低温合成LiFePO₄/C正极材料及其电化学性能

来源期刊：中南大学学报(自然科学版)2006年第3期

论文作者：张宝 李新海 朱炳权 王志兴 郭华军

文章页码：505 - 508

关键词：LiFePO₄/C;液相沉淀;碳热还原;前驱体

Key words：LiFePO₄/C; aqueous precipitation; carbothermal reduction; precursor

摘    要：以FeSO₄·7H₂O, NH₄H₂PO₄和H₂O₂为初始原料,通过液相沉淀制得前驱体FePO₄·2H₂O,然后通过碳热还原得到LiFePO₄/C。X射线衍射和扫描电镜分析结果表明:将FePO₄·2H₂O, Li₂CO₃与炭黑球磨2 h后再在Ar气气氛、500℃下煅烧10 h能得到无其他杂相的LiFePO₄/C材料,反应剩余的碳黑分布在LiFePO₄颗粒之间,阻碍LiFePO₄颗粒团聚,并有利于提高其电子导电率;制得的LiFePO₄/C的粒径为0.3~0.4μm,且具有良好的循环性能;以0.1C倍率电流放电的首次放电比容量为134.2 mA·h/g, 1C倍率下的放电比容量为104 mA·h/g。

Abstract: LiFePO₄/C powders were prepared by carbothermal reduction of Li₂CO₃ with FePO₄·H₂O, which was synthesized by aqueous precipitation from solution of FeSO₄·7H₂O and NH₄H₂PO₄ with H₂O₂ as the oxidizing agent. The samples were characterized by X-ray diffraction and scanning electron microscope. At first, the mixtures of FePO₄·H₂O and Li₂CO₃ and carbon were ball milled for 2 h, and then calcined at 500℃. Finally, the homogenous LiFePO₄/C was successfully synthesized with average particle size of 0.3-0.4μm. The discharge capacity of the material synthesized under the optimum conditions is 134.2 mA·h/g at 0.1C rate and 104mA·h/g at 1C rate. The residual carbon is coated on LiFePO₄, preventing the aggregation of particles and resulting in the enhancement of the material’s electronic conductivity.

基金信息：国家自然科学基金资助项目