Rechargeable Mg-Li hybrid batteries: status and challenges

A magnesium-lithium (Mg-Li) hybrid battery consists of an Mg metal anode, a Li+ intercalation cathode, and a dual-salt electrolyte with both Mg2+ and Li+ ions. The demonstration of this technology has appeared in literature for few years and great advances have been achieved in terms of electrolytes, various Li cathodes, and cell architectures. Despite excellent battery performances including long cycle life, fast charge/discharge rate, and high Coulombic efficiency, the overall research of Mg-Li hybrid battery technology is still in its early stage, and also raised some debates on its practical applications. In this regard, we focus on a comprehensive overview of Mg-Li hybrid battery technologies developed in recent years. Detailed discussion of Mg-Li hybrid operating mechanism based on experimental results from literature helps to identify the current status and technical challenges for further improving the performance of Mg-Li hybrid batteries. Finally, a perspective for Mg-Li hybrid battery technologies is presented to address strategic approaches for existing technical barriers that need to be overcome in future research direction.