Mechanistic Insights of Zn‐Ion Storage in Synergistic Vanadium‐Based Composites

Abstract A novel composite material Na₂V₆O₁₆·3H₂O‐Al_xV₂O₅ (NVO‐AVO) is designed and synthesized for the first time in aqueous zinc ion battery cathode. The electrochemical behavior is elucidated in detail using in situ and ex situ techniques. The NVO‐AVO is simple, inexpensive, and safe to fabricate and contributes to the synergistic effect of orthorhombic Al_xV₂O₅ (AVO) and monoclinic Na₂V₆O₁₆·3H₂O (NVO), the NVO‐AVO composites have fast Zn²⁺ kinetics and exhibit good electrochemical properties. At 300 mA g⁻¹, the specific capacity is as high as 392.5 mA h g⁻¹, and even more excitingly, NVO‐AVO remains a specific capacity of 160.6 mA h g⁻¹ even after 18 300 cycles at 5000 mA g⁻¹, which is significantly better than the stability of both NVO and AVO. The distinctive V₃O₈ layered structure in Na₂V₆O₁₆·3H₂O facilitates the diffusion of Zn²⁺, and structural water located between the V₃O₈ layers facilitates rapid charge transfer by widening the gallery spacing and supposing more storage sites for Zn²⁺. In addition, Al_xV₂O₅ forms [AlO₆] octahedral units that enhance structural stability and play a crucial role in maintaining long‐term cycling stability. This work supports the theoretical basis and technical support for the development and extension studies of new vanadium‐based electrode materials.