Stability study of SOFC using layered perovskite oxide La_1·85Sr_0·15CuO₄ mixed with ionic conductor as membrane

Long-term stability is of significant importance to energy conversion devices including solid oxide fuel cell (SOFC). In this work, we apply a layered perovskite oxide La_1·85Sr_0·15CuO₄ (LSCO₄) mixing with ionic conductor Ce_0.8Sm_0.2O_2-δ (SDC) to get an ionic and electronic conductor composite (IECC) membrane SOFC for the sake of achieving a stable cell. The addition of proper ratio of LSCO₄ in the membrane improves cell performance. The IECC fuel cell reaches a stability of over 75 h at 550 °C under 100 mAcm⁻² and can resist multiple times of rapid heat-up and cool-down cycles. The factors that influence cell stability are investigated. The covalence states of the IECC are found to change firstly but stabilize after several hours of test. Resulting from anode Ni_0·8Co_0·15Al_0·05LiO_2-δ (NCAL) reduction, Li⁺ is found to migrate to the IECC membrane, leading to IECC membrane densifying and resultantly protecting the IECC from further reduction by hydrogen. However, the continuous online reaction of NCAL electrodes leads to the increase of charge transfer resistance as well as the decrease of gas diffusion pores in the electrode. This study provides important reference for designing stable IECC membrane fuel cell.