Size Effects in Ni/Ni(OH)₂ Nanomaterials for Electrochemical Capacitors

Abstract

Electrochemical capacitors based on redox-active metal oxides show great promise for many energy-storage applications. These materials store charge through both electric double-layer charging and faradaic reactions in the oxide. The dimensions of the oxide nanomaterials have a strong influence on the performance of such capacitors. Not just due to surface area effects, which influence the double-layer capacitance, but also through bulk electrical and ionic conductivities. Ni(OH)2 is a prime candidate for such applications, due to low cost and high theoretical capacity. We have examined the relationship between diameter and capacity for Ni/Ni(OH)2 nanorods. Specific capacitances of up to 511 F/g of Ni were recorded in 47 nm diameter Ni(OH)2 nanorods.