Portable Direct Methanol Fuel Cell

The energy capacity of the current Li-ion batteries is around 130 Wh/kg. We estimate about 1,300 Wh/kg or more for a well-designed portable direct methanol fuel cell based on carbon nanotube technology."... 

Narayanan SR, Valdez TI (2003) Portable direct methanol fuel cell systems. In Vielstich W, Lamm A, Gasteiger H (eds) Handbook of fuel cells fundamentals, technology and applications, vol 4. Wiley, Chichester, England, Part 1, pp 1133-1141... 

Barton S.C., Murach B.L., Fuller T.F., and West A.C. (1998) A methanol sensor for portable direct methanol fuel cells , Journal of the Electrochemical Society, 145, 3783-3788. 

Girishkumar, G., Hall, T.D., Vinodgopal, K., and Kamat, P.V. (2006) Single wall carbon nanotube supports for portable direct methanol fuel cells. Journal of Physical Chemistry B, 110 (1), 107-114. 

The preparation complexity of perfluorosulfonated membrane and the high cost have restricted PEMFC from commercialization. Many researchers are dedicated to the development of nonflnorinated PEM. The American company Dais has developed styrene/ethylene-bntylene/styrene triblock polymer [51]. This membrane is especially snitable for small power PEMFC working at room temperature. The lifetime of the membrane is up to 4000 h. Baglio did some experiments to test the performance comparison of portable direct methanol fuel cell mini-stacks between a low-cost nonfluorinated polymer electrolyte and Nafion membrane. He found that at room temperature, a single-cell nonfluorinated membrane can achieve maximum power density of about 18 mW/cm. As a comparison, the value was 31 mW/cm for Nafion 117 membrane. Despite the lower performance, the nonfluorinated membrane showed good characteristics for application in portable DMFCs especially regarded to the perspectives of significant cost reduction [52]. 

Baglio, V., Stassi, A., Modica, E., Antonucci, V., Arico, A.S., Caracino, R, BaUabio, O., Colombo, M., and Kopnin, E. Performance comparison of portable direct methanol fuel cell mini-stacks based on a low-cost fluoiine-free polymer electrolyte and Nafion membrane. Electrochimica Acta, 55(20), 6022-6027, 2010. 

Polyfuel (USA), a spin-off of SRI International, is developing direct methanol fuel cells to replace Lithium ion batteries in wireless, handheld and portable devices, based on patented, proprietary technology. PolyFuel s membranes are based on hydrocarbon polymers, rather than perfluorinated and are considered to be best-in-class for portable direct methanol fuel cells (DMFC) designed for portable electronic devices such as laptops, PDAs or cell phones. 

The dynamic behavior of fuel cells is of importance to insure the stable operation of the fuel cells under various operating conditions. Among a few different fuel cell types, the direct methanol fuel cell (DMFC) has been known to have advantages especially for portable... 

The electrocatalytic oxidation of methanol has been widely investigated for exploitation in the so-called direct methanol fuel cell (DMFC). The most likely type of DMFC to be commercialized in the near future seems to be the polymer electrolyte membrane DMFC using proton exchange membrane, a special form of low-temperature fuel cell based on PEM technology. In this cell, methanol (a liquid fuel available at low cost, easily handled, stored, and transported) is dissolved in an acid electrolyte and burned directly by air to carbon dioxide. The prominence of the DMFCs with respect to safety, simple device fabrication, and low cost has rendered them promising candidates for applications ranging from portable power sources to secondary cells for prospective electric vehicles. Notwithstanding, DMFCs were... 

In addition to these smaller applications, fuel cells can be used in portable generators, such as those used to provide electricity for portable equipment. Thousands of portable fuel cell systems have been developed and operated worldwide, ranging from 1 watt to 1.5 kilowatts in power. The two primary technologies for portable applications are polymer electrolyte membrane (PEM) and direct methanol fuel cell (DMFC) designs. 

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... 

Therefore, methanol is the top candidate because of its low price, less toxicity, high energy density and easy handling. Although direct methanol fuel cells may need an auxiliary system to treat unoxidized or partially oxidized fuel in the exhaust gas, direct methanol fuel cells are still a very attractive system as a portable power source. 

Fuel cells are electrochemical devices that convert the chemical energy of the fuels directly into electrical energy, and are considered to be the key technology for power generation in stationary, automotive, portable and even microscale systems. Among all kinds of fuel cells, direct methanol fuel cells have really exhibited the potential to replace current portable power sources and micropower sources in the market (Yao et al., 2006). 

Performance of Direct Methanol Fuel Cells for Portable Power Applications... 

Direct methanol fuel cell technology is relatively new compared to that of fuel cells powered by pure hydrogen, and research and development are roughly 34 years behind that of other fuel cell types. Nonetheless, the DMFC appears to be the most promising as a battery replacement for portable applications such cellular phones and laptop computers, and a number of manufacturers are already introducing commercial versions of these applications. 

Shipments of fuel cell-equipped mobile devices could grow very rapidly if they can eliminate the need for frequent recharging of current battery-powered models. The Medis 24/7 Power Pack in April 2007. It is a portable, disposable power source for small electronic devices such as cell phones and MP3 players. Manufactured by Medis Technologies, it is based on Direct Liquid Fuel cell technology, and may be of particular utility in military applications. Elsewhere, MTI MicroFuel Cells manufactures a power pack for portable electronics that is based on direct methanol fuel cell technology that it calls Mobion. 

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