喷雾干燥-高温固相法制备纳米LiFePO4与LiFePO4/C材料及性能研究

采用喷雾干燥-高温固相法制备纳米LiFePO₄与LiFePO₄/C正极材料，用X-射线衍射，扫描电镜等对合成材料进行了表征，并对以LiFePO₄为正极的电池进行了电化学性能测试。结果表明:材料合成最佳煅烧温度为600 ℃;合成过程中由于碳对LiFePO₄晶型的生长有一定的抑制作用，相对于纯LiFePO₄材料，LiFePO₄/C材料粒径更小;并且，在此最佳合成温度下合成的LiF

Preparation and Characterization of Nano-particle LiFePO4 and LiFePO4 /C by Spray-drying and Post-annealing Method

Pure, nano-sized LiFePO4 and LiFePO4/C cathode materials were synthesized by spray-drying and postannealing method. The crystalline structure, morphology of particles were investigated by X-ray diffraction,scanning electron microscopy. The electrochemical performances of the sample were also measured. The results show that the optimum processing conditions are thermal treatment for 10 h at 600 ℃. Compared with LiFePO4,LiFePO4/C particles are smaller in size due to the inhibition of crystal growth to a great extent by the presence of carbon in the reaction mixture. The LiFePO4/C composite compound is also found to exhibit good electrode properties with discharge capacities of 139.4, 137.2, 133.5 and 127.3 mAh ·g-1 at C/5, 1C, 5C and 10C rates,respectively. In addition, it shows excellent cycle stability at different current density. Even at a high current density of 10C, the discharge capacity of 117.7 mAh·g-1 is obtained (92.4% of its initial value) with only a low capacity fading of 0.15% per cycle.