Sulfur particles with a conductive polymer coating of poly(3,4ethylene dioxythiophene) "PEDOT" were prepared by dielectric barrier discharge (DBD) plasma technology under atmospheric conditions (low temperature, ambient pressure). We report a solvent-free, low-cost, low-energyconsumption, safe, and low-risk process to make the material development and production compatible for sustainable technologies. Different coating protocols were developed to produce PEDOT-coated sulfur powders with electrical conductivity in the range of 10 −8 −10 −5 S/cm. The raw sulfur powder (used as the reference) and (low-, optimum-, high-) PEDOT-coated sulfur powders were used to assemble lithium−sulfur (Li−S) cells with a high sulfur loading of ∼4.5 mg/cm 2 . Long-term galvanostatic cycling at C/10 for 100 cycles showed that the capacity fade was mitigated by ∼30% for the cells containing the optimum-PEDOT-coated sulfur in comparison to the reference Li−S cells with raw sulfur. Rate capability, cyclic voltammetry, and electrochemical impedance analyzes confirmed the improved behavior of the PEDOT-coated sulfur as an active material for lithium−sulfur batteries. The Li−S cells containing optimum-PEDOT-coated sulfur showed the highest reproducibility of their electrochemical properties. A wide variety of bulk and surface characterization methods including conductivity analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and NMR spectroscopy were used to explain the chemical features and the superior behavior of Li−S cells using the optimum-PEDOT-coated sulfur material. Moreover, postmortem [SEM and Brunauer−Emmett−Teller (BET)] analyzes of uncoated and coated samples allowed us to exclude any significant effect at the electrode scale even after 70 cycles.

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Sulfur particles were coated with conductive polymer layers by dielectric barrier discharge (DBD) plasma technology under atmospheric conditions (ambient pressure and low temperature). The DBD plasma process is a dry and sustainable (solvent-free, limited energy consumption) technique compatible with upscaling. Different conductive coated sulfur materials were produced and labeled as “PEDOT-S” [poly­(3,4-ethylene dioxythiophene-sulfur)], “PANI-S” (polyaniline-sulfur), “PTs-S” (polythiophene-sulfur), and “PPy-S” (polypyrrole-sulfur). The corresponding electrical conductivities were measured at 10–5, 10–6, 10–7, and 10–8 S/cm, respectively. The role of the conductive coating is to enhance the electrochemical performance of Li–S cells by improving the electronic conductivity of the sulfur particles and preventing the well-known polysulfide shuttle phenomenon. A vast range of characterization methods including conductivity analysis, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and carbon-13 NMR (nuclear magnetic resonance spectroscopy) were used to assess the chemical characteristics using the different conductive polymer-coated sulfur materials. In the coated sulfur samples, fragmentation of aromatic rings was observed, 88% for the PTs-S and 42% for the PEDOT-S, while it is very limited for the PANI-S. Such a phenomenon has never been reported in the literature. The uncoated and coated sulfur powders were used (as active material) in positive electrodes of Li–S cells with a relatively high sulfur loading of ∼4.5 mg/cm2 using LiPAA (lithium polyacrylate) as an (aqueous) binder. Long-term galvanostatic cycling at C/10 and multi-C-rate tests showed the capacity fade and rate capability losses to be highly mitigated for cells containing conductive polymer-coated sulfur in comparison to cells using the uncoated sulfur. Kinetic investigations by cyclic voltammetry and electrochemical impedance spectroscopy analyses undoubtedly confirm improved electron and Li-ion transport within the electrodes containing conductive polymer-coated sulfur. The electrochemical performance can be ranked as PEDOT-S > PANI-S > PTs-S > PPy-S > raw sulfur.