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The world's smallest working fuel cell has been created by US chemical engineers, at just 3 millimetres across. Future versions of the tiny hydrogen-fuelled power pack could replace batteries in portable gadgets.
While batteries are used to do that today, fuel cells are able to store more energy in the same space. Even the most advanced batteries have an energy density an order of magnitude smaller than that of a hydrogen fuel tank.
Yet batteries are much easier to make at the small scale than the pumps and control electronics of a fuel cell. And small pumps can use more energy than they generate. Chemical engineers working at the University of Illinois at Urbana-Champaign have developed a hydrogen fuel cell that measures only 3 millimeters across. That could mean longer lasting, eco-friendly power for your gadgets. This new cell utilizes only four components—a water reservoir and a chamber containing metal hydride separated by a thin membrane with an assembly of electrodes that conduct electricity underneath. Because of the small size of the cell, the team was able to eliminate the pump, pressure sensor, and controlling electronics that create such a power drain in typical fuel cells. The first designs of the cell were capable of generating 0.7 volts and a current of 0.1 milliamps for 30 hours—but they claim that new versions can deliver 1 milliamp at a similar voltage.
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