Synthesis and physicochemical properties of LiLa0.01Mn1.99O3.99F0.01 cathode materials for lithium ion batteries

Spinel lithium manganese oxide cathode materials were synthesized using the ultrasonic-assisted sol-gel method. The synthesized samples were investigated by differential thermal analysis (DTA) and thermogravimetry (TG), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and the charge-discharge test. TG-DTA shows that significant mass loss occurs in two temperature regions during the synthesis of LiLa0.01Mn1.99O3.99F0.01. XRD data indicate that all samples exhibit the same pure spinel phase, and LiLa0.01Mn1.99O3.99F0.01 and LiLa0.01Mn1.99O4 samples have a better crystallinity than LiMn2O4. SEM images indicate that LiLa0.01W1.99O3.99F0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution. The charge-discharge test reveals that the initial capacities of LiMn2O4, LiLa0.01Mn1.99O4, and LiLa0.01Mn1.99O3.99F0.01 are 130, 123, and 126 mAh.g(-1), respectively, and the capacity retention rates of the initial value, after 50 cycles, are 84.8%, 92.3%, and 92.1%, respectively. The electrode coulomb efficiency and CV reveal that the electrode synthesized by the ultrasonic-assisted sol-gel (UASG) method has a better reversibility than the electrode synthesized by the sol-gel method.