Emerging rechargeable aqueous magnesium ion battery

Recently, aqueous rechargeable batteries have played an essential role in developing renewable energy due to the merits of low cost, high security, and high energy density. Among various aqueous-based batteries, aqueous magnesium ion batteries (AMIBs) have rich reserves and high theoretical specific capacity (3833 mAh cm−3). However, for future industrialization, AMIBs still face many scientific issues to be solved, such as the slow diffusion of magnesium ions in the material structure, the desolvation penalty at electrode-electrolyte interfaces, the cost of water-in-salt electrolyte, the low voltage of traditional aqueous electrolyte, etc. And yet a comprehensive summary of the components of AMIBs is lacking in the research community. This review mainly introduces the exploration and development of AMIB systems and related components. We conduct an in-depth study of the cathode materials appropriate for magnesium ion batteries from their crystal structures, focusing primarily on layered structures, spinel structures, tunnel structures, and three-dimensional framework structures. We also investigate the anode materials, ranging from inorganic materials to organic materials, as well as the electrolyte materials (from the traditional electrolyte to water-in-salt electrolyte). Finally, some perspectives on ensuing optimization design for future research efforts in the AMIBs field are summarized.