Understanding of Failure Mechanism of High Energy Lithium-Sulfur Pouch Cells

Abstract

Lithium sulfur (Li-S) battery is a promising next generation energy storage technology for vehicle electrification or large scale energy storage due to the high theoretical energy, low cost, and environmental friendliness of sulfur. 1 However, deployment of Li-S batteries in practical applications has been hindered by the low practical energy and limited cycle life. Extensive researches in Li-S batteries have been performed, and significant advances have been demonstrated in material development and fundamental understandings of the reaction mechanism. 2, 3 However, most of the previous studies are based on thin film sulfur electrodes, excess amount of electrolyte, or small size coin cell configuration. It has been reported that sulfur utilization and cycle life are both affected if using electrodes with elevated sulfur loading and under conditions of lean amount of electrolyte. 4 This indicates scientific gaps existing between the high loading electrodes and the reported thin film counterparts. The new understandings and knowledge linking the “theoretical” and “practical” are essential for the further maturing of the Li-S battery technology. In an attempt to fill such scientific gaps, high energy Li-S pouch cells were designed and fabricated in our research by using high loading electrodes and lean electrolyte. Practically high energy of 372 Wh kg-1 has been demonstrated in the Li-S pouch cells although cycle life is still limited. Systematic understanding of cell failure mechanism under practical conditions was carried out by using advanced characterization techniques. Electrolyte depletion and non-uniformity of electrochemical reactions of both cathode and anode were identified as dominant factors of cell capacity decay and internal short-circuit. Detailed postmortem analysis of the cycled Li-S pouch cell and failure mechanism understanding will be presented and discussed at the meeting. References A. Manthiram, Y. Z. Fu, S. H. Chung, C. X. Zu and Y. S. Su, Chem. Rev., 2014, 114, 11751-11787.D. Aurbach, E. Pollak, R. Elazari, G. Salitra, C. S. Kelley and J. Affinito, J. Electrochem. Soc., 2009, 156, A694-A702.X. L. Ji, K. T. Lee and L. F. Nazar, Nat. Mater., 2009, 8, 500-506.D. P. Lv, J. M. Zheng, Q. Y. Li, X. Xie, S. Ferrara, Z. M. Nie, L. B. Mehdi, N. D. Browning, J. G. Zhang, G. L. Graff, J. Liu and J. Xiao, Adv. Energy Mater., 2015, 5, 8.