10 min charging time for new e-car battery
Governments in many countries are on a drive to encourage the use of electric vehicles to cut pollution. In the UK we have the ambitious target of ceasing the sales of new petrol and diesel cars before 2030. The problem is that the present generation of electric vehicles are very expensive, and most of the cost is the battery. There’s also the disincentive of the slow recharge times, that can be hours in some cases. So we welcome news from engineers at Pennsylvania State University who have developed a new battery technology for electric vehicles that - they say - is cheap, gives you decent range, and can recharge in under ten minutes! They’re using a technology called lithium iron phosphate that the industry had largely moved away from, because at regular temperatures it stores less energy than other types of lithium batteries. But researcher Chao-Yang Wang has come up with a couple of clever tricks to make it work - as he told Phil Sansom...
Chao-Yang - We created a low cost battery that can be rapidly charged, and also significantly reduce the battery cost so that, you know, average people can afford electric vehicles.
Phil - It's a pretty impressive claim. How have you done all of this?
Chao-Yang - Well, we have been working on batteries for 25 year,s and in the last five years or so, we made a major breakthrough in terms of adding this self-heating function into the battery.
Phil - Self-heating. Does that make it charge quicker because the chemistry becomes more efficient or what?
Chao-Yang - Self-heating is basically accelerating the chemical kinetics, the movement of lithium ions between the two electrodes, anode and cathode. We typically would raise the cell temperature to about 60 degrees Celsius.
Phil - How does this heating process work? Because this must take a bit of energy itself, right?
Chao-Yang - Sure. So what we did is basically, we invented a very elegant self-heating structure, which consists of a nickel foil, very thin, 10 micron thickness, nickel foil.
Phil - Nickel metal.
Chao-Yang - Yes. And then insert that into the battery, because the battery has the energy. So you really don't need any external heat source, this well cause internal heating, extremely efficient and fast.
Phil - Isn't the problem with these car batteries that previously, when they've heated up, you get this sort of catastrophic chain reaction? And that's why you hear stories of car batteries, catching fire, little explosions, that kind of thing. How have you avoided this enormous problem?
Chao-Yang - Yeah. You have an excellent point, and typically battery materials are afraid of the high temperature. So the trick we play here really, is to maintain the elevated temperature only for about 10 minutes per charge. So think about it, after your charge, you have about 200 to 300 miles. So for every 200 to 300 miles, you only have 10 minutes exposure to this elevated temperature. So you have limited material degradation, and that is how we balance the ability to fast charge due to high temperature, and suppressed material degradation at the high temperature.
Phil - What about this other claim that you've told me about that it's, you know, pretty low cost, where's that coming from?
Chao-Yang - So once you have the fast charge ability, you will be able to downsize the battery on your vehicle, and smarter batteries, lower cost. We also use low cost materials, and we use a lithium iron phosphate as a cathode, which is thermally, extremely stable and safe. So with these two aspects, smaller size, and the use of cheap materials, we will be able to drive the cost down to about $3,500 per vehicle, on par with gasoline engines.
Phil - So all good news. Have you put this in a car yet?
Chao-Yang - No, not yet. I think the next challenge is working with automakers and battery manufacturers.
Phil - Okay. Do you know it will actually work in a car?
Chao - Yang - Yeah, I think so, because this low cost thermally modulated battery is fundamentally based on the self-heating structure, which has been used to produce an earlier product, called the All-Climate Battery. And that earlier product, the All-Climate Battery, has been used in cars.
Phil - Okay. How long until I can buy this?
Chao-Yang - My batteries, I think will be in the marketplace, in around three to five years.
It’s unclear whether the high temperature charging will degrade the battery over the lifetime of a car, so we’ll keep an eye on that.