An oxygen doped porous hard carbon derived from durian shell for high-performance sodium ion storage

Hard carbon is one of the most promising anodes for sodium ion batteries (SIBs) because of its low charge/discharge voltage platform, high specific surface area and higher layer spacing. However, the disadvantages of its unsatisfactory sodium storage capacity and high cost owing to low carbonization yield of precursors frustrate its practical applications. In this paper, we have developed a porous hard carbon derived from durian shell (DSHC) synthesized via acid washing and secondary calcination by adjusting carbonization temperature. As an anode for SIBs, the durian shell carbonization at 700 °C (DSHC700) with suitable graphite layer spacing (0.382 nm) delivered a high capacity of 297.2 mAh g^-1 after 100 cycles at 25 mA g^-1. The excellent electrochemical performance is attributed to the moderate interlayer spacing due to oxygen doping, and the natural rich porous structure which can increase the active site of Na⁺, shortened the diffusion distance of Na⁺, and promoted the transport of electrolyte. This study could provide a simple method to prepare high performance anodes for SIBs using durian shell as carbon source, and this design strategy could be extended to other biomass-based carbon materials.