Limiting current behaviour of the direct methanol fuel cell

Scott, Keith; Taama, W.M.; Kramer, Stephanie N.; Argyropoulos, P.; Sundmacher, Kai

doi:10.1016/s0013-4686(99)00285-6

Cited by 94 publications

(63 citation statements)

References 15 publications

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“…The kinetic parameters were selected from the paper of Shivhare et al [7]. As shown in Figure 2, the simulated polarisation curves were obtained by using two groups of thicknesses and specific areas of the catalyst layer selected from literatures [7,10,11,15,[21][22][23]27]. Figure 2 indicates that the simulated polarisation curves show good agreement with the experimental data at lower bulk concentration, lower operating temperature, and lower overpotential.…”

Section: Model Validationmentioning

confidence: 70%

“…It was possible for nucleation of carbon dioxide to take place in diffusion layer or limited to a partial region of the catalyst layer by choosing appropriate operating condition [21,22].…”

Section: Mathematical Modelmentioning

confidence: 99%

“…The simulations over-predict the current densities of the fuel cell at the higher temperature, and methanol concentration in comparison to experimental data. This may be due to liberation of carbon dioxide bubbles, which were generated by the increased electrochemical reaction and tem- 3.4 [10,11,21] perature (lower solubility), limiting methanol transfer from the bulk into the porous catalyst layer.…”

Section: Model Validationmentioning

confidence: 99%

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Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Lü

Scott

Sun

2011

International Journal of Electrochemistry

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An intrinsic time-dependent one-dimensional (1D) model and a macro two-dimensional (2D) model for the anode of the direct methanol fuel cell (DMFC) are presented. The two models are based on the dual-site mechanism, which includes the coverage of intermediate species of methanol, OH, and CO (θ M , θ OH,Ru , and θ CO,Pt ) on the surface of Pt and Ru. The intrinsic 1D model focused on the analysis of the effects of operating temperature, methanol concentration, and overpotential on the transient response. The macro 2D model emphasises the dimensionless distributions of methanol concentration, overpotential and current density in the catalyst layer which were affected by physical parameters such as thickness, specific area, and operating conditions such as temperature, bulk methanol concentration, and overpotential. The models were developed and solved in the PDEs module of COMSOL Multiphysics, giving good agreement with experimental data. The dimensionless distributions of methanol concentration, overpotential, and current density and the efficiency factor were calculated quantitatively. The models can be used to give accurate simulations for the polarisations of methanol fuel cell.

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Section: Model Validationmentioning

confidence: 70%

“…It was possible for nucleation of carbon dioxide to take place in diffusion layer or limited to a partial region of the catalyst layer by choosing appropriate operating condition [21,22].…”

Section: Mathematical Modelmentioning

confidence: 99%

Section: Model Validationmentioning

confidence: 99%

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Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Lü

Scott

Sun

2011

International Journal of Electrochemistry

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“…The parasitic flow of reactant through the membrane can be calculated by adding the following terms, the first one related to diffusion, the other one related to electro-osmotic drag: (7) where is the methanol concentration at the CCL. The current density at the anode in (6) is related to the activation voltage overpotential at the anode by the Butler-Volmer equation [6], as (8) where , are the reference current density and the reference concentration at the anode, respectively. The voltage overpotential is required to overcome the activation energy of the electrochemical reaction on the catalytic surface, and is associated to an energy loss.…”

Section: Analytical Solution Of the Cell Voltagementioning

confidence: 99%

“…The reaction kinetic depends on temperature, according to (8). Consequently, the fuel cell system is described more accurately by a fully non-linear coupled model.…”

Section: Analytical Solution Of the Cell Voltagementioning

confidence: 99%

Two-dimensional analytical modelling of passive-feed direct methanol fuel cells

Alotto¹,

Guarnieri²,

Moro³

2024

RE&PQJ

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Abstract. Direct methanol fuel cells are regarded nowadays as promising energy sources for portable electronic devices. Numerical models can be very useful for addressing the exploration of the fuel cell performance, without the development of many prototypes, which can be very expensive due to the presence of rear materials. Analytical models are particularly suited for investigating the cell performance with limited computing costs.In this work, a two-dimensional model for assessing the performance of an active-feed direct methanol fuel cell is presented, accounting for electrochemical reactions, mass and heat transfer.

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Methanol effects on theO₂reduction reaction

Gilman

Chu

2010

Handbook of Fuel Cells

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The present most advanced technology for direct methanol fuel cell systems is based on proton exchange membrane technology. The membrane/electrode assembly is normally comprised of a sulfonated perfluorinated hydrocarbon membrane that acts as both the electrolyte and mechanical support for the anode and cathode electrodes. The cathode is usually fabricated using Pt black or Pt supported on carbon as the electrocatalyst. The operating temperature is usually well below 100 °C, to minimize vaporization of fuel and water. While this construction offers many advantages, including an invariant, immobile high conductivity electrolyte and very compact cells and cell stacks, it presents disadvantages relating to high permeability of methanol through present available membranes. Methanol permeating through the membrane is usually reported as completely oxidized at the Pt‐based cathode. Permeation of methanol occurs by a combination of thermal diffusion and osmosis and can be equivalent to upwards of 100 mA cm −2 of methanol oxidation current. From the practical point of view, methanol permeation is objectionable because it both wastes fuel and depresses the cathode potential. At the oxygen/air cathode, oxygen reduction and methanol oxidation occur simultaneously. For a simple “mixed potential” effect, the two partial currents would have the same magnitude at any potential as they would if fed to the electrode separately. That is, the cathodic overvoltage would increase to an extent corresponding to an increase in current density corresponding to the partial methanol oxidation current. In the actual practical situation, there is an additional increase in overvoltage of ∼50 mV that appears to correspond to poisoning of the electrocatalyst by methanol adsorbate. There are a number of approaches that have been pursued to reduce the “methanol effect”. Using dilute fuel and operating a fuel cell at high anodic current densities (causing some concentration polarization) can greatly reduce permeation, but with an increase in system complexity. A number of new or composite ion membranes have been explored. So far, reduced permeation has also been accompanied by lower conductivity, poorer mechanical strength or higher electrode polarization. Perhaps the most promising approach involves the development of methanol tolerant electrocatalysts, that are based on porphyrins, chevrel‐phase compounds and other transition metal chalcogenides, some of which appear to approach the catalytic efficiency of Pt. Establishment of long‐term chemical/electrochemical stability of such materials could provide the best solution to the problem of “methanol effects”.

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Limiting current behaviour of the direct methanol fuel cell

Cited by 94 publications

References 15 publications

Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Two-dimensional analytical modelling of passive-feed direct methanol fuel cells

Methanol effects on theO₂reduction reaction

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Limiting current behaviour of the direct methanol fuel cell

Cited by 94 publications

References 15 publications

Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Transient Response and Steady-State Analysis of the Anode of Direct Methanol Fuel Cells Based on Dual-Site Kinetics

Two-dimensional analytical modelling of passive-feed direct methanol fuel cells

Methanol effects on theO2reduction reaction

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Methanol effects on theO₂reduction reaction