Recent Developments and Future Prospects of Transition Metal Compounds as Electrode Materials for Potassium-Ion Hybrid Capacitors

Abstract

Potassium-ion hybrid capacitors (PIHCs) have attracted considerable attention as emerging electrochemical energy storage devices for simultaneously achieving high energy and power density, which the key to success is the development of compatible electrode materials for both battery-type anode and capacitive cathode. Among numerous electrode materials, transition metal compounds (including oxides, chalcogenide, carbides, and nitrides) show great potential owing to their high theoretical capacity to achieve high energy density, but their sluggish reaction kinetics restrict the attainable power density. Hence, in the last few years, different strategies are proposed to improve the performance of transition metal compounds as electrode materials for PIHCs, and significant progress is achieved. Herein, this review outlines recent advances of employing transition metal compounds as electrode materials for PIHCs. The performance and challenges of different transition metal compounds are discussed in detail. Finally, the future prospects of practical applications of transition metal compounds in PIHCs are briefly discussed.