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Description
Solid oxide electrolysis cells (SOECs) are electrochemical systems enabling conversion of excess renewable energy via high-temperature steam electrolysis into hydrogen as energy carrier and sustainable fuel. Long-term degradation remains the main issue for the viability of this technology as a practical hydrogen production system. The concept of fuel-assisted SOEC relies on the supply of a low-cost fuel to the anode in order to reduce the operating potential of the cell and enhance the long-term stability of the anode/electrolyte interface [1,2]. In these configuration, conventional ceria-based buffer layers at the electrolyte/anode interface may not be applicable due to excessive chemical expansion on reducing oxygen partial pressure.
The present work explores pyrochlore-type Y2Ti2O7-based titanates as possible alternative to doped ceria in fuel-assisted SOECs. A series of Y2-xAxTi2-yByO7-δ (A = Ca, Mg; B = Mg, Zr, Mn) ceramics were prepared by solid state route. The materials were characterized by XRD, SEM/EDS and thermal analysis. Electrical studies included measurements of total conductivity as function of temperature and oxygen partial pressure (600-900°C) and determination of partial ionic and electronic contributions by the e.m.f. method (700-900°C). Thermochemical expansion was evaluated by controlled-atmosphere dilatometry at 600-900°C. The chemical compatibility at different temperatures was assessed in contact with yttria-stabilized zirconia solid electrolyte and selected oxygen electrode materials.
[1] G. Tao, B. Butler, A.V. Virkar, ECS Trans. 35 (2011) 2929.
[2] Y. Wang, T. Liu, L. Lei, F. Chen, J. Power Sources 344 (2017) 119.
| Speaker Country | Portugal |
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