Abstract: Rechargeable Mg batteries have attracted much attention in the past decade due to their high theoretical energy density and low production cost, in which the electrolyte is the key component that determines the overall performance. Applying solid Mg-ion electrolytes brings many benefits to rechargeable Mg batteries, which can improve safety under aggressive conditions and open opportunities for new electrode applications. After extensive investigations, researchers make major breakthroughs in the solid Mg-ion electrolyte field, especially in terms of Mg-ion conductivities. However, the development of solid-state Mg batteries is still at the early stage since their stable cycling has not been achieved yet. In this review, we introduce the Mg-ion conducting properties of current solid Mg-ion electrolytes, and then summarize the performances of corresponding solid-state Mg batteries. In addition, we provide a discussion on the application potentials and future directions of each type of solid Mg-ion electrolytes that are applied in solid-state Mg batteries.

Key words: Solid Mg-ion electrolytes, Solid-state Mg batteries, Phosphates, Borohydrides, Chalcogenides, Metal-organic frameworks, Polymers