基于CuO敏感电极的阻抗谱型NO_x传感器的研究

采用共压共烧法来制备YSZ(掺杂0.8%MnO_2)固体电解质及多孔层,使用湿浸渍技术制备敏感材料CuO,并组装成传感器。采用SEM对材料表面和断面的微观形貌进行分析,通过XRD对材料的相组成进行分析,使用电化学工作站对材料的电导率和传感器的敏感性能进行了研究。实验表明,所制得的固体电解质层和多孔层结合紧密,掺杂MnO_2的电解质电导率(800℃)达10-2的数量级,满足电解质对电导率的要求,MnO_2的掺杂可以有效降低YSZ固体电解质的烧结温度;在650℃时,随着NO2浓度逐渐升高相角逐渐增大而阻抗逐渐减小,在低频0~30Hz之间曲线区分较好。650℃时,CuO传感器对NO_2有良好的响应。     

亚微米晶粒氧化钇稳定氧化锆电解质的稳定性

氧化钇稳定氧化锆(yttria-stabilized zirconia,YSZ)是目前使用最多的电解质材料,YSZ结构和性能的长期稳定对固体氧化物燃料电池(solid oxide full cell,SOFC)系统的可靠性至关重要。重点研究了具有亚微米结构的YSZ在850℃环境中的长期老化性能,结果发现:在850℃空气气氛中老化处理300h后,YSZ中小于1μm的部分晶粒出现了继续生长的现象,使得小于1μm晶粒比例下降10%～20%;当这部分晶粒长大到1～2μm,呈现稳定状态,即没有出现晶粒的过分长大;老化600h和1000h后,小晶粒(小于1μm)所占比例几乎不变。伴随着晶粒尺寸分布变化,YSZ电解质的电导率也比老化处理初期(300h)有所降低;当老化处理600h后,电导率下降趋势变缓;老化处理1000h后,电导率基本稳定,且1000℃电导率仍然保持在0.15S/cm以上。电导率下降主要是由YSZ晶粒部分长大引起的。具有上述性能的YSZ用作SOFC电解质可以满足长期使用的要求。     

添加3Y-TZP对8YSZ电解质材料的力学和电学性能的影响

采用机械混合方法,在8YSZ电解质材料中添加3Y-TZP,目的是在满足YSZ电解质电学性能要求的前提下,提高材料的力学性能.试样在常压下烧结,通过弯曲强度﹑断裂韧性﹑电导率测定和相组成分析,讨论了3Y-TZP添加量的影响.实验结果表明:加入3Y-TZP能显著提高陶瓷体的力学性能,弯曲强度和断裂韧性随着添加量的增多而提高;电学性能在0～30%(质量百分比,下同)的添加量时下降很小.添加30% 3Y-TZP的电解质材料在1000 ℃电导率为0.11 S/cm,强度接近300 MPa,综合效果最好.     

NiO/YSZ浆料凝胶固化、干燥、排胶及烧结工艺研究

采用凝胶注模工艺制备固体氧化物燃料电池(SOFC)阳极材料NiO/YSZ是目前的研究热点之一.本文主要研究了凝胶注模工艺中引发剂和催化剂的加入量对凝胶固化时间的影响,干燥温度对坯体失重的影响,固相含量、造孔剂的种类及用量对瓷体收缩率的影响,并对还原后瓷体的电性能进行了表征.采用SEM、EDS方法分析表征样品.实验结果表明:在实验选定的100 mL浆料中,浓度为5wt%引发剂的加入量为2.0 mL,浓度为0.5vol%催化剂的加入体积量为1.0 mL,凝胶时间可以控制在20 min以内.NiO/YSZ阳极材料最佳干燥温度是25 ℃,固相含量为45vol%、采用15wt%石墨作为造孔剂,在1350 ℃烧成的NiO/YSZ阳极与固体电解质YSZ收缩率相匹配,氢气还原后NiO/YSZ阳极在600～800 ℃电导率达到800 S/cm,符合SOFC阳极材料电导率的要求.     

钙钛矿型中温固体电解质La0.9Sr0.1Ga0.8Mg0.2O3-δ的制备

以硝酸盐为前驱体合成了具有钙钛矿结构的中温固体电解质La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM)。用XRD和SEM分析了样品钙钛矿相的形成过程和显微结构,用直流四电极法测试了电解质的氧离子电导率。研究结果表明:经1 450℃煅烧6 h后得到LSGM单相结构,800℃时的电导率为6.8×10-2S.cm-1,高于同温下钇稳定氧化锆(YSZ)样品的电导率,表明LSGM更适合做中温固体氧化物燃料电池(SOFC)的电解质材料。     

ZnO对8YSZ电解质材料的烧结性与电化学性能的影响

用机械混合方法,在8%(摩尔分数,下同)Y2O3稳定的ZrO2(8%in mole yttria stabilized zirconia,8YSZ)中添加ZnO量分别为0,1%,2%,3%,4%,在不同温度下常压烧结制备了ZnO:8YSZ电解质。研究了烧结温度和ZnO含量对ZnO:8YSZ样品的烧结性、致密度、弯曲强度和电导率的影响。由ZnO:8YSZ电解质作为支撑组装了单电池,对电池的性能进行测试和评价。结果表明:在8YSZ中添加ZnO能改善8YSZ材料的烧结性,1400℃烧结2h的4%ZnO:8YSZ样品的致密度达99.9%,3%ZnO:8YSZ样品的弯曲强度超过200MPa,获得明显提高。4%ZnO:8YSZ样品在800℃下的电导率达1.68×10-2S/cm。在相同工作条件下,ZnO:8YSZ单电池比8YSZ单电池具有更好的工作性能和更高的效率,以3%ZnO:8YSZ单电池性能最好。     

添加Li_2O对YSZ电解质性能影响

8%（摩尔分数,下同）Y2O3稳定的ZrO2（8YSZ）是固体氧化物燃料电池（SOFC）中最常用的电解质材料,本文研究了在8YSZ基体中加入n%Li2O（n=0,0.25,0.50,1.00,1.50,1.70,2.00,2.50,3.00）后（记为n%Li2OYSZ）对其晶相结构、晶格常数、烧结性能、微观形貌、电导率及其作为SOFC电解质性能的影响。结果表明,Li2O中的Li＋可以固溶到YSZ的晶格内使其晶格常数减小;Li2O的加入量n〈1.70时,瓷体在烧结过程中不会发生相变。加入少量的Li2O（n=0.25,0.50）可以提高YSZ的致密度和电导率,0.25%Li2OYSZ和0.50%Li2OYSZ样品800℃的电导率分别高达0.030 2 S/cm和0.027 6 S/cm,分别是纯YSZ的1.35和1.24倍;当Li2O含量n≥1.00时,相同条件下烧结体致密度随Li2O加入量的增大而逐渐减小;当n≥1.70时,样品在烧结过程中虽然出现相变,但在高于1400℃可以烧结致密,并得到纯立方相YSZ。将1250℃烧结制得的0.25%Li2OYSZ和0.50%Li2OYSZ作为SOFC电解质的单电池,800℃时的开路电压高于1.0V,说明YSZ中没有出现电子电导,具有比纯YSZ为电解质的单电池更高的性能输出,表现出了良好的应用前景。     

中温固体氧化物燃料电池电解质材料及其制备工艺的研究发展趋势

综合介绍了中温固体氧化物燃料电池(solid oxide fuel cells,SOFCs)的电解质材料以及薄膜的制备工艺.中温SOFCs的工作温度应低于800℃,甚至低于750℃,为600～800℃.固体氧化物电解质的晶体结构基本上属于下列两类:面心立方的萤石型和立方型钙钛矿晶体结构.稳定ZrO2是萤石型结构电解质的一个典型代表.8%(摩尔分数,下同)氧化钇稳定氧化锆(8%in mole Y2O3 stabilized ZrO2,8YSZ),其在1 000℃左右才有可观的离子电导率(0.1 S/cm).在800℃,氧化钪掺杂氧化锆(Zr0.9Sc0.1O1.95,scandia doped zirconia,SSZ)的电导率(0.1 S/cm)比Zr0.9Sc0.1O1.95(10YSZ)的(0.03S/cm)高得多.Sm掺杂的CeO2(samarium doped ceria,CSO)电解质有希望应用于中温SOFCs.Sr和Mg掺杂LaGaO3(LSGM)氧离子导体已成为中低温SOFCs重要候选电解质材料.改进氧化锆基电解质的电导性能的另一个途径是薄膜化.厚度小于10 μm的YSZ基SOFCs,在800℃,0.8V时的功率密度可达800mW/cm2.薄膜比厚膜能提供更好的化学均匀性和更易控制成分.SOFCs要求精细和尺度小时,通常选择薄膜;而低成本和大尺寸时,通常选择厚膜.成本较低的膜成型工艺有等离子喷涂、胶态成型工艺、流延成型、冷冻干燥成型、丝嘲印刷和真空泥浆浇注等.     

微波-凝胶法合成纳米Y2O3稳定ZrO2微粒的研究

研究以聚丙烯酰胺为分散剂,采用微波-凝胶法制备纳米Y2O3稳定ZrO2(YSZ)微粒的条件.分别用红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)及电测量技术,对纳米YSZ微粒的结构与性能进行了表征.结果表明:在650℃微波热处理得到立方相纳米YSZ微粒,平均粒径为35nm左右,在450～1000℃温度范围内呈现出较高的电导率,材料稳定性较好.     

固体氧化物燃料电池电解质材料的研究进展

固体氧化物燃料电池(SOFC)被誉为21世纪最具有发展潜力的能源材料之一,它的热效率高、燃料的适应性强,能很好地满足区域供电、供热的需要,具有重要的经济和社会意义。本文综述了SOFC电解质的研究进展,指出在诸多的电解质材料中,尽管氧化铋系电解质拥有最高的电导率,但由于其化学稳定性很差,难以获得广泛的应用;氧化钇全稳定的氧化锆(YSZ)由于其中低温的电导率较低,只适用于高温SOFC;稀土掺杂的氧化铈和LaGaO3钙钛矿材料拥有较高的中低温电导率,性质较为稳定,是适用于中低温SOFC的电解质材料。     

Electrical conductivity of YSZ-SDC composite solid electrolyte synthesized via glycine-nitrate method

Yttria-stabilized zirconia (YSZ) is a common solid electrolyte for solid oxide fuel cells (SOFCs) because of its high electrical conductivity and high ionic transference number in both oxidizing and reducing atmospheres. Samarium doped ceria (SDC) has also been considered as an alternative electrolyte material to YSZ for intermediate temperature SOFC because of its high conductivity at relatively low temperatures. Due to improved ionic conductivity of YSZ at high temperature (~ 800 °C) and good conductivity of SDC in the intermediate temperature range (600–800 °C), the electrical properties of YSZ-SDC composites were investigated. Composites of YSZ and SDC with weight ratio 9.5:0.5, 9:1 and 8.5:1.5 were synthesized via glycine-nitrate route. XRD pattern of the systems revealed the formation of composite phases. Biphasic electrolyte microstructures were observed, in which SDC grains are dispersed in YSZ matrix. Relative density of the compositions was found to be more than 92% to the theoretical density. It was observed that the interface provides a channel for ionic transport, leading to a notable ionic conductivity. With increase in SDC weight ratio the electrical conductivity was found to increase. For weight ratio 8.5:1.5 the electrical conductivity was found to be greater than that of YSZ in the temperature range 400–700 °C. Further, for weight ratio more than 8.5:1.5, conductivity was found to decreases due to the formation of a few other insulating impurity phases. The electrode polarisation was also found to reduce significantly with SDC in the composite electrolyte system. Thus, such composite system may be useful for improving the ionic conductivity of the composite electrolytes.     

Microstructure Control of Sintered Porous Yttria-Stabilized Zirconia as a Durable Thermal Shielding Material

The microstructure of a thermal shielding material affects its thermal conductivity and mechanical property. In this study, the effects of the sintering temperature and the polymethyl methacrylate powder as a pore-former on the microstructure of a sintered porous yttria-stabilized zirconia (YSZ), which is used as a durable thermal shielding material, were investigated. It became clear that the microstructure of the sintered YSZ could be controlled by the particle size and the amount of the pore-former and the sintering temperature. The effect of the yttria amount in the YSZ on the microstructure was also clarified.     

Interaction of a ceria‐based anode functional layer with a stabilized zirconia electrolyte: Considerations from a materials perspective

We report on the materials interaction of gadolinium‐doped ceria (GDC) and yttria‐stabilized zirconia (YSZ) in the context of high‐temperature sintering during manufacturing of anode supported solid oxide fuel cells (AS–SOFC). While ceria‐based anodes are expected to show superior electrochemical performance and enhanced sulfur and coking tolerance in comparison to zirconia‐based anodes, we demonstrate that the incorporation of a Ni–GDC anode into an ASC with YSZ electrolyte decreases the performance of the ASC by approximately 50% compared to the standard Ni–YSZ cell. The performance loss is attributed to interdiffusion of ceria and zirconia during cell fabrication, which is investigated using powder mixtures and demonstrated to be more severe in the presence of NiO. We examine the physical properties of a GDC–YSZ mixed phase under reducing conditions in detail regarding ionic and electronic conductivity as well as reducibility, and discuss the expected impact of cation intermixing between anode and electrolyte.     

双掺杂Bi_2O_3电解质的合成及其电性能测试

通过双掺杂氧化镝和氧化钨于氧化铋中,合成电解质并对其导电性进行测试。通过差热-热重来分析其热性能,确定其合成的烧结温度;并利用粉末X射线衍射对合成材料进行相分析,利用交流阻抗谱方法测试、计算试样的电导率。结果表明,烧结温度800℃时可得到具有高电导率相的立方相萤石结构的粉体,并无其它晶型出现。经计算,掺杂后的氧化铋电解质在700℃时电导率达18.7 S/m,比目前使用最普遍的电解质材料YSZ电导率在500℃时高1~2个数量级。     

Deposition Via Dip Coating Technique of Dense Yttrium Stabilized Zirconia Layers

A deposition of yttrium stabilized zirconia layer for its use as an electrolyte in solid oxide fuel cell was performed using dip coating technique. Two commercially available surfactant systems were evaluated; nonionic surfactant which stabilizes only by steric repulsion and anionic surfactant which provides both steric and electrostatic repulsion. Dip coating process was optimized to two step deposition process. Uniform 10–15 μm thick yttria stabilized zirconia (YSZ) electrolyte layer is obtained after the final sintering step at 1400°C. Impedance spectroscopy measurements showed that selected phosphate ester based surfactant has negligible effect on the performance of the YSZ material as electrolyte.     

Efficiently enhance the proton conductivity of YSZ-based electrolyte for low temperature solid oxide fuel cell

Yttrium stabilized zirconia (YSZ) as a typical oxygen ionic conductor has been widely used as the electrolyte for solid oxide fuel cell (SOFC) at the temperature higher than 1000 °C, but its poor ionic conductivity at lower temperature (500–800 °C) limits SOFC commercialization. Compared with oxide ionic transport, protons conduction are more transportable at low temperatures due to lower activation energy, which delivered enormous potential in the low-temperature SOFC application. In order to increase the proton conductivity of YSZ-based electrolyte, we introduced semiconductor ZnO into YSZ electrolyte layer to construct heterointerface between semiconductor and ionic conductor. Study results revealed that the heterointerface between ZnO and YSZ provided a large number of oxygen vacancies. When the mass ratio of YSZ to ZnO was 5:5, the fuel cell achieved the best performance. The maximum power density (P_max) of this fuel cell achieved 721 mW cm^?2 at 550 °C, whereas the P_max of the fuel cell with pure YSZ electrolyte was only 290 mW cm^?2. Further investigation revealed that this composite electrolyte possessed poor O^2? conductivity but good proton conductivity of 0.047 S cm^?1 at 550 °C. The ionic conduction activation energy of 5YSZ-5ZnO composite in fuel cell atmosphere was only 0.62 eV. This work provides an alternative way to improve the ionic conductivity of YSZ-based electrolytes at low operating temperatures.