Improvement of Cathode Material for Solid Oxide Fuel Cell through Surface Infiltration and Electrospinning

In this study, two methods have been used to enhance the catalytic property of the La_0.6Sr_0.4Co_0.2Fe_0.8O₃/Ce_0.9Gd_0.1O₂ (LSCF/CGO; LSCF:CGO = 1:1) cathode in solid oxide fuel cell applications. One method involved altering the surface of the LSCF/CGO by including metal oxide nanoparticles. By utilizing an infiltration approach, Co₃O₄, NiO and CuO nanoparticles with a particle size of 10–20 nm has been effectively deposited onto the surface of the LSCF/CGO composite cathode. The as infiltrated cathode showed significant reduction in the overall area-specific resistance (ASR) at 500^oC (1.72Ω•cm², 2.5Ω•cm², and 3.9Ω•cm² respectively), which was nearly 4-10 times smaller than the non-infiltrated LSCF/CGO (15.5Ω•cm²) at 500^oC. The enhanced electro-catalytic active sites that these nano decorations on the cathode's surface can provide were ascribed to this improvement. It was discovered that these metal oxides increased the density of reaction sites on the surface, encouraging improved surface oxygen ion exchange sites at the interface between the basic cathode materials and the catalytic oxides. The oxygen ions supplied by these metal oxides assisted in reducing the oxygen vacancy concentration on the surface of LSCF and suppressing the Sr surface segregation, which was verified by SEM and XPS, therefore slowing the pace of cell performance degradation. Impedance experiments utilizing symmetrical cells, where the performance degradation rate of LSCF/CGO at 500^oC dramatically decreased because of Co₃O₄, NiO, and CuO nanoparticles metal oxide infiltration, verified the cathode's performance. In this work, it has also been recognized how the silver particles on the LSCF/CGO surface affect the cell's overall catalytic properties. The silver current collector was also discovered to be partially responsible for the decline in cell function with age. By infiltrating Co₃O₄ nanoparticles into both the silver current collector and the LSCF/CGO, the cell degradation rate declined from 1.78 Ω•cm²/hour to 0.06 Ω•cm²/hour at 500^oC. In a different method, an electro-spun cathode was employed in place of a conventional powder-formed cathode. This cathode had a fibrous structure. By meticulously regulating the electrospinning parameters, such as voltage, solution concentration, and the distance between the needle and the collector, the method of creating nanofibres has been researched and perfected. By coating the electrolyte with uniform CGO fibres covered with LSCF nanoparticles, a cathode was created. The fibrous cathode demonstrated much reduced ASR (about 5 times smaller) than the powder-formed cathode in the temperature range of 500^oC to 650^oC. It has also been researched and adjusted how the loading of LSCF affects CGO fibre. The quantity of LSCF has been proposed by modeling and experimental evidence.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2017

Author dc:creator

• Gao, Chenlong

Advisor dc:contributor.advisor

• Kumar, Ramachandran

• Cathode
• electrospinning
• SOFC

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/e56014ab-998e-4b97-a2f1-03fad8edf166/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.102255

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/358831