An Electrochemical Method to Improve the Performance of Air Cathodes and Methanol Anodes

He, Chunzhi; Qi, Zhiqang; Hollett, Mark; Kaufman, Arthur

doi:10.1149/1.1490715

Cited by 50 publications

(27 citation statements)

References 5 publications

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“…The principle of hydrogen pumping is to improve PEM fuel cell performance by moving hydrogen from one side of the membrane to the other. As a result of this process, electrode catalyst utilization is increased and MEA performance is improved [4]. This is achieved by reducing the overpotential of oxygen reduction.…”

Section: Other Methodsmentioning

confidence: 99%

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Accelerated conditioning for a proton exchange membrane fuel cell

Yuan

Sun

Wang

et al. 2012

Journal of Power Sources

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a b s t r a c tA conditioning process is usually needed for a newly fabricated proton exchange membrane (PEM) fuel cell to be activated. Depending on the membrane electrode assemblies, this process can take hours and even days to complete. To provide for accelerated conditioning techniques that can complete the process in a short time, this paper compares various reported methods to condition a PEM single cell. The major objectives are to identify accelerated conditioning approaches that can significantly reduce the conditioning duration for the existing conditioning regime in an operationally easy manner, and to understand the fundamental principles that govern accelerated conditioning. Various effects investigated include temperature, cycling steps, and cycling frequencies. Other techniques, such as short circuiting, hydrogen pumping, and hot water circulation, are also discussed. For each technique, measurements are taken using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV).Crown

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Section: Other Methodsmentioning

confidence: 99%

“…On-line techniques explored include current control [5,6], potential control [7,8], temperature control [9][10][11], hydrogen pumping [4,12], CO stripping [13], and air braking [14,15]. Off-line methods include electrochemical conditioning of the MEA [16], and steaming or boiling the electrode [17].…”

Section: Introductionmentioning

confidence: 99%

Accelerated conditioning for a proton exchange membrane fuel cell

Yuan

Sun

Wang

et al. 2012

Journal of Power Sources

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“…For anode polarization and EIS, the cathode was fed with humidified H 2 at a rate of 5 sccm and functioned as a dynamic hydrogen electrode ͑DHE͒. 8,[28][29][30] The cathode was also the counter electrode. The anode was fed with methanol and functioned as working electrode.…”

Section: Methodsmentioning

confidence: 99%

Mixed Phase Pt-Ru Catalyst for Direct Methanol Fuel Cell Anode by Flame Aerosol Synthesis

Chakraborty

Bischoff

Chorkendorff

et al. 2005

J. Electrochem. Soc.

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A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst was found to be a mixture of nanocrystalline, mostly unalloyed Pt and an amorphous phase mostly of Ru and to a lesser extent of Pt oxides on top of the crystalline phase. The flame-produced Pt1Ru1 demonstrated similar onset potential but ∼60% higher activity compared to commercially available Pt1Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy.

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confidence: 99%

“…Several methods have been proposed for conditioning of MEAs to achieve a stable and improved performance of DMFCs. [1][2][3][4] In DMFCs as in the case of polymer electrolyte membrane fuel cell ͑PEMFCs͒, sufficient hydration of polymer electrolyte membrane and recast ionomer in the catalyst layer is necessary to obtain stable proton conductivity, and hence the hydration process might require about 24-48 h. For instance, Aricó et al 1 supplied water to both the anode and cathode compartments of a DMFC, and the cell was warmed up stepwise to a maximum operating temperature of 95°C, followed by an operation with the supply of methanol ͑0.5 M͒ and oxygen at a high current for a period of 24 h. Shukla et al 2 collected the polarization curves of DMFCs after hydrating the MEAs for 24 h by circulating a 2 M methanol solution through the anode compartment at 80°C. Scott et al 3 adopted both the above methods.…”

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confidence: 99%

Impedance Analysis on Transient Behavior of DMFC Anodes during Preconditioning Process

Kim

Lee

Hong

et al. 2005

J. Electrochem. Soc.

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Transient behavior of direct methanol fuel cells ͑DMFCs͒ during the preconditioning process has been investigated with a focus on changes manifested in the anode by using an electrochemical impedance spectroscopic analysis. Preconditioning of membrane electrode assembly ͑MEA͒ is essential to achieve maximum cell performance, and the time required to accomplish the conditioning may vary depending on the methods that are adopted. Preconditioning temperature substantially influences the behaviors of MEAs, and room-temperature treatment has been found to be more favorable than high-temperature treatment at 90°C. Application of electric load during the preconditioning process accelerates the hydration of electrolyte and thus reduces the time required to reach a maximum performance limit. The anode impedance data of DMFC has been deconvoluted by using an equivalent circuit to investigate three kinds of resistances in the MEA, such as resistance of charge transfer ͑R ct ͒, electrolytes ͑R e ͒, and pore electrolytes ͑R p ͒. The underpinning mechanism which causes the change in performance during the preconditioning process is discussed in terms of the changes in the resistance elements of the anode. In recent times, intense research interest has been channeled in improving the performance of direct methanol fuel cells ͑DMFCs͒ based on polymer electrolyte membranes. Performance of a DMFC is strongly influenced not only by the fabrication procedure of membrane electrode assembly ͑MEA͒ but also by the preconditioning method adopted. Hence, to improve the performance of DMFCs, it is important to establish an appropriate conditioning method for MEAs. Several methods have been proposed for conditioning of MEAs to achieve a stable and improved performance of DMFCs. [1][2][3][4] In DMFCs as in the case of polymer electrolyte membrane fuel cell ͑PEMFCs͒, sufficient hydration of polymer electrolyte membrane and recast ionomer in the catalyst layer is necessary to obtain stable proton conductivity, and hence the hydration process might require about 24-48 h. For instance, Aricó et al.1 supplied water to both the anode and cathode compartments of a DMFC, and the cell was warmed up stepwise to a maximum operating temperature of 95°C, followed by an operation with the supply of methanol ͑0.5 M͒ and oxygen at a high current for a period of 24 h. Shukla et al. 2 collected the polarization curves of DMFCs after hydrating the MEAs for 24 h by circulating a 2 M methanol solution through the anode compartment at 80°C. Scott et al. 3 adopted both the above methods.They 4 suggested that hydrogen evolution on electrodes could influence the performance of DMFCs by reducing the overpotential of both oxygen reduction as well as methanol oxidation reactions. Though various routes have been employed for conditioning MEAs, to the best of our knowledge, no definite explanation has been offered in the literature on the mechanism of performance changes that occur during the conditioning period, except a brief mention in our previous study. 5Our presen...

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An Electrochemical Method to Improve the Performance of Air Cathodes and Methanol Anodes

Cited by 50 publications

References 5 publications

Accelerated conditioning for a proton exchange membrane fuel cell

Accelerated conditioning for a proton exchange membrane fuel cell

Mixed Phase Pt-Ru Catalyst for Direct Methanol Fuel Cell Anode by Flame Aerosol Synthesis

Impedance Analysis on Transient Behavior of DMFC Anodes during Preconditioning Process

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