Facet/Interphase Dual Engineering of Zn Anodes via Silicotungstic Acid Etching for Highly Reversible Aqueous Zinc‐Ion Batteries

ABSTRACT

Rechargeable aqueous zinc ion batteries (AZIBs) are constrained by dendrite growth and water driven side reactions at the zinc anode, which erode reversibility and shorten cycle life. Here we show that a single silicotungstic acid (STA) etching step can simultaneously engineer the crystal orientation and interfacial chemistry of zinc anodes. The etching selectively reconstructs the Zn surface to expose Zn(101) facets while introducing a Keggin‐type [SiW ₁₂ O ₄₀ ] ⁴⁻ ‐rich interphase. This dual engineered architecture accelerates interfacial charge transfer, raises the Zn ²⁺ transference number from 0.38 to 0.62, and lowers the desolvation activation energy from 38.70 to 28.51 kJ mol ⁻¹ , while the interphase suppresses hydrogen evolution and corrosion. As a result, the STA‐Zn anode sustains uniform, dendrite free deposition with the favorable (101) texture retained during cycling. In symmetric cells, STA‐Zn delivers a stable lifespan exceeding 3100 h, and the Zn||Ti cell maintains an average Coulombic efficiency (CE) of 97.95% ± 2.95% after 2000 cycles. A Zn||α‐VO ₂ full cell further demonstrates increased rate capability, cycling stability, and anti‐self‐discharge performance. This work shows that one step etching can couple facet engineering with interphase design, providing a practical route toward highly reversible zinc metal anodes.