Oxygen‐Driven Molecular Reconfiguration in Coal‐Derived Hard Carbon Anodes for High‐Performance Sodium‐Ion Batteries

ABSTRACT Hard carbon (HC) has emerged as a promising anode material for sodium‐ion batteries (SIBs), however, it suffers from low specific capacity and inferior initial Coulombic efficiency (ICE). Herein, an oxygen‐driven molecular reconfiguration strategy is proposed to strengthen reversible Na + storage in HC through synergistic alkali activation and pre‐oxidation. The oxygen functional groups on the surface promote the reconstruction of sp 2 ‐carbon within the highly cross‐linked amorphous macromolecular coal precursor, thereby enabling the coal‐based HC featuring with expanded interlayer spacing, increased pseudo‐graphitic and closed‐pore domains. This effectively facilitates the Na + transport kinetics and stable Na + (de)intercalation of HC, simultaneously suppressing the electrolyte decomposition. The resultant HC delivers a high reversible capacity of 317.4 mAh g −1 at 25 mA g −1 , an impressive ICE of 88.05%, excellent rate capability of 253.42 mAh g −1 at 1000 mA g −1 , and a superior capacity retention of 82.92% over 1000 cycles. This work highlights the crucial role of oxygen‐driven microstructural reconstruction in durable sodium storage of HC.