From Waste to Power: Transforming Coal Gasification Slag into High-Performance Sodium-Ion Battery Anodes via Nanofiber Engineering and Presodiation

Coal gasification slag (CGS), which contains a significant amount of unburnt carbon residue, exhibits favorable conductivity and structural stability, making it a promising candidate as an anode material for sodium-ion batteries (SIBs). However, its high specific surface area and low degree of graphitization limit its sodium storage performance. To broaden the application of CGS, enhance the availability of carbon-based anode materials for SIBs, and reduce costs, this study proposes a synergistic strategy combining carbon nanofiber formation and presodiation to improve the sodium storage performance of coal gasification slag. After treatment, the residual carbon in the gasification slag achieves a discharge specific capacity of 247.07 mAh/g after 260 cycles at a current density of 0.05 A/g. To further enhance the initial Coulombic efficiency (ICE) and specific capacity of the electrode material, presodiation is employed. The modified material (RC-CNF-800-15) delivers a specific capacity of 345.34 mAh/g and an ICE of 35.78%. In summary, this study utilizes CGS as a raw material, employs a combined approach of fibrillation and presodiation, and modifies the sodium storage properties of the slag-derived carbon, thereby improving its electrochemical performance. This strategy not only opens avenues for the application of coal gasification slag but also expands the sources of anode materials for SIBs.