Enhanced electrochemical properties of surface modified limn ₂O₄ by Li-Fe composites for rechargeable lithium ion batteries

The surface modified Mn₂O₄ materials with Li-Fe composites were prepared by a sol-gel method to improve the electrochemical performance of Mn₂O₄ and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and transmission electron microscopy (TEM)-EDS. XRD results indicate that all the samples (modified and pristine samples) have cubic spinel structures, and XRD, XPS, and TEM-EDS data reveal the formation of Li(Li_xFe_xMn_2-2x)O4 solid solution on the surface of particles. For the electrochemical properties, the modified material demonstrated dramatically enhanced reversibility and stability even at elevated temperature. These improvements are attributed to the formation of the solid solution, and thus-formed solid solution phase on the surface of Mn₂O₄ particle reduces the dissolution of Mn ion and suppresses the Jahn-Teller effect.