Phase-Transformation-Activated MnCO₃ as Cathode Material of Aqueous Zinc-Ion Batteries

The intrinsic high safety of rechargeable aqueous batteries makes them particularly advantageous in the field of large-scale energy storage. Among them, rechargeable Zn–Mn batteries with high energy density, low cost, high discharge voltage, and nontoxicity have been considered as one of the most promising aqueous battery systems. However, exiting research on manganese-based cathode materials mainly focuses on diverse manganese oxides analogs, while reports on other promising manganese-based analogs with high performance are still limited. Herein, we report a MnCO₃ cathode material, which can be manufactured on a large scale by a facile coprecipitation method. Interestingly, the MnCO₃ can spontaneously be converted into MnO₂ material during the charging process. The Zn–MnCO₃ battery delivers a highly specific capacity (280 mAh g⁻¹) even at the high current density of 50 mA g⁻¹. It is also noteworthy that the battery with a high loading mass (7.2 mg cm⁻²) exhibits good reversibility of charge–discharge for 2000 cycles, showing a competitive cycling stability in aqueous systems.