Vanadium Oxide with Elevated Interlayers for Durable Aqueous Hybrid Li⁺/Zn²⁺ Batteries

Rechargeable aqueous Zn-ion batteries (ZIBs) are deemed as powerful candidates for large-scale energy-storage systems because of their intrinsic safety, inexpensive cost, and environment friendliness. However, the performance degeneration of ZIBs occurs by virtue of structural instability and uncompetitive conductivity of cathode materials. In this work, a vanadium oxide of Li_0.21Mn_1.44V₈O₂₀·0.55H₂O (4-MLVO) cathode was successfully synthesized for the first time by optimizing the ratio of Mn/V. Intriguingly, the as-assembled traditional aqueous hybrid Li⁺/Zn²⁺ batteries based on the Li_0.21Mn_1.44V₈O₂₀·0.55H₂O cathode, 1 M Li₂SO₄ + 2 M ZnSO₄ electrolyte, and Super P@Zn anode possess superior performance of 350.0 mA h g^–1 at the current density of 0.1 A g^–1 and can accomplish 6000 cycles with 147.5 mA h g^–1 at 10.0 A g^–1. Moreover, the outstanding flexibility of sandwiched quasi-solid-state Zn//4-MLVO batteries with the CMC-Na⁺/PAM hydrogel electrolyte is demonstrated by multifarious deformation tests. The quasi-solid-state batteries at a bending state can achieve a high open voltage of 1.026 V and a specific capacity of 184.8 mA h g^–1 at 0.1 A g^–1. This work offers thoughts for the devisal of aqueous hybrid ZIB cathode materials and lays a foundation for advanced flexible energy devices.