Structure and electrochemical properties of LiLaxMn2-xO4 cathode material by the ultrasonic-assisted sol-gel method

Powders of spinel LiLaxMn2-xO4 were successfully synthesized by the ultrasonic-assisted sol-gel (UASG) method. The structure and properties of LiLaxMn2-xO4 were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscopy (SEM), galvanostatic charge-discharge test, and cyclic voltammetry (CV). XRD results show that the La3+ can partially replace Mn3+ in the spinel and the doped materials with La3+ have a larger lattice constant compared with pristine LiMn2O4. FT-IR indicates that the absorption peak of Mn3+−O and Mn4+− O bonds has a red and blue shift with the increase of doping lanthanum in LiLaxMn2-xO4, respectively. The charge-discharge test exhibits that the initial discharge capacity of LiLaxMn2-xO4 drops off, and the capacity retention increases gradually at C/5 discharge rate with the increase of doping lanthanum, and LiLa0.01Mn1.99O4 has a higher discharge capacity and a better cycling performance at 1C discharge rate. CV reveals that the doping La3+ is beneficial to the reversible extraction and intercalation of Li+ ions.