• 제목/요약/키워드: Cathodes

검색결과 269건 처리시간 0.027초

Materials Chemical Point of View for Durability Issues in Solid Oxide Fuel Cells

  • Yokokawa, Harumi;Horita, Teruhisa;Yamaji, Katsuhiko;Kishimoto, Haruo;Brito, M.E.
    • 한국세라믹학회지
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    • 제47권1호
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    • pp.26-38
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    • 2010
  • Degradation in Solid Oxide Fuel Cell performance can be ascribed to the following fundamental processes from the materials chemical point of view; that is, diffusion in solids and reaction with gaseous impurities. For SOFC materials, diffusion in solids is usually slow in operation temperatures $800\sim1000^{\circ}C$. Even at $800^{\circ}C$, however, a few processes are rapid enough to lead to some degradations; namely, Sr diffusion in doped ceria, cation diffusion in cathode materials, diffusion related with metal corrosion, and sintering of nickel anodes. For gaseous impurities, chromium containing vapors are important to know how the chemical stability of cathode materials is related with degradation of performance. For LSM as the most stable cathode among the perovskite-type cathodes, electrochemical reduction reaction of $CrO_3$(g) at the electrochemically active sites is crucial, whereas the rest of the cathodes have the $SrCrO_4$ formation at the point where cathodes meet with the gases, leading to rather complicated processes to the degradations, depending on the amount and distribution of reacted Cr component. These features can be easily generalized to other impurities in air or to the reaction of nickel anodes with gaseous impurities in anode atmosphere.

Single-cathode와 Dual-cathode로 구성된 미생물연료전지에서 전류발생 향상을 위한 전자수용체로서의 Nitrate와 Ferric ion의 이용 (Use of Nitrate and Ferric Ion as Electron Acceptors in Cathodes to Improve Current Generation in Single-cathode and Dual-cathode Microbial Fuel Cells)

  • 장재경;유영선;김종구;강연구;이은영
    • 한국미생물·생명공학회지
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    • 제40권4호
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    • pp.414-418
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    • 2012
  • 미생물연료전지 운전을 할 때, 전압손실을 감소시키기 위한 다양한 방법들이 시도 되고 있다. 이 연구는 전해질과 저가의 금속이온을 전자수용체로 이용하여 전류발생을 확인하였다. 전해질로 phosphate buffer를 사용한 경우, 공기만 사용하였을 때보다 향상되었으며, 공기의 공급이 없이는 효과가 적은 것으로 나타났다. 전자수용체로 질산염(nitrate)을 사용하였을 때 산소를 공급하지 않았을 때보다 높은 전류발생을 보였으나 공기포화 물을 사용한 경우와 비교하여 전류발생이 향상되지는 않았다. 질산염을 양극부에 적용시에는 음극부와 양극부 모두 폐수처리가 가능한 시스템으로 구성하여 운전한다면 전류발생은 낮으나 서로 다른 폐수를 처리 할 수 있을 것으로 판단된다. 이 연구에서 적용한 3가지 방법 중에서 3가 철이온을 사용하였을 때 전류 발생이 가장 높았으며, 공기를 공급하지 않아도 전류 발생이 높게 유지되는 것으로 나타났다. 이것은 미생물연료전지의 규모를 증대시킬 때 폭기가 필요 없는 시스템을 구축할 수 있어 큰 장점으로 작용할 것으로 판단된다. 따라서 3가 철이온은 지구상에 가장 많은 금속 이온 중 하나로 용해도가 낮으나 저가의 3가 철이온을 잘 이용한다면 양극부 반응속도를 효율적으로 향상 시킬 수 있을 것으로 판단된다.

용융탄산염형 연료전지 대체음극재료인 Co/Ni alloy의 용융염에서의 in situ oxidation/lithiation과 전기화학적인 거동 연구 (In Situ Oxidation/Lithiation and Electrochemical Behavior of CoNi Alloy as Alternative Material for Molten Carbonate Fuel Cell Cathodes)

  • 조은애;류보현;한종희;윤성필;남석우;임태훈;홍성안;김광범
    • 한국전기화학회:학술대회논문집
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    • 한국전기화학회 2002년도 추계총회 및 학술발표회
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    • pp.3-4
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    • 2002
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Study of physical simulation of electrochemical modification of clayey rock

  • Chai, Zhaoyun;Zhang, Yatiao;Scheuermann, Alexander
    • Geomechanics and Engineering
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    • 제11권2호
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    • pp.197-209
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    • 2016
  • Clayey rock has large clay mineral content. When in contact with water, this expands considerably and may present a significant hazard to the stability of the rock in geotechnical engineering applications. This is particularly important in the present work, which focused on mitigating some unwelcomed properties of clayey rock. Changes in its physical properties were simulated by subjecting the rock to a low voltage direct current (DC) using copper, steel and aluminum electrodes. The modified mechanism of the coupled electrical and chemical fields acting on the clayey rock was analyzed. It was concluded that the essence of clayey rock electrochemical modification is the electrokinetic effect of the DC field, together with the coupled hydraulic and electrical potential gradients in fine-grained clayey rock, including ion migration, electrophoresis and electro-osmosis. The aluminum cathodes were corroded and generated gibbsite at the anode; the steel and copper cathodes showed no obvious change. The electrical resistivity and uniaxial compressive strength (UCS) of the modified specimens from the anode, intermediate and cathode zones tended to decrease. Samples taken from these zones showed a positive correlation between electric resistivity and UCS.