KEEPING THE LEAD IN

[saurabhjain]

When Edward Buiel discusses rechargeable lead-acid batteries, he speaks with the passion of a convert. Buiel is vice president and chief technical officer of Axion Power International Inc. in New Castle, Pa. After 12 years of developing large-scale lithium-ion batteries for electric cars, he thinks he has an alternative: a high-tech version of the car’s lead-acid battery. It charges faster than other lead-acid batteries and costs a quarter of the price of a comparable lithium-ion battery.

Lithium-ion batteries are the dominant power source for cell phones, laptops, and portable electronics. The problem comes when scaling them up to run a car for 50 to 90 miles on a single charge. “The battery materials have very high energy densities, pretty close to TNT, and they are very unstable,” Buiel said. “If they are exposed to air or heat, they can go into a spontaneous exothermic reaction and explode. You can make them safer, but that makes them less efficient.”

Fast-recharging lead-acid batteries may power electric vehicles.

Buiel pointed out that lithium-ion batteries are also expensive, about $800 to $1,000 per kilowatt-hour. That puts the cost of a 20 kilowatt-hour battery, large enough to drive an electric car 50 to 90 miles, at $16,000 to $20,000. “That’s why the Chevrolet Volt electric car costs $40,000,” he said. “But not every American can afford that.” A similarly sized lead-acid battery would cost $4,000, or $200 per kilowatt-hour.

The Volt, a plug-in electric hybrid, runs on lithium-ion batteries with a range of 40 miles on a charge. The car has a one-liter engine that runs a generator to power the vehicle beyond that. Comments published in 2008 said the Volt is expected to have a list price of at least $35,000 when it becomes available later this year. (General Motors was shut down when we called to confirm. A security officer who answered the phone said the company would not reopen until February.)

In the past, fast recharges were a stumbling block for lead-acid batteries, because they produce electricity by a chemical reaction that forms hydrogen sulfide on the negative electrode. The coating causes the electrode to fail, especially when recharged at high currents. It also causes swings in acidity that shorten battery life. Axion avoids the problem by making its negative electrode from activated carbon, a porous material used in ultracapacitors. The electrode absorbs and releases protons from the battery electrolyte without a chemical reaction.

This not only prolongs electrode life, but enables the batteries to charge four times faster than typical car batteries. Lead-capacitor batteries don’t have the energy density of their lithium-ion cousins, but they discharge more of the energy they store and survive more charge/discharge cycles.

The world already has an infrastructure to mine lead, manufacture lead-acid batteries, and reclaim and recycle lead from spent batteries, Buiel said. It would be relatively easy to sell improved products into the $330 billion global market for lead-acid batteries.

Axion has converted one pickup truck into a dual-mode vehicle that uses a 40-kilowatt electric motor for the front transaxle and a truck’s internal combustion engine for the rear axle. “The battery gives it a 50-mile range, and if you need to tow something, you turn the internal combustion engine on,” Buiel said. He estimated that he could produce a kit to convert pickups to battery power for less than $10,000.

The company recently received a $1.2 million grant to develop lightweight batteries for U.S. Marine Corps vehicles. “They’re not that interested in hybrids, but like that our batteries work in very cold weather,” Buiel said.

Axion can expect competition from Furukawa Battery of Yokohama, Japan, which is making a similar battery under a license from Australia’s Commonwealth Scientific and Industrial Research Organization. However, Buiel said that Axion holds the key patents on its technology.

[Myroslav Kuzko]

relevant topic about EV charging