Effect of conductivity and adhesive properties of cathode current-collecting layer on cell performance inside stack for planar solid oxide fuel cells

Abstract

Effects of conductivity and adhesive properties of cathode current-collecting layer (CCCL) on cathode contact resistance and cell performance inside a solid oxide fuel cell (SOFC) stack during operation are investigated by adding Al2O3 to the CCCL of (La0.75Sr0.25)0.95MnO3+δ (LSM). The conductivity of LSM–15wt% Al2O3 composite CCCL decreases from 141.6Scm−1 to 23.7Scm−1 at 800°C, whereas its adhesion to SUS 430 interconnect and LSM–YSZ active cathode increases by 2.5 and 1.8 times, respectively. The area specific resistance (ASR) of SUS 430/CCCL/LSM–YSZ sandwich at 800°C is tested. The result shows that ASR of SUS 430/ LSM–15wt% Al2O3 /LSM–YSZ sandwich is approximately 2.5 times smaller than that of the SUS 430/LSM /LSM–YSZ sandwich. The maximum output power density (MOPD) of the unit cell with LSM–15wt% Al2O3 CCCL is slightly higher than that of the cell with pure LSM CCCL at 800°C. The degradation rate of the unit cell with LSM–15wt% Al2O3 CCCL is nearly 1/7 of the unit cell with pure LSM being discharged at a constant DC of 0.32Acm−2 for about 100h. Consequently, the addition of adhesive to CCCL is much more conducive to improve the long-term stability of the stack operation.