Self‐Assembled Homogeneous Heterobimetallic‐Oxide Interfaces Enable Synergistic Hydrogen Evolution Passivation for Durable Acidic Zn–Mn Batteries

Acidic Zn-Mn batteries hold promising prospects in large-scale energy storage owing to their higher discharge voltage and capacity. However, the challenge of developing long-term acidic Zn-Mn batteries still remains due to Zn anode instability in acidic media arising from the inevitable proton corrosion and hydrogen evolution reaction (HER). Herein, we report self-assembled homogeneous heterobimetallic-oxide interfaces on the Zn anode surface via a multi-cation (Cu²⁺, In³⁺, and Sn⁴⁺) synergistic regulation strategy to achieve >85.5% depth of discharge with over 1000 h of cycling in strongly acidic medium (pH = 0.9). The design ingeniously blends the SnCl₄ hydrolysis and In³⁺ and Cu²⁺ ions replacement with Zn metal to spontaneously generate heterobimetallic In-CuZn₅ and SnO₂ oxide. Heterobimetallic-oxide interfaces could synergistically inhibit proton corrosion and HER while inducing Zn-ordered plating/stripping benefiting from the excellent acid resistance of SnO₂ and the abundant nucleation sites of heterobimetallic. Crucially, the in situ hydrolysis of SnCl₄ establishes a self-regulated acidic environment without additional acidic medium. Consequently, Zn-Mn pouch battery within this acidic environment delivers a high capacity of 1.39 mAh cm^-2 and retains 84.9% of initial capacity after 200 cycles at 1 mA cm^-2. This direct multi-cation synergistic modulated self-assembly interface strategy holds significant potential for expediting the advancement of high-safety, large-scale energy storage technology.