MAGNESIUM INSERTION BATTERIES - AN ALTERNATIVE TO LITHIUM

Li+, Na+ and Mg2+ insertion in five hydrated, layered vanadium bronzes, LiV3O8, NaV3O8, KV3O8, Mg(V3O8)(2) and Ca(V3O8)(2), was studied with regard to their use as electroactive materials in ion-transfer batteries. The behaviour of all bronzes is similar: variation in the content of bound lattice water in the bronzes is responsible for a difference in the electrochemical properties of the same material dried at different temperatures. The presence of this water is essential; the amount of H2O in the NaV3O8 .(H2O)(y) and Mg(V3O8)(2) .(H2O)(y) bronzes has been optimized to get the best electrochemical performance. The specific charges of both optimized bronzes calculated from the first discharge are about 330 and 150 mAh/g for Li+ and Mg2+ insertion, respectively.