High temperature cycleability of spherical spinel LiMn₂O₄ with Al-doped surface

The spherical Mn₃O₄ was prepared by a controlled crystallization process, and the spherical spinel LiMn₂O₄ was produced by the following procedure: the surface of the spherical Mn₃O₄ was coated with Al(OH)₃, then mixed with LiOH and sintered. The structure and performances of the above material were studied by SEM, XRD, EDS etc. SEM analysis showed that the Al(OH)₃ was uniformly coated on the surface of spherical Mn₃O₄. XRD and EDS analysis's indicated that the Al³⁺ ions occupied the sites of manganese and Al content of its surface was higher than the average value, indicating that the aluminum was only enriched on the surface of the particles, e.g. the surface doping. Specific capacity of spherical LiMn₂O₄ decreased after the doping, but its cycle ability at 55°C was improved. Its capacity retention for the spinel LiMn₂O₄ doped with 6%A1 at 50^th cycle at 55°C increased from 68.3% to 79.0%. It means that the surface doping of aluminum is an effective way to improve the elevated temperature performances of spherical spinel LiMn₂O₄.