Binder composition for electrical storage device, slurry composition for electrical storage device electrode, electrode for electrical storage device, and electrical storage device
Provided is a binder composition for an electrical storage device that can both ensure stability of a slurry composition and enhance peel strength of an electrode and rate characteristics of an electrical storage device. The binder composition contains a particulate polymer. The particulate polymer includes a cyano group-containing monomer unit in a proportion of not less than 5 mass % and not more than 45 mass % and includes an amide group-containing monomer unit in a proportion of not less than 0.3 mass % and not more than 10 mass %. Moreover, the particulate polymer has a core-shell structure including a core portion and a shell portion at least partially covering an outer surface of the core portion, and has at least one glass-transition temperature at 10° C. or lower.
1. A binder composition for an electrical storage device comprising a particulate polymer, wherein
the particulate polymer includes a cyano group-containing monomer unit in a proportion of not less than 5 mass % and not more than 45 mass % and includes an amide group-containing monomer unit in a proportion of not less than 0.3 mass % and not more than 10 mass % when all monomer units included in the particulate polymer are taken to be 100 mass %,
the particulate polymer has a core-shell structure including a core portion and a shell portion at least partially covering an outer surface of the core portion, and the particulate polymer has at least one glass-transition temperature at 10° C. or lower,
a polymer of the core portion includes the cyano group-containing monomer unit,
a polymer of the shell portion includes the cyano group-containing monomer unit,
the particulate polymer includes the cyano group-containing monomer unit in the core portion in a larger amount than in the shell portion, and
a glass-transition temperature of the polymer of the shell portion is higher than a glass-transition temperature of the polymer of the core portion.
2. The binder composition for an electrical storage device according to claim 1 , wherein the particulate polymer has at least two glass-transition temperatures within a range of −80° C. to 80° C.
3. The binder composition for an electrical storage device according to claim 1 , wherein the core portion constitutes a proportion of not less than 30 mass % and not more than 70 mass % among a total of the core portion and the shell portion.
4. A slurry composition for an electrical storage device electrode comprising: an electrode active material; and the binder composition for an electrical storage device according to claim 1 .
5. An electrode for an electrical storage device comprising: an electrode mixed material layer formed using the slurry composition for an electrical storage device electrode according to claim 4 ; and a current collector.
6. An electrical storage device comprising the electrode for an electrical storage device according to claim 5 .
7. The binder composition for an electrical storage device according to claim 1 , wherein the proportion in which the polymer of the shell includes the cyano group-containing monomer unit when all monomer units included in the particulate polymer are taken to be 100 mass % is 1 mass % or more and 10 mass % or less.
8. The binder composition for an electrical storage device according to claim 1 , wherein the proportion in which the polymer of the shell includes the cyano group-containing monomer unit when all monomer units included in the particulate polymer are taken to be 100 mass % is 5 mass % or more and 10 mass % or less.