Banca de QUALIFICAÇÃO: MORENA BRITO DE FARIAS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MORENA BRITO DE FARIAS
DATE: 03/05/2024
TIME: 09:00
LOCAL: https://videoconf-colibri.zoom.us/j/98520959245
TITLE:

Study of cobalt-free composite electrodes for solid oxide fuel cells

KEY WORDS:

Solid Oxide Fuel Cell (SOFC); Electrochemical Impedance Spectroscopy (EIS); Mixed Ionic-Electronic Conductor (MIEC); Double perovskite, Ruddlesden-Popper phases.

PAGES: 91
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

Oxides are materials that, depending on their structure and chemical composition, can
demonstrate promising results for electrochemical applications in fuel cells. In this context, the
cathodes of these devices play a crucial role, often significantly limiting the overall kinetics of
electrochemical conversion. Traditionally, materials containing cobalt are widely used as
cathodes due to their excellent kinetics for reactions with oxygen. However, one of the current
challenges is to replace this critical element in energy applications due to concerns related to
health, the environment, and limited geographic availability. In this thesis, the compounds
Sr2Fe1.5Mo0.5O6-δ (SFM) and Lan+1NinO3n+1 (n = 1 and 3, LNO) are explored as cobalt-free
cathodes for solid oxide fuel cells, demonstrating excellent mixed ionic-electronic conduction
properties. The electrodes were initially optimized by successive deposition of material layers
onto the electrolyte substrate, resulting in a higher solid fraction near the electrode/electrolyte
interface. This process not only optimized the thickness of the electrodes but also improved
the distribution of ionic current from the electrolyte into the electrode, resulting in a reduction
in polarization resistance. Additionally, the study included the formation of a new composite
electrode of SFM with approximately 34 vol% of Ce0.8Pr0.2O2-δ, resulting in improvements in the
incorporation kinetics. However, the overall performance of this composite electrode was
compromised by insufficient electronic conductivity. For the LNO electrodes, impregnation
with praseodymium oxide (~10 wt%) was performed. The study reveals a reduction in
polarization resistance by 7 and 20 times for La2NiO4+δ and La4Ni3O10-δ, respectively (at 700 °C).
Therefore, this work provides important insights into the microstructural and compositional
criteria for the future development of cathodes.

COMMITTEE MEMBERS:
Presidente - 1300987 - CARLOS ALBERTO PASKOCIMAS
Interno - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo à Instituição - ALLAN JEDSON MENEZES DE ARAÚJO - UA
Externo à Instituição - FRANCISCO JOSÉ ALMEIDA LOUREIRO - UA