Mg batteries have high energy density, economic safety, and environmental friendliness. They show great potential as an ideal energy storage technology. This review summarizes the limitations of Mg batteries and explores the complex reactions at the Mg anode/electrolyte interface. It focuses on critical issues such as the dissolution of Mg anodes, the evolution of hydrogen gas, the formation of a passivation layer that hinders Mg²⁺ migration, and dendrite growth. To address these interface problems, the review discusses strategies to improve interface reactions. These include the structural design of Mg anodes, suitable substitute materials for the anode, and artificial solid electrolyte interphase films. Finally, it outlines the future research directions for the ideal Mg anode interfaces. The goal is to develop more efficient interface design schemes and optimization strategies to advance Mg battery technology further.

Metal-air battery is an environmental friendly energy storage system with unique open structure. Magnesium (Mg) and its alloys have been extensively attempted as anodes for air batteries due to high theoretical energy density, low cost, and recyclability. However, the study on Mg-air battery (MAB) is still at the laboratory level currently, mainly owing to the low anodic efficiency caused by the poor corrosion resistance. In order to reduce corrosion losses and achieve optimal utilization efficiency of Mg anode, the design strategies are reviewed from microstructure perspectives. Firstly, the corrosion behaviors have been discussed, especially the negative difference effect derived by hydrogen evolution. Special attention is given to the effect of anode micro-structures on the MAB, which includes grain size, grain orientation, second phases, crystal structure, twins, and dislocations. For further improvement, the discharge performance, long period stacking ordered phase and its enhancing effect are considered. Meanwhile, given the current debates over Mg dendrites, the potential risk, the impact on discharge, and the elimination strategies are discussed. Microstructure control and single crystal would be promising ways for MAB anode.

Grain growth directly influences the plasticity and strength of Mg alloys. As the grain size decreases from the microscale to the nanoscale, the plasticity of Mg alloys continually increases, whereas the strength first increases and later decreases. These trends are observed because the plastic deformation mechanism changes from dislocation–twinning dominance to grain boundary dominance. In this study, the factors influencing grain growth, such as the temperature of plastic deformation/annealing, second-phase particles and solute atoms, are examined to aid effective control of the grain size. Additionally, the mechanisms of grain growth, typically induced by strain and thermal activation, are clarified. Strain-induced grain boundary migration is attributable to the difference in the strain energy stored in adjacent grains with high-density dislocations. Heat-induced grain boundary migration is driven by the difference in the energy of the grain boundary/subgrain boundary and boundary curvature. Abnormal grain growth can be induced by anisotropy of the strain energy, anisotropy of the grain boundary mobility, depinning of the second phase and high misorientation gradient.