A High Capacity and Working Voltage Potassium‐Based Dual Ion Batteries

Abstract

Potassium‐based dual ion batteries (KDIBs) have attracted significant attention owing to high working voltage, high safety, low processing cost, and environmental friendliness. Nevertheless, one great challenge for practical KDIBs is to develop suitable anode materials with high specific capacity. Herein, we report an architecture of hierarchically porous antimony nanoparticles/carbon nanofibers (HPSbCNFs) as flexible, free‐standing anode for high‐performance KDIBs. The HPSbCNFs with hierarchically porous structure, and high‐content nitrogen doping, not only offer sufficient free space to tolerate the repetitive volume expansion of Sb nanoparticles during long‐term cycling, but also greatly facilitate the transport of electrons and ions within electrode, ensuring high material utilization ratio. Thus, the KDIBs, constituted by HPSbCNFs‐700 (calcined at 700 °C) anode and graphite cathode, exhibited a high reversible capacity of 440 mAh g−1with high discharge medium voltage of 4.5 V at a specific current of 200 mA g−1(the highest capacity for all KDIBs normalized by the mass of the anode), and excellent cyclic life. Outstanding electrochemical reversibility of the KDIBs was further demonstrated byex situXRD,ex situRaman spectrum, and HRTEM. These results suggest the as‐designed HPSbCNFs‐700 with high‐capacity and long‐term cycling stability is a promising anode material for high‐performance KDIBs.