Enhanced Performance of Protonic Solid Oxide Steam Electrolysis Cell of Zr-Rich Side BaZr(0.6)Ce(0.2)Y(0.2)O(3−δ) Electrolyte with an Anode Functional Layer

[Image: see text] Proton-conducting solid oxide electrolysis cells (H-SOEC) containing a 15-μm-thick BaZr(0.6)Ce(0.2)Y(0.2)O(3−δ) (BZCY622) electrolyte thin film, porous cathode cermet support, and La(0.6)Sr(0.4)Co(0.2)Fe(0.8)O(3−δ) anodes were fabricated using a reactive cofiring process at approximately 1400 °C. Steam electrolysis was conducted by supplying wet air to the anode at a water partial pressure of 20 kPa. The performance was evaluated using electrochemical measurements and gas chromatography. At 600 °C, the cells generated an electrolysis current of 0.47 A cm(–2) at a 1.3 V bias while the Faradaic efficiency reached 56% using 400 mA cm(–2). The electrolysis performance was efficiently improved by introducing a 40-nm-thick La(0.5)Sr(0.5)CoO(3−δ) (LSC) nanolayer as an anode functional layer (AFL). The cells with LSC AFL produced an electrolysis current of 0.87 A cm(–2) at a 1.3 V bias at 600 °C, and the Faradaic efficiency reached 65% under 400 mA cm(–2). Impedance analysis showed that the introduction of the AFL decreased the ohmic resistances and improved interfacial proton transfer across the anode/electrolyte interface and polarization resistances related to the anode reaction. These results demonstrate opportunities for future research on AFL to improve the performance of H-SOECs with Zr-rich BaZr(x)Ce(1–x–y)Y(y)O(3−δ) electrolytes.