- 學位論文
鋰離子電池負極材料—軟碳之製備與研究
PREPARATION AND INVESTIGATION OF SOFT CARBON ANODE MATERIALS FOR LITHIUM ION BATTERIES
摘要
介相瀝青碳經由在空氣中500oC煆燒1小時，再進行700到1100oC的碳化處理，在氮氣氣氛下持溫1小時。透過X光繞射儀、元素分析儀及拉曼光譜分析儀等儀器，對所得到的介相瀝青碳粉末進行結構以及組成的分析，並測試其充放電之電化學特性。結果顯示，有序結構在溫度高於800oC時會隨著熱處理溫度增加而增加；合成之粉末中以經700oC熱處理製備的粉末具有最高的電容量，但是也呈現最明顯的電容量衰退現象；而1100oC製備的粉末電容量為所有樣品中最低的，但循環穩定性較高。與商業用的碳材料相比較，具有較好的高速充放電能力以及較高的第一圈不可逆電容量。為了改善第一圈不可逆電容量的損失，利用表面修飾的方法將不同濃度的焦煤瀝青包覆在碳粉表面，以900oC熱處理後有些許的改善。
並列摘要
Mesophase pitch carbons were prepared via calcination at 500oC and heat-treatment at temperatures between 700 and 1100oC with pitch as precursor. The structure, composition, and electrochemical properties of the prepared carbons were investigated with XRD, elemental analysis, and capacity retention study. It was found that the ordered structure increases with increasing heat-treatment temperature for samples prepared at temperatures higher than 800oC. The sample prepared at 700oC exhibited the highest reversible capacity among these prepared samples, however, it showed significant capacity fading after cycling. The charge/discharge curves of these samples are similar to those of graphite. By comparing the commercial carbonaceous materials, the rate capability and the irreversible capacity of initial cycle are higher than those of the commercial materials. In order to lower the initial irreversible capacity loss, surface modification was done by coating different concentration of coal-tar pitch. The initial irreversible capacity was decreased slightly by heat at 900oC.