Superfast-charging batteries? Whoa there, MIT

http://www.theregister.co.uk/2009/03/12/fast_charge_battery_bubble_stab/
New 'lectrode tech causes premature inkgasm

By Lewis Page •

Posted in PCs & Chips, 12th March 2009 12:38 GMT

New battery technology developed at MIT has made a big media splash today, supposedly offering Li-ion energy storage which could charge up fully "in seconds". However, no such capability has been demonstrated: in fact the kit doesn't seem very important.

The ink storm results from the usual advance notices attendant on a letter written by Byoungwoo Kang and Gerbrand Ceder of MIT, describing their work on enhancing lithium iron phosphate electrodes. The letter is published in Nature this week, which should mean it is of some importance.

According to the Nature free publicity channel, Kang and Ceder have "have developed battery cells that can charge up in less time than it takes to read the first two sentences of this article". This line has been picked up by the mainstream media and some big guns online.

In outline, it appears that the two boffins have enhanced the properties of lithium iron phosphate cathodes with a thin coating of lithium-phosphate glass, helping the electrode achieve much more of it potential as a carrier of lithium ions. If more ions can move, more electricity flows. Charge and discharge rates should be much better - indeed, nine-second charge-ups are claimed.

With li-ion batteries normally taking some hours to fill up, this could be big stuff. The famous Tesla Roadster electric supercar runs on li-ion, for instance: and its biggest Achilles heel is the lengthy time required to get juiced up again after running the battery pack flat.

Fast-charging for phones or gadgets is mildly attractive, but only mildly. Normally it would be much cheaper to buy a spare battery and a battery charger as one already can in most cases - so allowing an instant swap once a device runs flat - than to get kit which could charge up your phone in nine seconds. (The power level involved would be similar to an oven: even if it somehow could be made to work without melting the phone, special domestic wiring would probably be required and the charger would be large and expensive.)

Still, fast-charging electric cars is big news, right?

Well, no actually - li-titanate batteries, offering electrocars which can top off in a few minutes, have been around for a while and such vehicles are nearing the market.

In any case, Ceder and Kang - while apparently happy to speak to journalists of fast-charging, unless that was made up by the scribes - don't yet claim fast charging for their kit among their scientific peers. They have only proven fast discharging, as one finds when looking at their actual letter (abstract here: subscription required for the whole thing). MIT Tech Review, one of the few publications to bother looking properly, merely says "the fast-discharging materials may also recharge quickly".

Fast discharge is mildly interesting: it could offer a rival to ultracapacitors in the field of rapid acceleration for hybrid cars, especially those recouping some of the kinetic energy lost during braking and then seeking to give it back fast in the form of decent acceleration. F1 racing cars will soon be doing this sort of thing, for instance.

All in all, though, this technology really doesn't seem to be worthy of the attention it's getting - particularly compared to other more mature kit like li-titanate.

One might say: who cares about a load of silly hacks and what they write?

Unfortunately, this kind of thing too often affects investment and development decisions: in other words, affects the movement of money. MIT claims that Kang and Ceder's kit has already been licensed by two companies. ®