Enhanced pseudocapacitance of amorphous oxy-hydroxides epitaxially grown on intermetallics nanofoam

Abstract Transition metal oxide based pseudocapacitors possess the merits of high theoretical specific capacitance and high energy density. However, the poor rate performance especially for thick electrodes, originating from the poor conductivity of most transition metal oxides, is still a hindrance for their practical applications. To resolve the conundrum, increasing the conductivity of metal oxides and developing new electrode constructions with high electron/ion conductivity are effective alternatives to acquire high-rate performance and high specific capacitance. In this study, we report a facile approach to fabricate low-cost transition metal based amorphous oxy-hydroxide epitaxially grown on intermetallics nanofoam by electrochemical polarization in an alkaline solution. The enhanced electron/ion conductivity, generated from the continuous metal substance and pore channel networks in the whole electrode, as well as amorphous structure induced transportation channels of oxy-hydroxide, contributes to the ultrahigh specific capacitance (1058 F/cm 3 at a current density of 1 A/cm 3 ) and excellent rate performance (74.2% retention when the current density increases from 1 A/cm 3 to 10 A/cm 3 ). Combined with their excellent cyclic stability and low cost, the 3D amorphous oxy-hydroxide/metal architectures demonstrate great potentials for applications in next generation supercapacitors.