Enhanced synergistic redox behaviour of solution-processed mixed metal oxide composite for high-performance hybrid supercapacitors

Recently, mixed metal oxides with doping have received considerable attention due to their enhanced electrochemical performance and rich redox reactions, making them promising candidates for battery-type electrodes in high-performance hybrid supercapacitors. Herein, hierarchical nanoplates-like mixed metal oxides-based Cu_xCo_3-xO₄@Cu₂O composite was successfully synthesized on carbon cloth using a simple wet-chemical method followed by thermal annealing. The in-situ doping of copper ions with cobalt ions driven by hexamethylenetetramine hydrolysis, resulted in vertically aligned mixed metal oxide nanoplate architectures coating on the carbon substrate. Subsequent annealing induced the formation of a biphasic superlattice nanoarchitectured Cu_xCo_3-xO₄@Cu₂O composite on carbon cloth, forming a well-integrated and binder-free redox-type electrode Structural and compositional analysis confirmed the formation of a crystalline, biphasic Cu_xCo_3-xO₄@Cu₂O composite with enhanced redox-active area and high conductivity. Electrochemical measurements revealed superior charge storage performance of the composite electrode, delivering a high specific performance of 982.7 F g⁻¹ (442.2 C g⁻¹) at 3 A g⁻¹, compared to the pristine Co₃O₄ electrode (454.6 F g⁻¹ 204.6 C g⁻¹) with excellent cycling stability (82.7% retention after 5000 cycles) due to synergistic effects of Cu_xCo_3-xO₄@Cu₂O. When assembled into a hybrid supercapacitor with activated carbon, the device delivered maximum energy density of 38.5 Wh kg⁻¹ and power density of 5250 W kg⁻¹ with the high cell voltage of 1.5 V, validating the composite material potential for high-performance energy storage applications.

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