High Performance and Stability Solid Oxide Electrolysis Cell without Hydrogen as Safe Gas

Primary Author: Martinus Dewa

Faculty Sponsor: Su Ha

 

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

 

Abstract:

 

Solid oxide electrolysis cell (SOEC) is a device that can transform CO2 and water into hydrogen (H2) and carbon monoxide (CO) using electricity through co-electrolysis process. H2 is often added during the SOEC operation as a safe gas to prevent the SOEC degradation. Removing H2 from the system can reduce the capital cost of the process. Nickel (Ni)/yttria-stabilized zirconia (YSZ) is a state-of-the-art electrode material for SOEC due to its good catalytic performance and electrical conductivity. However, many researchers claimed that it will rapidly deactivate under co-electrolysis without hydrogen since the Ni can be oxidized and becomes electrically non-conductive. CuFe2O4 has been recently investigated to substitute Ni/YSZ in SOECs since it has better stability under highly oxidizing condition such as co-electrolysis.

We fabricated the SOEC using both Nickel (Ni)/yttria-stabilized zirconia (YSZ) and CuFe2O4 by screen printing method. The electrochemical performance was measured under 1:1 ratio of CO2 and H2O at 800°C.

Our Ni/YSZ cell shows a decent performance of -400 mA/cm2 at 1.5 V and was stable after 24 h. However, Ni/YSZ requires activation by H2 during start up. CuFe2O4 cell can run without H2 activation and shows a slightly better performance of -475 mA/cm2 at 1.5 V. However, the stability was lower due to interface compatibility. Applying an additional La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) barrier layer successfully solved the stability issue, but electrochemical performance is compromised (-275 mA/cm2). Therefore, optimization of the design and fabrication method for the CuFe2O4 cell needs to be conducted to get both good performance and stability.