水热法一步合成磷酸铁锂及其性能研究

为优化液相法一步制备磷酸铁锂（LiFePO₄）技术,以七水合硫酸亚铁、磷酸二氢铵、一水合氢氧化锂为原料,通过添加十二烷基苯磺酸钠（SDBS）作为表面活性剂,采用液相水热法合成技术,一步合成了LiFePO₄正极材料。研究了水热法一步合成技术对LiFePO₄材料的组成、结构、形貌、粒度等的影响,通过电感耦合等离子体发射光谱仪（ICP-OES）、X射线衍射仪（XRD）、扫描电镜（SEM）、粒度分析仪等对材料进行了表征分析,并测试了材料的电化学性能。研究结果表明,合成得到的LiFePO₄材料为微米级球形颗粒形貌的正交晶系非化学计量比的Li_1.02Fe_0.994PO₄材料。电化学性能测试结果表明,在0.1C倍率下首次充、放电比容量分别为162.0、159.9 mA·h/g,库伦效率达到98.7%、倍率性能（以1C/0.1C保持率计）为92.3%,0.1C倍率循环100次容量保持率为96.4%,展现出良好的电化学性能。

Study on the one-step hydrothermal synthesis of LiFePO4 and its properties

In order to optimize the one-step preparation technology of lithium iron phosphate （LiFePO₄） by liquid phase me-thod,LiFePO₄ cathode material was synthesized from ferrous sulfate,ammonium dihydrogen phosphate and lithium hydroxide by adding sodium dodecylbenzene sulfonate（SDBS） as surfactant.The effect of one-step hydrothermal synthesis technology on the composition,structure,morphology and particle size of LiFePO₄ was studied.The material was characterized by ICP,XRD,SEM and particle size analyzer,and its electrochemical properties were tested.The results show that Li_1.02Fe_0.994PO₄ with micron spherical particle morphology has been synthesized.The first charge-discharge specific capacities at 0.1C ratio are 162.0 mA·h/g and 159.9 mA·h/g,respectively.The Coulomb efficiency is 98.7% and the rate performance（in terms of 1C/0.1C holding rate） is 92.3%,and the holding rate of capacity was 96.4% at 0.1C ratio after 100 times cycle.It showed good electrochemical performance.