Separators for electrochemical cells

a technology of electrochemical cells and separators, applied in the field of porous membranes, can solve the problems of long time for filling the battery with electrolyte, poor wet separator materials, and low separation efficiency, and achieve the effect of increasing the safety of the separator

Inactive Publication Date: 2013-07-04
OPTODOT CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]To achieve increased safety in separators for use in electric current producing cells such as batteries and capacitors, the present invention utilizes non-flammable inorganic oxides, such as aluminum oxides, and preferably non-flammable organic polymers having fluorinated groups in the separators. This invention utilizes various inorganic oxide particle pretreatment, mixing, coating, drying, and delaminating methods for preparing such separators.

Problems solved by technology

When the separator material is a polyolefin material that has non-polar surface properties, the electrolyte materials (which typically have highly polar properties) often poorly wet the separator material.
This results in longer times to fill the battery with electrolyte and potentially in low capacities in the battery due to a non-uniform distribution of electrolyte materials in the electrolyte element.
The separators used for lithium ion batteries are typically polyolefin separators, which melt at below 200° C. and are very flammable.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0034]A 20% by weight dispersion of DISPAL 10SR, the trade name for a surface-modified aluminum oxide available from SASOL North America, Houston, Tex., in methyl ethyl ketone was prepared. According to the Material Safety Data Sheet (MSDS) by SASOL for DISPAL 10SR, the aluminum oxide is an aluminum boehmite, and the surface modification comprises p-toluenesulfonic acid (PTSA). Separately, a 10% by weight solution of KYNAR HSV 900 in N-methyl pyrrolidone (NMP) was prepared. The aluminum oxide dispersion was added to the stirred fluoropolymer solution to prepare a dispersion containing the aluminum oxide and fluoropolymer in a dry weight ratio of 5:1. The % solids of this dispersion was about 17%.

[0035]This dispersion was coated onto a 3 mil thick silicone treated polyester (PET) film on the silicone release side to give a dry coating thickness of about 20 microns and then delaminated from the release substrate to provide a free standing aluminum oxide microporous separator with a po...

example 2

[0037]The aluminum oxide and fluoropolymer dispersion of Example 1 was coated onto a 20 micron thick polyolefin separator from Ube and dried at 90° C. to avoid shrinkage and melting of the polyolefin separator. The thickness of the coating was varied from 1 to 4 microns dry and coated on one or both sides of the polyolefin separator. Button cells as described in Example 1 were prepared with a 2 micron thick aluminum oxide microporous coating on one or both sides of the polyolefin separator and gave comparable stability at 55° C., cycling, and conductivity to control button cells with the polyolefin separator only.

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Abstract

Provided are separators for use in batteries and capacitors comprising (a) at least 50% by weight of an aluminum oxide and (b) an organic polymer, wherein the aluminum oxide is surface modified by treatment with an organic acid to form a modified aluminum oxide, and wherein the treatment provides dispersibility of the aluminum oxide in aprotic solvents such as N-methyl pyrrolidone. Preferably, the organic acid is a sulfonic acid, such as p-toluenesulfonic acid. Also preferably, the organic polymer is a fluorinated polymer, such as polyvinylidene fluoride. Also provided are electrochemical cells and capacitors comprising such separators.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of International Application Ser. No. PCT / US2011 / 001274, filed Jul. 18, 2011, which claims the benefit of U.S. provisional patent application Ser. No. 61 / 399,883, filed Jul. 19, 2010, the entirety of each which is hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to the field of porous membranes and to the fields of electric current producing cells and of separators for use in electric current producing cells. More particularly, this invention pertains to a porous separator membrane comprising an aluminum oxide and an organic polymer where the aluminum oxide has been surface modified by treatment with an organic acid to provide dispersibility in aprotic organic solvents. Also, the present invention pertains to electric current producing cells, such as lithium ion cells and capacitors, comprising such porous separators.BACKGROUND[0003]An electroactive mat...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01M2/16H01G9/02
CPCH01G9/02H01G11/52Y02E60/13H01M10/0525Y02E60/122H01M2/166Y10T428/249978Y02E60/10H01M50/446H01M50/431H01M50/426H01M50/491H01M50/403H01M50/417H01M50/449H01M4/382
Inventor XU, ZHONGCARLSON, STEVEN A.
Owner OPTODOT CORP
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