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

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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