α-Fe_2O_3在LiOH水溶液中的锂化行为  

Lithistion Behavior of α-Fe_2O_3 in LiOH Electrolyte Solution

作　　者：李明[1] 杨华铨[1] 

机构地区：[1]北京大学化学系,北京100871

出　　处：《物理化学学报》2000年第8期735-740,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金!(29673002)

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．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 electrochendcally 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.

关 键 词：水溶液锂离子电池 α-氧化铁 氢氧化锂 锂化反应 

分 类 号：O646[理学—物理化学]