IDEAL Cell: Work Package 4 "Dual Cell Realization"

Objectives

The RTD activities of this WP deal with the realisation of full dual cells with the aim to proof the concept of the innovative design. The main objectives are:

• To develop models of thermodynamic and kinetic aspects involved;
• To evaluate compatibility/reactivity of cell components;
• To fabricate the central membrane layer;
• To design and produce full dual cells;
• To test cells.

Description of work

Task 4.1: Physical and Electrochemical Modelling (Partner 1, Partner 2, Partner 3, Partner 4, Partner 9)

• Kinetics and thermodynamics (Partner 3, Partner 4, Partner 9)
  Time and space distribution of anionic current, protonic current, electric potential, temperature, pressure and water mass velocity can be calculated through solution of non–isothermal equations of change (i.e. equation of mass and charge continuity, equation of motion and equation of energy). The solution of these equations requires provision of several process parameters (transport parameters; kinetic parameters; morphological parameters);
• 3D percolation (Partner 1)
  Morphological mathematics and random sets approach (Boolean Scheme) will be used to tackle the 3D and percolation for the central membrane (CM) from 2D micrographs on cross section of the CM. Some tomography can eventually be attempted in order to integrate the fluid mechanics approach to propose different microstructures that will be modelled in view of optimizing the evacuation of water;
• Ions mass transfer characterization (Partner 2)
  Marker experiments will be performed for understanding the mechanisms involved by each component of the cell.

Task 4.2: Materials reactivity study (Partner 2)

The reactivity and compatibility of the cell components will be studied by analysis of the interface between the components after ageing in conditions similar to those of the working cell. Polished cross-sections will be observed from microscopic to nanoscopic level by SEM coupled with EDX, local XRD, SAM and localized XPS.

Task 4.3: Central membrane fabrication (Partner 1, Partner 3)

Composite central membrane layers with controlled microstructure and porosity obtained by using templating agents or pore formers (e.g. graphite, mais starch, latex spheres) will be realised by tape casting. The appropriate morphology (individuated in Task 4.1) will be tailored by the ratio Liq/Sol of the slurry, the volume fraction of the different powders and the pore former.

Task 4.4: Design of the dual cell (Partner 1, Partner 3, Partner 4)

Both size (i.e. thickness and height) and composition (i.e. volume fraction of anionic conductors, protonic conductors and voids) of the dual membrane are considered as key cell design parameters. The mathematical model of mass transfer and reaction developed in Task 4.1 will be used as a tool for optimisation of the dual membrane performance, including individuation of the optimal configuration for fast ion transfer and water transfer across the membrane.

Depending on the properties of each component, partners will determine the geometry of the dual cell (diameter, thickness of each component) that will be appropriate for testing and compare the Dual Cell properties with those of existing SOFC cells. If the values are lower, but the concept proven (water molecule at the central membrane: GO/NO GO decision), directions for improvement will be the object of the Midterm workshop, before tackling the optimization phase in WP5.

T4.5: Forming of the dual cell (Partner 1, Partner 2, Partner 3, Partner 4, Partner 8)

• Partner 1 will provide the tape-casting process to shape the full dual cell or part of it;
• Partner 4 will apply its plasma spray capabilities for the fabrication of the dual cell;
• Partner 8 will operate by realising electrodes and electrolyte layer by screen printing;
• Partner 3 will realise the composite materials for the central membrane fabrication;
• Partner 2 will provide powders or slurries of advanced cathode material for the fabrication of the dual cell and the appropriate sintering treatment conditions.

T4.6: Testing of the full dual cell (Partner 4, Partner 5)

Full dual cells prepared in Task 4.5 will be electrochemically characterized and tested by performing I-V characteristics and impedance spectroscopy measurements. Operating parameters such as gas flow and temperature will be varied to study their influence on the cell performance. Calibration measurements will be done for elimination of the parasitic inductance. Selected EIS measurements will be analysed by Differential Impedance Analysis with the aim to obtain information about the optimization of the standard full dual cell.

Deliverables

• D4.1 Technical report on the Dual Cell performance (Year 2).