The holy grail for electric cars is a battery pack that can routinely deliver 300 miles of range. Tesla Motors is planning to offer such a long-range pack in the Model S sedan next year. But what if we could exceed 300 miles and deliver range beyond that of most of today's gas cars, replacing the lithium-ion technology that's standard today with something better?
That's the tantalizing promise of IBM's Battery 500 project, which as the name implies is aimed at getting 500 miles out of a charge. IBM says it has made recent breakthroughs with lithium-air batteries, but there are plenty of skeptics who say that lithium-air will never be ready for prime time.
We've been down this road before with game-changing battery technologies that look great on paper or in the lab, but then meet unmovable technical obstacles -- including the tendency to explode, catch fire or expire after a short time. Air batteries will need on-the-road validation, and they haven't had any of that yet.
Light batteries with big range
Lithium-air batteries do away with the heavy conventional compounds used as cathodes in lithium-ion, replacing them with oxygen. That results in a very light battery with the prospect of much greater energy density. But there's always been one huge stumbling block -- the batteries weren't rechargeable. Winfried Wilcke, who runs the project at IBM's Almaden Research Center in Silicon Valley, told me his lab has licked that problem, and the prospects for the air batteries are really bright:
People want to know if the batteries are rechargeable, and the answer we now know is yes. We've shown that, if we use different electrolytes from lithium-ion, then recharging works quite nicely. The fundamental operation of lithium-air is now established. This is a very substantial effort, and we wouldn't do it if it wasn't a game changer.Wilcke says IBM will have a car-sized battery ready in three years, and will then amaze the world. He thinks he can achieve an energy density of 1,000 watt hours per kilogram, which is one big improvement from lithium-ion's 150 watt hours per kilo.
With numbers like that, it's not surprising that Don Hillebrand of Argonne National Laboratory says that lithium-air
is where we're going. You can't foresee the future, but right now, that's the place where I think we see the endpoint, the end solution for--the battery. The battery everybody's looking for.That could be irrational exuberance. Doubters abound, especially in the short term. Seth Fletcher, author of the 2011 electric-car battery book Bottled Lightning, told me:
If it's true, it's a big deal and they've made a tremendous amount of progress in the last year and a half. But the establishment battery community is going to be pretty skeptical, because people have been struggling with this for a long time.It's not going to happen
Indeed, there are lots of skeptics. Lithium-air has gotten a lot of hype, says researcher Jeff Dahn of Dalhousie University in Canada, but it also has big problems. He points to the fact that lithium can react violently when it meets moisture, which is inherent in the air this technology uses to generate electricity. That requires complex membranes to allow in oxygen but keep water out.
"The whole thing is an oxymoron," Dahn said, adding that it's easy to get huge numbers on paper, but building a useful battery that's also economically viable "is something else."
And Jack Nerad, an executive market analyst at Kelley Blue Book, points out that 500-mile range is probably achievable with lithium-ion -- provided you don't mind having a huge battery that will take forever to charge and cost $60,000. Range isn't enough, he said, if battery life is short, costs are sky high and operating temperatures are a big issue.
Wait and see
There's a middle ground here. John Voelcker, an industry analyst who edits GreenCarReports.com, told me lithium-air is a technology to watch:
Lithium-air technology appears promising over the long term. But remember that taking a technology from lab results to mass-produced cells that are affordable and reliable enough to use in electric cars takes a decade or more. Automakers planning to launch plug-in cars over the next five to 10 years will all use lithium-ion cells in their battery packs. Their long-range tech guys are following lithium-air with interest, but their vehicle engineers are all about lithium-ion, and will be until 2020 or so.Wilcke acknowledges that there are many remaining issues, including lithium-air's long-term durability, and the cost at mass production. He doesn't see the batteries in production cars before 2020. But he also says he's confident that the technical issues can be overcome and that lithium-air batteries can "fulfill all the criteria necessary to make them useful in a car." OK, he's said that -- now the challenge is to prove it.
Here's Wilcke on video addressing the "Mount Everest" of next-generation lithium-air battery technology: