直接碳固体氧化物燃料电池新型钙钛矿阳极材料研究

【作者】 陈晓；

【导师】 张英杰；

【作者基本信息】 昆明理工大学 ， 材料物理与化学， 2023， 硕士

【摘要】 为了遏制不断恶化的环境问题和能源危机,我国大力开发新能源技术,但是煤炭作为我国主体能源的地位不可撼动。而直接碳固体氧化物燃料电池（DC-SOFC）作为一种新型高效清洁的煤炭发电技术,对于传统燃煤发电技术的改革和双碳目标的实现具有崇高的战略意义。由于阳极是直接碳固体氧化物燃料电池的主要反应场所,高催化活性、稳定且抗积碳的阳极材料的开发一直是DC-SOFC领域的研究热点和重点。钙钛矿材料作为优异的电子-离子混合导体以其良好的电催化活性、结构可调控性、稳定性及优异的抗积碳和硫中毒等优势获得研究者的青睐。本论文围绕直接碳固体氧化物燃料电池高催化活性的钙钛矿阳极材料展开研究,并实现了钒掺杂单钙钛矿阳极材料和原位脱溶纳米合金颗粒的层状钙钛矿阳极材料的设计和开发。首先,设计并制备了单钙钛矿阳极材料La_0.5Sr_0.5Fe_1-xV_xO_3-δ（LSFV_x）。掺杂V后,LSFV_x内部形成了连续电子传导通道和更多的氧空位有利于电子转移和氧离子扩散,使阳极材料对碳燃料的电化学氧化过程表现出优异的电催化效果,同时确定了V的最佳掺杂量为x=0.1。在850℃下,以LSFV_0.1为阳极的DC-SOFC最大功率密度和极化电阻分别为249 m W cm^-2和0.37Ωcm²,恒流放电下电池的最长放电时间为8.65 h,热解褐煤燃料利用率最高为38.76%,明显优于纯LSFO_3-δ阳极材料(170 m W cm^-2)。同时过量的钒掺杂(LSFV_0.15)会降低氧空位浓度,使气体的吸附和扩散过程受阻,进而导致电池电化学性能的降低。电池稳定性测试后的SEM和XRD结果表明,LSFV_x钙钛矿阳极材料具有极好的结构稳定性和氧化还原稳定性。为了进一步提高DC-SOFC的电化学性能,设计并制备了原位脱溶合金颗粒的(Pr_0.4Sr_0.6)₃(Fe_0.85Nb_0.15)₂O₇层状钙钛矿用于DC-SOFC阳极材料的研究。采用燃烧法合成了蓬松多孔的立方相钙钛矿结构材料（P-PSMFN,M=Co,Ni）。通过一步热还原法使得P-PSMFN（M=Co,Ni）阳极材料发生原位自组装过程,将立方相钙钛矿结构转变成层状钙钛矿结构RP-PSMFN（M=Co,Ni）,并在表面原位脱溶生长出纳米合金颗粒,对阳极侧碳的氧化反应具有优异的电催化活性,电池展现了优异的电化学性能。同时采用固相法制备了与层状钙钛矿阳极材料相匹配的LSGM电解质材料,LSGM电解质材料具有优异的氧离子电导率,且内部结构致密。组装了RP-PSMFN（M=Co,Ni）|LDC|LSGM|Ag-GDC结构的DC-SOFC。原位脱溶Co Fe合金的RP-PSCFN和Ni Fe合金的RP-PSNFN阳极材料的电化学性能相当,最大功率密度和极化电阻分别为281和284 m W cm^-2以及0.34和0.32Ωcm²,电池稳定运行13 h,热解褐煤燃料利用率达58.21%。与Ag-GDC为阳极的电池性能相比,原位脱溶的Co Fe合金和Ni Fe纳米合金颗粒具有更优异的电催化活性,能显著提高电池的电化学性能。更多还原

【Abstract】 Up to date,new energy technologies have been energetically developed to tackle the long-standing issues of environmental pollution and energy crisis,yet the coal fuel in China still dominates in the energy structure and its status is unshaken.Direct carbon solid oxide fuel cell（DC-SOFC）,as a new high-efficiency and clean coal power generation technology,is strategically significant for the revolution of traditional coal-fired power generation technology and the realization of the dual-carbon goal.Since the anode is the main reaction site of DC-SOFCs,the development of anode materials with high catalytic activity,stability,and resistance to carbon deposition has become the research focus in the DC-SOFC field.As an excellent electron-ion mixed conductor,perovskite materials are favored by researchers due to their good electrocatalytic activity,structure regulation,stability and high resistance to carbon deposition and sulfur poison.This thesis focuses on the investigation of perovskite anode materials with high catalytic activity for direct carbon solid oxide fuel cells,and has successfully developed vanadium doped single perovskite anode materials and layered perovskite anode materials in-situ exsolution of alloy nanoparticles.Firstly,a single perovskite anode material,La_0.5Sr_0.5Fe_1-xV_xO_3-δ（LSFV_x）was designed and prepared.After doping with V element,continuous electron conduction channels and more oxygen vacancies are formed inside LSFV_x,which are conducive to electron transfer and oxygen ion diffusion,enabling the anode material to exhibit excellent electrocatalytic activity on the electrochemical oxidation process of carbon fuel.At the same time,it is determined that the optimal doping amount of V is 0.1.At 850℃,the maximum power density and polarization resistance of DC-SOFC with LSFV_0.1 anode operated on brown coal char fuel are 249 m W cm^-2 and 0.37Ωcm²,respectively,along with the longest discharge time of 8.65 h,and the highest fuel utilization of 38.76%,which is significantly better than that of pure LSFO_3-δanode material(170 m W cm^-2).In addition,excessive vanadium doping(LSFV_0.15)will decrease the concentration of oxygen vacancies,hindering the gas adsorption and diffusion process,which will lead to the deterioration of the electrochemical performance of the DC-SOFC.The SEM and XRD results after the cell stability tests show that the LSFV_xperovskite anode materials have great structural and redox stability.Then,in order to further improve the electrochemical performance of DC-SOFC,(Pr_0.4Sr_0.6)₃(Fe_0.85Nb_0.15)₂O₇ layered perovskites with in-situ exsolution alloy particles were engineered and fabricated as DC-SOFC anode materials.A fluffy and porous cubic perovskite structure material（P-PSMFN,M=Co,Ni）was synthesized by combustion method.Through a one-step thermal reduction method,the P-PSMFN（M=Co,Ni）anode materials undergo an in situ self-assembly process,transforming the cubic perovskite structure into a layered perovskite structure,RP-PSMFN（M=Co,Ni）.And the nano-alloy particles were in situ exsolved on the surface,which show high electrocatalytic activity for the oxidation of carbon on the anode side and good electrochemical performance of the DC-SOFCs.Moreover,the LSGM electrolyte material matching the layered perovskite anode was prepared by a solid-state method.The LSGM electrolyte material has excellent oxygen ion conductivity and a dense internal microstructure.Then,DC-SOFCs with the configuration of RP-PSMFN（M=Co,Ni）|LDC|LSGM|Ag-GDC were assembled.The results show that performance of the RP-PSCFN with Co Fe alloy anode is comparable to the one of RP-PSNFN with Ni Fe alloy anode,with maximum power density and polarization resistance of281 m W cm^-2 versus 284 m W cm^-2,and 0.34Ωcm² versus 0.32Ωcm²,respectively.The cell with RP-PSCFN anode runs stably for up to 13 h,and fuel utilization of the brown coal char is up to 58.21%.Compared with traditional Ag-GDC anode,in situ exsolved Co Fe alloy and Ni Fe nanoalloy particles show superior electrocatalytic activity,which could remarkably enhance the electrochemical performance of the cell.更多还原