Ceder says the new material could reduce the weight of battery packs for plug-in hybrids by four to five times. The higher rate capability should also make for speedier charging, allowing top-offs between trips that extend the distance a vehicle could go between overnight recharges.
Other attractive features of batteries based on the new material, according to Ceder, are improved safety over other lithium-ion batteries and lower cost. Lower cost, lighter weight, and faster charging might make the batteries attractive for electric vehicles as well.
The material still needs to go through extensive testing to find out if it will have the longevity and performance capability needed for demanding automotive applications, says Khalil Amine, group leader for battery research at Argonne National Laboratory.
The MIT-SUNY research joins other recent advances in battery materials. Amine’s own work at Argonne has produced promising new lithium-ion electrodes, as has that of researchers at A123 Systems in Watertown, MA, and E-One Moli Energy in British Columbia. Meanwhile, Firefly Energy, Peoria, IL, is developing lighter lead-acid batteries that may work well for hybrids.
Developing battery packs using these new technologies and incorporating them into hybrids could take several years, as automakers perform further tests and integrate the technologies into their vehicle development cycles. Even then, the impact on fuel prices and energy consumption could take decades, as consumers gradually purchase the more efficient vehicles.
Because of this long time frame, some experts, including John Heywood at MIT, say that, to achieve shorter-term reductions in oil consumption and prices, people will have to buy cars available now that have better fuel economy. “The only things that work really fast are for people to change their buying and driving habits,” Heywood says. To encourage these changes, advocates have called for higher fuel-economy standards and tax breaks for purchasing higher fuel-economy vehicles.
Meanwhile, the MIT-SUNY computer model could help the field generally. Stanley Whittingham, professor of chemistry at SUNY, whose work led to the first commercialized lithium-ion batteries (and who was not involved with the current project), says the computer model, by showing how disorder affects materials, will help other researchers to develop new high-performance batteries. As for the new material, “In the end, to really determine whether this is a critical material, what we need is some extended cycling,” he says. “But the rate capability looks great. It looks really promising.”
Home page image courtesy of Science journal.
Caption: Lithium (in green) moves from one octahedral site (in red) to another by passing through an intermediate tetrahedral site where it encounters strong repulsion from a nearby transition-metal cation (in blue).