Cation-Vacancy Modulated 2D Manganese Oxide Nanobelts for High-Performance Aqueous Zinc-Ion Storage

Abstract

Manganese oxides are promising cathodes for aqueous zinc-ion batteries but still face the challenges of poor conductivity, sluggish ion kinetics, and structural instability, which severely hinder their practical applications. Herein, we propose Mn vacancy-modulated 2D manganese oxide nanobelts (V-MnO2) for high-performance zinc-ion storage. The Mn vacancies not only promote the metallicity of V-MnO2 exhibiting an energy gap of 0.25 eV but also accelerate zinc ion transport with a diffusion coefficient as high as 10–11 cm2 s–1. Based on EXAFS and DFT calculations, the presence of Mn vacancies has led to local lattice distortions and charge redistribution, which could mitigate electrostatic interactions and increase structural stability while providing additional ion host sites. As expected, a high reversible capacity of 261.8 mAh g–1 and a maximum energy density of 343.3 Wh kg–1 can be achieved for V-MnO2, as well as an excellent long-term cycling stability of 71.5% retention after 1500 cycles. This work sheds light on the critical role of cation vacancies in manganese-based cathodes and heralds a simple but effective strategy for advanced aqueous zinc-ion batteries.

Vanadium Oxide Cathode Coinserted by Ni2+ and NH4+ for High-Performance Aqueous Zinc-Ion Batteries

“…To date, the most studied cathode materials include manganese-based compounds, − Prussian blue and its analogs, − as well as some organic compounds. , However, the development of these materials has been hindered by various challenges. For instance, manganese-based compounds suffer from the irreversible phase transition and/or dissolution issue; Prussian blue has a limited capacity and the related organic compounds face the problem of dissolution of discharge products. − In the meantime, vanadium-based materials, such as vanadium oxides and vanadates have recently gained intensive attention due to their high theoretical capacities and low cost .…”