Method of producing electrochemically stable elastomer-encapsulated particles of cathode active materials for lithium batteries

A method of producing a powder mass of a cathode active material for a lithium battery, the method comprising:

• (a) mixing an inorganic filler material and an elastomer or its precursor in a liquid medium or solvent to form a suspension;
• (b) dispersing a plurality of particles of said cathode active material in the suspension to form a slurry;
• and (c) dispensing the slurry and removing the solvent and/or polymerizing or curing the precursor to form the powder mass, wherein the powder mass comprises multiple particulates of the cathode active material and at least a particulate comprises one or a plurality of particles of said cathode active material being encapsulated by a thin layer of inorganic filler-reinforced elastomer having from 0.01% to 50% by weight of an inorganic filler dispersed in an elastomeric matrix material, wherein said encapsulating thin layer of inorganic filler-reinforced elastomer has a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 500%, and a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm and said inorganic filler has a lithium intercalation potential from 1.1 V to 4.5 V versus Li/Li+.