Exploration of Amorphous V ₂ O ₅ as Cathode for Magnesium Batteries

Abstract Development of energy storage technologies that can exhibit higher energy densities, better safety, and lower supply‐chain constraints than the current state‐of‐the‐art Li‐ion batteries is crucial for our transition into sustainable energy use. In this context, Mg batteries offer a promising pathway to achieve superior volumetric energy densities than Li‐ion but require the development of positive electrodes (cathodes) that exhibit high energy densities at a reasonable power performance. Notably, amorphous materials that lack long range order can exhibit “flatter” potential energy surfaces than crystalline frameworks, possibly resulting in faster Mg ²⁺ motion. Here, we use a combination of ab initio molecular dynamics (AIMD), and machine learned interatomic potential based calculations is used to explore amorphous‐V ₂ O ₅ as a potential cathode for Mg batteries. Using an AIMD‐generated dataset, we train and validate moment tensor potentials that can accurately model amorphous‐V ₂ O ₅ Importantly, we find a ≈7 (5) orders of magnitude higher Mg ²⁺ diffusivity in amorphous‐MgV ₂ O ₅ than crystalline‐Mg _x V ₂ O ₅ (thiospinel‐Mg _x Ti ₂ S ₄ ), which is directly attributable to the amorphization of the structure, along with a 10‐14% drop in the average Mg intercalation voltage. Our work highlights the potential of amorphous‐V ₂ O ₅ as a cathode that can exhibit both high energy and power densities, resulting in the practical deployment of Mg batteries.