Progress in macroscopic preparation of porous graphene

Graphene prepared in 2004 by British scientists Andrei Jem and Kostya Novoovov, etc., has excellent electrical conductivity and a large theoretical specific surface area in electrochemical energy storage. Broad application prospects. However, due to the action of the π-π bond and van der Waals force, graphene is easily self-agglomerated to form a graphite structure. Therefore, the macro-preparation and structural regulation of graphene is still a difficult problem to study.

Recently, the Ma Yanwei group of the Institute of Electrical Engineering of the Chinese Academy of Sciences has made significant progress in the macro-preparation of porous graphene. By using a new method-combustion quenching technology, the magnesium metal strip is ignited in carbon dioxide gas and quenched in situ in ammonium bicarbonate solution. A graphene material having a high quality and containing a large amount of mesoporous structure was successfully prepared.

Under the new method, 25 g of magnesium can produce about 1 g of graphene. The graphene has a mesoporous order, a specific surface area of ​​up to 756 m 2 /g, a mesoporous size distribution of about 2 nm and 7 nm, and a pore volume of 1.5 cm 3 /g ( FIG. 1 ). The mesoporous ordered graphene materials are used in supercapacitors and lithium ion batteries respectively (Fig. 2). The energy density of graphene-based symmetric supercapacitors under ionic liquid electrolyte is as high as 51.5Wh/kg, corresponding power. The density is 1 kW/kg; when the power density is 20 kW/kg, the energy density is maintained at 23.1 Wh/kg. The lithium ion battery anode material was maintained at 570 mAh/g after circulating for 250 weeks at a current density of 0.2 A/g, and the above values ​​were all based on the electrode material.

The method is a template-free self-grown mesoporous ordered structure graphene, which is simple in operation, low in cost, environmentally friendly, and has high quality and high yield of graphene, and has applied for a national invention patent. Related results were published in the June issue of Chemistry and Sustainability, Energy and Materials (ChemSusChem, 2013, 6, 1084, IF=6.8).

This work was supported by the Beijing Municipal Science and Technology Commission and the Chinese Academy of Sciences project.

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