Power plays..the next generation of batteries..

[KiwiCoromandel]

TOXIC, lumpen and sometimes downright dangerous, batteries are the fly in the ointment of portable electronics.

While Dell, Apple and now Toshiba have recalled nearly 6 million of them, laboratories in Israel, Japan and the US are striving to be the first with commercial versions of the next generation of batteries - printable, paper-thin derivatives to power the micro devices that are poised to out-evolve our gizmos while keeping our environment green.

Film-thin printed batteries have been commercially viable since 2001 when Israeli company Power Paper (www.powerpaper.com) unveiled a caseless battery just 0.5 mm thick that could be printed on paper and even plastic using the same silkscreen process that commercial printers use. The two ends of the battery - the cathode and anode - are printed along with an electrolyte ink on to a flat surface, enabling the mass-production of flat batteries to the size, thickness and form required for the design of any product. Separated by electrolyte ink, zinc anodes and magnesium dioxide cathodes form the top and tail of Power Paper's tiniest battery. Just 0.6 mm thick and 39 mm across, it can generate 1.5 volts and a mere fraction of an amp - small, but enough to power electrically charged cosmetic patches for the skin, talking greeting cards and tags. And they're cheap too, at about $1.25 each. Stack them together and you have a more potent power pack, say its makers.

Low-power applications have been limited, says Barry Huret. of Huret Associates, a battery consulting company in the US. "For the moment, such paper-thin batteries are going to be limited to the likes of RFID tags and smart cards because the energy they produce is not that significant," he says.

But other power-frugal products, such as implantable medical devices, remote sensors and miniature transmitters powered by film-like batteries are on their way to commercialisation already.

"RFID tags with a proper power source will be able to transmit more and easier-to-read information about the object it's embedded in. Paper too will take on a new life in packaging. Even cardboard boxes on shelves could double in shops as small ads for their contents," Mr Huret says.

Japanese printing corporation Toppan recently piloted at a Tokyo train station a series of A4 posters made of electronic paper powered by an ultra-thin battery embedded invisibly within it. Passers-by were treated to updated weather reports, news and ads.

E-paper is low on power demand and can display text for months on the charge from a conventional AA battery, so Toppan's trial hardly tested the endurance of thin batteries. The challenge is to adapt the technology to power digital audio players, mobile phones and other portable devices, making them smaller, lighter - and perhaps even wearable - with longer periods between recharges.

"If electronics become more sophisticated so they use less energy, they can be powered by something very small, one tiny lithium battery for example, or even a series of thin batteries laid one on top of another," Mr Huret says.

Meanwhile conventional battery developers are arguing about the best materials for printable batteries. Most are experimenting with combinations of metals found in today's regular batteries (low-cost zinc/manganese dioxide) and rechargeable batteries, which use the more expensive lithium for longer life and increased power capacity.

Japanese electronics giant NEC is betting on polymers for micro-thin batteries as they are bendable, non-toxic, cheap and rechargeable. NEC is developing a battery that claims a charging time of less than 30 seconds. Made from a plastic "organic radical polymer", at 300 microns it is the width of a human hair and does not contain any harmful heavy metals.

Battling against such electronic giants is inventor Nobuyhuki Tabata, who claims to have discovered his own battery technology after studying rock samples for 20 years. Mr Tabata refuses to say what minerals he uses in his printable, 0.2 mm-thick batteries, but claims his inventions produce almost 10 times the energy density of rivals with the same volume.

He does let on that he uses a solid natural mineral electrolyte printed between the cell's graphite and aluminium plate electrodes. When used in series, his batteries can produce 30 volts - enough to supply a small monitor and data transmitter. A credit card-sized array of his cells would power a mobile phone, use lithium for the cathode and will be rechargeable, he says.

Tabata set up Ion Technology four years ago and says leading electronic companies are investing in or trying to emulate his technology. By next year he plans to have batteries in production that will power smart cards used in Japan.

source:GUARDIAN

image:mdtmag.com....THE next generation of BATTERIES...