The influence of double-layered cathode on contact resistance and electrical performance of solid oxide fuel cells self-supported by anodes

For intermediate-temperature solid oxide fuel cells self-supported by anodes, the contact resistance derived from the interfaces of cathode/electrolyte or cathode/current-collecting layer could be a restrictive factor for cell's performance improvement. In order to reduce the contact resistance, a double-layered cathode, other than traditional single-layered cathode, is introduced in solid oxide fuel cells. The double-layered cathode is composed of a coarse-particle outer layer which makes the cathode fully contact with silver current-collecting layer and a fine-particle inner layer which alleviates the structural difference between the coarse & porous cathode and the dense & smooth electrolyte. It has been proved that the cell contact resistance with double-layered cathode was significantly decreased, only 1/13 to 1/6 of single-layered coarse-particle cathode or approximately 1/5 of single-layered fine-particle cathode. Accordingly, the electrical performance has been elevated from 0.030, 0.064 and 0.111 W cm− 2 to 0.101, 0.170 and 0.284 W cm− 2 at different operational temperatures of 550, 600 and 650 °C, respectively.