o-LiMnO2和LiMn1-xMxO2 (M=Cr, Fe, Al, Mg)正極材料的製備及特性研究

Preparation and Characterization of o-LiMnO2 and LiMn1-xMxO2 Materials (M=Cr, Fe, Al, Mg)

蔡孟宏(Meng-hung Tsai)

指導教授 ： 吳溪煌

大同大學/工程學院/材料工程學系所/碩士(2007年)

摘要

以Pechini法合成o-LiMnO2及LiMn1-xMxO2(M = Fe, Cr, Al, Mg; x = 0.05, 0.10)粉末。使用ICP、XRD、SEM分析合成粉末之組成、結晶構造及表面形態，以循環伏安及循環充放電分析合成粉末之正極材料特性。發現微量摻雜Al、Fe之生成粉末仍為orthorhombic相，其充放電行為與o-LiMnO2類似；而微量摻雜Cr、Mg之粉末則分別生成含有少量orthorhombic相之monoclinic及tetragonal相。兩者之充放電曲線與o-LiMnO2不同，初循環充放電比電容量都不會隨循環圈數增加而增加，經30圈循環充放電也不見比電容量衰減現象，其中以摻雜Cr3+離子之粉末之效果更佳，合成之LiMn0.9Cr0.1O2粉末具180 mAh/g之可逆比電容量。

關鍵字

Pechini製備法 ； 摻雜效果 ； o-LiMnO2 ； 正極材料

並列摘要

o-LiMnO2 and LiMn1-xMxO2(M = Fe, Cr, Al, or Mg; x = 0.05, 0.10) were prepared by Pechini method. The effects of doping on the composition, the crystalline structure, morphology, and the electrochemical properties of the prepared powders were investigated with ICP, XRD, SEM, cycling voltammetry, and capacity retention study. Powders doped with Al3+ or Fe3+ remain orthorhombic, and show similar electrochemical performances as o-LiMnO2. However, samples doped with Cr3+ and Mg2+ manifested as monoclinic and tetragonal structured with orthorhombic as minor, respectively. They do not show increasing capacity during the initial cycles due to the transformation into spinel like structure as the cycling performance of o-LiMnO2. Furthermore, no capacity fade was observed after 30 cycles. Among the prepared samples, that the powders doped with Cr3+ exhibit the most promising cycling performance. LiMn0.9Cr0.1O2 show reversible discharge capacity of 180 mAh/g.

並列關鍵字

doping effect ； o-LiMnO2 ； cathode materials ； Pechini method

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