探討以溶膠凝膠法結合固態燒結法合成的陰極材料Li2CoPO4F之電性表現

Investigation on electrochemical performance of Li2CoPO4F cathode material produced by sol-gel method combining with solid-state method

胡子怡(Hu, Zi Yi)

指導教授 ： 蔡哲正

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00519

摘要

高電壓的陰極材料Li2CoPO4F，具有高理論電容量可達287 mAh/g。本實驗先以溶膠凝膠法合成出LiCoPO4，再加入LiF並以固態燒結法合成出Li2CoPO4F，主要探討改變LiCoPO4的製程條件和Li2CoPO4F的燒結條件時，對Li2CoPO4F電性表現的影響。
第一部份為改變LiCoPO4的製程條件，分成四系列：不同化學配比之LiCoPO4；不同鐵離子取代量之LiCoPO4；不同預燒溫度之LiCoPO4；不同預燒溫度之LiCoPO4進行木寡糖包覆與否。第二部份為改變Li2CoPO4F的燒結條件，分成兩系列：不同燒結溫度之Li2CoPO4F；不同燒結時間之Li2CoPO4F。
在本實驗各製程參數的Li2CoPO4F當中，首圈放電電容量最高的是－預燒溫度為420 oC的LiCoPO4所製得的Li2CoPO4F，可達140 mAh/g；而前15圈平均放電電容量最高的是－預燒溫度為500 oC的LiCoPO4進行糖包覆所製得的Li2CoPO4F，約為89.5 mAh/g。本實驗也得到Li2CoPO4F燒結條件的結論：700 oC為最佳的燒結溫度，且在700 oC的燒結溫度下，燒結時間在1.5 ~ 12小時之間變動時，結果差異不大。

關鍵字

鋰離子電池 ； 高電壓陰極材料 ； 氟磷酸鈷二鋰

並列摘要

Li2CoPO4F, a high-voltage cathode material which has high theoretical capacity of 287 mAh/g. This study used sol-gel method to synthesize LiCoPO4 and then used solid-state method to synthesize Li2CoPO4F with LiF, controlling the synthetical conditions of LiCoPO4 and Li2CoPO4F to explore the effects on electrochemical performance. First, we altered some experimental parameters of synthesizing LiCoPO4 in four series, including matrix composition, iron ion replacement, sintering temperature and whether coating xylooligosaccharide or not. Second, we altered some experimental parameters of synthesizing Li2CoPO4F in two series, including sintering temperature and time.
In this study, among the first cycle discharge capacity of all, Li2CoPO4F made by 420 oC sintering LiCoPO4 has the highest value of 140 mAh/g；among the average discharge capacity of 1 ~ 15 cycles of all, Li2CoPO4F made by 500 oC sintering xylooligosaccharide-coated LiCoPO4 has the highest value of 89.5 mAh/g. The experimental results also indicate that 700 oC is the best sintering temperature, and the consequences are almost the same when sintering time varies in 1.5 ~ 12 hours at 700 oC.

並列關鍵字

Lithium ion battery ； High-voltage cathode material ； Cobalt fluorophosphate

參考文獻

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