CFY-Stack Technology: The Next Design

Abstract

The stack concept of electrolyte supported cells is applicable for both, SOFC as well as SOEC. High power densities and efficiencies comparable to stacks based on anode supported cells can be achieved, however, in unison with higher robustness. Incorporating an electrolyte made of fully scandia-stabilized zirconia paired with chromium-base CFY interconnects of matched CTEs, a feasible stack concept was created with the focus on long-term stability in regard to high temperature corrosion and thermal cycling. Onward development of the stack design as well as stack data of more than 20,000 hours of a single stack are presented. Using the same material combinations and the same footprint as for the MK351-design, the newly developed MK352-design allows for easier stack assembling and system integration. Slight modifications in interconnect design enable lower pressure drops over the stack, which, paired with enhanced tolerance chains lead to enhanced stack performance, especially in regard to system cycling.

Co-Electrolysis with CFY-Stacks

“…The MK352-stacks have well matched materials like CFY and 10Sc1CeSZ with the latest stack component technology in the field of cells and glass sealing. The cross flow design with internal gas and open air manifolds offers the possibility of designing compact stacks and systems (13,14,16,19). It allows an easy gas sealing at the end plates and a uniform air distribution over all cells by external manifolds.…”

“…The explosion view of the stack in Figure 5 shows the low amount of single parts and their easy assembly to a stack. The stacks were proven in SOFC operation for more than 20,000 h with an overall degradation rate of ∆P/P 0 =0.7%/1,000 h (∆ASR=20 mΩcm²/1000 h), more than 120 thermal cycles without flushing gas with ∆P/P 0 =0.5 %/10 cycles (13,19) and are commercially available. The sealing with semi-crystallizing glass with adjusted thermal expansion leads to a tight stack which can be handled at room temperature without any compression.…”

“…Especially with the MK352 design an improved stack platform was created. Results on SOFC and steam based SOEC operation were presented elsewhere (13)(14)(15). In this paper the results of operation in co-electrolysis mode are presented and discussed.…”

Co-Electrolysis CFY-Stack Operation and Integration for Carbon Capture and Utilization

“…Stacks with metallic CFY interconnect in Mk352 design have been used for electrolysis and co-electrolysis operation. Mk352-stacks have cross flow design with internal gas and open air manifolds and offers the possibility of compact packaging in stack modules for high power systems (6)(7)(8)(9). End plate design allows an easy gas sealing to external fuel manifold and a homogenous cooling of repeat units by uniform air distribution with low pressure drop over air compartment.…”

Development of a SOFC Power Generator for the Indian Market

“…Figure shows a 30‐cell CFY stack assembled at the pilot manufacturing line at IKTS. The robustness of CFY stacks has been demonstrated in various tests over more than 20,000 hours and 120 start/stop‐cycles, showing a power degradation rate below 0.7% per 1,000 hours and 0.5% per ten cycles, respectively . CFY stacks have been adopted for system integration by various external research partners and companies, e.g., Convion Ltd. of Finland .…”