Video Shows Why Recharging Kills Batteries

sciencehabit writes with this except from Science: "You may not give a lot of thought to what happens inside the battery of your laptop or cell phone, but to judge from this video, it's not a dull place. The battery in question is a miniature rechargeable lithium-ion device, and the clip shows what happens when it is charged. As lithium ions flow from the positively charged cathode into the 200-nanometre diameter wires of tin oxide that make up the negatively charged anode, the nanowires writhe and bulge, causing them to expand up to 2.5 fold. The wires also change structure from a neatly ordered crystal to a disordered glassy material. These distortions may explain why such batteries ultimately wear down. Knowing more about the process may help researchers develop longer lasting, and perhaps much smaller, batteries in the future."

Comments

You got all that from THAT video?

[Monkeedude1212]

I keep watching it over and over again, in its 17 second glory... and I honestly wish I could believe you.

No, I'm almost positive (no pun intended) that this is actually a Rorschach inkblot VIDEO. You see whatever your subconscious is thinking about. Edwin Cartlidge is obviously suffering from the stress of a bad phone lithium ion battery - and when he stumbled across this video thats what he percieved is happening.

For me, I think this is the opening bit to a Frank Miller or James Bond Flick - I can almost hear the rock/Jazz music chime in.

What about you guys? What do YOU see?

Re:You got all that from THAT video?

[Monkeedude1212]

It says you've seen too much of David Lynch's films, which is to say, more than 10 minutes.

Re:You got all that from THAT video?

[thedonger]

That is also in TFS, but after watching the video it may just as well have said, "watch this worm."

For my fellow noscript and requestpolicy users...

[TheCarp]

The sight has a boatload of requests going all over the place... the video is hosted on "brightcove"

What we don't know why or how?

[Twinbee]

I find it pretty amazing that we don't really still understand why these things wear out. It's a bit more forgivable for something like the human brain which is much more complicated, and where we can't easily poke around for obvious reasons.

But batteries?

I'm guessing our tools to get a peak of the microscopic realm must still be in their early stages technogically.

Re:What we don't know why or how?

[jeffmeden]

We do know why, and it's simple; parts of the insides of the battery end up in different places over time. The chemical reactions that take place during charging and discharging don't happen with perfect symmetry in forward and reverse, therefore each cycle will leave a little less reactive material than before. Making a battery with such perfect symmetry might be theoretically possible but it's not been achieved with any cost-beneficial success.

The bottom line is that batteries, like many other things, are only gradually improved since the process of production that establishes their characteristics can only be gradually improved. The lithium-ion system was a LONG time coming from the days of lead and nickel, but nevertheless it's just another stop on the road to better things.

Re:What we don't know why or how?

[Twinbee]

The CRT is a mature technology too. Doesn't mean it's ideal, or nearly ideal. Anyway, see:

http://en.wikipedia.org/wiki/Transmission_electron_microscopy#Limitations

Yes a lot of the problem is holes in our knowledge of the presumably complicated battery physics, but I bet we'd have a lot more insight if these things could be analyzed and seen in realtime without any of the tedious preparation and other obstacles. Ideally, we'd even have the battery running as normal the whole time, though that may be almost impossible.

Re:What we don't know why or how?

[koolguy442]

TEM Comments
This experiment was actually quite a bit harder to carry out than you think. (I imagine, as I wasn't involved in this study but do similar work.) Doing these experiments is like traveling to the moon in that the principles are relatively simple, but it's the details that are hard. While operation of the TEM is relatively easy, preparation of samples is extremely tedious even when the sample is relatively robust and isotropic and it doesn't matter where you need to look on the sample. Constructing a TEM specimen with the intention of looking at a tiny little feature of some larger piece of material is extremely difficult, taking hours or days, if even possible. It's even more difficult to prepare a specimen and have the right equipment set up to control and observe dynamic processes, such as lithium discharge from a single nanofiber. And viewing dynamics in a complicated system, like a battery, which contains at a very minimum three active components, anode, cathode, and electrolyte, is another order of magnitude harder. Plus you have to find a way to make the thing less than 20 nanometers thick and get it into a microscope at high vacuum without breaking or contaminating it, which is nontrivial. There's also the cost of the equipment, which is between $500,000 and $10 million for the microscope itself and another couple hundred thousand dollars for the specialized probes required to do this experiment. I do this for a living myself, as do many people across the world who are either pursuing or already have PhDs in microscopy and analysis, and if it were easy, it'd've already been done and we'd be out of the job.

Battery comments
We understand pretty much exactly why batteries wear out. Though the anodes in "real" batteries are usually some form of graphite, which expands less than 10% versus the SnOx in the video (~250%), there is still jostling of all the little powders that form the battery upon charging and discharging that eventually lead to the individual particles separating from the electrodes as a whole and essentially becoming dead micro-paperweights within the battery cell. It's just very hard to image them dynamically in a realistic operation because air and water vapor tend to destroy the materials nearly instantly.

It's an engineering trade-off

[Anonymous Coward]

You can have a battery which has almost infinite charge-discharge cycles. (iron-nickel) It will be very large and heavy for the energy it stores and also has quite a large self-discharge.

If you want a small light battery that stores a large amount of energy, something has to give. In this case battery life suffers. You can make batteries that last a lot longer, they will just be big.

Re:It's an engineering trade-off

[jeff4747]

Because no one has found a material for batteries without trade-offs. All currently known chemistries maximize at best two of weight, power density and cell life.

When someone finds a material that maximizes all 3, then we get that whole 'world-changing-invention' situation.

Direct link

[qwertyatwork]

http://bcove.me/581iaz9a

Re:Positive and negative?

[cdrudge]

It depends on if the battery is charging or discharging as to if the anode or cathode is the positive or negative terminal. Read the top of the wiki page for cathod or anode for more info.

Re:Can't wait for the same on supercaps

[Anonymous Coward]

Wouldn't it be just the same system we use now, except backed by electrons (instead of fiat, or metals)?

I can't see our physical money tokens being replaced by batteries - not unless either the storage density goes up a few orders of magnitude or power prices do, and that's not counting the price of the battery itself. Power is about 10 cents per kilowatt hour. My laptop battery is, what, 60 watt hours? Even if it was 600 watt hours in the same volume and weight, that's worth less than ten cents.

Iron-Nickel Innuendo

[jdev]

Large, heavy and a lot of self-discharge? Are we talking about batteries still or Slashdot users?

Re:Can't wait for the same on supercaps

[Hognoxious]

A market based on real energy would be immune to inflation.

Why? Because it can't be created or destroyed?

You fail to see the difference between energy and useful energy. The supply of the latter certainly went up when the water wheel & steam engine were invented. If your currency was backed by energy it would crash just like one backed by gold would if you suddenly stole tons of it from a South American kingdom that you'd just conquered.