Thinner cell design development

To achieve lower cell cost and higher manufacturing capacity, Elcogen has developed and tested thinner cell design. Decreased substrate thickness allows not only to use less raw materials in production, but also to increase speed of tape-casting and sintering processes.

Thanks to fine optimisation of microstructure, mechanical strenght was doubled compared to previous generation cell with thikcer substrate, at the same time keeping extremely high performance level.

Fig. 1. SEM polished cross-section of “old” thicker B-type substrate cell (left) and “new” thinner C-type substrate cell (right).

Water-based slurry development for cell substrate

Next step in new cell design development is investigation of water-based binders for manufacturing of substrates. This approach will make cell not only cheaper thanks to low-cost water as a solvent instead of organics, but also considerably reduce CO2 emissions due to manufacturing process.

First experimental results obtained within BestInClassSOFCs project are very promising, giving high-quality homogeneous substrate layer. Elcogen will continue to develop the composition to investigate its potential application at large scale manufacturing.

Fig. 2. SEM polished cross-section of water-based thin half-cell with advanced porosity concept.

ALD barrier development

Currently, Elcogen together with its partners, professionals in thin layer deposition techniques, is inverstigating scalability of the ALD process, reduction of cost and manufacturing time. The final goal is to validate the new process with further pilot project tests of the new cells.

The GDC barrier layer is used to protect electrolyte against indesirable reaction with cathode, and SoA thick printed layer is a kind of a compromise. On one hand, you have to sinter it at high temperature to get it enough dense, but then it reacts with electrolyte, forming lower conductivity interdiffusion layer. On the other hand, sintering at lower temperature allows still some strontium zirconate formation and causes loss of efficiency.

A way out of this trade-off would be producing dense barrier layer at lower temperature. In the frame of the BestInClassSOFCs project, Elcogen is developing Atomic Layer Deposition (ALD) technique, usable for mass production. First preliminary results confirm success in overcoming limitations caused by regular thick GDC barrier layer.

Fig. 3. SEM cross-section of electrolyte-cathode interface of a cell with ALD barrier layer between them (left); Comparison of impedance spectra of a standard cell and a cell with ALD barrier layer. Test conditions: fuel side – dry H2; oxygen side – air; temperature – 650 °C; FU = AU = 20 %; I = 0.4 A/cm2 (right). .