German built: The T-shaped pack (above) holds A123’s battery cells. GM is testing the pack under simulated driving conditions before bolting it into an electric-vehicle prototype.
Charging Up Cars
Meanwhile, GM was rethinking its technology strategy as Toyota began to dominate the hybrid-vehicle business. A hybrid uses a battery only part of the time, relying on a gasoline engine for much of its power. GM decided to develop a car that would allow its customers to stop using gasoline entirely for most daily driving. But to pull it off, the automaker needed a high-performance, reliable battery. And for that it turned to A123.
GM knew that it wanted to use lithium-ion batteries because of their storage capacity, says Denise Gray, GM’s director of energy storage systems. But it also knew that existing technology wouldn’t do the trick. Though a lithium-ion laptop battery might survive 500 complete charge-and-discharge cycles before its capacity fades, no car owner wants to buy a new battery every 18 months. According to A123’s projections, however, its batteries should be able to deliver more than 15 years’ worth of daily charges. And in addition to being safer than other lithium-ion batteries, A123’s operate at a lower temperature, which makes it simpler to pack hundreds of them together into a large battery pack, Gray says.
Where A123’s power-tool batteries are cylindrical, the battery it developed for the Volt is flat, to save space and more efficiently dissipate heat. The cells have been assembled into complete battery packs, which are T-shaped and nearly two meters long. This spring, the batteries will be bolted into vehicle prototypes for road testing. And later this year, A123 plans to increase production of the batteries to meet anticipated demand. The first cars powered by A123 technology could be rolling off assembly lines in 2010. (GM is also testing batteries from another company, and may use batteries from either or both companies.)
If the Volt is popular, electric cars could finally start to take off–and that could reduce greenhouse-gas emissions and petroleum consumption. A recent study by the Electric Power Research Institute and the Natural Resources Defense Council suggests that electric vehicles similar to GM’s car could eliminate billions of tons of greenhouse-gas emissions between 2010 and 2050. A study by General Electric indicates that if half the vehicles on the road in 2030 are electric-powered, petroleum consumption in the United States will shrink by six million barrels a day.
And batteries like A123’s could have repercussions far beyond the Volt. Even cars with internal-combustion engines are being engineered to rely more on electricity: the simplest examples involve batteries recharged by souped-up alternators that would allow a car to shut off its engine when it approaches a stoplight and restart when the driver hits the accelerator. In conventional hybrids, versions of A123’s batteries can deliver as much power as nickel-metal hydride batteries at one-fifth the weight. The new batteries could also benefit plug-in hybrids, which can be recharged from a standard electrical outlet. Indeed, A123’s batteries may be used in a plug-in version of the Saturn Vue hybrid SUV that’s due out in 2010.
Whatever their design, future cars will be likely to rely much more on electricity. “We’re not there yet,” Chiang says. “There aren’t Volts all over the place. But the potential to have a big impact, both on the oil supply issue and greenhouse gases–I didn’t imagine that we’d be able to do that. Certainly not when I started working on batteries.”
Kevin Bullis is TR’s Nanotechnology and Materials science Editor.