Factors of cathode current-collecting layer affecting cell performance inside solid oxide fuel cell stacks

• CCCL can enlarger the contact real area at interface to improve cell performance.
• Better SRM of CCCL to its neighboring components contributes to higher performance.
• SRM of CCCL to active cathode exhibits larger contribution than that to interconnect.

Factors of cathode current-collecting layer (CCCL) affecting cell performance are studied by investigation of solid oxide fuel cell (SOFC) stacks with various (La0.75Sr0.25)0.95MnO3−δ (LSM) as CCCL in-suit. A larger real contact area between cathode and interconnect appears when the LSM is coated on cathode side as CCCL through characterization of a 2-cell stack. The result reveals that the real contact area depends on the surface roughness match (SRM) between CCCL and its neighboring components (active cathode and interconnect). A 6-cell stack using CCCLs with various levels of surface roughness is assembled and characterized further. The results show a higher electrical output performance of the stack repeating unit can be obtained when the surface roughness of the CCCL matches that of its neighboring components better, i.e. the surface roughness match (SRM) is the factor of cathode current collector affecting cell performance inside stack. Accordingly, the cell performance inside SOFC stack can be regulated by designing the SRM to its neighboring components.