Recent Advances in Aqueous Zn||MnO2 Batteries

Recently, rechargeable aqueous zinc-based batteries using manganese oxide as the cathode (e.g., MnO2) have gained attention due to their inherent safety, environmental friendliness, and low cost. Despite their potential, achieving high energy density in Zn||MnO2 batteries remains challenging, highlighting the need to understand the electrochemical reaction mechanisms underlying these batteries more deeply and optimize battery components, including electrodes and electrolytes. This review comprehensively summarizes the latest advancements for understanding the electrochemistry reaction mechanisms and designing electrodes and electrolytes for Zn||MnO2 batteries in mildly and strongly acidic environments. Furthermore, we highlight the key challenges hindering the extensive application of Zn||MnO2 batteries, including high-voltage requirements and areal capacity, and propose innovative solutions to overcome these challenges. We suggest that MnO2/Mn2+ conversion in neutral electrolytes is a crucial aspect that needs to be addressed to achieve high-performance Zn||MnO2 batteries. These approaches could lead to breakthroughs in the future development of Zn||MnO2 batteries, offering a more sustainable, cost-effective, and high-performance alternative to traditional batteries.