The lithium-ion batteries in first-generation electric vehicles bring much better performance than other types of batteries now used in hybrid vehicles. But that’s just the beginning. Researchers who are studying new Li-ion technologies expect much higher performance from them, though these benefits won’t come without a fair amount of development.
Li-ion batteries offer much better energy density than the nickel metal-hydride batteries used in many hybrid vehicles. Most automakers are basing new designs on Li-ion, which already come in many different versions that use materials such as manganese and cobalt. Expectations of significant Li-ion market growth are fueling worldwide research.
One of the main goals of that research is greater energy density.
“We need to drive down costs and increase performance,” said David Howell, Team Lead for Hybrid and Electric Systems at the U.S. Department of Energy. “Today’s technologies are just kind of a down payment to get us into the market.”
That’s a view shared by battery researchers who recently gathered in Illinois for Argonne National Laboratory’s Fifth International Conference on Polymer Batteries and Fuel Cells.
“Li-ion batteries are not yet at such a technological level to meet the power requirements of efficient hybrid or electric vehicles,” said Bruno Scorsati of the University of Rome Sapienza.
Scorsati addressed the latest research in two technologies that are currently getting much attention in research labs: lithium sulfur and lithium air.
In principle, they provide three to five times more energy density than today’s commercial Li-ion technologies. But bringing that capability into the mainstream will require much more development.
Jung-Ki Park of the Korea Advanced Institute of Science and Technology focused on research that will make Li-air batteries viable. They currently suffer from a handful of technical challenges that makes them “far from materialization.” Korean researchers are focusing on new materials for electrolytes and separators as well as improved lithium anodes. Their efforts go down to molecular levels, including pore size within carbon cathodes, as do other global R&D projects.
Argonne’s conference lineup included researchers from Japan, Canada, and several European countries. Though they all focused on advanced technologies, speakers generally agreed that existing batteries provide enough benefits to help build up the infrastructure for both battery manufacturing and electric vehicle recharging.
Howell noted that the U.S. market could exceed 1 million plug-in vehicles by 2015. “Cumulatively, if the automakers' plans come to fruition, we could hit 1.2 million in 2015,” he said.
In the U.S., much of the government-funded R&D is performed by three DOE groups: Basic Energy Sciences, Advanced Research Projects Agency-Energy, and the Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Program. They have a $94 million budget for fiscal year 2011, with EERE getting the bulk of the funding. Teams meet every few weeks to ensure that all three are current with developments and to prevent overlap, Howell noted.
The DOE research labs are working on long-term technologies. “My goal is to get these technologies to the point that automakers may pick them up in 2020,” Howell said.
Reducing dependence on imported oil is an important driving factor for the research. Howell noted that transportation accounts for about 80% of the 19 million barrels of oil used in the U.S. every day. Though vehicle miles driven every day have doubled in the U.S. since the 1970s, worldwide oil production has not risen since 2005. If electrified powertrains garnered 10% of the market by 2030, the daily savings could be 1.2 million barrels of oil, he said.