Scientists announce progress toward better battery to power cars

By Will Dunham
WASHINGTON, Oct 29 (Reuters) - Scientists have created a
battery whose technology in principle could power electric cars
and other energy-hungry devices far better than current
lithium-ion batteries, but it remains years away from commercial
use.
Researchers at the University of Cambridge on Thursday
announced the creation of a laboratory demonstration model of a
lithium-oxygen battery that overcomes many of the barriers that
have held back the development of this technology.
They said the battery boasts very high energy density, is
about 93 percent efficient - better than previous efforts - and
can be recharged more than 2,000 times.
Clare Grey, a Cambridge professor of materials chemistry who
led the research, called it "a step towards a practical battery,
albeit with many hurdles ahead." The researchers said it could
be more than a decade before a practical lithium-oxygen battery
is ready, in part because the battery's ability to charge and
discharge is too low.
In cars, the range for a compact, fully charged battery has
been unable to reach that of a full tank of gasoline in a
regular engine because current lithium-ion batteries do not pack
that kind of power punch.
The lithium-ion rechargeable battery, first introduced in
1991, helped power the portable electronics revolution including
laptops and smartphones as well as powering some vehicles.
Lithium-oxygen batteries, also called lithium-air batteries,
have the potential to deliver the desired power thanks to a high
energy density - a measure of energy stored for a given weight -
that could be 10 times that of lithium-ion batteries and
approach that of gasoline. They also could be a fifth the cost
and a fifth the weight of lithium-ion batteries.
But problems have beset lithium-oxygen batteries that affect
their capacity and lifetime, including troublesome efficiency,
performance, chemical reaction and potential safety issues and
the limitation of needing pure oxygen rather than plain old air.
The Cambridge demonstrator battery employs different
chemistry than previous work on lithium-air batteries, for
example using lithium hydroxide rather than lithium peroxide. It
also uses an electrode made of graphene, a form of carbon. The
result was a more stable and efficient battery.
Grey said it is too early to gauge lithium-oxygen battery
range limits in vehicles.
Intellectual property from the research is owned by
Cambridge Enterprises, the university's commercialization arm,
and has been patented, Grey said.
The research was published in the journal Science.