LAUSR

Rechargeable aqueous batteries with Zn2+ as a working‐ion are promising candidates for grid‐scale energy storage because of their intrinsic safety, low‐cost, and high energy‐intensity. However, suitable cathode materials with excellent Zn2+‐storage cyclability must be found in order for Zinc‐ion batteries (ZIBs) to find practical applications. Herein, NaCa0.6V6O16·3H2O (NaCaVO) barnesite nanobelts are reported as an ultra‐stable ZIB cathode material. The original capacity reaches 347 mAh g−1 at 0.1 A g−1, and the capacity retention rate is 94% after 2000 cycles at 2 A g−1 and 83% after 10 000 cycles at 5 A g−1, respectively. Through a combined theoretical and experimental approach, it is discovered that the unique V3O8 layered structure in NaCaVO is energetically favorable for Zn2+ diffusion and the structural water situated between V3O8 layers promotes a fast charge‐transfer and bulk migration of Zn2+ by enlarging gallery spacing and providing more Zn‐ion storage sites. It is also found that Na+ and Ca2+ alternately suited in V3O8 layers are the essential stabilizers for the layered structure, which play a crucial role in retaining long‐term cycling stability.