Ultralong cycle life sodium-ion battery anodes using a graphene-templated carbon hybrid

Hard carbons have been extensively investigated as anode materials for sodium-ion batteries due to their disordered structure and large interlayer distance, which facilitates sodium-ion uptake and release. Herein, we report a graphene-templated carbon (GTC) hybrid via a facile two-step strategy involving a graphene oxide-directed self-assembly process and subsequent pyrolysis treatment. When evaluated as an anode material for sodium-ion batteries, the GTC electrode exhibits ultralong cycling stability and excellent rate capability. A reversible capacity of 205 mA h g^-1 and more than 92% capacity retention were achieved after 2000 cycles at a current density of 200 mA g^-1. Even at 10 A g^-1 a high reversible capacity of 45 mA h g^-1 can be obtained. The superior electrochemical performance is due to the strong coupling effect between graphitic nanocrystallites and the graphene template and the large interlayer distance of the graphitic nanocrystallites, both of which can not only effectively relieve the sodiation-induced stress and preserve the electrode integrity during cycling but also promote the electron and sodium-ion transport.