Nickel Nanoparticles Anchored onto Ni Foam for Supercapacitors with High Specific Capacitance

Supercapacitors are regarded as a promising energy storage system. Transition metal compounds have been widely used as electrode materials for pseudocapacitors, which possess variable oxidation valence states. Among them, Ni-based materials have drawn a substantial amount of attention. In this work, Ni nanoparticles (NiNPs/NiF) were successfully synthesized on Ni foam by a facile ion implantation method and first studied for the supercapacitor application. At the same time, NiO nanofibers were grown on a Ni foam (NiOF/NiF) for comparison. The NiNPs/NiF electrode delivered a better performance than the NiOF/NiF. The NiNPs/NiF electrode showed a high specific capacitance of 3862 F g^-1 at 5 A g^-1 and good long-term endurance at a current density of 50 A g^-1 after a charge-discharge test of 1000 cycles. The good performance can be attributed to the uniform deposition of the Ni nanoparticles, which provided abundant active sites for the Faradaic reaction. Moreover, the three-dimensional (3D) structure of Ni foam facilitated the electron transfer between the electrode and electrolyte. The excellent performance and facile fabrication make the NiNPs/NiF electrode a promising candidate for high-performance supercapacitors.