A method of producing a powder mass for a lithium battery, the method comprising: (a) Providing a solution containing a sulfonated elastomer dissolved in a solvent or a precursor in a liquid form or dissolved in a solvent; (b) dispersing a plurality of particles of an anode active material in the solution to form a slurry; and (c) dispensing the slurry and removing the solvent and/or polymerizing/curing the precursor to form the powder mass, wherein the powder mass comprises multiple particulates and at least a particulate is composed of one or a plurality of particles of an anode active material being encapsulated by a thin layer of sulfonated elastomer having a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 800%, and a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm at room temperature.