Direct methanol fuel cells miniaturization

Direct-methanol fuel cells (DMFCs) have attracted considerable attention for certain mobile and portable applications, because of their high specific energy density, low poison emissions, easy fuel handling, and miniaturization [129,130], However, the methanol permeation through electrolyte membranes (usually called methanol cross-over) in DMFCs still is one of the critical problems hindering the commercialization [131,132], Nafion , a... 

Fuel cells incorporating lithographic methods and masking/deposition/etching protocols have been fabricated on Si wafers and thereby satisfy two critical needs in a standard fuel cell collection of electrons (current collectors) and controlling the flow field of fuel and oxidant. Kelley et al. produced a miniature direct methanol fuel cell (DMFC) with a current— voltage and fuel utilization performance that matched standard-sized DMFCs prepared in-lab.A working volume for the miniature DMFC of 12 mm was reported, with an operational performance of 822 W h kg at 70 °C. ... 

The fuel cell has a proven history with solid oxide based systems. Recent needs for miniaturization have generated new ideas of fuel sources and structures. These include direct methanol fuel cells (DMFCs) and polymer electrolyte membrane fuel cells (PEMFCs). These fuel cells have advantages over others for several reasons. A key quality is the potential energy that the fuel sources provide with respect to the fuel costs. 

PEM fuel cells operate with hydrogen. At the moment, there is no hydrogen storage available which is suitable for miniature applications. For direct methanol fuel cells (DMFCs) a better storage opportunity exists in form of methanol cartridges. 

Roualdes S, Topala I, Mahdjoub H, Rouessac V, Sistat P, Durand J (2006) Sulfonated polystyrene-type plasma-polimerized membranes for miniature direct methanol fuel cells. J Power Sources 158 1270-1281... 

The second aim is the miniaturization of devices, oti which has focused the work of many research groups and companies. Thus, in 2004 Toshiba Inc. presented a direct methanol fuel cell with a size of 22 x 56 x 4.5 nun with a small tank of methanol (2 cm in volume and 8.5 g weight) incorporated, with an output power of 100 mW, which, according to the company is sufficient to maintain a mp3 device operating over 20 h [39]. 

An apt example for a sol-gel synthesis in very small quantities in a highly miniaturized system has been given by Reddington et al. [11], who have converted an ink-jet printer to be able to deliver precursors for oxide materials. These precursors were printed on graphite paper and the formed materials were evaluated with respect to their performance as anode catalysts in direct methanol fuel cells. 

Portable power—Many companies (MTI, Motorola, NEC, Fuji, Matsushita, Medis, Manhattan Scientific, Polyfuel) are developing miniature fuel cells as battery replacements for various consumer and military electronic devices. Because of fuel storage issues, most of them use methanol in either direct methanol fuel cells or through microreformer in regular PEM fuel cells. 

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