- 學位論文
以磷酸三甲酯和馬來醯亞胺改善鋰離子電池電解液特性之比較研究
Comparison and study of Property of lithium battery electrolyte with Trimethyl phosphate and Maleimide
摘要
本研究透過雙成分添加劑欲改善電解液的安全性與電化學性能，使用磷酸三甲酯和馬來醯亞胺添加入電解液中做為高安全鋰離子電池，為了使電池能夠具有高性能的難燃性仍可兼顧電池的循環壽命，因此同時加入兩種添加劑，另外一個主要目標在於優化鋰離子的循環壽命。電解液配置是用1.1M的LiPF6 ，碳酸丙烯：碳酸乙烯：碳酸二乙酯(體積比2:3:5)，包含磷酸三甲酯和馬來醯亞胺添加劑，用以促進形成新的鈍化膜。此雙成分添加劑希望具有下列特性:(1)具雜環類化合物及高苯環密度，因而有良好的熱安定性；(2) 馬來醯亞胺單體末端具有高反應性的不飽和雙鍵，可以改善應用在一般材料和電子材料上； (3)含磷官能基遇熱可形成的含磷自由基能夠捕獲和碳產生鏈鎖反應的氫自由基，阻止爆炸燃燒時發生的機率。 (4)混合後的含磷類馬來醯亞胺添加劑具有良好的耐熱性、溶解性、 較低的黏度、較好的成膜性。實驗結果顯示，當磷酸三甲酯加入電解液中時，由於具有含磷官能基的存在，能夠降低熱失控時鏈鎖反應的發生機會，達到電解液難燃的效果。但是添加量需要到10%以上，在電池活化後所形成的SEI膜會造成電池性能衰退，當添加馬來醯亞胺後，透過雜環上優良的末端反應官能基修飾陽極碳上的SEI膜，不但能夠在較低的添加比例下顯示出較好的難燃性以外，並且電化學性質也明顯改善，除了電容量的提升以外，循環壽命的可逆電容量也隨著添加比例增加而上升，此兩種添加劑混摻的添加，對於幫助改善電池的性能是非常重要的，值得深入探討學習。
並列摘要
This study is to improve the safety and electrochemical properties of electrolyte with binary additives, trimethyl phosphate and maleimide. The binary additives can make the lithium ion batteries with high flame resistance and high cycle life ability. They can also prefer to extend the cycle life of lithium. An initial electrolyte system contains 1.1M LiPF6, propylene carbonate (PC), ethylene carbonate (EC), diethylene carbonate (DEC), and then adds the TMP, and MI additives resulted in a novel solid electrolyte interface (SEI) formation. The ratio of PC:EC:DEC is 2:3:5 in volume. The characteristic of these binary additives is expected as follows: 1.Good thermal stability due to the heterocyclic compounds and high density of benzene. 2.High reactivity of the unsaturated double bonds at the end of Maleimide monomers, can improve the application in general and electronic materials . 3.Prevent the probability of explosion when the phosphate groups are heated, they form phosphate free radicals resulted in carbon-chain reaction and produced hydrogen free radicals. 4.Good heat tolerance, solubility, film-forming ability, and lower viscosity after mixing MI additives with phosphate.The results show when adding more than 10% of TMP to electrolyte, it can reduce the probability of unstable chain reaction to obtain the nonflammable electrolyte effect due to the presence of phosphate group. SEI film can reduce battery performance after activation. Therefore, Maleimide can modify the SEI film on the anode carbon through fine functional groups on heterocyclic compounds. It not only shows a better flame resistance at a lower usage but also improves better electrochemical properties. Besides the electric capacity can be increased, the life cycle of reversible electric capacity can also be improved by increasing the usage of additives. The mix of these two additives is very important to improve the battery performance. Further research work is worth to do on this study.