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

Abstract

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.