Constructing a Fluoride‐Ion Tunnel‐Structured Interface to Stabilize the Zn Metal Chemistry at 50 °C

Abstract High‐temperature aqueous zinc batteries have recently garnered significant attention for large‐scale energy storage. However, spontaneous hydrogen evolution and passivation on the Zn metal anode severely affect its cycling stability under elevated temperature conditions. Herein, a facile strategy is employed to construct a bifunctional composite protective layer comprising an insulating ZnF₂ layer combined with Zn affinity conductive tin (Sn) metal. This combination optimally distributes Zn ions (Zn²⁺) and maintains consistent thermal field distribution around Zn anodes. Moreover, the presence of fluorides on the interface efficiently suppresses the hydrogen evolution reaction, while the Sn metal serves as nucleation seeds with reversible alloying and dealloying process to endow dendrite‐free morphology and fast reaction kinetics. Specifically, the symmetric cell with the coated electrode exhibits excellent stability at a current density of 3 mA cm⁻² over 420 h at 50 °C. When coupled with the modified Zn anode and I₂ cathode, the Zn//I₂ full cells deliver high areal capacity and substantiate their practical application, exhibiting remarkable high‐temperature resilience over 2000 cycles with 97.8% capacity retained at 50 °C.