Impact of Solid Precipitate on the Morphology and Performance of Lithium-Sulfur Battery Cathodes

Kurzfassung

Lithium-sulfur (Li-S) batteries are a promising technology for next-generation energy storage. However, the performance of Li-S batteries is affected by the solid precipitate formation during charge and discharge, passivating active surfaces and changing cathode morphology. This can have negative impact on the properties and overall battery performance, preventing their usage in key applications, such as in e-aviation. Morphological changes in the microstructure, resulting from surface reactions, dissolution, and precipitation are difficult to characterise due to their complex interactions. Previous computational approaches used simplified physico-chemical models [1,3,4] or multi-scale approaches based on geometrical submodels of representative volume elements which feed into homogenized models on cell scale [5]. However, these approaches are limited in their accuracy and predictive usage, preventing the development of mitigation strategies. Thus, a more detailed and physically-based model is needed to understand these elusive phenomena. In this work, a simulation study was performed using a specifically designed lattice Boltzmann method (LBM), to better understand the impact of solid precipitate formation. The driving dynamics and phenomena in Li-S batteries are mesoscopic in nature, for which the LBM has shown to outperform conventional methods at the pore scale due to its efficient computational parallelization and ability to capture complex physics. Our model was used to perform simulations of three-dimensional porous Li-S battery cathodes, resolved at a sub-micron level. The resulting simulations capture nucleation and growth of precipitates in high detail, providing valuable insight into the phenomena of pore clogging and surface passivation. These findings on the microscale can be used to guide design decisions of future material, electrode, and cell concepts for Li-S batteries.