Negative electrode for power storage device, method for forming the same, and power storage device
An object is to suppress electrochemical decomposition of an electrolyte solution and the like at a negative electrode in a lithium ion battery or a lithium ion capacitor; thus, irreversible capacity is reduced, cycle performance is improved, or operating temperature range is extended. A negative electrode for a power storage device including a negative electrode current collector, a negative electrode active material layer which is over the negative electrode current collector and includes a plurality of particles of a negative electrode active material, and a film covering part of the negative electrode active material. The film has an insulating property and lithium ion conductivity.
1. An active material comprising:
a graphite particle having concavo-convex shape,
wherein a concave portion of the graphite particle is covered with an oxide film.
2. The active material according to claim 1 , wherein the oxide film has a conductivity of a carrier ion.
3. The active material according to claim 2 , wherein the carrier ion is a lithium ion.
4. The active material according to claim 1 , wherein the oxide film comprises Nb 2 O 5 .
5. The active material according to claim 1 , wherein the oxide film comprises silicon oxide.
6. The active material according to claim 1 , wherein the oxide film has a thickness in a range of 5 nm or more and 50 nm or less.
7. A power storage device comprising a battery having the active material according to claim 1 .
8. A battery comprising:
a positive electrode and a negative electrode; and
a separator between the positive electrode and the negative electrode,
wherein:
the negative electrode comprises a current collector and an active material including a graphite particle having concavo-convex shape, and
a concave portion of the graphite particle is covered with an oxide film.
9. The battery according to claim 8 , wherein the oxide film has a conductivity of a carrier ion.
10. The battery according to claim 9 , wherein the carrier ion is a lithium ion.
11. The battery according to claim 8 , wherein the oxide film comprises Nb 2 O 5 .
12. The battery according to claim 8 , wherein the oxide film comprises silicon oxide.
13. The battery according to claim 8 , wherein the oxide film has a thickness in a range of 5 nm or more and 50 nm or less.
14. The battery according to claim 8 , wherein the current collector has a tab region extending outside from an exterior body enveloping the positive electrode, the negative electrode, and the separator.