Preparation of 4.7Â V cathode material LiNi0.5Mn1.5O4 by an oxalic acid-pretreated solid-state method for lithium-ion secondary battery

► Cathode material LiNi0.5Mn1.5O4 is obtained via a novel precursor treatment. ► Homogeneous ions distribution and controlled Mn valance state in the precursor. ► Superior cycling performance and 97.2% capacity above 4.7 V. ► Able to obtain satisfying rate performance by adjusting sintering temperature.