NOVELTY - A solid-state battery device has current collector region, lithium-containing anode component, electrolyte material comprising garnet material (I), porous cathode material consisting essentially of garnet material (II), carbon bearing material, oxygen bearing source, and current collector structure. Garnet materials (I) and (II) comprise lanthanum-lithium-zirconium-containing composition. The porous cathode material has porosity of more than 30% and less than about 95%. The carbon bearing material comprises carbon material.    USE - Solid-state battery device (claimed). Uses include but are not limited to personal computer, video camera, portable telephone, smartphones, electric vehicle and hybrid vehicle.    ADVANTAGE - The solid-state battery device has excellent durability, and high power density and energy density.    DETAILED DESCRIPTION - A solid-state battery device has a current collector region, a lithium-containing anode component formed on the current collector region, an electrolyte material comprising garnet material (I) formed on the lithium-containing anode component, a porous cathode material consisting essentially of garnet material (II) formed on the electrolyte material, a carbon bearing material formed on the surface region of the porous cathode material, an oxygen bearing source which is in contact with the surface region of the porous cathode material, and a current collector structure configured to expose the surface region to the oxygen bearing source, and having preset conductivity. The electrolyte material has density of 80-100% of theoretical density associated with garnet material (I). Garnet materials (I) and (II) comprise lanthanum-lithium-zirconium-containing composition of formula: LaaLibZrcOdXe, where a is more than 2 to less than 4, b is more than 4 to less than 8, c is more than 1 to less than 3, d is more than 10 to less than 14, e is more than 0 to less than 2, and X is aluminum, antimony, tantalum, niobium and/or barium. The porous cathode material has porosity of more than 30% and less than about 95%. The carbon bearing material comprises carbon material.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of lithium air battery device.