Aqueous zinc-ion batteries (ZIBs) have attracted great research interest for use in large-scale energy storage devices due to their inherent safety, environmental friendliness, and low cost. Unfortunately, dendrite growth and interfacial side reactions during the plating/stripping process triggered by uneven electric field distribution on the surface of the Zn anode seriously hinder the further development of aqueous ZIBs. Here, practical and inexpensive sodium tartrate (STA) is used as an electrolyte additive to construct a stable electrode–electrolyte interface, in which STA adsorbs preferentially on the Zn metal surface, contributing to promoting homogeneous Zn deposition. Moreover, STA interacts more strongly with Zn²⁺, which takes the place of the water molecules in the solvated shell and prevents the development of side reactions. In symmetrical cells and full cells, flat Zn anodes can therefore demonstrate remarkable cycle stability, opening the door for the development of cost-effective and effective electrolyte engineering techniques.

Aqueous zinc-ion batteries (ZIBs) are attaining increasing attention for their high safety and low cost. Despite significant progresses in realizing high-performance cathode material for ZIBs, simultaneously endowing them with high capacity and fast-charging capability, the long-term cycling stability remains a major unsolved challenge. In this work, a polyoxovanadate cluster of (NH₄)₈[V₁₉O₄₁(OH)₉]·11H₂O (NOV) is defined as a cathode material for ZIBs that contains mixed-valence vanadium sites (V⁴⁺ and V⁵⁺). A maximum of 26 electrons can be accommodated in one [V₁₉O₄₁(OH)₉]⁸⁻ {V₁₉O₅₀} cluster, contributing to the high theoretical specific capacity of 328 mA·h·g⁻¹. The Ti₃C₂T_x MXene nanosheets are incorporated into NOV with the help of ionic liquid (IL) linkers to restrain the dissolution of vanadium species and facilitate electron transport across the electrode. The interfacial bonding, anion exchange, and electrostatic interactions among NOV and MXene are provided by IL liquid. The nanohybrid of NOV-IL-MXene endows excellent contact between MXene and NOV, thereby enhanced charge transfer is observed at interface. Subsequently, the as-synthesized NOV-IL-MXene cathodes exhibit high discharge capacity of 413 mA·h·g⁻¹ at 0.2 A·g⁻¹ even at high mass loading of 5.2 mg·cm⁻², remarkable rate performance of 182 mA·h·g⁻¹ at 10 A·g⁻¹, and impressive cycling stability of 94% capacity retention after 2000 cycles. This work opens up new opportunities to develop advanced polyoxovanadate hybrid cathodes for low-cost and high-performance aqueous ZIBs.