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

Abstract

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.