物理化学学报 >> 2014, Vol. 30 >> Issue (5): 866-872.doi: 10.3866/PKU.WHXB201403041

电化学和新能源 上一篇    下一篇

真空辅助法合成Fe3(PO42·8H2O及对LiFePO4/C结构、形貌和电化学性能的影响

任建新1, 胡有坤1,郭孝东1, 唐艳1, 钟本和1, 刘恒2   

  1. 1 四川大学化学工程学院, 成都610065;
    2 四川大学材料科学与工程学院, 成都610065
  • 收稿日期:2013-12-16 修回日期:2014-03-04 发布日期:2014-04-25
  • 通讯作者: 郭孝东 E-mail:xiaodong2009@scu.edu.cn
  • 基金资助:

    四川大学青年基金(2011SCU11081)及教育部高校博士学科点科研基金(20120181120103)资助项目

Vacuum-Assisted Synthesis of Fe3(PO4)2·8H2O and Its Influence on Structure, Morphology and Electrochemical Performance of LiFePO4/C

REN Jian-Xin1, HU You-Kun1, GUO Xiao-Dong1, TANG Yan1, ZHONG Ben-He1, LIU Heng2   

  1. 1 College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China;
    2 College of Materials Science and Engineering, Sichuan University, Chengdu 610065, P. R. China
  • Received:2013-12-16 Revised:2014-03-04 Published:2014-04-25
  • Supported by:

    The project was supported by the Fund for Young Scientists of Sichuan University, China (2011SCU11081) and Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20120181120103).

摘要:

采用了一种真空辅助沉淀法制备Fe3(PO42·8H2O,并以此进一步合成粒径尺寸在400 nm 左右LiFePO4颗粒. 研究了Fe3(PO42·8H2O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(PO42·8H2O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(PO42·8H2O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4.22×10-14 cm2·s-1,说明真空辅助能够提高LiFePO4的扩散系数.

关键词: Fe3(PO42·, 8H2O, LiFePO4/C, 真空辅助, 沉淀, 高倍率

Abstract:

A vacuum-assisted precipitation method was used to synthesize Fe3(PO4)2·8H2O (FP). The FP was then used to synthesize carbon-coated LiFePO4 (LFP/C) particles. The influence of FP on the structure, morphology, and electrochemical performance of LFP was investigated. The X-ray diffraction (XRD) patterns and molar ratio of Fe to P showed that the FP which was produced using a vacuum-assisted method was of high purity and gave highly crystalline, impurity-free LFP. Scanning electron microscopy (SEM) showed that the FP contained undeveloped particles. The undeveloped FP results in uniform LFP/C particles, without agglomeration. Transmission electron microscopy (TEM) showed that the LFP particles were coated with a homogeneous carbon layer. The LFP/C showed excellent discharge capacities of 140, 113, and 100 mAh·g-1 at 1C, 10C, and 20C rates, respectively. The cyclic voltammograms (CVs) of LFP showed a low polarization voltage and sharp redox peaks. The charge-discharge platform curves showed that LFP had an excellent high-rate capability. Electrochemical impedance spectroscopy (EIS) tests showed that the lithium-ion diffusion coefficients of LFP/C produced with and without vacuum assistance were 1.42×10-13 and 4.22×10-14 cm2·s-1, respectively, proving that vacuum assistance can improve the diffusion coefficients of LFP/C.

Key words: Fe3(PO42·, 8H2O, LiFePO4/C, Vacuum-assistance, Precipitation, High rate

MSC2000: 

  • O646