两种不同结构中温固体氧化物燃料电池阴极材料的性能研究

发布时间：2018-01-29 19:06

本文关键词： 固体氧化物燃料电池双钙钛矿结构 K_2NiF_4型结构阴极稳定性热膨胀电导率电化学性能　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：固体氧化物燃料电池(SOFC)是一种绿色高效的发电装置,具有非常好的发展前景。与传统的高温SOFC技术相比,IT-SOFC有很多优点,目前发展的主流已经慢慢转移到IT-SOFC技术上。所以,研究与开发可以应用在IT-SOFC上的新型阴极材料是当前研究的主要方向之一。采用固相法合成了单相双钙钛矿结构氧化物Sr_2Co_(1-x )Ti_xFeO_(5+δ)(SCTF,x=0.2,0.4,0.6,0.8)。它们均为立方晶系,空间群为Pm-3m,δ值分别为0.37,0.43和0.48,且均与常用电解质材料在950oC下具有良好的化学兼容性。x=0.2与x=0.4样品在高温下出现了Co的α脱附峰,Fe的α脱附峰以及Co的β脱附峰;x=0.6与x=0.8样品则只观察到了Fe的α脱附峰和Co的β脱附峰,无Co的α脱附峰出现。热重与热膨胀测试结果表明,无自旋态转变Ti~(4+)的引入改变了样品中过渡金属离子的价态分布,提高了SCTF的稳定性,同时降低了SCTF的热膨胀系数。电导率测试结果表明,SCTF(x=0.2,0.4,0.6,0.8)样品最大电导率分别为95.5S cm~(-1)(350oC),44.7Scm~(-1)(375oC),24.1Scm~(-1)(400oC)和7.5 S cm~(-1)(475oC)。800oC时SCTF(x=0.2,0.4,0.6,0.8)阴极在SDC电解质上的ASR值分别为0.040Ωcm~2,0.043Ωcm~2,0.052Ωcm~2和0.069Ωcm~2;以SCTF(x=0.2,0.4,0.6,0.8)为阴极,NiO-SDC为阳极,SDC电解质为支撑的单电池,最大功率密度分别为402 m W cm~(-2),332 m W cm~(-2),293 m W cm~(-2)和225 m W cm~(-2),Ti的引入降低了材料的电化学性能。综上所述,对Sr_2CoFeO_(5+δ)材料进行B位掺杂Ti,成功的降低了其热膨胀系数,提高了稳定性,但是对材料的电学性能和电化学性能产生了一定的负面影响,SCTF(x=0.2,0.4,0.6)系列材料有潜力作为IT-SOFC的阴极候选材料。采用固相法合成了单相K_2NiF_4型结构的(LaSr)_xCoO_(4+δ)(x=1,0.95)金属氧化物材料。该材料为四方晶系,空间群为I4/mmm,且与常用电解质材料在950oC下具有良好的化学兼容性。(LaSr)_xCoO_(4+δ)(x=1,0.95)样品在30oC-1000oC温度范围内的失重百分比分别为0.42%和0.22%,平均热膨胀系数分别为15.2×10~(-6)K~(-1)和16.2×10~(-6) K~(-1),证明LSC材料热稳定性良好,热膨胀系数比较接近常用电解质材料的热膨胀系数。A位缺位的引入进一步提高了材料的稳定性,而样品的热膨胀系数则略微增大。电导率测试结果表明,(LaSr)_xCoO_(4+δ)(x=1,0.95)样品最大电导率分别为202Scm~(-1)(850oC)和182Scm~(-1)(850oC),导电性能良好,满足IT-SOFC阴极材料电导率的要求。800oC时(LaSr)_xCoO_(4+δ)(x=1,0.95)阴极在LSGM电解质上的ASR值分别为0.143Ωcm~2和0.097Ωcm~2。以(LaSr)x CoO_(4+δ)(x=1,0.95)为阴极,NiO-SDC为阳极,LSGM电解质为支撑的单电池,最大功率密度分别为386mWcm~(-2)和463mWcm~(-2),A位缺位的引入改善了材料的电化学性能。综上所述,LaSrCoO_(4+δ)样品电学性能和热学性能优良,但是其电化学性能不佳,需要优化。所以,我们在LaSrCoO_(4+δ)材料中引入A位缺位,降低了其界面阻抗,提高了单电池的输出功率密度,明显改善了电化学性能。
[Abstract]:Solid oxide fuel cell (SOFC) is a kind of green and efficient power generation device, which has a good development prospect. Compared with the traditional high-temperature SOFC technology, IT-SOFC has many advantages. At present, the mainstream of development has gradually shifted to IT-SOFC technology. Research and development of new cathode materials that can be used in IT-SOFC is one of the main research directions at present. Single phase double perovskite structure oxide Sr_2Co_(1-x has been synthesized by solid phase method. Ti_xFeO_(5 未. They all belong to cubic system, space group is Pm-3mand 未 values are 0.37 ~ 0.43 and 0.48, respectively. In addition, the 伪 -desorption peaks of Co were observed at high temperature for both samples with good chemical compatibility with common electrolytes at 950oC. The 伪 desorption peak of Fe and the 尾 desorption peak of Co; The 伪 -desorption peaks of Fe and 尾 -desorption peaks of Co were observed only in the samples of 0.6 and 0.8, and the 伪 -desorption peaks of no Co were observed. The results of thermogravimetric and thermal expansion tests showed that the 伪 -desorption peaks of Fe and Co were observed. The introduction of Ti~(4) changed the valence distribution of transition metal ions and improved the stability of SCTF. At the same time, the thermal expansion coefficient of SCTF was reduced. The maximum conductivities of the samples were 95.5 S cm ~ (-1) ~ 350oC ~ (-1) ~ (44.7Scm ~ (-1)) ~ (375oC), respectively. 24.1 ScmC-1 (400oC) and 7.5ScmC1 (475oC0. 800oC). The ASR values of the cathode on SDC electrolyte are 0.040 惟 cm ~ (-1) 20.043 惟路cm ~ (-1) ~ 20.052 惟 cm~2 and 0.069 惟 cm ~ (2) ~ (2), respectively. The single cell supported by the electrolyte of SDC is NiO-SDC. The maximum power density is 402 MW / cm ~ (2) and 332 MW / cm ~ (-2) respectively. The introduction of 293MW / cm ~ (-2) and 225MW / cm ~ (2 +) Ti reduced the electrochemical properties of the materials. The thermal expansion coefficient of Sr_2CoFeO_(5 未 is reduced and the stability is improved by doping Ti in B site. However, there are some negative effects on the electrical and electrochemical properties of the materials. (0.6) A series of materials have the potential to be cathode candidates for IT-SOFC. The single-phase K _ S _ 2NiF _ s _ 4 structure has been synthesized by solid state method. X1. The material is tetragonal and the space group is I4 / mmm. And it has good chemical compatibility with common electrolyte materials at 950oC. The percentage of weight loss in the temperature range of 30oC-1000oC was 0.42% and 0.22%, respectively. The average coefficient of thermal expansion is 15.2 脳 10 ~ (-1) and 16.2 脳 10 ~ (-1) respectively, which indicates that the thermal stability of LSC is good. The thermal expansion coefficient is close to that of the common electrolyte material. The introduction of the vacancy of position A further improves the stability of the material, while the thermal expansion coefficient of the sample increases slightly. The results of conductivity test show that the thermal expansion coefficient of the sample is similar to that of the electrolyte material. LaSrMr. XCoO\\\. The maximum electrical conductivities of the samples are 2022 ScmC-1 (850oC) and 182ScmP- (850oC), respectively, and the conductivity of the samples is good. The electrical conductivity of IT-SOFC cathode material is satisfied with the requirement of. 800oC. The ASR values of cathode on LSGM electrolyte are 0.143 惟 cm~2 and 0.097 惟 cm ~ (2), respectively. The maximum power density of a single cell supported by cathode NiO-SDC and anode LSGM electrolyte is 386mW / cm ~ (-2) and 463 MW / cm ~ (-2) respectively. The introduction of A vacancy improves the electrochemical performance of the material. In summary, the electrical and thermal properties of LaSrCoO4 未) samples are excellent, but their electrochemical properties are poor and need to be optimized. The introduction of A-site vacancy in LaSrCoO_(4 未) material reduces the interface impedance, increases the output power density of single cell, and improves the electrochemical performance.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4

【相似文献】