Boosting the electrochemical performance of ZnO nanomaterials through a conductive CuS matrix for aqueous supercapacitors

Abstract

The impressive electrochemical performance of metal oxides/metal sulfides and their derivatives can assist the development of innovative electrodes for achieving a remarkable performance for supercapacitors. Herein, we report ZnO/CuS as a novel binary composite with different ratios of CuS (10% and 40% with nomenclature of G-1 and G-2) to probe their electrochemical performance to achieve optimum performance in these hierarchical nanostructures. The synergistic effect of CuS as a nanostructure collector has supported ZnO nanorods, as both are pseudocapacitive materials. Morphological and structural analysis reveals nanorods and nanoparticles like ZnO and CuS were obtained with high purity and crystallinity without any by-product formation during the synthesis process. The electrochemical investigations indicate that all electrodes show typical capacitive behavior in the high potential of −0.1 to 0.7 V in a three-electrode setup with good reversibility and charge storage properties (capacitance: 487 F g⁻¹, low resistance: 2.17 Ω) following a rapid pseudocapacitive charge storage mechanism. Remarkable stability is achieved (91.2%) with good rate performance when an optimized voltage of 1.8 V is added as assembled G-2//AC ASC in a 3 M KOH solution. More strikingly, extremely high power is attained at 13 448 W kg⁻¹ at a maximum energy density of 26 W h kg⁻¹. These results manifest the importance of other transition metal oxide-based electrodes to achieve significantly improved performance.