Method for improving performance of lithium manganate cathode material

A method for improving the performance of a lithium manganate cathode material comprises the following steps: (1), washing lithium manganate with a granularity D50 being equal to or smaller than 35 [mu]m by distilled water to remove impurities, and then, dewatering and drying to obtain an impurity-removed lithium manganate product; (2), adding the impurity-removed lithium manganate product into an anionic compound, forging at the constant temperature of 400-600 DEG C for 2-8h after uniformly mixing, then continuously raising the temperature to 700-1000 DEG C, forging at the constant temperature for 7-20h, cooling to a room temperature, and grinding to the granularity D50 being equal to or smaller than 35 [mu]m to obtain the lithium manganate cathode material. According to the invention, the first discharge capacity specific capacity of the lithium manganate cathode material prepared by the method can reach 125mAh/g, and the discharge capacity retention rate of the lithium manganate cathode material being cycled for 50 times at the high temperature of 55 DEG C reaches 95% above. The adoption of the secondary forging of the lithium manganate product in the method can improve the material capacity, enhance the structural stability and improve the material performance. The method adopting simple technology and mild conditions is suitable for massive industrial production.