钙钛矿基氧化物材料的制备及电化学性能研究

发布时间：2018-01-15 09:49

本文关键词：钙钛矿基氧化物材料的制备及电化学性能研究　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：固体氧化物燃料电池(SOFC)可以将燃料中的化学能直接转变为电能。为了提高SOFC的电化学性能,寻找中低温条件下具有优越性能的阴极材料成为一个重要方向。钙钛矿基氧化物材料具有较高的电导率以及稳定性,成为人们研究的热点。本文以溶胶-凝胶法(sol-gel)制备了钙钛矿基氧化物阴极材料GdBaCo_2O_(5+δ)(GBCO)、SrFeO_(3-δ)(SFO)以及不同元素掺杂的氧化物材料,探讨了其电化学性能,具体内容如下:本文合成了双钙钛矿型氧化物阴极材料GdBaCo_2O_(5+δ)(GBCO)及Sr元素掺杂的GdBa0.7Sr0.3Co_2O_(5+δ)(GBSCO),并制备了Ce0.9Gd0.1O2(GDC)电解质材料;为进一步优化电化学性能,构筑了GDC骨架/GDC电解质结构,并以质量比7:3的比例制备了GBSCO-GDC复合材料。将阴极材料在电解质上组装成不同体系的半电池:GBCO/GDC、GBSCO/GDC、GBSCO-GDC/GDC和GBSCO/GDC骨架/GDC,并采用三电极法进行电化学性能测试。对制备的粉体、电解质片以及半电池利用热重分析(TG)、X-射线衍射仪(XRD)和扫描电子显微镜(SEM)等进行性能表征。XRD结果表明,GBCO和GBSCO阴极粉体在950 ℃煅烧2 h后,具有良好的结晶性能,且GBSCO与GDC电解质材料在950 ℃煅烧1 h后没有发生化学反应。相比致密的GDC电解质片,GDC骨架层呈现均匀多孔结构,粗糙度更高,GBSCO阴极材料与骨架层之间具有良好的连接性能,没有出现大面积裂纹及孔洞。采用交流阻抗法和线性扫描法测试不同温度下半电池的电化学性能。结果表明:Sr元素掺杂的GBSCO阴极材料电化学性能得到明显改善,700 ℃时,GBSCO/GDC半电池的面积比界面电阻为0.547Ω·cm~2,明显小于GBCO/GDC半电池;当测试电压为0.8 V时,阴极电流密度达到0.209 A·cm-2;700 ℃时GBSCO/GDC、GBSCO-GDC/GDC和GBSCO/GDC骨架/GDC半电池的面积比界面电阻分别为0.547Ω·cm~2、0.166Ω·cm~2、0.118Ω·cm~2;测试电压为0.8 V时,阴极电流密度分别为0.209 A·cm-2、0.458 A·cm-2、0.763 A·cm-2。复合阴极及电解质骨架的使用,有效改善了半电池的电化学性能,通过对比发现,GBSCO阴极材料在GDC骨架表面受到的极化作用的影响最小,表现出最好的电化学性能。Co基虽然有着较高的导电率,但Co具有一定毒性,价格高,不利于SOFC商业化应用的发展。非Co基钙钛矿型氧化物由于具有较高的离子-电子导电性、良好的稳定性以及合适的价格,成为一类值得关注的阴极材料。本文制备了SrFeO_3-δ(SFO)以及Cu、Mo元素掺杂的SrFe_(0.7)Cu_(0.2)Mo_(0.1)O_(3-δ)(SFCM)钙钛矿型阴极材料,研究烧结温度对物相结构、微观形貌和电化学性能的影响。XRD结果表明,800 ℃煅烧2 h的SFO和SFCM形成立方钙钛矿结构,且SFCM阴极与GDC电解质材料在800 ℃温度下煅烧后,未发生化学反应,具有良好的高温化学相容性。对SFO/GDC、SFCM/GDC、SFCM-GDC/GDC以及SFCM/GDC骨架/GDC半电池电化学性能进行测试。结果表明:750 ℃时,SFO/GDC半电池面积比界面电阻高达1.19Ω·cm~2,远高于SFCM/GDC半电池(0.492Ω·cm~2)。700 ℃时,SFCM/GDC半电池的面积比界面电阻达到1.06Ω·cm~2,SFCM-GDC复合阴极以及GDC骨架层的使用使得面积比界面电阻分别降低了0.700Ω·cm~2和0.77Ω·cm~2;测试电压为0.8 V时,SFCM阴极材料在GDC骨架/GDC电解质表面电流密度达到0.641 A·cm-2,表现出最优异的电化学性能。以上结果表明:Cu、Mo元素掺杂的钙钛矿型氧化物明显提高了阴极材料的电化学性能,复合阴极材料及电解质骨架层的使用可以有效提高半电池的电化学性能。在室温条件下,将SFCM阴极粉体制备成薄膜工作电极,在0.1 mol/L的KOH碱性电解液中,采用三电极法利用旋转环盘电极测试氧还原反应极化曲线以及循环伏安曲线,对其氧还原反应催化性能进行表征。测试结果表明,随着SFCM工作电极转速的增加,氧还原反应极限电流密度不断增加,在2400 rpm时达到4.42mA/cm~2;在CV曲线中,正电位向负电位扫描的氧还原过程中出现较强的还原峰,SFCM阴极粉体具有较强的氧还原催化活性。
[Abstract]:Solid oxide fuel cell (SOFC) can be in the fuel chemical energy directly into electrical energy. In order to improve the electrochemical performance of SOFC cathode material has superior performance, find in low temperature condition has become an important direction. The electric conductivity and stability of perovskite oxide material has high, become the focus of the research in this paper. With sol gel (sol-gel) perovskite based oxide cathode materials were synthesized by using GdBaCo_2O_ (5+ 8) (GBCO), SrFeO_ (3- 8) (SFO) and different element doped oxide materials, discusses its electrochemical properties, the specific contents are as follows: double perovskite type oxide cathode material GdBaCo_2O_ was synthesized in this paper (5+ 8) (GBCO) and Sr doped GdBa0.7Sr0.3Co_2O_ (5+ 8) (GBSCO), and preparation of Ce0.9Gd0.1O2 (GDC) electrolyte materials; to further optimize the electrochemical performance, build a framework of GDC /GDC structure and electrolyte. GBSCO-GDC composite materials were prepared with the mass ratio of 7:3. The cathode material in the electrolyte assembled into different systems: GBCO/GDC, GBSCO/GDC, half cell GBSCO-GDC/GDC and GBSCO/GDC skeleton /GDC, and using three electrode method. The electrochemical performance of powder preparation, analysis of electrolyte and half battery use heat (TG), X- ray diffraction (XRD) and scanning electron microscopy (SEM) and characterization of.XRD showed that GBCO and GBSCO cathode powder calcined at 950 after 2 h, good crystallization performance, and the GBSCO and GDC electrolyte at 950 8C 1 h did not occur after the chemical reaction compared GDC electrolyte density, GDC skeleton layer exhibits a uniform porous structure, higher roughness, has the good performance of the connection between GBSCO cathode materials and the skeleton layer, no large area cracks and holes. The AC impedance and linear sweep The electrochemical properties of the half cell tracing test under different temperature. The results showed that the electrochemical performance of GBSCO cathode materials doped Sr were improved significantly, 700 degrees, GBSCO/GDC half cell area than the interface resistance of 0.547 cm~2, GBCO/GDC was significantly less than the half cell; when the test voltage is 0.8 V, the cathodic current density reached 0.209 A - cm-2; 700 degrees GBSCO/GDC, GBSCO-GDC/GDC and GBSCO/GDC framework /GDC half cell area were 0.547. Cm~2,0.166. Cm~2,0.118. Cm~2 is the interface resistance; the test voltage is 0.8 V, the cathodic current density was 0.209 A cm-2,0.458 A using cm-2,0.763 A cm-2. composite cathode and electrolyte skeleton effectively, improve the electrochemical performance of the half cell, by contrast, influence of GBSCO cathode material in the polarization of GDC by the surface of the frame is minimum, showed the best electrochemical.Co base is It has a high conductivity, but Co has a certain toxicity, the high price is not conducive to the development of SOFC commercial application. Co based perovskite oxides due to ion with high electronic conductivity, good stability and reasonable price, become a concern of the cathode material. The preparation of SrFeO_3- 8 this system (SFO) and Cu, Mo doped SrFe_ (0.7) Cu_ (0.2) Mo_ (0.1) O_ (3- 8) (SFCM) perovskite type cathode materials, the effects of sintering temperature on the phase structure, the effect of.XRD microstructure and electrochemical performance showed that 800 8C 2 h and SFO the formation of SFCM cubic perovskite structure, and SFCM cathode and GDC electrolyte material at 800 DEG C temperature after calcination, without chemical reaction, with high temperature chemical compatibility. For SFO/GDC, SFCM/GDC, SFCM-GDC/GDC and SFCM/GDC framework /GDC half cell electrochemical properties were tested. The results showed that: 750 degrees, SFO/GDC half cell area ratio of interface resistance as high as 1.19. Cm~2, far higher than the SFCM/GDC half cell (0.492. Cm~2).700 C, SFCM/GDC half cell area than the interface resistance reached 1.06. Cm~2, SFCM-GDC and GDC composite cathode skeleton layer makes the interface resistance area ratio were decreased 0.700. Cm~2 and 0.77. Cm~2; the test voltage is 0.8 V, the SFCM cathode material in the GDC skeleton of /GDC electrolyte surface current density reached 0.641 A - cm-2, exhibited excellent electrochemical performance. The above results show that: Cu, perovskite type oxide doped Mo significantly improves the electrochemical performance of cathode material the use of composite cathode material and electrolyte, the skeleton layer can effectively improve the electrochemical performance of the half cell. At room temperature, the SFCM cathode powder into thin film electrode in alkaline electrolyte, KOH 0.1 mol/L, the Using the rotating ring disk electrode test oxygen reduction reaction polarization curves and cyclic voltammetry curves of three electrode method, catalytic performance of oxygen reduction was investigated. The test results show that with the increase of SFCM speed of the working electrode, the oxygen reduction reaction limit current density increased, reaching 4.42mA/cm~2 at 2400 rpm; the CV curve, positive potential the reduction of negative potential scanning oxygen reduction peak appears for strong in the process of SFCM cathode powder has strong catalytic activity for oxygen reduction.

【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB34;TM911.4

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