Hierarchical porous nitrogen-rich carbon nanospheres with high and durable capabilities for lithium and sodium storage

To improve the energy storage performance of carbon-based materials, considerable attention has been paid to the design and fabrication of novel carbon architectures with structural and chemical modifications. Herein, we report that hierarchical porous nitrogen-rich carbon (HPNC) nanospheres originating from acidic etching of metal carbide/carbon hybrid nanoarchitectures can be employed as high-performance anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The structural advantages of HPNC nanospheres are that the exceptionally-high content of nitrogen (17.4 wt%) can provide abundant electroactive sites and enlarge the interlayer distance (similar to 3.5 angstrom) to improve the capacity, and the large amount of micropores and mesopores can serve as reservoirs for storing lithium/sodium ions. In LIBs, HPNC based anodes deliver a high reversible capacity of 1187 mA h g(-1) after 100 cycles at 100 mA g(-1), a great rate performance of 470 mA h g(-1) at 5000 mA g(-1), and outstanding cycling stabilities with a capacity of 788 mA h g(-1) after 500 cycles at 1000 mA g(-1). In SIBs, HPNC based anodes exhibit a remarkable reversible capacity of 357 mA h g(-1) at 100 mA g(-1) and high long-term stability with a capacity of 136 mA h g(-1) after 500 cycles at 1000 mA g(-1).