Asymmetric micro-supercapacitors based on electrodeposited Ruo2 and sputtered VN films

Research on micro-supercapacitors remains one of the most important activities in the area of electrochemical energy storage for powering smart and miniaturized electronic devices. Here we design an asymmetric microsupercapacitor (A-MSC) combining sputtered vanadium nitride film (VN) and electrodeposited hydrous ruthenium oxide (hRuO(2)) film. Taking advantage of their complementary electrochemical potential windows in 1 M KOH electrolyte, the A-MSC achieves a cell voltage up to 1.15 V, associated to high specific capacitance values for the device (approximate to 100 mF cm(-2)). The energy density of this asymmetric VN/hRuO(2) micro-supercapacitor reaches 20 mu Wh cm(-2) at a power density of 3 mW cm(-2). Taking benefit from the asymmetric configuration, a 5-fold enhancement factor in energy density is demonstrated for the VN/hRuO(2) asymmetric micro-supercapacitor as compared to symmetric VN/VN and hRuO(2)/hRuO(2) microdevices.