▎ 摘　　要

NOVELTY - Producing isolated graphene sheets having average thickness smaller than 30 nm directly from layered graphite material having hexagonal carbon atomic interlayers with interlayer spacing, comprises: (a) forming alkali metal ion-intercalated graphite by electrochemical intercalation procedure which is conducted in intercalation reactor; and (b) exfoliating and separating hexagonal carbon atomic interlayers from alkali metal ion-intercalated graphite compound using ultrasonication, thermal shock exposure and/or exposure to water solution with mechanical shearing to give isolated graphene sheets. USE - The method is useful for producing isolated graphene sheets having average thickness smaller than 30 (preferably 10) nm directly from layered graphite material having hexagonal carbon atomic interlayers with interlayer spacing (claimed). ADVANTAGE - The method: does not involve the evolution of undesirable species e.g. sulfuric or nitric acids which are common by-products of exfoliating conventional sulfuric or nitric acid-intercalated graphite compounds; and provides few-layer graphene and/or single-layer graphene only with higher than 80%, preferably higher than 90% yield. DETAILED DESCRIPTION - Producing isolated graphene sheets having an average thickness smaller than 30 (preferably 10) nm directly from a layered graphite material having hexagonal carbon atomic interlayers with an interlayer spacing, comprises: (a) forming an alkali metal ion-intercalated graphite compound by an electrochemical intercalation procedure which is conducted in an intercalation reactor, where the reactor contains (i) a liquid solution electrolyte, comprising an alkali metal salt dissolved in an organic solvent, in physical contact with both an anode and a cathode and the layered graphite material contains milled graphite rock or graphite mineral dispersed in the liquid solution electrolyte at a concentration higher than 20 wt.%, (ii) an anode that contains the layered graphite material as an active material in ionic contact with the liquid solution electrolyte, and (iii) a cathode in ionic contact with the liquid solution electrolyte, where the current is imposed upon the cathode and the anode at a current density for a duration of time for effecting the electrochemical intercalation of alkali metal ions into the interlayer spacing and the organic solvent is 1,3-dioxolane, 1,2-dimethoxyethane, tetraethylene glycol dimethyl ether, poly(ethylene glycol)dimethyl ether, diethylene glycol dibutyl ether, 2-ethoxyethyl ether, sulfone, sulfolane, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl propionate, methyl propionate, gamma -butyrolactone, acetonitrile, ethyl acetate, propyl formate, methyl formate, toluene, xylene, methyl acetate, fluoroethylene carbonate, vinylene carbonate, allyl ethyl carbonate and/or a hydrofluoroether; and (b) exfoliating and separating the hexagonal carbon atomic interlayers from the alkali metal ion-intercalated graphite compound using ultrasonication, thermal shock exposure and/or exposure to water solution with a mechanical shearing treatment to produce the isolated graphene sheets.