LiCoO2陰極材料重要製程評估與改質研究; Evaluation of Procedures for the Synthesis of LiCoO2 Cathode Materials and Improvements Thereby

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Title:	LiCoO2陰極材料重要製程評估與改質研究;Evaluation of Procedures for the Synthesis of LiCoO2 Cathode Materials and Improvements Thereby
Authors:	翁再賢;Zai-Xian Weng
Contributors:	化學工程與材料工程研究所
Keywords:	鋰鈷氧化物;電化學特性;循環伏安法;陰極材料;鋰電池;Electrochemical Properties;Cathode Materials;LiCoO2;Lithium Battery;Cyclic Voltammetry
Date:	2002-05-06
Issue Date:	2009-09-21 12:20:58 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	初步以文獻中選出具代表性的十種製程—P-1至P-10（P.42，表06）—合成LiCoO2產物，於相同條件下作電池循環測試後，發現初始可逆電容量以固態法P-1的154mAh/g為最高；若以電容量維持率80％為標準來比較各製程材料之循環壽命，則以溶液法P-3的81次為最佳。接著，將10種製程分別以其原料成本、耗電成本、長循環測試以及初次可逆電容量等作為評估條件，經過權重分析計算後，結果以P-3有最高的權重分析值，其次P-5及P-1，結果顯示P-3為十種製程當中兼具電池性能高以及經濟成本低兩大優點的製程。接著吾人針對P-3製程作合成條件之最適化研究，改變其煆燒溫度、煆燒時間、鋰計量數以及煆燒氣氛等變因後發現，當煆燒溫度800℃、煆燒時間10小時及鋰計量數為1時，於空氣下煆燒其所合成出來的產物擁有最佳的電池性能，其初始可逆電容量為154 mAh/g，經過30次循環後，可逆電容量維持率為92％。為了增加循環穩定性，吾人分別以鎂取代部分鈷及摻雜微量鍶離子兩種變因，研究其對材料電容量及循環穩定性的影響。結果發現以LiMg0.025Co0.975O2材料的電池性能最佳，初次可逆電容量153mAh/g，循環壽命為110次，顯示以鎂取代部分鈷對材料之循環穩定性有相當大的助益。另外，於材料中摻雜微量鍶離子後，發現產物會由於鍶離子的加入，而使其初始可逆電容量降低，並且降低了其循環穩定性，並未達到預期摻雜微量鍶離子之效果。 In this study, ten typical processes – P-1 to P-10 – were chosen for the synthesis of LiCoO2. Among all the processes, P-1 resulted in a material with the highest first-cycle discharge capacity (154 mAh/g). However, P-3 yielded products with the lowest capacity fade (charge retention at the end of 81 cycles was 80%). Based on the material cost, cyclability and the first-cycle discharge capacity, P-3 was adjudged the best method, followed by P-5 and P-1. Having determined that P-3 was the best synthetic route, we proceeded to examine the best conditions for the P-3 process. A calcination temperature of 800℃ and heat treatment duration of 10 hours in air were found to be the optimal conditions. A product obtained under these conditions showed a first-cycle discharge capacity of 154 mAh/g, retaining 92% of the capacity after 30 cycles. The synthetic procedure P-3 was extended to obtain the Mg-doped composition, LiMg0.025Co0.975O2. The material gave a first-cycle discharge capacity of 153 mAh/g. However, it could sustain 110 cycles before 20% of its capacity was lost. Similarly, a Sr-doped LiCoO2 composition was also studied. Doping with Sr was detrimental not only to the deliverable capacity, but also reduced cycling stability.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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