Ultrathin graphene piece, apparatus for preparing ultrathin graphene piece, method for preparing ultrathin graphene piece, capacitor, and method of manufacturing capacitor

Abstract

The problem addressed by the present invention is to provide an apparatus for preparing ultrathin graphene pieces capable of preparing ultrathin graphene pieces in which less than 10 pieces of graphene are overlapped in large quantities, a method for preparing ultrathin graphene pieces capable of preparing the ultrathin graphene pieces with high yield, an ultrathin graphene piece in which less than 10 pieces of graphene are overlapped, a capacitor having high performance by using the ultrathin graphene piece as an electrode, and an efficient method of manufacturing the capacitor. The above-described problem can be solved by using an apparatus 20 for preparing ultrathin graphene pieces, the apparatus comprising: a graphite electrode 21 ; a counter electrode 22 which is made of graphite, a corrosion resistant alloy, or a precious metal; an electrolytic solution 25 in which one end sides of the two electrodes 21 and 22 are immersed; a container 24 which stores the electrolytic solution 25 ; and a power source 28 which is connected to the two electrodes 21 and 22 via wirings 26 and 27 . The apparatus is also provided with a porous filter 23 so as to cover at least the immersed part of the graphite electrode 21 that is immersed in the electrolytic solution 25.

1 . An apparatus for preparing ultrathin graphene pieces, comprising:
 a graphite electrode;   a counter electrode which is made of graphite, a corrosion resistant alloy, or a precious metal;   an electrolytic solution in which one end sides of the two electrodes are immersed;   a container which stores the electrolytic solution; and   a power source which is connected to the two electrodes via wirings,   wherein a porous filter is provided so as to cover at least the immersed part of the graphite electrode that is immersed in the electrolytic solution.   
     
     
         2 . The apparatus for preparing ultrathin graphene pieces according to  claim 1 , wherein the graphite electrode is made of natural graphite or highly oriented pyrolytic graphite (HOPG). 
     
     
         3 . The apparatus for preparing ultrathin graphene pieces according to  claim 1 , wherein the counter electrode which is made of a precious metal is a platinum sheet. 
     
     
         4 . The apparatus for preparing ultrathin graphene pieces according to  claim 1 , wherein the electrolytic solution is an acid aqueous solution or an organic solvent. 
     
     
         5 . The apparatus for preparing ultrathin graphene pieces according to  claim 4 , wherein the acid aqueous solution is any of aqueous solutions of a sulfuric acid, a hydrochloric acid, and a nitric acid. 
     
     
         6 . The apparatus for preparing ultrathin graphene pieces according to  claim 4 , wherein the organic solvent is polypropylene carbonate to which 1 M of LiPF 6  is added. 
     
     
         7 . The apparatus for preparing ultrathin graphene pieces according to  claim 1 , wherein the porous filter is a filter paper. 
     
     
         8 . A method for preparing ultrathin graphene pieces, wherein the apparatus for preparing ultrathin graphene pieces according to  claim 1  is used, wherein a graphite electrode is used as an anode and a counter electrode is used as a cathode, and wherein a voltage is applied between the electrodes. 
     
     
         9 . The method for preparing ultrathin graphene pieces according to  claim 8 , wherein a first voltage applying step of applying a voltage which is +0.1 V to +10 V between the electrodes for 1 minute to 10 minutes, a second voltage applying step of applying a voltage which is +1 V to +10 V between the electrodes for 1 minute to 10 minutes, and a third voltage applying step of applying a voltage which is +5 V to +15 V between the electrodes for 1 hour to 2 hours, are sequentially performed. 
     
     
         10 . The method for preparing ultrathin graphene pieces according to  claim 9 , wherein the method comprising, after the third voltage applying step, an organic solvent dispersion step of dispersing powder which is obtained by filtering, washing, and drying the electrolytic solution in an organic solvent, and irradiating ultrasonic waves. 
     
     
         11 . The method for preparing ultrathin graphene pieces according to  claim 10 , wherein the organic solvent is any of N-methylpyrrolidone (NMP), dimethylformamide (DMF), N,N-Dimethylacetamide (DMA), γ-buthyrolactone (GBL), or 1,3-dimethyl-2-imidazolidinone (DMEU). 
     
     
         12 . The method for preparing ultrathin graphene pieces according to  claim 9 , wherein the method comprising, after the third voltage applying step, an activation processing step of applying a voltage which is +5 V to +15 V between the electrodes for 60 minutes to 120 minutes. 
     
     
         13 . The method for preparing ultrathin graphene pieces according to  claim 12 , wherein the method comprising, after the activation processing step, a modifying molecule removing step of applying a voltage in a reverse direction with the same value of the voltage applied in the activation processing step. 
     
     
         14 . The method for preparing ultrathin graphene pieces according to  claim 13 , wherein an operation which includes the activation processing step and the modifying molecule removing step is repeated two or more times. 
     
     
         15 . An ultrathin graphene piece in which less than 10 pieces of graphene are overlapped. 
     
     
         16 . The ultrathin graphene piece according to  claim 15 , wherein a hole(s) is formed in the graphene. 
     
     
         17 . The ultrathin graphene piece according to  claim 16 , wherein the diameter of the hole is 1 nm to 20 nm. 
     
     
         18 . The ultrathin graphene piece according to  claim 15 , wherein modifying molecules of any of a carbonyl group, a carboxyl group, or a hydroxyl group are not bound to the graphene. 
     
     
         19 . A capacitor, comprising:
 two electrodes; and   electrolytic solution impregnated layer which is disposed between the electrodes,   wherein the electrodes are electrodes which are made by molding powder comprising the ultrathin graphene piece according to  claim 15  in a plate shape.   
     
     
         20 . The capacitor according to  claim 19 , wherein a carbon nanotube is dispersed in the electrodes. 
     
     
         21 . A method of manufacturing capacitor, comprising:
 molding powder comprising the ultrathin graphene piece according to  claim 15  by filtering, washing, and drying a solution, in which the powder comprising the ultrathin graphene piece is dispersed, in a plate shape; and   manufacturing a capacitor by using the plate-shaped powder comprising the ultrathin graphene piece as an electrode.   
     
     
         22 . The method of manufacturing capacitor according to  claim 21 , wherein, in the step of molding the powder comprising the ultrathin graphene piece in a plate shape, a carbon nanotube is dispersed in the solution.