Synergistic Electro-Chemo-Structural Interface Engineering for Stable Aqueous Zn-MnO2 Batteries

Manganese oxide (MnO2) has been considered an ideal cathode material for aqueous zinc-ion batteries (AZIBs) owing to its high theoretical capacity and natural abundance. Nevertheless, its practical application is restricted by sluggish electrochemical reaction kinetics and rapid capacity fading caused by Mn dissolution and the accumulation of byproducts. Here, we present a chemo-electrostructural interface modification strategy. Through electrochemical pretreatment, a uniform structural physical buffer interface comprising zinc phosphate and ammonium, named as PN-MnO2, is built as a pH-buffering layer to inhibit Mn dissolution chemically as well as an ionic pump to facilitate the ion diffusion from an electrochemical perspective. As a result, the cells with PN-MnO2 cathode exhibit 175 mAh g–1 over 1,500 cycles at 1 A g–1, while pouch cells deliver a stable capacity of 12 mAh cm–2 over 80 cycles at 5 mA cm–2. Moreover, practical viability is demonstrated by powering smartphones and light strips, highlighting AZIB’s scalable potential.