Scientists develop lithium-ion battery that charges 120 times faster than normal | Hacker News Reader

Scientists develop lithium-ion battery that charges 120 times faster than normal

extremetech.com

47 pointsevo_921 comments

This is like my gimmick at this point every time there's an extremetech.com battery article...

Here is the much better/more-detailed article at GCC: http://www.greencarcongress.com/2012/08/cho-20120816.html

To me the interesting part isn't that it charges so fast, there have been LTO chemistries that charge plenty-fast for a while, but that its density is nearly double. We're now seeing multiple labs and vendors producing 300 - 400 wh/kg results. Expectations even just a few years ago were that we'd only be in the 250 range by now (where tesla is at).

Every time I see a headline like this I sigh and think, now it would be news if a manufacturer developed a lithium-ion battery with this charge rate. Because of course the difference between 'proof of concept' and 'product' is sometimes an uncrossable chasm.

That said, the article does point out the challenge of sending 56kWH to charge a Tesla in 1 minute. In case you are wondering that is a 3.36MW power draw for one minute. I can assure you that if we have an easy way to make stations that can deliver 3.3MW continuously for a minute at a time that the future of laser weapons is extremely bright (pun intended).

Now charge your phone or laptop in a minute, very cool. Too bad that the it makes the unit 3x thicker.

Just to give some numbers here: Assuming 600 volts (which is the highest rating for voltage I've seen in a commonly available wire) you would be sending 5600A down that wire.

That would require a wire 2 inches thick (1 inch radius), not including the insulation. I doubt most people would even be able to lift such a wire.

A 15 foot length would weigh 416 pounds! (Assuming no ground - with a ground it's 625 pounds.)

Is that the continuous rating, though?

Welding cables for intermittent duty are rated for higher currents, I think.

Yeah, it'd heat up, but it would have plenty of time to cool off in between charges. You'd need to arrange things so that there was absolutely no way for the user touch the hot contacts and of course use high-temp insulation throughout (which welding cables already have).

You'd want a docking station type of arrangement rather than a cable, I'd think -- maybe with some sort of clamp to really mash the contacts together. Arcing would be bad. :-)

Certainly you couldn't run it off a normal wall plug. A big capacitor bank, maybe.

It's the 90c rating.

Got some new numbers after checking welding cables, looks like 1/2 inch radius will do, I calculate weight of 128 pounds for 15 feet, which is "better" - but still completely impractical.

Only if you're using cables. No one would do that. You'd have a solid docking station with fixed, solid contacts, as I (and the person with the post immediately above yours) said.

You can use solid, fixed contacts at any temperature that won't melt the copper (assuming that they're well away from anything flammable).

You still need cables inside the car. Maybe not 15 feet, but that much weight is impractical.

If you really wanted to do this the only practical way is to increase the voltage - but of course high voltage is much harder to do safely.

I think the only practical way to do something like that would be a couple of 12" diameter copper cylinders embedded in the floor connected to either a flywheel bank or a capacitor bank. Then your car would have a very large connector contact at the front and back. (and if it had a plastic pin that went into a groove in the road you would have a life sized slot car :-))

There is actually a lot of research on going in high current, short duration, energy systems. The one I am the most familiar with (which is to say read some of the papers) is EMALS the electro-magnetic aircraft launching system that is part of the 21st century X-carrier effort. That system is looking to replace the steam catapult on todays launchers with what is essentially a rail gun type device. Lots of advantages if you can make it work (like programmed acceleration profiles) but hard to make work. They were using flywheels spun up to 10,000 rpm to store energy as angular momentum and then dumping it into the rails with a genset attached to the flywheel.

You could use a superconducting wire. (Yes, I know what you're about to say).

Might be feasible. You only need enough liquid nitrogen to keep the superconductor cool for a minute. Apparently, the Holbrook supercondcutor Project (http://en.wikipedia.org/wiki/Holbrook_Superconductor_Project) has been using superconductors in the Long Island power grid for years.

> (Yes, I know what you're about to say).

Please don't do this. If you know what the 'obvious' objections are, please say what they are. People unsure what the reasons for not doing so learn something. I'm certainly not aware of all the problems involved in using superconductors.

Superconductors don't do well with high currents so it's not a slam dunk, although they would definitely be lighter than regular copper conductors.

But don't forget the wires inside the car.

I have to imagine that the heat dissipated during a 120C charge cycle would be astronomical. Before I'll believe any claims about the practicality of this charging method... I'd want to see data about heat management.

I know almost nothing about battery tech, but I suspect this device will decharge about as fast as it charges (corrections welcome).

If so, you could slowly load a huge battery at a pumping station, or a car-size one in your home, and use that to quickly charge the ones in cars. The energy loss in such a setup could be prohibitive, though.

Or it slowly charges capacitors at your house and then you fill up the car rapidly.

Other factors, such as the battery’s energy density and cycle life seem to remain unchanged.

I might have confused different battery techs but isn't the main issue with lithium-ion that heat kills it? And that typically the heat generated when charging is the main thing limiting it's useful life?

If so, claiming that its cycle life remains unchanged seems quite optimistic.

You're right but drawing the wrong conclusion.

The heat that's produced as the battery charges is a byproduct of the resistance of the chemistry. So when you get a more efficient chemistry it increases both cycle life and charge rate, they're two symptoms of the same property. Its a win/win not a tradeoff (although you can still chose to tradeoff one for the other in your product design).

I am thinking that the current needed to charge an electric car battery that fast would likely be far to high for a residential electric system (at least ones in houses that have already been built).

With those sort of charging times it seems feasible that you could go back to the "gas station" model though: Pull up, plug in, eat a hotdog, drive away.

When you're home you probably won't have any need for a fast charge anyway.

There's two ways to tackle that - either stick to the slow overnight charge, or have a home charging station with a stonking great capacitor bank which itself recharges slowly while you're out driving.

Another way:

Have a standardised battery pack, that can see duty in a multitude of applications, for example: part of a home solar installation, or in a car. Have a control system that allows multiple batteries to be combined, in a hot swappable manner, within a single installation.

Advantages:

1) Economies of scale allow lower battery price, since the same pack is used everywhere.

2) Common form factor allows batteries to be physically swapped (instant recharge for a car).

3) Redundancy, if one battery breaks, the system can keep working, with reduced capacity, until a replacement is bought.

4) With the right control system it should be possible to transfer energy between batteries as required, allowing the car to be charged in-situ from the house, or the house to take energy from the car, if needed. The car can even be used to transfer energy from an external source into the domestic setting, the electrical equivalent of an oil tanker.

5) More efficient use of available capacity, by combining all batteries into a single system, they will be used more often, rather than sitting unused while people sleep or drive.

I believe this is the citation referenced. [1] It's unfortunately under a paywall.

[1]: http://onlinelibrary.wiley.com/doi/10.1002/anie.201203581/ab...

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