Investigations on cobalt magnesium vanadate as high performing cathode material for magnesium ion storage

Rechargeable magnesium batteries are promising next-generation energy storage systems due to their safety and resource abundance. However, their development is hindered by sluggish Mg²⁺ ion kinetics. In this study, cobalt magnesium vanadate nanoparticles are synthesized and evaluated as cathode material. Structural, morphological, and elemental characteristics are confirmed through XRD, FESEM, FTIR, Raman, and XPS analyses. The increased interlayer spacing in cobalt magnesium vanadate nanoparticles facilitates Mg²⁺ ion diffusion by shortening migration pathways. Notably, pseudocapacitive contributions at the electrode–electrolyte interface significantly enhance fast ion storage by enabling surface-controlled charge transfer and improving Mg²⁺ kinetics. The redox activity of V⁵⁺/V⁴⁺ and Co³⁺/Co²⁺ facilitates reversible intercalation and deintercalation of Mg²⁺ ions by enabling effective charge compensation during cycling.Cyclic voltammetry reveals distinct insertion/extraction peaks at 2.72 V and 2.33 V vs. Mg/Mg²⁺, corroborated by dQ/dV analysis. An energy density of 214.09 Wh kg⁻¹ is achieved. Ex-situ XPS confirms the redox mechanism and reversible ion transport. This study highlights the synergistic role of pseudocapacitive behavior and structural engineering in enhancing Mg²⁺ storage kinetics, offering a viable pathway for developing high-performance cathodes in rechargeable magnesium batteries.