Morphology-controllable synthesis of LiMn_2O_4 particles as cathode materials of lithium batteries

摘要

We reported a new method for the preparation of morphology-controllable LiMn_2O_4 particles. In this method, dimension-different MnO_2 nanowires synthesized hydrothermally by adjusting the reaction temperature were used as the precursor. The morphology and structure of the resulting products were characterized with scanning electron microscope and X-ray diffraction, and the performances of the prepared LiMn_2O _4 samples as cathode material of lithium batteries were investigated by cyclic voltammetry and galvanostatic charge/discharge test. The results indicate that the morphology of LiMn_2O_4 transforms from tridimensional particle (TP) to unidimensional rod (UR) through quadrate lamina (QL) with increasing the diameter and length of MnO_2 nanowires. Although the cyclic stabilities of LiMn_2O_4-TP, LiMn _2O_4-QL, and LiMn_2O_4-UR are very close (the 0.1 C capacity after 50 cycles is 101, 93, and 99 mAh g~(-1) at 25 C, and 84, 78, and 82 mAh g~(-1) at 50 C, respectively), LiMn _2O_4-QL delivers much higher rate capacity (about 70 mAh g~(-1) at 5 C and 30 mAh g~(-1) at 10 C) than LiMn _2O_4-TP and LiMn_2O_4-UR (about 20 mAh g~(-1) at 5 C, 3 mAh g~(-1) at 10 C, 25 mAh g~(-1) at 5 C, and 3 mAh g~(-1) at 10 C).