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

Abstract 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 LiLa 0.01 Mn 1.99 O 3.99 F 0.01 . XRD data indicate that all samples exhibit the same pure spinel phase, and LiLa 0.01 Mn 1.99 O 3.99 F 0.01 and LiLa 0.01 Mn 1.99 O 4 samples have a better crystallinity than LiMn 2 O 4 . SEM images indicate that LiLa 0.01 Mn 1.99 O 3.99 F 0.01 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 LiMn 2 O 4 , LiLa 0.01 Mn 1.99 O 4 , and LiLa 0.01 Mn 1.99 O 3.99 F 0.01 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.