Intermediate-temperature solid oxide electrolysis cells with thin proton-conducting electrolyte and a robust air electrode†
A proton-conducting solid oxide electrolysis cell (H-SOEC) is a promising device that efficiently converts electrical energy to chemical energy. A H-SOEC offers a number of merits over oxygen-ion-conducting solid oxide electrolysis cells (O-SOECs). However, the development of H-SOECs is far behind that of O-SOECs, mainly due to technical challenges such as the stability of the electrolyte and electrode in a H2O-containing atmosphere under operating conditions and the fabrication of a thin electrolyte layer. In this study, BaZr0.8Y0.2O3−δ (BZY) electrolyte and a Sr2Fe1.5Mo0.5O6−δ (SFM) air electrode, both are stable in a H2O-containing atmosphere under operating conditions, are evaluated in H-SOECs. In addition, in order to improve the performance of H-SOECs, a thin BZY electrolyte layer (about 16 μm in thickness) and nano-scaled SFM–BZY air electrode are fabricated successfully, showing excellent SOEC performance (−0.21 A cm−2 at 600 °C) and achieving a faradaic efficiency of 63.6% at intermediate temperature.