Polarized electrochemical vapor deposition for cermet anodes in solid oxide fuel cells

A new process originally developed for sensors shows promise for coating porous nickel substrates with a layer of yttria stabilized zirconia (YSZ) for cermet anodes in solid oxide fuel cells (SOFCs). Traditionally, the cermets are deposited using randomly interspersed nickel and stabilized zirconia powders. However, the conducting nickel is a mostly discontinuous phase and thus the conductivity is impeded. With this new polarized electrochemical vapor deposition (PEVD) technique, the deposition of a uniform layer of YSZ was demonstrated using a platinum substrate, which had previously been sintered to a continuous layer over the fuel cell electrolyte. Films deposited over a 24 h period with a −0.300 V applied potential were on average 1–3 μm thick. After 5 days, the film becomes fully dense with few large blocked pores. Preliminary EDX testing indicates that the amount of deposition product decreases away from the substrate, indicating that deposition and film growth commence at the triple phase boundary.