A graphitic foam framework with hierarchical pore structure as self-supported electrodes of Li-O₂ batteries and Li ion batteries

Hydrothermal self-assembly is a highly efficient and low cost method to prepare graphitic foam from graphene oxides; however, the self-assembly frameworks usually do not have controllable pore structures because of the spontaneous process. In this paper, a hydrothermal synthesis assisted by ammonium peroxo-polymolybdate [(NH₄)₂Mo₂O₁₁] tailoring to fabricate graphitic foam is presented. The foam possesses pore structures which can be controlled by adjusting the rate of charge in the hydrothermal experiments. Furthermore, the foam obtained from a definite rate of charge [(NH₄)₂Mo₂O₁₁ : graphene oxide is 1 : 2 in weight] has a hierarchical pore structure and a through-hole net. In electrochemical energy storage, such unique features are beneficial for providing efficient mass transport as well as abundant, accessible active sites. The graphitic foam was tested for use as self-supported electrodes of Li-O₂ batteries (LOBs) and Li ion batteries (LIBs) without any metallic current collectors or organic binders, and the foam frameworks exhibited remarkable lithium ion storage properties in both of the two batteries (e.g., 5500 mA h g^-1 at 0.2 A g^-1 as LOB cathodes and 250 mA h g^-1 at 50 A g^-1 as LIB anodes).