Graphene and power storage device, and manufacturing method thereof

Abstract

The formation method of graphene includes the steps of forming a layer including graphene oxide over a first conductive layer; and supplying a potential at which the reduction reaction of the graphene oxide occurs to the first conductive layer in an electrolyte where the first conductive layer as a working electrode and a second conductive layer with a as a counter electrode are immersed. A manufacturing method of a power storage device including at least a positive electrode, a negative electrode, an electrolyte, and a separator includes a step of forming graphene for an active material layer of one of or both the positive electrode and the negative electrode by the formation method.

What is claimed is: 
     
         1 . A lithium secondary battery comprising:
 a positive electrode;   an electrolyte; and   a negative electrode,   wherein the negative electrode comprising:
 a negative electrode active material comprising a compound comprising silicon; and 
 a sheet-like conductive additive comprising a graphene comprising an oxygen atom, 
   wherein the sheet-like conductive additive clings to the negative electrode active material, and   wherein the negative electrode active material is in contact with the electrolyte.   
     
     
         2 . The lithium secondary battery according to  claim 1 , wherein the negative electrode active material is a particle. 
     
     
         3 . The lithium secondary battery according to  claim 1 , wherein the compound comprising silicon has an amorphous structure. 
     
     
         4 . A lithium secondary battery comprising:
 a positive electrode;   an electrolyte; and   a negative electrode,   wherein the negative electrode comprising:
 a negative electrode active material comprising a compound comprising silicon; and 
 a sheet-like conductive additive comprising a graphene comprising an oxygen atom, 
   wherein the negative electrode active material is at least partly surrounded with the sheet-like conductive additive, and   wherein the negative electrode active material is in contact with the electrolyte.   
     
     
         5 . The lithium secondary battery according to  claim 4 , wherein the negative electrode active material is a particle. 
     
     
         6 . The lithium secondary battery according to  claim 4 , wherein the compound comprising silicon has an amorphous structure. 
     
     
         7 . A lithium secondary battery comprising:
 a positive electrode;   an electrolyte; and   a negative electrode,   wherein the negative electrode comprising:
 a negative electrode active material comprising a compound comprising silicon; and 
 a sheet-like conductive additive comprising a graphene comprising an oxygen atom, 
   wherein the sheet-like conductive additive has a bag-like shape,   wherein the negative electrode active material is at least partly surrounded with the bag-like shape of the sheet-like conductive additive, and   wherein the negative electrode active material is in contact with the electrolyte.   
     
     
         8 . The lithium secondary battery according to  claim 7 , wherein the negative electrode active material is a particle. 
     
     
         9 . The lithium secondary battery according to  claim 7 , wherein the compound comprising silicon has an amorphous structure.