A segmented-in-series high temperature solid-state electro-chemical device in which the cell segments are supported on a substrate comprising a porous metal layer for mechanical strength and a non-conducting porous layer for electrical insulation between cell segments is fabricated by co-sintering at least the metal substrate, insulating layer, an electrode and electrolyte. This allows for efficient manufacturing and the use of a thinner electrolyte (e.g., less than 40 microns thick) than in conventional designs, with a resulting performance improvement attributable at least in part to increased ionic conductivity. Alternative structures for the cell and interconnect repeat segments which are supported on a metallic substrate, as well as methods for producing said structures, specific compositions of the interconnect, and Al-containing compositions for the metallic substrate are described.
STATEMENT OF GOVERNMENT SUPPORT
 This invention was made with government support under Prime Contract DE-AC02-05CH11231 awarded by the United States Department of Energy to The Regents of the University of California for the management and operation of the Lawrence Berkeley National Laboratory. The government has certain rights in this invention.