Secondary battery

Abstract

A secondary battery in which graphite that is an active material can occlude and release lithium efficiently is provided. Further, a highly reliable secondary battery in which the amount of lithium inserted and extracted into/from graphite that is an active material is prevented from varying is provided. The secondary battery includes a negative electrode including a current collector and graphite provided over the current collector, and a positive electrode. The graphite includes a plurality of graphene layers. Surfaces of the plurality of graphene layers are provided substantially along the direction of an electric field generated between the positive electrode and the negative electrode.

What is claimed is: 
     
         1 . A secondary battery comprising:
 a negative electrode comprising a current collector provided with graphite, the graphite comprising a plurality of graphene layers; and   a positive electrode,   wherein surfaces of the plurality of graphene layers are provided substantially in parallel to a direction of an electric field generated between the positive electrode and the negative electrode.   
     
     
         2 . The secondary battery according to  claim 1 ,
 wherein edges of the plurality of graphene layers are each terminated by one or more of —O—Si, —O—P, —O-M, —Si, —P, and -M, and   wherein M is a metal element.   
     
     
         3 . The secondary battery according to  claim 1 ,
 wherein edges of the plurality of graphene layers each have a structure of one or more of C—O—Si, C—O—P, C—O-M, C—Si, C—P, and C-M, and   wherein M is a metal element.   
     
     
         4 . The secondary battery according to  claim 1 , wherein edges of the plurality of graphene layers are in contact with the current collector. 
     
     
         5 . The secondary battery according to  claim 1 , wherein the graphite is a highly oriented pyrolytic graphite. 
     
     
         6 . An electronic device comprising the secondary battery according to  claim 1 . 
     
     
         7 . A secondary battery comprising:
 a negative electrode comprising a current collector provided with graphite, the graphite comprising a first plurality of graphene layers and a second plurality of graphene layers; and   a positive electrode,   wherein surfaces of the first plurality of graphene layers are provided substantially in parallel to a direction of an electric field generated between the positive electrode and the negative electrode,   wherein surfaces of the second plurality of graphene layers are provided substantially in parallel to the direction of the electric field generated between the positive electrode and the negative electrode, and   wherein a normal direction of the first plurality of graphene layers and a normal direction of the second plurality of graphene layers are different from each other.   
     
     
         8 . The secondary battery according to  claim 7 ,
 wherein edges of the first plurality of graphene layers are each terminated by one or more of —O—Si, —O—P, —O-M, —Si, —P, and -M, and   wherein M is a metal element.   
     
     
         9 . The secondary battery according to  claim 7 ,
 wherein edges of the first plurality of graphene layers each have a structure of one or more of C—O—Si, C—O—P, C—O-M, C—Si, C—P, and C-M, and   wherein M is a metal element.   
     
     
         10 . The secondary battery according to  claim 7 , wherein edges of the first plurality of graphene layers and edges of the second plurality of graphene layers are in contact with the current collector. 
     
     
         11 . The secondary battery according to  claim 7 , wherein the graphite is a highly oriented pyrolytic graphite. 
     
     
         12 . An electronic device comprising the secondary battery according to  claim 7 . 
     
     
         13 . A secondary battery comprising:
 a negative electrode comprising a current collector provided with graphite, the graphite comprising a first plurality of graphene layers and a second plurality of graphene layers; and   a positive electrode,   wherein surfaces of the first plurality of graphene layers are provided substantially in parallel to a direction of an electric field generated between the positive electrode and the negative electrode,   wherein surfaces of the second plurality of graphene layers are provided substantially in parallel to the direction of the electric field generated between the positive electrode and the negative electrode, and   wherein the second plurality of graphene layers is stacked over the first plurality of graphene layers.   
     
     
         14 . The secondary battery according to  claim 13 , wherein a normal direction of the first plurality of graphene layers and a normal direction of the second plurality of graphene layers are parallel to each other. 
     
     
         15 . The secondary battery according to  claim 13 , wherein a normal direction of the first plurality of graphene layers and a normal direction of the second plurality of graphene layers are orthogonal to each other. 
     
     
         16 . The secondary battery according to  claim 13 ,
 wherein edges of the first plurality of graphene layers are each terminated by one or more of —O—Si, —O—P, —O-M, —Si, —P, and -M, and   wherein M is a metal element.   
     
     
         17 . The secondary battery according to  claim 13 ,
 wherein edges of the first plurality of graphene layers each have a structure of one or more of C—O—Si, C—O—P, C—O-M, C—Si, C—P, and C-M, and   wherein M is a metal element.   
     
     
         18 . The secondary battery according to  claim 13 , wherein edges of the first plurality of graphene layers are in contact with the current collector. 
     
     
         19 . The secondary battery according to  claim 13 , wherein the graphite is a highly oriented pyrolytic graphite. 
     
     
         20 . An electronic device comprising the secondary battery according to  claim 13 .