Synergistic enhancement of electrochemical performance in Co3O4/CuO/rGO heterostructures composite for high-energy, high-rate supercapattery devices

Supercapatteries in electronics and automobiles often suffer from low energy density and specific capacities. A novel sponge-like CuO/Co3O4/rGO heterostructures was synthesized using a hydrothermal method and used as an anode in high-performance supercapatteries with an alkaline electrolyte. This material's high surface area enhances electrode-electrolyte contact, promoting rapid reaction kinetics and improved conductivity. The Co3O4/CuO/rGO electrodes showed increased surface area, rate capability, and reaction kinetics due to ample electroactive sites, multiple ion transport pathways, and superior charge collection, aided by graphene oxide (GO). Optimized annealing of Co3O4/CuO further improved redox capability and stability. The Co3O4/CuO/rGO heterostructures achieved an ultra-high specific capacitance of 642 C g-1 at 1 A g-1, excellent rate capability, and 91% capacitance retention after 10,000 cycles at 10 A g-1. In a supercapattery device with Co3O4/CuO/rGO as the anode and activated carbon (AC) as the cathode, it delivered a high specific capacity of 337 C g-1 at 1 A g-1, a power density of 808 W kg- 1, and an energy density of 75 Wh kg-1. The solid-state device maintained excellent rate capability (99%) after 10,000 cycles in PVA-KOH gel electrolytes, with the hierarchical nanostructure providing abundant active sites and shortened ion transport pathways.