Realizing superior redox kinetics of metal-metal carbides/carbon coordination supported heterointerface for stable solid-state hybrid supercapacitor

The family of transition metal carbides (TMCs) has been rapidly expanded since the discovery of the Ti3C2 MXenes for various energy-orientated applications. The metal-like electronic conductivity of TMCs is suitable for getting the high-power capability for the energy storage system. However, the practical applications of TMCs are still overwhelming owing to their poor redox activity and limited energy-storing capacity. Herein, a highly conductive yet redox-active metallic nickel–cobalt intertwined cobalt–nickel carbide@carbon (NiCo-CNC@C) nanoarchitecture cathode was developed for the high-performance hybrid supercapacitor. Experimental analysis reveals that the incorporation of metals in metal carbide enhances the electronic states, minimizes the barriers in reaction kinetics, and improves redox-active species, thus boosting electrochemical performance. Accordingly, the obtained NiCo-CNC@C-700 with optimized material composition presents a high specific capacity of 194.8 mAh/g at 1 A/g with exceptional rate capability (76.8 % at 20 A/g). Moreover, a hybrid solid-state supercapacitor assembled with NiCo-CNC@C-700 and WO3@C as positive and negative electrodes delivers a specific energy density of 72.6 Wh kg−1 at specific power of 1780 W kg−1 and superior cycle stability. The proposed approach of metals blended with metal carbides proves their feasibility by regulating the redox reactivity of materials to encompass their practices in upcoming energy storage applications.