Reversible (De)Intercalation of Hydrated Zn 2+ in Mg 2+ ‐Stabilized V 2 O 5 Nanobelts with High Areal Capacity

The rechargeable aqueous zinc ion battery (ZIB) is regarded as one of the most promising candidates for large-scale energy storage applications due to its low-cost and eco-friendly properties. However, the development of a suitable cathode operating with high areal capacity and uncovering the relevant reaction mechanisms remain challenging. Herein, the application of Mg0.26V2O5·0.73H2O (MVO) nanobelts as a ZIB cathode is demonstrated. In situ FT-IR reveals the shift of OH stretching from 3350 cm−1 to 3200 cm−1, corresponding to the hydration shell of Zn2+, while in situ Raman suggests the interlayer charges creening effect, which would boost the intercalation of hydrated Zn2+. Density function theory reveals that the hydrated Zn2+ can lower the Coulombic repulsion at the electrode-electrolyte interface and circumvents the desolvation penalty of hydrated Zn2+ during the (de)intercalation process. Additionally, excellent structure stability and large interlayer spacing guarantee the highly reversible (de)intercalation of hydrated Zn2+. Therefore, the MVO nanobelts exhibit a high areal capacity of 2.12 mAh cm−2 at 0.05 A g−1, outstanding cycling stability of 2500 cycles at 10 A g−1 with a mass loading of 5 mg cm−2. It is believed that the use of hydrated intercalation charge carriers will boost further studies in other multivalent rechargeable batteries.