Gallium Vanadium Oxide-Based Free-Standing Versatile Electrode for Next-Generation Lithium and Sodium Energy Storage: Combined Experimental and First-Principles Insights into Electrochemical Performance

In this study, gallium vanadium oxide mixed-oxide material was synthesized using a simple solid-state reaction followed by an annealing process. Flexible, free-standing gallium vanadium oxide-based composite electrodes were fabricated and evaluated in various energy storage systems, including lithium-ion batteries, sodium-ion batteries, lithium-ion capacitors, and sodium-ion capacitors. Experimental results demonstrated the remarkable versatility of gallium vanadium oxide. The free-standing electrode based on gallium vanadium oxide mixed-oxide materials achieved impressive discharge capacities of 571 mAh g⁻¹ for lithium-ion batteries and 202 mAh g⁻¹ for sodium-ion batteries at a 1 C-rate. These values are close to the theoretical capacities of 588 mAh g⁻¹ for lithium-ion batteries and 236 mAh g⁻¹ for sodium-ion batteries, indicating the high efficiency and performance of the gallium vanadium oxide free-standing electrode. The hybrid-ion capacitors further showcased gallium vanadium oxide's capabilities, with lithium-ion capacitors delivering energy and power densities of 178.24 Wh kg⁻¹ and 16.6 kW kg⁻¹, respectively, and sodium-ion capacitors achieving 130.74 Wh kg⁻¹ and 13.30 kW kg⁻¹. Density functional theory calculations revealed that the incorporation of gallium lowers the formation energy of stable defects in V₂O₅ during ion intercalation and enhances electrical conductivity by reducing the bandgap. The combined experimental and theoretical analysis positions gallium vanadium oxide as a versatile and highly promising material for next-generation sustainable energy storage devices.