The research could lead to improved batteries for emerging hybrid-electric vehicles (HEVs).
Current hybrid vehicles use nickel-metal-hydride batteries. But lithium-ion batteries have four times the energy density of lead-acid batteries and two to three times that of nickel-cadmium and nickel-metal-hydride batteries. Lithium-ion batteries may also turn out to be one of the cheapest to build.
The FreedomCAR program, initiated by President Bush in 2002, focuses on the development of hydrogen-powered electric vehicles to help free the U.S. from dependence on foreign oil. Five national laboratories — Sandia, Argonne, Lawrence Berkeley, Idaho, and Brookhaven — are involved in the program.
A key goal of the Sandia group is to develop a battery that won't cause other problems if it is damaged. Accelerated life tests are another area of research. The tests use two models to predict lithium-ion battery life: empirical and mechanistic. The empirical model uses accelerated degradation test data, while the mechanistic model relates life prediction to changes in battery materials.
Improved abuse test procedures developed at Sandia have led to lithium-ion test standards that were recently published in a Sandia research report. The group anticipates that the SAE will soon adopt these test procedures as national standards. Further, they predict that lithium-ion batteries will not only find use in gasoline-electric hybrid vehicles, but in future hydrogen-fuel-cell-electric hybrids as well.