S.A. Muhammed Ali

Optical, mechanical and electrical properties of LSCF–SDC composite cathode prepared by sol–gel assisted rotary evaporation technique

AbstractLa0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) is a perovskite-type oxide that exhibits excellent mixed ionic–electronic conducting properties and is a suitable cathode material for intermediate temperature solid oxide fuel cells. This study investigates the microstructural, optical, mechanical, and electrical properties of an LSCF–samarium-doped ceria (SDC) composite cathode. LSCF–SDC composite cathode powders were prepared by mixing 50 wt% SDC electrolyte with LSCF cathode powders obtained by the rotary evaporation technique. The band gap of the prepared powders was determined via diffuse reflectance UV–visible spectroscopy. The chemical composition, mechanical properties, and electrochemical properties of the sintered pellets were characterized using Raman spectroscopy, Vickers hardness, and impedance spectroscopy, respectively. X-ray diffraction and Rietveld analysis showed that phase purity was only 96%. Moreover, a small fraction of tetragonal phase impurity was observed on the LSCF powders. Impurities significantly affected the phase stability and microstructure of the LSCF–SDC composite cathode. The addition of the SDC electrolyte enhanced the densification of the composite cathode, thereby improving mechanical properties. However, the addition of SDC exerted different effects on the DC electrical conductivity and area-specific resistance (ASR) of the composite cathode. At 800 °C, the ASR value of the LSCF was only 2% that of the LSCF–SDC composite cathode. Overall, the electrical properties of the LSCF–SDC composite cathode are closely related to the crystal structure, purity, and microstructure of LSCF cathode powders.

A review on preparation of SDC-carbonate as composite electrolyte material for intermediate temperature Solid Oxide Fuel Cells (IT-SOFC)

Solid Oxide Fuel Cells (SOFCs) is a promising technology with unique characteristics to generate electricity by combining fuel and oxygen ions in an electrochemical reaction. However, ceramic based fuel cells generally operate at high temperatures above 800°C. Recent researches have given much improvement in reducing the temperature and lowering the manufacturing costs by developing new materials to commercialize SOFCs. The overall performance of the cell depends on each component in the cell. Composite electrolytes based on a mixture of samarium-doped ceria (SDC)-carbonate is the most commonly used electrolyte for SOFCs operating at low temperatures. High conductivity and electrical insulation are the two important needs for an electrolyte to yield better performance based on the purity of prepared SDC powders. This paper reviews several different methods for preparing pure SDC powders. The advantages and disadvantages of each method and its electrical chemical performance at low temperature are discussed.