Evaluation of Procedures for the Synthesis of LiCoO2 Cathode Materials and Improvements Thereby

• Main Authors: Zai-Xian Weng, 翁再賢
• Other Authors: George Ting-Kuo Fey
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/52812274637101084825

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 90 === 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.