 An electronic microscope image of the rod-like nanoparticles formed by the microwave production method. They perform extremely well in low discharge scenarios, but are being tweaked after disappointing performance in rapid discharge scenarios. (Source: Arumugam Manthiram, University of Texas at Austin )
Could an affordable electronic car be in the future?
Lithium-ion batteries are in high demand, seeing strong
growth in the consumer electronics, power tools, and automotive industry.
Lithium-ion batteries are prized for their outstanding energy-to-weight ratios,
their lack of memory effect, and their slower charge loss rate than other
battery technologies.
The technology is particularly critical to the budding electric car
business. With such companies
as Dyson, GM, and Lightning
Car Company using the batteries in their upcoming commercial releases the
future of the electric car in the short term is riding on lithium-ion
technology.
Unfortunately, the costs of lithium-ion batteries are currently quite
high. An analyst estimated that the much-anticipated
Chevy Volt's battery pack would cost nearly
$10,000; about a fourth of the total projected cost. The pressing
demand from a variety of industries has fueled lithium-ion prices to rise even
higher.
Fortunately relief is in sight, thanks to a processing breakthrough from University
of Texas at Austin. The researchers found a way to possibly transform the
long and complicated baking process involved in one of the more common
lithium-ion battery materials into a quick and
easy process.
Originally, most lithium-ion batteries used lithium cobalt oxide. Most of
the computer industry still relies on this material; however, the automotive
industry has turned to lithium iron phosphate, which is considered more
attractive as iron is cheaper than cobalt. It is also safer
than the more fire-prone lithium cobalt oxide, and is capable of being
crafted to release charge faster. A downside is it stores slightly less
charge.
Companies have invested big in developing and bringing lithium iron phosphate
to the market. A123 Systems, the Watertown, MA startup that is
manufacturing the Chevy Volt's battery, has already commercially offered
lithium iron phosphate batteries for power tools. It has managed to raise
$148M USD in investment capital to help fund its efforts.
With current technology, the biggest downside to the lithium iron phosphate is
the manufacturing. Currently, the process takes hours of baking at
temperatures in excess of 700 °C. The extra manpower and effort required
due to this has meant that Lithium iron phosphate batteries, which should from
a materials perspective be much cheaper than lithium cobalt oxide, are actually
more expensive than their competitor.
Led by Professor Arumugam Manthiram, a U of T professor of materials
engineering, the researchers at U of T examined how a microwave could be used
to speed the cooking process. The results were dramatic.
The team first mixed conventional materials -- lithium hydroxide, iron acetate,
and phosphoric acid -- in a solvent. They then popped the mixture in the
microwave for about five minutes, which heated the mix to about 300 °C.
The process yielded high performing rod shaped nanoparticles of lithium iron
phosphate. The best nanoparticles were found to be approximately 100 nm
long and just 25 nm wide. The small size allows the ion exchange to be
performed more easily. The finished particles were then covered with an
electrically conductive polymer doped with sulfonic acid to improve
performance.
The new particles performed extremely well in low-discharge scenarios.
The material achieved a capacity of 166 milliamp hours per gram, amazingly
close to the 170 milliamp hours per gram theoretical capacity. High
discharge scenarios were not so friendly to the new material, but Professor
Manthiram says that will be fixable. He says new versions have already
shown improvement in this metric.
It is unclear exactly how much will be saved using the new method. With
the short time higher production should be possible, and the lower temperatures
will reduce energy demands, both effects that should help to lower the cost of
production. Some are skeptical, though; whether the material will save
much at all. Stanley Whittingham a professor of chemistry, materials
science, and engineering at the State University of New York, at Binghamton
warns that the savings may be offset by the polymer cost and the cost of the
changes necessary to the production.
Professor Manthiram is also exploring other lithium ion materials and has
developed two key improvements on other materials. He is working with an
Austin, TX based startup, ActaCell to commercialize his tech. The startup
has licensed some of his technology with the help of the $5.58M USD in startup
funds in has raised, but declined to specify which technologies or whether the
new lithium iron phosphate production technology had been licensed yet.
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