Electrode with porous protective film, nonaqueous electrolyte secondary battery, and method for manufacturing electrode with porous protective film
View Patent ↗An electrode with a porous protective film includes an electrode in which an active material layer is disposed on a collector and a porous protective film which is disposed on a surface of the active material layer and which contains fine particles, a binder, a surfactant, and a thickener. A nonaqueous electrolyte secondary battery includes a negative electrode in which a negative electrode active material layer is disposed on a negative electrode collector, a positive electrode in which a positive electrode active material layer is disposed on a positive electrode collector, a nonaqueous electrolyte, a separator, and a porous protective film which is disposed on at least one of a surface of the negative electrode active material layer or a surface of the positive electrode active material layer and which contains fine particles, a binder, a surfactant, and a thickener.
1. An electrode with a porous protective film, the electrode comprising:
an electrode in which an active material layer is disposed on a collector; and
a porous protective film which is disposed on a surface of the active material layer and which contains fine particles, a binder, a surfactant, and a thickener that is soluble in a solvent of a slurry used to form the porous protective film,
wherein a weight ratio of the thickener to the fine particles in the porous protective film ranges from 0.10 to 0.20.
2. The electrode with a porous protective film according to claim 1 , wherein the thickener comprises at least one type selected from the group consisting of hydroxyethyl cellulose, carboxymethyl cellulose, and polyethylene glycol.
3. The electrode with a porous protective film according to claim 1 , wherein the surfactant comprises at least one type selected from the group consisting of sodium dodecyl sulfate, lithium dodecyl sulfate, and sodium hexametaphosphate.
4. The electrode with a porous protective film according to claim 1 , wherein the fine particles comprises a metal oxide.
5. The electrode with a porous protective film according to claim 4 , wherein the metal oxide comprises at least one type selected from the group consisting of alumina, titania, zirconia, and silica.
6. The electrode with a porous protective film according to claim 1 , wherein the air permeability of the porous protective film is 3 to 600 sec/100 ml.
7. The electrode with a porous protective film according to claim 1 , wherein a thickness of the porous protective film ranges from 0.1 μm to 200 μm.
8. The electrode with a porous protective film according to claim 1 , wherein the binder contains a fluorine resin and a rubber resin, and the rubber resin comprises at least one type selected from the group consisting of styrene-butadiene rubber, acrylic rubber, and butadiene rubber.
9. A nonaqueous electrolyte secondary battery comprising:
a negative electrode in which a negative electrode active material layer is disposed on a negative electrode collector;
a positive electrode in which a positive electrode active material layer is disposed on a positive electrode collector;
a nonaqueous electrolyte;
a separator; and
a porous protective film which is disposed on at least one of a surface of the negative electrode active material layer and a surface of the positive electrode active material layer and which contains fine particles, a binder, a surfactant, and a thickener that is soluble in a solvent of a slurry used to form the porous protective film,
wherein a weight ratio of the thickener to the fine particles in the porous protective film ranges from 0.10 to 0.20.
10. The nonaqueous electrolyte secondary battery according to claim 9 , wherein a thickness of the porous protective film ranges from 0.1 μm to 200 μm.
11. A method for manufacturing an electrode with a porous protective film, the method comprising the steps of:
preparing a porous protective film-forming slurry by mixing fine particles, a binder, a surfactant, a solvent, and a thickener that is soluble in the solvent; and
applying the porous protective film-forming slurry to an electrode, in which an active material layer is disposed on a collector, and
conducting drying to form the porous protective film,
wherein a weight ratio of the thickener to the fine particles in the porous protective film ranges from 0.10 to 0.20.
12. The method for manufacturing an electrode with a porous protective film according to claim 11 , wherein a concentration of the thickener in the porous protective film-forming slurry is 0.50 to 1.0 percent by mass.
13. The method for manufacturing an electrode with a porous protective film according to claim 11 , wherein a concentration of the surfactant in the porous protective film-forming slurry is 0.01 to 3.0 percent by mass.
14. The method for manufacturing an electrode with a porous protective film according to claim 11 , wherein a thickness of the porous protective film ranges from 0.1 μm to 200 μm.
15. The method for manufacturing an electrode with a porous protective film according to claim 11 , wherein a viscosity of the slurry ranges from 0.1 Pa·s to 3.5 Pa·s.