Predicting cell failure and performance decline in lithium-sulfur batteries using distribution of relaxation times analysis

While lithium-sulfur (Li-S) batteries are a promising next-generation technology, their complex chemistry means they can degrade and fail via numerous mechanisms. To minimize or overcome these modes of failure, we must develop tools that can differentiate between chemical processes in the operating cell, reveal their effects on cell health, and monitor cells throughout their lifetimes. In this study we undertake a comprehensive investigation of the failure modes exhibited by Li-S cells, using the distribution of relaxation times (DRT) method. By evaluating the contribution of various electrochemical processes to overall cell resistance, we establish meaningful correlations between performance degradation and specific electrochemical/materials phenomena. Notably, the DRT profiles reveal that the solid-electrolyte interphase resistance can serve as an early indicator of impending cell failure. The methodologies and findings presented in this study hold substantial implications for the advancement of on-board diagnostics tailored for Li-S batteries and other cell chemistries.