Design and performance of Sr- and Co-free GDC-infiltrated LaNiO3 perovskite/La2NiO4 Ruddlesden–Popper structure multilayer cathodes for solid oxide fuel cells

Abstract

Solid oxide fuel cells (SOFCs) require high operating temperatures to compensate for the sluggish oxygen reduction reaction and to enhance ionic conductivity of oxygen. Although high performance can be achieved at elevated temperatures, long-term operation under such conditions can accelerate system degradation and compromise durability by promoting material deterioration and chemical side reactions between fuel cell components. Research has been conducted to lower the operating temperature of SOFCs. However, high-performance cathode materials, including strontium (Sr) and cobalt (Co), form secondary phases at high operating temperatures, which degrade cell performance. Therefore, Sr- and Co-free lanthanum nickelate (LNO) is a good cathode material with satisfactory material properties such as electronic conductivity and oxygen surface exchange kinetics for fuel cell cathodes. In this study, a multilayer composite cathode based on the perovskite and Ruddlesden–Popper crystal structures of LNO is proposed. In addition, high performance was achieved by introducing gadolinium-doped ceria electrolyte nanoparticle infiltration and a flash light sintering (FLS) process to secure ion-conductive pathways while suppressing particle growth and side reactions. Using the multilayer LNO cathode proposed in this study, power densities of 1.7 and 0.83 W/cm2 were achieved at 750 °C and 650 °C, respectively.