Sulfur Cathodes In Lithium-sulfur Batteries Research Articles

A polyethylene glycol-supported microporous carbon coating as a polysulfide trap for utilizing pure sulfur cathodes in lithium-sulfur batteries.

A composite separator with a thin-film polysulfide trap is developed for lithium-sulfur batteries. A polyethylene glycol-supported microporous carbon coating (MPC/PEG coating) on a Celgard separator suppresses polysulfide diffusion through its physical and chemical polysulfide-trapping capabilities. The MPC/PEG-coated separator thus facilitates the use of pure sulfur cathodes that generally suffer from poor cyclability and low electrochemical utilization.

Enhanced cyclability of sulfur cathodes in lithium-sulfur batteries with Na-alginate as a binder

Na-alginate as a binder in an aqueous solvent has been applied in the preparation of sulfur cathodes for lithium-sulfur batteries. Their electrochemical performances have been investigated by a charge-discharge cycle test and electrochemical impedance spectroscopy (EIS). The EIS tests indicated that the alginate sulfur cathode had lower resistance and better kinetic characteristics than those of the poly(vinylidene fluoride) (PVDF) sulfur cathode using PVDF as a binder in a N-methy-2-pyrrolidone (NMP) solvent. The charge-discharge tests showed that the discharge capacity and the capacity retention rate of Na-alginate sulfur cathode were 508 mAh·g−1 and 65.4% at the 50th cycle with a current density of 335 mA·g−1. Compared with PVDF sulfur cathode, the alginate sulfur cathode showed a remarkably better cycle performance. These results show that the alginate binder has promising potential for lithium-sulfur battery applications.

Discharge Process of the Sulfur Cathode with a Gelatin Binder

Gelatin, a natural biologic macromolecule, was successfully used as a new binder in place of poly (ethylene oxide) (PEO) in the fabrication of sulfur cathode in lithium-sulfur batteries. The change of a gelatin binder sulfur cathode in the discharge-charge process was investigated by X-ray diffraction and differential scanning calorimetry analysis, and the results were compared with those of the sulfur cathode using PEO as a binder. Our results indicated that the gelatin binder could enhance the redox reversibility of sulfur cathode by slowing down the reducing reaction of elemental sulfur during the discharging process and reforming after the charging process.