Fluorinated N,P co‐doped biomass carbon with high‐rate performance as cathode material for lithium/fluorinated carbon battery

Abstract Lithium/fluorinated carbon (Li/CF x ) batteries are greatly limited in their applications mostly due to poor rate performances. In this study, N,P co‐doped biomass carbon was synthesized using melamine and phytic acid as doping sources, and the resulting product was then utilized as a precursor for CF x . The resulting fluorinated biomass carbon has a high degree of fluorination, exceeding the specific capacity of commercial fluorinated graphite while also demonstrating exceptional performance at high discharge rates. During the fluorination process, N,P‐containing functional groups were removed from the crystalline lattice in the basal plane. This facilitates the formation of a defect‐rich carbon matrix, enhancing the F/C ratio by improving the fluorinated active sites and obtaining more highly active semi‐ionic bonds. Additionally, the abundant defects and porous structure promote Li + diffusion. Density functional theory calculations indicated that doping modification effectively reduces the energy barrier for Li + migration, enhancing Li + transport efficiency. The prepared CF x delivers material with a maximum specific capacity of 919 mAh·g −1 , while maintaining a specific capacity of 702 mAh·g −1 at a high discharge current density of 20C (with a capacity retention rate of 76.4%). In this study, fluorinated N,P co‐doped biomass carbon, exhibiting ultrahigh capacity and high‐rate performance, was prepared for the first time, which can potentially advance the commercialization of CF x .