Electrochemical performance of graphene nanosheets and ceramic composites as anodes for lithium batteries

A nanocomposite anode material for lithium batteries is designed and fabricated by the insertion of graphite nanosheets (GNS) into the ceramic network of silicon oxycarbide (SiOC) ceramics for the development of structurally and electrochemically stable lithium batteries. The GNS forms a layered phase in the SiOC ceramic network from the self-assembly of graphite oxides (GO) introduced in a polysiloxane precursor through thermal transformations after pyrolysis. The composite anode (GNS/SiOC) exhibits an initial discharge capacity attaining 1141 mAh g−1. The discharging capacity decreases in the first eight cycles and stays at 364 mAh g−1 in the following cycles. This reversible discharging capacity is higher than that of a graphite reference (328 mAh g−1) and a SiOC monolithic. Correlating the discharge capacities to the material compositions and structures suggest that the interface between SiOC and GNS contributes to the enhanced capacity of the composite anode, in addition to those from GNS and SiOC. Further increasing the electrochemical performance is possible by the increase of the amount of GNS in the composite.