Electrochemical performance of LaF3-coated LiMn2O4 cathode materials for lithium ion batteries

The cycle performance of spinel LiMn2O4 at 25 and 55 °C is improved by LaF3 modification via a chemical deposition method. The physical and electrochemical performances of pristine and LaF3-coated LiMn2O4 cathode materials are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements. The coated LiMn2O4 with 2.92 wt% LaF3 (LaF3-3-LMO) displays capacity retentions of 90.1% and 84.2% at 25 and 55 °C, respectively, after 100 cycles, much higher than those of pristine LiMn2O4, 72.7% and 54.8%. The concentration of manganese dissolved from LaF3-3-LMO in electrolyte is much lower than that from pristine LiMn2O4. The analysis of AC impedance indicates that the charge transfer resistance (Rct) and the increase of Rct for LaF3-3-LMO during cycling are much lower than those for pristine LiMn2O4. The significantly improved electrochemical performance of the LaF3-coated LiMn2O4 can be attributed to the reduction of manganese dissolution in electrolyte and charge transfer resistance with the help of LaF3 coating.

Cycle performance of spinel LiMn2O4 at elevated temperature is greatly improved by surface modification of LaF3.Figure optionsDownload as PowerPoint slideHighlights
► LaF3-coated spinel LiMn2O4 was prepared by a chemical deposition method.
► Spinel LiMn2O4 powders are covered by nanoparticles of LaF3.
► This coated sample exhibits much better cycle performance than bare LiMn2O4.
► The dissolution of Mn from LiMn2O4 decreases greatly with the help of LaF3 coating.
► LaF3-coated LiMn2O4 shows lower charge transfer resistance than bare LiMn2O4.