Negative electrode slurry composition, lithium ion secondary battery negative electrode, and lithium ion secondary battery
Provided is a negative electrode slurry composition including a binder resin, a water-soluble polymer, and a negative electrode active material, wherein the binder resin including (A) a styrene-butadiene copolymer latex having a gel amount of 70 to 98% and having a glass transition temperature in dynamic viscoelasticity measurement with a single peak at −30° C. to 60° C. and (B) a polymer latex formed of a hetero-phase structure having a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at −100° C. to 10° C. and having a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at 10° C. to 100° C., and the negative electrode active material including a carbon-based active material and a silicon-based active material.
1. A negative electrode slurry composition comprising a binder resin, a water-soluble polymer, and a negative electrode active material,
wherein the binder resin comprising (A) a styrene-butadiene copolymer latex having a gel amount of 70 to 98% and having a glass transition temperature in dynamic viscoelasticity measurement with a single peak at −30° C. to 60° C. and (B) a polymer latex formed of a hetero-phase structure having a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at −100° C. to 10° C. and having a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at 10° C. to 100° C.,
a mass ratio (St/BD) of a styrene unit (St) and a 1,3-butadiene unit (BD) in the (A) styrene-butadiene copolymer latex is 55/45 to 87/13, and
the negative electrode active material comprising a carbon-based active material and a silicon-based active material.
2. The negative electrode slurry composition according to claim 1 , wherein the (B) polymer latex has a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at −60° C. to 10° C., and has a glass transition temperature in dynamic viscoelasticity measurement with at least one peak at 10° C. to 65° C.
3. The negative electrode slurry composition according to claim 1 , wherein the negative electrode slurry composition comprises 0.1 to 50 parts by mass of the (B) polymer latex in terms of a solid content based on 100 parts by mass of the (A) styrene-butadiene copolymer latex in terms of a solid content.
4. The negative electrode slurry composition according to claim 1 , wherein the negative electrode active material contains 0.1 to 50 parts by mass of the silicon-based active material based on 100 parts by mass of the carbon-based active material contained in the negative electrode active material.
5. The negative electrode slurry composition according to claim 1 , wherein the silicon-based active material is SiO x (0.01≦x<2) formed of at least one of SiO and SiO 2 , and Si.
6. The negative electrode slurry composition according to claim 1 , wherein at least one of the silicon-based active materials is combined with conductive carbon.
7. A lithium ion secondary battery negative electrode which is formed by applying the negative electrode slurry composition according to claim 1 onto a current collector and drying the negative electrode slurry composition.
8. A lithium ion secondary battery comprising the lithium ion secondary battery negative electrode according to claim 7 .