摘要

本文研究了氧化物 Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ) (x=0,0.5,0.6,0.7)，並對它們的結構進行了研究。這些氧化物被用於製造質子傳輸固體氧化物燃料電池（P-SOFC）的陰極以探索其性能。還研究了浸潤氧化銅對陰極的改性。

在硝酸鹽溶液中，調整甘氨酸/硝酸鹽pH並使用燃燒合成法製造前驅粉末。收集燃粉末並在不同溫度下煆燒再使用XRD找出最佳晶體。通過SEM檢查粉末的表面形態。使用兩個不同的模具中將粉末壓製成長錠以及圓錠，在1100℃下燒結測量其歐姆阻抗和熱膨脹係數。使用Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ) 粉末與萜品醇均勻混合配置成陰極膏並塗抹在電解液〖Ba Ce〗_0.8 Zr_0.1 Y_0.1 O_3(BCZY)的其中一面來當作陰極，並在其另一側上塗覆白金膏來當作陽極以形成全電池(Pt/〖Ba Ce〗_0.8 Zr_0.1 Y_0.1 O_3/Ba_(1-x) Ca_x Co_(0"." 2) Fe_0.8 O_(3-δ) )。最後再浸潤CuO並測量其電池的功率密度和電化學阻抗譜(EIS),參數為在800 ℃操作溫度下陰極空氣進口流量為200c.c./min，陽極氫氣流量為450c.c./min。
結果表明，Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ) 製備的陰極中，隨著鈣含量從x = 0.5增加到x = 0.7，電池的功率增加。但是浸潤氧化銅顆粒（CuO）（CuO : Ba_0.3 Ca_0.7 Co_(0"." 2) Fe_0.8 O_(3-δ)= 1/1 質量比）對功率密度沒有任何顯著影響並增加了極化電阻。

Abstract

Oxides Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ) (x=0,0.5,0.6,0.7) were prepared and their structures, propertied were studied in this thesis. These oxides were employed to fabricate the cathodes for the proton-transport solid oxide fuel cell (P-SOFC) to explore their performance. Modification of the cathodes by infiltration of copper oxide was also investigated.

The powders were synthetized by a glycine/nitrate combustion process under a control of pH value in the nitrate solution. The combustion ashes were collected and subjected to calcination at different temperatures to find out best crystals of the related phases according to X-ray diffraction (XRD) patterns. Surface morphology of the powders was examined by scanning electron microscope (SEM). All powders were pressed in two different molds and sintered at 1100°C to make samples for measurement of their ohmic resistance and thermal expansion behavior. Each kind of Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ) powders was mixed with the binder to make a paste. Then the paste was screen-painted on one side of an electrolyte (i.e., 〖Ba Ce〗_0.8 Zr_0.1 Y_0.1 O_3) and the Pt-paste on other side of it to make a single cell. The power density and electrochemical impedance spectroscopy (EIS) for the single cell of Pt/〖Ba Ce〗_0.8 Zr_0.1 Y_0.1 O_3/Ba_(1-x) Ca_x Co_(0"." 2) Fe_0.8 O_(3-δ), and for that of Pt/〖Ba Ce〗_0.8 Zr_0.1 Y_0.1 O_3/Ba_0.3 Ca_0.7 Co_(0"." 2) Fe_0.8 O_(3-δ) infiltrated with CuO were tested at 800°C. The flow rates of air inlet on cathode was at 200 c.c./min and that of hydrogen on anode at 450 c.c./min.

The results indicated that the power density of the cell increased with increasing the calcium content from x=0.5 to x=0.7 in the cathode made from Ba_(1-x) Ca_x Co_0.2 Fe_0.8 O_(3-δ). Copper oxide particles (CuO) infiltration (with mass ratio CuO/Ba_0.3 Ca_0.7 Co_(0"." 2) Fe_0.8 O_(3-δ) =1/1) does not have any significant effect on power density and increased polarization resistance.

Table of Contents

Chapter 1. Introduction………..……….………………..………...........1
1.1. World energy need………………………………………………………..…...1
1.2. A brief history about fuel cell............................................................................4
1.2.1. Principles and categories of fuel cells ………………...……....................5
1.3. Fundamental cathode materials………………………………...………….....9
1.3.1. Simple Perovskites……………………………………….….…….…....12
1.3.2. Layered Perovskites ………………….………………………..…........19
1.3.3. Ruddlesden-Popper phases……………………………………...….......21

Chapter 2. Motivation………………………………………..….….….23
2.1. SOFC challenges and drawbacks………..……………………………....…..23
2.1.1. Cathode design………………………………..……………..………......25

Chapter 3. Literature survey……………….…………………….……28
3.1. Particle deposition on cathode …………………………..……...……….…..28
3.1.1. Ionic conducting infiltrates………………………………………..….....28
3.1.2. Partial of MIEC infiltrated into MIEC scaffold……………………........31
3.1.3. Particles of precious metal infiltrated into MIEC cathode scaffold……..35
3.2. Thin film coating on MIEC cathode……………………………………......36
3.3. Effects of calcium doping……………….…………………………………...44

Chapter 4. Materials, preparation and characterization methods….52
4.1. Powder preparation……………………………………………………..........52
4.2. Basic characterization………………………………………………..............59
4.2.1. XRD……………………………………………………...…………........59
4.2.2. SEM……………………………………………………………………...60
4.2.3. Thermo-gravimetric analysis (TGA)………………………………..…...62
4.2.4. Thermo-mechanical analysis………………………………………….....62
4.2.5. Ohmic resistance measurement………………………………………….66
4.3. Cell fabrication and testing………………………………………………......71
4.3.1. Cell fabrication and power density measurements………………………71
4.3.2. Electrochemical Impedance Spectroscopy ………………………….......87

Chapter 5. Results and Discussion…………....…………………….…90
5.1. Phase identification and XRD patterns……………………………….…….90
5.2. SEM images……………………………………………………………….....100
5.3. Thermo-gravimetric analysis (TGA)…………………………………….…102
5.4. Thermo-mechanical analysis………………………………………………..106
5.5. Conductivity calculation results……..……………………………….….…107
5.6. EIS results………….………………………………………………..…...…..108
5.7. Power density measurements of cells……………………………….…..….110

Chapter 6. Conclusions and Outlook……………………..………....112
6.1. Conclusions………………………………………………………………....112
6.2. Outlook…………..………………………………………….……………….113

References…………………………………………………………………...…114

References

[1]. Marta Boaro, Antonino Salvatore Arico,''Advances in Medium and High Temperature Solid Oxide Fuel Cell Technology'', CISM International Centre for Mechanical Sciences, Courses and lectures, ISBN 978-3-319-46145-8, Springer, 2017, 574, 1-4

[2]. D. Ding, X. Li, S. Y. Lai, K. Gerdes, M. Liu, '' Enhancing SOFC cathode performance by surface modification through infiltration'', Energy Environ. Sci., 2014, 7, 553-564.

[3]. Küngas, Rainer, ''Factors Governing the Performance and Stability of Solid Oxide Fuel Cell Cathodes Prepared by infiltration'' (2012). Publicly Accessible Penn Dissertation. 529. 2-4.
https://repository.upenn.edu/edissertations/529

[4]. Retrieved from Sakurambu-own work: Diagram of Solid Oxide Fuel Cell, en.wikipedia.org/wiki/Solid-oxide –fuel-cell.

[5]. Zhan Gao, Liliana V. Mogni, Elizabeth C. Miller, Justin G. Railsback and Scott A. Barnett, Energy Environ. Sci., 2016, 9, 1611-1634.

[6]. S. Choi, S. Park, J. Shin, G. Kim, J. Mater. Chem. A, 2015, 3, 6088.

[7]. C. Lim, A. Jun, H. Jo, K. M Ok, J. Shin, Young-Wan Ju, G. Kim, J. Mater. Chem. A, 2016, 4, 6479.

[8]. J.C. Toniolo*, M.D. Lima, A.S. Takimi, C.P. Bergmann, '' Synthesis of alumina powders by the glycine–nitrate
combustion process'', Materials Research Bulletin, 2005, 40, 561–571.

[9]. M. Afzal, R. Raza, S. Du, R. B. Lima, B. Zhu, Electrochimia Acta, 2015, 178, 385-391.

[10]. Y. M. Al-Yuosef, M. Ghouse, World Journal of Nano Science and Engineering, 2011, 1, 99-107. doi:10.4236/wjnse.2011.14016 Published Online December 2011 (http://www.SciRP.org/journal/wjnse)

[11]. Venkateswara, R. K., et al. CuO nanoparticles Synthsis and characterization for Humidity Sensor Application. (2016) J Nanotech Mater Sci, 3(1): 10-14.
DOI: 10.15436/2377-1372.16.020
[12]. Y. Guo, Y. Lin, R. Ran, Z. Shao, J.Power Sources 193(2009) 400-407.

[13]. S. B. Adler, J. A. Lane and B. C. H. Steele, J. Electrochem. Soc., 1996, 143, 3554-3564.

[14]. J. Fleig and J. Maier, J. Eur. Ceram. Soc., 2004, 24, 1343-1347.

[15]. Y. Lu, C. Kreller and S. B. Adler, J. Electrochem. Soc., 2009, 156, B513-B525.

[16]. S. B. Adler, X. Y. Chen and J. R. Wilson, J. Catal., 2007, 245, 91-109.

[17]. Y. Lu, C. R. Kreller, S. B. Adler, J. R. Wilson, S. A. Barnett, P. W. Voorhees, H.-Y. Chen and K. Thornton, J. Electrochem. Soc., 2014, 161, F561-F568.

[18]. M. Shah, P. W. Voorhees and S. A. Barnett, Solid State Ionics, 2011, 192, 398-403.

[19]. J. Druce, H. Tellez and J. Hyodo, MRS Bull., 2014, 39, 810-815.

[20]. A. Mai, M. Becker, W. Assenmacher, F. Tietz, D. Hathiramani, E.Ivers-Tiffee, D. Stover and W. Mader, Solid state Ionics, 2006, 177, 1965-1968.

[21]. K. Sasaki, K. Haga, T. Yoshizumi, D. Minematsu, E. Yuki, R. R. Liu, C. Uryu, T.Oshima, Y. Shiratori, K. Ito, M. Koyama and K. Yokomoto, J. Power Sources, 2011, 196, 9130-9140.

[22]. S. J. Skinner, Fuel Cell. Bull., 2001, 4, 6-12.

[23]. H. Yokokawa, T. Horita, K. Yamaji, H. Kishimoto and M. E. Brito, J. Korean Ceram. Soc., 2012, 49, 11-18.

[24]. H. Yokokawa, H. Y. Tu, B. Iwanschitz and A. Mai, J. Power Sources, 2008, 182, 400-412.

[25]. L. Zhao, J. Drennan, C. Kong, S. Amarasinghe and S. P. Jiang, J. Mater. Chem. A, 2014, 2, 11114-11123.

[26]. C. W. Sun, R. Hui and J. Roller., J. Solid State Electrochem., 2010, 14, 1125-1144.

[27]. S. B. Adler, Solid State Ionics, 1998, 111, 125-134.