Sulfur-decorated polyaniline-nanotube composites as cathode materials for lithium metal batteries

Various composites of polyaniline (PANI) and polyanisidine (PAnis) with multi-walled carbon nanotubes (MWCNTs) and sulfur have been prepared using a simple one-pot and single-step strategy based on in situ chemical polymerization of aniline monomers in the presence of sulfur, MWCNTs and ammonium persulfate. The resulting composites contained 0 % to ∼25 % sulfur by weight and were characterized with nitrogen adsorption-desorption isotherms, thermogravimetric analysis, scanning electron microscopy with elemental mapping. Since most of the results for PANI/sulfur composites were reported for sulfur-rich systems (>40 %), the aim of this work was to investigate, for the first time, the obtained composites with low sulfur content as cathodes for metal-ion batteries. The utilization of both nanotubes and sulfur is beneficial for PANI-based electrode materials and enables better cycling stability, redox process reversibility and higher specific capacity. As a result, PANI/MWCNTs/S composite demonstrated a specific discharge capacity of 165 mAh g⁻¹ at the current density of 100 mA g⁻¹ and an average discharge potential of 2.4 V. Furthermore, we have shown the feasibility of the fabrication of potassium batteries using PANI- or PAnis-based composite cathodes, which paves a way to the development of inexpensive and scalable post-lithium battery technology.