Sintering-induced cation displacement in protonic ceramics and way for its suppression.

Liu, Ze; Song, Yufei; Xiong, Xiaolu; Zhang, Yuxuan; Cui, Jingzeng; Zhu, Jianqiu; Li, Lili; Zhou, Jing et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Protonic ceramic fuel cells with high efficiency and low emissions exhibit high potential as next-generation sustainable energy systems. However, the practical proton conductivity of protonic ceramic electrolytes is still not satisfied due to poor membrane sintering. Here, we show that the dynamic displacement of Y<sup>3+</sup> adversely affects the high-temperature membrane sintering of the benchmark protonic electrolyte BaZr<sub>0.1</sub>Ce<sub>0.7</sub>Y<sub>0.1</sub>Yb<sub>0.1</sub>O<sub>3-δ</sub>, reducing its conductivity and stability. By introducing a molten salt approach, pre-doping of Y<sup>3+</sup> into A-site is realized at reduced synthesis temperature, thus suppressing its further displacement during high-temperature sintering, consequently enhancing the membrane densification and improving the conductivity and stability. The anode-supported single cell exhibits a power density of 663 mW cm<sup>-2</sup> at 600 °C and long-term stability for over 2000 h with negligible performance degradation. This study sheds light on protonic membrane sintering while offering an alternative strategy for protonic ceramic fuel cells development.