The CuCo2O4/CuO composite-based microspheres serve as a battery-type cathode material for highly capable hybrid supercapacitors

Abstract In this work, CuCo2O4/CuO composite microspheres were easily prepared by an initial solvothermal method with a post annealing treatment of precursor in air. The microstructures and electrochemical performances of the electrode materials annealed at 400, 500, and 600 °C were investigated in details. It was revealed that the composite microspheres obtained at the annealing temperature of 400 °C (CuCo2O4/CuO-400) exhibited the best electrochemical properties including a high specific capacity of 279.36 C g−1 at 1 A g−1 and a good rate performance with 77.21% capacity retention at 10 A g−1. In contrast, the CuCo2O4/CuO composite annealed at 500 and 600 °C delivered specific capacity of 254.94 C g−1 and 224.93 C g−1, respectively. A hybrid supercapacitor (HSC) was assembled with CuCo2O4/CuO composite as cathode and activated carbon (AC) as anode, and the CuCo2O4/CuO-400//AC HSC possessed superior performance such as an energy density of 19.18 W h kg−1 at 770.41 W kg−1 as well as 84.36% capacity preservation over 5000 cycles at 5 A g−1. The present synthetic method is convenient and cost-effective, and can be extended to the preparation of other cobalt-based binary transition metal oxides with excellent electrochemical properties for energy storage and conversion.