Commercial activated carbon as a novel precursor of the amorphous carbon for high-performance sodium-ion batteries anode

Amorphous carbon-based anode materials are considered as one of the most promising candidates for sodium-ion batteries (SIBs). However, there are two main barriers before large-scale industrialization, i.e. low initial coulombic efficiency (ICE) and high cost caused by low carbon yield of precursors. In this work, we report a novel commercial activated amorphous carbon-based anode synthesized through a facile-tailored strategy consisting of annealing and surface coating. The as-prepared amorphous carbon has a porous internal structure but a very low specific surface area (SSA) with a dense surface carbon layer. As an anode material for SIBs, the obtained amorphous carbon displays an outstanding electrochemical performance including a high reversible capacity of 391 mAh g−1 at a current density of 25 mA g−1 with a high ICE of 80%, and a superior cycling performance with a capacity retention of 97% after 100 cycles. The high ICE is mainly attributed to the denser surface carbon layer which suppresses the penetration of electrolyte and fully utilizes the internal porosity. The commercial availability, and the desirable properties make this novel amorphous carbon-based anode a promising candidate for SIBs.