Modified lithium manganate as well as preparation method and application thereof

The invention belongs to the technical field of lithium batteries, and particularly relates to modified lithium manganate as well as a preparation method and application thereof. The invention provides modified lithium manganate. The modified lithium manganate has a molecular formula as shown in a formula I: Li < a > Mn < 2-b > Al < b > F < c > O < 4-c >, wherein 1.05 < = a < = 1.12, 0.04 < = b < = 0.1, and 0.01 < = c < = 0.04. Aluminum and fluorine are doped into lithium manganate, oxygen is partially replaced by fluorine in modified lithium manganate, the strength of chemical bonds is improved, and the high-temperature performance of the modified lithium manganate is improved. Al < 3 + > and F binary ions in the modified lithium manganate enable the main structure of the lithium manganate to keep stable, Al < 3 + > enters the lattice part of the modified lithium manganate to replace the Mn < 3 + > position, the lattice parameter of the lithium manganate spinel is reduced, meanwhile, the relative content