PNNL

Abstract

Lithium-sulfur (Li-S) battery is a promising technology for use in large-scale energy storage and electric vehicles due to its high theoretical energy density and low cost. Reducing the sulfur cathode porosity has been identified recently as a viable strategy for improving cell practical energy density and minimizing pore-filling electrolytes to extend cell life. Direct use of a low-porosity cathode for Li-S battery results in poor electrode wetting and, thus, nonuniform electrode reactions. To mitigate the low-porosity electrode drawbacks and find strategies to address its limitation, multiscale modeling was performed by integrating pore-scale electrode wetting into the electrochemical reactions for predicting Li-S cell discharge profiles. Electrode wetting pattern, electrolyte distribution, and their impacts on sulfur reactions with different electrode architectures were simulated through a three-dimensional pore-scale electrode model and a one-dimensional device-scale model. The modeling results indicate low tortuosity, and large channel pores are critical to enhancing electrode wetting, species diffusion, and it has been suggested that increasing secondary particle size in the electrode could promote electrolyte wettability and sulfur reactivity. This study provides new insights into the materials and electrode design for low-porosity electrodes, accelerating the development of practical high-energy Li-S batteries.