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 (VO₂) 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 VO₂ electrodes, gold (Au) electrodes, and VO₂/Au electrodes using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The VO₂ 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 VO₂/Au electrode exhibits an areal capacitance of 16 mF cm^-2, which is double that of the VO₂ 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 VO₂ 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.