FePO_4为铁源时合成时间对LiFePO_4/C性能的影响

Influence of synthesis time on the properties of LiFePO_4/C composites with self-produced FePO_4 as iron source

以FeSO4.7H2O,H3PO4,H2O2和NH3.H2O为原料合成纳米化的FePO4.1.5H2O,并将Li2CO3、FePO4.1.5H2O和葡萄糖混合球磨,在800℃下通过碳热还原合成LiFePO4/C。采用X射线衍射(XRD)、扫描电镜(SEM)、循环伏安(CV)和恒电流充放电测试研究了相同温度下,不同合成时间LiFePO4/C样品的结构、形貌及电化学性能。结果表明:在800℃12 h下合成的样品具有最佳的电化学性能,在0.2C(1C=150mAh/g)倍率下放电,首次放电比容量为142.7mAh/g,经过20次充放电循环后容量基本保持不变。

Nano-FePO4·1.5H2O was synthesized with FeSO4·7H2O,H3PO4,H2O2 and NH3·H2O.LiFePO4/C cathode material was then prepared at 800 ℃ for different time by carbothermal reduction method using homogeneous mixture of Li2CO3,glucose and FePO4·1.5H2O.The structure,morphology and electrochemical properties of the samples were tested by X-ray diffraction（XRD）,scanning electronmicroscopy（SEM）,cyclic voltammetry（CV） and galvanostatic charge-discharge tests.The results showed that the LiFePO4/C composites synthesized at 800 ℃ for 12 h had optimal electrochemical properties and exhibited a initial discharge capacity of 142.7 mAh/g at 0.2 C（1 C=150 mAh/g）rate,there was almost no capacity fading after 20 cycles.