Behind a 2,000-pound blast door, federal researcher Peter Roth spends his days torturing electric-car batteries. He overcharges them, drives nails into them, presses them between scalding brass plates. He dunks them in salt water, sets them on fire, crushes them, drops them, dissects them. Again and again, he watches them explode.
The goal: To make sure all this mayhem happens in his lab—and not in your car. Because, as Mr. Roth says dryly, “One bad incident can spoil the public’s opinion.”
Electric cars are about to hit the market en masse: General Motors Co. plans to launch its Chevrolet Volt this fall; Nissan Motor Co.’s Leaf is slated to debut by December; and new gas-electric hybrids are in the works at Toyota Motor Corp., Honda Motor Co. and Volkswagen AG’s Audi unit. Even BMW AG has an electric compact in the works. Nearly all are powered by lithium-ion batteries, which pack six times the punch of a standard lead acid car battery and more than twice as much as the nickel-metal-hydride batteries used in hybrids such as the Toyota Prius.
Lithium-ion batteries have been around for years in cellphones, laptops and other consumer electronics. Even on this small scale, the batteries have caused sporadic trouble; several computers have been recalled in recent years after their lithium-ion batteries were found to spontaneously catch fire. Scaling up the technology enough to power a car raises fresh safety and reliability questions.
Shoestring Operation
That’s where Mr. Roth comes in. In a windowless warren of small test bays—several singed with the soot from past explosions—Mr. Roth seeks to discover what can go wrong with different types of lithium-ion cells, and under what conditions. His guiding principle? “If you build it, it can fail.”
The abuse lab is located at Sandia National Laboratories, in a high-security building mostly used for nuclear research; the reception desk displays a small sign instructing couriers: “All explosives go to Room 1107.”
Much of Mr. Roth’s research is funded by the Department of Energy, which recently awarded the lab $4.2 million in stimulus money to upgrade equipment. Auto companies and battery makers also pay the lab directly for tests on proprietary technology. “It’s our key go-to national lab for abuse tolerance testing,” says Ted Miller, a senior manager of energy storage strategy and research at Ford Motor Co.
Mr. Roth’s lab for the most part studies lithium-ion batteries—from single cells that can be smaller than a tube of lipstick to full-size automobile battery packs weighing several hundred pounds. Then there are the thin silver pouch batteries, which look fit and trim when they are new but “swell up like a Jiffy-Pop bag when they go bad,” Mr. Roth says, pulling out badly charred, misshapen pouches.
He and his research partner, Chris Orendorff, emphasize that they are testing these batteries under worst-case scenarios, often after disabling internal controls. “Then we can develop strategies to mitigate those problems,” Mr. Orendorff says. “Knowledge is power.”
The lab, whose clients also include the National Aeronautics and Space Administration, the U.S. miliary and consumer-electronics manufacturers, relies on an unlikely mix of sophisticated equipment and home-made contraptions for research.
The scientists use a state-of-the-art accelerating rate calorimeter to measure the heat generated by various types of batteries when they begin to overheat and a Fourier transform infrared spectrometer, which can cost about $50,000, to analyze the gases released as a battery breaks down after a catastrophic failure. Thanks to the stimulus funds, the lab will soon get a CT scanner, for peering inside single cells, and a thermal chamber to test how batteries react to extreme temperatures—anything from minus 70 to 200 degrees Celsius.
Yet the researchers rely on an old locomotive relay switch to perform other critical tests, such as the short circuit (a battery is hooked up and the switch is thrown closed, which causes an immediate and intense short circuit). They protect the hydraulic lines on another machine with crumpled tin foil. And their computing center looks like it was built in the 1980s and never updated. “It’s a bit of a shoestring operation,” Mr. Roth says.
Toxic Grit
With a shock of white hair, an unruly beard and impish eyes, Mr. Roth, 62 years old, looks every bit the mad scientist as he bounds through the lab reminiscing about disasters he has engineered. In one memorable test a few years back that didn’t involve lithium-ion technology, he overcharged a battery made of 48 cells lashed together, then exposed it to sparks. The cells immediately began venting a tremendous cloud of gas and then exploded like fireworks, ricocheting off walls and disintegrating so completely, nothing was left but a thick layer of grit so toxic that cleanup crews had to wear hazmat suits.
His report to the manufacturer was simple, Mr. Roth says: “Back to the drawing board.”
As for his test bay? “We put in a steel ceiling after that,” he says.
Making an Impact
Overcharging is one of Mr. Roth’s standard tests. He has repeatedly found failings in the electronic monitors that are supposed to deflect the current when the battery is full. That can cause overheating—known as “thermal runaway”—and explosions.
Armed with this data, battery manufacturers have developed a backup system of mechanical circuit breakers that interrupt the current flow when the battery’s temperature begins to climb to unstable levels.
The Sandia lab also compares the safety of various chemistries used for the positive and negative charge in a lithium-ion battery. Much of this information is confidential, but the researchers say that certain materials are clearly superior in terms of safety and that the industry is shifting in that direction.
“They’ve made a significant contribution to automotive technology,” says Menahem Anderman, president of Advanced Automotive Batteries, a consulting firm in Oregon House, Calif.
Mr. Roth’s lab has also dispelled some fears. Manufacturers worried, for instance, that if a car plunged off a bridge, its lithium-ion battery might electrify the water and shock first responders. Mr. Roth tested the scenario and dismissed the concern as unfounded.
Mr. Roth, who plans to retire this spring and turn over the lab to Mr. Orendorff, says that in more than a decade studying battery technology he has seen huge advances in safety and has been impressed by the industry’s attentiveness to his research.
So does he plan to buy a car powered by a lithium-ion battery? He hesitates. “I will certainly be inclined to buy one eventually,” he says. “But I am disinclined to buy the first of anything.”
