Dynamic Protective Multi-Layers for MnO₂ Cathodes: Ion Sorting and Structural Protection for Superior Zinc-Ion Battery Cycling Performance.

Abstract

Aqueous zinc metal batteries (AZMBs) are characterized by high safety, low cost, and eco-friendliness, among which manganese-based cathodes stand out due to their abundance and high theoretical capacity. However, failure behaviors such as lattice collapse, Mn dissolution, and sluggish kinetics hinder their application. Herein, a dynamic multi-protective interface has been designed through a simple one-step manufacturing process, emulating the structural and functional attributes of biological membranes and cell walls. It comprises three distinct layers: an outer high-valent oxide layer that enhances chemical stability and selectively facilitates proton intercalation while governing the intercalation of Zn²⁺; a middle low-valent oxide and metal composite layer, which functions as a buffer to selectively adsorb Mn²⁺, thereby inhibiting Mn dissolution and augmenting the chemical stability of the cathode; and an inner heterojunction layer, which boosts conductivity and alleviates Jahn-Teller distortion through lattice distortion and entropy-mediated electronic delocalization. The surface modified cathode exhibits outstanding stability, with nearly zero capacity decay observed over 300 cycles at a low current density of 0.4 A g^-1, and 15 000 cycles under a high current of 10 A g^-1. With significantly enhanced cycling stability, rate capability, and electrochemical reversibility, this strategy presents a promising solution for high-performance MnO₂-based cathodes in AZMBs.