Selenization of NiCo₂S₄ Spinel Structure to Reduce the Charge Transfer Resistance for Supercapacitor Electrode

Abstract

Due to the semiconductor properties and the weak charge transfer ability, the further application of spinellide material will be hindered in energy storage. Herein, the NiCo2S4 prepared by the two‐step method is modified adopting Se powder with different mass ratios under aqueous solvothermal conditions. Thanks to the selenide formed on the surface, the Se‐NiCo2S4‐10 sample exhibits a specific capacitance of 713 F g−1 at the current density of 1.0 A g−1, which is 2.6 times higher than that of pure NiCo2S4. Commercially, the assembled asymmetric supercapacitors Se‐NiCo2S4‐10//AC present an energy density of 25.13 Wh kg−1 under the power density of 753.9 W kg−1. This work shows that surface selenization has the effect of reducing charge transfer on spinel‐like nanomaterials, which provides a modified idea for the application of spinel materials in supercapacitor electrodes.