LiFePO薄膜的制备及其性质研究

Preparation of LiFePO_4 thin films by sol-gel technique

以醋酸锂、硝酸铁、磷酸二氢铵为原料,采用溶胶-凝胶法制备锂离子薄膜电池正极材料LiFePO薄膜。用X射线衍射、红外光谱、扫描电镜等分析了薄膜的物相和表面形貌。用循环伏安法扫描、恒电流充放电和交流电阻抗技术研究LiFePO薄膜的电化学性能。结果表明该法于700℃制备的LiFePO4薄膜比容量为145mAh·g-1,经20次循环后的每次循环容量损失为0.07%,薄膜具有良好的循环性能。交流阻抗表明锂离子在薄膜中的扩散系数为4.2×10-14cm·2s-1,说明锂离子在薄膜中具有较快的扩散速度。

LiFePO4 thin films were prepared by sol-gel technique. The phase identification and surface morphology were investigated by X-ray diffraction and scanning electron microscopy, The electrochemical properties of the thin films were carried out by cyclic voltammetry, charge-discharge experiments and impedance spectroscopy in 1 mol·L^-1 LiPF6/EC- DMC solution using lithium metal as both counter and reference electrodes. The films prepared by this method are of puce LiFePO4 phase. The film annealed at 700 ℃ has the capacity of 145 mAh/g, and the capacity loss per cycle is 0.07% after being cycled 20 times, The AC impedance show that diffusion cofficience is about 4.2 × 10^-14cm^2·s^-1. indicating that the fast transform in thin film electrode of LiFePO4.