Negative electrode for power storage device, method for forming the same, and power storage device

Abstract

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 . (canceled) 
     
     
         2 . A lithium ion battery comprising:
 a positive electrode;   a negative electrode; and   an electrolyte between the positive electrode and the negative electrode,   wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer, and   wherein the negative electrode active material layer comprises a negative electrode active material comprising graphite and a graphene layer covering part of the negative electrode active material.   
     
     
         3 . The lithium ion battery according to  claim 2 , wherein an average diameter of the negative electrode active material is more than or equal to 6 μm and less than or equal to 30 μm. 
     
     
         4 . The lithium ion battery according to  claim 2 , wherein the graphene layer is in contact with the negative electrode active material. 
     
     
         5 . The lithium ion battery according to  claim 2 , wherein the lithium ion battery is flexible. 
     
     
         6 . A power storage device comprising the lithium ion battery according to  claim 2 . 
     
     
         7 . A lithium ion battery comprising:
 a positive electrode;   a negative electrode; and   an electrolyte between the positive electrode and the negative electrode,   wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer, and   wherein the negative electrode active material layer comprises a plurality of negative electrode active materials each comprising graphite and at least one graphene layer covering part of the plurality of negative electrode active materials.   
     
     
         8 . The lithium ion battery according to  claim 7 , wherein an average diameter of the plurality of negative electrode active materials is more than or equal to 6 μm and less than or equal to 30 μm. 
     
     
         9 . The lithium ion battery according to  claim 7 , wherein the graphene layer is in contact with the plurality of negative electrode active materials. 
     
     
         10 . The lithium ion battery according to  claim 7 , wherein the lithium ion battery is flexible. 
     
     
         11 . A power storage device comprising the lithium ion battery according to  claim 7 . 
     
     
         12 . A lithium ion battery comprising:
 a positive electrode;   a negative electrode; and   an electrolyte between the positive electrode and the negative electrode,   wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer, and   wherein the negative electrode active material layer comprises a plurality of negative electrode active material particles and at least one graphene layer covering part of the plurality of negative electrode active material particles.   
     
     
         13 . The lithium ion battery according to  claim 12 , wherein an average diameter of the plurality of negative electrode active material particles is more than or equal to 6 μm and less than or equal to 30 μm. 
     
     
         14 . The lithium ion battery according to  claim 12 , wherein the graphene layer is in contact with the plurality of negative electrode active material particles. 
     
     
         15 . The lithium ion battery according to  claim 12 , wherein the lithium ion battery is flexible. 
     
     
         16 . A power storage device comprising the lithium ion battery according to  claim 12 .