Preparation of a hybrid Cu2O/CuMoO4 nanosheet electrode for high-performance asymmetric supercapacitors

Abstract

Supercapacitors have attracted considerable attention due to their fast charge–discharge ability, excellent rate capability and long-term stability. In this study, a novel electrode composed of Cu₂O/CuMoO₄ nanosheets directly grown on Ni foam was synthesized via a facile hydrothermal method. The as-prepared electrode exhibits remarkably improved specific and areal capacitance (up to 4264 F g⁻¹ and 9.38 F cm⁻² at a current density of 1 A g⁻¹). To the best of our knowledge, the specific capacitance of 4264 F g⁻¹ is the highest in reported studies although the areal capacitance of 9.38 F g⁻¹ is slightly lower than the highest value of 16 F cm⁻² when Ni(OH)₂/carbon nanotubes on Ni foam was used as the electrode. An asymmetric supercapacitor is fabricated using the Cu₂O/CuMoO₄ nanosheet electrode as the positive electrode and activated carbon (AC) as the negative electrode. The operation voltage could expand to 1.7 V, at which the energy density can reach 75.1 W h kg⁻¹ with a power density of 420 W kg⁻¹. Additionally, the asymmetric supercapacitor exhibits very high rate capability and good cycling stability. The capacitance remains around 86.6% after 3000 cycles at a current density of 5 A g⁻¹. This indicates that the Cu₂O/CuMoO₄ nanosheet electrode is promising for applications in renewable energy storage in the future.