Preparation of cobalt/coal-based activated carbon composites with synergistic electrochemical performance

A facile precipitation approach has been developed to prepare cobalt/coal-based activated carbon composites as an electrode material for supercapacitors. The existence of coal-based activated carbon facilitates the dispersion of Co particles. The electrochemical performance of Co/coal-based activated carbon composites had been characterized by cyclic voltammetry, galvanostatic charge/discharge tests and electrochemical impedance spectroscopy. The specific capacitance of the as-prepared composite material approaches 615 F g^-1 at a current density of 2 A g^-1. And the composite electrode delivers an excellent rate capacity of 495 F g^-1 even at a current density as high as 20 A g^-1. The impressive performance could be ascribed to the synergistic effect of the combination of the pseudocapacitive cobalt nanoparticles and the coal-based activated carbon matrix.