Structure and Characteristic of LiFePO4 Cathode Material Synthesized in the Mixed Solvent Environment

In this paper, LiFePO4 samples were synthesized in the water/ethanol mixture solvent environment with different volume ratio of water/ethanol, and the effects of different solvent environment (different water/ethanol ratio) on the morphology, the crystal structure and the cell performances were studied in detail. The prepared samples were investigated comparatively by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and various electrochemical testing techniques. The results showed that the water/ethanol ratio seriously affected the crystal structure, the micro-morphologies and the electrochemical properties of the resulting LiFePO4-based electro-active material. And the growth of [010] direction of LiFePO4 crystal was limited with the increase of alcohol proportion in the mixed solvent, while the size of obtained particles became small in the same process. In addition, LiFePO4 samples obtained at high alcohol content presented the improved specific capacity and rate performances. Specially, the LFP-D electrode displayed the discharge capacity of 153.2 mAh·g−1 at the rate of 0.1 C and the improved rate performance of 150.6, 143.6, 133.8, 121.4, 99.5 and 78.2 mAh·g−1 at 0.2 C, 0.5 C, 1 C, 2 C, 5 C and 10 C, respectively.