Breaking the thermal barrier: Amorphous oxide cathodes and electrolyte engineering for practical room-temperature magnesium-ion batteries

Magnesium-ion batteries (MIBs) represent a promising beyond-lithium energy storage technology due to the high volumetric capacity, natural abundance, and intrinsic safety of magnesium metal. However, the practical realization of room-temperature MIBs has long been hindered by a persistent “thermal bottleneck” sluggish Mg 2+ solid-state diffusion and irreversible anode passivation. This review provides a critical analysis of recent breakthroughs that are dismantling this barrier, focusing on two synergistic frontiers: amorphous oxide cathodes and advanced electrolyte engineering. We highlight the paradigm-shifting role of structurally disordered cathodes, exemplified by Mg 0 . 27 Li 0 . 09 Ti 0 . 11 Mo 0 . 22 O, where engineered free volume enables percolation-assisted Mg 2+ transport at ambient temperature. Concurrently, we examine the evolution of non-corrosive electrolytes from early Grignard-based systems to modern weakly coordinating anions that support reversible Mg plating and high-voltage operation. The hybrid-ion approach, which decouples anode and cathode kinetics using Li + or Na + as charge carriers, is also evaluated as a practical pathway to high energy and power densities. Further, we discuss the integration of computational modeling, advanced characterization, and prototype validation in accelerating material discovery. Finally, we address synthesis scalability, device integration challenges, and the evolving commercial landscape, outlining a research roadmap toward the commercialization of room-temperature MIBs for grid storage, electronics, and beyond.