Progress in SOC Development at Fraunhofer IKTS

Abstract

After long and successful development history of Solid Oxide Cells (SOC) continuous improvement in performance, longevity, manufacturing, and system integration it is necessary to bring this highly efficient technology to the market. The activities on material development and optimization at IKTS are focused mainly on enhancement of durability for SOFC, SOEC, and rSOC operation and on boosting the power density. During recent years considerable efforts on simplification and automation of cell and stack manufacturing processes have been addressed. The processes for electrode manufacturing have been adjusted for high yield automated printing on thin electrolytes with integrated quality control measures. Efficient ways for reduction of time and energy consumption for sealing process of SOC stacks have been found and demonstrated in pilot production as well as automated assembling of components to stacks was shown. The increasing interest in “green hydrogen” created multiple opportunities for SOEC technology to be considered as inherent part of industrial and chemical processes. IKTS pioneering work on coupled operation of SOEC module with Fischer-Tropsch reactor provided first demonstration of feasibility of this approach for wax production. However, high power electrolysis applications (>10 MW) will need new approaches for stack design and put higher requirements on durability.

Electrochemical Analysis of an Electrolyte-Supported Solid Oxide Cell-Based MK35x Stack during Long-Term Electrolysis Operation

“…A 10-cell stack of the Mk35x design with metallic CFY (∼94 mol % Cr, 5 mol% Fe, ∼1 mol% Y 2 O 3 ) interconnects developed by IKTS was operated in steam electrolysis. 8,16,17,19,21 The stack was manufactured at the IKTS pilot line and had a cross flow design with internal fuel gas and open-air manifolds. Figure 1 shows the exploded view of the stack components and their assembly.…”

“…7 The MK35x stack platform developed by IKTS is based on electrolyte supported cells (ESC) with chromium-iron-yttrium (CFY) interconnects. 8,[16][17][18][19][20][21] The stacks were initially developed for SOFC operation where they showed an average voltage decrease of 0.7%/kh for more than 20,000 h and are commercially available. 18 Here, the durability behavior of MK35x stacks tuned for operation in electrolysis mode is investigated in detail for more than 3000 h in order to obtain an in-depth understanding of the voltage evolution over time of the individual repeat units in the stack.…”

Small‐Scale Demonstration of a High‐Temperature Coelectrolyzer—Experimental Results and Model Validation

“…More details on stack design and general performance can be found in literature. [11][12][13] The stack module was designed for a nominal input power of P el,stack,nom,DC = 12 kW at a standard current density of i = 600 mA cm À2 .…”

“…To provide reliable data for upscaling of hydrogen or syngas production facilities, such models need to be validated under relevant conditions. For that purpose, the results from the small-scale demonstration plant are compared with models derived in earlier works of the authors, [10][11][12] showing a good applicability not only of the stack model but also of the assumptions chosen for the modeling of SOEL systems.…”

Lab‐Scale Demonstration of By‐Product Utilization in an Integrated Power‐to‐Liquid Process Applying Co‐Electrolysis

“…A ten‐cell MK352 SOEC stack with a rated power of P el,SOEL = 1 kW, designed and built at IKTS, [ 13 ] was chosen to be the core of the syngas production step. Due to the operating temperature of ϑ SOEL ≈800 °C, it was housed in an insulating hot box.…”