Synergistic Regulation of Pore Architecture and Surface Interface in Bamboo-Derived Hard Carbon via Particle Size Control for Enhanced Sodium Storage Kinetics

Hard carbon (HC) is viewed as an excellent negative electrode for sodium-ion batteries due to its low cost and unique porous structure. Bamboo-derived hard carbon is regarded as an environmentally friendly and commercially viable option. Jet-milled fines, a byproduct in production, are usually dismissed. We propose a particle size blending strategy, reintroducing jet-milling fines into the carbonized primary particles to study their function in this work. Our results indicate that this method can enhance the electrochemical performance of hard carbon materials. The modified anode (HC-BF30) delivers higher slope and plateau reversible capacity. Rate capability and cycle stability are also enhanced in the modified anode. Structural analysis suggests that the reintroduced fines provide a richer mesoporous network for ions, improve the carbon framework’s graphitization for better electron flow, and lower surface oxygen content to stabilize the interface.