| Lanthanum gallate doped with strontium and magnesium (LSGM) is a promising electrolyte system for intermediate temperature solid oxide fuel cells (SOFCs). The preparation method of the powder has been studied, but it isn't mature for fabrication of the thin film. Tape castig has the advatages of a low cost,short produce cycle,high output,stabilized capability and so on. In this paper, LaGaO3 (LSGM) electrolyte thin film was prepared by the method of non-aqueous tape casting.The preparation techonology of the LSGM powders by a solid reaction method was discussed and the optimum sintering procedure was decided. The best LSGM powders 3.04μm in diameter were obtained by being sintered at 900℃for 24h and at 1300℃for 36h and this preparation technology has attained the advanced international level. Then, the best slurry composition, which was decided by precipitation and viscocity test, contains 80g LSGM powders, 60mL butanone/ethanol (60/40) as the solvent, 2mL triethanolamine as the dipersant and 6.4g polyvinyl butyral as the binder and 3.2g/4mL polyethylene glycol/diethyl phthalate as the plasticizer.The macroscopically smooth and homogeneous LSGM electrolyte base of 5×5cm in size was obtained by sintering the green tape at 1500℃for 6 h. The thus prepared LSGM electrolyte base possesses a relative density of 96.0%, a porosity of 0.38% and good compatiblitty with the BCAS551 glass-ceramic sealing materials, which ensures the structure stability of the cell within the operating temperature. Electrochemistry impedance spectrum test revealed that the conductivity of LSGM electrolyte was primarily controlled by conductivity of the grain boundary within the low temperature range and the conductivity of the grain within the high temperature range. The conductivity activation energy was 0.93eV within the high temperature range, which is higher than the conductivity activation energy of 0.64eV at the temperature above 873K. The conductivity of the LSGM electrolyte was 0.082S·cm-1 at 1073K.Finally,the thermal compatibility between all the components of the cell was studied and the cell has a maximum power density of 0.33W·cm-2 and an OCV of 1.073V at 800℃, which is comparable to the theoretical value of 1.2V. |
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