More encouraging news--this overview and the one
from IEEE
<http://www.calcars.org/calcars-news/638.html> are both good introductions.

Powering GM's Electric Vehicles
Recent advances in battery chemistry and systems
design could lead to working prototypes by year's end.
Technology Review/Published by MIT Thursday, January 11, 2007
By Kevin Bullis
<http://www.technologyreview.com/Energy/18054/>
CAPTION: A123 Systems has designed a new
automotive-grade battery that may make General
Motors’ plug-in hybrids possible.

General Motors (GM) recently announced that it is
developing two types of plug-in hybrid vehicles,
cars designed to run exclusively or almost
exclusively on electricity for daily commutes.
(See "GM's New Electric Vehicle" and "GM's
Plug-In Hybrid.") But the announcements came with
this caveat: the battery technology isn't ready,
and production will have to wait. In reality, the
battery technology is actually quite close to being ready.

Indeed, GM's vehicle chief engineer, Nick
Zelenski, says that individual batteries are
already good enough. "We've got enough data at
the cell level to feel that the technology is
there," he says. What remains to be done is
packaging the cells into large battery packs and
testing them in actual vehicles. This will be a
challenge, Zelenski says, since there is a big
difference between using "a single cell and
multiplying them all together to get the energy
levels that we need for this type of vehicle."
But according to development contracts GM
recently signed with two groups of companies,
such battery packs will be ready for testing in
vehicles by the end of this year.

Making batteries for vehicles, especially plug-in
hybrids, is very challenging. For accelerating
and climbing hills, the battery pack has to
deliver enough power to supply the electricity
demand of several houses at once. The energy
storage capacity required to give a vehicle a
40-mile range would be enough to power a laptop
in continuous use for weeks. Yet the space on
board for such a battery pack is limited. "What
we need is a very reliable and long-lived battery
that has also got quite high energy density so we
can find a place for it in the car," says Peter
Savagian, director of hybrid power-train systems at GM.

Developers also need to make packs that can
survive extremes in temperature and constant
vibrations on the road, and still last the life
of a vehicle. And they have to make the batteries
safe. Last year millions of laptops were recalled
because of the danger of their batteries bursting
into flame. A plug-in hybrid would have the
equivalent of hundreds of laptop battery packs bundled together.

Remarkably, at the level of individual cells,
many of these problems have already been
addressed. Lithium-ion batteries have much higher
capacity than the lead acid batteries used in
electric cars in the past, and even more than the
nickel-metal hydride used in hybrids today.
According to GM, its new Chevrolet Volt concept
vehicle stores the same amount of energy as the
company's EV-1 electric vehicle, but in just
one-third the area. And while lead acid battery
packs have to be replaced every couple of years,
new lithium-ion batteries seem from lab tests to
be able to last 10 years or more.

New lithium-ion batteries are also safer and less
expensive than those in a laptop. One of the
companies under contract with GM to develop
battery packs is A123 Systems, based in
Watertown, MA. It has developed a nanostructured
iron phosphate­-­based electrode that is much
safer than the cobalt-oxide laptop batteries that
were recalled last year. For example, while a
cobalt-oxide battery will burst into flame if
punctured by a nail, the A123 battery merely
releases innocuous wisps of steam. (See "Safer
Lithium-Ion Batteries.") A123 is already
producing millions of its batteries for use in
professional power tools, and now it has
developed a new, larger cell designed to be more
rugged and hold more energy. The company has also
modified the electrolyte to make the battery able
to operate very well at -20 ?F or temperatures up
to 140 ?F. As a result, "the car can operate in
Scandinavia, in Patagonia, or in the summer in
the middle of a tropical city," says Ric Fulop,
cofounder and vice president of business development at A123 Systems.

At this point, cost may still be an issue. But
that will change as more of the cells get made.
"At the end of the day, it's a scale game," says
Alan Mumby, CEO of a joint venture between
Johnson Controls, in Milwaukee, WI, and Saft, in
Paris, France. The venture has been awarded one
of the two contracts for developing battery packs for GM .
Overall, "the fundamental tool kit--the weight,
volumetric efficiency, the demonstration of life
in a lab basis, and safety through extensive
testing--have all been demonstrated," says David
Vieau, president and CEO of A123 Systems. "So
this is not a pie in the sky. However, the actual
execution of all functionality in cells in actual vehicles hasn't been done."

Although integrating the batteries into large
packs is a challenge, in fact it has been done
before. According to Scott Lindholm, vice
president of systems engineering at Cobasys,
based in Orion, MI, which is teaming with A123
Systems on the GM contract to develop battery
packs, many of the problems involved in making
lithium-ion battery packs are similar to those
the company has already solved for the
nickel-metal hydride packs it already produces
for GM hybrids. What's more, several companies
have already made large lithium-ion battery packs
for vehicles. For example, Hymotion, based in
Ontario, has used A123's power-tool batteries to
make kits for converting the Toyota Prius into a
plug-in hybrid. Indeed, its design is one of the
contenders for converting hundreds of New York
State's government-owned hybrids into plug-in
hybrids. These packs are smaller than that used
in GM's Volt concept vehicle, but companies such
as Tesla Motors have already successfully
engineered lithium-ion packs that are a few times larger than GM's pack.

The question is whether such packs can be
engineered to have the life, safety, and cost
that GM wants. As it is, these battery packs can
cost tens of thousands of dollars, placing them
out of the range of most consumers. But part of
the cost has to do with scale, and that should
change if GM puts the vehicle into production.
The price is also coming down as the batteries
are used in other applications, such as power tools.

In all, it seems as though battery technology is
falling into place, just as demand for more
fuel-efficient cars is rising. "It's really
exciting for us to be in this business," says
Fulop. "The timing ended up quite nice. We
developed these products, and the plug-in-hybrid thing is really happening."

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Felix Kramer fkramer@...
Founder California Cars Initiative
http://www.calcars.org
http://www.calcars.org/news-archive.html
http://www.hybridcars.com/blogs/power
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