General Motors Co., maker of the Chevrolet Volt plug-in hybrid that is the subject of a federal safety probe, is moving to a less volatile battery chemistry for its Chevy Spark electric car going on sale in 2013.
GM is using phosphate-based lithium ion batteries from Waltham, Massachusetts-based A123 Systems Inc. that are less likely to burn than other lithium chemistry, including that used in the Volt model introduced last year, said battery experts and suppliers.
The move by GM and other carmakers to different battery chemistry a year after the Volt and Nissan Motor Co.’s Leaf went on sale highlights how quickly the technology is changing for electric and gasoline-electric hybrid cars.
GM and other companies are engineering future models with lithium phosphate technology partly because the batteries can be safer and last longer, said James Hall, principal of consulting company 2953 Analytics Inc. in Birmingham, Michigan. Battery makers weren’t ready to mass-produce them until recently.
“Lithium phosphate chemistry looks like it could be more friendly in terms of heat management,” Hall said. “But it stores less energy. There is a tremendous amount of new discovery. This is new territory for lithium batteries.”
The Volt, which uses different technology, is being investigated after three batteries caught fire since May following government crash tests. The National Highway Traffic Safety Administration’s probe isn’t centered on battery cell chemistry, said Randy Fox, a spokesman for Detroit-based GM.
The probe is focused on pack design and any fix would likely involve the pack, he said in a telephone interview.
GM chose A123’s battery for the Spark “based on their performance to our packaging, performance, quality, cost and safety specifications,” Fox later said in an e-mail. “We did not select A123 solely on its battery chemistry.”
The automaker announced the deal with A123 in October, about four months after the first Volt battery caught fire. A123 had placed a bid to supply batteries for the Volt, losing out to South Korea’s LG Chem Ltd., said Andy Chu, vice president of marketing for A123.
When GM and Nissan were taking bids for batteries for the Volt and Leaf years ago, suppliers didn’t have proven production for lithium phosphate technology. GM, Nissan and Palo, Alto, California-based Tesla Motors Inc. instead chose batteries with lithium metal oxide technology.
Now suppliers are ready, and carmakers are starting to choose lithium phosphate, said Jay Whitacre, assistant professor in materials science at Carnegie Mellon University in Pittsburgh.
All lithium ion batteries can catch fire because they have flammable electrolytes in the pack, he said. Lithium batteries, like gasoline, are combustible under certain conditions. Lithium-ion batteries are safe, while some are less likely to burn than others, he said.
Lithium batteries can burn if steel pierces the casing and stays in contact with lithium. If the battery isn’t discharged and handled properly, the temperature can begin to rise until there is a fire.
GM developed protocols for handling the Volt battery after the June fire that started the U.S. probe, the company has said.
There are trade-offs between the two technologies. While no lithium ion batteries are fireproof, lithium metal oxide batteries can catch fire more easily, Whitacre said. When they get too hot, the ceramic structure that holds the oxygen releases it. That oxygen can feed a blaze, Whitacre said.
NHTSA started its investigation after a Volt caught fire three weeks after a side-impact crash test May 12 while parked at a testing center in Wisconsin. Volt battery packs were damaged in three more tests in November, causing two fires, NHTSA said Nov. 25. NHTSA isn’t investigating Nissan’s Leaf or Tesla’s Roadster.
Manufacturing quality, as well as the design of the cells and the pack that bundles them, play a big role in determining how safe batteries are, said Menahem Anderman, founder and president of Total Battery Consulting Inc., in Oregon House, California. There is no guarantee that any lithium ion batteries will be completely safe, Anderman said in a phone interview.
Storing Less Energy
With phosphate, it’s more difficult for a fire to spread from cell to cell, said Robert Kanode, CEO of Valence Technology Inc., a lithium phosphate battery maker in Austin, Texas.
The trade-off is that lithium phosphate batteries store less energy and would have to be bigger, Kanode said. Carmakers can get more range or better acceleration using batteries like the Volt’s lithium manganese battery.
That’s one reason why Valance has focused on commercial applications like United Parcel Service Inc. delivery trucks and double-decker buses in London, Kanode said. It’s easier to package larger lithium phosphate batteries in those vehicles, he said. If Valence made a battery for the Volt, it would be as much as 10 percent larger than LG Chem’s battery pack.
In addition to the Spark, Fisker Automotive Inc. will use lithium phosphate batteries for its Karma sports car. Bayerische Motoren Werke AG is buying lithium phosphate batteries from A123 for its ActiveHybrid 5 and ActiveHybrid 3 models, the first of which goes on sale in March, A123’s Chu said.