Electrochemical Performance and Durability of a Solid Oxide Cell with Nanoparticles-Modified Electrodes for CO₂ Electrolysis

Abstract

Solid oxide electrolysis cell (SOEC) is one of the most effective technologies for converting carbon dioxide to carbon monoxide using renewable energy sources. This work investigated the electrochemical performance and long-term durability of a Ni/yttria-stabilized zirconia (YSZ)-supported planar-type SOEC cell (CGO@Ni/YSZ|YSZ|CGO|LSC/CGPO@CGO) infiltrated with nano-catalysts for CO2 electrolysis. The Ni/YSZ fuel electrode was infiltrated with Ce0.8Gd0.2O2−δ (CGO) solution, and the porous CGO scaffold was co-infiltrated with La0.6Sr0.4CoO3-δ (LSC) and Gd, Pr co-doped CeO2 (CGPO) nano-sized electrocatalysts. The cells were operated at 800 °C and -1 A/cm2 for 1548 h with a mixture of 24 L/h CO2/CO (83/17) supplied to the fuel electrode and pure O2 to the oxygen electrode. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis were conducted. During the entire durability testing period, the cell voltage increased from 1246 mV to 1400 mV with a degradation rate of 99.1 mV/kh (7.95%/kh). Following the recovery after an unexpected power outage, the cell demonstrated an activation process over ⁓110 h, with a voltage decrease from 1337 mV to 1263.9 mV. Furthermore, the cell showed a much lower degradation of ohmic resistance R s (7.14 mΩ cm2/kh) compared to that of polarization resistance R p (129.05 mΩ cm2/kh). DRT reveals that the degradation originates from both electrodes. The present study reveals that it is crucial to carefully select the appropriate electrocatalyst candidate considering the specific operating conditions.