Theoretical and Experimental Studies on Perovskite Materials for the Electrodes of Intermediate Temperature Solid Oxide Fuel Cells

Speaker :
Mr Tsam Lung YOU
Department of Mechanical and Aerospace Engineering, HKUST
Date : 30 Aug 2018 (Thu)
Time : 10:00 am
Venue : Room 5564, HKUST (5/F., Lift #27/28)


The growing global demand for energy and the rising level of environmental awareness lead to constantly increasing attention in the development of highly efficient, environmentally friendly and safe energy solutions. Among various energy conversion and storage devices, intermediate temperature solid oxide fuel cells (IT-SOFC) are regarded as one of the most promising candidates because of their high conversion efficiency and limited emission of pollutant. When used with renewable energy sources, the disadvantages of the energy sources such as intermittence and unpredictability can be covered. However, the sluggish catalytic activities of electrodes under intermediate temperature range is currently a bottleneck for the development of IT-SOFC. New electrode materials need to be developed and perovskite materials are widely regarded as one of the best candidates for the purpose. In this thesis, two studies on perovskite electrode materials for IT-SOFCs were carried out.

In the first study, we built a 1D ion transportation model to study the effect of Ba segregation in Ba0.95La0.05FeO3-δ (BLF), a cathode material for IT-SOFC, in both bulk material case and thin film case. Besides the Poisson-Nernst-Planck system, the model also considers the effects of concentration gradients, size misfit and Vegard stress. The model was able to reproduce the experimental results previously done by our group. In addition, we suggested a novel mechanism explaining suppression of ion segregation in pre-strained thin films using theories of dislocation.

In the second study, we investigated exsolution of Ni nanoparticles by electrochemical poling on Ni and La co-doped CaTiO3 (LCTN) which is an anode material for IT-SOFC. By applying potential bias, we successfully exsolve nanoparticles on the surfaces of LCTN in as short as a few minutes, which is up to a hundred times lower than the time required for exsolution under a reducing atmosphere. We observed two types of nanoparticles after exsolution, one with irregular, worm-like shape and another one with spherical shape. This work deepens our understanding in the formation of nanoparticles in exsolution.

(Supervisor: Prof. Francesco Ciucci)