Oxygen/Fluorine Dual-Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage

Carbon-based materials are promising anodes for potassium-ion batteries (PIBs). However, due to the significant volume expansion and structural instability, it is still a challenge to achieve a high capacity, high rate and long cycle life for carbonaceous anodes. Herein, oxygen/fluorine dual-doped porous carbon nanopolyhedra (OFPCN) is reported for the first time as a novel anode for PIBs, which exhibits a high reversible capacity of 481 mA h g(-1) at 0.05 A g(-1) and excellent performance of 218 mA h g(-1) after 2000 cycles at 1 A g(-1) with 92% capacity retention. Even after 5000 robust cycles at 10 A g(-1) with charging/discharging time of around 40 s, an unprecedented capacity of 111 mA h g(-1) is still maintained. Such ultrafast potassium storage and unprecedented cycling stability have been seldom reported in PIBs. Quantitative kinetics analysis reveals that both diffusion and capacitance processes are involved in the potassium storage mechanism. Density functional theory calculations demonstrate that the O/F dual-doped porous carbon promotes the K-adsorption ability and can absorb multiple K atoms with slight structural distortion, which accounts for the high specific capacity, outstanding rate capability, and excellent cycling stability of the OFPCN anode.