物理化学学报 >> 2000, Vol. 16 >> Issue (08): 735-740.doi: 10.3866/PKU.WHXB20000812

研究论文 上一篇    下一篇

α-Fe2O3在LiOH水溶液中的锂化行为

李明, 杨华铨   

  1. 北京大学化学系,北京 100871
  • 收稿日期:1999-12-23 修回日期:2000-04-07 发布日期:2000-08-15
  • 通讯作者: 杨华铨

Lithiation Behavior of α-Fe2O3 in LiOH Electrolyte Solution

Li Ming, Yang Hua-Quan   

  1. Department of Chemistry,Peking University,Beijing 100871
  • Received:1999-12-23 Revised:2000-04-07 Published:2000-08-15
  • Contact: Yang Hua-Quan

摘要:

用循环伏安和红外光谱法对α-Fe_2O_3在室温LiOH溶液中的锂化行为进行研究.采用X射线衍射(XRD)、电感偶合等离子体光源的原子发射光谱(ICP)对α-Fe_2O_3电极在第一、二次循环中不同时段进行了跟踪分析测量.实验结果揭示: α-Fe_2O_3能进行少量锂化;大量的α-Fe_2O_3在第一次放电和充电后反应生成Fe_3O_4;之后,Fe_3O_4的锂化行为不可避免地为Fe的析出、氧化反应所限制,但在用KOH作电解质溶液的对比实验时发现:α-Fe_2O_3在LiOH溶液中的充放电行为与它在KOH溶液中是不同的,主要表现为,1)在LiOH溶液中,锂化和Fe析出、氧化反应协调的结果是其充放电曲线平台高度比在同碱度 KOH溶液中降低了 100 mV左右, 2)与 K+对比, Li+的插入反应促进了α-Fe_2O_3到Fe_3O_4的转化.

关键词: α-Fe2O3, Fe3O4, 水溶液锂离子电池, Ni-Fe电池

Abstract:

The lithiation behavior of a-Fe_2O_3, is investigated at ambient-temperature in LiOH solutions by methods of cyclic voltammetry, IR and tracking XRD and ICP analyses. The results reveal that lithiation can take place to a small extent in α-Fe_2O_3 and its electrochemically synthesized product is Fe_3O_4 but lithiation process is limited by the unavoidable extrusion of iron in alkaline solutions. It is suggested that Li+ intercalation promotes iron's extrusion from α-Fe_2O_3 and Fe_3O_4, and that a coordination effect occurs between lithiation and iron extrusion, which shortens the steps of cyclic curves and improves the capacity significantly. These results are compared with experiments, in which α-Fe_2O_3 electrodes cycled in KOH solutions are tested by CV, XRD and ICP.

Key words: α-Fe2O3, Fe3O4, Aqueous secondary lithium batteries, Ni-Fe batteries