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.