Lithium-Sulfur Batteries

2 Sulfur Cathodes

Holger Althues Susanne Dörfler Sören Thieme Patrick Strubel and Stefan Kaskel

Fraunhofer‐Institut für Werkstoff‐und Strahltechnik IWS, Winterbergstraße 28, 01277, Dresden, Germany

2.1 Cathode Design Criteria

2.1.1 Overview of Cathode Components and Composition

The active material layer of a Li–S cathode consists of elemental sulfur, carbon materials, and binders. Typically, aqueous slurries of the components are coated onto a current collector in a reel‐to‐reel coating process, and the solvent is removed by drying to leave active components. Dry layer thickness may be in the range of 20–200 µm. Similar to Li‐ion battery cathodes, thin aluminum foils (thickness: 10–20 µm) are used as current collector and as substrate of the active material layer. Primer coatings, based on carbon‐filled polymer films, can be applied on the current collector prior to coating the active materials in order to enhance adhesion or decrease interface resistance to the active layer (Figure 2.1).

Figure 2.1 (a) Scheme of a Li–S cell stack and its components. (b) Scheme of a multilayer Li–S pouch cell.

Due to the low electrical conductivity of sulfur and the related discharge products (lithium(poly‐)sulfide(s)), the conductive carbon materials are key components within the active cathode layer. Carbons are typically applied in fractions of 20–50 wt% within the cathode ...