Design and realization of IT- and HT-SOFC fuel cell technologies

Axis animator : Pascal Briois, MCF HDR

The major problem of Solid Oxide Fuel Cell is their rather high operating temperature: nowadays devices operate at around 1273 K. Such a high temperature is a severe limitation in terms of materials selection for the anode/electrolyte/cathode (thermo-mechanical compatibility, chemical stability,…), cells sealing and resulting limited lifetime of the stack. The cost of each component of the state of the art is very expensive. The solution proposed are to reduce the operating temperature to an intermediate domain (around 873-1073 K) without a significant decrease power density (or increase the cell performance). The state of the art is Yttria Stabilised Zirconia for the electrolyte, a Ni-YSZ cermet for the anode and perovskite structure lanthanum manganite for the cathode.

The specifications of each component for SOFC application are summarized in the following table:

The objective of decreasing the operating temperature of SOFC’s can be achieved via two main ways: by elaborating the standard material as a thin films and/or by developing new materials with higher properties around 1073 K than standard materials at 1273 K, including the use of protonic conductor as new electrolyte material (Proton Conductor Fuel Cell).

Different research axes of the FC LAB research federation

  • Deposition of standard material as thin films: YSZ, gadolinia doped ceria (GDC), Ni-YSZ, LSM…
  • Synthesis of new cathode (K2NiF4 structure and electrolyte materials (anionic conductor : Lanthanum silicate, … protonic conductors (figure 1) : yttrium doped barium cerate (BCY),  barium zirconate (BZY) and strontium zirconate (SZY)…),

Figure 1: SEM fractogrphies  of protonic conductors after annealing treatment at 873K/48 h

  • Protective coating of interconnectors,
  • Synthesis and characterization of single cells (figure 2).

Figure 2: SEM observation of single SOFC on anode support (electrolyte ; PVD, cathode : Screen Printing) Cell performance at 1073 K

Experimental devices of IRTES-LERMPS used for the FCLAB research federation

  • Industrial surface treatment devices: thermal spraying (figure 3) and magnetron sputtering (figure 4),
  • Furnace (up to 1473 K),
  • Structural and microstructural characterization: SEM, XRD, DSC…
  • Electrochemical characterization under controlled atmosphere: four point probe technique, electrochemical impedance spectroscopy (half-cell test).

Figure 3 : Thermal spraying device
Figure 4 : Magneton sputtering devis

 

Futur research

Future research planned for the axis « Design and realisation of IT- and HT-SOFC devices » in the short and medium term focus on four different points:

1) Modeling of SOFC synthesized by thin film technologies,
2) Manufacture and characterization a SOFC stacks synthesized by PVD and/or thermal spraying,
3) Synthesis of single cell PCFC on anode support,
4) Long time test under real conditions (around several hundred hours) and post-mortem analysis of cells.

 

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