Research On LSGM Electrolyte Of Solid Oxide Fuel Cells

Taking actual environment of developing anode-supported intermediate temperature solid oxide fuel cells (IT-SOFC), this paper chooses Sr, Mg doped lanthanum gallate La1-xSrxGa1-yMgyO3-Π (LSGM) with high ionic conductivity as electrolytes and Sr, Mn doped lanthanum chromites Lai-xSrxCri-yMnyO3-δ (LSCM) with high electronic conductivity as anode supports. Different proportion LSGM powders and the influence of different synthesis methods on LSGM powders were studied for structure refinement. The growth mechanism of LSGM electrolyte film fabricated by RF magnetron sputtering method was discussed. The preparation technology of LSGM electrolyte films via RF magnetron sputtering and slurry spin coating method were optimized, respectively.Different proportion LSGM powders La0.8Sr0.2Ga0.8Mg0.203-δ (LSGM8282), La0.9Sr0.iGa0.8Mg0.203-δ (LSGM9182), La0.9Sr0.1Ga0.9Mg0.1O3-δ (LSGM9191) were synthesized by solid state reaction method. XRD of different proportion LSGM powders were studied for Rietveld structural refinement with professional software Maud. The results shows that different proportion LSGM powders have different crystal structures.The lattice structure of LSGM8282is cubic with space group pm3m; the lattice structures of LSGM9182and LSGM9191are monoclinic with space group I2/a. With different doping content of Sr, Mg, samples have different purities:LSGM8282> LSGM9182> LSGM9191. LSGM electrolyte powders with different crystal structures have different electrical conductivities. The conductivities of LSGM are higher than other samples with different proportion under600-800℃, but LSGM9182is just slightly lower than LSGM8282.The preparation method has a significant impact on crystal structure of LSGM electrolyte powders. LSGM9182powders were synthesized via glycine-nitrate process (GNP) and solid state reaction with different sintering temperature1400℃、1450℃ (SSR1400, SSR1450). LSGM powders fabricated by different preparation methods have different crystal structures. The lattice structure of LSGM9182made by GNP method is orthorhombic with space group Imma; the lattice structures of LSGM9182made by SSR1400and SSR1450are monoclinic with space group I2/a. Three kinds of samples have different purities:SSR1450>SSR1400> GNP. LSGM sample fabricated by SSR method has higher purity, and higher sintering temperature is in favor of improving pure degree. LSGM samples fabricated by SSR method has higher electrical conductivity than powders made by GNP method. Ionic conductivity of LSGM9182made by SSR1450is higher than samples made by SSR1400.In this thesis, LSGM thin electrolyte film has been successfully fabricated by RF magnetron sputtering method on LSCM anode substrate. The sputtering power, substrate temperatures, the influence of annealing on morphologies and roughness of LSGM electrolyte films were discussed to obtain the optimized process parameters, which can be put into application for constituting good SOFC systems. The results shows that the appropriate parameters to fabricate LSGM films by RF magnetron sputtering method are: sputtering power as300W, substrate temperature as250℃. Under the optimum conditions, the growth mechanism of LSGM electrolyte films fabricated by RF magnetron sputtering method was discussed, which is island-like.In addition, the LSGM thin films were successfully deposited by slurry spin coating method on LSCM porous anode substrates by changing different operating technical parameters. Terpineol’s content, ethyl cellulose’s content and coating cycles were discussed to obtain the optimized parameters which can be put into application for constituting good SOFC systems. All the results indicate that, through optimizing the three key processing factors of slurry spin coating method, the operating parameters are fixed as the content of terpilenol5wt%, content of ethyl cellulose10wt%, and the coating cycles5.