Mini-Fuel Cells could replace batteries in portable devices

Monday September 29, 2003

Researchers at STMicroelectronics are developing fuel cells small enough to replace rechargeable batteries in mobile phones, laptops and other portable devices. Switching to fuel cells would enable mobile phones to be refilled with cheap and readily available organic fuel (like a refillable cigarette lighter) instead of recharging the batteries using increasingly scarce and expensive fossil fuel resources.

The development of the fuel cell as an alternative power source has to date been given impetus by the automotive industry, with the major hurdle for applying the technology to the portable electronics industry being the challenge of squeezing a fuel cell that will deliver enough power into a space of around 12 cubic centimetres.

Fuel Cells generate energy through an electrochemical reaction instead of fuel combustion - hydrogen and oxygen are converted onto water, heat and electrical energy. The problem in terms of the size/power relationship is that in a standard fuel cell design, which relies on using a pair of "flat" electrodes separated by an electrolyte membrane, the output current is directly related to the common surface area between the electrodes and the membrane. This means that to obtain the required 300mA of current using conventional fuel cell design, a surface area of around 60 square centimetres would be needed - not exactly pocket-sized.

To combat this problem, ST researchers are examining the possibility of a 3D fuel cell structure that could significantly boost the contact area using only a fraction of the volume.

"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.

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