Tailoring electrochemical and dielectric properties of SrO nanostructures through Cr-doping for energy storage applications

Supercapacitors emerge as a revolutionary technology with the potential to transform future energy storage. Alkaline-earth metals are proposed as a promising option for high-performance supercapacitors due to their excellent redox characteristics and high energy density. However, their poor conductivity restricts applications. A propitious strategy involves incorporating transition metals to amplify alkaline-earth metal-based supercapacitor performance. In this study, we synthesize Cr-doped SrO nanostructures using the hydrothermal method. Structural analyses via X-ray diffraction and scanning electron microscopy unveil the cubic arrangement and rod-like morphology, respectively. Energy-dispersive X-ray spectroscopy corroborates the presence of essential elements: Sr, Cr, and O. Remarkably, UV-Vis measurements demonstrate a progressive reduction in energy bandgap (from 6.24 eV to 5.67 eV) with increasing Cr content. Photoluminescence spectra accentuate excitation at 300 nm, encompassing a broad emission band spanning 350 to 540 nm. With the infusion of Cr through doping, both ac (σac) conductivity and dielectric constant exhibit marked augmentation, concomitantly reducing dielectric loss. Impressively, the optimized 10% Cr-doped SrO electrode manifests a maximum specific capacitance (C_sp) of 806 F/g at 1 A/g, accompanied by a specific energy of 28 Wh/kg and a remarkable specific power of 250 W/kg. Even after 3000 cycles, the optimized electrode exhibits an outstanding retention rate of 84%. Consequently, synthesized electrode materials emerge as a preeminent choice for advanced energy storage devices.