Due to its high-voltage capability and large surface area with high conductivity, graphene can be a promising electrode material in various electrochemical energy devices, such as Li-ion battery, electrochemical capacitor and fuel cells. Compared with the application as graphene film in electronics devices, the application as electrode material requires large amount of graphene bulk. However, the development of a scalable graphene production method remains an unresolved challenge. Although the exfoliation method of graphene from graphite via acid oxidation is a generally-used scalable method for graphene production, oxygen functional groups and defects introduced during exfoliation cannot be completely removed and degrade the excellent graphene properties, such as thermal/electrical conductivity. To develop the mass production method for high-quality graphene for the emerging energy applications, we have investigated facile graphene production using supercritical fluid (SCF). In this method, graphene is exfoliated from graphite immersed in SCF without acid oxidation. It is suggested that because of the high penetration ability of SCF, solvent molecules (ex. Ethanol, DMF and NMP) in supercritical condition diffuse between the graphene layers in graphite and expand the interlayer distance. Therefore, in this process, during exfoliation of graphene, the introduction of undesired defects and functional groups doesn't occur. Moreover, we revealed that that intermittent heating and cooling is an effective procedure for exfoliation. By using the circulating flow system, the high conversion rate above 30% from graphite to less than 4-layers-thick graphene was achieved. This developing scalable and efficient production method for high-quality graphene can contribute to understanding electrochemical characteristics of graphene devices. Moreover, the usage of produced graphene as a starting material will facilitate the precise control of graphene properties by chemical modification and the improvement of electrochemical energy devices.

High-throughput production of graphene using supercritical fluid for energy applications

248th National Meeting (2014)

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