At a General Motors research laboratory in Warren, Mich. engineers are simulating real-life wear and tear on a pair of prototype batteries that lie at the heart of GM’s riskiest technological gamble ever. By repeatedly drawing energy out and pouring it back in every ten minutes, they want to know how much stress the batteries can handle. Dialing up the torture, they’ll soon move those tests to a “shaker table,” where they will subject the batteries to jarring vibrations, extreme temperatures and corrosive road salt, to name just a few hazards.
GM is working feverishly to prove that one or both of these lithium-ion batteries will be capable of powering a hybrid car for up to 40 miles without burning any gasoline, that they’re safe and that they can last ten years and 150,000 miles. Today’s hybrids use a wimpy battery by comparison, and they can’t be plugged in for recharging. By spring GM aims to road test the batteries in prototype versions of its forthcoming plug-in, the Chevrolet Volt.
GM is sprinting to get the Volt to market by 2010 to claim first bragging rights in what it sees as a critical industry shift: the electrification of the automobile. But the year 2010 is significant for another reason. That’s when rival Toyota (nyse: TM – news – people ) says it will put its first lithium-ion battery into a plug-in hybrid. (Batteries used in cars and power tools are usually called “lithium-ion,” to distinguish them from the very different lithium batteries found in watches.)
The two companies are taking divergent approaches. Toyota, the leader in conventional hybrid vehicles, has been at work on lithium-ion batteries longer than GM. Yet it appears to be moving cautiously now, perhaps because of a rumored technology setback last summer. Its first use of lithium-ion batteries in plug-in hybrids will be limited to a few hundred fleet customers, while GM hopes to sell “tens of thousands” of the $35,000 Volt a year.
“Obviously, we are trying to bring these cars out as soon as we can. But we’d better be ready in every respect because of the bar we’ve already set with the existing Prius,” says William Reinert, national manager of Toyota’s advanced technology group. Toyota has sold 1.3 million hybrids worldwide since 1997, most of them Priuses.
GM, on the other hand, sees an opening to sprint ahead of Toyota, which recently surpassed GM as the world’s biggest auto seller. “Somebody lit a fire under [GM’s] butt in 2006,” says Ric Fulop, founder of A123 Systems, one of two companies whose batteries GM is rushing to validate. “I’ve never seen a large company move so fast and put so many resources behind something.”
Today’s Prius is like a sprinter. Its nickel metal hydride battery provides small bursts of power in stop-and-go traffic. Most of the time, however, a Prius runs by connecting a gasoline motor mechanically to the wheels.
Adding a plug and a more powerful lithium-ion battery to a hybrid can give that sprinter a bit more stamina: It can travel at higher speeds up to 10 miles or so on electric power before the gasoline engine kicks in.
The Volt is another creature yet; its wheels are connected to an electric motor. Its small gas engine exists solely to generate electricity. The Volt’s battery needs to be both a sprinter and a marathoner in power output. It has to supply enough power to get up to freeway speeds and enough energy to travel long distances. It will store 16 kilowatt-hours of electricity–enough to travel 40 miles without assistance from the gas engine. By contrast, the nickel battery in today’s Prius holds only 1.7kwh.
Carmakers favor lithium-ion batteries (already popular in cell phones and laptops) because they can store twice as much energy per liter of volume as nickel batteries. But the strain on a lithium-ion cell in a plug-in is much greater than on the batteries in today’s hybrids. That’s because the battery must be deeply discharged in order to give the vehicle maximum range. Extreme recharging of the battery, a cycle that might be repeated thousands of times over its life, can lead to overheating and the risk of explosion. (Fire is less of a worry for regular hybrids outfitted with lithium-ion batteries, because they aren’t subjected to the same deep-discharging cycles as a plug-in. Mercedes-Benz says it will use a li-ion battery in its S-class hybrid, due in 2009, and GM plans to use a Hitachi (nyse: HIT – news – people ) lithium-ion battery in its conventional hybrids beginning in 2010.)
GM considered the technologies of 27 battery makers before awarding development contracts for the Volt to Continental Automotive of Germany, which is getting its cells from A123 in Watertown, Mass., and Compact Power, a Michigan unit of Korean battery maker LG Chemical. A123 has developed a battery that uses a doped lithium nanophosphate electrode (cathode) that eliminates combustible oxygen from the system. Doping (adding the element niobium to the chemistry), as well as reducing the size of the material to nanoscale, makes it more conductive.
A123 has sold tens of millions of similar batteries in Black & Decker (nyse: BDK – news – people ) cordless power tools since 2005 without mishap. But that power tool contains only 10 battery cells versus the 200 larger ones needed to power a car like the Volt. Continental is working with A123 to develop the electronics to ensure that the cells in a Chevy Volt battery don’t misbehave.
Compact Power is using a manganese mineral called spinel that also resists giving off oxygen, says Chief Prabhakar Patil. He’s confident his battery design will deliver the 40-mile range GM demands and last a decade or more. “The major challenge is thermal management,” he says.
Toyota says only that it is looking at multiple lithium-ion chemistries, including some not yet discussed. Industry insiders say it has been developing, in a joint venture with Matsushita Electric, a lithium-ion battery that uses nickel, cobalt and aluminum dioxide. Yet the company backed away from plans to introduce these batteries in the high-volume, conventional hybrid Prius in 2009–a bit of news that had other carmakers wondering what Toyota knew that they didn’t. Some outsiders concluded Toyota faced safety issues.
Whether the tortoise or hare will win this one is unclear, but even Patil, at GM supplier Compact Power, says what many are thinking: “What I worry about is a black eye–if somebody puts a battery on the road prematurely, it would hurt the entire industry.”