Subject: [NEXTEL-1] Fuel cell breakthrough leading to longer battery life on phones

From: [email-masked]
Date: Sat, 13 Sep 2003 03:53:43 -0400

Fuel cell breakthrough leading to longer battery life on phones

The need to regularly recharge batteries in mobile phones, laptops and other
portable terminals may be eliminated in the future, according to the latest
developments by leading silicon chip manufacturer STMicroelectronics. ST, which
has long been one of the major suppliers of the silicon chips used in mobile
phones, has reported progress by one of its advanced R&D teams in developing tiny
fuel cells, small enough to fit inside a mobile handset, that could generate all
the electrical energy needed to power the phone from cheap and easily available
organic fuels.

A fuel cell is a device that generates energy using electrochemical reactions
instead of fuel combustion. In recent years, there has been enormous interest in
fuel cells because they promise to deliver cheap, clean energy. Although much of
the work in the emerging field of fuel cell technology has been aimed at
automotive applications, ST researchers have also been investigating the
replacement of the rechargeable batteries used in mobile phones by tiny fuel cells
that can be refilled with fuel whenever needed, just like refillable cigarette
lighters.

"Using fuel cells instead of batteries would make mobile phones lighter and much
more convenient to use as they could be simply topped up with fuel whenever
necessary. In addition, there would be significant environmental benefits as the
fuel can be derived from sustainable organic sources, while the by-products are
mainly water and a much lower level of carbon dioxide than is produced by burning
fossil fuels," says Dr. Salvo Coffa, who leads the Corporate Technology R&D team
that is researching the micro fuel cell technology.

The operation of a fuel cell involves the chemical interaction between hydrogen
and oxygen to produce water, heat and electrical energy. Typically, a fuel cell
consists of a pair of electrodes (the 'anode' and the 'cathode') separated by a
membrane that allows protons (hydrogen ions) to pass through the membrane but does
not allow an electric current to pass. In addition, catalysts such as platinum are
used to increase the rate of the reaction and therefore the amount of electrical
energy produced.
The main problem with applying fuel cell concepts to mobile phones is that the
power source (battery or fuel cell) must be able to deliver around 300mA of
current at 3.6V and it must not occupy a volume of more than around 12 cubic
centimeters. However, the output current of a fuel cell is directly related to the
common surface area between the electrodes and the membrane and to obtain 300mA of
current using conventional fuel cell technologies would require a surface area of
around 60 square centimeters, much larger than is available in a mobile phone.

ST has made important progress in overcoming this problem by developing new
technologies in which the fuel cell could be implemented as a 3D structure
containing thousands of buried microchannels that maximize the contact area
between the gases, the catalysts and the electrodes.

The ST research team has also succeeded in fabricating a special nanoporous layer,
consisting of a layer of silicon containing millions of pores, each measuring just
a few nanometers in diameter. The small pore sizes give the layer a very large
effective surface area, thus increasing the efficiency of the catalysis. In
addition, the ST team is working with the University of Naples to develop novel
membranes that exhibit high proton conductivity and lower cost compared to the
membrane materials that are commercially available today.

"ST is committed to researching new technologies that could help to minimize the
impact of industrial and consumer products on the global environment. Although
there is still further work to do before these developments can be integrated into
a commercial technology, we are very excited about their potential," says Coffa.
The ST work on micro fuel cells is partially supported by a National Research
Project, aimed at developing small fuel cells for portable electronic
applications, in which several other Italian institutions participate (CNR-IMM,
CNR-ITAE, CNR-ITS and Pirelli labs). In the project, ST leads and coordinates the
activity related to micro-fuel cell fabrication and integration.

Posted to the site on 12-Sep-03

http://www.cellular-news.com/story/9705.shtml

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