High-performance, three-dimensional and porous K₃V₂(PO₄)₃/C cathode material for potassium-ion batteries

K3V2(PO4)(3) (KVP) can be employed as a potential cathode material for potassium-ion batteries owing to its high theoretical capacity (106 mA h g(-1)). However, the inherently poor electronic conductivity of KVP severely restricts its electrochemical performance. In this study, a citric-acid-assisted sol-gel method was used to synthesise a three-dimensional porous-framework-supported K3V2(PO4)(3)/C composite material. A convenient three-dimensional channel and a conductive carbon skeleton were formed in a porous structure between K3V2(PO4)(3) particle covered by in situ carbon layers. Among the fabricated composites, K3V2(PO4)(3)/C prepared at 800 degrees C exhibited an optimal discharge specific capacity (76 mA h g(-1) at 20 mA g(-1)), superior rate performance (discharge capacity of 37 mA h g(-1) at 400 mA/g), and cycling stability (discharge capacity of 43 mA h g(-1) after 100 cycles at 200 mA g(-1)). The improved performance was attributed to the three-dimensional porous conductive structure. This structure can improve the electrical conductivity, increase the electrode/electrolyte contact surface area, accelerate the electrode kinetics, and enhance the structure stability. The strategy involving the synthesis of three-dimensional porous structures may enable the development of high-performance potassium-ion batteries.