A distinctive edge-graphited hard carbon for advanced sodium-ion batteries

The commercialization of sodium-ion batteries (SIBs) as an effective alternative to lithium-ion batteries (LIBs) has garnered considerable attention. Among the various anodes for SIBs, hard carbon (HC) with expanded carbon layer spacing is the most promising candidate for commercialization. However, the intricate structure of HC can impact the initial coulombic efficiency (ICE) and cycling performance of the cell, potentially resulting in suboptimal capacity and rate capabilities. Here we find that the waste Camellia semiserrata shell (CSshell) can serve as a precursor for biomass-derived HC material, featuring unique edge-graphitized carbon layer structures formed through direct carbonization, distinct from conventional reported HC structures. Such an edge-graphitized HC material exhibits an exceptional initial reversible capacity of 320.06 mA h g-1 at a current density of 50 mA g-1 and a capacity retention of 93.7% after 1200 cycles at 500 mA g-1. The identification of the edge-graphited HC material, obtained from the waste CSshell, suggests a promising contender for low-cost and eco-friendly anode materials for SIBs.