• Title/Summary/Keyword: MIEC

Search Result 11, Processing Time 0.029 seconds

Electrochemical Evaluation of Mixed Ionic and Electronic Conductor-Proton Conducting Oxide Composite Cathode for Protonic Ceramic Fuel Cells (혼합 이온 및 전자 전도체-프로톤 전도성 전해질 복합 공기극을 적용한 프로토닉 세라믹 연료전지의 전기화학적 성능 평가)

  • HYEONGSIK SHIN;JINWOO LEE;SIHYUK CHOI
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.35 no.1
    • /
    • pp.48-55
    • /
    • 2024
  • The electrochemically active site of mixed ionic and electronic conductor (MIEC) as a cathode material is restricted to the triple phase boundary in protonic ceramic fuel cells (PCFCs) due to the insufficient of proton-conducting properties of MIEC. This study primarily focused on expanding the electrochemically active site by La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF6428)-BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (BZCYYb4411) composite cathode. The electrochemical properties of the composite cathode were evaluated using anode-supported PCFC single cells. In comparison to the LSCF6428 cathode, the peak power density of the LSCF6428-BZCYYb4411 composite cathode is much enhanced by the reduction in both ohmic and non-ohmic resistance, possibly due to the increased electrochemically active site.

Electrochemical Performance of the Solid Oxide Fuel Cell with Different Thicknesses of BSCF-based Cathode (BSCF계 혼합전도성 공기극의 두께에 따른 고체산화물 연료전지의 전기화학적 특성)

  • Jeong, Jaewon;Yoo, Chung-Yul;Joo, Jong Hoon;Yu, Ji Haeng
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.24 no.2
    • /
    • pp.186-192
    • /
    • 2013
  • In order to reduce the costs and to improve the durability of solid oxide fuel cell (SOFC), the operating temperature should be decreased while the power density is maintained as much as possible. However, lowering the operating temperature increases the cathode interfacial polarization resistances dramatically, limiting the performance of low-temperature SOFC at especially purely electronic conducting cathode. To improve cathode performance at low temperature, the number of reaction sites for the oxygen reduction should be increased by using a mixed ionic and electronic conducting (MIEC) material. In this study, anode-supported fuel cells with two different thicknesses of the MIEC cathode were fabricated and tested at various operating temperatures. The anode supported cell with $32.5{\mu}m$-thick BSCFZn-LSCF cathode layer showed much lower polarization resistance than that with $3.2{\mu}m$ thick cahtode and higher power density especially at low temperature. The effects of cathode layer thickness on the electrochemical performance are discussed with analysis of impedance spectra.

Studies of Co-Fe based perovskite cathodes with fixed A-site cations (중 저온형 고체 산화물 연료전지를 Co-Mn 계열의 페로브스카이트 구조의 공기극에 관한 연구)

  • Park, Kwang-Jin;Kim, Jung-Hyun;Bae, Joong-Myeon
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2006.11a
    • /
    • pp.364-367
    • /
    • 2006
  • The decrease of polarization resistance in cathode is the key point for intermediate temperature SOFC(Solid Oxide Fuel Cell). In this study, the Influence of Co substitution in B-site at perovskite PSCM (Pr0.3Sr0.7CoxMn(1-x)) was investigated. The PSCM series exhibits excellent MIEC(Mixed ionic Electronic Conductor) properties. The ASR(Area Specific Resistance) of PSCM3773 was $0.174{\Omega}cm^2\;at\;700^{\circ}C$. The activation energy of PSCM3773 was also lower than other compositions of PSCM. The ASR values were increased gradually during the thermal cycling test of PSCM37773 due to the delamination between electrolyte and cathode materials.

  • PDF

Study of $Pr_{0.3}Sr_{0.7}CO_{x}Fe_{(1-x)}O_{3-\delta}$ (x=0, 0.3, 0.5, 0.7, 1) as the cathode materials for intermediate temperature SOFC (${\cdot}$저온형 고체 산화물 연료전지의 공기극 물질로 사용되는 $Pr_{0.3}Sr_{0.7}CO_{x}Fe_{(1-x)}O_{3-\delta}$ (x=0, 0.3, 0.5, 0.7, 1) 에 관한 연구)

  • Park, Kwang-Jin;Kim, Jung-Hyun;Lee, Chang-Bo;Bae, Joong-Myeon
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2007.06a
    • /
    • pp.125-128
    • /
    • 2007
  • The influence of Co substitution in B-site at perovskite PSCF($Pr_{0.3}Sr_{0.7}CO_{x}Fe_{(1-x)}O_{3}$) was investigated in this study. The PSCF series exhibits excellent MIEC(mixed ionic electronic conductor) properties. ASR(area specific resistance) of PSCF3737 was 0.137 ${\Omega}{\cdot}cm^{2}$ at $700^{\circ}C$. The activation energy of PSCF3737 was also lower than other compositions of PSCF. ASR of PSCF3737 was analysed as two parts at different part of frequency region. Responses at middle frequency part (${\sim}10^2$ Hz) were concerned with oxygen reduction reaction and those at low frequency part (${\sim}10^{-1}$ Hz) were related with oxygen diffusion.

  • PDF

Cathode Properties of Sm-Sr-(Co,Fe,Ni)-O System with Perovskite and Spinel Structures for Solid Oxide Fuel Cell (고체산화물 연료전지의 페로브스카이트와 스피넬 구조를 갖는 Sm-Sr-(Co,Fe,Ni)-O 시스템의 공기극 특성)

  • Baek, Seung-Wook;Kim, Jung-Hyun;Baek, Seung-Whan;Bae, Joong-Myeon
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2007.06a
    • /
    • pp.133-136
    • /
    • 2007
  • Perovskite-structured samarium strontium cobaltite (SSC), which is mixed ionic electronic conductor (MIEC), is considered as a promising cathode material for intermediate temperature-operating solid oxide fuel cell (SOFC) due to its high electrocatalytic property. Cathode material containing cobalt (Co) is unstable at high temperature and has a relatively high thermal expansion property. In this paper, Sm-Sr-(Co,Fe,Ni)-O system with perovskite and spinel structures was investigated in terms of electrochemical property and thermal expansion property, respectively. Area specific resistance (ASR) was measured by ac impedance spectroscopy to investigate the electrochemical property of cathode, and thermal expansion coefficient (TEC) was measured by using dilatometer. Micro structure of cathode was observed by scanning electron microscopy. Perovskite-structured $Sm_{0.5}Sr_{0.5}CoO_{3-\delta}$ showed the ASR of $0.87{\Omega}/cm^{2}$, and $Sm_{0.5}Sr_{0.5}NiO_{3-\delta}$, which actually has a spinel structure, showed the lowest TEC value of $13.3{\times}10^{-6}/K$.

  • PDF

Sulfur Tolerance Effects on Sr0.92Y0.08Ti0.5Fe0.5O3-δ as an Alternative Anode in Solid Oxide Fuel Cells

  • Kim, Jun Ho;Yun, Jeong Woo
    • Journal of Electrochemical Science and Technology
    • /
    • v.9 no.2
    • /
    • pp.133-140
    • /
    • 2018
  • $Sr_{0.92}Y_{0.08}Ti_{0.5}Fe_{0.5}O_{3-{\delta}}$ (SYTF0.5) is investigated as an alternative anode in $H_2$ fuels containing $H_2S$ (0-200 ppm). Although additional ionic conductivity is introduced by aliovalent substitution of $Ti^{4+}$ by $Fe^{3+}$ in the B-site, the SYTF0.5 has lower electrical conductivity than that of the $Sr_{0.92}Y_{0.08}TiO_{3-{\delta}}$. Due to the mixed ionic and electronic conductive (MIEC) property exhibited in the SYTF0.5 anode, the electrochemical performance of the SYTF0.5 anode is improved, as well as the sulfur tolerance. The maximum power densities in $H_2$ at $900^{\circ}C$ for the SYT anode and the SYTF0.5 anode were 56.9 and $98.6mW/cm^2$, respectively. The maximum power density in the SYTF0.5 anode at 200 ppm of $H_2S$ concentration decreased by only 12.9% (86.3 to $75.2mW/cm^2$).

Study of Pr0.3Sr0.7CoxMn(1-x)O3 as the Cathode Materials for Intermediate Temperature SOFC (중.저온형 고체 산화물 연료전지의 공기극 물질로 사용되는 Pr0.3Sr0.7CoxMn(1-x)O3 (x=0, 0.3, 0.5, 0.7, 1)에 관한 연구)

  • Park, Kwang-Jin;Kim, Jung-Hyun;Bae, Joong-Myeon
    • Journal of the Korean Ceramic Society
    • /
    • v.44 no.4 s.299
    • /
    • pp.214-218
    • /
    • 2007
  • The decrease of polarization resistance in cathode is the key point for operating at intermediate temperature SOFC (solid oxide fuel cell). In this study, the influence of Co substitution in B-site at complex perovskite on the electronic conductivity of PSCM ($Pr_{0.3}Sr_{0.7}Co_xMn_{(1-x)}$) was investigated. The PSCM series exhibits excellent MIEC (mixed ionic electronic conductor) properties. The ASR (area specific resistance) of PSCM3773 was $0.174{\Omega}{\cdot}cm^2\;at\;700^{\circ}C$. The activation energy of PSCM3773 was also lower than other compositions of PSCM. The TEC(thermal expansion coefficient) was decreased by addition of Mn. The ASR values were increased gradually during the thermal cycling test of PSCM37773 due to the delamination between electrolyte and cathode materials. The delamination was caused by the difference of TEC.

Effect of B-Cation Doping on Oxygen Vacancy Formation and Migration in LaBO3: A Density Functional Theory Study

  • Kwon, Hyunguk;Park, Jinwoo;Kim, Byung-Kook;Han, Jeong Woo
    • Journal of the Korean Ceramic Society
    • /
    • v.52 no.5
    • /
    • pp.331-337
    • /
    • 2015
  • $LaBO_3$ (B = Cr, Mn, Fe, Co, and Ni) perovskites, the most common perovskite-type mixed ionic-electronic conductors (MIECs), are promising candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The catalytic activity on MIEC-based cathodes is closely related to the bulk ionic conductivity. Doping B-site cations with other metals may be one way to enhance the ionic conductivity, which would also be sensitively influenced by the chemical composition of the dopants. Here, using density functional theory (DFT) calculations, we quantitatively assess the activation energies of bulk oxide ion diffusion in $LaBO_3$ perovskites with a wide range of combinations of B-site cations by calculating the oxygen vacancy formation and migration energies. Our results show that bulk oxide ion diffusion dominantly depends on oxygen vacancy formation energy rather than on the migration energy. As a result, we suggest that the late transition metal-based perovskites have relatively low oxygen vacancy formation energies, and thereby exhibit low activation energy barriers. Our results will provide useful insight into the design of new cathode materials with better performance.

Oxygen Permeation and Mechanical Properties of La0.6Sr0.4Co0.2Fe0.8O3-δ Membrane with Different Microstructures (미세구조에 따른 La0.6Sr0.4Co0.2Fe0.8O3-δ 분리막의 산소투과 및 기계적 특성)

  • Lee, Shi-Woo;Lee, Seung-Young;Lee, Kee-Sung;Woo, Sang-Kuk;Kim, Do-Kyung
    • Journal of the Korean Ceramic Society
    • /
    • v.39 no.10
    • /
    • pp.994-1000
    • /
    • 2002
  • Oxygen permeability and the mechanical properties of mixed ionic-electronic conductive $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ perovskite-type membrane, fabricated by solid state reaction, were investigated with regard to microstructure. The microstructure of the membrane was controlled by changing the sintering temperature and holding time. The average grain size and relative density were evaluated as a function of sintering conditions. As the fraction of grain boundary decreased, oxygen permeability showed a tendency to increase. Especially the maximum oxygen flux of 0.37 ml/$cm^2$${\cdot}$min was measured for the specimen sintered at 1300${\circ}C$ for 10 h, which has high density and relatively large grain size. Fracture strength was dependent on the relative density of sintered body, while fracture toughness increased with average grain size.

Study of Optimization and Characteristics of PSCF3737(Pr0.3Sr0.7Co0.3Fe0.7O3) for IT-SOFC (중저온형 SOFC를 위한 PSCF3737(Pr0.3Sr0.7Co0.3Fe0.7O3) 공기극 물질의 특성 및 최적화께 관한 연구)

  • Park, Kwang-Jin;Lee, Chang-Bo;Kim, Jung-Hyun;Baek, Seung-Wook;Bae, Joong-Myeon
    • Journal of the Korean Electrochemical Society
    • /
    • v.10 no.3
    • /
    • pp.207-212
    • /
    • 2007
  • [ $PSCF3737(Pr_{0.3}Sr_{0.7}Co_{0.3}Fe_{0.7}O_3)$ ] is a good candidate cathode material for IT-SOFC(intermediate temperature solid oxide fuel cell) because of high MIEC(mixed ionic electronic conductor) conductivity. In this study, the characteristics of PSCF3737 was investigated and optimizations of sintering temperature and thickness for $PSCF3737(Pr_{0.3}Sr_{0.7}Co_{0.3}Fe_{0.7}O_3)$ was carried out. Impedance responses were divided into two parts by frequency region. Middle frequency part (${\sim}10^2\;Hz$) was concerned with oxygen reduction reaction on surface and low frequency part (${\sim}10^{-1}\;Hz$) was related with oxygen diffusion. The reasonable sintering temperature and thickness of cathode were $1200^{\circ}C$ and about $27\;{\mu}m$ with regard to EIS(electrochemical impedance spectroscopy). ASR(areas specific resistance) of optimized cathode is $0.115\;{\Omega}\;cm^2$ at $700^{\circ}C$.