CGO-Infiltrated Ni/YSZ SOEC Fuel Electrodes for Increased Carbon Tolerance During CO₂ Electrolysis

Solid Oxide Electrolysis Cells (SOEC) have the ability to operate as CO₂ electrolysis cells, reducing CO₂ to CO. Applying SOEC for CO₂ electrolysis should be done carefully, since processes including carbon deposition lead to decreased life-time. This study is investigating the effect of the fuel electrode overpotential on carbon deposition in the Ni/YSZ fuel electrode, and the effects of CGO infiltration of the fuel electrode on carbon deposition, on performance during CO₂ electrolysis. Long-term durability test shows an increase in degradation rate from 252 mV/kh to 467 mV/kh over a ∼50 h period at ∼1375 mV. The carbon deposition threshold is investigated through the potential-current response, where a bend around 1375 mV in the iV-curve led to a hysteresis effect. Raman spectroscopy of the long-term tested cell shows carbon deposition; the largest quantities are found near the fuel gas inlet and the amount decreases along the gas flow direction.