MxMn8O16 (M = Ag or K) as promising cathode materials for secondary Mg based batteries: the role of the cation M

AgxMn8O16 (Ag-OMS-2) and KxMn8O16 (K-OMS-2) were investigated as high voltage cathode materials for Mg based batteries. Both MxMn8O16 materials delivered high initial capacities (>180 mA h g(-1)), and KxMn8O16 showed high cycle stability with a reversible capacity of >170 mA h g(-1) after 20 cycles.