Composite separator for electrochemical device and electrochemical device including the same

Patent metadata

Field	Value
Publication number	US-12266821-B2
Application number	US-202017631292-A
Country	US
Kind code	B2
Filing date	Jul 29, 2020
Priority date	Jul 30, 2019
Publication date	Apr 1, 2025
Grant date	Apr 1, 2025

Abstract

A composite separator for an electrochemical device, including: a porous polymer substrate having a plurality of pores; and a porous coating layer formed on at least one surface of the porous polymer substrate. The porous coating layer includes a plurality of particles and a binder positioned on at least a part of the surface of the particles to connect and fix the particles with one another. The particles include at least one of inorganic particles or organic particles, and the composite separator has a melt-down temperature of 170° C. or higher. An electrochemical device including the composite separator is also disclosed.

First claim

What is claimed is:

1. A composite separator for an electrochemical device, comprising:
a porous polymer substrate having a plurality of pores; and
a porous coating layer formed on at least one surface of the porous polymer substrate,
wherein the porous coating layer comprises a plurality of particles and a binder positioned on at least a part of the surface of the particles to connect and fix the particles with one another,
wherein the particles are inorganic particles having an average particle diameter of 10 nm to 380 nm,
a ratio (a/b) of an average diameter (a) of pores formed in the porous coating layer to an average diameter (b) of pores formed in the porous polymer substrate is 2.0 or less, and
wherein the composite separator has a melt-down temperature of 170° C. or higher.

2. The composite separator for the electrochemical device according to claim 1 , wherein a difference between a melt-down temperature of the porous polymer substrate of the composite separator and the melt-down temperature of the composite separator is 30° C. or higher.

3. The composite separator for the electrochemical device according to claim 1 , wherein the porous polymer substrate has a shut-down temperature of 140° C. or lower.

4. The composite separator for the electrochemical device according to claim 1 , wherein the composite separator has a melt-down temperature in a range of 170-220° C.

5. The composite separator for the electrochemical device according to claim 2 , wherein the difference between the melt-down temperature of the porous polymer substrate of the composite separator and the melt-down temperature of the composite separator is in a range of 30-90° C.

6. The composite separator for the electrochemical device according to claim 1 , wherein the particles are bound to one another by the binder, wherein the particles packed and in contact with each other, thereby forming interstitial volumes among the particles, and the interstitial volumes among the particles become vacant spaces to form the pores.

7. The composite separator for the electrochemical device according to claim 1 , wherein the ratio (a/b) of the average diameter (a) of the pores formed in the porous coating layer to the average diameter (b) of the pores formed in the porous polymer substrate is 0.75-1.25.

8. The composite separator for the electrochemical device according to claim 1 , wherein the average particle diameter of the inorganic particles is 10 nm-150 nm.

9. The composite separator for the electrochemical device according to claim 1 , wherein the binder is at least one of polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone, or an acrylic copolymer.

10. An electrochemical device comprising:
a cathode,
an anode, and
a separator interposed between the cathode and the anode,
wherein the separator is the composite separator according to claim 1 .

11. The electrochemical device according to claim 10 , wherein the electrochemical device is a lithium secondary battery.

Assignees

• Lg Chemical Ltd

Inventors

• Lee Joo-Sung
• Kim Bong-Tae
• Jung Kil-An

Classifications

• H01M10/0525

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

• Y02E60/10

  Energy storage using batteries · CPC title

• H01G9/02 Primary

  Diaphragms; Separators · CPC title

• H01M50/417

  Polyolefins · CPC title

• 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