Fluorine Doping Modulating Pore Structure and Adsorption Capability of Carbon Matrix Boosting Potassium Storage Performance of Red Phosphorus Anode

Abstract The application of alloying‐typed red phosphorus (red P) anode in potassium‐ion batteries (KIBs) with ultra‐high theoretical capacity is hindered by the limited capacity and fast capacity decay due to poor electronic conductivity and huge volume change. Herein, a facile and efficient strategy of fluorine (F) doping is innovatively developed to modulate the pore structure of carbon matrix (F‐CNS) to encapsulate red P with enhanced potassium storage capability. Theoretical calculations reveal that F doping induces additional defects within the carbon layer, which facilitates P₄ molecules embedding into the F‐doping‐induced micropores, enhances the adsorption ability toward K atoms and P₄ molecules, and improves electrochemical kinetics assisted with more charge transfer obtained from the electron density difference, thus enabling robust potassium storage capability for such unique Red P@F‐CNS anode. Accordingly, the Red P@F‐CNS anode demonstrates outstanding cycling stability (90% capacity retention after 800 cycles at 2A g⁻¹), and the potassium‐ion full cell (Red P@F‐CNS//KFeHCF) exhibits exceptional long‐term cycling performance (129 mAh g⁻¹ after 2500 cycles at 5 A g⁻¹ with only 0.014% decay per cycle). In situ characterizations confirm the superior structural integrity of the carbon‐based matrix. This study offers a rational design principle for engineering high‐performance carbon‐supported alloying‐typed anodes for KIBs.