Unlocking Failure Mechanisms and Improvement of Practical Li–S Pouch Cells through In Operando Pressure Study. Issue 7 (7th December 2021)

• Record Type: Journal Article
• Authors: Chinnam, Parameswara R.; Xu, Leidong; Cai, Lu; Cordes, Nikolaus L.; Kim, Sangwook; Efaw, Corey M.; Murray, Daniel J.; Dufek, Eric J.; Xu, Hongyi; Li, Bin
• Is Part Of: Advanced energy materials. Volume 12:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-07
• Subjects: failure mechanisms -- lithium–sulfur batteries -- operando -- pouch cells -- pressure -- wettability; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202103048
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: For lithium–sulfur battery commercialization, research at a pouch cell level is essential, as some problems that can be ignored or deemed minimal at a smaller level can have a greater effect on the performance of the larger pouch cell. Herein, the failure mechanisms of Li–S pouch cells are deeply investigated via in operando pressure analysis. It is found that highly porous structures of cathodes/separators and slow electrolyte diffusion through cathodes/separators can both lead to poor initial wetting. Additionally, the Li‐metal anode dominates the thickness variation of the whole pouch cell, which is verified by in situ measured pressure variation. Consequently, a real‐time approach that combines normalized pressure with differential pressure analysis is proposed and validated to diagnose the morphology evolution of the Li‐metal anode. Moreover, applied pressure and porosity/tortuosity ratio of the cathode are both identified as independent factors that influence anode performance. In addition to stabilizing anodes, high pressure is proven to improve the cathode connectivity and avoid cathode cracking over cycling, which improves the possibility of developing cathodes with high sulfur mass loading. This work provides insights into Li–S pouch cell design (e.g., cathode and separator) and highlights pathways to improve cell capacity and cycling performance with applied and monitored pressure. Abstract : Through an operando pressure study on a practical Li–S pouch cell, the role of pressure and the failure mechanisms due to poor wetting are revealed, and the Li metal anode degradation can be diagnosed in real time. These results shed light on the rational design of high‐energy density Li–S batteries and materials development at the pouch cell level.