K doped LiNi0.8Co0.15Al0.05O2-δ electrode for solid oxide fuel cells operating at low temperatures down to 350 ℃

Abstract

Solid oxide fuel cells (SOFCs) can be an alternative candidate for power generation in the evolution of energy towards sustainability and low carbon emission. Lowering the operation temperature of SOFC is of great importance for its world-wide application. LiNi_0.8Co_0.15Al_0.05O_2-δ (NCAL) electrode has shown excellent performance at 400–600 °C. However, obtaining high catalytic activity together with decent durability at reduced temperature is still challenging. In this study, K doped NCAL (xK-NCAL, x = 0, 10, 20) is developed as the symmetrical electrodes of SOFC, and is proved to provide high power output. Fuel cells with 10 K-NCAL electrodes achieve a maximum power density of 812 mW cm⁻² at 450 °C and 93 mW cm⁻² at 350 °C. Pretreatment processes, such as preheating, H₂-air pretreatment, and I-V-P test pretreatment, are found to influence the performance of the cells as they affect the formation and migration of the Li/K-species in the cell. K doping in NCAL facilitates its reaction with H₂ as well as the production and migration of alkali species at reduced temperature, which are proved to be critical issues for the cell to be run at temperatures down to 350°C. The cell is operated for about 350 h. This study provides an effective strategy for designing high-performance electrodes for SOFCs operating at < 400 °C.