Studies on fabrication of high-performance flexible printed supercapacitor using cobalt hydroxide nanowires

Abstract

We report the successful fabrication and testing of a printed symmetric flexible supercapacitor based on cobalt hydroxide nanowire-carbon ink composite. The urea hydrolysis method provides a controlled way of cobalt hydroxide nanowire formation. The microscopic studies reveal nanowires with an average diameter of approximately 70 nm. Moreover, the material exhibited a high specific surface area of 13.08 m2g−1 and a pore volume of 0.060 cc g−1. Electrochemical studies with the nanocomposite revealed a very high areal capacitance. The cobalt hydroxide nanowire was used for fabricating a printed supercapacitor prototype using PVA/KOH gel as the electrolyte. It exhibited a high areal capacitance of 6.27 mF cm−2 with 0.7101 μWh cm−2 areal energy density and 32.7 μW cm−2 areal power density. Excellent capacitance retention was observed even after 8500 charge-discharge cycles. Series combination of printed capacitors yields summation of individual potentials, and its application was demonstrated using different LEDs and electronic devices. Furthermore, excellent capacitance retention at various bending angles and the performance remains the same even after 1500 bending cycles show high mechanical stability. Hence, it finds potential applications in flexible and wearable electronics.