming pores and at least one selected from a group consisting of water, methyl alcohol, ethyl alcohol, propyl alcohol, acetone, ethyl acetate, methyl ethyl ketone and toluene, to which is added.

11. The method of claim 10 , wherein the resin for forming pores is at least one selected from a group consisting of polyethylene glycol, polyvinyl alcohol and polyvinyl propylene.

Assignees

• Lg Chemical Ltd

Inventors

• Park Jong-Pil
• Kim Jong-Hun

Classifications

• B32B23/08 Primary

  of synthetic resin · CPC title

• B32B2260/025

  Particulate layer · CPC title

• B32B2307/54

  Yield strength; Tensile strength · CPC title

• B32B2307/732

  Dimensional properties · CPC title

• B32B5/16

  characterised by features of a layer formed of particles, e.g. chips, powder {or granules (layer formed of natural mineral particles B32B19/00; layer being formed of wood fibres, chips or particles B32B21/02)} · CPC title