Performance of CO₂ electrolysis using solid oxide electrolysis cell with Ni-YSZ as fuel electrode under different fuel atmospheres

ABSTRACT

High efficiency conversion of CO₂ can be realized in a solid oxide electrolysis cell. In this work, a flat-tube cell with symmetrical structure supported by Ni-YSZ fuel electrode was used to study the performance of high-temperature CO₂ electrolysis under different reducing gas components in the fuel electrode. The results indicated that in the H₂-CO₂ fuel electrode atmosphere, the instantaneous performance of CO₂ electrolysis is better, the polarization impedance is smaller, and the overpotential of CO₂ electrolysis is lower under the same partial pressure of oxygen (i.e., with the same open-circuit voltage). Compared with CO as the protective gas, it is easier to achieve a stable electrolytic voltage for the electrolysis of CO₂ under H₂ protection. In the H₂-CO₂ reaction atmosphere, when the proportion of protective H₂ increased from 25% to 75%, devastating irreversible degradation occurs at −300 mA/cm², while in the CO-CO₂ (71.7% CO-28.3% CO₂) reaction atmosphere, the similar degradation occurs at – 200 mA/cm². At – 200 mA/cm² constant-current electrolysis, the highest energy conversion efficiency can reach 171% (disregarding energy consumption for heating the gas) and 81.6% (disregarding energy consumption for heating air). This work provides a useful reference for the selection of atmosphere protection in CO₂ electrolysis based on Ni-YSZ electrode SOEC.

KEYWORDS:

• CO₂ electrolysis
• reducing atmosphere
• flat-tube structure
• SOEC

Acknowledgments

This work was supported by National Natural Science Foundation of China (U20A20251), Key R & D Program of Zhejiang Province (2021C01101) and “From 0 to 1” Innovative Program of CAS (No. ZDBS-LY-JSC021).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.