Apple Exploring Innovative Lightweight Monopolar Fuel Cells, Patents Reveal
21 Oct 2011
Apple Inc., which briefly surpassed Exxon Mobil Corp. as the
world's most valuable company in August this year, is exploring
innovative fuel cell stack configurations for use in its highly
successful portable consumer electronics, two newly published
patent applications can reveal.
Published by the US Patent and Trademark Office (USPTO), the
applications are entitled Parallel Fuel Stack Architecture (US
2011/0256463) and Reduced-Weight Fuel Cell Plate (US
2011/0256465) and represent the company's desire to remove
some of the common caveats associated with fuel cell stack
development.
Fuel cells stacks are commonly built in series to boost voltage;
however this can mean the systems are subject to a single point of
failure and can suffer from potential anode nitrogen accumulation
and water flooding. Apple's products are famous for their
reliability and are so precisely engineered that stack surgery or
replacement could be problematic. Parallel Fuel Stack
Architecture aims to abate this by arranging multiple fuel
cells in a parallel configuration (shown right above) on a power
bus with a voltage-multiplying circuit. This would increase the
reliability of the stack and potentially allow it to power devices
of higher operating voltages than would be expected.
Bipolar
plates are typically constructed from conductive
corrosion-resistant materials such as stainless steel. These high
density materials add weight to the cell, and a stack of such cells
could prove too heavy for use in devices such as iPhones and iPods.
Reduced-Weight Fuel Cell Plate proposes the arrangement of
cells in a monopolar configuration (shown right below). Monopolar
plates are potentially thinner, lighter and cheaper than bipolar
plates and can allow cells to share adjacent electrodes, reducing
the total number of electrodes required in the stack. According to
the filing, even with the reductions in weight and cost the stack
could still contain the same number of cells as its bipolar
counterpart.
These latest applications follow a patent granted in
January for the use of metallic glass in the fabrication
of current collector plates such as bipolar, and indeed monopolar,
plates. This patent was widely linked with Apple's acquisition of
Liquidmetal - whose unique lightweight metal products have been
utilised thus far only in the iPhone SIM card removal tool.
Although having only just been made publicly available, the patents
were filed in April 2010. It is exciting to see Apple applying some
of its innovation to the enhancement of fuel cells and it gives
promise for the future direct integration of fuel cells into
portable consumer electronics.
Image: Flickr/Roger Schultz
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