Dielectric Barrier Discharge (DBD) Plasma Coating of Sulfur for Mitigation of Capacity Fade in Lithium–Sulfur Batteries

Abstract

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.

Recent advances and perspectives in conductive-polymer-based composites as cathode materials for high-performance lithium–sulfur batteries

“…In comparison with LIBs, lithium-sulfur batteries (Li-S batteries) are considered one of the most promising electrochemical storage systems owing to their high theoretical specic energy density ($2600 W h kg À1 ). [22][23][24][25][26][27][28][29][30][31][32] Nevertheless, there still exist several challenges that hinder the further development of Li-S batteries, such as low conductivity (5 Â 10 À30 S cm À1 ), low utilization of the sulfur cathode, and the shuttle effect of lithium polysuldes (LiPSs). [33][34][35][36][37][38][39] To address these challenges, researchers have made considerable efforts through the modication of sulfur Wang Jing received her BSc degree from the Luoyang Institute of Science and Technology in 2019 and continues to pursue a Master's degree under the supervision of Prof. Wanhong Zhang and Prof. Yong Liu at the Henan University of Science and Technology.…”

“…In comparison with LIBs, lithium–sulfur batteries (Li–S batteries) are considered one of the most promising electrochemical storage systems owing to their high theoretical specific energy density (∼2600 W h kg −1 ). 22–32 Nevertheless, there still exist several challenges that hinder the further development of Li–S batteries, such as low conductivity (5 × 10 −30 S cm −1 ), low utilization of the sulfur cathode, and the shuttle effect of lithium polysulfides (LiPSs). 33–39…”

Impact of Different Conductive Polymers on the Performance of the Sulfur Positive Electrode in Li–S Batteries

“…These traditional conducting polymers are well-known for their simple preparation procedure, high polysulfide-absorbing capability, and high electrical conductivity. Especially, the use of such polymers as surface coatings clearly shows good potential in tackling the problems associated with sulfur positive electrodes. ,, In addition, π-conjugated structures and N-containing functional groups in the backbone of conducting polymers can be adopted as active sites or reactive groups to confine the sulfur species. Thus, these conducting polymers are the most studied coating materials for Li–S batteries. ,, …”

Ni@Ni3N Embedded on Three-Dimensional Carbon Nanosheets for High-Performance Lithium/Sodium–Sulfur Batteries

“…1−3 Unfortunately, the actual energy densities of these batteries are far from their theoretical values due to the slow redox kinetics of sulfur and the poor conductivity of elemental sulfur (S 8 ), as well as the severe dissolution of lithium polysulfides (LiPSs). 3−6 Great efforts have been made to resolve these problems by the physical/chemical confinement within electrodes, such as nonpolar carbon materials, 7−9 conductive polymer, 10 and polar inorganics (metal oxides/ sulfides/nitrides). 11−15 However, the weak affinity of nonpolar carbon materials and the limited adsorption ability of polar noncarbon materials for LiPSs make these strategies unable to meet the requirements of the long cycle process and high sulfur-loading electrode.…”

“…Lithium–sulfur (Li–S) batteries have been considered as the most promising next-generation batteries for electric vehicles and portable electronic devices because of their comprehensive advantages such as high energy density (theoretically 2600 Wh kg –1 ), high natural abundance, low cost, and environmental benignity. − Unfortunately, the actual energy densities of these batteries are far from their theoretical values due to the slow redox kinetics of sulfur and the poor conductivity of elemental sulfur (S 8 ), as well as the severe dissolution of lithium polysulfides (LiPSs). − Great efforts have been made to resolve these problems by the physical/chemical confinement within electrodes, such as nonpolar carbon materials, − conductive polymer, and polar inorganics (metal oxides/sulfides/nitrides). − However, the weak affinity of nonpolar carbon materials and the limited adsorption ability of polar noncarbon materials for LiPSs make these strategies unable to meet the requirements of the long cycle process and high sulfur-loading electrode. − The basic reason should be ascribed to the slow conversion of high concentration LiPSs for high sulfur loading, and the accumulation of LiPSs in the electrolyte leads to severe shuttling between two electrodes. − Moreover, the microstructural/geometric design of the host matrices plays an important role for Li-S batteries.…”