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

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 (La _0.75Sr_0.25)_0.95MnO_3+δ (LSM). The conductivity of LSM-15 wt% Al₂O₃ composite CCCL decreases from 141.6 S cm^-1 to 23.7 S cm^-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-15 wt% 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-15 wt% Al ₂O₃ 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-15 wt% Al₂O₃ CCCL is nearly 1/7 of the unit cell with pure LSM being discharged at a constant DC of 0.32 A cm^-2 for about 100 h. Consequently, the addition of adhesive to CCCL is much more conducive to improve the long-term stability of the stack operation.