Better Batteries
A couple of weeks after my ill-fated attempt to test-drive the plug-in car in Washington, I’m outside the headquarters of battery maker A123 Systems in Watertown, MA. Out front is the shiny, aggressively styled GM Volt. The car is there because GM has selected A123 as one of two companies that could end up providing the battery technology for the Volt.

A123 makes a new type of lithium-ion battery. Lithium-ion batteries, which are now used widely in laptops and cell phones, pack a lot of energy into a small space. They take up just one-sixth the space of the lead-acid batteries used in previous types of electric vehicles, and they weigh one-sixth as much. They also take up less than half the space of nickel-metal hydride batteries, the kind used in today’s conventional hybrids, while weighing just a third as much.

But the type of lithium-ion battery that’s used in laptops and cell phones has problems, including the occasional tendency to overheat and, in rare cases, burst into flame. Troubling as this instability is in personal electronics, it could be even worse in a car, which uses a module that consists of hundreds of times the number of batteries found in an electronic device. On top of that, although prices have been coming down gradually, lithium-ion batteries are still expensive.

All that could change as a result of A123’s batteries, in which electrodes based on cobalt oxide have been replaced with iron phosphate electrodes. At relatively low temperatures, oxides release oxygen, which can drive reactions that might heat up a battery and cause it to explode. But phosphates continue clinging to oxygen at much higher temperatures. What’s more, iron is far cheaper than cobalt.

Volt or Bolt?
There is a giant “if” in all this, though. To become practical and economically viable, plug-in vehicles will need to be mass-produced.

Will automakers follow through on their highly publicized announcements about plug-ins? GM, for one, has a reputation for quitting on innovative engineering; the company’s executives scrapped an earlier all-electric vehicle. And even though GM had an early lead in conventional hybrid technology, it failed to bring hybrids to market until after the success of Toyota’s Prius. What will happen to plug-in plans if gas prices drop, or if interest in reducing greenhouse gases wanes?

No one can predict the results of the carmakers’ fickle decision-­making process. But a few things are clear. Plug-ins are the most practical and enticing alternative to the ­internal-­combustion engine that has been developed in years. And their fate will depend on whether automakers learn from the success of conventional hybrids and fully embrace the new technology.

I did at last drive a working plug‑in. The converted car glided noiselessly along the streets of Boston as I eyed a gauge that estimated my mileage at more than 150 miles per gallon. But on the day that I saw the Volt on display at A123’s offices, GM wasn’t ­giving rides; the car was just a mock-up, without the new batteries. As I sat in the driver’s seat and grasped the steering wheel, sunlight streaming through the clear roof, it was easy to believe that plug-ins are on the way. But the mock-up was also a harsh reminder that when it comes to green innovation, U.S. automakers have long been more eager to show off flashy concept cars than to manufacture vehicles that work.

Kevin Bullis is the nanotechnology and materials science editor at Technology Review.