The discovery could lead to cellphone-sized batteries that could be charged in 10 seconds.
“The ability to charge and discharge batteries in a matter of seconds rather than hours may open up new technological applications and induce lifestyle changes,” wrote materials scientists Gerbrand Ceder and Byoungwoo Kang Wednesday in the journal Nature.
In energy storage, there has always been a trade-off between the amount of energy a material could store and how quickly you could discharge it. Batteries were pretty good at storing energy (although not nearly as good as oil), but getting energy into and out of them was tough. Ultracapacitors, and their cousins, supercapacitors, can deliver a lot of charge really quickly, but it takes 20 times more of their materials to store the same energy as a comparable battery.
The new battery material appears to solve that problem by creating a “fast-lane” for ions to move around the lithium iron phosphate material. By applying a special surface coating to the old material, they allow the ions to speed around the battery at rates that are nearly unimaginable.
Rob Farrington of the National Renewable Energy Laboratory’s advanced vehicle group, called the battery’s ability to deliver energy “remarkable.”
But questions remain. Fast-charging might be convenient, Farrington noted, but it requires running a large amount of current to the battery, which he worried would reduce the battery’s life.
“High current means lots of heating. If you have high temperatures, you have to ask the question, are you detrimentally affecting the life of the battery?” he said. “The answer is that it’s going to shorten the life.”
The MIT duo’s Nature paper only presents data through 50 charge/recharge cycles, but what’s there is promising: There’s nearly no drop in capacity.
But as any laptop owner knows, the more charging cycles you go through, the less energy your battery stores. The same battery that let you work for three hours a couple years ago only yields an hour-and-a-half at the coffee shop now.
That’s one place where ultracapacitors are likely to retain their advantage over just about any battery.
“There are a lot of applications where you have to charge or discharge hundreds of times a day and in that, ultracapacitors have a very clear advantage,” said Joel Schindall, who is heading a separate MIT research effort to develop carbon nanotube-based ultracapacitors.
Still, ultracap producers, though they’ve made inroads in niche markets. have had a hard time coming up with ultracapacitors that store anywhere near as much energy per weight or volume as a lithium-ion battery. Schindall’s effort made waves in 2006 when the MIT Technology Review raved, “A breakthrough technology is holding forth the promise of charging electronic gadgets in minutes, never having to replace a battery again, and dropping the cost of hybrid cars.”
But the effort has “stretched out,” Schindall said — and he’s not sure when his ultracapacitors will be ready to commercialize.
“I don’t know whether that will be a week or a month or a year,” he said.
Batteries, and all kinds of energy-storage devices, have a notoriously difficult time scaling out of the laboratory into production. We’ve previously likened the scale challenge to that faced by high school cafeterias. Even if the lunch ladies try to emulate home cooking or a restaurant kitchen, it’s just fundamentally harder to cook for 3,000 people than it is to cook for 30 or three. Most of the time, you can’t just make the process bigger, you need a new process.
And directly tied into the ability to create an industrial-scale process is the issue of cost, which Farrington said was always one of the barriers to the adoption of energy-storage technology.
Still, Ceder is optimistic. He believes his batteries could make it to the market in two to three years. The tech has already been licensed by two companies. One, A123 Systems, is a U.S. startup that’s partnering with General Motors on the Chevy Volt’s battery. The other, Umicore, supplies materials to battery manufacturers across the world.