【作者】 刘丽娜；

【导师】 李箭； 池波；

【作者基本信息】 华中科技大学 ， 材料学， 2009， 硕士

【摘要】 中温固体氧化物燃料电池(IT-SOFC)是固体氧化物燃料电池发展的必然趋势。工作温度的降低有效的改善了高温固体氧化物燃料电池成本高、材料选择面窄、稳定性差等一系列问题,有效的促进固体氧化物燃料电池的商业进程。但温度的降低也使得电极的电催化活性降低,尤其是阴极。本文针对这种情况,尝试通过改进传统阴极材料La1-xSrxCo1-yFeyO3-δ(LSCF)的电极结构来提高它的性能,并探索了La1-xSrxCo1-yNiyO3-δ(LSCN)作为中温固体氧化物燃料电池(IT-SOFC)阴极材料的可能性。以葡萄糖/丙烯酰胺作为螯合剂,以相应金属离子的硝酸盐为原料,采用溶胶凝胶的方法制备出了LSCF、LSCN的粉体,并系统研究了螯合剂用量及不同螯合剂对制备工艺的影响。通过XRD物相分析证明所制备的粉体有着纯净的钙钛矿结构;SEM和TEM的分析结果则表明,此方法制备的粉体粒径极小。将不同方法制备的LSCF粉体用丝网印刷的办法,制成LSCF-YSZ的半电池,测试结果表明,该方法制备出的粉体所制备半电池的电化学性能最好。分别采用溶液注入法和丝网印刷法制备出了不同微观结构的电极。在溶液注入的方法制备半电池时,在溶液中加入表面活性剂,使得单次溶液注入的量明显提高,有效的简化了制备工艺。同时结合SEM和EIS测试,系统研究了溶液注入量和极化对半电池性能的影响。SEM分析结果表明,溶液注入法中,注入三次后,LSCF和LSCN均已经在YSZ多孔层上形成了良好的三维网络结构。而丝网印刷法的阴极也呈现出颗粒细小,微观结构良好的多孔结构。电化学测试结果表明,溶液注入法中,注入三次制备的半电池的电化学性能较好。对比丝网印刷法和溶液注入法制备半电池的电化学性能,结果表明LSCF溶液注入法的半电池性能优于丝网印刷法,而LSCN则仅在600℃到700℃的范围内,溶液注入法才更有优势。对不同方法制备的LSCF和LSCN半电池进行极化测试,发现丝网印刷法制备的半电池在极化电流作用下稳定性较好。而溶液注入法中,比较不同注入量的半电池极化性能,发现两者稳定性相差不大。用溶液注入法制备了LSCF的9cm*9cm的单电池,测试了溶液注入量、气流量及测试温度对单电池电化学性能的影响。发现随着注入量的增多和测试温度的升高,其电化学反应速度也随之加快,单电池需要通以更大的气流量以满足其性能要求。而将测试过的单电池进行二次测试结果表明,重复测试的单电池性能下降较小。更多还原

【Abstract】 Intermediate temperature solid oxide fuel cell (IT-SOFC) has been widely investigated worldwide as its cost can be reduced substantially for successful commercialization of SOFC technologies. However, to lower the operating temperature of SOFCs from the traditional 1000 to 600–800℃requires a cathode with high electrocatalytic activity. The electrochemical performance for traditional cathode material La0.8Sr0.2Co0.5Fe0.5O3-δ(LSCF) was improved by a modified of the microstructure. And the electrochemical performance of La0.8Sr0.2Co0.8Ni0.2O3-δ(LSCN) was studied, which is the alternative cathode.The cathode material of LSCF for IT-SOFC was synthesized by a facile and cost-effective sol-gel method with combining glucose and acrylamide as chelating agents. The effect of the ratio of glucose and acrylamide monomer to metal nitrates was investigated in detail. The XRD results indicated that the pure perovskite phase was obtained. SEM and TEM results reveal that the prepared particle size is in nanometer scale. LSCF powders prepared by different methods were made as half cells by screen printing method, and the cathode prepared by the powder using glucose and acrylamide as chelating agents showed high electrochemical performance.Two kinds of composite cathodes which have different electrode microstructure were prepared with YSZ electrolyte by wet impregnation method and screen printing method. In wet impregnation method, the added of surfactant effectively increased the impregnation amount of per time and efficiently simplified the wet impregnation technique. The electrode fine structure and the electrochemical performance were measured by SEM and electrochemical impedance spectra (EIS), and the effect of impregnation amount and polarization test on the electrochemical performance were studied. SEM results showed that both LSCN and LSCF half cell have good microstructure. However, LSCN particles were much larger than LSCF particles in the half cell prepared by wet impregnation method. The EIS results indicated that both LSCN and LSCF half cell have excellent performance by impregnated 3 times. Compared the half cell made with the same material by different methods, we find that LSCF prepared by screen painting method had a better electrochemical performance between 600℃and 750℃, while LSCN prepared by the same method had better results from 600℃to 700℃. The polarization test results of both LSCF and LSCN half cell revealed that screen printing method was more stable than wet impregnation method.Anode supported cells were prepared with LSCF cathode by wet impregnation method, the size of the cell is 9cm*9cm. The influence of the cathodes with different ratio of LSCF to YSZ, air flow and testing temperatures was studied. The result indicated that with the increase of the impregnated amount and testing temperature, the cell need larger air flow to satisfy the more quickly electrochemical reaction. Howerve, after polarized for 320 minutes, the performance of the cell degraded gradually.更多还原