High-Performance ZnCo₂O₄/MnMoO₄ Nanosheet Array Electrodes for Asymmetric Supercapacitors

Metal molybdate compounds are highly promising supercapacitor electrode materials due to their excellent specific capacitance and mechanical stability. In this study, a ZnCo2O4/MnMoO4 composite electrode featuring a porous, interconnected nanosheet array structure was synthesized using a two-step hydrothermal method. The nanocomposite showed a remarkable specific capacitance of 1988 F g–1 at 1 A g–1 and retained 95% capacitance after 5000 cycles. The highly permeable nanosheet structure, combined with the synergistic interaction between ZnCo2O4 and MnMoO4, contributed to its high specific capacitance. An asymmetric supercapacitor (ASC) comprising the ZnCo2O4/MnMoO4 electrode and activated carbon operating at a maximum voltage of 1.7 V delivered a notable energy density of 51 Wh kg–1 at a power density of 842 W kg–1. After 5000 cycles, the ASC retained 99% of its capacitance. The interconnected porous nanosheets enhanced the number of electroactive sites and facilitated the efficient electron flow. Two ASC devices connected in series continuously powered a light-emitting diode (LED) for over 15 min, demonstrating the practical applicability of the ZnCo2O4/MnMoO4 electrode in high-performance supercapacitor applications requiring long lifespans.