Polyaniline-modified cetyltrimethylammonium bromide-graphene oxide-sulfur nanocomposites with enhanced performance for lithium-sulfur batteries

Abstract

Conductive polymer coatings can boost the power storage capacity of lithium-sulfur batteries. We report here on the design and preparation-by combining a facile and green chemical deposition method with an oxidative polymerization approach-of polyaniline (PANI)-modified cetyltrimethylammonium bromide (CTAB)-graphene oxide (GO)-sulfur (S) nanocomposites with significantly enhanced performance in lithium-sulfur batteries. Such conductive polymer modified CTAB-GO-S nanocomposites as sulfur cathode materials can deliver high specific discharge capacities and long-term cycling performance, i.e., ∼970 mAh·g−1 at 0.2 C and ∼715 mAh·g−1 after 300 cycles, ∼820 mAh·g−1 at 0.5 C and ∼670 mAh·g−1 after 500 cycles, ∼770 mAh·g−1 at 1 C and ∼570 mAh·g−1 after 500 cycles. The capacity decay was as low as 0.036% per cycle at 0.5 C, and 0.051% per cycle at 1 C. Under the same condition, batteries using PANI-modified CTAB-GO-S as cathodes exhibited higher specific capacity and higher average coulombic efficiency compared with CTAB-decorated GO-S and GO-S nanocomposites. The improved performance can be attributed to the lower charge transfer resistance and the alleviated dissolution of polysulfides in the PANImodified CTAB-GO-S cathodes.