TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The thermal energy storage material further comprises a void space, disposed in the phase changing salt pellet. The phase changing salt pellet is sodium chloride, sodium nitrate (both preferred), aluminum phosphate, ammonium carbonate, ammonium chloride, cesium carbonate, cesium sulfate, calcium citrate, calcium carbonate, calcium chloride, calcium hydroxide, calcium oxide, calcium phosphate, calcium saccharate, calcium sulfate, cerium phosphate, chromic chloride, iron phosphate, lithium carbonate, lithium sulfate, magnesium chloride, magnesium sulfate, manganese chloride, manganese nitrate, manganese sulfate, potassium acetate, potassium carbonate, potassium chloride, potassium hydroxide, potassium phosphate, rubidium carbonate, rubidium sulfate, disodium tetraborate, sodium acetate, sodium bicarbonate, sodium bisulfate, sodium borate, sodium carbonate, sodium citrate, sodium hydroxide, sodium percarbonate, sodium persulfate, sodium phosphate, sodium propionate, sodium selenite, sodium silicate, sodium sulfate, sodium tellurate, sodium tetraborate, sodium thiosulfate, strontium hydrophosphate, zinc acetate, zinc chloride and/or mixture of lithium carbonate or sodium carbonate. The surface roughener is nickel or silicon carbide. The metal oxide encapsulant is silicon dioxide, titanium dioxide, zinc oxide, calcium oxide, barium oxide, titanium dioxide-silicon dioxide composite, cerium dioxide, iron(III) trioxide, aluminum(III) oxide, magnesium oxide, lithium cobalt dioxide, lithium nickel dioxide, zinc oxide, zirconium dioxide, lithium titanium oxide, lithium aluminum manganese oxide, lithium nickel manganese oxide, lithium dimanganese tetraoxide and/or indium tin oxide. The graphene-metal oxide composite is graphene-silicon dioxide. The phase changing salt pellet is: surface functionalized, further comprising hexane and silane functionalization; cylindrical, spherical or oblong; and a cylindrical pellet having a porosity of 1-5% or a spherical pellet having a porosity of 22-29%. The void space is 15-35% of the size of the phase changing salt pellet. The void space is evacuated of ambient air. The phase changing salt pellet is made either by using power press or a pelletizer. The sol-gel graphene-silicon dioxide precursor is cured at 250 degrees C at a rate of 4 degrees C/minute for 2 hours. Preferred Method: The method further comprises: heating the phase changing salt pellets up to 250 degrees C for 2 hours at 4 degrees C/minutes; adding an additive to the polyimide prior to coating the exterior surface of the phase changing salt pellet in a polyimide, where the additive is nickel powder, silicon carbide, or carbon; forming a void space in the phase changing salt pellet prior to polyimide coating, where the void space is formed by drilling, briquetting, or die casting the pellet with a void space; reducing the pressure in the void space, comprising inserting a metal wire into the phase changing salt pellet during fabrication of the pellet, heating the phase changing salt pellet, removing the metal wire from the phase changing salt pellet, permitting heated gases to escape from the void space, and applying the polyimide coating to the phase changing salt pellet to seal the void space; and functionalizing the surface of the phase changing salt pellet, comprising soaking the phase changing salt pellet in a solution of hexane and silane for 24 hours prior to applying the polyimide coating to the phase changing salt pellet. The exterior of the polyimide coating is encapsulated in silicon dioxide or a graphene-silicon dioxide composite, and the method further comprises: obtaining a sol-gel silicon dioxide precursor, where the sol-gel silicon dioxide precursor is tetraethyl orthosilicate or tetraethyl orthosilicate containing graphene; mixing the tetraethyl orthosilicate with 3-aminopropyltriethoxy silane to form a silicate precursor; placing the polyimide-coated phase changing salt pellets into the silicate precursor; heating the silicate precursor; adding ethanol and hydrochloric acid to the silicate precursor; permitting the silicate precursor to hydrolyze for 5-10 minutes; neutralizing the silicate precursor with sodium hydroxide; and permitting the sol-gel silicon dioxide precursor to encapsulate the polyimide coated phase changing salt pellet.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polyimide coating is cured at a temperature of up to 250 degrees C, preferably 220-250 degrees C for 2 hours. Preferred Method: The polyimide coating is further coated by a process comprising: mixing the polyimide with N-methyl 2-pyrrolidinone and a plasticizer organic solvent; applying a thin layer of the N-methyl 2-pyrrolidinone and polyimide mixture onto the phase changing salt pellet by dip coating, spray coating, or brushing; and curing the polyimide layer.