Recent advances in rechargeable aqueous magnesium-ion batteries

Aqueous rechargeable batteries have received widespread attention due to their advantages like low cost, intrinsic safety, environmental friendliness, high ionic conductivity, ease of operation, and simplified manufacturing in air. Magnesium (Mg), characterized by its abundant resources, cost-effectiveness, stability, non-toxicity, high volumetric capacity, and low redox potential, has captured scientific interest as a potential option for rechargeable batteries. Initially, rechargeable magnesium-ion batteries predominantly utilized organic electrolytes, which had drawbacks such as high cost, strong corrosiveness, poor cycling performance, and low conductivity. Therefore, researchers are starting to shift their focus towards cost-effective, safe, and environmentally friendly aqueous Mg-ion batteries (AMIBs). Nonetheless, there are significant challenges in AMIBs like low specific capacities and energy densities, which need to be overcome for practical applications. To inspire further research, this work provides a comprehensive overview of recent advancements in AMIBs, covering topics such as electrolytes, cathode materials, anode materials, and full cells. Through this work, we aim to show the great potential of AMIBs, especially a full battery based on Mg metal anodes. Recent breakthroughs in Mg-ion electrode materials and electrolytes have raised hopes for the realization of high-performance mild AMIBs, though they are still in their infancy. This work provides a comprehensive overview of recent advancements in mild aqueous Mg-ion batteries, covering their significant components such as electrolytes, cathode materials, intercalation anode materials, Mg metal anodes, and the full cell.