物理化学学报 >> 2012, Vol. 28 >> Issue (08): 1899-1905.doi: 10.3866/PKU.WHXB201205152

电化学和新能源 上一篇    下一篇

锌掺杂提高LiNi1/3Co1/3Mn1/3O2正极材料的电化学稳定性

李节宾1,2, 徐友龙1, 杜显锋1, 孙孝飞1, 熊礼龙1   

  1. 1. 西安交通大学电子陶瓷与器件教育部重点实验室, 国际电介质研究中心, 西安 710049;
    2. 陕西应用物理化学研究所, 西安 710061
  • 收稿日期:2012-03-15 修回日期:2012-05-14 发布日期:2012-07-10
  • 通讯作者: 徐友龙 E-mail:ylxuxjtu@mail.xjtu.edu.cn
  • 基金资助:

    国家自然科学基金(50902109)资助项目

Improved Electrochemical Stability of Zn-Doped LiNi1/3Co1/3Mn1/3O2 Cathode Materials

LI Jie-Bin1,2, XU You-Long1, DU Xian-Feng1, SUN Xiao-Fei1, XIONG Li-Long1   

  1. 1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, P. R. China;
    2. Shaanxi Applied Physics and Chemistry Research Institute; Xi'an 710061, P. R. China
  • Received:2012-03-15 Revised:2012-05-14 Published:2012-07-10
  • Contact: XU You-Long E-mail:ylxuxjtu@mail.xjtu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation (50902109).

摘要:

通过共沉淀法与固相法相结合制备了掺锌的高稳定性Li(Ni1/3Co1/3Mn1/3)1-xZnxO2 (x=0, 0.02, 0.05)正极材料. 循环伏安(CV)曲线表明Zn掺杂使氧化峰与还原峰的电势差减小到0.09 V, 电化学阻抗谱(EIS)曲线表明Zn掺杂使电极的阻抗从266 Ω减小到102 Ω. Li+嵌入扩散系数从1.20×10-11 cm2·s-1增大到 2.54×10-11 cm2·s-1. Li(Ni1/3Co1/3Mn1/3)0.98Zn0.02O2正极材料以0.3C充放电在较高的截止电压(4.6 V)下比其他两种材料的电化学循环性能更稳定, 其第二周的放电比容量为176.2 mAh·g-1, 循环100周后容量几乎没衰减; 高温(55 °C)下充放电循环100周, 其放电比容量平均每周仅衰减0.20%, 远小于其他两种正极材料(LiNi1/3Co1/3Mn1/3O2平均每周衰减0.54%; Li(Ni1/3Co1/3Mn1/3)0.95Zn0.05O2平均每周衰减0.38%). Li(Ni1/3Co1/3Mn1/3)0.98Zn0.02O2正极材料以3C充放电时其放电比容量可达142 mAh·g-1, 高于其他两种正极材料. 电化学稳定性的提高归因于Zn掺杂后减小了电极的极化和阻抗, 增大了锂离子扩散系数.

关键词: LiNi1/3Co1/3Mn1/3O2, 高截止电压, Zn掺杂, 正极材料, 锂离子电池

Abstract:

Highly stable Li(Ni1/3Co1/3Mn1/3)1-xZnxO2 (x=0, 0.02, 0.05) cathode materials doped with Zn are synthesized by solid-state reactions with co-precipitated precursors. Cyclic voltammetry (CV) curves reveal that the potential difference between oxidation and reduction decreases to 0.09 V, and from electrochemical impedance spectra (EIS) curves, the impedance of LiNi1/3Co1/3Mn1/3O2 cathode materials is reduced from 266 to 102 Ω. The diffusion coefficients of Li+ ions in intercalation processes increase from 1.20×10-11 to 2.54×10-11 cm2·s-1. Li(Ni1/3Co1/3Mn1/3)0.98Zn0.02O2 is stable at 0.3C (constant charge/discharge) at a high cut-off potential of 4.6 V vs Li/Li+. It has a second discharge capacity of 176.2 mAh·g-1 at 0.3C and 142 mAh·g-1 at 3C, and keep almost no decay after 100 cycles at room temperature. Furthermore, its average capacity loss per cycle at 55 °C is 0.20%, which is lower compared with 0.54% for LiNi1/3Co1/3Mn1/3O2 and 0.38% for Li(Ni1/3Co1/3Mn1/3)0.95Zn0.05O2 after 100 cycles. The improved electrochemical stability of Zn-doped LiNi1/3Co1/3Mn1/3O2 is attributed to the reduced electrode polarization and impedance values, and an increased Li+ ion diffusion coefficient.

Key words: Lithium nickel cobalt manganese oxide, High cut-off voltage, Zn-doping, Cathode material, Lithium ion battery

MSC2000: 

  • O646