Intercalation of Mg-ions in layered V2O5 cathode materials for rechargeable Mg-ion batteries

The development of functioning rechargeable Mg-ion batteries is still in its early stage, and a coarse screening of suitable cathode materials is still on-going. Within the intercalation-type cathodes, layered crystalline materials are of high interest as they are known to perform well in Li-ion intercalation batteries and are also increasingly being explored for Na-ion batteries. Here, we present an investigation of the layered material orthorhombic V2O5, which is a classical candidate for an ion-intercalation material having a high theoretical capacity1. We present discharge-curves for the insertion of magnesium, and investigate the degradation as a function of cycle number. Furthermore, in an attempt to separate degradation associated with the cathode and the anode, effects of exchanging anode and electrolyte were investigated. Hereby, up to 50% of the cathode capacity was regained on the subsequent discharge. This indicates that the degradation is highly associated with formation of ion-blocking layers on the anode.