Investigation on mesoporous bimetallic tungstate nanostructure for high-performance solid- state supercapattery

Abstract Identification of electrode materials with excellent specific capacity and energy density are significant factors for the development of high-performance supercapattery device. Transition metal tungstate is an emerging electroactive material for supercapattery due to its excellent electrical conductivity and electrochemical properties. Herein, the mesoporous Ni(1−x)Co(x)WO4 nanomaterials were synthesized by a one-step hydrothermal method as an anode material for supercapattery. The apparent discrepancy in mesoporous structures was incited by varying the stoichiometric ratio of Ni/Co in the Ni(1−x)Co(x)WO4 system which lead to an increase in the electrochemical properties. Among the synthesized electrode materials, Ni0.5Co0.5WO4 electrode material delivers the high specific capacity of 634.55 Cg−1 at 1 Ag−1 with an excellent rate capability of 92% after 10,000 cycles at 10 Ag−1. The solid-state supercapattery constructed with Nio.5Co0.5WO4 and reduced graphene oxide as positive and negative electrodes, respectively. The device exhibits the maximum specific capacity of 134.70 Cg−1 at 0.5 Ag−1 and energy density of 56.12 Wh kg−1 at 500 W kg−1 with long-term cyclic stability (90% capacity retentively after 20,000 cycles). The high performance of this electrode material has been attributed to the synergetic effect between bimetallic (Ni and Co) redox centers, a mesoporous structure that provides a larger redox cites, rich electrical conductivity, shorter diffusion length, and faster electrochemical kinetic rates for electrochemical reactions.