THESIS
2018
x, 81, that is, xi, 81 pages : illustrations ; 30 cm
Abstract
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 de...[
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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
Ba
0.95La
0.05FeO
3-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 CaTiO
3 (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.
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