An efficient electrode material for high performance solid-state hybrid supercapacitors based on a Cu/CuO/porous...

A Cu/CuO/porous carbon nanofiber/TiO₂ (Cu/CuO/PCNF/TiO₂) composite uniformly covered with TiO₂ nanoparticles was synthesized by electrospinning and a simple hydrothermal technique. The synthesized composite exhibits a unique morphology and excellent supercapacitive performance, including both electric double layer and pseudo-capacitance behavior. Electrochemical measurements were performed by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The highest specific capacitance value of 530 F g^-1 at a current density of 1.5 A g^-1 was obtained for the Cu/CuO/PCNF/TiO₂ composite electrode in a three-electrode configuration. The solid-state hybrid supercapacitor (SSHSC) fabricated based on this composite exhibits a high specific capacitance value of 330 F g^-1 at a current density of 1 A g^-1 with 78.8% capacitance retention for up to 10,000 cycles. At the same time, a high energy density of 45.83 Wh kg^-1 at a power density of 1.27 kW kg^-1 was also realized. The developed electrode material provides new insight into ways to enhance the electrochemical properties of solid-state supercapacitors, based on the synergistic effect of porous carbon nanofibers, metal and metal oxide nanoparticles, which together open up new opportunities for energy storage and conversion applications.