Monoclinic Co-doped BiVO4 nanosphere for high performance supercapacitor

Abstract

As fossil fuel resources decline, the world relies more on efficient, sustainable energy storage devices, where supercapacitors stand out among electrochemical energy storage devices. Supercapacitors are characterised by their ability to charge and discharge at ultrafast rates, making them highly suitable for applications that demand quick energy delivery. A facile one step hydrothermal method was employed to synthesis Co-BiVO₄ nanoparticles. The designed Co-BiVO₄ demonstrated enhanced specific capacitance, attributed to the enhanced conductivity and optimized nanostructures. The observed decrease in R_ct value from 3.3 Ω in pristine BiVO₄ to 2.2 Ω upon Co-BiVO₄ demonstrates improved electrical conductivity and faster charge transfer. This enhancement is directly associated with the increased specific capacitance of the Co-doped BiVO₄ electrode. The electrode achieved a high specific capacitance of 424.8 Fg⁻¹ at a current density of 1 Ag⁻¹, retaining 88.75 % capacitance after 5,000 cycles at 10 Ag⁻¹ in a three-electrode system. Asymmetric supercapacitors were fabricated using carbon as the negative electrode and Co-BiVO₄ as the positive electrode. The ASC delivered an Energy density of 56.67 Whkg⁻¹ at a power density of 807 Wkg⁻¹ with a retention rate of roughly 81.15 % after 10,000 cycles at 10 Ag⁻¹.