Battery separator with Z-direction stability

Patent metadata

Field	Value
Publication number	US-9570727-B2
Application number	US-57550605-A
Country	US
Kind code	B2
Filing date	Oct 18, 2005
Priority date	Oct 22, 2004
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A battery separator is a microporous membrane. The membrane has a major volume of a thermoplastic polymer and a minor volume of an inert particulate filler. The filler is dispersed throughout the polymer. The membrane exhibits a maximum Z-direction compression of 95% of the original membrane thickness. Alternatively, the battery separator is a microporous membrane having a TMA compression curve with a first substantially horizontal slope between ambient temperature and 125° C., a second substantially horizontal slope at greater than 225° C. The curve of the first slope has a lower % compression than the curve of the second slope. The curve of the second slope is not less than 5% compression. The TMA compression curve is graphed so that the Y-axis represents % compression from original thickness and the X-axis represents temperature.

First claim

We claim:

1. A battery separator comprising:
a single layer microporous membrane having a porosity in the range of 20-80% and an original thickness in a range of 4-25 microns, said microporous membrane comprising a thermoplastic polymer and an inert particulate filler having an average particle size of less than 1 micron, said thermoplastic polymer being selected from the group consisting of: polyethylene, polypropylene, polybutene, polymethylpentene, ultrahigh molecular weight polyethylene, copolymers thereof, and blends of the foregoing, said filler being dispersed throughout said polymer,
said single layer microporous membrane having a maximum Z-direction compression of 95% of the original single layer microporous membrane thickness at 250° C.

2. The battery separator of claim 1 wherein said inert particulate filler being selected from the group consisting of: carbon based materials, metal oxides and hydroxides, metal carbonates, minerals, synthetic and natural zeolites, cements, silicates, glass particles, sulfur-containing salts, synthetic polymers, and mixtures thereof.

3. The battery separator of claim 1 wherein the particulate comprises 1 to 99% by weight of said single layer microporous membrane.

4. The battery separator of claim 1 wherein said single layer microporous membrane has a maximum Z-direction compression of 85% of the original single layer microporous membrane thickness at 250° C.

5. The battery separator of claim 1 wherein said single layer microporous membrane has a TMA compression curve with a first substantially horizontal slope between ambient temperature and 125° C., a second substantially horizontal slope at greater than 225° C., wherein a Y-axis represents % compression from original thickness and a X-axis represents temperature, said curve of said first slope having a lower % compression than said curve of said second slope, and said curve of said second slope not being less than 5% compression.

6. The battery separator of claim 1 wherein the particulate comprises 1 to 70% by weight of said single layer microporous membrane.

7. A lithium-ion battery comprising the separator of claim 1 .

Assignees

• Zhang Zhengming
• Nguyen Khuy V
• Arora Pankaj
• Call Ronald W
• Simmons Donald K
• Dao Tien
• Celgard Llc

Inventors

• Zhang Zhengming
• Nguyen Khuy V
• Arora Pankaj
• Call Ronald W
• Simmons Donald K
• Dao Tien

Classifications

• Y02E60/122

  Cross-Sectional Technologies · mapped topic

• H01M10/052

  Li-accumulators · CPC title

• H01M2/166 Primary

  Electricity · mapped topic

• C08J5/2206 Primary

  based on organic and/or inorganic macromolecular compounds · CPC title

• H01M2/18

  Electricity · mapped topic