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Volt's Battery Capacity Could Double

Feb 06, 2011 - Technology Review

GM has tipped its hand about the type of battery materials it aims to use in the next generation of the Chevrolet Volt and other battery-powered cars. It has licensed battery-electrode materials developed at Argonne National Laboratory, a U.S. Department of Energy Lab. These materials, called mixed-metal oxides, could improve the safety and durability of car batteries and help double their energy-storage capacity, potentially leading to substantial costs savings by allowing GM to use a smaller battery pack.

Cost is the biggest problem with the wave of battery-powered vehicles that started to arrive on the market last month. GM's Volt, an electric vehicle that goes 35 miles per charge and has a gasoline generator for longer trips, costs more than twice as much as a similar-sized conventional car, in large part because of the battery. Increasing the amount of energy that a battery stores allows an automaker to use a smaller battery pack, thereby reducing costs.

"The whole concept of improving energy density is the prize when it comes to these kinds of vehicles," says Jon Lauckner, president of GM Ventures, GM's venture-capital arm. He says it's not clear yet how much money the new technology will save, but "suffice it to say, it is significant; it is not a single-digit percentage."

The current model of the Volt uses lithium-ion batteries made with lithium-manganese spinel cathodes ("spinel" refers to the three-dimensional arrangement of atoms in the material). The Argonne patents that GM has licensed cover a cathode material that consists of lithium, nickel, manganese, and cobalt. The material has both active components, through which lithium ions move when the battery is charged or discharged, and inactive ones that help stabilize the active material and extend battery life. Longevity is essential for electric-car batteries, which are designed to last for a decade and have to survive harsh conditions on the road. The new material has such high energy density because it can operate at a higher voltage than current electrode materials and also store more lithium ions.

The patents cover a range of nickel-manganese-cobalt materials, including new variants that GM and Argonne are developing and some components of the current Volt battery electrodes, which is made by LG Chem, a Korean manufacturer. The company has been able to use the materials because the Argonne patents only apply in the United States. But now LG Chem is building a battery-manufacturing plant in Michigan and must license the intellectual property from Argonne for use in products made there. Other companies such as Sharp are also commercializing batteries with nickel-manganese-cobalt electrodes, but of types not covered by Argonne's patents.