Novel n-i CeO2/a-Al2O3 Heterostructure Electrolyte Derived from the Insulator a-Al2O3 for Fuel Cells

Heterostructure technologies have been regarded as promising methods in the development of electrolytes with high ionic conductivity for low-temperature solid oxide fuel cells (LT-SOFCs). Here, a novel semiconductor/insulator (n-i) heterostructure strategy has been proposed to develop composite electrolytes for LT-SOFCs based on CeO2 and the insulator amorphous alumina (a-Al2O3). The constructed CeO2/a-Al2O3 electrolyte exhibits an ionic conductivity of up to 0.127 S cm-1, and its fuel cell achieves a maximum power density (MPD) of 1017 mW cm-2 with an open-circuit voltage (OCV) of 1.14 V at 550 degrees C without the short-circuiting problem, suggesting that the introduction of a-Al2O3 can effectively suppress the electron conduction of CeO2. It is found that the potential energy barrier at the heterointerfaces caused by the ultrawide band gap of the insulator a-Al2O3 plays an important role in restraining electron conduction. Simultaneously, the thermoelectric effect of the insulator induces more oxygen vacancies because of interface charge compensation, which further promotes ionic transport and results in high ionic conductivity and fuel cell performance. This study presents a practical n-i heterostructure electrolyte design, and further research confirmed the advanced functionality of the CeO2/a-Al2O3 electrolyte. Our study may open frontiers in the field of developing high-efficiency electrolytes of LT-SOFCs using insulating materials such as amorphous alumina.

Automated summary

A novel n-i heterostructure strategy using CeO2 and amorphous alumina has been proposed to develop composite electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs). The CeO2/a-Al2O3 electrolyte exhibits high ionic conductivity and fuel cell performance due to the suppressing effect on electron conduction and the promotion of ion transport caused by the potential energy barrier and thermoelectric effect at the heterointerface. This study presents a practical electrolyte design and opens frontiers in developing high-efficiency electrolytes for LT-SOFCs using insulating materials.