Spinel type lithium manganate, preparation method thereof and lithium ion battery

The spinel type lithium manganate is a spherical single crystal particle, the equivalent circle diameter deviation parameter of the single crystal particle is set as A, and A is more than or equal to 0.75 and less than or equal to 1; the equivalent circle diameter deviation parameter A is the equivalent area circle diameter DA of the single crystal particle/the maximum diameter DB of the single crystal particle; the preparation method comprises the following steps: firstly, weighing raw materials, carrying out ball milling and mixing, carrying out primary sintering on mixture powder, and crushing and dissociating an obtained lithium manganate intermediate product into dispersed lithium manganate primary powder; and adding a lithium-containing compound, and carrying out lithium supplement secondary sintering to obtain the spinel type lithium manganate. The lithium manganate single crystal has a smaller (111) crystal face area, so that the disproportionation reaction of Mn (III) is inhibited, and a battery with