METHOD AND APPARATUS FOR THE EXPANSION OF GRAPHITE
In a first implementation, a method for exfoliation of graphene flakes from a graphite sample includes compressing a graphite sample in an electrochemical reactor and applying a voltage between the graphite sample and an electrode in the electrochemical cell.
1 . A method for exfoliation of graphene flakes from a graphite sample, the method comprising:
compressing a graphite sample in an electrochemical reactor; and
applying a voltage between the graphite sample and an electrode in the electrochemical cell.
2 . The method of claim 1 , wherein compressing the graphite sample comprises:
pressing the graphite against an electrode member using a moveable ceramic membrane, wherein the ceramic membrane is permeable to the electrolyte.
3 . The method of claim 1 , further comprising annealing hydrogenated graphene flakes at 500 to 800° C. to yield graphene flakes.
4 . The method of claim 1 , wherein the electrode member is a cathode.
5 . The method of claim 4 , wherein the graphite sample is in electrical contact with a boron-doped diamond cathode member.
6 . The method of claim 1 , wherein the electrolyte comprises propylene carbonate and 0.1 M tetrabutylammonium hexafluorophosphate.
7 . The method of claim 1 , wherein the applied voltage is −5 V to −100 V.
8 . The method of claim 1 , further comprising varying a force that compresses the graphite sample.
9 . The method of claim 8 , wherein varying the force comprises reducing a pressure pressing the graphite sample against the cathode member after 2-3 hours of applied voltage at −60 V.
10 . The method of claim 1 , further comprising pelletizing the graphite sample.
11 . The method of claim 1 , wherein the voltage is applied for a total of 24 hours.
12 . An apparatus for the exfoliation of graphite, the apparatus comprising:
an electrochemical reactor;
electrodes comprising
an anode;
a cathode member;
a graphite sample; and
a compression apparatus configured to compress the graphite sample during an exfoliation reaction.
13 . The apparatus according to claim 12 , wherein the compression apparatus is configured to press the graphite sample against an electrode.
14 . The apparatus according to claim 13 , wherein the electrode is the cathode member.
15 . The apparatus according to claim 12 , wherein the graphite sample is free from binder.
16 . The apparatus according to claim 12 , further comprising at least two anodes.
17 . The apparatus according to claim 14 , wherein the cathode member comprises boron-doped diamond.
18 . The apparatus according to any one of claim 14 , wherein the cathode member comprises a metal film.
19 . The apparatus according to claim 12 , wherein the apparatus further comprises an electrolyte solution.
20 . The apparatus according to claim 19 , wherein the electrolyte solution comprises anhydrous propylene carbonate.
21 . The apparatus according to claim 19 , wherein the electrolyte solution further comprises 0.1 M tetrabutylammonium hexafluorophosphate.
22 . The apparatus of any one of claim 12 , wherein the compression apparatus comprises:
a ceramic membrane.
23 . The apparatus of claim 22 , wherein:
the ceramic membrane is disposed in a membrane press; and
the membrane press comprises
one or more rods, and
one or more force application mechanisms configured to apply force to the rods.