Integrated micro-power source based on a micro-silicon fuel cell and a micro electromechanical system hydrogen generator

Zhu, Likun; Lin, Kevin Y.; Morgan, Robert D.; Swaminathan, Vikhram V.; Kim, H.S.; Gurau, Bogdan; Kim, D.; Bae, Byungchan; Masel, Richard I.; Shannon, Mark A.

doi:10.1016/j.jpowsour.2008.09.028

Cited by 25 publications

(19 citation statements)

References 39 publications

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“…Many researchers have focused on minimization of DMFC [2][3][4]. In this case it is required to fabricate a micro DMFC array on a plane surface by dividing a PFSA film into micro pieces.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Stress Effect on Ionic Conductivity of Perflurosulfonic Acid (PFSA) Film by Photolithography

Sakurai

Kawai

2012

J. Photopol. Sci. Technol.

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Direct Methanol Fuel Cell (DMFC) consists of a perflurosulfonic acid (PFSA) electrolyte is attractive as a portable power source. It is possible to fabricate a DMFC array by dividing a PFSA film into micro pieces by photolithography. In this regard, it is known that photoresist film causes significant compressive and tensile stress generation in an underlying layer. Then it is needed to control preparation condition of photoresist film formed on a PFSA film. The effect of compressive load in a PFSA film is observed as enhancement of electro motive force. By applying compressive load to a PFSA film, proton ionic conductivity would be enhanced. On the other hand, a tensile load acts to decrease electro motive force. Therefore photoresist pattern shape should be designd effectively in order to enhance proton ionic conductivity of PFSA film.

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“…Many researchers have focused on minimization of DMFC [2][3][4]. In this case it is required to fabricate a micro DMFC array on a plane surface by dividing a PFSA film into micro pieces.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Stress Effect on Ionic Conductivity of Perflurosulfonic Acid (PFSA) Film by Photolithography

Sakurai

Kawai

2012

J. Photopol. Sci. Technol.

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“…Unfortunately, many of them are impractical for lH 2 -PEMFC applications due to the low energy density, complex control units, relatively high cost, and the often demanding storage conditions (e.g., high pressure, low temperature) (Zhu et al 2009b). Recently, onboard hydrogen storage and generation via the hydrolysis reactions of metal and chemical hydrides has attracted a lot of attention for hydrogen proton exchange membrane fuel cell applications (Gervasio et al 2005;Yang et al 2010;Zhu et al 2008bZhu et al , 2009b. Among these methods, hydrogen generation using a catalytic hydrolysis reaction of an alkaline sodium borohydride (NaBH 4 ; denoted as SB) solution has been widely explored due to its high energy density, safety, and ease of control (Kojima et al 2002(Kojima et al , 2004Oronzio et al 2009;Pinto et al 2006;Pozio et al 2008;Richardson et al 2005;Xia and Chan 2005;Zhang et al 2006Zhang et al , 2007 The alkaline SB solution is safe and stable at room temperature because the hydrolysis reaction can be greatly inhibited or controlled by the addition of NaOH to the solution (increasing pH) (Pozio et al 2008).…”

Section: Introductionmentioning

confidence: 99%

An on-demand microfluidic hydrogen generator with self-regulated gas generation and self-circulated reactant exchange with a rechargeable reservoir

Zhu

Kroodsma

Yeom

et al. 2011

Microfluid Nanofluid

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This article introduces an on-demand microfluidic hydrogen generator that can be integrated with a microproton exchange membrane (PEM) fuel cell. The catalytic reaction, reactant circulation, gas/liquid separation, and autonomous control functionalities are all integrated into a single microfluidic device. It generates hydrated hydrogen gas from an aqueous ammonia borane solution which is circulated and exchanged between the microfluidic reactor and a rechargeable fuel reservoir without any parasitic power consumption. Ammonia borane is chosen instead of sodium borohydride because of its faster hydrogen generation rate, higher hydrogen storage capability, stability, and better catalyst durability. The self-circulation of the ammonia borane solution was achieved using directional growth and selective venting of hydrogen bubbles in micro-channels, which leads to agitation and addition of fresh solution without consumption of electrical power. The self-regulation mechanism ensures that hydrogen can be supplied to a fuel cell according to the exact demand of the current output of the fuel cell. The circulation flow rate of ammonia borane solution is also automatically regulated by the venting rate of hydrogen at the gas outlet. Design, fabrication, and testing results of a prototype system are described. The hydrogen generator is capable of generating hydrogen gas at a maximum rate of 0.6 ml/min (2.1 ml/min cm 2 ) and circulating aqueous ammonia borane at a maximum flow rate of *15.7 ll/min. The device has also been connected with a micro-PEM fuel cell to demonstrate the feasibility of its practical applications in a high-impedance system.

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“…From the system perspective, the thrust is to simplify these auxiliaries and design them to deliver fuel and control the device, with minimal power consumption, so that we can increase on-board fuel storage to maximize energy density. We have previously reported efforts on miniaturization and integration to limited energy/power densities and some control (Zhu et al 2008b(Zhu et al , 2011Moghaddam et al 2008aMoghaddam et al , b, 2010Swaminathan et al 2009). In this paper, we miniaturize a proton exchange membrane (PEM) fuel cell and integrate with it an on-board hydrogen generator and MEMS control mechanisms that exploit surface phenomena at these scales to accomplish efficient transport and control.…”

Section: Introductionmentioning

confidence: 99%

Integrated micro fuel cell with on-demand hydrogen production and passive control MEMS

Swaminathan

Zhu

Gurau

et al. 2011

Microfluid Nanofluid

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An ever increasing demand for packaging more energy on-board to meet the needs of power hungry microsystems is driving the miniaturization of power generators. We report a fully integrated Power MEMS, in the 10-lL size, designed to deliver high energy and power densities. On-board hydrogen production and an efficient control scheme that facilitates integration with a fuel cell membrane electrode assembly are key elements for micro energy conversion. A millimeter-scale reactor produces hydrogen by hydrolysis of CaH 2 and LiAlH 4 , to yield energy densities of the order of 200 Whr/L. A passive microfluidic control scheme, incorporating surface tension to pump water in a microchannel for hydrolysis and microvalve control using hydrogen backpressure, facilitates delivery and regulation and eliminates bulky auxiliaries that consume parasitic power. We tested the ability of this control scheme to improve uniformity of power delivery during long periods of lower demand, with fast switching to mass transport regime on the order of seconds, and realized peak power density of up to 391.85 W/L. Prototypes have been tested for duty periods from 2-48 h, with multiple switching of power demand in order to establish performance across multiple regimes. Critical to the realization of the integrated power MEMS, and its energy and power density, are effects of water transport and byproduct hydrate swelling on hydrogen production in the microreactor. While CaH 2 showed superior hydrogen release kinetics that enhances power density, LiAlH 4 provided greater energy density due to reduced byproduct expansion that permitted increased hydrogen production.

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Integrated micro-power source based on a micro-silicon fuel cell and a micro electromechanical system hydrogen generator

Cited by 25 publications

References 39 publications

Mechanical Stress Effect on Ionic Conductivity of Perflurosulfonic Acid (PFSA) Film by Photolithography

Mechanical Stress Effect on Ionic Conductivity of Perflurosulfonic Acid (PFSA) Film by Photolithography

An on-demand microfluidic hydrogen generator with self-regulated gas generation and self-circulated reactant exchange with a rechargeable reservoir

Integrated micro fuel cell with on-demand hydrogen production and passive control MEMS

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