[News] Flameproof Lithium batteries developed

[StyM]

http://www.fudzilla.com/news/44470-f...ries-developed

A team of Americian Army boffins have emerged from their back-rooms with lithium ion batteries that are resistant to exploding or catching fire.

According to the science journal Joule, which we get for its join the dots puzzle, the devices produced sufficient energy for use in household electronics, but did not ignite -- even when punctured repeatedly with a nail.

The batteries use a water-salt solution as their electrolyte, removing the risks carried by some non-aqueous commercial models.

The report said: "In the past, if you wanted high energy, you would choose a non-aqueous lithium-ion battery, but you would have to compromise on safety. If you preferred safety, you could use an aqueous battery such as nickel/metal hydride, but you would have to settle for lower energy."

The report's co-author Kang Xu works for the US Army Research Laboratory (ARL). He said that the invention means that you can simultaneously have access to both high energy and high safety. Of course this is too late for Samsung, which last year saw an entire top of the range phone disappear from the market over allegations that a faulty battery caused fires.

[madmaxx]

Until they test it in a Samsung it's not flame proof.

[Particle]

Throw away all lithium cobalt chemistries and use lithium titanate already. Problem solved.

[Sparky]

Why don't you go make those then and market them? And make big money?

[StAndrew]

Why don't you go make those then and market them? And make big money?

Because they have a lower inherent voltage and capacity.

[Particle]

Not an easy sell for consumers who constantly about insufficient capacity. I'd trade some compactness or runtime for a phone that doesn't explode or a car whose batteries don't wear out for two decades, but somehow I'm the outlier. Also, they exist already.

[bluestang]

I remember watching a special on PBS's NOVA about this...

Excerpt:
http://www.pbs.org/wgbh/nova/tech/ba...t-explode.html or https://www.youtube.com/watch?v=m9-cNNYb1Ik

Full Program:
https://www.youtube.com/watch?v=ffh8Nxe_zAo

[StAndrew]

Not an easy sell for consumers who constantly about insufficient capacity. I'd trade some compactness or runtime for a phone that doesn't explode or a car whose batteries don't wear out for two decades, but somehow I'm the outlier. Also, they exist already.

With a much faster charge, I probably wouldn't mind giving up some capacity. I think the lower voltage might be an issue though. If you can get it to run at 3.7V, I'm sure the market can find a place for them.

[Particle]

With a much faster charge, I probably wouldn't mind giving up some capacity. I think the lower voltage might be an issue though. If you can get it to run at 3.7V, I'm sure the market can find a place for them.

Cell voltage is a property of the choice of anode and cathode materials. If you want to change the cell voltage, you have to change materials (and thus change battery types). There isn't much you can do about it for any particular chemistry. Higher characteristic voltages do typically imply higher energy density, but not necessarily so. The cell voltage by itself doesn't really present any sort of functional problem.

[Sparky]

Really, exploding batteries are few and far between in the grand scheme of things. What, we had bad Sony cells many years ago in Dell and Apple laptops, and then the Samsung Note last year as the only real major ones. It isn't like exploding Li-ion batteries are that common when looking at the entire picture.

Not sure how much less capacity the other type you're suggesting has, but if it halves the battery life that's an issue, especially if they don't charge fast.

[Particle]

Really, exploding batteries are few and far between in the grand scheme of things. What, we had bad Sony cells many years ago in Dell and Apple laptops, and then the Samsung Note last year as the only real major ones. It isn't like exploding Li-ion batteries are that common when looking at the entire picture.

Not sure how much less capacity the other type you're suggesting has, but if it halves the battery life that's an issue, especially if they don't charge fast.

Lithium chemistries exist on a spectrum of stability. The less stable the chemistry the more capacity you get. They suck at everything else.

The spectrum goes something like this. Low stability offers maximum capacity, lowest charge currents, lowest discharge currents, lowest thermal runaway safety margin, lowest failure mode safety, and lowest cycle life. This is typically the sort of cell that is put into portable consumer electronics. High stability offers the lowest capacity (of lithium family chemistries), highest charge currents, highest discharge currents, highest thermal runaway safety margin, highest failure mode safety, and highest cycle life. The market has driven us to cruddy cells because people complain about battery life.

For applications that don't necessarily require high volumetric density such as an electric vehicle (ie it's not a "portable" device), you will often see something from the middle of the spectrum such as lithium iron phosphate. These cells can accept higher charge currents, can provide higher discharge currents, and have about 10x the cell cycle life as compared to the type of cell that is in your phone.

I'd like to see us skip to the other extreme of the spectrum on the polar opposite end from lithium cobalt. This is where lithium titanate lives. It offers even higher charge and discharge currents than lithium iron phosphate and about 10x yet again the cell cycle life. The cells are stable enough that you can drive a nail through them or crush them in a hydraulic press and they don't catch on fire or explode. They have about 100x the durability of lithium cobalt cells and can be charged at truly obscene currents.

To summarize as a more direct response to your statement, yes they have something like half the volumetric energy density but no they don't charge more slowly. They can be charged much, much quicker because they're more stable.