Fuel cells, calcia stabilized zirconia

A high temperature solid electrolyte fuel cell (SOFC) will be considered now. Modern SOFC technology employs calcia-stabilized zirconia as the support tube and yttria-stabilized zirconia as the solid electrolyte. In addition, special oxide ceramic materials are employed as electrodes and interconnection materials. These materials and the solid electrolyte are deposited as thin layers on the support tube by electrochemical vapor deposition. 

The high temperature electrolytes are mostly oxides of composition MO based upon the fluorite, structure. The best investigated is "calcia stabilized zirconia (CSZ) which consists of a solid solution of 12-15% CaO in ZrO. The addition of calcia transforms ZrO from the monoclinic to tne cubic (fluorite) structure and also introduces anion vacancies for charge compensation. Conduction is by 0 ion diffusion through anion vacancies and ZrO -CaO has a resistivity of 30 ohm-cm at 950 C. Trivalent cations may also be used to stabilise ZrO with resistivities at 950 C of 12 ohm-cm for ZrO -Y 0 and - 6 ohm-cm for ZrO -Yb O or ZrO -Sc O (Figure l). Staoilized zirconia is of interest as an electrolyte for fuel cells, but no battery applications have been proposed and the temperature of conduction is too high to be of real interest. 

And now briefly about modem Ukrainian fuel cell history Being based on many years positive experience in manufacture of real nano-sized zirconia powders with different stabilizers like yttria, calcia, scandia etc. and zirconia ceramics [8, 9] the first Ukrainian demonstrating model of zirconia fuel cell was made and exhibited by January 22, 2002 [10- 12]. It has realized 0.85 V and 0.5 V of electro motive forces with propane gas and ethanol respectively at their direct burning. 

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