Progress in rechargeable magnesium battery technology

A new generation of rechargeable magnesium batteries with improved performance is presented. The cathodes are Chevrel phases of the Mo6S8-ySey (y = 0, 1, 2) type. The partial substitution of S by Se in these materials enables a very fast and reversible Mg intercalation at capacities close to the theoretical values, due to structural changes in the Mg insertion sites and increase in the polarizability of the anionic framework of the host. New electrolyte solutions with electrochemical windows wider than 3 V are also briefly reported.