Preparation and electrochemical properties of sulfur-polypyrrole composite cathodes for electric vehicle applications

The dissolution of polysulfides from the cathode remains a key roadblock in the advancement of Li-S batteries. In this work, we have explored the possibility of using sulfur-polypyrrole composite cathodes for suppressing polysulfide dissolution. Tubular polypyrrole was synthesized by a self-degraded template method and the effect of the amount of oxidant (FeCl₃) on the electrochemical performance of sulfur-polypyrrole composite cathodes was studied. To achieve the performance suitable for electric vehicle applications, the sulfur loading of the electrode was maintained at 4.5 mg cm^-2. The sulfur-polypyrrole composite cathode showed a better performance compared to bare sulfur, despite the high sulfur loading and thickness. Further, the amount of polypyrrole synthesized increased with an increase in the oxidant ratio. However, the addition of an excess amount of oxidant beyond 12.6 mmol affected the shape of polypyrrole and resulted in spherical clusters, which caused deterioration in the electrochemical performance.