Achieving 360 NL h^-1 hydrogen production rate through 30-cell solid oxide electrolysis stack with LSCF-GDC composite oxygen electrode

A 30-cell solid oxide electrolysis (SOE) stack consisting of 30-cell planar Ni-YSZ hydrogen electrode-supported single cell with La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ-Ce_0.9Gd_0.1O₁₉₅ (LSCF-GDC) composite oxygen electrodes, interconnects, and sealing materials was tested at 750 °C in steam electrolysis mode for hydrogen production. The direction of gas flow in the stack was a cross-flow configuration, and the stack configuration was designed to open gas flow channels at the air outlet. The electrolysis efficiency of the stack was higher than 100% at 90/10H₂O/H₂ ratio under <0.5 A cm^-2 current density. During hydrogen production, the stack was operated at 750 °C under 0.5 A cm^-2 constant current density for more than 500 h with 4.06% kh^-1 degradation rate. Up to 73% steam conversion rate and 91.6% current efficiency were obtained; the net hydrogen production rate reached as high as 361.4 NLh^-1. Our results suggested that the SOE stack that was designed with LSCF-GDC composite oxygen electrode could be used to conduct large-scale hydrogen production.