Cell Performance of Anode-Supported BaZr0.85Y0.15O3-δ/Carbonate Composite Electrolyte at Intermediate Temperature

Recently, proton-conducting based-protonic ceramic fuel cells (PCFCs) have received great attentions as sustainable power generators at the intermediate temperature, because of their higher ionic conductivity with lower activation energy as compared to the oxygen-ion-conducting electrolytes based solid oxide fuel cells (SOFCs). Among several perovskite-type proton conducting oxides, yttrium-doped BaZrO₃ (BZY) have exhibited considerable bulk proton conductivity with a high chemical resistance against CO₂ and H₂O in the intermediate temperature range. However, the manufacturing of porous electrode-supported dense BZY electrolyte cells virtually needs awfully difficult processes by the current SOFC technology due to its poor sinterability. Furthermore, high sintering temperature results in decreasing the proton conductivity of BZY with the BaO sublimation and low-conducting Y₂O₃-like phase formation. In addition, the BZY materials are still required to improve proton conductivity under the PCFC operating condition.

To achieve these goals, we have designed two-phase composite electrolytes consisting of a BZY matrix phase and a binary eutectic carbonate (Li–0.5Na)₂CO₃ phase in previous works. The conductivity of the composite electrolytes is higher than that of the BZY under the PCFC operating condition. Moreover, dense BZY composite electrolytes are fabricated with a carbonate phase at a remarkably low sintering temperature of 670 °C. Hence, in this work, anode-supported BZY/carbonate electrolyte cells are fabricated by the co-pressing technique with the Ni-cermet anode and as lithiated NiO cathode to confirm this composite electrolyte concept and then co-sintered at 600°C for 1 h. For the physicochemical and electrochemical characterizations, the anode-supported composite PCFCs are investigated by various analysis tools such as XRD, SEM, electrochemical polarization, and impedance spectroscopy.

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Keywords: Protonic ceramic fuel cell (PCFC), Composite electrolyte, Yttrium-doped barium zirconate (BZY), Carbonate, Performance.

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park).