Optimized SOFC/SOEC joining and conditioning process

The production of solid oxide cell (SOxC) stacks - whether for solid oxide fuel cells (SOFC) or solid oxide electrolysis cells (SOEC) - involves numerous complex steps. One crucial phase is the so-called joining and conditioning process at 800°C to 1000°C. In this step, the individual cells are permanently joined together by thermal and mechanical treatments and the use of glass seal.

Significant material changes occur during this process: Ceramic cavities become denser, the binder is removed and the glass seal melts, creating a stable bond between the cells. The efficiency and quality of this process are crucial for the functionality of the finished stacks.

To optimize this process, an innovative impedance-guided method was developed. The electrical impedance of the cells or cell groups is not only used for final quality control, but also for real-time control of the joining and conditioning process. This offers the advantage that the control of the entire process is no longer based on fixed time specifications, but is dynamically adapted to the actual condition of the cells.

Use of electrochemical impedance spectroscopy (EIS)

The process is monitored and controlled using multi-channel electrochemical impedance spectroscopy (EIS). The multi-channel EIS meter from SIVONIC allows the impedance to be measured synchronously over different frequencies, providing valuable information about the chemical reactions and electrical and mechanical properties within the cells. Based on tests, specific impedance curves can be defined and integrated directly into series production. This represents an important step forward, as machine learning is used to optimize production processes.

Integration into the production lines

Another key aspect is the integration of the EIS meter into industrial production lines. The EIS meter from SIVONIC is characterized by high robustness, precise measurement accuracy and reliable performance under demanding production conditions. In addition, industrial interfaces enable seamless communication with existing process control systems, allowing the recorded data to be processed in real time.

By detecting deviations and potential errors in the conditioning process at an early stage, the EIS meter helps to minimize waste and maximize production yield. This proactive process monitoring not only significantly reduces conditioning time, but also improves plant utilization and reduces energy consumption.

SIVONIC has many years of experience with the use of EIS meters in joining control and has helped to reduce the joining time of SOxC stacks.

Conclusion

The optimized joining and conditioning process using electrochemical impedance spectroscopy represents a significant advance in the production of SOxC stacks. The combination of precise real-time control, robust EIS measurement technology and seamless integration into existing systems enables more efficient, resource-saving and higher-quality production.