Bimetallic Ion Intercalation Optimized the Performance of Hydrated Vanadate Cathodes for Aqueous Zinc Ion Batteries

Aqueous zinc ion batteries are gaining prominent attention due to their potentially high safety, low cost, and high volumetric capacity. However, disparities still exist in specific capacity and kinetic performances within the electrode materials of zinc ion batteries. Herein, the electrochemical and kinetic properties of layered vanadium oxide (VOH) nanorods adopting Sr2+ and La3+ as pillars were investigated systematically. It was shown that (1La,1Sr)-VOH possessed a specific capacity around 345.8 mAh g-1 at a current density of 1 A g-1, which was remarkably higher than that of VOH and 1Sr-VOH (208.34 mAh g-1). Characterizations demonstrated that benefiting from the role of Sr2+ and La3+ as pillars, (1La,1Sr)-VOH possessed enlarged layer spacing and enhanced zinc ion storage kinetics during electrochemical reactions. The tested zinc ion diffusion coefficient was 1.16 x 10-11 cm2 s-1, which was much higher than that of VOH (7.31 x 10-12 cm2 s-1), demonstrating a smooth charge transfer process in the as-synthesized (1La,1Sr)-VOH.