N, S Co‐Doped Carbon Derived From Lignosulfonate Sodium Synergized With Bismuth for Enhanced Sodium‐Ion Storage

Developing high‐performance anode materials is crucial for advanced sodium‐ion batteries. Bismuth (Bi)‐based anodes offer high capacity but suffer from significant volume expansion. To address this, we synthesized Bi particles embedded within an N, S co‐doped porous carbon matrix (Bi@NSC‐ x ) using biomass‐derived sodium lignosulfonate. The optimal Bi@NSC‐600 electrode demonstrates exceptional performance with a high reversible capacity of 324.3 mAh g −1 at 0.1 A g −1 , outstanding rate capability (313.1 mAh g −1 at 20 A g −1 , 268.8 mAh g −1 at 50 A g −1 ), and remarkable long‐term stability (retaining 300.3 mAh g −1 after 4800 cycles at 1 A g −1 and 296.9 mAh g −1 after 5600 cycles at 5 A g −1 ). Moreover, a full cell with a Na 3 V 2 (PO 4 ) 3 cathode delivers 107.9 mAh g −1 at 0.5 C and maintains 84.4 mAh g −1 after 2300 cycles at 10 C. The superior performance stems from the synergistic effect in which the heteroatom‐doped carbon framework enhances conductivity and Na + adsorption, while its porous structure confines Bi particles, buffering volume changes and facilitating efficient ion/electron transport.