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采用了一种真空辅助沉淀法制备Fe3(PO4)2·8H2O,并以此进一步合成粒径尺寸在400 nm左右LiFePO4颗粒.研究了Fe3(PO4)2·8H2O对于磷酸铁锂的形貌、结构、电化学性能的影响.X射线衍射(XRD)结果表明,真空辅助制备的Fe3(PO4)2·8H2O具有高纯度,以此制备的LiFePO4具有高结晶度和纯度.扫描电子显微镜(SEM)结果表明,真空辅助制备的Fe3(PO4)2·8H2O具有未完全发育的颗粒,以此制备的LiFePO4均匀无硬团聚.透射电子显微镜(TEM)结果显示真空辅助制备的LiFePO4包覆一层均匀的碳.真空制备的LiFePO4显示了优异的电化学性能,在1C、10C、20C倍率下的容量分别为140、113、100 mAh·g-1.真空制备的LiFePO4的循环伏安曲线显示了小的极化电压和尖锐的氧化峰.充放电平台曲线表明真空对LiFePO4高倍率性能起到重要作用.电化学阻抗谱(EIS)计算结果显示,真空和非真空制备的LiFePO4的锂离子扩散系数分别为1.42×10-13和4.22×10-14cm2·s-1,说明真空辅助能够提高LiFePO4的扩散系数.
A vacuum assisted precipitation method was used to prepare Fe3 (PO4) 2 · 8H2O, and further LiFePO4 particles with a size of about 400 nm were synthesized.The morphology and structure of Fe3 (PO4) 2 · 8H2O , X-ray diffraction (XRD) results show that vacuum-assisted preparation of Fe3 (PO4) 2 · 8H2O with high purity, thus prepared LiFePO4 with high crystallinity and purity of the results of the scanning electron microscopy It shows that the vacuum-assisted preparation of Fe3 (PO4) 2 · 8H2O has incompletely developed particles, and the LiFePO4 prepared by this method has no hard agglomeration uniformly.Transmission electron microscopy (TEM) results show that LiFePO4 prepared by vacuum-assisted coating of uniform carbon The vacuum-prepared LiFePO4 showed excellent electrochemical performance with capacities of 140, 113 and 100 mAh · g-1 at 1C, 10C and 20C respectively.The cyclic voltammetry of LiFePO4 prepared by vacuum showed a small electrode Voltage and sharp oxidation peak.The curve of charging and discharging platform shows that the vacuum plays an important role in the high rate performance of LiFePO4.The electrochemical impedance spectroscopy (EIS) results show that the lithium ion diffusion coefficients of LiFePO4 prepared by vacuum and non-vacuum are 1.42 × 10-13 and 4 .22 × 10-14cm2 · s-1, indicating that vacuum assisted LiFePO4 can improve the diffusion coefficient.