Printed Electrodes Based on Vanadium Dioxide and Gold Nanoparticles for Asymmetric Supercapacitors.

Printed energy storage components attracted attention for being incorporated into bendable electronics. In this research, a homogeneous and stable ink based on vanadium dioxide (VO 2 ) is hydrothermally synthesized with a non-toxic solvent. The structural and morphological properties of the synthesized material are determined to be well-crystalline monoclinic-phase nanoparticles. The charge storage mechanisms and evaluations are specified for VO 2 electrodes, gold (Au) electrodes, and VO 2 /Au electrodes using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The VO 2 electrode shows an electrical double layer and a redox reaction in the positive and negative voltage ranges with a slightly higher areal capacitance of 9 mF cm -2 . The VO 2 /Au electrode exhibits an areal capacitance of 16 mF cm -2 , which is double that of the VO 2 electrode. Due to the excellent electrical conductivity of gold, the areal capacitance 18 mF cm -2 of the Au electrode is the highest among them. Based on that, Au positive electrodes and VO 2 negative electrodes are used to build an asymmetric supercapacitor. The device delivers an areal energy density of 0.45 μWh cm -2 at an areal power density of 70 μW cm -2 at 1.4 V in the aqueous electrolyte of potassium hydroxide. We provide a promising electrode candidate for cost-effective, lightweight, environmentally friendly printed supercapacitors.