Achieving high-performance manganese oxide-based aqueous zinc-ion batteries via a heterostructure strategy

Manganese dioxide (MnO₂) is recognized as one of the most promising cathode materials for aqueous zinc-ion batteries (AZIBs), primarily owing to its high theoretical specific capacity, low cost, and superior safety. However, issues such as manganese dissolution during charge-discharge cycling, poor electrical conductivity, and sluggish ion diffusion kinetics significantly hinder its commercial application. Here, we propose a novel α/β-MnO₂ heterostructure as a positive electrode material for zinc-ion batteries. This structural design aims to synergistically combine the fast ion diffusion channel of α-MnO₂ with stable framework of β-MnO₂. Combining theoretical calculations and experiment results indicate that the lattice expansion caused by heterostructure provides a larger channel for ion diffusion, facilitating Zn²⁺ rapid migration. Meanwhile, the formative built-in electric field and β-phase anchoring effect jointly promote reversible phase transformation, mitigating Jahn-Teller distortion and Mn dissolution. Therefore, the α/β-MnO₂ heterostructure demonstrated a maximum specific capacity of 402.7 mA h g^-1 at 0.1 A g^-1. Moreover, this cathode exhibited an exceptional cycle life of 1000 cycles at 1 A g^-1, maintaining a high capacity retention rate of 77%. This work offers new insights into the rational design of high-capacity and long-cycle MnO₂-based cathode materials for aqueous zinc-ion batteries.