Advances in novel SDC@Al₂O₃ core−shell electrolyte for low‐temperature solid oxide fuel cell

Abstract

The preparation of electrolyte with excellent ionic conduction is an important development direction in the practical application of solid oxide fuel cell (SOFC). Traditional methods to improve ion conduction was structure doping to develop electrolyte materials. In this work, the ionic conductor Ce0.8Sm0.2O2‐δ (SDC) was modified by insulator Al2O3 to enhance ion conduction and apply as electrolytes for the SOFC. The transmission electron microscopy (TEM) characterization clearly clarified that a thin Al2O3 layer in the amorphous state coated on SDC to form the SDC@Al2O3 core−shell structure. The SDC@Al2O3 electrolyte with the core−shell structure possesses a super ionic conductivity of 0.096 S cm−1 and results in advanced cell performance of 1190 mW cm−2 at 550°C. The X‐ray photoelectron spectroscopy (XPS) analysis revealed that the concentration of oxygen vacancies in the SDC@Al2O3 core–shell structure significantly improved in comparison with pure SDC, the newly produced oxygen vacancies can promote the oxygen ion transport. Moreover, the interface between SDC and Al2O3 provides a fast channel for the proton transport. In addition, the SDC‐based SOFC was usually suffered from the reduction of the SDC electrolyte and the accompanying generated electron conduction should deteriorate the cell performance, this is the main challenge for the SDC electrolyte application. In our case, the Al2O3 shell on the SDC surface not only can avoid the contact between SDC and hydrogen to eliminate the reduction of SDC but also can restrain electron conduction due to the electron insulation characteristic of the Al2O3 shell. This work demonstrates an efficient approach to develop the advanced low‐temperature SOFC technology from material fundamentals.

Interlayer Conducting Mechanism in α-LiAlO2 Enables Fast Proton Transport with Low Activation Energy for Solid Oxide Fuel Cells

“…33 A detailed description of H/D isotope experiments can be found in our previous reports. 34 The dissolution of gaseous H 2 O and D 2 O will produce the amount of H + and D + in the electrolyte, and if the electrolyte can conduct protons, the different diffusion rates of H + and D + will be directly reflected in the impedance spectrum. 35,36 Figure 3a Table 2.…”

High-Performance Low-Temperature Solid Oxide Fuel Cell with a Pt@C–Ni0.8Co0.15Al0.05LiO2−δ Composite Cathode

“…There were also many studies on excellent electrolytes for low-temperature SOFCs, Deng et al studied a hybrid ion/electron conductor material CaSnO 3 –ZnO, such that the heterostructure had an ionic conductivity of up to 0.16 S cm –1 at 550 °C and the p–n heterojunction at the interface was able to effectively suppress the current and enhance ionic conduction. Zhou et al used an Al 2 O 3 insulator material coated with a Ce 0.8 Sm 0.2 O 2−δ ionic conductor material to enhance ionic conduction and serve as an electrolyte for SOFCs, with a conductivity of 0.096 S cm –1 at 550 °C and a power density of up to 1190 mW cm –2 . Zhu et al found that doping a small amount of Al into SrTiO 3−δ (STO) could adjust its energy band structure, thereby triggering the electrochemical mechanism and fuel cell performance and that Ni–NCAL/Al–STO/Ni–NCAL achieved an ionic conductivity of up to 0.153 S cm –1 at 520 °C and exhibited a high power density of 0.692 mW cm –2 .…”

“…There were also many studies on excellent electrolytes for lowtemperature SOFCs, Deng et al 8 studied a hybrid ion/electron conductor material CaSnO 3 −ZnO, such that the heterostructure had an ionic conductivity of up to 0.16 S cm −1 at 550 °C and the p−n heterojunction at the interface was able to effectively suppress the current and enhance ionic conduction. Zhou et al 9 used an Al 2 O 3 insulator material coated with a Ce 0.8 Sm 0.2 O 2−δ ionic conductor material to enhance ionic conduction and serve as an electrolyte for SOFCs, with a conductivity of 0.096 S cm −1 at 550 °C and a power density of up to 1190 mW cm −2 . Zhu et al 10 In our previous study, Qian et al 13 pressed symmetric fuel cells with electrodes of NCAL and a SDC electrolyte in the mass ratio of SDC/NCAL = 7:3, and the peak power densities of hydrogen and ammonia at 550 °C were 895 and 755 mW cm −2 , respectively.…”

Realizing Coinstantaneous Multiple Benefits Generation from Sm0.075Nd0.075Ce0.85O2−δ/Al2O3 Heterostructure Electrolyte by Interfacial Engineering

“…Simultaneously, i-Al 2 O 3 material exhibits high mechanical strength, chemical corrosion resistance, high-temperature insulation resistance, and good thermal conductivity . Some examples of using i-Al 2 O 3 material in SOFCs include: Cui et al demonstrated that amorphous Al 2 O 3 -2SiO 2 material reached an ionic conductivity of 1.5 × 10 –6 S·cm –1 at room temperature (RT); Xiang et al fabricated semiconductor heterostructure SDC-Al 2 O 3 electrolyte material with the core–shell structure yielding an ionic conductivity of 0.096 S·cm –1 and power density of 1190 mW·cm –2 at 550 °C. And, Zheng et al reported a ZnO–Al 2 O 3 –NiO p–i–n semiconductor heterostructure material and used it as the electrolyte of the SOFC, which gave a power density of 917 mW·cm –2 and high ionic conductivity of 0.24 S·cm –1 at 550 °C.…”