Formation of a thin-layer electrolyte for SOFC by magnetic pulse compaction of tapes cast of nanopowders

Abstract

From the analysis of the scientific and technical literature it is possible to determine the trend of development of technologies for preparation of thin films of solid electrolytes for SOFC as the most promising one. The use of powder compaction technologies and weakly agglomerated nanosized powders for this purpose has some advantages. The present study deals with physicochemical properties of electrolytes based on zirconia and ceria and electrochemical cells loaded with these electrolytes. Weakly agglomerated nanopowders with particles about 15 nm in size were produced by laser sputtering. Films 15–25 μm thick were obtained from nanopowders of the electrolytes by butyral resin slip casting. Uniaxial and radial magnetic pulse compaction of the cast films was performed at 0.1–1.6 GPa. The apparent density of the compacts accounted for 0.5–0.7 of the theoretical value. Sintering at temperatures of 900–1250 °C provided electrolytes having the relative density of 0.92–0.98. The analysis of the structure and the conductivity of the solid electrolytes, which was performed using samples shaped as flat thin disks 15–30 mm in diameter and 10 μm to 2 mm thick, and the examination of the electrochemical characteristics of the cells made of an ultrafine solid electrolyte in the form of tubes having the diameter of about 10 mm and walls 80–250 μm thick confirmed that the ceramic samples were gas-tight and had not laminations. The conductivity of, e.g. the YSZ electrolyte was 0.08–0.112 S cm −1. The electrochemical cells, which were tested in the regime of a fuel cell with a solid electrolyte synthesized using the proposed technologies, provided the specific power of about 1 W cm −2 at 800–850 °C even without optimization of the electrodes. Thus, the ultrafine solid electrolytes met the requirements imposed on SOFC ceramics.