Development of graphene-based materials for energy storage

Summary form only given. Energy is one of the most important issues in this century. With the rapid depletion of fossil fuel and increasingly worsened environmental pollution caused by vast fossil energy consumption, it is in a high demand to make efficient use of the present energy sources and to seek for renewable and clean energy sources. Therefore, research and development of new energy storage materials and devices are receiving worldwide concern and increasing research interest. Graphene, a unique two-dimensional carbon material, is predicted to be an excellent electrode material candidate for energy conversion/storage systems because of its high specific surface area, good chemical stability, excellent electrical and thermal conductivity as well as remarkably high mechanical strength and Young´s modulus. This talk will focus on the preparation and energy storage exporations of graphene-based materials. The graphene sheets with different number of layers and large lateral size were synthesized by chemical exfoliation and reduction. A simple method for the efficient reduction of graphene oxide (GO) films was developed, and the graphene films obtained have high electrical conductivity and maintain the integrity and flexibility of GO films at the same time. In particular, graphene-based materials were developed for electrochemical energy storage applications in lithium ion batteries and supercapacitors. It was found that synergetic effects between graphene nanosheets and metal oxides and conductive polymers can be used to develop energy storage materials with high capacity and capacitance, high rate capability and high cyclic performance. For example, graphene/polyaniline composite paper electrodes were prepared and showed a favorable tensile strength and a stable large electrochemical capacitance, which outperform many other currently available carbon-based flexible electrodes. Graphene/hydrous RuO₂ composites were developed for electrochemical capa- itor with high energy density, and graphene-anchored Co₃O₄ and graphene-wrapped Fe₃O₄ composites and other composite materials for next-generation lithium ion batteries were also investigated in detail.