Improving the performance of LiNi0.8Co0.15Al0.05O2-δ electrode-based fuel cell through cathode modification

Abstract

LiNi0.8Co0.15Al0.05O2-δ (NCAL) is reported to provide dual catalytic activities of hydroxide reaction (HOR) and oxygen reduction reaction (ORR) in solid oxide fuel cell. However, it has been observed that the performance of NCAL symmetric electrodes undergoes a gradual decrease during fuel cell operation, especially the cathode, which was found to suffer from severe gas diffusion degradation. In this study, we tried to optimize the NCAL cathode by modifying the microstructure in order to increase the cathode performance under extended operation time. During the fabrication of SOFCs, various mass ratios of poly (methyl methacrylate) (PMMA) microspheres were introduced into the NCAL cathode as pore former. The affection of pore former ratio and its size on cell performance is investigated. Results suggest that properly increasing the porosity of the cathode is of significant importance for improving cathode performance, but additionally increasing the porosity of the anode by pore-former is not a wise choice. Besides, considering the oxidation of nickel foam at the cathode, comparative study on the application of nickel foam is carried out to understand its role. In addition, the performance of the cells over a continuous operation for hours has been studied to evaluate the effectiveness of the optimization method. This study provides reference for improving the performance of SOFC based on NCAL electrodes.