Sulfur Tolerant LSCM-based Composite Cathode for High Temperature Electrolysis/Co-electrolysis of H2O and CO2

Abstract

The cathode performance of various LSCM-based composites for high temperature H2O electrolysis has been studied by examining their electrochemical behavior under current loading using three-electrode electrolysis cells with Pt as counter and reference electrodes. Experimental results among pure LSCM, LSCM–GDC, LSCM–YSZ and LSCM–(GDC–YSZ) have shown that LSCM-GDC exhibits the highest H2O electrolysis performance. The ratio between LSCM and GDC is further optimized and it is shown that the LSCM-GDC with 50–50 wt.% for each component exhibits the highest performance. Benchmarking with a 60–40 wt.% Ni-YSZ cathode have shown that the optimized LSCM–GDC cathode exhibits better performance for H2O electrolysis with a lower area specific resistance. Under a cathodic current of –0.1 A cm−2, the optimized LSCM–GDC cathode shows much slower degradation, about 10 times slower as compared to the Ni-YSZ cathode when exposed to 10 ppm of SO2 for up to 72 h. All the above electrochemical tests have been conducted at 800 °C and 70/30 pH2O/pH2. Without the use of reducing agent, the optimized LSCM–GDC cathode also shows promising performance for co-electrolysis of H2O and CO2 at high current densities and stable performance with 5 ppm of SO2 in the feedstock gas.