Unraveling Synergistic Regulation Mechanism in Nitrogen/Sulfur Co‐Doped Biomass‐Derived Hard Carbon Toward Durable Sodium‐Ion Battery Anodes

Hard carbon (HC) materials featuring well‐defined short‐range ordered architectures have emerged as promising anode materials for sodium‐ion batteries (SIBs). Nevertheless, due to the limited diffusion rate of sodium ions within the carbon structure, the rate capability of hard carbon at high current densities and long‐term cycling stability remains a challenge. Herein, an innovative nitrogen/sulfur co‐doping strategy is developed for loofah‐derived hard carbon (LHC‐N‐S), synergistically regulating the electron defect and spatial structure. The synergistic charge regulation is attributed to the introduction of N atoms for ion adsorption and the improvement of electron conductivity. The spatial structure regulation mainly comes from the S doping to optimize the layer spacing and pore size, which facilitates the rapid ion diffusion kinetics. The obtained LHC‐N‐S anodes maintain a high reversible specific capacity (317.5 mAh g −1 at 0.1 C) and ultralong lifespan (76% retention after 2000 cycles). Through the correlation analysis of the structural parameters and the Na + storage performance, the N/S co‐doping mechanism is further clarified. This work provides deep insights into the design of high‐performance biomass‐derived hard carbon anodes for SIBs by leveraging the synergistic charge and space regulation through heteroatom doping, paving the way for the development of durable and sustainable sodium‐ion battery technologies.