NOVELTY - An amorphous oxide-based compound (I), is new.    USE - As electrolyte medium (claimed) in electrochemical cell such as a battery cell.    ADVANTAGE - The amorphous oxide-based compound is produced by using relatively simple and inexpensive processes. The electrolyte medium is non-aqueous, non-liquid, inorganic, and compatible with lithium and lithium-containing compositions, and can be manufactured in thin-dimensioned and small-dimensioned configurations.    DETAILED DESCRIPTION - An amorphous oxide-based compound of formula (M1)w(M2)x(M3)y(M4)z (I), is new.    M1=at least one lithium-set element from a lithium set consisting of the alkali-metal family of the Periodic Table;    M2=at least one lanthanum-set element from a lanthanum set consisting of lanthanum, barium, strontium, calcium, indium, magnesium, yttrium, scandium, chromium, aluminum, lutetium, potassium, the alkali-metal family of the Periodic Table or the lanthanide series of the Periodic Table;    M3=at least one zirconium-set element from a zirconium set consisting of zirconium, tantalum, niobium, antimony, tin, hafnium, bismuth, tungsten, silicon, selenium, gallium or germanium;    M4=at least one oxygen-set element from an oxygen set consisting of oxygen, sulfur, selenium, or the halogen family of the Periodic Table of elements;    w, x, y, and z=positive numbers including various combinations of integers and fractions or decimals.    INDEPENDENT CLAIMS are included for the following:    (1) an electrolyte medium comprising at least one layer of amorphous lithium lanthanum zirconium oxide;    (2) preparation of the amorphous oxide-based compound (I); and    (3) synthesizing (M1) amorphous lithium lanthanum zirconium oxide involving producing a mixture by dissolving in a solvent, a first precursor solute comprising a compound of lithium, a second precursor solute containing a compound of lanthanum, a third precursor solute having a compound of zirconium and optionally polymers, and dispensing the mixture in a planar configuration and drying and curing to a dry phase.