Effect of Carbon Morphology and Slurry Formulation in Sulfur Cathode for Li-S Batteries

The performance of Lithium-Sulfur (Li-S) batteries is significantly influenced by material selection and manufacturing processes, with conductive carbon and slurry formulation playing crucial roles. In this study, the impact of carbon morphology and solvent/solid ratio in slurry preparation on microstructure and electrochemical performance of sulfur cathodes was investigated. Various carbon structures, such as nanotubes, sheets, and particles, were explored, and the solvent volume was adjusted to assess their effects on electrode architecture and electrochemical performance. Our findings demonstrate that the binder dissolution process and consequent electrode architecture and performance are highly influenced by both the carbon structure and slurry solvent volume. Furthermore, it was observed that, contrary to common assumption, advanced carbon structures are not necessary for enhanced capacity and durability of Li-S cathodes. Accordingly, the best cycling durability was achieved by optimizing the slurry with 300 mu L/mgPVDF of NMP solvent and using Ketjen black as the conductive carbon, resulting in an initial capacity of 1029 mAh gS-1, with a retention of 830 mAh gS-1 after 500 cycles. These results, obtained at a high areal loading of 4.5 mgS cm-2, demonstrate the commercial potential of the proposed electrode formulation and processing method without reliance on advanced materials or techniques.