Abstract: A method for modifying an electrode comprising an alkali metal is disclosed, the method comprising casting a salt solution comprising at least one salt comprising an alkaline ion and a solvent on the electrode; casting a fluoropolymer solution comprising at least one fluoropolymer and a solvent on the electrode; and drying the electrode. Also disclosed is an electrode comprising an alkali metal at least partly covered by a solid electrolyte interphase, said solid electrolyte interphase having atomic ratios of carbon, fluorine and sulfur atoms of 1 C:0.15 to 0.80 F:0.02 to 0.30 S.

Abstract: An electrochemical cell comprising: an anode comprising lithium or sodium metal, or lithium or sodium metal alloy; an ionically conductive cathode comprising an electroactive sulfur material; and a liquid electrolyte comprising at least one lithium salt or at least one sodium salt, wherein the polysulfide solubility of the electrolyte is less than 500 mM.