Since colossal ionic conductivity was detected in the planar heterostructures consisting of fluorite and perovskite, heterostructures have drawn great research interest as potential electrolytes for solid oxide fuel cells (SOFCs). However, so far, the practical uses of such promising material have failed to materialize in SOFCs due to the short circuit risk caused by SrTiO₃. In this study, a series of fluorite/perovskite heterostructures made of Sm-doped CeO₂ and SrTiO₃ (SDC–STO) are developed in a new bulk-heterostructure form and evaluated as electrolytes. The prepared cells exhibit a peak power density of 892 mW cm⁻² along with open circuit voltage of 1.1 V at 550 °C for the optimal composition of 4SDC–6STO. Further electrical studies reveal a high ionic conductivity of 0.05–0.14 S cm⁻¹ at 450–550 °C, which shows remarkable enhancement compared to that of simplex SDC. Via AC impedance analysis, it has been shown that the small grain-boundary and electrode polarization resistances play the major roles in resulting in the superior performance. Furthermore, a Schottky junction effect is proposed by considering the work functions and electronic affinities to interpret the avoidance of short circuit in the SDC–STO cell. Our findings thus indicate a new insight to design electrolytes for low-temperature SOFCs.

由于在由萤石和钙钛矿组成的平面异质结构中检测到巨大的离子电导率，异质结构作为固体氧化物燃料电池（SOFC）的潜在电解质引起了极大的研究兴趣。然而，到目前为止，由于由SrTiO ₃引起的短路风险，这种有前途的材料的实际用途未能在SOFC中实现。在这项研究中，以Sm掺杂的CeO ₂和SrTiO ₃（SDC–STO）制成的一系列萤石/钙钛矿异质结构以新的本体异质结构形式开发，并作为电解质进行了评估。制备的电池表现出892 mW cm ^-2的峰值功率密度550°C时的开路电压为1.1 V，以实现4SDC–6STO的最佳组成。进一步的电学研究表明，在450-550°C时具有0.05-0.14 S cm ^-1的高离子电导率，与单纯形SDC相比，离子电导率显着提高。通过交流阻抗分析，已显示出小的晶界电阻和电极极化电阻在导致优异性能方面起着主要作用。此外，通过考虑功函数和电子亲和力提出了肖特基结效应，以解释避免SDC-STO电池发生短路的情况。因此，我们的发现为设计用于低温SOFC的电解质提供了新的见识。