Asymmetric metal oxide pseudocapacitors advanced by three-dimensional nanoporous metal electrodes

Abstract

We report a novel RuO₂–NPG//Co(OH)₂–NPG asymmetric supercapacitor with a high specific capacitance and a wide potential window in which bifunctional nanoporous gold is used as both the highly conductive supports of the pseudocapacitive oxides and the 3D current collectors in the device. The RuO₂–NPG and Co(OH)₂–NPG electrodes can reach specific capacitances of 1300 F g⁻¹ and 1800 F g⁻¹, respectively, which provide comparatively high specific capacitances in relation to metal oxide/carbon electrodes, giving rise to an asymmetric oxide pseudocapacitor with a large capacitance of ∼350 F g⁻¹, high working voltage of 1.6 V and an ultrahigh energy density of ∼120 W h kg⁻¹.