Electrochemical characterisation and durability assessment of Ni/GDC-infiltrated metal-supported solid oxide cells for co-electrolysis operation

Solid Oxide Cells represent a promising solution for the efficient production of green syngas through co-electrolysis of H 2 O and CO 2 , playing a crucial role in sustainable carbon-neutral fuel synthesis. This study presents for the first time a detailed investigation of the performance and durability under co-electrolysis operation of metal-supported cells, featuring a mixed ionic-electronic conductor fuel electrode backbone infiltrated with Ni/GDC electrocatalyst. Electrochemical impedance spectroscopy identified five main processes contributing to performance loss, with fuel electrode kinetics being the primary limiting factor due to the reduced catalyst loading. An equivalent circuit model was proposed to fit impedance data and comprehensively evaluate degradation mechanisms. Long-term co-electrolysis durability tests revealed that key operating parameters – including current density, inlet fuel electrode gas composition, reactants conversion, and temperature – must be carefully chosen to minimise degradation. Notably, current density was found to be a critical operational limit, with accelerated degradation observed at −0.5 A/cm 2 . Higher H 2 O/CO 2 ratios and lower conversions improved stability, while temperature had an almost negligible effect within the tested operation range 650–700 °C. Optimal operating conditions require compromising between achieving the targeted syngas composition and maintaining cell stability, ensuring both efficient syngas production and sustained cell longevity. • Stable Metal Supported Cell co-electrolysis demonstrated at different conditions. • Degradation of 0.8 %/kh at 650 °C, 62:28:10H 2 O:CO 2 :H 2 , 0.31 A/cm 2 , 37 % conversion. • MSC's co-electrolysis durability investigated under varying operating parameters. • Equivalent electric circuit model proposed for MSC with LSFNT/FeCr fuel electrode. • Dense chromia scale effectively protects the metallic phase at both 650 and 700 °C.