Binder for lithium ion secondary battery electrode, slurry obtained using the binder for electrode, electrode obtained using the slurry, and lithium ion secondary battery using the electrode
View Patent ↗An object of the present invention is to provide: a binder for a lithium ion secondary battery electrode, which is water-dispersible type and has favorable adhesion between active materials and between the active material and current collectors, along with charge-discharge high-temperature cycle characteristics; a slurry using the binder; an electrode using the slurry; and a lithium ion secondary battery using the electrode. The present invention relates to a binder composition for a lithium ion secondary battery electrode, which is obtained by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a surfactant, the ethylenically unsaturated monomer containing, as essential constituents, 15 to 70 mass % of styrene with respect to the total mass of ethylenically unsaturated monomers, an ethylenically unsaturated carboxylic acid ester, an ethylenically unsaturated carboxylic acid and an internal cross-linking agent.
1. A binder for a lithium ion secondary battery electrode,
being obtained by emulsion polymerization of ethylenically unsaturated monomers containing, as essential constituents, 15 to 70 mass % of styrene with respect to the total mass of ethylenically unsaturated monomers, 0.1 to 5 mass % of an ethylenically unsaturated carboxylic acid ester having a polar group with respect to the total mass of ethylenically unsaturated monomers, an ethylenically unsaturated carboxylic acid, another ethylenically unsaturated carboxylic acid ester, and an internal cross-linking agent in the presence of a surfactant, and
having a glass transition temperature of 30° C. or lower.
2. The binder for a lithium ion secondary battery electrode according to claim 1 ,
wherein a dried film has a swelling resistance rate of 300% or less to an electrolytic solution at 60° C.
3. The binder for a lithium ion secondary battery electrode according to claim 1 ,
wherein the ethylenically unsaturated carboxylic acid is contained at 1 to 10 mass % with respect to the total mass of ethylenically unsaturated monomers.
4. The binder for a lithium ion secondary battery electrode according to claim 1 ,
wherein the internal cross-linking agent is contained at 0.1 to 5 mass % with respect to the total mass of ethylenically unsaturated monomers.
5. A slurry for a lithium ion secondary battery electrode,
being obtained by using the binder for a lithium ion secondary battery electrode according to claim 1 and an active material.
6. An electrode for a lithium ion secondary battery,
being obtained by using the slurry for a lithium ion secondary battery electrode according to claim 5 .
7. A lithium ion secondary battery,
being obtained by using the electrode for a lithium ion secondary battery according to claim 6 .
8. A slurry for a lithium ion secondary battery electrode,
being obtained by using the binder for a lithium ion secondary battery electrode according to claim 1 , an active material, and carboxymethyl cellulose.