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化学学报
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化学学报 ›› 2005, Vol. 63 ›› Issue (19): 1853-1856. 上一篇    

研究简报

球形尖晶石LiMn2O4掺杂钇的性能研究

何向明*，蒲薇华，蔡砚，王晓青，姜长印，万春荣   

  1. (清华大学核能与新能源技术研究院材料化学实验室 北京 102201)
  • 投稿日期:2004-01-25 修回日期:2005-07-06 发布日期:2010-12-10
  • 通讯作者: 何向明

Yttrium Doping of Spherical Spinel LiMn2O4 Cathode Materials for Lithium Ion Batteries

HE Xiang-Ming*, PU Wei-Hua, CAI Yan, WANG XIAO-Qing, JIANG Chang-Yin, WAN Chun-Rong   

  1. (Materials Chemistry Laboratory, Institute of Nuclear Energy & New Energy Technology,
    Tsinghua University, Beijing 102201)
  • Received:2004-01-25 Revised:2005-07-06 Published:2010-12-10
  • Contact: HE Xiang-Ming

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利用控制结晶方法, 在前驱体碳酸锰中共沉淀掺杂适量的钇, 得到球形掺杂钇的碳酸锰, 在540 ℃预烧后, 与锂盐一起焙烧, 可以得到高活性的掺钇球形尖晶石LiMn2O4. XRD分析表明, 产物中无杂相产生. 研究表明, 掺杂钇与掺杂其它金属离子的特性不一样, 钇具有催化特性, 掺杂钇可以提高尖晶石LiMn2O4中锰的活性. 掺钇使得更多的Mn3＋参加电化学反应, 增加容量; 但同时也使更多的锰与电解液反应, 造成锰的溶解, 容量损失. 掺钇量越多, 锰的溶解量越大. 因此, 合适的掺杂量对于保证产品良好的电化学性能至关重要. 实验证明, 掺钇0.5%的产品Li(Y0.005Mn0.995)2O4具有较好的电化学性能. 其常温初始比容量为130 mAh•g－1, 大于纯相的锰酸锂的125 mAh•g－1, 100次循环后比容量为120 mAh•g－1, 容量保持率为92.3%.

关键词: 尖晶石LiMn2O4, 掺杂, 钇, 锰溶解, 锂离子电池

A controlled crystallization process was proposed for synthesis of yttrium doped spherical spinel LiMn2O4 particles. Its successful preparation started with a carefully controlled crystallization of yttrium doped MnCO3 by co-precipitation of MnSO4 and YCl3 with NH4HCO3 and NH3•H2O. Mn2O3 was obtained by heating MnCO3 and mixed with Li2CO3 to produce yttrium doped spinel LiMn2O4. As-prepared samples were characterized by SEM and XRD. Dissolution of manganese in electrolyte was also investigated, resulting in that the dissolution was enhanced by dopant of yttrium. The more yttrium, the larger dissolution, indicating that manganese was activated by yttrium. The activation of manganese led to both enhancement of electrochemical activity and reactivity with electrolyte of manganese. The former improved the elec-trochemical performance of spinel LiMn2O4. Contrarily, the latter worsened its performance. 0.5% was a proper amount of doping, and such yttrium doped sample Li(Y0.005Mn0.995)2O4 had an initial capacity of 130 mAh•g－1 over that of un-doped one with the capacity retention to reach 92.3% exceeding that of un-doped one at 100th cycle.

Key words: spinel LiMn2O4, doping, yttrium, dissolution of manganese, Li-ion battery