LSCM-GDC as composite cathodes for high temperature steam electrolysis: Performance optimization by composition and microstructure tailoring

Abstract

The double-doped perovskite La0·75Sr0·25Cr0·5Mn0·5O3-δ (LSCM) is a promising cathode material for solid oxide electrolysis cells (SOECs), but the poor catalytic activity limits its application. In this work, LSCM-Gd0.2Ce0·8O2-δ (GDC) bilayer cathodes are successfully prepared for high temperature steam electrolysis. The moderate addition of GDC to LSCM electrode improves the cell performance due to the formation of more oxygen vacancies and increased H2O adsorption capability. Moreover, particle size graded cathodes are further prepared based on the optimal composition, and the optimized cell achieves a remarkable current density of 2.36 A cm−2 at −0.1 V and 800 °C under non-reducing conditions. The well-connected and porous network effectively extends the length of triple-phase boundaries (TPBs) and facilitates the gas diffusion inside the electrode. Therefore, doping with a certain amount of GDC and optimizing the microstructure of electrodes are effective ways to enhance the electrocatalytic activity of the conventional LSCM-GDC cathode.