Investigation of a Spinel‐forming Cu‐Mn Foam as an Oxygen Electrode Contact Material in a Solid Oxide Cell Single Repeating Unit

Abstract

A critical issue in state‐of‐the‐art solid oxide cell stacks is the contacting of the oxygen electrode. The commonly used ceramic contact layers are applied in a green state and cannot be sintered properly, due to compliance limitations arising from other stack components like sealing glasses and steels. The consequence is a low layer and interface strength. A metallic copper manganese foam, which is oxidized under operation conditions into a conductive Cu1+xMn2–xO4 spinel, is presented in this work as a viable contact solution. The foam has been electrochemically tested in a single repeating unit setup for 350 hours of constant operation, followed by dynamic conditions with thermal cycles. After operation, a micro structural analysis using scanning electron microscopy, energy dispersive X‐ray spectroscopy and X‐ray diffraction was carried out. It was confirmed that after oxidation/operation the manganese solely formed a CuMn‐spinel phase, mixed with a CuO phase. A separate Mn‐oxide phase was not found. The conductivity and contacting of the foam was sufficient for > 350 h of SOFC operation. With an initial serial resistance comparable to single cell tests using gold foil as contact material and moderate degradation rates, the CuMn foam presented itself as an interesting cathode contact solution.

Three‐dimensional Modeling and Performance Optimization of Proton Conducting Solid Oxide Electrolysis Cell▴

“…The mass and species conservation equations imply the general changes of mass and gas composition caused by chemical and electrochemical reactions, as shown in Eqs. (14) and (15):…”

“…Zielke et al. 14 successfully applied Cu‐Mn metal foam as current collector of SOFC. The metal foam showed good long‐term stability in the oxidizing environment.…”

“…The key to successful application of metal foam in the cathode is to find suitable metal foam, which is compatible with its neighboring components and is not easy to oxidize. Zielke et al [14] successfully applied Cu-Mn metal foam as current collector of SOFC. The metal foam showed good long-term stability in the oxidizing environment.…”

Interface Fracture Energy of Contact Layers in a Solid Oxide Cell Stack

“…Recently, the use of metallic CuMn or CuNi alloy foam as a new type of contact layer was suggested [25][26][27]. The flexibility of these foams in the metallic state allows for greater manufacturing tolerances, while the highly porous structure is ideal for gas permeation.…”

Thermal, mechanical, and electrical properties of LSCo/mullite composite contact materials for solid oxide fuel cells

“…1 Co 2 O 4 nanosized coated La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 powders, 12 superconducting materials of YBa 2 Cu 3 O 7− x , 13 LaNi 0.6 Fe 0.4 O 3 and La 0.8 Sr 0.2 FeO 3 , 14 Mn‐Co and Ni–Co metal powders, 15 LaNi 0 . 6 Co 0.4 O 3− δ dip‐coated Fe–Ce mesh, 16 glass‐La 0.85 Sr 0.15 MnO 3 and glass‐Sm 0.5 Sr 0.5 O 3 composites, 17 spinel‐forming Cu–Mn metallic foam, 18 and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 –Cu 2 O composite 19 . The issues of cathode contact materials have also been discussed in review papers 20‐21 .…”