NOVELTY - An electrochemical cell structure, comprises ionically conductive protective architecture (104) on first surface of the anode (102), having active metal ion conducting separator layer (106) comprising non-aqueous anolyte, and impervious ionically conductive layer (108) chemically compatible with the separator layer and with aqueous environments, and in contact with the separator layer.    USE - The cell structure is used in battery cell which is primary or rechargeable cell, e.g. for production of hydrogen for use in a fuel cell (claimed).    ADVANTAGE - This protective architecture prevents the active metal from deleterious reaction with the environment on the other (cathode) side of the impervious layer.    DETAILED DESCRIPTION - An electrochemical cell structure, comprises an anode comprising active metal, active metal-ion, active metal alloying metal, or active metal intercalating material; and an ionically conductive protective architecture on a first surface of the anode. The architecture comprises an active metal ion conducting separator layer comprising a non-aqueous anolyte, the separator layer is chemically compatible with the active metal, and in contact with the anode, and an impervious ionically conductive layer chemically compatible with the separator layer and with aqueous environments, and in contact with the separator layer.    INDEPENDENT CLAIMS are also included for:    (A) a battery cell (200), comprising an active metal anode; a cathode structure; and an ionically conductive protective architecture on a first surface of the anode, and comprising an active metal ion conducting separator layer comprising a non-aqueous anolyte, the separator layer being chemically compatible with the active metal, and in contact with the anode, and impervious ionically conductive layer chemically compatible with the separator layer and the cathode structure, and in contact with the cathode structure;    (B) a method of providing for the shut down of an electrochemical cell in the event of structural failure comprising providing in the anolyte a monomer for a polymer that is insoluble or minimally soluble in water and in the catholyte a polymerization initiator for the monomer; and    (C) a method of making a battery cell comprising providing the following components, an active metal anode; a cathode structure; and an ionically conductive protective architecture on a first surface of the anode, the architecture comprising an active metal ion conducting separator layer comprising a non-aqueous anolyte, the separator layer being chemically compatible with the active metal, and in contact with the anode, and an impervious ionically conductive layer chemically compatible with the separator layer and the cathode structure, and in contact with the cathode structure; and assembling the components.    DESCRIPTION OF DRAWING(S) - The figure is a schematic illustration of a battery cell incorporating an ionically conductive protective interlayer architecture.    Anode (102)    Protective architecture (104)    Separator layer (106)    Ionically conductive layer (108)    Current collector (110)    Battery cell (200)