| A fuel cell is an energy conversion device with a high efficiency and a low pollution. Different from the traditional cells that can only reserve energy, it generates electricity from fuels such as hydrogen, natural gas and other hydrocarbons. The fuel cell is also called a cell because it is composed of electrolyte, anode and cathode, which are the same for a normal cell. The electrolyte is sandwiched by the two electrodes. The fuel cell is also different from the traditional power generation methods. Because it is not limited by the Carnot cycle, fuel cell has advantages of higher energy conversion efficiency and lower polluted gases emission over the traditional generator. Recently with the natural resource exhaustion and environment deterioration, developing efficient and environmental friendly energy techniques is necessary. Since fuel cell just matches such requirements, it attracts the interests all over the world. As the fourth generation fuel cell, SOFC (Solid Oxide Fuel Cell) has many outstanding advantages, which is better than other fuel cells. Firstly, equipped with all solid components, it eliminates the problems that liquid electrolyte fuel cell faces, such as corrosion and leakage of liquid electrolytes. Secondly, operating at high temperatures, its electrode reaction is so fast that it is unnecessary to use noble metals as electrodes. Thus the cost of the cells can be minimized. At the same time, the high quality heat it emits can be fully used. The overall energy conversion efficiency of the thermal-electric system can be added up to 80%. The most outstanding advantage of SOFC is that it uses a large scale of fuels, from the hydrogen, carbon monoxide to the natural gas or even other combustive gases. Currently the main difficulty that the SOFC faces is the problem caused by high temperature and the ceramic components'match. During a SOFC working, the electrolyte and the electrodes have a waste of the power output. The waste will cut down the efficiency of the conversion, which should be avoided. As the key component of SOFC, cathode plays a very important role in the performance of the whole cell. The cathode material's properties and the cathodic microstructure are determined by the cathodic reaction mechanism. To improve the cathode performance, proper materials should be selected while perfect preparation technique should be employed at the same time. In this thesis, we focused on the cathode material's properties and the cathode preparation techniques. New electrode materials that different from traditional ones was synthesized and investigated. First, The cathode material La1-XSrXCuO3-δ(x=0.15,0.2,0.3,0.4)was synthesized by a sol-gel method. We studied their physical properties such as crystal structure, oxygen stoichiometry, electrical conductivity, cathodic polarization and single cell performance. Their the electrical properties of La1-XSrXCuO3-δcathode material were compared with La0.6Sr0.4CoO3-δ. The results show that La0.7Sr0.3CuO3-δhas better electrochemical properties. The same results were also obtained by which La0.7Sr0.3CuO3-δbased on SDC-YSZ composite electrolyte At present, in order to improve the cathode performance, electrolyte is always employed into the cathode material to form composite cathode. More... |
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