Asymmetric electrochemical capacitor microdevice designed with vanadium nitride and nickel oxide thin film electrodes

Vanadium nitride thin film has been coupled with electrodeposited nickel oxide in order to design an electrochemical capacitor microdevice. VN has been used as negative electrode while NiO was used as the positive one in 1 M KOH electrolyte. VN exhibits a pseudo-capacitive behavior while NiO shows a faradaic behavior. This asymmetric microdevice has been operated between 0.5 and up to 1.8 V in aqueous based electrolyte (1 M KOH). Long term cycling ability (10,000 charge/discharge cycles) has been demonstrated with interesting energy (1.0 μW h cm^− 2) and power (40 mW cm^− 2) densities.