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.

1 - 19 . (canceled) 
     
     
         20 . A positive electrode comprising:
 a conductive additive; and   an active material covered by a carbon film,   wherein the conductive additive comprises a planar region and a particulate region,   wherein the planar region is larger than the active material, and   wherein the particulate region is smaller than the active material.   
     
     
         21 . The positive electrode according to  claim 20 , wherein a volume of the particulate region is 0.1 to 10 times a volume of the planar region. 
     
     
         22 . The positive electrode according to  claim 20 ,
 wherein a first proportion of carbon atoms in the planar region is 80% to 90% in X-ray photoelectron spectroscopy,   wherein a second proportion of oxygen atoms in the planar region is 10% to 20% in X-ray photoelectron spectroscopy, and   wherein a sum of the first proportion and the second proportion is less than 100%.   
     
     
         23 . The positive electrode according to  claim 22 , wherein a proportion of sp 2 -bonded carbon atoms among the carbon atoms is higher than or equal to 50% and lower than or equal to 80%. 
     
     
         24 . The positive electrode according to  claim 20 , wherein the active material comprises LiFePO 4 . 
     
     
         25 . The positive electrode according to  claim 20 , wherein the active material comprises one of LiFeO 2 , LiCoO 2 , LiNiO 2  and LiMn 2 O 4 . 
     
     
         26 . The positive electrode according to  claim 20 , further comprising a binder. 
     
     
         27 . The positive electrode according to  claim 26 , wherein the binder comprises polyvinylidene difluoride. 
     
     
         28 . A lithium secondary battery comprising:
 the positive electrode according to  claim 20 ;   a negative electrode; and   an electrolytic solution.   
     
     
         29 . The lithium secondary battery according to  claim 28 , wherein the electrolytic solution comprises one of ethylene carbonate and diethylene carbonate. 
     
     
         30 . An electric vehicle comprising the lithium secondary battery according to  claim 28 . 
     
     
         31 . A hybrid vehicle comprising the lithium secondary battery according to  claim 28 . 
     
     
         32 . A moving object comprising the lithium secondary battery according to  claim 28 . 
     
     
         33 . A system comprising the lithium secondary battery according to  claim 28  as an auxiliary power supply. 
     
     
         34 . An electric appliance comprising the lithium secondary battery according to  claim 28 . 
     
     
         35 . A positive electrode comprising:
 a conductive material; and   an active material covered by a carbon film,   wherein the conductive material comprises a planar region and a particulate region,   wherein the planar region is larger than the active material, and   wherein the particulate region is smaller than the active material.   
     
     
         36 . The positive electrode according to  claim 35 , wherein a volume of the particulate region is 0.1 to 10 times a volume of the planar region. 
     
     
         37 . The positive electrode according to  claim 35 ,
 wherein a first proportion of carbon atoms in the planar region is 80% to 90% in X-ray photoelectron spectroscopy,   wherein a second proportion of oxygen atoms in the planar region is 10% to 20% in X-ray photoelectron spectroscopy, and   wherein a sum of the first proportion and the second proportion is less than 100%.   
     
     
         38 . The positive electrode according to  claim 37 , wherein a proportion of sp 2 -bonded carbon atoms among the carbon atoms is higher than or equal to 50% and lower than or equal to 80%. 
     
     
         39 . The positive electrode according to  claim 35 , wherein the active material comprises LiFePO 4 . 
     
     
         40 . The positive electrode according to  claim 35 , wherein the active material comprises one of LiFeO 2 , LiCoO 2 , LiNiO 2  and LiMn 2 O 4 . 
     
     
         41 . A lithium secondary battery comprising:
 the positive electrode according to  claim 35 ;   a negative electrode; and   an electrolytic solution.   
     
     
         42 . The lithium secondary battery according to  claim 41 , wherein the electrolytic solution comprises one of ethylene carbonate and diethylene carbonate. 
     
     
         43 . An electric vehicle comprising the lithium secondary battery according to  claim 41 . 
     
     
         44 . A hybrid vehicle comprising the lithium secondary battery according to  claim 41 . 
     
     
         45 . A moving object comprising the lithium secondary battery according to  claim 41 . 
     
     
         46 . A system comprising the lithium secondary battery according to  claim 41  as an auxiliary power supply. 
     
     
         47 . An electric appliance comprising the lithium secondary battery according to  claim 41 . 
     
     
         48 . The positive electrode according to  claim 20 , wherein the particulate region comprises acetylene black. 
     
     
         49 . A positive electrode comprising:
 a conductive additive; and   an active material covered by a carbon film,   wherein the conductive additive comprises a planar region and a carbon nanofiber,   wherein the planar region is larger than the active material, and   wherein the carbon nanofiber is smaller than the active material.