Enhanced cycling stability of LiMn2O4 cathode by amorphous FePO4 coating

Highlights: → FePO4 coating enhances the cycling stability of LiMn2O4. → The optimum coating content of FePO4 was found to be 3 wt.%. → FePO4 separation can effectively prevent the dissolution of Mn4+. → FePO4 modification enhances surface kinetics of LiMn2O4 material. - Abstract: The cycling performance of LiMn2O4 at room and elevated temperatures is improved by FePO4 modification through chemical deposition method. The pristine and FePO4-coated LiMn2O4 materials are characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Their cycling performances are thoroughly investigated and compared. The 3 wt.% FePO4-coated LiMn2O4 exhibits capacity losses of only 32% and 34% at room temperature and 55 deg. C, respectively, after 80 cycles, much better than those of the pristine material, 55% and 72%. The cyclic voltammograms at 55 deg. C reveal that the improvement in the cycling performance of FePO4-coated LiMn2O4 electrodes can be attributed to the stabilization of spinel structures. The separation of FePO4 between active materials and electrolyte and its interaction with SEI (solid electrolyte interphase) film are believed to account for the improved performances.