Study on zinc oxide-based electrolytes in low-temperature solid oxide fuel cells
journal contributionposted on 09.01.2018, 10:01 by Chen Xia, Zheng Qiao, Chu Feng, Jung-Sik Kim, Baoyuan Wang, Bin Zhu
Semiconducting-ionic conductors have been recently described as excellent electrolyte membranes for low-temperature operation solid oxide fuel cells (LT-SOFCs). In the present work, two new functional materials based on zinc oxide (ZnO)—a legacy material in semiconductors but exceptionally novel to solid state ionics—are developed as membranes in SOFCs for the first time. The proposed ZnO and ZnO-LCP (La/Pr doped CeO2) electrolytes are respectively sandwiched between two Ni0.8Co0.15Al0.05Li-oxide (NCAL) electrodes to construct fuel cell devices. The assembled ZnO fuel cell demonstrates encouraging power outputs of 158–482 mW cm-2 and high open circuit voltages (OCVs) of 1–1.06 V at 450–550 °C, while the ZnO-LCP cell delivers significantly enhanced performance with maximum power density of 864 mW cm-2 and OCV of 1.07 V at 550 °C. The conductive properties of the materials are investigated. As a consequence, the ZnO electrolyte and ZnO-LCP composite exhibit extraordinary ionic conductivities of 0.09 and 0.156 S cm-1 at 550 °C, respectively, and the proton conductive behavior of ZnO is verified. Furthermore, performance enhancement of the ZnO-LCP cell is studied by electrochemical impedance spectroscopy (EIS), which is found to be as a result of the significantly reduced grain boundary and electrode polarization resistances. These findings indicate that ZnO is a highly promising alternative semiconducting-ionic membrane to replace the electrolyte materials for advanced LT-SOFCs, which in turn provides a new strategic pathway for the future development of electrolytes.
This work was supported by the National Natural Science Foundation of China (Grant No. 51502084 and 51372075), the Natural Science Foundation of Hubei Province (Grant No. 2015CFA120), the Swedish Research Council (Grant No. 621-2011-4983), and the European Commission FP7 TriSOFC-project (Grant No. 303454).
- Aeronautical, Automotive, Chemical and Materials Engineering
- Aeronautical and Automotive Engineering