Upscaling of microfluidic fuel cell using planar single stacks

Abstract

Summary The commercialization of microfluidic fuel cells remains difficult because of their low‐power density. In this study, microfluidic fuel cells with a planar single‐stack structure are proposed to improve the power density. The proposed stacks connect multiple cells in series, parallel, series–parallel, and parallel–series configurations. The electrolyte flow patterns of the stacks were numerically analyzed, and cell performances were experimentally measured with a platinum electrode using formic acid as the fuel. With a minimum size, these planar cell single stacks provide better power density than a single cell. The cell stack connected in parallel and then in series, where the velocity and pressure distributions of the electrolytes were simulated as almost uniform and few inner electrical connections existed, produced the best scaling‐up efficiency of 1.93. Additionally, a common feed inlet configuration was developed to further reduce the size of the cell stack further. The results show that well‐balanced fluid flow between inlets is necessary to obtain high scalability.

Recent advances in electrocatalysts, mechanism, and cell architecture for direct formic acid fuel cells

“…(Reprinted with permission (through Copyright Clearance Central) from reference (Moreno‐Zuria et al, 2014) Copyright © 2014, Elsevier); (f) A schematic illustration representing a microfluidic cell with cylindrical array anodes to tackle the perturbance generated at the co‐laminar interface due to product CO 2 generation. (Reprinted with permission (through Copyright Clearance Central) from reference (Zhu et al, 2014) Copyright © 2013, Elsevier); (g) Various combinations of planar single stacks in (A) four‐series, (B) four‐parallel, (C) two‐series and then two‐parallel, and (D) two‐parallel and then two‐series (Reprinted with permission (through Copyright Clearance Central) from reference (S. H. Lee & Ahn, 2019) Copyright © 2019, John Wiley & Sons, Ltd.); (h) Comparison of a paper based microfluidic fuel cell and a commercial lateral flow test strip for dengue diagnosis. (Reprinted with permission (through Copyright Clearance Central) from reference (Esquivel et al, 2014) Copyright © 2014, The Royal Society of Chemistry); (i) Schematic illustration of single‐inlet paper‐pencil fuel cell.…”

“…For a cell using FA as the fuel and potassium permanganate as the oxidant, the peak power and scaling‐up efficiency of the mixed connections were better than series or parallel connections. The size of the stack was further reduced by designing a common‐feed inlet stream to unify the fuel inlets and oxidant inlets as two single inlet streams (S. H. Lee & Ahn, 2019).…”

Boost performance of porous electrode for microfluidic fuel cells: electrochemical modification or structure optimization?

“…[15][16][17] By now, extensive studies have been reported to boost the MFC output with various methods, including the introduction of innovative channel geometries, 10,18,19 the design of novel electrode configurations, 20,21 the development of robust catalysts, 22 the use of different redox chemistry, 9,23,24 the application of hydrodynamic focusing technology 25 and the implementation of the stack strategy. 5,26,27 Among them, MFC with porous electrodes in a flow-through configuration is outstanding owing to its remarkably high power density. 28 Compared with the flow-over type MFC where the catalysts are deposited on a two-dimensional (2D) support, the flowthrough type MFC using porous electrodes can bring enhanced mass transport due to the high specific surface area.…”

A membraneless microfluidic fuel cell with continuous multistream flow through cotton threads

“…Owing to advantages of simple structure, low cost, and eliminating membrane-related issues, MMFCs have received much attention and been considered as a promising miniature power source for portable devices. [1][2][3] Over the past decade, the performance of the MMFC has been improved from tens of μW cm −2 to hundreds of mW cm −2 by changing reactants, 4-7 modifying electrode structure, [8][9][10][11][12] or optimizing fuel cell design. [13][14][15][16][17] However, syringe pumps are needed to keep fuel and oxidant flow laminarly in parallel in most of microfluidic fuel cells, thus increasing the overall size of the system and limiting their miniaturization.…”

“…Two streams mix together only by the transverse diffusion. Owing to advantages of simple structure, low cost, and eliminating membrane‐related issues, MMFCs have received much attention and been considered as a promising miniature power source for portable devices . Over the past decade, the performance of the MMFC has been improved from tens of μW cm −2 to hundreds of mW cm −2 by changing reactants, modifying electrode structure, or optimizing fuel cell design .…”