Modeling of high-efficient direct methanol fuel cells with order-structured catalyst layer

Jiang, Jinghui; Li, Yinshi; Liang, Jiarong; Yang, Weiwei; Li, Xianglin

doi:10.1016/j.apenergy.2019.113431

Cited by 40 publications

(9 citation statements)

References 33 publications

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“…With the concentration of alkaline electrolyte increase, although the diffusion coefficients of metal ions and OH − are reduced in the NaOH and KOH solutions, the diffusion flux of the alkaline electrolyte solution across the membrane can be increased according to Fick's law, which would cause severe mass transfer resistance of oxygen in the cathode electrode. It is known that the structure of the system has a great impact on its performance [28,29]. In order to increase the alkaline resistance of the QAPS membrane, a composite interface model was constructed by adding a layer of polytetrafluoroethylene (PTFE) molecules between the QAPS layer and alkaline electrolyte layer, as shown in Figure 13.…”

Section: Diffusion Process Of Alkaline Electrolyte In Composite Aemmentioning

confidence: 99%

Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane

Song

et al. 2020

Sci. China Technol. Sci.

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During the operation of alkaline direct liquid fuel cells, the alkaline electrolyte is usually needed in the anode electrode to accelerate the electrochemical reaction kinetics of the liquid fuel. However, the crossover of the alkaline solution in the anode through the anion exchange membrane to the cathode can increase the transfer resistance of the oxygen in the cathode. In order to reduce the crossover of the alkaline solution, the diffusion process of the alkaline solution in the anion exchange membrane needs to be fully understood. In this work, interface models of anion exchange membrane-alkaline electrolytes are established based on the cell structure of the quaternary ammonium polysulfone (QAPS) membrane to simulate the dynamic process of the alkaline solution in the membrane. The effect of the type and the concentration of the alkaline solution on the transportation of the metal ions and OH − in the membrane are studied. The results show that the agglomeration of Na + is formed more easily than K + in the interface model. Because of the strong interaction of Na + on OH − , OH − ions appear to be concentrated, resulting in that the diffusion coefficients of the metal ion and OH − in the in Na + solution are lower than those in the K + solution. In addition, with the raised concentration of electrolyte solution, the aggregation degrees of the metal ions and OH − can be increased, which means an enlarged mass transfer resistance of the components. Furthermore, by adding a polytetrafluoroethylene (PTFE) layer on the QAPS membrane, the distribution of metal ions tends to be concentrated, and the number of hydrophilic channels in the QAPS membrane is reduced, which significantly increases the alkali resistance of the anion exchange membrane.direct liquid fuel cells, anion exchange membrane, alkali crossover, QAPS membrane

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Section: Diffusion Process Of Alkaline Electrolyte In Composite Aemmentioning

confidence: 99%

Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane

Song

et al. 2020

Sci. China Technol. Sci.

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“…Its structural design has a significant impact on the current density distribution of the fuel cell. Jiang et al [11] focused on building an orderly structured catalyst layer on an orderly direct methanol fuel cell. The results show that the direct methanol fuel cell with ordered electrodes produces a better cell performance.…”

Section: Introductionmentioning

confidence: 99%

Collaborative Design for Uneven Physical Structures of Multi-Layers in PEMFC

Yang

Chen

Xiao

et al. 2021

WEVJ

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A collaborative design for the uneven distributions of a flow channel, gas diffusion layer porosity and catalyst layer porosity are newly proposed to improve the utilization ratio of the membrane electrode assembly of the proton exchange membrane fuel cell. The effects of the uneven design of the rib width and of the uneven porosity parameters of the cathode and anode gas diffusion layer and catalyst layer on the fuel cell performance were studied in detail. Numerical simulations were designed and implemented for validation. The results show that the fuel cell performance could be improved through the collaborative design of uneven distributions for different layers. The rib width gradually decreasing and the porosity of the cathode gas diffusion layer and the cathode catalyst layer gradually increasing along the fluid flow direction would contribute to a better design compared to the regular even design. The new uneven design can make the fuel penetrate into the catalyst layer in time to participate in the reaction, improve the utilization rate of the membrane electrode assembly, and greatly improve the performance of the fuel cell.

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“…Therefore, early model studies focusing on the kinetics of DMFCs assumed that carbon dioxide was dissolved in liquid [8,9] or neglected the convection of methanol solution and carbon dioxide [10]. Most liquid-gas two-phase models of DMFCs neglected the impact of carbon dioxide [11] or indirectly calculated the mass fraction of carbon dioxide from the mass fractions of other species so that the summary of the total mass fractions equals unity [12][13][14][15]. Only a very small number of models have simulated the CO 2 bubble flow within flow channels [16] and counter flow of carbon dioxide gas and liquid fuel during operation [17].…”

Section: Introductionmentioning

confidence: 99%

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

Metzger

Sekar

et al. 2021

Journal of Electrochemical Energy Conversion and Storage

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The gas flow of carbon dioxide from the catalyst layer (CL) through the micro porous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid-vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about 2-3 orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flow rate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (< 5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To build up high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

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Modeling of high-efficient direct methanol fuel cells with order-structured catalyst layer

Cited by 40 publications

References 33 publications

Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane

Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane

Collaborative Design for Uneven Physical Structures of Multi-Layers in PEMFC

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

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