Crystal Structures and Cathode Properties of Chemically and Electrochemically Delithiated LixNi0.5Mn0.5O2with Applications to Mg Rechargeable Batteries

Both electrochemically and chemically delithiated layered rock-salt Li(x)Ni(0.5)Mn(0.5)O(2)were successfully synthesized to investigate their crystal structures and cathode properties in the Mg rechargeable batteries. While the electrochemically delithiated LixNi0.5Mn0.5O2(x = 0.1 or 0.5) showed reversible behavior only two cycles in a Mg cell with subphase after initial discharge, the chemically delithiated Li(0.45)Ni(0.5)Mn(0.5)O(2)delivered a discharge capacity of 175 mAh g(-1)with an average potential of 2.4 V vs Mg/Mg(2+)during several cycles. The chemically delithiated structure with x = 0.45 was found to be able to intercalate Mg ions according to the Rietveld analysis for synchrotron XRD patterns and XANES spectra for discharged electrode. It was concluded that the chemically delithiated Li(0.45)Ni(0.5)Mn(0.5)O(2)provided the favored structure for Mg intercalation due to the appropriate interlayer distance.