Design of novel oxychloride cathodes for rechargeable Mg-ion batteries

Rechargeable Mg-ion batteries are exciting multivalent, Earth-abundant alternatives to Li-ion batteries. Divalent Mg2+ ions shuttle twice the charge per ion as conventional Li+ or Na+ ions offering a route to batteries with significantly higher energy density. However, the high charge density of Mg2+ means diffusion through transition metal oxide cathode materials with ‘hard’ O2- anions is typically very slow. To overcome this, we propose to investigate novel transition metal oxychlorides with layers of ‘softer’ chloride ions which introduce a van der Waals gap to facilitate Mg intercalation. We will take a powerful combined experimental-machine-learning-modelling approach to understand how to maximise the diffusivity of Mg2+ in these cathodes, ultimately enabling us to realise the full capacity benefits of the divalent Mg2+ ion.