How to Model the Cathode Area in Lithium‐Sulfur Batteries?

Abstract

In this study, a 1‐D electrochemical model was employed to predict the effect of key design parameters, such as carbon‐to‐sulfur (C/S) ratio, electrolyte‐to‐sulfur (E/S) ratio, and sulfur loading on the discharge capacity and voltage profile of a lithium‐sulfur (Li−S) battery. Herein, a novel definition for the electrochemically active area is proposed based on the weight fraction of carbon and a reference porosity in the cathode. The experimental trends of the discharge behavior of a Li−S cell were captured by the model regarding the change in key design parameters. Results were given in comparison with the predictions of two other models that use different active area definitions, and it was concluded that a sensible representation of the electrochemically active area is critical for modeling the effect of cell design on the discharge performance of a Li−S battery.

Influence of Sulfur Loading on Lithium‐Sulfur Battery Performance for Different Cathode Carbon Types

“…Recently, modeling and characterization of the key parameters, such as the electrolyte-to-sulfur (E/S) ratio and the carbon-to-sulfur (C/S) ratio, have been reported in the literature. [3][4][5][6][7][8] Sulfur loading is another essential design parameter in the cathode, which is highly determinative of the LiÀ S performance; the energy density of LiÀ S batteries is expected to excel at high levels of sulfur loadings. [9] On the other hand, low S loadings and high E/S ratios are typically desired for LiÀ S batteries to have high discharge capacities and prolonged cycle life (S loadings < 2 mg cm À 2 and E/S ratios > 35 mL g À 1 are typical in the literature [10][11][12] ).…”

“…In Li−S batteries, intelligent cathode design is a robust approach to obtaining high performance. Recently, modeling and characterization of the key parameters, such as the electrolyte‐to‐sulfur (E/S) ratio and the carbon‐to‐sulfur (C/S) ratio, have been reported in the literature [3–8] . Sulfur loading is another essential design parameter in the cathode, which is highly determinative of the Li−S performance; the energy density of Li−S batteries is expected to excel at high levels of sulfur loadings [9] .…”