Provided is a method of producing a rechargeable alkali metal-sulfur cell, comprising: (a) providing an anode layer; (b) providing particulates comprising primary particles of a sulfur-containing material encapsulated or embraced by a thin layer of a conductive sulfonated elastomer composite, wherein the conductive sulfonated elastomer composite comprises from 0% to 50% by weight of a conductive reinforcement material dispersed in a sulfonated elastomeric matrix material, and the conductive sulfonated elastomer composite has a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 500%, a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm, and an electrical conductivity from 10−7 S/cm to 100 S/cm; (c) forming the particulates, a resin binder, and an optional conductive additive into a cathode layer; and (d) combining the anode layer, the cathode layer, an optional porous separator, and an electrolyte to form the alkali metal-sulfur cell.