Molecular‐Level Design of Asphalt‐Derived Hard Carbon with Enhanced Ion/Electron Transport for High‐Rate Sodium‐Ion Batteries

ABSTRACT Asphalt is an attractive precursor for hard carbon anodes in sodium‐ion batteries owing to its low cost and excellent structural consistency. However, conventional oxidative strategies, commonly employed for converting asphalt into hard carbon, inevitably distorts the carbon framework, disrupting electronic continuity and Na⁺ diffusion, thereby limiting rate capability. Herein, an integrated molecular‐level strategy is developed by coupling controlled oxidative crosslinking with simultaneous nitrogen modulation, enabling rapid electron/ion transport and delivering outstanding electrochemical performance, as validated in Ah‐level cylindrical cells. Combined with in situ characterizations and theoretical calculations, we uncover that synergistic graphitic and pyrrolic nitrogen species markedly enhance structural stability and charge transport—with the electronic conductivity reaching 41.9 S cm −1 (1.5 × higher) and ionic conductivity up to 0.87 mS cm −1 (1.4 × higher)—while inducing the formation of a thin, NaF‐rich solid electrolyte interface that collectively promotes ultrafast Na + migration and long‐term stability. As a result, the modulated hard carbon achieves a high capacity of 361.8 mA h g −1 , excellent rate capability (190.3 mA h g −1 at 5.0 A g −1 ), and superior cycling stability. When assembled into 18650 cylindrical cells, it delivers energy density of 106.7 Wh kg −1 , retaining 83.8% capacity after 1000 cycles at 1C/10C, highlighting its strong practical potential.