What's Wrong With Lithium Ion Batteries?

An anonymous Coward writes "Lithium ion batteries short-circuit. They overheat. They burst into flames. The reasons behind the recent spate of problems with a technology invented by Sony more than a decade ago are complex and varied, making for one big engineering headache."

Comments

Some stuf I wrote on this a while ago

[Groo Wanderer]

http://www.theinquirer.net/?article=14417

I wrote that before batteries going boom was the latest fashion trend. The problem is simple, you have a lot of energy in a small area and people crying out for higher densities. If _ANYTHING_ goes wrong, you have a high likelihood for a lot of energy released in a short amount of time.

Couple this with reactive/flamable substance that make up batteries, and you have a lightshow. There is no magic to it all, simple physics. Lots of energy released around reactive things, you need both for a modern battery.

Some designs minimize the risk, none remove it. As always, nothing new under the sun.

                -Charlie

Fortunately

[evanbd]

Fortunately, we have supercapacitors. While they're not there yet for energy density (still about 10x too little) they're rapidly improving. 10x isn't much at the rate these things have been improving, and there are plenty of labs with pieces that are much better than currently available commercial offerings, but that still need development work. If I had to guess, I'd say it's 5 years until the first supercaps appear in serious commercial use, and less than 10 until LiIon has gone the way of NiMH.

Of course, if you believe the rumors then it might be even faster than that -- we might be seeing serious applications in a year or so.

I, for one, will be glad to give LiIon a proper burial. But until then, we work with what's available.

Re:They only started doing this recently

[Hal_Porter]

I found an interesting article that supports that theory -

http://www.electronicsweekly.com/blogs/engineering -design-problems/2007/09/whats-wrong-with-lithiumi on-ba-1.html

But Don Sadoway, a professor of Materials Chemistry at MIT who is an expert in advanced battery technologies, worries about off-shoring of a chemistry he asserts "needs to be treated with respect."

"I have 100% confidence in the Japanese battery manufacturers," he says. "And my guess is that they never had the problems theyre seeing now when the same batteries were manufactured from start to finish in Japan."

He notes that one of the challenges with Li-ion batteries in particular is that it is very difficult to verify that the manufacturing and assembly is being performed according to specifications. Thats because once its assembled into a battery pack, the device cannot be inspected from the outside nor can it be easily tested.

Sadoway points to the separator material between the electrodes as an example. Acting like a kind of fuse, it is designed to soften and collapse at a specific temperature, causing the battery to essentially go into an open circuit condition and die.

In fact, he wonders why that didnt happen in the case of the Dell laptop that burst into flames last year.

"You could think you are specifying a porous polypropylene material for the separator, but once the thing is packaged up you would have no way of knowing what you actually got. Even under the best of circumstances, you can get screwed by your own job shop. What if the workers took a short cut and substituted the original material with cardboard?"

Even better there's a link to that article in the writeup! Pretty handy.

Re:What's wrong? They store to much energy!

[Eivind]

It's inherently dangerous because very high energy-densities nessecarily mean that there's a lot of energy there to be released. Also, everything for that reaction to occur, must be contained inside the battery. (well, if you exclude air-breathing batteries)

It can be made more or less safe, but normally at a cost of reduced energy/pound. This ain't just so for batteries, but for literally *anything* storing large amounts of energy.

Natural gas has certain failure-modes that are ahem, unpleasant. The failure-modes become more likely as you increase the pressure and/or decrease the mass of the container used to hold the gas.

A flywheel used to store a large amount of energy would be unpleasant if it where to ever disintegrate, get out of balance, or somehow drop out of the bearings. All of which become more likely the higher the energy stored and the less material used for securing against these possibilities.

And yeah, batteries, especially those with high energy-densities, have unpleasant failure-modes. If you where willing to accept a twice-as-heavy battery with the same energy-content, these could be made less likely. Hell, even if you where willing to pay more for an equal-capacity battery, the failures could be made less likely. Still, they're always gonna be there.