Single‐Atom Modification of Hard Carbon for Enhanced Coupled Ion‐Electron Transfer Toward Superior Plateau Kinetics in Sodium‐Ion Batteries

ABSTRACT Hard carbon (HC) is a promising anode material for sodium‐ion batteries, yet its rate capability remains limited by sluggish kinetics in the plateau region. Conventional modification strategies often focus solely on improving ion transfer (IT) while neglecting the accompanying electron transfer (ET) process. Herein, a single‐atom Mn decoration strategy is proposed to enhance the coupling of IT and ET (CIET). The incorporated Mn species not only enlarges the graphitic interlayer spacing to facilitate IT, but also establishes an optimized electron‐coupling network that significantly enhances ET efficiency both within the plane and across interfaces. Benefiting from the enhanced CIET, the resulting Mn decorated HC anode exhibits exceptional rate performance, retaining 80% of its capacity as the current density increases 20‐fold from 0.1 to 2 A g −1 , along with remarkable cycling stability (171.1 mAh g −1 after 2000 cycles at 1 A g −1 ) and excellent low‐temperature stability (84.9% capacity retention after 1000 cycles at ‐20°C). Through integrated in/ex situ characterizations and theoretical calculations, a coordinated “surface adsorption‐intercalation enrichment & quasi‐metallic conversion” storage mechanism was elucidated. This work transcends the conventional focus on IT by highlighting the critical role of enhanced CIET, offering valuable insights for developing advanced carbonaceous anodes toward high‐performance energy storage.