Although Zn metal has been regarded as the most promising anode for aqueous batteries, it persistently suffers from serious side reactions and dendrite growth in mild electrolyte. Spontaneous Zn corrosion and hydrogen evolution damage the shelf life and calendar life of Zn‐based batteries, severely affecting their industrial applications. Herein, a robust and homogeneous ZnS interphase is built in situ on the Zn surface by a vapor–solid strategy to enhance Zn reversibility. The thickness of the ZnS film is controlled via the treatment temperature, and the performance of the protected Zn electrode is optimized. The dense ZnS artificial layer obtained at 350 °C not only suppresses Zn corrosion by forming a physical barrier on the Zn surface, but also inhibits dendrite growth via guiding the Zn plating/stripping underneath the artificial layer. Accordingly, a side reaction‐free and dendrite‐free Zn electrode is developed, the effectiveness of which is also convincing in a MnO2/ZnS@Zn full‐cell with 87.6% capacity retention after 2500 cycles.

Zn metal has been regarded as the most promising anode for aqueous batteries due to its high capacity, low cost, and environmental benignity. Zn anode still suffers, however, from low Coulombic efficiency due to the side reactions and dendrite growth in slightly acidic electrolyte. Here, the Zn plating/stripping mechanism is thoroughly investigated in 1 M ZnSO 4 electrolyte, demonstrating that the poor performance of Zn metal in mild electrolyte should be ascribed to the formation of a porous by-product (Zn 4 SO 4 (OH) 6 •xH 2 O) layer and serious dendrite growth. To suppress the side reactions and dendrite growth, a highly viscoelastic polyvinyl butyral (PVB) film, functioning as an artificial solid/electrolyte interphase (SEI), is homogeneously deposited on the Zn surface via a simple spin-coating This article is protected by copyright. All rights reserved.2 strategy. This dense artificial SEI film not only effectively blocks water from the Zn surface but also guides the uniform stripping/plating of Zn ions underneath the film due to its good adhesion, hydrophilicity, ionic conductivity, and mechanical strength. Consequently, this side-reaction-free and dendrite-free Zn electrode exhibits high cycling stability and enhanced Coulombic efficiency, which also contributes to enhancement of the full-cell performance when it is coupled with MnO 2 and LiFePO 4 cathodes.

Rechargeable aqueous Zn‐ion batteries promise high capacity, low cost, high safety, and sustainability for large‐scale energy storage. The Zn metal anode, however, suffers from the dendrite growth and side reactions that are mainly due to the absence of an appropriate solid electrolyte interphase (SEI) layer. Herein, the in situ formation of a dense, stable, and highly Zn2+‐conductive SEI layer (hopeite) in aqueous Zn chemistry is demonstrated, by introducing Zn(H2PO4)2 salt into the electrolyte. The hopeite SEI (≈140 nm thickness) enables uniform and rapid Zn‐ion transport kinetics for dendrite‐free Zn deposition, and restrains the side reactions via isolating active Zn from the bulk electrolyte. Under practical testing conditions with an ultrathin Zn anode (10 µm), a low negative/positive capacity ratio (≈2.3), and a lean electrolyte (9 µL mAh−1), the Zn/V2O5 full cell retains 94.4% of its original capacity after 500 cycles. This work provides a simple yet practical solution to high‐performance aqueous battery technology via building in situ SEI layers.

Recent research progresses on high performance anode materials for high-energy sodium-ion batteries are comprehensively summarized.