Influence of Silver Addition on the Morphological and Thermal Characteristics of Nickel Oxide-Samarium Doped Ceria Carbonate (NiO-SDCC) Composite Anode

Abstract

Addition of silver (Ag) as an electro-catalyst has been widely investigated to enhance the cathode performance for intermediate-to-low temperature solid oxide fuel cells. Ag is seldom incorporated into composite anode materials, especially for low temperature application. Therefore, this study aimed to investigate the effects of a small amount of Ag on the microstructure and thermal behaviour of nickel oxidesamarium-doped ceria carbonate (NiOSDCC) composite pellets. A high-speed ball milling technique was employed to prepare the NiOSDCC composite anode powder. Subsequently, a small amount of Ag (1, 3, and 5 wt.%) was added into NiOSDCC composite powder via ball milling. The pellets were manually pressed and sintered at 600 °C. Characterisation of the composite anodes included X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy, scanning electron microscopy, dilatometry and porosity measurement. NiOSDCC maintained good chemical compatibility regardless of Ag loading. FTIR analysis also verified the presence of carbonates, suggesting that Ag did not influence the carbonate bonding in all NiOSDCC. The porosity of all composite anodes was maintained within the satisfactory level for good anode performance (20%40%). The thermal expansion of the composite samples matched well with the SDCC electrolyte. This finding indicated that the addition of small Ag loading into NiOSDCC was within the acceptable range, demonstrating promising potential as low-temperature solid oxide fuel cell composite anode.

A review on the preparation of anode materials and anode films for solid oxide fuel cell applications

“…The advantages of the sol-gel method are enumerated as follows. 20,39,111 • Controls the processing parameters, such as the precursor materials and complexing agent • Eliminates long diffusion paths, impurities, and agglomeration • Produces high-purity and ultrafine powders high-temperature superconductors, ferrites, and manganites.…”

“…The overall stoichiometry of the required materials is illustrated in Figure 5. The advantages of the sol‐gel method are enumerated as follows 20,39,111 Controls the processing parameters, such as the precursor materials and complexing agent Eliminates long diffusion paths, impurities, and agglomeration Produces high‐purity and ultrafine powders Requires inexpensive equipment Facilitates the low‐temperature development of the material Performs rapid deposition Possesses low sintering temperature Produces high‐grade materials for the fabrication of thin electrolyte membrane and electrode Possesses no limitation in the shape or size of the substrate surface …”

“…The TEC value difference between the electrolyte and anode should range within 15% to 20% to avoid thermal stresses and mechanical failure at high operating temperatures. 20 The suitable materials should be determined to overcome such issues. The redox instability, which is reflected in microstructural changes, can be addressed by modifying the microstructure of the anode.…”

“…To avoid TEC mismatch and cracking issues, the value of the former between two neighboring components or electrodes should be as close to each other. The TEC value difference between the electrolyte and anode should range within 15% to 20% to avoid thermal stresses and mechanical failure at high operating temperatures 20 . The suitable materials should be determined to overcome such issues.…”

Understanding the Impact of Sintering Temperature on the Properties of Ni–BCZY Composite Anode for Protonic Ceramic Fuel Cell Application

“…Hence, its properties are very critical in any operating condition. In this regard, the anode requires a material with a small mismatch in thermal expansion coefficient (TEC) with the electrolyte components (15-20%) to avoid micro cracks and delamination problems [3]. In addition, the anode must have sufficient porosity (20-40%) for hydrogen, water vapour and electron transfer [4].…”