Up-Scaled Microfluidic Fuel Cells With Porous Flow-Through Electrodes

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
D. Fuerth ◽  
A. Bazylak
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Surface Area ◽  
Electrode Surface ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Carbon Paper ◽  
Platinum Black ◽  
Flow Through ◽  
Microfluidic Fuel Cell

In this work, an experimental microfluidic fuel cell is presented with a novel up-scaled porous electrode architecture that provides higher available surface area compared to conventional microfluidic fuel cells, providing the potential for higher overall power outputs. Our proof-of-concept architecture is an up-scaled flow-through fuel cell with more than nine times the active electrode surface area of the flow-through architecture first proposed by Kjeang et al. (2008, “A Microfluidic Fuel Cell With Flow-Through Porous Electrodes,” J. Am. Chem. Soc., 130, pp. 4000–4006). Formic acid and potassium permanganate were employed as the fuel and oxidant, respectively, both dissolved in a sulfuric acid electrolyte. Platinum black was employed as the catalyst for both anode and cathode, and the performances of carbon-based porous electrodes including cloth, fiber, and foam were compared to that of traditional Toray carbon paper (TGP-H-120). The effects of catalyst loading were investigated in a microfluidic fuel cell containing 80 pores per linear inch carbon foam electrodes. A discussion is also provided of current density normalization techniques via projected electrode surface area and electrode volume, the latter of which is a highly informative means for comparing flow-through architectures.

Carbon Based Electrodes for Upscaling Microfluidic Fuel Cells

2012 ◽  
Author(s):  
D. Fuerth ◽  
A. Bazylak
Keyword(s):  
Fuel Cells ◽  
Surface Area ◽  
Electrode Surface ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Carbon Paper ◽  
Platinum Black ◽  
Active Electrode ◽  
Flow Through ◽  
Carbon Based

In this work, we present an experimental microfluidic fuel cell with a novel up-scaled porous electrode architecture that provides higher overall power output compared to conventional microfluidic fuel cells and a methodology for electrode material evaluation to inform designs for improved performance. Our proof-of-concept architecture is an up-scaled version of a previously presented flow-through cell with more than nine times the active electrode surface area. We employed 0.04M formic acid and 0.01M potassium permanganate as fuel and oxidant, respectively, dissolved in a 1M sulfuric acid electrolyte. Platinum black was employed as the catalyst for both anode and cathode. Carbon based porous electrodes including felt, cloth, fibre, and foam were compared to traditional Toray carbon paper in order to characterize their respective performances. We also discussed current densities normalized by electrode volume, which is appropriate for comparison of flow-through architectures. The traditional method of current normalization by projected electrode surface area is also presented.

Numerical Analysis of the Effect of Different Channel Geometries and Electrode Materials on the Performance of Microfluidic Fuel Cells

2010 ◽  
Author(s):  
Ali Ebrahimi Khabbazi ◽  
Andrew Richards ◽  
Mina Hoorfar
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Laminar Flow ◽  
Power Density ◽  
Porous Electrode ◽  
Pem Fuel Cells ◽  
Porous Electrodes ◽  
Electrochemical Reactions ◽  
Flow Through ◽  
Microfluidic Fuel Cell

A typical microfluidic fuel cell is comprised of a Y- or T-shaped microchannel. The fuel and the oxidant streams are introduced from the two different inlets. The anodic and cathodic flows meet each other at the beginning of the main channel and start to travel together along the channel. Due to the fact that the viscous forces dominate the inertia forces in microchannels, the oxidant and the fuel streams establish a side-by-side co-laminar flow which makes the anolyte and catholyte flow together without turbulent mixing. Laminar flow in microfluidic fuel cells plays the role of the membrane in proton exchange membrane (PEM) fuel cells by maintaining the separation of the fuel and oxidant. This eliminates the need for the membrane and overcomes the membrane-related issues such as the ohmic overpotential and water management which are relevant to PEM fuel cells. In addition to the above advantage, the high surface-to-volume ratio of these micron-scale devices contributes to their high power density. This advantage is due to the fact that the electrochemical reactions in fuel cells are surface-based. The electrodes on which the electrochemical reactions are occurring are installed appropriately on the walls of the channel in a way that reacting flows are restricted to the proper electrodes. Since the flow is laminar the performance of the microfluidic fuel cell significantly depends on the device geometry. In this paper, different channel geometries and different electrode configurations are modeled and their performances are compared through the polarization curves. It has been found that the high aspect ratio provides the largest power density. In this work, the performance of the flow-through porous electrode was also modeled and compared against the conventional non-porous electrode microfluidic fuel cells. The flow-through porous electrode design is based on cross-flow of aqueous vanadium redox species through the electrodes into an exit channel, where the waste solutions meet and establish a co-laminar flow. This co-laminar flow of reacted species facilitates ionic charge transfer in a membraneless configuration. It has been found that the flow-through porous architecture provides an increased active surface area which contributes to a higher power density as opposed to the fuel cells with non-porous electrodes.

Modeling of Microfluidic Fuel Cells With Flow-Through Porous Electrodes

2010 ◽  
Author(s):  
Ali Ebrahimi Khabbazi ◽  
Mina Hoorfar
Keyword(s):  
Fuel Cell ◽  
Solid Phase ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Metal Catalyst ◽  
Redox Species ◽  
Redox Couples ◽  
Flow Through ◽  
Microfluidic Fuel Cell ◽  
Vanadium Redox

This paper presents a modeling of a microfluidic fuel cell with flow-through porous electrodes using vanadium redox couples as the fuel and oxidant. There are advantages associated with the use of vanadium redox species in microfluidic fuel cell: 1) vanadium redox couples have the possibility of producing high open-circuit potential (up to 1.7 V at uniform PH [1]); 2) they have high solubility (up to 5.4 M) which causes more species available to the electrodes; 3) they do not require metal catalyst for electrochemical reactions so the reactions take place on the bare carbon electrodes. This characteristic of the vanadium redox couple make them a great candidate as reactants as they do not need expensive catalyst coatings on the electrodes. The fuel and the oxidant can be brought into contact with the electrode in two different ways: flowing over the electrodes or flowing through the electrodes. In the presented fuel cell design, the vanadium redox species are forced to flow through the porous electrodes. They finally come to meet each other in the middle microchannel and establish a side-by-side co-laminar flow traveling down the channel. In this paper, the effect of the inlet velocity and electrode porosity has been investigated. As it is expected, the higher velocity results in the higher power densities. For the porosity, however, there is an optimum value. In essence, there is a trade-off between the available electrode surface area and electric conductivity of the solid phase (i.e., the porous carbon electrode). The modeling shows that a porous electrode with a 67% porosity results in the highest power output.

Model-based analysis of geometrical effects in microfluidic fuel cell with flow-through porous electrodes

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040022
Author(s):  
Qiang Xu ◽  
Yiyi She ◽  
Li Li
Keyword(s):  
Fuel Cell ◽  
Reaction Rate ◽  
Fluid Velocity ◽  
Porous Electrode ◽  
Three Dimensional ◽  
Porous Electrodes ◽  
Aspect Ratios ◽  
Electrode Length ◽  
Flow Through ◽  
Microfluidic Fuel Cell

Porous electrodes in microfluidic fuel cell (MFC) operate with nonuniform reaction rate. It is intriguing to improve the utilization degree of the porous electrodes. In this work, a three-dimensional computational model is developed for MFC with flow-through porous electrodes. Characteristics of the reaction rate distributions under different electrode geometries are examined. The results show that reaction rate varies noticeably along the electrode width direction, but minimally along the electrode length direction. High reaction rate region locates in the vicinity of the interface between the porous electrode and the middle channel. A relatively high aspect ratio, defined as the ratio of the electrode length to width, is beneficial to improve the utilization degree of the porous electrodes. Yet, concentration losses increase due to the decreased fluid velocity. Considering the cell performance, optimal electrode aspect ratios are derived for the anode and cathode, respectively.

A Microfluidic Fuel Cell with Flow-Through Porous Electrodes

2008 ◽  
Vol 130 (12) ◽  
pp. 4000-4006 ◽  
Author(s):  
Erik Kjeang ◽  
Raphaelle Michel ◽  
David A. Harrington ◽  
Ned Djilali ◽  
David Sinton
Keyword(s):  
Fuel Cell ◽  
Porous Electrodes ◽  
Flow Through ◽  
Microfluidic Fuel Cell

Optimal design of current collectors for microfluidic fuel cell with flow-through porous electrodes: Model and experiment

2017 ◽  
Vol 206 ◽  
pp. 413-424 ◽  
Author(s):  
Li Li ◽  
Wenguang Fan ◽  
Jin Xuan ◽  
Michael K.H. Leung ◽  
Keqing Zheng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Optimal Design ◽  
Porous Electrodes ◽  
Current Collectors ◽  
Flow Through ◽  
Microfluidic Fuel Cell

Effect of Metal Modification to Carbon Paper Anodes on the Performance of Yeast-Based Microbial Fuel Cells Part Ι: In the Case without Exogenous Mediator

2013 ◽  
Vol 534 ◽  
pp. 76-81 ◽  
Author(s):  
Enas Taha Kasem ◽  
Takuya Tsujiguchi ◽  
Nobuyoshi Nakagawa
Keyword(s):  
Electron Transfer ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Thin Layer ◽  
Electrode Surface ◽  
Microbial Fuel Cells ◽  
Yeast Cells ◽  
Carbon Paper ◽  
Electrode Potentials ◽  
Different Thickness

Effect of modification of carbon paper with a thin layer of cobalt or gold on the performance of yeast-based microbial fuel cells was investigated. The modification was conducted by depositing Co or Au thin layer with different thickness, 5 nm and 30 nm, using a sputtering technique. The electrode performance was evaluated by measuring the electrode potentials and the fuel cell power output. The Co modification significantly increased the performance of the fuel cell, while the Au modification inhibited the performance. SEM observation indicated that the adhesion density of the yeast cells on the electrode surface was affected by the metals. It was confirmed that the electron transfer took place through the surface confined species at the mediatorless anode.

Toward Carbon Foam Structures in a Microfluidic Fuel Cell

2011 ◽  
Author(s):  
D. Fuerth ◽  
A. Bazylak
Keyword(s):  
Fuel Cell ◽  
Carbon Foam ◽  
Carbon Paper ◽  
Cell Potential ◽  
Redox Species ◽  
Flow Through ◽  
Microfluidic Fuel Cell ◽  
And Performance ◽  
Future Work ◽  
Vanadium Redox

In this paper, the design and performance of a flow-through microfluidic fuel cell with carbon-based electrodes is presented. Our preliminary results include the use of Toray TGP-H-090 carbon paper as our porous carbon electrodes. The cell exhibited a maximum power density of 0.12 mW/cm2 and an open cell potential of 1.2 V, and a discussion of this performance is provided. The vanadium redox species is employed as fuel (V2+) and oxidant (VO2+) due to its ability to naturally react on bare carbon, eliminating the need for additional catalysts. Our future work will include the investigation of carbon foam electrodes with grades of 45, 80, and 100 pores per linear inch (PPI).

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