Modeling of the temporal evolution of polysulfide chains within the lithium-sulfur battery

The lithium-sulfur battery belongs to the group of promising technologies known as post lithium-ion batteries, due to its high specific capacity of 1672 Ahkg(-1), specific energy density of around 2600 Whkg(-1) and the expected low price. Due to low performance, capacity fading and low coulombic efficiency, the commercialization is slow. The complex mechanisms of precipitation and dissolution of the individual polysulfide chains are described in a mathematical model. The model is based on the Nernst-formulation (concentration dependence) and the Butler-Volmer-equation (reaction kinetics). In the mathematical model, the evolution as well as the appearance of the individual polysulfide chains are described as a function of the C-rate. In this model, the nucleation of the precipitating solid and the recrystallization are represented. Depending on the state of charge, the model predicts the precipitation/dissolution and the appearance of the individual polysulfide chains. A prototype lithium-sulfur pouch cell is experimentally investigated, and the yielded measurement results are related to the model. The mathematical description could be used as foundation for mechanical studies, as well as for control algorithms (battery-management-system) to monitor the individual cells.

Automated summary

The lithium-sulfur battery, a promising post lithium-ion battery technology, has attracted attention for its high specific capacity and low price. However, its commercialization progress is slow due to low performance, capacity fading, and low coulombic efficiency. In this study, a mathematical model is developed to describe the complex mechanisms of precipitation and dissolution of individual polysulfide chains. The model is validated by experimental measurements on a prototype lithium-sulfur pouch cell.