MBene promoted Zn peroxide chemistry in rechargeable near-neutral Zn–air batteries†
Abstract
Highly reversible Zn–air batteries (ZABs) in near-neutral aqueous electrolytes can suppress the formation of Zn dendrites and carbonates. However, near-neutral ZABs (NNZABs) based on Zn peroxide (ZnO2) chemistry are challenging to build due to the air circulation requirement and the Swagelok structure. To achieve cost-effective NNZABs in a coin-cell configuration, it is essential to explore air-breathing cathodes with high catalytic activity for near-neutral systems. Previous studies focused on catalysts for alkaline ZABs, which are usually not suitable for near-neutral batteries. Here, Mo4/3B2−xTz MBene with ordered vacancies is for the first time exploited as a high-performance catalyst for NNZABs. Interestingly, a stable lifecycle for 380 h under a current density of 2 mA cm−2 and a 5 h cycling period was achieved, which is attributed to the high O2-adsorbability and air stock capacity of Mo4/3B2−xTz MBene. We also demonstrate that the vacancies at the Y sites of Mo4/3B2−xTz MBene are active sites for boosting the sluggish kinetics of ZnO2 chemistry. This work highlights the significance of introducing highly efficient cathode catalysts for NNZABs and the high efficiency of MBenes as catalysts in near-neutral systems.