Revisiting the Enhancement Mechanism of Electrochemical Performance of Functional Atom‐Doped Hard Carbon in Potassium‐Ion Batteries

ABSTRACT Atomic doping is recognized as an effective strategy to enhance the electrochemical performance of hard carbon (HC) in potassium‐ion batteries. However, the comprehension of its influence on microstructure remains inadequately understood. Here, we investigate the synergistic effect of structural evolution and performance changes of HC, while comprehensively analyzing the strengthening mechanism of N/S co‐doping on potassium‐ion storage. N/S can serve not only as active sites for electrochemical redox reactions, but also expand the carbon interlayer spacing while regulating electronic properties, thereby improving diffusion kinetics. Remarkably, the introduction of N/S can adjust the curvature of graphitic microcrystallites, promoting the formation of closed pore structures, which contributes to the pore‐filling of quasi‐metallic potassium clusters. Multidimensional characterization techniques confirmed the “adsorption‐insertion/pore‐filling” mechanism for potassium storage in HC. This work establishes a design theoretical framework aimed at enhancing electrochemical performance, offering a theoretical foundation and a selection methodology for the advancement of high‐performance HC anode.