• Title/Summary/Keyword: Cathode

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Effect of Fabrication Method of Cathode on OCV in Enzyme Fuel Cells (효소연료전지의 Cathode 제조조건이 OCV에 미치는 영향)

  • Lee, Se-Hoon;Kim, Young-Sook;Chu, Cheun-Ho;Na, Il-Chai;Lee, Jung-Hoon;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.54 no.2
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    • pp.171-174
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    • 2016
  • Enzyme fuel cells were composed of enzyme cathode and PEMFC anode. Enzyme cathode was fabricated by compression of a mixture of graphite particle, laccase as a enzyme and ABTS as a redox mediator, and then coated with Nafion ionomer. Open circuit voltage (OCV) were measured with variation of cathode manufacture factors, to find optimum condition of enzyme cathode. Optimum pressure was 4.0 bar for enzyme cathode pressing process. Highest OCV was obtained at 95% graphite composition in enzyme cathodee. Optimum glucose concentration was 0.4 mol/l in cathode substrate solution.

Electricity Generation by Microbial Fuel Cell Using Microorganisms as Catalyst in Cathode

  • Jang, Jae Kyung;Kan, Jinjun;Bretschger, Orianna;Gorby, Yuri A.;Hsu, Lewis;Kim, Byung Hong;Nealson, Kenneth H.
    • Journal of Microbiology and Biotechnology
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    • v.23 no.12
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    • pp.1765-1773
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    • 2013
  • The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.

Performance of the PEMFC for the mobile devices according to cathode (Cathode에 따른 휴대용 PEM 연료전지의 성능 변화)

  • Lee, Se-Won;Lee, Kang-In;Park, Min-Soo;Chu, Chong-Nam
    • 한국신재생에너지학회:학술대회논문집
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    • pp.550-553
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    • 2008
  • In this paper, experiments of air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to the cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single cell and 6-cell stack were used in this experiments. The experimental results showed that the open type cathode flow field plate gave better performance for small size PEMFCs because the open type cathode plate allowed better air convection than the channel type cathode plate. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical slit cell. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, PEMFC generated more stable power in the mass transport loss region.

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Emission test of a domestic fabricated cathode with higher current density

  • Ju, Yeong-Do;Gong, Hyeong-Seop;Kim, Seung-Hwan;Tanwar, Anil;Seok, Yeong-Eun;Lee, Byeong-Jun;Hong, Yong-Jun;Sin, Jin-U;So, Jun-Ho
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.205.2-205.2
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    • 2016
  • The emission test a domestic fabricated cathode is conducted using an easy-replaceable-emitter-type test bench. A simple cylindrical button type cathode is dropped vertically into a cathode cup holder. The cathode is heated by a tungsten wire heater located around the cup holder. The cathode temperature is measured by an optical pyrometer. A high voltage pulse power supply gives the anode-cathode gap voltage up to 20 kV with the pulse width of 15 us. The emitted current from the cathode is captured at a faraday cup and is measured using current transformer and oscilloscope. The test bench is installed in the vacuum chamber with easy access door and, therefore, the cathode can be easily replaceable. We confirmed the emission current density of $15A/cm^2$ and $80A/cm^2$ with a domestic fabricated B-type cathode and a Scandate cathode, respectively. The detailed test result for the cathode will be presented.

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Study on Composite Cathode for YSZ Electrolyte in SOFC (SOFC의 YSZ 전해질에 대한 혼합공기극 연구)

  • Lee, Chang-Bo;Bae, Joong-Myeon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.1
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    • pp.62-67
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    • 2007
  • Optimization of cathode properties for intermediate temperature-operating SOFC (IT-SOFC) is carried out by using composite-type electrode structure in this study. Composite cathode may lower cathode overpotential by enhancing mixed ionic-electronic conductivity. In this study, particularly, LSM/YSZ, LSF/YSZ, LSCF/CGO, and PSC/CGO were selected as cathode materials. LSM/YSZ composite cathode showed the best performance of about 0.9${\Omega}cm^2$ at $700^{\circ}C$. It is inferred that the resistance is mainly affected by the reactivity between cathode and electrolyte which can cause the formation of resistive phases. Area specific resistance (ASR) characteristics were not changed significantly with decreasing sintering temperature of cathode, because reaction sites were increased even with worse adhesion of cathode on electrolytes.

The effects of conductivity and CNT cathode on electricity generation in air-cathode microbial fuel cell (공기양극 미생물연료전지 시스템에서 전력발생특성에 미치는 전기전도도와 CNT 양극의 영향)

  • Yoo, Kyu-Seon;Park, Hyun-Soo;Song, Young-Chae;Woo, Jung-Hui;Lee, Chae-Young;Chung, Jae-Woo
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.3
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    • pp.355-360
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    • 2012
  • The characteristics of power generation were investigated by changing the electrical conductivity from 10 to 40mS/cm using air-cathode microbial fuel cell, which had graphite fiber fabric(GFF) anode. There were three kinds of cathode used: one was carbon cloth cathode coated with Pt, another was carbon nanotube(CNT) cathode with non-precious catalyst of Fe-Cu-Mn, and the other was carbon nanotube(CNT) cathode without any catalyst. When it was operated in batch mode, power density of 1369.5mW/$m^2$ was achieved at conductivity of 20mS/cm. Power density from MFC with CNT cathode coated with multi-catalyst of Fe-Cu-Mn was shown about 985.55mW/$m^2$, which was 75.1% compared the power density of carbon cloth coated with Pt. This meant that CNT cathode coated with multi-catalyst of Fe-Cu-Mn could be an alternative of carbon cloth cathode.

A study of the hollow cathode discharge (HOLLOW CATHODE DISCHARGE의 방전 특성 연구)

  • Cho, S.M.;Seo, Y.W.;Kim, M.J.;Whang, K.W.
    • Proceedings of the KIEE Conference
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    • pp.139-141
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    • 1989
  • The characteristics of the hollow cathode discharge were investigated. Temperature distribution of the hollow cathode was investigated and I-V curves of the hollow cathode discharge were obtained. In this paper variables are chamber pressure, Ar gas flow rate injected through the cathode tube and the gap distance between cathode and anode. The inter electrode electron temperature and density were measured by Langmuir probe.

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MF(Multi-Function) Cathode for High Current Density CRT

  • Kim, Tae-Wook;Bae, Min-Cheol;Youn, Young-Jun
    • Journal of Information Display
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    • v.5 no.4
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    • pp.23-26
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    • 2004
  • A limitation of oxide cathode is the high current density, caused by low electrical conductivity of an emitter layer. This limitation can be overcome by increasing the conductivity, and uniform dispersion of Ni powder and pore agent could be achieved by using the screen-printing method. This new cathode has shown not only high current density reliability but also improved performance characteristics and as such given the name "Multi-Function cathode". It is expected to be a good replacement of the impregnated cathode.

The Influence of the Cathode Surface State on the Spark Voltage in the Townsend Discharge Domain (Townsend 방전영역의 불꽃전압에 미치는 음극표면상태의 영향)

  • 백용현
    • 전기의세계
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    • v.28 no.1
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    • pp.73-82
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    • 1979
  • There are a great number of papers on the Townsend discharge in gases, and many of them are concerned with the effect of the cathode. It has been regarded that there are two kinds of effect of the electrodes, especially of the cathode; (a) the effect caused by the difference of the cathode material and (b) the effect by the change of the cathode surface state even in the same material. Both of them may change the secondary coefficient following after the change of the work function, and the atter may further change the primary ionization coefficient as foreign atoms on the surface may be dseorbed in sparks to decrease the purity of the gas. Thus the two effects must be investigated independently to study the roles of the cathode in gas discharges. In this report the effect of the cathode material on the sparking voltage is described. The experiment is also carried out under the condition that the desorption of impurities from the cathode be negligible. From these the new correlativity between the work function of the cathode and the sparking voltage is obtained. In addition, the interesting character of the minimum point of the Paschen's curve can be found.

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Performance of the Small PEMFC according to Cathode (Cathode에 따른 소형 PEM 연료전지의 성능 변화)

  • Lee, Se-Won;Lee, Kang-In;Park, Min-Soo;Chu, Chong-Nam
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.4
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    • pp.283-290
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    • 2008
  • In this paper, experiments with an air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single-cell and 6-cell stack were used in the experiments. The experimental results showed that the open-type cathode flow field plate gave a better performance than the small channel type. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical one. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, the PEMFC generated more stable power in the mass transport loss region. Since stable power in the mass transport region is closely related to the air supply, computational fluid dynamics (CFD) analysis for air-breathing PEMFC of different cathode surface directions was performed.