Boosting the capacitive performance of hierarchical cobalt molybdate hybrid electrodes for asymmetric supercapacitors

Ternary metal oxides have been demonstrated as promising potential materials for various applications such as supercapacitors. Yet, they are still struggling from inferior electrical conductivity, which comes from their natural properties and limited structure used. Herein, a facile hydrothermal route is developed to fabricate reduced graphene oxide (rGO) coating CoMoO₄ on Ni foam substrates. More importantly, the CoMoO₄/rGO electrode shows high electrochemical activity and yields a high areal capacitance of 4.55 F cm⁻² at 4 mA cm⁻² (or specific capacitance of 3033 F g⁻¹), and the capacitance retention remains 92% after 10,000 charge/discharge cycles. The asymmetric supercapacitor is assembled using the prepared CoMoO₄/rGO as the positive electrode and active carbon as the negative electrode, which exhibits a prominent energy density of 82.5 Wh kg⁻¹ and power density of 3.7 kW kg⁻¹. This work demonstrates that the hierarchically structured CoMoO₄/rGO has enormous potential for electrochemical energy storage.