Research Based On The Ca₃Co₄O₉Thermoelectric Cathode Materials Of Solid Oxide Fuel Cells

At present, to solve the energy problem and environmental problems these two urgentcrisis, the most important thing is using the existing fossil energy sources more effective,reducing CO₂production and emission. Under this background, to find and develop newenergy solutions to replace the fossil energy has become important topics for all over theworld to explore. Electrochemical power source as a highly efficient energy conversionand storage devices, has received the widespread attention and in-depth research. Fuel cellas a kind of modern chemical power source, can continuously convert chemical energyinto electrical energy and its working principle is completely different from traditionalbattery. As long as there is a steady stream of fuel and oxygen, it can continuously producepower, more similar to the generator instead of batteries. Fuel cells because of its highefficiency, no pollution, no noise, environment friendly, large e nergy density, in thedevelopment of clean energy will play an important role in the process.Taking Ca₃Co₄O₉thermoelectric cathode materials for the research object, we studythermoelectric cathode materials which can use the waste heat generated from solid oxidefuel cells work to further improve the fuel cell energy utilization. Through a series of testswas taken to prove that this material has good catalytic activity, and the compatibility withelectrolyte has increased significantly.Ca₃Co₄O₉as conventional fuel cell cathode material has been test of the singlebattery power density. The power density under condition of the H₂as fuel and air asoxidizer in800and750℃is respectively779and581mW/cm2. Ca₃Co₄O₉as fuel cellcathode material testing the thermoelectric voltage, found that the thermoelectric voltageis10.2mV. Thermoelectric cathode material can take advantage of the excess heatgenerated in the fuel cells work. Between100and800℃Ca₃Co₄O₉has a TEC about（6-12） x10-6k-1, which is very close to LSGM electrolyte TEC （10-13） x10-6k-1.Use stretch film laminated method to get a self-supporting electrolyte thin film ofsolid oxide fuel cell and the thickness of dense electrolyte layer is about10to15microns.we get a battery by impregnation, including Ca₃Co₄O₉cathode and the NiO anode. In power density test of the battery, we found that the open circuit voltage is close to thetheoretical voltage. The electrolyte has densification and isolation of two gases. Thepower density in700,650and600℃is respectively640,500and420mW/cm2. Afterimpregnation, cathode has become continuous nano particles. Although this structureprovided the greater interface for the catalytic reaction of, greatly improved the cathodeohm impedance, hinder the further improve of the battery performance.