Aqueous binder composition for secondary battery electrode, slurry for secondary battery electrode, binder, secondary battery electrode, and secondary battery
An aqueous binder composition for a secondary battery electrode containing a silane coupling agent without ethylenically unsaturated bonds, a resin which is a polymer of at least one kind of ethylenically unsaturated monomers, a resin which is a polymer of at least one kind of ethylenically unsaturated monomer, and at least one kind of solvent selected from water and a hydrophilic solvent. The amount of silane coupling agent is from 0.5 to 9 parts by mass based on 100 parts by mass of ethylenically unsaturated monomer. The pH of the composition is 2.5 to 8.0. Also disclosed is a binder obtained by curing the aqueous binder composition, a slurry containing the aqueous binder composition and an active material, a secondary battery electrode obtained by curing the slurry, and a secondary battery including the secondary battery electrode.
1. A secondary battery electrode comprising a binder obtained by curing an aqueous binder composition, consisting essentially of:
a silane coupling agent without ethylenically unsaturated bonds,
a resin which is a copolymer of ethylenically unsaturated monomers, and
at least one kind of solvent selected from the group consisting of water and a hydrophilic solvent,
wherein the ethylenically unsaturated monomers comprise an internal crosslinking agent,
an amount of the internal crosslinking agent is 0.01 to 5% by mass based on the total amount of monomer components forming the copolymer,
an amount of the silane coupling agent is from 0.5 to 9.0 parts by mass based on 100 parts by mass of the ethylenically unsaturated monomers, and
pH of the aqueous binder composition is 2.5 to 8.0, and
a glass transition temperature of the resin is 30° C. or less.
2. The secondary battery electrode according to claim 1 ,
wherein the silane coupling agent is a silane coupling agent containing an epoxy group or a silane coupling agent containing amino group.
3. The secondary battery electrode according to claim 1 ,
wherein the ethylenically unsaturated monomers comprise a styrene and an ethylenically unsaturated carboxylic acid ester.
4. The secondary battery electrode according to claim 1 ,
wherein the ethylenically unsaturated monomers comprise styrene, an ethylenically unsaturated carboxylic acid ester having neither a hydroxyl group nor an glycidyl group, an ethylenically unsaturated carboxylic acid ester having at least one of a hydroxyl group and a glycidyl group, and an ethylenically unsaturated carboxylic acid,
an amount of the styrene is 10 to 70% by mass based on the total amount of monomer components forming the copolymer,
an amount of the ethylenically unsaturated carboxylic acid ester having neither a hydroxyl group nor a glycidyl group is 25 to 85% by mass based on the total amount of monomer components forming the copolymer,
an amount of the ethylenically unsaturated carboxylic acid ester having at least one of a hydroxyl group and a glycidyl group is 0.1 to 10% by mass based on the total amount of monomer components forming the copolymer, and
an amount of the ethylenically unsaturated carboxylic acid is 0.01% to 10% by mass based on the total amount of monomer components forming the copolymer.
5. The secondary battery electrode according to claim 4 ,
wherein the amount of the styrene is 30 to 60% by mass based on the total amount of monomer components forming the copolymer,
the amount of the ethylenically unsaturated carboxylic acid ester having neither a hydroxyl group nor a glycidyl group is 30 to 65% by mass based on the total amount of monomer components forming the copolymer,
the amount of the ethylenically unsaturated carboxylic acid ester having at least one of a hydroxyl group and a glycidyl group is 1 to 3% by mass based on the total amount of monomer components forming the copolymer, and
the amount of the ethylenically unsaturated carboxylic acid is 0.1% to 7% by mass based on the total amount of monomer components forming the copolymer.
6. The secondary battery electrode according to claim 4 ,
wherein
the internal crosslinking agent is a silane coupling agent which has at least one ethylenically unsaturated bond, and a reactive group reactive with the ethylenically unsaturated carboxylic acid ester having at least one of a hydroxyl group and a glycidyl group.
7. A secondary battery comprising the secondary battery electrode according to claim 1 .
8. The secondary battery electrode according to claim 1 ,
wherein the internal crosslinking agent consists of an internal crosslinking agent having at least two ethylenically unsaturated bonds.