All-redox solid-state supercapacitor with cobalt manganese oxide@bimetallic hydroxides and vanadium nitride@nitrogen-doped carbon electrodes

Engineering a new class of electrode materials by combining different active components is crucial to boost the energy storage capacity of current supercapacitors. In this study, multicomponent cobalt manganese oxide@bimetallic nickel-cobalt hydroxides (CoMn₂O₄@NiCo-OH) and vanadium nitride@nitrogen-doped carbon (VN@NC) structures are directly grown on carbon cloth and a hybrid solid-state supercapacitor (HSSC) is designed. The integral design of the unique CoMn₂O₄@NiCo-OH and VN@NC electrodes offers a highly porous nanostructure, active surface sites, and facile pathways for fast electronic and ionic transportation, thereby speeding up the electrochemical reactions. As a battery-type material, CoMn₂O₄@NiCo-OH electrode achieves high specific capacity of 349.0 mA h g⁻¹ at 1 mA cm⁻², good rate capability, and excellent cyclic durability. Similarly, VN@NC electrode presents excellent electrochemical features in the negative potential side with specific capacity of 113.4 mA h g⁻¹ at 2 mA cm⁻². The HSSC device demonstrates a high specific energy of 68.83 W h kg⁻¹ at a specific power of 2048 W kg⁻¹ and an excellent cyclic durability. The overall findings present a sustainable approach for developing hierarchical multicomponent core-shell energy materials with a high capacity for the construction of future energy-storage devices.