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

Abstract

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.