Poster (After Call)

FZJ-2026-02782

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Multi-Mode Electrochemical Characterization of SOC Short Stacks under Steam- and Co-Electrolysis Operation

Golani, S. (Corresponding author)FZJ* ; de Haart, U.FZJ* ; Schäfer, D.FZJ* ; Samsun, R. C.FZJ* ; Eichel, R.-A.FZJ*RWTH*

2026

Abstract: The transition to carbon-neutral energy systems underscores the need to advance solid oxide cell (SOC) technologies capable of flexible and efficient operation across multiple modes. The Jülich F10 short-stack platform is a mature SOC stack technology with proven long-term stability across fuel-cell, steam electrolysis, and co-electrolysis modes. However, the mode-specific evolution of dominant loss mechanisms across the full FC–EL–Co-EL operating envelope remains poorly understood at the stack level, limiting the mechanistic foundation required for targeted performance optimization.To address this gap, this study presents a comprehensive multi-mode characterization of a short stack, quantifying performance differences and dominant electrochemical processes across different modes and operation conditions under harmonized experimental conditions. Advanced electrochemical impedance spectroscopy (EIS) coupled with distribution of relaxation times (DRT) analysis is employed to resolve mode-specific kinetic and transport contributions. The results reveal a progressive shift from charge transfer dominated losses in FC mode to gas transport and conversion-limited processes in EL and Co-EL modes, reflected in a systematic reduction of activation energy from ~0.58 eV in FC to ~0.36 eV in Co-EL operation. DRT analysis resolves four distinct processes, with the temperature-independent gas transport resistance growing substantially from FC to Co-EL. Under Co-EL conditions, fuel electrode gas transport and CO2 reduction kinetics were identified as the primary optimization targets, a distinctive mechanistic fingerprint of the ternary H2O/CO2/H2 gas environment. These findings provide novel insights into fuel-flexible SOC operation, establishing a mechanistic framework directly relevant to the development of SOC stacks for carbon-neutral fuel production through co-electrolysis and future biogas-based operation.

Keyword(s): Chemical Reactions and Advanced Materials (1st)

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Contributing Institute(s):

1. Grundlagen der Elektrochemie (IET-1)

Research Program(s):

1. 1231 - Electrochemistry for Hydrogen (POF4-123) (POF4-123)
2. 1232 - Power-based Fuels and Chemicals (POF4-123) (POF4-123)
3. PHOENIX - Verbundvorhaben PHOENIX: Im Fokus des Launch Space Power-to-X (PHOENIX) steht die Weiterentwicklung und Demonstration der vielversprechendsten P2X-Technologien. Der Forschungs- und Entwicklungsbedarf zur Realisierung nachhaltiger P2X-Technologien konzentriert sich auf die Elektrolyse als Schlüsseltechnologie (MWIDE-03SF0775A) (MWIDE-03SF0775A)

Appears in the scientific report 2026

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