Transcript
As explained in our sister-publication, Trends, battery-powered drones and similar electric aircraft are too limited for many applications they could otherwise perform; the weight-constrained battery capacity limits flight time to well under an hour. That's why military drones use costly turbine engines.
The only clean, safe, low-cost answer seems to be fuel cells. And now, a fuel cell developed by a Korean research team at POSTECH is ready to solve this problem. The miniaturized solid oxide fuel cell (micro-SOFC) can also replace lithium-ion batteries in smartphones, laptops, and other small electronic devices.
Best of all the SOFC can be utilized, not only for small-scale applications, but also for a large-capacity fuel cells that can be used for electric vehicles. This means lithium-ion and similar battery technology may be obsolete by the time the vaunted "giga-factories" are online.
The research was published in the March 2016 edition of the journal, Nature Scientific Reports. The SOFC, is a so-called third-generation fuel cell technology. It has been intensively studied because of its simple structure and lack of problems with corrosion or loss of electrolyte. Previously, silicon has been used after lithography and etching as a supporting component of small oxide fuel cells. This technology, however, has exhibited rapid degradation or poor durability due to the thermal-expansion mismatch with the electrolyte; thus, it cannot be used in actual devices that require fast on/off operation.
To resolve the problem, the Korean team developed the world's first fuel cell incorporating a totally new technology. That technology combines porous stainless steel, which is thermally and mechanically strong as well as highly stable to oxidation/reduction reactions, with thin-film electrolyte and electrodes with minimal heat capacity. As a result, performance and durability were increased simultaneously.
To ensure that large scale SOFC manufacturing would be commercially viable, the fuel cells are made by a combination of tapecasting-lamination-cofiring (TLC) techniques. The fuel cells exhibited a high power density of 560 mW per square-cm at 550 degrees C.
The research team expects this fuel cell may be suitable for portable electronic devices such as and drones that require high power-density and quick on/off. They also expect to develop large and inexpensive fuel cells for a power source of next-generation automobiles.
In test with the SOFC fuel cell, drones were able fly for more than one hour. The team expects SOFC-enabled smartphones that can be charged once a week or less.
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