Remarkable Ionic Conductivity in a LZO-SDC Composite for Low-Temperature Solid Oxide Fuel Cells

Abstract

Recently, appreciable ionic conduction has been frequently observed in multifunctional semiconductors, pointing out an unconventional way to develop electrolytes for solid oxide fuel cells (SOFCs). Among them, ZnO and Li-doped ZnO (LZO) have shown great potential. In this study, to further improve the electrolyte capability of LZO, a typical ionic conductor Sm0.2Ce0.8O1.9 (SDC) is introduced to form semiconductor-ionic composites with LZO. The designed LZO-SDC composites with various mass ratios are successfully demonstrated in SOFCs at low operating temperatures, exhibiting a peak power density of 713 mW cm−2 and high open circuit voltages (OCVs) of 1.04 V at 550 °C by the best-performing sample 5LZO-5SDC, which is superior to that of simplex LZO electrolyte SOFC. Our electrochemical and electrical analysis reveals that the composite samples have attained enhanced ionic conduction as compared to pure LZO and SDC, reaching a remarkable ionic conductivity of 0.16 S cm−1 at 550 °C, and shows hybrid H+/O2− conducting capability with predominant H+ conduction. Further investigation in terms of interface inspection manifests that oxygen vacancies are enriched at the hetero-interface between LZO and SDC, which gives rise to the high ionic conductivity of 5LZO-5SDC. Our study thus suggests the tremendous potentials of semiconductor ionic materials and indicates an effective way to develop fast ionic transport in electrolytes for low-temperature SOFCs.

High-performing and stable semiconductor yttrium-doped gadolinium electrolyte for low-temperature solid oxide fuel cells

“…The enhancements in the relative ratio of O a are responsible for high ionic conduction and fast HOR functionalities. 17 The Y 3d and Gd 4d deconvoluted spectra, as shown in Fig. 2b and c, well matched the reported findings in the literature.…”

Thermally Stable Silver Cathode Covered by Samaria-Doped Ceria for Low-Temperature Solid Oxide Fuel Cells

“…The obtained EIS results were fitted using an equivalent circuit model to confirm all resistors to related semicircles. The first semicircle of EIS spectra represents ohmic losses and the radius of the second semicircle denotes polarization losses [36]. A slight difference in terms of ohmic losses was observed among the fuel cells, while there was a significant variation in terms of polarization losses.…”

Advances in lithium-ion battery materials for ceramic fuel cells

“…The cell achieved a power density of 982 mW/cm 2 at 520 °C [56] . A Li-doped ZnO (LZO)/SDC electrolyte showed superionic conductivity (> 0.1 S/cm over 300 °C) without electron leakage and excellent electrolytic performance (400-630 mW/cm 2 ) was recorded between 480 and 550 °C [57] . Tu et al further revealed that a LZO/SDC composite had a hybrid H + and O 2conducting capability with predominantly H + conduction [58] .…”