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

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 similar to 350 F g(-1), high working voltage of 1.6 V and an ultrahigh energy density of similar to 120 W h kg(-1).