Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (03): 223-228.DOI: 10.6023/A1107201 Previous Articles     Next Articles

Full Papers

Na 掺杂对LiFePO4/C 复合正极材料的结构和倍率性能的影响

陆晓挺, 李东林, 樊小勇, 赵鹏, 苟蕾, 李严, 李倩, 王静   

  1. 长安大学材料科学与工程学院 长安大学能源材料与器件研究所 西安 710064
  • 投稿日期:2011-07-20 修回日期:2011-09-28 发布日期:2011-10-27
  • 通讯作者: 李东林
  • 基金资助:

    国家自然科学基金(Nos. 20903016, 21073021, 21103013)、教育部高等学校科学技术重大项目培育资金项目(No. 708084)和中央高校基本科研业务费专项资金(Nos. CHD2010ZD008, CHD2010JC006, CHD2011ZD007)资助项目.

Study on Structure and Rate Performance of LiFePO4/C Composite Cathode Material via Na Doping

Lu Xiaoting, Li Donglin, Fan Xiaoyong, Zhao Peng, Gou Lei, Li Yan, Li Qian, Wang Jing   

  1. Laboratory of Energy Materials and Devices, School of Materials and Engineering, Chang’an University, Xi’an 710064
  • Received:2011-07-20 Revised:2011-09-28 Published:2011-10-27
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 20903016, 21073021, 21103013), Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (No. 708084), Fundamental Research Funds for the Central Universities (Nos. CHD2010ZD008, CHD2010JC006, CHD2011ZD007).

Li0.97Na0.03FePO4/C composite cathode material was prepared by a simple wet chemistrycarbothermal reduction method using Fe(NO3)3, LiNO3, NH4H2PO4 and NaNO3 as starting materials. The structure and charging-discharging rate properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and charge-discharge test. Furthermore, the kinetics of lithium-ion extraction and insertion at LiFePO4/C were evaluated from cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS). The results indicate that the Li0.97Na0.03FePO4 solid-solution with olivine structure is obtained. Na-doping enlarges one-dimensional lithium-ion diffusion pathway in the olivine structure. Consequently, the materials exhibit a decrease in the charge transfer resistance by 67% and an increase in the lithium-ion diffusion coefficient by 3 ~ 4 times. The initial discharge capacities of Li0.97Na0.03FePO4/C sample at the rate of 0.1 C and 2 C are 152 mAh·g-1 and 109 mAh·g-1, respectively, which increase 4.83% and 62.69% compared with that of un-doped LiFePO4/C.

Key words: lithium-ion battery, LiFePO4, Na doping, lithium-ion diffusion coefficient, rate charge-discharge