Simple upgrade and re-use of recycled YSZ from used solid oxide fuel/electrolyser cell component materials

In this work, a simple up-grading treatment of yttria stabilized zirconia (YSZ) recycled from solid oxide cells (SOCs) is presented. Indeed, recycled YSZ, issued from both the electrolyte and fuel electrode parts of end-of life cells, are composed of mixtures of monoclinic, cubic, and tetragonal phases. In situ powder X-ray diffraction from RT to 1100°C shown that these mixtures undergo structural transformation of monoclinic and cubic phases into tetragonal phase, whose conductivity is too weak to allow their direct use of as electrolyte material. Addition of commercial Y 2 O 3 to recycled powders enables to obtain 6YSZ, 8YSZ or 10YSZ compositions with homogenous yttrium distribution, grain growth and densification. Electrochemical impedance spectroscopy demonstrated an improved ionic conductivity in upgraded 8YSZ. The process was then applied to another powder issued from a mixture of SOC wastes, and a complete cell, delivering a convenient open circuit voltage and consistent power densities was finally prepared with the recycled and upgraded electrolyte.