NOVELTY - A core-shell protonated material has a core material comprising a protonated compound having perovskite crystal structure and shell comprising a shell material in contact with the core material. The protonated compound has a proton concentration of 0.01% or more by equivalent site occupation of perovskite-oxygen site occupation in a perovskite oxide particle ceramic of the core-shell compound.    USE - Core-shell protonated material is used for composite proton conductive electrolyte for electrical energy storage device e.g. electrochemical capacitor, electrolytic capacitor, hybrid electrochemical-electrolytic capacitor, secondary solid state battery and batcaps, nanoparticle battery, thick film composition, and solid-state secondary cell (all claimed).    ADVANTAGE - The core-shell protonated material provides electrical energy storage device having high energy density.    DETAILED DESCRIPTION - A core-shell protonated material has a core material comprising a protonated compound having perovskite crystal structure and shell comprising a shell material in contact with the core material. The protonated compound has a proton concentration of 0.01% or more by equivalent site occupation of ABO3 perovskite-O-oxygen site occupation in a perovskite oxide particle ceramic of the core-shell compound. INDEPENDENT CLAIMS are included for the following:    (1) composite proton conductive electrolyte, which comprising a mixture of core-shell material and proton conductive ionomer;    (2) electrical energy storage device, which comprising core-shell protonated compound;    (3) nanoparticle battery, which comprises core-shell protonated material;    (4) thick film composition, which comprises core-shell protonated material and an ionomer; and    (5) solid-state secondary cell, which comprising an anode, cathode and proton conducting electrolyte. The electrolyte comprises a mixture of core shell protonated material, proton conducting ionomer and oxide dielectric dispersed between particle boundaries of the core-shell protonated material.