# US 12,218,379 B2 · Multilayer microporous separators for lithium ion secondary batteries and related methods

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,218,379 B2
- Document ID: US12218379B2
- Status: Granted
- Kind: B2
- Application number: 18/370,360
- Filed: 2023-09-19
- Published: 2024-01-04
- Granted: 2025-02-04
- Earliest claimed: 2014-11-26
- Assignees: Celgard, LLC
- Applicants: Celgard, LLC
- Inventors: Xiaomin Zhang; Lie Shi; William John Paulus
- Web page: https://patentgrep.com/patent/US12218379B2

## CPC

- H01M 50/403: Manufacturing processes of separators, membranes or diaphragms
- H01M 50/417: Polyolefins
- H01M 50/457: comprising three or more layers
- H01M 50/489: Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M 50/491: Porosity
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 2220/20: Batteries in motive systems, e.g. vehicle, ship, plane
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

An improved multilayer laminated microporous battery separator for a lithium ion secondary battery, and/or a method of making or using this separator is provided. The preferred inventive dry process separator is a tri-layer laminated Polypropylene/Polyethylene/Polypropylene microporous membrane with a thickness range of 12 μm to 30 μm having improved puncture strength and low electrical resistance for improved cycling and charge performance in a lithium ion battery. In addition, the preferred inventive separator's or membrane's low Electrical Resistance and high porosity provides superior charge rate performance in a lithium battery for high power applications.

## Claims

### Claim 1

A separator having three layers having the formation of two outer layers and one interior layer, each layer produced according to a dry stretch process in which a polyolefin resin, mix or blend is extruded to form said layers, said resin of each of the outer layers having a melt flow index (MFI) of less than or equal to about 0.8 grams/10 minute; and
wherein said separator having a thickness 12 μm, a porosity in the range of about 35% to about 65%, and an electrical resistance (ER) value of less than or equal to about 1.5 ohm-cm2, and
wherein the separator is a has a puncture strength (PS) of at least 280 gf has a porosity in the range of about 35% to 65%, has an ER of 1.5 ohm-cm2 or less.

### Claim 2 (depends on 1)

The separator of claim 1 wherein the separator layers are laminated following extrusion.

### Claim 3 (depends on 1)

The separator of claim 1 wherein the separator has a puncture strength (PS) of at least 330 gf and has a thickness of at least 14 μm.

### Claim 4 (depends on 1)

The separator of claim 1 wherein the separator has a puncture strength (PS) of at least 350 gf and has a thickness of at least 16 μm.

### Claim 5 (depends on 1)

The separator of claim 1 wherein the separator has a porosity of from 39% to 65%.

### Claim 6 (depends on 1)

The separator of claim 1 wherein the separator has a porosity in the range of 39% to 53%.

### Claim 7 (depends on 1)

The separator of claim 1 wherein the separator has an ER of 1.5 ohm-cm2 or less, and has a porosity of 35%.

### Claim 8 (depends on 1)

The separator of claim 1 wherein each outer layer is extruded from a polypropylene resin to form said layer.