On-chip direct methanol fuel cells of a monolithic design: consideration on validity of active-type system

Tominaka, Satoshi; Obata, Hiroyuki; Osaka, Tetsuya

doi:10.1039/b904339j

Cited by 15 publications

(10 citation statements)

References 28 publications

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“…With the electrodes within the same layer as the microfluidic channels and manifolds, this strategy leads to low profile cells which can be easily integrated into 'onchip' applications such as sensors, a feature which distinguishes them from conventional MEA based cells [118]. This has made this fabrication style particularly favoured by research groups investigating biofuels such as glucose for potential biological or point of care medical applications [82], [83], [85], [111], [113], [116], [119], [120].…”

Section: Research Perspectivesmentioning

confidence: 99%

“…As open cells depend on reactant flow, any commercial application involving CLFCs will inevitably require balance of plant items such as pumps and reactant storage. Even if future cells can eliminate such ancillary parts by relying on gravity induced flow, capillary action [118], [154], or even gaseous venting [155], [156]; the question of scale remains a significant barrier to commercialization as power sources. Since these cells are inherently limited in size by the co-laminar concept of reactant separation, it is crucial for these cells to be as effective as possible to achieve practical power outputs.…”

Section: Motivation and Objectivementioning

confidence: 99%

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Co-laminar flow cells for electrochemical energy conversion

Goulet

Kjeang

2014

Journal of Power Sources

104

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A recently developed class of electrochemical cell based on co-laminar flow of reactants through porous electrodes is investigated. New architectures are designed and assessed for fuel recirculation and rechargeable battery operation.Extensive characterization of cells is performed to determine most sources of voltage loss during operation. To this end, a specialized flow cell technique is developed to mitigate mass transport limitations and measure kinetic rates of reaction on flow-through porous electrodes. This technique is used in in conjunction with cyclic voltammetry and electrochemical impedance spectroscopy to evaluate different treatments for enhancing the rates of vanadium redox reactions on carbon paper electrodes. It is determined that surface area enhancements are the most effective way for increasing redox reaction rates and thus a novel in situ flowing deposition method is conceived to achieve this objective at minimal cost. It is demonstrated that flowing deposition of carbon nanotubes can increase the electrochemical surface area of carbon paper by over an order of magnitude. It is also demonstrated that flowing deposition can be achieved dynamically during cell operation, leading to considerably improved kinetics and mass transport properties. To take full advantage of this deposition method, the total ohmic resistance of the cell is considerably reduced through design optimization with reduced channel width, integration of current collectors and reduction of reactant concentration. With electrodes enhanced by dynamic flowing deposition the cell presented in this study demonstrates nearly a fourfold improvement in power density over the baseline design.Producing more than twice the power density of the leading co-laminar flow cell without the use of catalysts or elevated temperatures and pressures, this cell provides a lowcost standard for further research into system scale-up and implementation of co-laminar flow cell technology. More generally, the experimental technique and deposition method developed in this work are expected to find broader use in other fields of electrochemical energy conversion. am also very grateful to my graduate colleagues at SFU and friends in FCRel, with a special mention to Omar in particular, for all the pleasant conversations and good times.I wish there had been more.Last but not least, I'd like to acknowledge all the family and friends I was unable to spend quality time with due to this work. I look forward to seeing you all again.vi Tables Table 1. for their higher specific energy and energy density [6]. For the same reasons, the lower power (< 100 W) market which is driven by portable consumer electronics, is currently 2 dominated by closed cell lithium ion batteries in particular [7]. As these batteries reach their limits and fail to keep up with the energy requirements of modern electronics, micro fuel cells with passively pumped higher energy density liquid reactants such as methanol have been suggested as a potential replacement [8].Regardless...

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Section: Research Perspectivesmentioning

confidence: 99%

Section: Motivation and Objectivementioning

confidence: 99%

Co-laminar flow cells for electrochemical energy conversion

Goulet

Kjeang

2014

Journal of Power Sources

104

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“…The rapid development of miniature devices (e.g., microsensors)1 has resulted in an increasing demand for miniature power sources. For example, microfuel cells,2–7 microbatteries,8 and microsolar cells9 have been considered as possible on‐chip power sources. This paper proposes a novel design for a microfuel cell as an on‐chip power source and demonstrates its fabrication and operation to prove the concept.…”

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confidence: 99%

A Thin‐Film Direct Hydrogen Peroxide/Borohydride Micro Fuel Cell

Wang¹,

Guo²,

Xia³

2013

Advanced Energy Materials

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The rapid development of miniature devices (e.g., microsensors) [ 1 ] has resulted in an increasing demand for miniature power sources. For example, microfuel cells, [2][3][4][5][6][7] microbatteries, [ 8 ] and microsolar cells [ 9 ] have been considered as possible on-chip power sources. This paper proposes a novel design for a microfuel cell as an on-chip power source and demonstrates its fabrication and operation to prove the concept. The design of the on-chip cell concurrently realizes a high operating voltage of 1.6 V, and high power. Its simple design is important from the viewpoints of fabrication (e.g., replication), integration, and compatibility with other microdevices.Fuel cells that directly convert chemical energy into electricity with high effi ciency attract considerable research attention. [10][11][12][13][14] All such fuel cells involve the couplings of cathode/ anode, reduction/oxidation reactions, charge movement (electron-transfer/ion-transfer), and often reactions in either acid or alkaline electrolyte. During operation, cathodic fuel is reduced (i.e., gains electrons) and anodic fuel is oxidized (i.e., looses electrons) simultaneously. The potential difference between the cathode and anode results in the generation of current where electrons move from anode to cathode in the external circuit and ions move in the electrolyte. Depending on the acid (C H + )/ alkaline(C OH-) concentration in the electrolyte, fuel cells can be described as being either acidic (C H + > C OH-≈ 0) or alkaline (C OH-> C H + ≈ 0). Because the stable potential window of water (H 2 O) is only about 1.23 V at various pH values, the measured cell voltage of these developed fuel cells is around 1 V which is lower than 1.23V.Direct borohydride fuel cells (DBFCs) have attracted increasing attention since their demonstration by Amendola et al. in 1999, [ 15 ] and more recently considerable efforts have been made to further improve their performance. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In principle, DBFCs can only work in an alkaline electrolyte because borohydride is unstable in neutral and acidic media. [ 18 , 20 ] Accordingly, conventional DBFCs use a single alkaline electrolyte for both the anode and the cathode. Although the theoretical cell voltage of conventional DBFCs (with a single alkaline electrolyte for both the anode and the cathode) is 1.64 V, the measured cell voltage at open-circuit conditions of these cells is only around 1 V, which is also because the stable potential window of water is only 1.23 V. However, the reduction potential of cathodic fuel (e.g. O 2 , H 2 O 2 , etc.) is much lower in alkaline medium when compared with that in acidic medium. If the reduction of cathodic fuel (O 2 or H 2 O 2 ) in an acid electrolyte can be coupled with oxidization of anodic fuel (BH 4 − ) in an alkaline electrolyte, the DBFC would exhibit much higher operating voltage. This should be an interesting topic and a great challenge because one fuel cell can not contain both acidelectrolyte and a...

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“…Recent progress in microelectrochemical devices, for example, on-chip fuel cells [1][2][3][4][5][6], microbatteries [7,8], and onchip sensors [9,10], inevitably requires developments of both electrode materials with a large surface area and processes for depositing such materials precisely onto the tiny current collectors. For such selective deposition, we regard that electrodeposition is attractive, because this technique enables us to selectively synthesize metals onto conductive materials, even onto microelectrodes and to directly synthesize alloys without thermal treatment [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Nanoporous PdCo Catalyst for Microfuel Cells: Electrodeposition and Dealloying

Tominaka

Osaka

2011

Advances in Physical Chemistry

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PdCo alloy is a promising catalyst for oxygen reduction reaction of direct methanol fuel cells because of its high activity and the tolerance to methanol. We have applied this catalyst in order to realize on-chip fuel cell which is a membraneless design. The novel design made the fuel cells to be flexible and integratable with other microdevices. Here, we summarize our recent research on the synthesis of nanostructured PdCo catalyst by electrochemical methods, which enable us to deposit the alloy onto microelectrodes of the on-chip fuel cells. First, the electrodeposition of PdCo is discussed in detail, and then, dealloying for introducing nanopores into the electrodeposits is described. Finally, electrochemical response and activities are fully discussed.

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On-chip direct methanol fuel cells of a monolithic design: consideration on validity of active-type system

Cited by 15 publications

References 28 publications

Co-laminar flow cells for electrochemical energy conversion

Co-laminar flow cells for electrochemical energy conversion

A Thin‐Film Direct Hydrogen Peroxide/Borohydride Micro Fuel Cell

Nanoporous PdCo Catalyst for Microfuel Cells: Electrodeposition and Dealloying

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