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

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(3+) adversely affects the high-temperature membrane sintering of the benchmark protonic electrolyte BaZr(0.1)Ce(0.7)Y(0.1)Yb(0.1)O(3-δ), reducing its conductivity and stability. By introducing a molten salt approach, pre-doping of Y(3+) 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(-2) 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.