Electrochemical performance of Al2O3 pre-coated spinel LiMn2O4

Al2O3-coated spinel LiMn2O4 cathode materials, presintered LiMn2O4 (P-LMO), and calcined LiMn2O4 (C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn2O4 as precursors. The crystal structure, morphology, the thickness of the coating layer, and particle size of prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Malvern instruments. The average particle size of P-LMO with like-spheres (0.3 μm) is much smaller than that of C-LMO (0.5 μm). The Al2O3 layer of P-LMO can effectively reduce the charge transfer resistance and inhibit the Mn dissolution. The electrochemical performance of P-LMO is better than that of C-LMO. It is found that the LiMn2O4 cathode materials have excellent electrochemical cyclability by coated 2 mol% Al2O3 at the surface of presintered material. The initial discharge capacity of the material with 2 mol% Al2O3-coated is 114.0 mAh·g−1 at 0.1C rate and 55 °C, and the capacity retention is 87.3 % at 0.5C rate.