Exploration of Calcium-Doped Manganese Monoxide Cathode for High-Performance Aqueous Zinc-Ion Batteries

Manganese-based cathode materials for rechargeable zinc-ion batteries (ZIBs) have drawn much interest because of their reliable safety, abundant resources, and low cost. Manganese monoxide is not considered a suitable candidate cathode due to the lack of tunneling structure but exhibits a considerable specific capacity. Therefore, investigation of the energy storage mechanism of manganese monoxide is instructive for the development of ZIBs. Here, a one-step solid-phase reaction synthesizes manganese monoxide with calcium doping. The experimental characterization and ex situ X-ray diffraction (XRD) results demonstrate that Ca dopants significantly speed up the formation of Mn defects and prolong the cycling stability. Aqueous ZIBs with Ca-doped MnO cathode can deliver a high specific capacity of 315 mAh g-1 at 0.1 A g-1 and long-term cycling performance with a significant capacity retention rate (74%) at 1 A g-1 after 5000 cycles. This work may provide a new strategy for designing high-performance cathode materials for aqueous ZIBs via heteroatom doping and help to understand its energy storage mechanism.