尖晶石相LiMn2O4電極與碳酸乙烯酯/碳酸二乙酯電解液間生成界面之研究

Studies on the SEI Formed between Spinel LiMn2O4 and EC/DEC Electrolyte

顏志榮(Chih-jung Yen)

指導教授 ： 吳溪煌

大同大學/工程學院/材料工程學系所/碩士(2006年)

摘要

以靜電噴塗沉積法(ESD)在白金板上沉積含Li、Mn離子之前驅物。經由不同溫度和持溫時間來進行熱處理製備尖晶石相的LiMn2O4正極，分別以ICP、XRD和SEM來測定電極的元素組成、結晶結構及表面型態。經由電容量測定來比較經不同熱處理條件所得正極之電化學特性。此種電極因不含任何黏結劑和助導劑，有助於固態電極-電解質層間之界面(SEI)的研究。在本研究中，以FTIR來分析形成SEI的官能基來推測生成界面化合物。雖然經由Hard X-ray分析並未在電極觀察到值得注意的變化，但由FTIR之觀察分析發現電解液與LiMn2O4電極間未經充電即有界面層生成。在首次充放電過程中，電池充電至4.1V以上時，可發現碳酸鋰(Li2CO3)界面層消失。而當放電至3.7V時，可發現有碳酸鋰(Li2CO3)和含(－(CO)OO(CO)－)官能基之介面層生成。且在隨後的充放電過程中，碳酸鋰(Li2CO3)和(－(CO)OO(CO)－)官能基會不斷重覆地於充電至4.1V消失和放電至3.7V時出現。

關鍵字

固態電解質界面 ； 鋰錳氧化物 ； 靜電噴塗沉積

並列摘要

Spinel LiMn2O4 was prepared via electrostatic spray deposition (ESD) method and followed by heat-treatment at various temperatures for various durations. The compositions, crystalline and morphology of the electrodes were investigated with ICP, XRD and SEM. The electrochemical properties of thus prepared electrodes were studied by capacity retention studies. These kind of electrode do not contain any binder or conductive. They are good for solid-electrolyte interface (SEI) studies. In this study, FTIR was used to investigate the SEI formed. It is found that Li2CO3 forms on the spinel electrode before cycling. However, no significant change on the electrode film was found by the image obtained by hard X-ray. The Li2CO3 disappeared as the coin cell was charged to 4.1 V. Compounds containing Li2CO3 and (－(CO)OO(CO)－) functional group appeared as the coin cell was discharged to 3.7 V. After that, Compounds containing Li2CO3 and (－(CO)OO(CO)－) functional group appeared/disappeared periodically as the cells discharged/charged to 3.7 V and 4.1 V, respectively.

並列關鍵字

LiMn2O4 ； SEI

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