Investigation of Electrochemical Performance of Lithium-Sulfur Cell by Addition of Ti4O7 Conductive Metal Oxide

• Main Authors: YU,CHUN WEI, 余俊緯
• Other Authors: Tsai,Cho Jen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/08348557600263292995

碩士 === 國立清華大學 === 材料科學工程學系 === 104 === The lithium-sulfur batteries show significant potential for next-generation energy storage systems, due to its high specific capacity of 1675 mAh/g and theoretical energy density of 2600 Wh/kg are 3-5 times higher than conventional lithium ion battery. Furthermore, sulfur show advantages of low cost, environmental benign, and naturally abundant. The present work attempted to use Ti4O7 conductive metal oxide as an additive in the cathode to increase cycling performance owning to its high electric conductivity and chemical binding of soluble polysulfides. At the first part, the Ti4O7 was introduced to pure sulfur system through slurry mixing process. The results showed that the addition of 37.5 % to 50 % Ti4O7 could improve cycle life and capacity retention. From EIS measurement, we found that the charge transfer resistance was significantly reduced by addition of appropriate amount of Ti4O7. At the second part, the Ti4O7 was introduced to Graphene-S composite system through slurry mixing process. The results showed that the addition of 25 % to 50 % Ti4O7 could reduce charge transfer resistance and improve the capacity performance and cycle life. In addition, using Graphene-S composite as active material could lead to better sulfur utilization than pure sulfur system. At the third part, the Ti4O7 and conductive carbon black Super P were coated on the commercial polypropylene separator by doctor blade method. The functional coating layer has been investigated to improve the electrochemical performance of lithium-sulfur battery, and served as an upper current collector to facilitate electron transport and a conductive network for trapping and depositing dissolved polysulfides.