Sony Prototypes Ultra-Small Fuel Cell

Sony has prototyped an ultra-small fuel cell system that fits into the palm of your hand. Including fuel cell, fuel cartridge, Li-polymer rechargeable battery and control circuit, it measures about 50 x 30 x 20mm. This is the first announcement by the company that it has prototyped a practical fuel cell system including rechargeable battery, control circuit and other elements.

Until now, Sony has limited its involvement with portable fuel cells to announcing evaluation results for solid polymer electrolyte membranes using fullerene, membrane electrode assemblies (MEA) using them, and similar projects. The new announcement is positioned as a product prototype. According to an engineer at Sony's Material Laboratory, "We have been aiming for a system that can be put into mobile gear, and we've finally reached the level of commercial design."

The prototype is a direct methanol fuel cell, using methanol fuel, and has an active design with a pump to regulate fuel supply. Output density has not been disclosed, but instantaneous peak output is 3W. A Sony spokesman explained: "3W is more than sufficient to handle peak output demand for a mobile phone."

Energy utilization efficiency is also high: 10cc of methanol will power a one-segment mobile phone video receiver for 14 hours of continuous viewing. The company plans to work on commercial implementations for a variety of portable equipment.

As a hybrid combining fuel cells with Li-polymer rechargeable batteries, the new design can absorb abrupt load fluctuations fairly easily. When high current is needed, such as for mobile phone transmission, the rechargeable battery kicks in. The fuel cell maintains a constant output, so that it can output at the current and voltage optimizing fuel cell utilization efficiency, said a Sony source.

Extra electricity generated by the fuel cell is used to charge the rechargeable battery, further improving energy utilization efficiency. 1cc of methanol yields 1.1Wh of energy, or at least three times Sony's prior prototype. The current version of the prototype uses a 160mAh Li-polymer rechargeable battery.

A software algorithm was developed to regulate the speed of fuel supply to the fuel cell, implemented through the control circuit. An 8-bit general-purpose microcontroller would be adequate for the control circuit. Special channels in a finely detailed structure are used to supply the fuel, but details have not yet been released.

The solid polymer electrolyte membrane is the fullerene material Sony has announced in the past. The electrode catalyst appears to be a newly developed platinum alloy. Sony has filed for patents on system, materials and other aspects of the technology.

http://techon.nikkeibp.co.jp/article/HONSHI/20080625/153880/

Source: Tech-On