本文關(guān)鍵詞： 固體氧化物燃料電池 陰極材料 CuCo_2O_4 復(fù)合陰極 納米陰極　出處：《哈爾濱工業(yè)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：固體氧化物燃料電池(SOFC)是一種高效環(huán)保的電化學(xué)能源轉(zhuǎn)換器件。中溫化是目前國際SOFC領(lǐng)域的研究熱點(diǎn)及發(fā)展趨勢。然而,工作溫度的降低會導(dǎo)致陰極材料催化活性的大幅度下降,成為制約中溫SOFC發(fā)展的關(guān)鍵瓶頸之一。鈷基鈣鈦礦材料具有良好的中溫催化活性,但其與電解質(zhì)的熱、化學(xué)匹配性較差。本論文旨在提高陰極的中溫反應(yīng)活性,發(fā)展了一種新型、高性能電催化活性的SOFC陰極材料——尖晶石CuCo_2O_4,并對其物理化學(xué)性質(zhì)、與電解質(zhì)的相容性、電催化活性等進(jìn)行了全面的表征。實(shí)驗(yàn)中進(jìn)一步通過與高氧離子傳導(dǎo)電解質(zhì)復(fù)合構(gòu)建了多種微結(jié)構(gòu)的復(fù)合電極,深入研究探索了其反應(yīng)機(jī)制、微結(jié)構(gòu)與電化學(xué)性能之間的構(gòu)效關(guān)系。通過溶膠凝膠法制備CuCo_2O_4納米粉體。研究結(jié)果表明,當(dāng)檸檬酸(CA)與乙二胺四乙酸(EDTA)的摩爾比增加至1:1.5時,可得到單相的立方晶相尖晶石CuCo_2O_4材料,材料晶粒尺寸小,約為70-200 nm,顆粒大小均勻。該材料與SSZ電解質(zhì)具有較好的化學(xué)相容性,在50-900?C范圍內(nèi)的平均熱膨脹系數(shù)11.76×10-6 K-1,與氧化鈧穩(wěn)定的氧化鋯(SSZ)電解質(zhì)熱匹配性較好。在研究陰極燒結(jié)溫度、造孔劑對CuCo_2O_4陰極微觀形貌的影響規(guī)律基礎(chǔ)上,得到最優(yōu)的制備條件:陰極燒結(jié)溫度為1000?C,淀粉添加25 wt.%。在800?C時,極化電阻為0.12W?cm2,單電池的最大功率密度972 m W?cm-2。為了提高CuCo_2O_4陰極的電催化反應(yīng)活性,增加CuCo_2O_4陰極中的三相反應(yīng)界面長度,研究中,在陰極中引入10 mol%Sc2O3穩(wěn)定的Zr O2(SSZ)和Ce0.9Gd0.1O1.95(GDC)氧離子傳導(dǎo)材料。采用機(jī)械混合法制備復(fù)合陰極,CuCo_2O_4-SSZ復(fù)合陰極和CuCo_2O_4-GDC復(fù)合陰極的平均熱膨脹系數(shù)分別為11.39-11.86×10-6 K-1和11.83-12.20×10-6 K-1,與SOFC組件中其他組件熱匹配性較好。電化學(xué)測試結(jié)果表明,隨著復(fù)合陰極中氧離子電解質(zhì)含量的增加,可有效地增加陰極中的三相反應(yīng)界面長度,復(fù)合陰極化電阻減少,但含量過多時,會導(dǎo)致擴(kuò)散電阻增加,導(dǎo)致極化電阻反而增大。其中,GDC的復(fù)合量為60 wt.%時,復(fù)合陰極的性能最佳,在800?C時,陰極的極化電阻為0.09W?cm2,當(dāng)電流密度為0.5 A?cm-1時,CuCo_2O_4-GDC60復(fù)合陰極的陰極過電位為74 m V。單電池最大輸出功率提高到1074m W?cm-2,展現(xiàn)出良好的穩(wěn)定性。為了改善CuCo_2O_4陰極的性能,采用離子浸漬法原位制備CuCo_2O_4/SSZ納米結(jié)構(gòu)復(fù)合陰極。研究中考察了浸漬液的濃度、浸漬量及燒結(jié)溫度對浸漬陰極微觀結(jié)構(gòu)的影響,得到浸漬液為0.025 mol/L時,浸漬CuCo_2O_4顆粒更均勻,浸漬4-5次,相對也較少。浸漬量為17.6 wt.%時,浸漬CuCo_2O_4效果較好。研究中發(fā)現(xiàn)燒結(jié)溫度對浸漬CuCo_2O_4顆粒長大的影響不是很大,這可能是由于浸漬法制備材料過程中,熱分解較低(360?C)。同時,SSZ多孔骨架有效地抑制了CuCo_2O_4的長大過程,保證了CuCo_2O_4沒有出現(xiàn)粗化等現(xiàn)象。最終得到的納米復(fù)合陰極結(jié)構(gòu)穩(wěn)定,SSZ多孔骨架有效地增加了三相反應(yīng)界面區(qū)域和長度,提升CuCo_2O_4納米陰極的氧化原催化活性,電化學(xué)性能得到明顯提升,最佳浸漬量為17.6 wt.%的浸漬陰極具有最小的極化電阻,在800?C為0.08Ω?cm2,單電池最大輸出功率為1136 m W?cm-2。同時,對浸漬CuCo_2O_4浸漬陰極的氧還原反應(yīng)機(jī)制進(jìn)行研究,得出氧離子在電極或從電極到電解質(zhì)的三相反應(yīng)界面的擴(kuò)散過程是該電極反應(yīng)的速率控制步驟。
[Abstract]:Solid oxide fuel cell (SOFC) is an efficient electrochemical energy conversion devices. The environmental temperature is research hotspot and development trend of the international SOFC field at present. However, lower working temperature will cause the cathode catalytic activity decreased greatly, become one of the key bottlenecks restricting the development of the temperature SOFC cobalt based perovskite. The temperature material has good catalytic activity, but the heat of the electrolyte, the chemical matching is poor. In this paper in order to improve the temperature and reaction activity of the cathode, the development of a new type of cathode, SOFC - spinel CuCo_2O_4 materials with high performance of electro catalytic activity, and the physical and chemical properties, compatibility with electrolyte. The electrocatalytic activity of the comprehensive experimental characterization. Further with high oxygen ion conducting electrolyte composite constructed composite electrodes with various microstructures, in-depth study and exploration of the reaction The mechanism and structure-activity relationship between microstructure and electrochemical properties. The preparation of CuCo_2O_4 nano powders by sol gel method. The results showed that when citric acid (CA) and EDTA (EDTA) molar ratio increased to 1:1.5, can get the single-phase cubic spinel CuCo_2O_4 material, material grain size is about 70-200. Nm, the particle size is uniform. The material with SSZ electrolyte has good chemical compatibility, in 50-900? The average thermal expansion coefficient of C within the range of 11.76 * 10-6 K-1, zirconium oxide and scandium oxide (SSZ) electrolyte heat stable matching is better. In the study of cathode sintering temperature, based on the CuCo_2O_4 cathode pore forming agent the influence of microstructure, the optimal preparation conditions are: cathode sintering temperature is 1000? C, starch adding 25 wt.%. at 800? C, the polarization resistance for 0.12W? Cm2, the maximum power density of 972 m W single cell cm-2. in order to improve the Cu? The electrocatalytic activity of Co_2O_4 cathode, increase of three-phase reaction interface length, CuCo_2O_4 cathode, introduced 10 mol%Sc2O3 stable Zr O2 in the cathode (SSZ) and Ce0.9Gd0.1O1.95 (GDC) oxygen ion conducting materials. The composite cathode with mechanical mixing method, CuCo_2O_4-SSZ composite cathode and the average thermal expansion coefficient of CuCo_2O_4-GDC composite cathode are 11.39-11.86 * 10-6 K-1 * 10-6 K-1 and 11.83-12.20, and other components of thermal SOFC components in good matching. The electrochemical test results show that with the increase of electrolyte content of composite cathode, can effectively increase the three-phase reaction interface length in the cathode polarization resistance, Yin composite decreased, but the content is too much, will to increase the resistance of diffusion, resulting in polarization resistance increases. The composite amount of GDC is 60 wt.%, the best performance of the composite cathode, at 800? C, cathodic polarization Resistance is 0.09W? Cm2, when the current density is 0.5 A? Cm-1, CuCo_2O_4-GDC60 composite cathode cathode overpotential is improved by 74 m V. single battery maximum power output to 1074m W? Cm-2, showing good stability. In order to improve the performance of CuCo_2O_4 cathode, by ion impregnation method for in situ preparation of nano CuCo_2O_4/SSZ composite cathode on the effects of the concentration of impregnation solution, impregnation impregnation amount and sintering temperature on the microstructure of the cathode by impregnating solution was 0.025 mol/L, dipping CuCo_2O_4 particles more evenly, dipping 4-5 times less. The dipping amount was 17.6 wt.%, the CuCo_2O_4 effect is not great. Good impregnation effect of sintering temperature to grow up on the impregnation of CuCo_2O_4 particles found in the study, this may be due to the material prepared by impregnation process, the thermal decomposition of low (360? C). At the same time, SSZ porous skeleton can efficiently inhibit the CuCo_2O_4 grown up The process, to ensure that the CuCo_2O_4 does not appear coarsening phenomenon. The nano composite cathode structure stable final, SSZ porous skeleton can effectively increase the three-phase reaction interface area and length, enhance the redox catalytic activity of CuCo_2O_4 nano cathode, electrochemical performance can be improved significantly, the best impregnation for impregnated cathode 17.6 wt.% with polarization resistance in 800, the minimum is 0.08 ohms? C? Cm2, the maximum output power of single cell was 1136 m W? Cm-2. CuCo_2O_4 at the same time, dipping on the impregnated cathode oxygen reduction reaction mechanism of the oxygen ion in the electrode or from the electrode to the diffusion process of three phase reaction interface electrolyte is the rate controlling step of the electrode reaction.

【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TM911.4

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