Superfast-charging batteries? Whoa there, MIT
New 'lectrode tech causes premature inkgasm
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. ®
COMMENTS
CPUs, hydrogen
"CPUs step down the voltage locally".
That's correct (ish), and without a transformer. Any worthwhile power supply these days (from phone chargers upwards) uses the miraculous technology of "switched mode power supplies", high efficiency, light weight, no transformer (maybe a small lightweight inductor with no metal or ferrite), marvellous stuff. Go read about it, this isn't the place for a lesson.
"Hydrogen"
Is not (just) a fossil fuel. In Iceland they make it from water and geothermal electricity. In Africa they could make it from water and solar electricity. As Europe (in particular the UK) is already buying liquefied natural gas from north Africa, we already have much of the technology to get liquid hydrogen from there too (they have no shortage of sunshine, and near the coast, water is freely available). Don't dismiss H2 so easily, you (or maybe your national electricity supply) may well need it one day.
Not sure about LNG or LH fuelled cars in tunnels though - but don't tell the Highways Agency.
@Rota
Beats me, which is saying little as I'm no expert. But PSUs put out 12, 5 and 3.3V, while cpus use around 1-1.5V (very approx), and I've seen references to transformers near the chipset.
It's an engineering problem
"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."
duh. You would likely only need to deliver about 10-20V DC. It is quite possible to make a charger that will do this at very high current, given that you have 240VAC at 13A available. Only heavy wiring would be charger output to the battery, which could be quite short - even 6 inches would do it. So voltage drop isn't such a problem as it might appear. Actually all you have to do is make sure the cable doesn't melt, the PSU can easily regulate away the voltage drop that occurs in the delivery wire by using a seperate sense wire back to the feedback network.
The problem is quite a bit tougher for the size of battery that a car would need. But in Europe, many houses do have 3-phase coming in, so supply is not such a problem. Of course, the overall load on the grid would increase significantly ...
I like the idea of switch in-out battery packs more, when you pull up at the filling station you just swap out a bunch of battery modules, pay, go. End of problem.
@MnM stepping down voltage at CPUs
CPUs step down the voltage locally? How do they do that when the the supply is DC?
Are you suggesting that CPUs have DC-DC converters using switch mode or linear devices such as transformers on the chip?
I don't need a 10 second charge
"This might be interesting to those interested in battery-electric power tools and such, although the "two batteries, one on charge one in use" seems to work well for them already."
I have a light weight drill without the normal giant battery hanging off the bottom. The problem is that I can drain a battery much faster then charge one. If I could charge the battery in 15-20 minutes I would not have the problem of running out of juice before the second battery has a reasonable charge.
