Towards sustainable interconnects for solid oxide cells: An integrated technical and environmental evaluation of coating methods

This work presents a comprehensive evaluation of three industrially relevant coating processes – atmospheric plasma spraying (APS), wet powder spraying (WPS), and electrophoretic deposition (EPD) – for the application of MnCo_1.9Fe_0.1O₄ (MCF) spinel-based protective layers on solid oxide cell (SOC) interconnects. Using Crofer-type ferritic stainless steels as substrate, the coatings were assessed with respect to their technical performance and environmental impact. Microstructural characterization, topography analysis for relevant interconnect structures, and mid-term exposure tests at 800 °C in air confirm that all three methods can produce uniform, well-adhering, and protective coatings compatible with SOC stack integration. While APS serves as a technologically mature reference, the suspension-based techniques WPS and EPD demonstrate comparable protective functionality after suitable thermal treatments. Furthermore, life cycle assessment reveals significant sustainability benefits for the newer methods – especially EPD – due to lower energy demand and enhanced material efficiency. The results highlight WPS and EPD as promising, environmentally advantageous alternatives for large-scale application of protective interconnect coatings in SOC systems.