Crystalline Structure and Microstructural Characteristics of the Cathode/Electrolyte Solid Oxide Half-Cells

Abstract

The solid oxide fuel cell (SOFC) is an electrochemical device generating of electric energy, constituted of cathode, electrolyte and anode; that together they form a unity cell. The study of the solid oxide half-cells consisting of cathode and electrolyte it is very important, in way that is the responsible interface for the reduction reaction of the oxygen. These half-cells are ceramic materials constituted of strontium-doped lanthanum manganite (LSM) for the cathode and yttria-stabilized zirconia (YSZ) for the electrolyte. In this work, two solid oxide half-cells have been manufactured, one constituted of LSM cathode thin film on YSZ electrolyte substrate (LSM - YSZ half-cell), and another constituted of LSM cathode and LSM/YSZ composite cathode thin films on YSZ electrolyte substrate (LSM - LSM/YSZ - YSZ half cell). The cathode/electrolyte solid oxide half-cells were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results have been presented with good adherence between cathode and electrolyte and, LSM and YSZ phases were identified.

Forming of Cathodic Ceramic Film Using Airbrush for Application in High Temperature Solid Oxide Fuel Cells

“…The surface of the sintered YSZ cylindrical pellet was sandpapered and washing with ethanol for surface cleanness. This superficial treatment in the substrate caused grooves, for a better adherence of the deposited layers for formation of the LSM cathodic ceramic films [12].…”

“…This organic suspension was fed to the equipment double action manual airbrush (Lince, model AL3), whose spraying is carried through with suspension feeding by gravity and air compressor (Schulz, model Twister). When air if mixes to the suspension is formed a unique and homogeneous spurt expelled by the airbrush nozzle as a mist that must be directed to the substrate to be sprayed [8,[10][11][12][13][14].…”

“…For the formation of the LSM ceramic film was established depositions in 4 different directions of the airbrush in relation to the plan (horizontal, vertical, right and left diagonal) with drying intermediate stages for to get the desired thickness in the band of micrometers. The conformed LSM cathodic ceramic film was submitted to the drying and sintering at temperature of 1200 °C for 2 hours [12]. In Figure 2 is presented an esquematization of the distance between the airbrush nozzle and the substrate and the different directions applied for the formation of each layer.…”

Characterization of LSCF-Based Composite and LSCF as Cathodes for Intermediate Temperature SOFCs

“…However, decreasing the operating temperature reduces both electrolyte conductivity and electrode kinetics; hence the cell performance is hindered in these temperatures. To reduce the increase in electrolyte resistance due to decreasing operating temperature, it is a common practice to decrease the thickness of yttria-stabilized zirconia (YSZ) electrolyte [1][2][3][4][5] and/or to source for high ionic conducting electrolyte materials such as doped lanthanum gallate [2][3][4][5][6][7] or doped ceria [6,7,8]. Besides, to develop high performance ITSOFCs, it is desirable to design with low polarization resistance operating in these temperatures [5][6][7].…”

“…Due to its high electronic and ionic conductivities as well as high catalytic activities for oxygen reduction [3][4][5][6], mixed ionic-electronic conductor (La 1-x Sr x )(Co y Fe 1-y )O 3-δ -LSCF has been considered to be one of most promising cathode materials for intermediate or low temperature SOFCs, especially with ceria based electrolyte. One of the commonly used methods to improve cathode performance is to add an ionic ally conducting second phase, such as YSZ [1,4] or ceria based electrolyte [1,3,6,7] into the electronically conducting electrode material, typically LSCF.…”