High-performance hybrid supercapacitor based on the porous copper cobaltite/cupric oxide nanosheets as a battery-type positive electrode material

Abstract In this work, CuCo2O4/CuO nanosheets (NSs) and CuCo2O4 oblique prisms (OPs) were synthesized at 130 °C with different amounts of hexamethyltetramine (HMTA) and reaction time through a hydrothermal method, and followed by an annealing treatment of precursors in air. The CuCo2O4/CuO NSs with 40 nm in thickness possessed a large specific surface area of 43.34 m2 g−1 and a mean pore size of 18.14 nm. The electrochemical tests revealed that the CuCo2O4/CuO NSs were belonged to the battery-type electrode material and exhibited a specific capacity of 395.55 C g−1 at the current density of 1 A g−1, higher than 258.16 C g−1 for CuCo2O4 OPs. A hybrid supercapacitor (HSC) was assembled with activated carbon (AC) as negative electrode and CuCo2O4-based materials as positive electrode. The CuCo2O4/CuO NSs//AC HSC exhibited a high energy density of 30.18 Wh kg−1 at a power density of 869.62 W kg−1, and showed a fantastic cycling performance with 105.22% capacity retention over 5000 cycles. In contrast, the CuCo2O4 OPs//AC HSC delivered an energy density 26.27 Wh kg−1 at 916.74 W kg−1. These impressive electrochemical properties indicate that CuCo2O4/CuO NSs may serve as a promising electrode material for the highly capable hybrid supercapacitors in the near future.