一些无钴和钴基钙钛矿结构中温固体氧化物燃料电池阴极材料的制备与性能研究

发布时间：2018-06-23 14:16

本文选题：中温固体氧化物燃料电池 + 钙钛矿　；参考：《吉林大学》2014年博士论文

【摘要】：固体氧化物燃料电池(SOFC)作为一种清洁高效的能源转换装置，受到人们的广泛关注和研究。传统的SOFC研究中，通常使用La1xSrxMnO3(LSM)氧化物作为SOFC的阴极材料。LSM阴极材料与传统的电解质材料YSZ热兼容，只有在800-1000C的高温环境下才能表现出稳定优良的电学和电化学性能。当SOFC的工作温度下降到600-800C的中温范围以后，该类传统阴极材料的氧离子传导性能和催化活性会极大地降低，成为限制中温固体氧化物燃料电池(IT-SOFC)性能的主要原因。在IT-SOFC阴极材料中，单掺杂和双掺杂的钴基系列钙钛矿阴极材料具有较高的电化学性能，但这类含钴的材料均存在稳定性差，热膨胀系数过高，高制作成本的问题。最近，双钙钛矿阴极材料由于具有较高的电导率和氧空位浓度而在中温范围内表现出比传统阴极材料更优良的电化学性能，其作为有发展前途的IT-SOFC阴极材料备受关注，然而，含钴的双钙钛矿阴极材料仍存在与电解质的热膨胀匹配问题。阴极材料本身的性质对开发高性能IT-SOFC起着极为关键的作用，因此开发中温条件下具有优良电化学性能的阴极材料尤为重要。本文采用传统的固相反应法分别制备了无钴的钙钛矿结构阴极材料Ba0.5Sr0.5Fe0.9Nb0.1O3-，双钙钛矿结构阴极材料YBaCo2-xCuxO5+(x=0.2,0.4,0.6)，无钴双钙钛矿结构阴极材料Ln2MnFeO6-(Ln=La, Pr, Nd, Sm)和AA’MnFeO6-(A=Ca, Sr, Ba; A’=La, Pr)，并对其性能进行了研究。在无钴钙钛矿结构阴极材料Ba0.5Sr0.5Fe0.9Nb0.1O3-(BSFN)的实验研究中，我们对材料的烧结温度，电导率，热膨胀和电化学性能进行了研究，并对比了采用SDC和LSGM电解质的电化学性能。XRD表明，BSFN在空气中1250oC烧结10h可得到单相立方钙钛矿结构的材料。电导率在425C附近发生传导机制的转变，由半导体导电转变为金属导电。在电化学性能的比较中，当采用LSGM电解质时，BSFN阴极材料表现出的极化阻抗值和电池功率密度均比使用SDC电解质时要高，700oC时在SDC和LSGM两种电解质上测得的极化阻抗值分别为0.078和0.062cm2，800oC时单电池BSFN/SDC/Ni-SDC和BSFN/LSGM/SDC/Ni-SDC的最大电池功率密度分别为414和516mW cm2。良好的电化学性能说明该材料可作为IT-SOFC阴极的候选材料。阴极材料YBaCo2-xCuxO5+(x=0.2,0.4,0.6)(YBCC)具有双钙钛矿结构，在实验中表现出优良的电化学性能。我们探究了铜掺杂对该阴极材料性能的影响。结果表明，在950°C烧结20h可获得单相的YBCC，且在低于900°C的温度下与La0.9Sr0.1Ga0.8Mg0.115Co0.085O2.85(LSGMC)电解质具有良好的化学兼容性。随着铜的掺杂量的增加，YBCC的电导率降低，，且在掺杂量达到0.6时样品的电导率规律完全转变为半导体导电。在热膨胀测试中，阴极材料YBCC表现出较低的平均热膨胀系数，在30-900°C温度范围内的约为15×106K1。在电化学性能测试中，铜掺杂为0.2时的样品表现出最好的电化学性能，700°C时极化阻抗值为0.012cm2，800°C时电池最大功率密度达到811mW cm2。为了开发新型无钴双钙钛矿IT-SOFC阴极材料，我们制备和研究了无钴双钙钛矿阴极材料Ln2MnFeO6-(LnMFO)(Ln=La, Pr, Nd, Sm)和AA’MnFeO6-(AA’MF)(A=Ca, Sr, Ba; A’=La, Pr)。在Ln2MnFeO6-(Ln=La, Pr, Nd, Sm)阴极材料的研究中，该材料总体表现出良好的热学性质，在30-1000C的温度范围内平均热膨胀系数为~10×106K1，与常用电解质具有良好的热匹配性，但该材料的电导率与阻抗值相对较低。为了进一步优化Ln2MnFeO6-(Ln=La, Pr, Nd, Sm)材料的电化学性能，我们选取综合性能较好的La2MnFeO6-和Pr2MnFeO6-样品进一步研究，通过在A位掺杂碱土金属元素来优化这两种阴极材料的性能，得到AA’MnFeO6-(A=Ca, Sr, Ba; A’=La, Pr)阴极材料。在AA’MnFeO6-(A=Ca, Sr, Ba; A’=La，Pr)阴极材料的研究中，Ba掺杂样品由于有杂质相产生，因此最终研究样品为A位掺杂Ca和Sr的AA’MnFeO6-(A=Ca, Sr, Ba; A’=La, Pr)阴极材料。通过一系列电学，热学，电化学相关测试，我们发现，与掺杂Ca的材料相比，掺杂Sr的样品SrLaMnFeO6-和SrPrMnFeO6-的电导率增加，极化阻抗值减小，700oC时极化阻抗分别为4.29和4.97cm2，850oC时单电池的功率密度分别为432和392mW cm2。
[Abstract]:As a clean and efficient energy conversion device, the solid oxide fuel cell (SOFC) is widely concerned and studied. In the traditional SOFC study, the La1xSrxMnO3 (LSM) oxide is usually used as the cathode material of the SOFC and the.LSM cathode material is compatible with the traditional electrolyte material YSZ, only in the high temperature environment of 800-1000C. When the working temperature of SOFC drops to the medium temperature range of 600-800C, the oxygen ion conductivity and catalytic activity of this kind of traditional cathode material will be greatly reduced and the main reason for limiting the performance of the medium temperature solid oxide fuel cell (IT-SOFC).
In IT-SOFC cathode materials, single and double doped cobalt based perovskite cathode materials have high electrochemical properties, but these cobalt containing materials have the problems of poor stability, high thermal expansion coefficient and high production cost. Recently, the Double Perovskite Cathode material has high conductivity and oxygen vacancy concentration at middle temperature. The electrochemical performance of IT-SOFC cathode material is better than that of the traditional cathode material. It has attracted much attention as a promising cathode material. However, the dual Perovskite Cathode material with cobalt still exists the problem of matching the thermal expansion of the electrolyte. The properties of the cathode material itself play a crucial role in the development of high performance IT-SOFC. It is particularly important to develop cathode materials with excellent electrochemical performance under moderate temperature.
In this paper, the cobalt free perovskite structure cathode material Ba0.5Sr0.5Fe0.9Nb0.1O3-, the double perovskite structure cathode material YBaCo2-xCuxO5+ (x=0.2,0.4,0.6), the cobalt free perovskite structure cathode material Ln2MnFeO6- (Ln=La, Pr, Nd, Sm) and AA 'MnFeO6- are prepared by the traditional solid state reaction method respectively. The study was done.
In the experimental study of the cobalt free perovskite structure cathode material Ba0.5Sr0.5Fe0.9Nb0.1O3- (BSFN), the sintering temperature, electrical conductivity, thermal expansion and electrochemical properties of the materials were studied. The electrochemical properties of SDC and LSGM electrolytes were compared. The results showed that the single-phase cubic perovskite junction could be obtained by 1250oC sintered 10h in the air of BSFN. The conductivity of the conduction mechanism is changed from semiconductor conduction to metal conduction in the vicinity of 425C. In the comparison of electrochemical properties, when LSGM electrolytes are used, the polarization impedance values and the power density of the BSFN cathode materials are higher than those of the SDC electrolyte, and 700oC is on the SDC and LSGM two electrolytes at the time of 700oC. When the measured polarization impedance values are 0.078 and 0.062cm2800oC, the maximum battery power density of the single cell BSFN/SDC/Ni-SDC and BSFN/LSGM/SDC/Ni-SDC is 414 and 516mW cm2., respectively, indicating that the material can be used as a candidate for the IT-SOFC cathode.
The cathode material YBaCo2-xCuxO5+ (x=0.2,0.4,0.6) (YBCC) has a double perovskite structure and shows excellent electrochemical performance in the experiment. We explore the effect of copper doping on the performance of the cathode material. The results show that the single phase YBCC can be obtained at 950 degree C sintering 20h and La0.9Sr0.1Ga0.8Mg0.115Co0.085O2.85 (L) at a temperature lower than 900 degree C. SGMC) the electrolyte has good chemical compatibility. With the increase of copper doping, the conductivity of YBCC decreases, and the conductivity law of the sample is completely converted to semiconductor conduction when the amount of doping reaches 0.6. In the thermal expansion test, the cathode material YBCC shows a lower average thermal expansion coefficient, which is about 15 in the range of 30-900 C temperature. In the electrochemical performance test of 106K1., the sample with copper doped to 0.2 shows the best electrochemical performance. The maximum power density of the battery is 811mW cm2. when the polarization impedance is 0.012cm2800 degree C at 700 C.
In order to develop new cobalt free perovskite IT-SOFC cathode materials, we have prepared and studied cobalt free Perovskite Cathode material Ln2MnFeO6- (LnMFO) (Ln=La, Pr, Nd, Sm) and AA 'MnFeO6- (AA' MF). In the temperature range of 30-1000C, the average thermal expansion coefficient is ~10 x 106K1, which has good thermal matching with the commonly used electrolyte, but the conductivity and impedance of the material are relatively low. In order to further optimize the electrochemical properties of Ln2MnFeO6- (Ln=La, Pr, Nd, Sm) materials, we choose a better comprehensive performance of La2MnFeO6- and Pr2MnFeO6- samples. In the further study, the properties of the two cathode materials were optimized by doping the alkaline earth metal elements in the A bit, and the cathode materials of AA 'MnFeO6- (A=Ca, Sr, Ba; A' =La, Pr) were obtained.
In the study of AA 'MnFeO6- (A=Ca, Sr, Ba; A' =La, Pr) cathode materials, Ba doped samples are produced because of the impurity phase, so the final research sample is the cathode material for A bit doping Ca and Sr. The conductivity of the samples SrLaMnFeO6- and SrPrMnFeO6- of the mixed Sr increases, the polarization impedance decreases. The power density of the single cell is 432 and 392mW cm2., respectively, when the polarization impedance is 4.29 and 4.97cm2850oC at 700oC, respectively.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM911.4

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