Preparation and Sodium Storage Performance of Soft Carbon‐Deposited Coconut Shell‐Derived Carbon Materials

ABSTRACT Activation treatment effectively enriches hard carbon anodes’ sodium storage sites and improves their capacity, but increases material defects and specific surface area, impairing initial Coulombic efficiency. Using coconut shells as raw material, this study modified activated coconut shell‐based hard carbon via pitch carbon deposition combined with high‐temperature carbonization, investigating carbon deposition's effect on hard carbon structure and the structure–electrochemical performance relationship. The research findings indicate that pitch deposition on the hard carbon surface effectively reduces surface pores and defects in coconut shell‐derived carbon. As the deposition mass increases, both specific surface area and micropore quantity progressively decrease, leading to a significant improvement in the initial Coulombic efficiency of the electrode material. When the pitch carbon deposition content reaches 1.5 wt%, the obtained sample CYK1.5 exhibits an interlayer spacing of 0.370 nm and a specific surface area of 4.160 m2 g −1 . CYK1.5 demonstrates an initial Coulombic efficiency of 80.6% and a reversible capacity of 354 mAh g −1 at a current density of 50 mA g −1 . After 200 cycles at 1000 mA g −1 , it maintains a discharge specific capacity of 243 mAh g −1 , exhibiting excellent cycling stability and rate capability.