Alleviating Range Anxiety

Cornell researchers have created a new lithium battery that can charge in under five minutes — the fastest on the market — while maintaining stable performance over extended cycles of charging and discharging. You can watch this video to learn more — and charge your EV in the time it takes to do so.

Transcript

00:00:06 We've figured out, I would say, brilliantly in the last decade how to make electric cars that look good, that are reliable, that are actually, know, pretty effective as potential transition entities to this renewable energy future. The challenge is we've not figured out yet how to make them at a price point where any person can actually acquire a car just as they can with a car driven by an internal combustion engine. And if you think about why, it's not the design. The ingredient that's different is, in fact, the battery pack that powers the vehicle. And so the thought is that if we can make that pack smaller and hence less costly,

00:00:49 it would be a pretty much a, you know, potentially a game changer At a simplest level, you can think of a battery as a device that has essentially three important parts. It has a cathode, an anode, and an electrolyte. When you store charge in the battery, you essentially store material in the anode for a lithium battery. That material is lithium. When you discharge the battery, you move material from the anode to the cathode inside the battery. And that movement is accompanied

00:01:20 by movement of electrons outside of the battery cell. And those electrons drives the current, which is what provides power, for example, to light the light bulb or to move an electric car. so the current EV batteries all use a graphitic carbon as the anode, the innovation that came out of our work says well, you know, other materials could be better, especially for fast charging and in our case indium is a material of choice. It's in the same group of the periodic table as aluminum. So it's similar characteristics to aluminum.

00:01:56 It's soft, it has a reasonably good electronic conductivity. And importantly in batteries, it has very good resistance to corrosion by the electrolyte components in the battery. And what we discovered almost seven years ago is that there's really something very special about indium in that the energy gap between a lithium ion hopping from one site, an indium to another adjacent site is less than kT, which is thermal energy, which means that occurs almost spontaneously. The end result is that lithium moves very quickly, almost

00:02:35 without resistance on an indium surface and in indium as a material. And so it really struck us that this is a really special material from the perspective of creating a homogeneous distribution of lithium within the within the battery electrode. And so we decided to test it in the lab and the results are in the paper. It's an exceptional material in that it facilitates battery charging. We said in the in the paper 5 minutes, but you'll see if you read it. Some of the batteries charge in less than 2 minutes. And so it's a really amazing material. We now, of course, have to figure out, you know, how to scale it up and so on.

00:03:16 indium is pretty common. I mean but it's not cheap so it's, it's common but not nearly as common as say aluminum. So it comes at a pretty hefty cost. And so one of the things that one has to figure out, do we need 100% indium in the battery anode and could we survive with less. And this is the genesis of the work we've been doing, where we've been pairing indium with aluminum there in the same group of the periodic table, they mix pretty well. Is it possible to preserve the beneficial characteristic of indium

00:03:48 at the same time as we lower its cost by diluting it with aluminum? It is understood that with the cost of renewable electricity from solar and wind in regions all across the United States, for example, approaching values of $0.05 a kilowatt hour, which is competitive with fossil fuel generated energy that if we can figure out a solution that can store that energy cheaply, this will be the game changer in terms of society's ability to adopt renewable energy and to do it in a way that doesn't disrupt people's way of life.

00:09:29 So it's it's, it's understood by more or less everyone that right now we need a lot more storage and we needed the cost a lot less for us to be able to bring the large volumes of renewable electricity from solar and wind into widespread use. Batteries are understood to be the key and this is the motivation for what my group studies. but but in principle, you want the battery to be as light as possible, but pack as much energy as possible. Right.

00:11:58 And that is a very tough trade off because, you know, the the reality is that on a energy per unit mass basis, gasoline packs roughly about 10 to 100 times more energy than any battery that one could develop. The important difference is that a battery converts electrical energy to mechanical work at much higher efficiencies, or to 93%, compared to less than 30% for an internal combustion engine. So if you think of, you know, pound for pound energy, not just stored but energy available to do work, which is what moves the car, the battery is even heavier. It's actually quite competitive.

00:12:41 And this is in fact why we see, you know, in the marketplace, electric vehicles are still expensive, but the price points aren't outrageous. That's right. So a Chevy Volt, you can probably buy one brand new Ford at $28,000 or so a you know, a Tesla model S, you can buy for probably $40,000. And those are higher than a typical high end internal combustion engine driven car, but not outrageously higher. And we think, you know, as manufacturing and so forth take root, those prices will come down. That is a little bit of a base that is set by the fact that,

00:13:19 you know, the battery materials are, you know, pretty expensive as we speak. Now, one of the key drawbacks of indium. So in a lithium ion battery, lithium is stored in the anode and it basically gets stored in the form of lithium carbon six. So carbon has an atomic mass of 12 until six carbons are 72 grams. Indium, on the other hand, has an atomic mass of about 142. So when lithium alloys with indium, it's in a stable state. But indium lithium complex is intrinsically heavier than a lithium carbon six complex.

00:15:55 And so the end result is that one gets a battery that charges a whole lot faster, but it doesn't store as much energy per unit mass. And that is obviously important in transportation because the mass of the battery pack adds to the overall weight of the car, which in the end is an important determinant of its range. but using indium we anticipate EV charging could go from 30 minutes on a fast charger to potentially as low as 5 minutes or less. But I guess one thing I should say that I've I've I've benefited tremendously

00:22:48 from the very collaborative culture that defines Cornell. All of my students are either from materials science or chemical engineering. And as you'll see from our work, it bridges, it spans these two very important fields. And I think the secret sauce in what we do is that we're able to combine excellence in those two disciplines to solve problems in ways that perhaps weren't obvious to other persons working in this field. And I think it really does underscore the importance of bringing all mines to the table when we're solving hard problems.