Porous CuCo2O4/CuO microspheres and nanosheets as cathode materials for advanced hybrid supercapacitors

The design of composite electrode material with mesoporous structure is a promising strategy for the assembly of high-performance supercapacitor device, and it may enhance the energy storage capability including the capacity, cycling stability, and energy density (Ed). In this study, porous CuCo2O4/CuO microspheres (MSs) and nanosheets (NSs) were successfully prepared through different methods, respectively. These MSs and NSs exhibit battery-like feature with excellent electrochemical performance and is of great potential for electrochemical energy storage. The CuCo2O4/CuO MSs showed a specific capacity (Cs) of 284.5C g−1 at 1 A g−1 and 217.0C g−1 at 10 A g−1, while those NSs delivered even higher Cs of 337.6C g−1. To assess the potential of practical application, a hybrid supercapacitor (HSC) was assembled with CuCo2O4/CuO composite as cathode and activated carbon (AC) as anode, and this device could run under a high voltage of 0–1.7 V. The CuCo2O4/CuO MSs//AC HSC possessed an Ed of 28.7 W h kg−1 under a power density (Pd) of 0.9 kW kg−1, while the NSs-based HSC delivered a higher Ed of 38.8 W h kg−1 at 1.0 kW kg−1. Moreover, both HSCs exhibited superior cycling performance throughout 3000 cycles at a high current density of 6 A g−1. The present strategy is promising in synthesizing other transition metal oxides (TMOs)-based electrode materials with good electrochemical performance for further assembly of advanced HSC device.