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化学学报
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化学学报 ›› 2006, Vol. 64 ›› Issue (12): 1223-1227. 上一篇    下一篇

研究论文

LixNi0.5Co0.5O2的态密度计算及电化学性能研究

顾大明*,1，谢颖1,2，史鹏飞1，付宏刚1,2,3   

  1. (1哈尔滨工业大学应用化学系 哈尔滨 150001)
    (2黑龙江大学化学与环境工程学院 哈尔滨 150040)
    (3吉林大学理论化学研究所理论与计算化学重点实验室 长春 130023 )
  • 投稿日期:2005-10-27 修回日期:2006-02-21 发布日期:2006-06-28
  • 通讯作者: 顾大明

Calculation on Density of States and Electrochemical Performance of LixNi0.5Co0.5O2

GU Da-Ming*,1, XIE Ying1,2, SHI Peng-Fei1, FU Hong-Gang1,2,3   

  1. (1 Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001)
    (2 School of Chemistry and Environment Engineering, Heilongjiang University, Harbin 150040)
    (3 State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry,
    Jilin University, Changchun 130023)
  • Received:2005-10-27 Revised:2006-02-21 Published:2006-06-28
  • Contact: GU Da-Ming

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>为获得综合性能更好的锂离子二次电池正极材料, 分析了Co掺杂对LixNiO2电化学性能的影响. 采用密度泛函DFT理论对LixNiO2和LixNi0.5Co0.5O2的平均放电电压和态密度进行了计算. 同时, 用共沉淀法制备了LixNiO2和LixNi0.5Co0.5O2锂离子二次电池正极材料, 并对其进行了XRD结构分析和恒流充放电测试. 实验和计算结果表明: 随锂离子嵌入正极(电池放电), 电池的电压逐渐降低, 材料的态密度峰向低能量方向移动; 与LixNiO2相比, LixNi0.5Co0.5O2的电压平台相对较高(当0.25≤x≤0.5), 而且在Li＋嵌/脱时, LixNi0.5Co0.5O2的结构变化相对较小; Co离子的掺入, 减小了NiO6八面体的畸变度, 使材料的电化学稳定性得以提高. 在钴掺杂镍酸锂体系中, NiO6和CoO6具有相互的稳定作用.

关键词: LixNi0.5Co0.5O2, 正极材料, 密度泛函理论, 态密度

In order to improve the overall performance of the Li-ion secondary battery and analyze the effect of Co-dopping on the electrochemical performance of LixNiO2 cathode, the average potential and density of states of LixNiO2 and LixNi0.5Co0.5O2 cathode materials for lithium battery were calculated under the framework of density functional theory. Meanwhile, the LiNiO2 and LiNi0.5Co0.5O2 materials were synthesized with coprecipitation method. The microstructure and electrochemical performance of the materials were characterized by XRD and galvanotatic cycling. The results of both of the tests and calculation showed that the potential was descended gradually and the density of states of the materials moved to the direction of low energy when Li ions intercalated the cathode materials (discharge). The average potential of LixNi0.5Co0.5O2 was higher than that of LixNiO2 (when 0.25≤x≤0.5), and when the Li ion intercalated/deintercalated the cathode, the change of the structure of LiNi0.5Co0.5O2 was smaller than that of LixNiO2. The distortion of the NiO6 octahedral in LixNiO2 was descended and the stability of microstructure of LixNiO2 was heightened when Co was doped into LixNiO2. CoO6 and NiO6 were mutually stabilized in LixNi0.5Co0.5O2 material.

Key words: LixNi0.5Co0.5O2, cathode, density functional theory, density of state