Eliminating degradation in solid oxide electrochemical cells by reversible operation.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid oxide electrochemical cells (SOCs) offer dual functionality for energy storage and fuel conversion.
• Widespread adoption of SOCs is limited by long-term stability issues, especially under high current densities.

Purpose of the Study:

• To investigate and overcome the irreversible degradation mechanisms in SOCs during high-current-density electrolysis.
• To demonstrate a method for enhancing the long-term stability of SOCs.

Main Methods:

• Subjecting SOCs to continuous steam electrolysis at high current density (1 A cm⁻²).
• Implementing reversible cycling between electrolysis and fuel-cell modes over 4,000 hours.
• Analyzing microstructural changes and ohmic resistance at the oxygen electrode/electrolyte interface.

Main Results:

• Continuous electrolysis at high current density initially caused severe microstructural deterioration and increased ohmic resistance.
• Reversible cycling between electrolysis and fuel-cell modes completely eliminated microstructural damage.
• Ohmic resistance slightly improved after 4,000 hours of reversible cycling, contrary to expectations.

Conclusions:

• Reversible cycling is a viable strategy to eliminate degradation in SOCs, previously thought to be irreversible.
• This approach enables the application of SOCs for high-rate renewable electricity storage.
• The findings necessitate a re-evaluation of degradation mechanisms in SOCs.