Electrochemical production of graphene sheets directly from graphite mineral

Patent metadata

Field	Value
Publication number	US-2017260637-A1
Application number	US-201614998944-A
Country	US
Kind code	A1
Filing date	Mar 9, 2016
Priority date	Mar 9, 2016
Publication date	Sep 14, 2017
Grant date	—

Abstract

A method of producing graphene sheets directly from graphite mineral (graphite rock) powder, comprising: (a) forming an intercalated graphite compound by an electrochemical intercalation procedure conducted in an intercalation reactor, containing (i) a liquid solution electrolyte comprising an intercalating agent and a graphene plane-wetting agent dissolved therein; (ii) a working electrode that contains the graphite material powder as an active material; and (iii) a counter-electrode, and wherein a current is imposed upon the working electrode and counter electrode at a current density sufficient for effecting electrochemical intercalation of the intercalating agent and/or wetting agent into interlayer spacing, wherein the wetting agent is selected from melamine, ammonium sulfate, sodium dodecyl sulfate, Na(ethylenediamine), tetraalkyammonium, ammonia, carbamide, hexamethylenetetramine, organic amine, poly(sodium-4-styrene sulfonate), or a combination thereof; and (b) exfoliating and separating the intercalated graphite compound using ultrasonication, thermal shock exposure, and/or a mechanical shearing treatment to produce graphene sheets.

First claim

1 . A method of producing isolated graphene sheets directly from a supply of graphite mineral powder containing therein hexagonal carbon atomic interlayers with an interlayer spacing, said method comprising:
(a) forming an intercalated graphite compound by an electrochemical intercalation procedure which is conducted in an intercalation reactor, wherein said reactor contains (i) a liquid solution electrolyte comprising an intercalating agent and a graphene plane-wetting agent dissolved therein; (ii) a working electrode that contains said graphite mineral powder as an active material in ionic contact with said liquid solution electrolyte; and (iii) a counter electrode in ionic contact with said liquid solution electrolyte, and wherein a current is imposed upon said working electrode and said counter electrode at a current density for a duration of time sufficient for effecting electrochemical intercalation of said intercalating agent and/or said wetting agent into said interlayer spacing, wherein said wetting agent is selected from melamine, ammonium sulfate, sodium dodecyl sulfate, sodium (ethylenediamine), tetraalkyammonium, ammonia, carbamide, hexamethylenetetramine, organic amine, pyrene, 1-pyrenecarboxylic acid, 1-pyrenebutyric acid, 1-pyrenamine, poly(sodium-4-styrene sulfonate), or a combination thereof; and (b) exfoliating and separating said hexagonal carbon atomic interlayers from said intercalated graphite compound using an ultrasonication, thermal shock exposure, mechanical shearing treatment, or a combination thereof to produce said isolated graphene sheets.

2 . The method of claim 1 , wherein multiple particles of said graphite mineral powder are dispersed in said liquid solution electrolyte, disposed in a working electrode compartment, and supported or confined by a current collector in electronic contact therewith, and wherein said working electrode compartment and said multiple particles supported thereon or confined therein are not in electronic contact with said counter electrode.

3 . The method of claim 2 , wherein said multiple particles are clustered together to form a network of electron-conducting pathways.

4 . The method of claim 1 , wherein said method is conducted intermittently or continuously and said supply of graphite mineral powder and said liquid solution electrolyte are provided into said reactor intermittently or continuously.

5 . The method of claim 2 , wherein said method is conducted intermittently or continuously and said supply of graphite mineral powder and said liquid solution electrolyte are provided into said working electrode compartment intermittently or continuously.

6 . The method of claim 1 , wherein said graphite mineral powder contains a proportion of layered graphite material in the range from 20% to 97% by weight.

7 . The method of claim 1 , wherein said graphite mineral powder contains a proportion of layered graphite material in the range from 30% to 90% by weight.

8 . The method of claim 1 , wherein said working electrode contains no other graphite material than said graphite mineral powder as an electrode active material to be intercalated.

9 . The method of claim 2 , wherein said graphite mineral powder in said working electrode compartment is dispersed in the liquid solution electrolyte at a concentration higher than 20% by weight.

10 . The method of claim 2 , wherein said graphite mineral powder in said working electrode compartment is dispersed in the liquid solution electrolyte at a concentration higher than 40% by weight.

11 . The method of claim 2 , wherein said graphite mineral powder in said working electrode compartment is dispersed in the liquid solution electrolyte at a concentration higher than 50% by weight.

12 . The method of claim 1 , wherein said mechanical shearing treatment comprises operating air milling, air jet milling, ball milling, rotating-blade mechanical shearing, or a combination thereof.

13 . The method of claim 1 , wherein the imposing current provides a current density in the range of 0.1 to 600 A/m 2 .

14 . The method of claim 1 , wherein the imposing current provides a current density in the range of 1 to 500 A/m 2 .

15 . The method of claim 1 , wherein the imposing current provides a current density in the range of 10 to 300 A/m 2 .

16 . The method of claim 1 , wherein said thermal shock exposure comprises heating said intercalated graphite to a temperature in the range of 300-1,200° C. for a period of 15 seconds to 2 minutes.

17 . The method of claim 1 , wherein said isolated graphene sheets contain single-layer graphene.

18 . The method of claim 1 , wherein said isolated graphene sheets contain few-layer graphene having 2-10 hexagonal carbon atomic interlayers or graphene planes.

19 . The method of claim 1 , wherein said electrochemical intercalation includes intercalation of both said intercalating agent and said wetting agent into the interlayer spacing.

20 . The method of claim 1 , wherein said intercalated graphite compound contains Stage-1, Stage-2, or a combination of Stage-1 and Stage-2 graphite intercalation compounds.

21 . The method of claim 1 , further comprising a step of re-intercalating said isolated graphene sheets using an electrochemical or chemical intercalation method to obtain intercalated graphene sheets and a step of exfoliating and separating said intercalated graphene sheets to produce single-layer graphene sheets using ultrasonication, thermal shock exposure, exposure to water solution, mechanical shearing treatment, or a combination thereof.

22 . The method of claim 1 , wherein said intercalating agent includes a species selected from a Brønsted acid selected from phosphoric acid (H 3 PO 4 ), dichloroacetic (Cl 2 CHCOOH), or an alkylsulfonic acid selected from methanesulfonic (MeSO 3 H), ethanesulfonic (EtSO 3 H), or 1-propanesulfonic (n-PrSO 3 H), or a combination thereof.

23 . The method of claim 1 , wherein said intercalating agent includes a metal halide.

24 . The method of claim 1 , wherein said intercalating agent includes a metal halide selected from the group consisting of MCl (M=Li, Na, K, Cs), MCl 2 (M=Zn, Ni, Cu, Mn), MCl 3 (M=Al, Fe, Ga), MCl 4 (M=Zr, Pt), MF 2 (M=Zn, Ni, Cu, Mn), MF 3 (M=Al, Fe, Ga), MF 4 (M=Zr, Pt), and combinations thereof.

25 . The method of claim 1 , wherein said intercalating agent includes an alkali metal salt selected from sodium perchlorate (NaClO 4 ), potassium perchlorate (KClO 4 ), sodium hexafluorophosphate (NaPF 6 ), potassium hexafluorophosphate (KPF 6 ), sodium borofluoride (NaBF 4 ), potassium borofluoride (KBF 4 ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF 3 SO 3 ), potassium trifluoro-metasulfonate (KCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide sodium (NaN(CF 3 SO 2 ) 2 ), sodium trifluoromethanesulfonimide (NaTFSI), bis-trifluoromethyl sulfonylimide potassium (KN(CF 3 SO 2 ) 2 ), a sodium ionic liquid salt, lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro-metasulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium (LiN(CF 3 SO 2 ) 2 ), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LiBF 2 C 2 O 4 ), lithium oxalyldifluoroborate (LiBF 2 C 2 O 4 ), lithium nitrate (LiNO 3 ), Li-Fluoroalkyl-Phosphates (LiPF 3 (CF 2 CF 3 ) 3 ), lithium bisperfl

Assignees

• Zhamu Aruna
• Jang Bor Z

Inventors

• Zhamu Aruna
• Jang Bor Z

Classifications

• C25D1/006 Primary

  Nanostructures, e.g. using aluminium anodic oxidation templates [AAO] · CPC title

• C01B31/0469

  Chemistry & Metallurgy · mapped topic

• C25D1/20

  Separation of the formed objects from the electrodes {with no destruction of said electrodes} · CPC title

• C01B2204/04

  Specific amount of layers or specific thickness · CPC title

• C01B2204/02

  Single layer graphene · CPC title