Superior lithium/potassium storage capability of nitrogen-rich porous carbon nanosheets derived from petroleum coke†
Tremendous attention has been paid to carbon-based anodes for lithium-ion and potassium-ion batteries. Nevertheless, conferring high energy storage properties using carbon-based anodes is still challenging. In this work, petroleum coke-based nitrogen-doped porous carbon nanosheets (N-PCSs) were prepared using carbon nitride (g-C3N4) as both a template and nitrogen source and tested as advanced anode materials. The as-obtained N-PCSs constructed through an in situ solid-state approach possess both high capacity and excellent cycling stability. High capacities were obtained for Li-ion and K-ion batteries (407 mA h g−1 after 500 cycles at 3720 mA g−1 and 206 mA h g−1 after 300 cycles at 1000 mA g−1, respectively); these are some of the best capacities for carbon-based electrode materials and could be ascribed to the unique microstructure of the anodes, i.e., nanosheet morphology, developed porosity, ultrahigh nitrogen doping, and a high level of disorder. Meanwhile, this study represents a milestone for high-value utilization of petroleum coke and other kinds of heavy oil.