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RESEARCH
May 19, 2009
Sulfur promises super batteries
Melt sulfur into nanoscale holes in
porous carbon and you can dramatically increase lithium-ion battery
capacity.
Lithium-ion battery electrodes made of carbon and sulfur have
a theoretical capacity five times greater than the theoretical limit
for today's lithium-ion electrode materials, but sulfur tends to leak
from the electrodes.
An electrode made by melting sulfur into porous carbon holds
onto its sulfur. The porous carbon consists of carbon nanorods separated
by 3-nanometer channels containing carbon fibers that help hold the
structure together. The fibers keep most of the sulfur from leaking
out and also provide electrical contact to more of the sulfur. A polymer
coating on the outside surface of the carbon also helps hold in the
sulfur.
The plastic-coated carbon-sulfur electrode has a stable discharge
capacity of 1,100 milliamp hours per gram, which is about six times
that of today's best commercial lithium-ion batteries.
Recent research with crystalline silicon electrodes shows
the potential for even higher storage capacities. Crystalline silicon
is more expensive than porous carbon and sulfur.
Carbon-sulfur electrodes could be used in electric vehicles
with extended ranges and storage systems for renewable energy sources
like solar cells and wind turbines.
Research paper:
A
highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur
batteries
Nature Materials, published online May 17, 2009
Researchers' contact:
Linda F. Nazar
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