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THE next generation of smaller, faster laptops could be built with tiny
supercapacitors made possible by a new chemical technique.

Capacitors store electric charge; the bigger their surface area the more
charge they can hold. So it鈥檚 a struggle to make capacitors that are small
enough for tomorrow鈥檚 ever-shrinking devices, yet store useful amounts of
charge.

One idea is to coat electrodes with nanocrystals of metal oxides. But as the
crystals are heated during manufacture they grow too large to be of any use.

Now Nae-Lih Wu of the National Taiwan University in Taipei has found a way to
seal crystals of tin oxide laced with antimony and stop them growing. Hydroxyl
groups on the crystals鈥� surfaces allow them to grow or even stick together. But
the team was able to block these active sites using a chemical called
hexamethyldisilazane, which converts the hydroxyl groups to methyl siloxyl
groups.

Using this technique, Wu was able to keep tin and other metal oxide crystals
down to 10 nanometres or less鈥攔oughly the size of 100 hydrogen atoms side
by side. Untreated antimony-laced tin oxide crystals were 100 times as large,
and could store only half as much electrical energy per gram.

鈥淥ne of the problems of the entire nanoworld is getting materials to retain
their nanostructure while you process them,鈥� says Bertram Diemer, a chemical
engineer at DuPont Engineering Technology in Delaware. 鈥淭his is the just the
type of advance that we need for nanotechnology to reach its full potential.鈥�