The MIT team’s new lithium battery contains manganese and nickel, which
are less expensive than cobalt that is used in today’s lithium-ion
batteries. Lithium nickel manganese oxide, described in a paper published
in Science on Feb. 17, could revolutionize the hybrid car industry -- a
sector that has "enormous growth potential," said Gerbrand Ceder, MIT
professor of materials science and engineering, who led the project. Other
potential applications for the new lithium battery include power tools,
electric bikes, and power backup for renewable energy sources.
"The writing is on the wall. It’s clearly happening," said Ceder, who
said that a couple of companies are already interested in licensing the
new lithium battery technology.
The new material is more stable (and thus safer) than lithium cobalt
oxide batteries. The small safety risk posed by lithium cobalt oxide is
manageable in small devices but makes the material not viable for the
larger batteries needed to run hybrid cars, Ceder said. Cobalt is also
fairly expensive, he said.
Scientists already knew that lithium nickel manganese oxide could store
a lot of energy, but the material took too long to charge to be
commercially useful. The MIT researchers set out to modify the material’s
structure to make it capable of charging and discharging more quickly.
Lithium nickel manganese oxide consists of layers of metal (nickel and
manganese) separated from lithium layers by oxygen. The major problem with
the compound was that the crystalline structure was too "disordered,"
meaning that the nickel and lithium were drawn to each other, interfering
with the flow of lithium ions and slowing down the charging rate. Lithium
ions carry the battery’s charge, so to maximize the speed at which the
battery can charge and discharge, the researchers designed and synthesized
a material with a very ordered crystalline structure, allowing lithium
ions to freely flow between the metal layers.
A battery made from the new material can charge or discharge in about
10 minutes -- about 10 times faster than the unmodified lithium nickel
manganese oxide. That brings it much closer to the timeframe needed for
hybrid car batteries, Ceder said.
Before the material can be used commercially, the manufacturing process
needs to be made less expensive, and a few other modifications will likely
be necessary, Ceder said.
On the Web (links open in a new window):
Massachusetts Institute of Technology
