Magnesium alloys are light structural materials and promising anode candidates for Mg-air batteries. However, application of Mg-air batteries is limited by poor performance at large current density and severe H₂ generation side reactions. In this study, we pioneered magnesium-rare earth Mg₃RE (RE=La, Ce, Pr and Nd) intermetallic compounds as anodes to provide higher power density and more stable discharge performance. Especially, Mg₃Pr alloy exhibits high discharge voltage of 0.91 V and peak power density of 54.4 mW cm⁻² at 60 mA cm⁻² with anodic efficiency of 60%, far better than other Mg alloys. We reveal an activation mechanism of Mg₃RE-based anodes during discharge, which significantly accelerates mass transfer process as well as enhances discharge activity. The results improve the performance of high-power Mg-air batteries and promote the value-added application of abundant rare earth elements such as Ce and La.

Magnesium hydride (MgH₂) is a high-capacity anode material for lithium ion batteries, which suffers from poor cycling stability. In this study, we describe a thermal plasma-based approach to prepare homogeneous MgH₂/C nanocomposites with very high cycling stability. In this process, magnesium evaporation is coupled with carbon generation from the plasma decomposition of acetylene, leading to a homogeneous Mg/C nanocomposite, which can be easily converted to MgH₂/C by hydrogenation. The MgH₂/C nanocomposite achieves a high reversible capacity of up to 620 mAh·g^–1 after 1, 000 cycles with an ultralow decay rate of only 0.0036% per cycle, which represents a significantly improved performance compared to previous results.