Green anisotropic carbon-stabilized polylaminate copper oxide as a novel cathode for high-performance hybrid supercapacitors

Metallic oxides are promising electrochemically active materials which can supply large energy density and capacitance, while always suffer from weak electrical conductivity and structural stability. Herein, a green and low-tortuosity wood-derived anisotropic carbon is developed to stabilize CuO and improve its conductivity. The low tortuosity and large surface area of anisotropic carbon is capable to act as an electrolyte storage to supply fast transport channels for the ionic migration, which is verified by the kinetic analysis. As expected, the composite electrode has superior electrochemical performances with a large specific capacitance of 694.8 F g−1 at the current density of 0.5 A g−1 (131.5% and 344.2% higher than that of the individual CuO (300.1 F g−1) and the individual carbon (156.4 F g−1)) and high cycling stability. As the current density dramatically increases 100 times to 50 A g−1, the composite electrode still retains 46.7% of the original capacitance, reflecting its outstanding rate capability. More importantly, the composite acts as an advanced cathode material to assemble hybrid supercapacitors, possessing a high cell voltage of 1.5 V and good cycling stability (91.2% capacitance retention after 5000 cycles) and high energy density (13.6 W h kg−1 at 350.3 W kg−1).