Researchers at Cambridge University have proposed using nuclear magnetic resonance to work out why lithium batteries keep exploding. Lithium batteries are great - lots of battery life and relatively fast charge time: so it seems churlish to avoid using them just 'cos they blow up every now and then. But now researchers are …
Should be interesting if they manage to capture the full process including the explosion at the end. I wonder who gets to clean up the mess?
Hmm, good luck balancing that in the spinner*
without screwing up your very expensive supercooled superconducting box of tricks.
*NMR spectrometers are normally used to analyse chemical samples in solution, which are placed in a thin glass tube which sits in a magnetic 'spinner'. This is suspended in the middle of the spectrometer in a magnetic field, on a cushion of air. This then spins rapidly, hence the name 'spinner', in the middle of the superconducting magnet, whilst being blasted with pulses of radio frequency radiation. on eof the problems chemists have with this setup is that the spinners can become unbalanced if the tubes are not inserted correctly, resulting in the tube smashing against the inside of the spectrometer and covering it in your sample. This is generally considered to be a bad thing.
Did anyone mention spectroscopy?
I think they are planning to use NMR imaging (aka MRI). The sort of thing they use for creating images of internal organs and similar.
Right you are
You don't often hear it called NMR imaging these days, what with people being reluctant to be put inside a big machine with 'nuclear' in its name.
I attended a talk once from one of the guys who did early research into MRI scanners. The first ones he built were indeed cobbled together from redundant NMR spectrometers. This was some years ago, so unfortunately I can't remember more details...
Ed, modern scanners don't revolve the subject, they revolve the detector.
That's what the grinding noise is that comes out of the MRI scanner when you lie inside wondering if the damned thing is about to explode and whether some nitwit will enter the room with an oxygen cylinder and burst your head like a ripe melon before this interminable test is over and LET ME OUT OF THIS BLOODY MACHINE!
Because I once studied with one of the pioneers of NMR at UEA (home of Climategate), I was able to talk my way into the control room once my scan was over and I watched the pictures being built.
It was hands-down the neatest moment I've ever had out of that Chemistry degree.
Whooda thunk messing around with spinning tubes and plotters with the wrong pen so the bloody thing kept drilling holes in the paper while the never-ending set-up was being done using an orange (!) crt oscilloscope to set the phase and who forgot to jam the elevator doors and now we'll have to start again and the damned sample is spinning too fast now NO DON"T TURN THE MAGNET OFF AARRGGH would actually become the really neat and useful technology it has?
Now if only we can bring the price of using it down out of the ionosphere...
The person who cleans up the mess..
..is the next person who wants to use the NMR scanner.
That's how it works with the microwave in our office kitchen....
And what happens if you cook a Lithium battery in a microwave? You could help the project with some very useful research there...
As we have an NMR scanner I can tell you that the person who made the mess is responsible for cleaning it up, unless they are the mess, then things do get more complicated.
In the same way...
...The person who forgets to leave keys/wallet etc on the table at the entrance of the NMR room is in a lot of trouble when the entire assembly has to be drained and warmed to room temperature to retrieve said metallic items from the side of the magnet. They then have to explain to other users of the equipment why it is out of service for two days while beeing cooled back down to superconducting temperatures...
Your homework for the day is
Look up "Is It A Good Idea To Microwave This?" on Youtube. I believe that they have in fact microwaved a lithium ion battery. What it did, I cannot recall.
Out of all of their videos, the coolest one has to be where they microwaved the sodium vapor lamp. What a beautiful light show.
I recall when lithium batteries going pop first made the news and the media called upon lots of spurts to be suprised and claimed they hadn't seen it coming. Funny that, because I recall when people first started using lithium cells in RC aircraft (very useful in that environment - fast charge time and lots of charge for their weight) and there were quite a few explosions reported. This was way before exploding iPods made the news, so presumably these tech experts the media were quoting had a very limited field of expertise. Or perhaps they worked for the battery companies and admitting that they knew lithium cells had a habit of combusting could have been a bad marketing move.
Exploding cells in RC aircraft
I think the reason exploding iPods made it newsworthy is that you don't usually carry an RC plane in a pocket next to the family jewels.
"which is why NMR is now being proposed"
Whilst it is the correct term for it, but didn't we stop using it circa 1980 something? It scares the tabloid readers...
I think it's ...
mri only for medical use, otherwise in REAL science it's still nmr
<looks around> Creative Zen, eeePC, Psion 3a (rechargeables inside), mobile phone, little MP3 player (Li-on AAA), video camera, digital camera...
I wonder which will blow up first? I would hope for a scene from Terminator, get my money's worth, rather than a lame "ffft!", but it better not be the camera because, you know, pictures or it didn't happen!
like kate moss?
Kate moss is a subset of Si Moss, more known for exploding on aircraft and in niche adult entertainment.
Lithium dendrites that short the battery and cause it to explode?
Those dendrites must be tough little buggers not to simply melt with the current needed to heat the battery to bursting point.
@Stevie: I think that's the point... Pure Lithium is extremely flamable, it will even ignite on it's own when thrown in a bowl of water... so a bit of heat will definately do the job
It's the hydrogen generated when dropping it in water that's flammable, rather than the lithium itself.
I would guess the little spiney things that grow on metal connections.
My creation is alive!
(oh wait, we don't want that, do we?*)
*EI low tech, now some SOB in Darpa is going to try that. Right, so lose the whole thing to Skynet.
*loose the batteries of hell and cry havoc.
Ah, Trouser infernos
Paris knows how to handle those and will miss them when they're gone.
"Lithium Moss," I'm pretty sure was Kurt Cobain's first band. Apart from that, I have little of value to add (again).
For heavens sake don't tell them their smoke-detectors (installed due to overwhelming fear of fire and insurance companies) are have Americium-191 in them. Amercium-191 of course being a highly radioactive isotope, and one of the best metals to make fission bombs out of.
Now we are ALL on the teeerrrrrrssssm watch-list.
Sounds like the tin whiskers that can plague...
...lead free solders. And why aircraft manfacturers resolder lead free circuit boards with good old 60/40 before installing them.
These wiskers can reach lengths in the tens of centimetres and cause either spurious signals in the equipment, or sometimes shorts and fires.
Dendrites aren't new...
... nor are they confined to lithium cells. A few years ago it was suggested that the way to recover failed NiCad button cells was to burn off the dendrites by short circuiting the cell. I do not know of any cells (or cell owners) who survived this procedure.
To answer the question, what happens when your battery motorcycle collides with the battery car: BAVOOM!! Goodnight Vienna.
Sorry no. There are actually quite safe. Really.
I know what happens if you drop a steel spanner on the terminals of a 24V NiCad starter battery: the battery outgasses and the short circuit sets the hydrogen on fire. That's what put the guy in hospital. Should've kept the battery cover on, should've used a plastic spanner, should've been more careful, should've stayed in bed that morning.
@Matthew W - Boom
Lithium is the least flammable of all the alkali metals (sodium, potassium, rubidium, caseium and francium being the others). As it is very reactive with water and oxygen it is usually stored in oil or petrol to keep it in its unreacted state. Certainly in a closed battery cell with neither oxygen nor water present, lithium ought to be fairly stable, heat or no heat. Certainly given the proliferation of Lithium ion cells and the relative infrequency of explosion (I'm guess 1 explosion per xxx million hours of use) I'm imagining that the formation of dendrites is a fairly uncommon occurance, possibly associated with some sort of impurity getting into the material in the battery, who knows.
I found a box of old 1960's Germanium transistors, AF-117's in my loft. When I knocked up a test circuit - each transistor I tried was faulty. bit of googling led me to
which mentions that these AF117 series have mostly been 'killed' by dendritic growth.
NASA did some analysis of dendritic growth (in satellites) and found some naughty little tin crystals were able to self assemble to at least 10millimetres in length!
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