Porous membrane for secondary batteries, method for producing same, electrode for secondary batteries, separator for secondary batteries, and secondary battery
A porous membrane for a secondary battery, including non-conductive particles and a binder for a porous membrane, wherein the non-conductive particle is a polymer particle having a core-shell structure, the non-conductive particle has a core portion having a glass transition point of 30° C. to 90° C., the non-conductive particle has a shell portion having a glass transition point higher than that of the core portion by 10° C. or higher, a thickness of the shell portion is 0.01% to 3.0% of a number average particle diameter of the non-conductive particles, and a number average particle diameter (A) of the non-conductive particle and a number average particle diameter (B) of the binder for a porous membrane satisfy (A)>(B).
1. A porous membrane for a secondary battery, comprising non-conductive particles and a binder for a porous membrane, wherein
the non-conductive particle is a polymer particle having a core-shell structure,
the non-conductive particle has a core portion having a glass transition point of 30° C. to 90° C.,
the non-conductive particle has a shell portion having a glass transition point higher than that of the core portion by 10° C. or higher,
a thickness of the shell portion is 0.01% to 3.0% of a number average particle diameter of the non-conductive particles, and
a number average particle diameter (A) of the non-conductive particle and a number average particle diameter (B) of the binder for a porous membrane satisfy (A)>(B).
2. The porous membrane for a secondary battery according to claim 1 , wherein the shell portion of the non-conductive particles and the binder for a porous membrane contain 50% by weight or more of (meth)acrylate unit.
3. The porous membrane for a secondary battery according to claim 1 , wherein the non-conductive particles have a number average particle diameter of 100 nm to 1,500 nm.
4. A method for producing the porous membrane for a secondary battery according to claim 1 , comprising:
mixing the non-conductive particles, the binder for a porous membrane, and a medium to prepare a slurry for a porous membrane;
applying the slurry for a porous membrane onto a substrate to form a slurry layer; and
drying the slurry layer.
5. The method according to claim 4 , wherein
the medium is an aqueous medium, and
the slurry for a porous membrane is an aqueous dispersion.
6. An electrode for a secondary battery, comprising:
a current collector;
an electrode material layer that contains an electrode active material and a binding agent for an electrode material layer, and adheres to the current collector, and
the porous membrane according to claim 1 that is formed on the electrode material layer.
7. A separator for a secondary battery, comprising:
an organic separator; and
the porous membrane according to claim 1 that is formed on the organic separator.
8. A secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolytic solution, wherein
at least any one of the positive electrode, the negative electrode, and the separator has the porous membrane according to claim 1 .