Developing Ceria-Based Nanocomposite Materials for Low/Intermediate- Temperature Solid Oxide Fuel Cells
Creators: name: Ghaemi, Nasrin
Publisher: name: University of Surrey
Year: 2024

description: Solid oxide fuel cell (SOFC) is considered a promising technology for energy conversion within the various type of fuel cell (FC) family due to several advantages including environmental friendliness (when running on pure hydrogen, the SOFC generates electricity and heat without any carbon emissions), use of non-noble materials, relatively cheap (in bulk), and fuel flexibility. Conventional SOFC operates at a temperature higher than 700-1000 °C, which increases capital expenses, limits the selection of materials, and raises component compatibility issues. The goal of recent SOFC research is to reduce the operating temperature to lower than 600-700 °C or below to make this technology more reliable for commercialisation. Developing novel electrolytes and electrode materials are considered the key strategy for lowering the SOFC's operating temperature. Meanwhile, semiconductor-ionic materials based on semiconductors (perovskite/composite) and ionic materials (e.g., ceria-based ion conductors) have been found as prospective candidates for low operating temperature SOFC, which provide an appropriate power output.<br>
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description: This study focuses on the development of a green co-precipitation method to synthesize nano- crystalline Gadolinium doped Ceria (GDC) and anode materials for low and intermediate-temperature SOFC (LT-SOFC/IT-SOFC). The GDC nano-powders synthesised through this method are unique in the way to have a sintering temperature below 1000 °C, which is essential on a commercial scale. In this work, Ni-Fe/GDC and Co-Fe/GDC with various ratios of metallic components were synthesised using the co-precipitation method. Other works have been done in this report to lower the sintering temperature of GDC and improve the ionic conductivity of the electrolyte such as the addition of additives and fabrication of by-layer electrolyte, which can be summarised as follows:<br>
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description: A bilayer of GDC/YSZ was successfully fabricated using a cost-effective method, which requires further study to be established. Additionally, the effect of K2SnO3 and V2O5 as additives was studied to decrease the sintering temperature, densification, and so the ionic conductivity of the GDC.<br>
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description: The synthesised materials and fabricated cells are characterised and studied using established electrochemical and analytical methods such as x-ray powder diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), thermogravimetric analysis (TGA), pycnometer, BET specific surface area, Fourier-transform infrared spectroscopy (FTIR), Raman, Electrochemical impedance spectroscopy (EIS) and performance tests (I-V and I-P curves).<br>
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description: The synthesised nano-particles GDC (sintered at 950°C) show successful densification of 97.48 and 98.43% and electrical conductivity of 3.83 × 10− 2 and 5.90 × 10−2 S cm− 1 at 750°C for GDCW and GDCNW samples, respectively. The study of mechanical stability of synthesised GDC in various calcination and
description: sintering temperatures shows 400°C, and 1100 °C as the best calcination and sintering temperatures respectively.<br>
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description: Synthesised nanocrystalline Co-Fe/GDC and Ni-Fe/GDC were characterised and electrochemical characterisation of the products shows high catalytic activity of the synthesised bimetal/GDC compositions. The electrochemical performance of the electrolyte and electrode supported cell and their microstructures have been also investigated. Maximum power densities from 132 mW/cm2 up to 147 mW/cm2 have been achieved at 750°C for the Ni-Fe/GDC. The power density of 64.38, 123.76, 152.95, and 193.95 mW/cm2 at 450, 550, 650, and 750°C respectively was observed for the Co- Fe/GDCǀGDCǀLSCF/GDC.<br>
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description: The addition of 5% and 10% of V2O5 and K2SnO3, respectively, show an improvement in the sintering temperature and densification of the final product.<br>