Local structure and ion storage properties of vanadate cathode materials regulated by the pre-alkalization

Abstract

Aqueous Zn-ion batteries using mild acidic electrolytes utilizing a Zn²⁺/H⁺ dual-ion storage mechanism have shown great potential in achieving high energy density comparable to non-aqueous lithium-ion batteries. This study reveals that hydrated alkali-ions regulate the formation of alkali-intercalated vanadate layered compounds. Among various vanadate materials, lithium-intercalated vanadate has the largest interlayer spacing and most disordered local structure, exhibiting the largest storage capacity of 308 mA h g⁻¹ at 0.05 A g⁻¹ for Zn²⁺/H⁺ dual-ion storage and improved charge transfer and transport kinetics and cycling performance, evidenced by in situ X-ray diffraction and ex situ X-ray total scattering and pair distribution function analysis. Our study provides new insight into designing layered vanadate materials for high-capacity aqueous batteries.