Binder composition for secondary battery porous membrane, slurry for secondary battery porous membrane, porous membrane for secondary battery, and secondary battery

Patent metadata

Field	Value
Publication number	US-10256446-B2
Application number	US-201515116634-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Feb 27, 2014
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A binder composition for a porous membrane of a secondary battery, including a polycarboxylic acid and water, wherein the polycarboxylic acid includes a carboxylic acid group-containing monomer unit in an amount of 20% by weight or more and 50% by weight or less, the polycarboxylic acid is water-insoluble at a pH of 6.5 or less and water-soluble at a pH of 8 or more, and the binder composition for a porous membrane of a secondary battery has a pH of 6.5 or less; and a slurry for a porous membrane of a secondary battery using the binder composition, a porous membrane for a secondary battery, and a secondary battery.

First claim

The invention claimed is:

1. A binder composition for a porous membrane of a secondary battery, comprising a polycarboxylic acid and water, wherein
the polycarboxylic acid includes a carboxylic acid group-containing monomer unit in an amount of 20% by weight or more and 50% by weight or less,
the binder composition for a porous membrane of a secondary battery has a pH of 6.5 or less,
at least part of the polycarboxylic acid is dispersed in the water, and
the polycarboxylic acid has a haze of 60% or more at a pH of 6.5 and a haze of less than 60% at a pH of 8.0, wherein the haze is obtained by measuring scattered light and total transmitted light at an optical path length of 30 mm of an aqueous solution of the polycarboxylic acid having a concentration of 10%.

2. The binder composition for a porous membrane of a secondary battery according to claim 1 , wherein the polycarboxylic acid includes an alkyl (meth)acrylate unit in an amount of 50% by weight or more.

3. The binder composition for a porous membrane of a secondary battery according to claim 2 , wherein
the alkyl (meth)acrylate unit includes an alkyl (meth)acrylate unit (U1) having an alkyl group having 1 to 3 carbon atoms and an alkyl (meth)acrylate unit (U2) having an alkyl group having 4 to 6 carbon atoms, and
the unit (U1) and the unit (U2) in the polycarboxylic acid have a weight ratio U1/U2 of 1.0 to 10.0.

4. The binder composition for a porous membrane of a secondary battery according to claim 1 , wherein the polycarboxylic acid has a glass transition temperature of lower than 30° C.

5. A slurry for a porous membrane of a secondary battery, comprising a non-conductive particle, a polycarboxylic acid, and water, wherein
the polycarboxylic acid includes a carboxylic acid group-containing monomer unit in an amount of 20% by weight or more and 50% by weight or less,
the slurry for a porous membrane of a secondary battery has a pH of more than 7.0, and
the polycarboxylic acid has a haze of 60% or more at a pH of 6.5 and a haze of less than 60% at a pH of 8.0, wherein the haze is obtained by measuring scattered light and total transmitted light at an optical path length of 30 mm of an aqueous solution of the polycarboxylic acid having a concentration of 10%.

6. A porous membrane for a secondary battery, obtained by forming a layer of the slurry for a porous membrane of a secondary battery according to claim 5 and drying the formed layer.

7. A secondary battery comprising the porous membrane for a secondary battery according to claim 6 .

8. The binder composition for a porous membrane of a secondary battery according to claim 2 , wherein the polycarboxylic acid has a glass transition temperature of lower than 30° C.

9. The binder composition for a porous membrane of a secondary battery according to claim 3 , wherein the polycarboxylic acid has a glass transition temperature of lower than 30° C.

Assignees

• Zeon Corp

Inventors

• Ohkubo Yuuki

Classifications

• H01M10/0525

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

• H01M4/622

  being polymers · CPC title

• C08K2003/2227

  of aluminium · CPC title

• H01M10/052

  Li-accumulators · CPC title

• C08L33/062

  Copolymers with monomers not covered by C08L33/06 · CPC title