Synthesis and properties of a ternary transition metal compound as positive electrode for high-performance supercapacitors

A nanostructured NixFeyCuz(CO3)(OH)2 electrode with a large surface area was deposited on a Ni-foam substrate using a facile hydrothermal method. The well-organized microscopic and free-standing nano-sized ternary metal compounds exhibited high electrical conductivity and competent ion transport ability. This composite is particularly attractive for high-performance power-storage systems owing to its binder-free nature and exceptional value as a current-carrying electrode. Ternary electrodes containing three transition metals have a higher entropy than binary electrodes, which reduces the movement distance of ions on the electrode surface and enhances key electrochemical advantages, thereby providing a high specific capacitance with durability and cycling stability when coated with a highly conductive electrochemical pattern. The NixFeyCuz(CO3)(OH)2 compound demonstrated remarkable specific surface area of 106 m2 g-1 and high specific capacities of 271.8 and 75.2 mAh g-1 at current densities of 3 and 15 A g-1. In addition, an asymmetric supercapacitor fabricated with the NixFeyCuz(CO3)(OH)2 compound as the positive electrode and graphene as the negative electrode exhibited a high energy density of 55.1 W h kg-1 at power and current densities of 398.5 W kg-1 and 2 A g-1, respectively, as well as a remarkable cycling stability of 84.3 %, which was maintained following 10,000 long cycles.