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lithium iron phosphate, the parts of the material that contained
lithium would separate from those that didn't as the lithium ions
moved in and out of an electrode. That changed the crystalline
structure of the material, and its performance deteriorated. But,
Chiang discovered, when the particles of lithium iron phosphate
are small enough---and the electrode has been modified, or "doped,"
through the addition of other metals---the material's crystalline
structure changes far less. As a result, the lithium ions can move in
and out faster, without degrading the material. Altogether, Chiang
found that the modified material charged and discharged faster
than ordinary lithium iron phosphate, and it lasted longer, too.
Extraordinary though the new battery material seemed to be,
Chiang realized immediately that it wasn't ideal for portable elec-
tronics. There didn't seem to be a ready market for light, compact
batteries that delivered large bursts of power. Hybrid vehicles, a
natural fit, were only beginning to appear on the market. What
Chiang didn't know was that a major power-tool company was
working quietly on a new generation of cordless tools, and it was
having trouble finding a battery that would meet its needs.
In 2003, representatives of Black and Decker met with Fulop and
A123's CEO, Dave Vieau, and told them that they wanted to make
cordless power tools that would perform better than tools plugged
in to the wall. A123's material seemed like a perfect fit. In short
bursts, it can deliver more power than a household circuit. And it
had other features that would be attractive on a construction site.
It could be recharged quickly (to 80 percent of capacity in 12 min-
By the fall, Fulop and Chiang, along with Bart Riley, an engineer
Chiang knew from his previous venture, had cofounded A123 Sys-
tems. The plan was to commercialize one of Chiang's more radical
ideas: materials that, when stirred together, would spontaneously
assemble to form a working battery. The process promised to multi-
ply energy storage capacity while lowering manufacturing costs.
Chiang's big idea turned out to be a hit with investors. By the
end of 2001, a first round of funding had brought in $8.3 million
from various venture capital firms. Motorola and Qualcomm,
intrigued by the prospect of better batteries for portable elec-
tronics, soon added $4 million. But it quickly became clear that a
commercial self-assembling battery was years away from reality.
The technology "was still pretty rudimentary," Chiang says.
In early 2002, however, Chiang made a surprising discovery
that would completely change the company's direction. He had
begun to work with lithium iron phosphate, which is nontoxic,
safe, and inexpensive, unlike the materials used in other lithium-
ion batteries. But it appeared to have some serious drawbacks. It
stores less energy than lithium cobalt oxide, the electrode material
in conventional lithium-ion batteries, so it seemed unsuitable for
use in portable electronics, where energy storage is paramount.
Also, it charges and discharges slowly, ruling out its use in high-
power applications such as hybrid electric vehicles; even for fully
electric cars, which use many more battery cells than hybrids, the
material couldn't deliver enough power.
So Chiang started to modify it by adding trace amounts of met-
als. Soon the material was discharging power at relatively high
rates. In mid-2002, he flew to Monterey, CA, to present his find-
ings at a conference. While he was there, a graduate student back at
MIT continued running tests. By the time Chiang was scheduled
to talk, the material was performing at rates four times those he
had come to announce. "At that point, we knew we had something
special," he says.
Eventually, Chiang would demonstrate that the material
could deliver bursts of electricity at 10 times the rate of those
used in conventional lithium-ion batteries. After studying the
high-performing material in detail, he determined that it owed
its power both to the size of the particles he'd used (less than 100
nanometers) and to the addition of the extra metals. The com-
bination of those factors, he says, causes a fundamental di er-
ence in the way the atoms that make up the material rearrange
themselves when they receive and release a charge.
In all lithium-ion batteries, electricity is generated when lith-
ium ions shuttle between two electrodes while electrons travel
through an external circuit. In Chiang's early experiments with
PAC K E D U P A123 s battery cells (right) have been
integrated into a T-shaped pack engineered by the
German firm Continental (above). GM is testing the pack
under simulated driving conditions before bolting it into
an electric-vehicle prototype.
See how an electric car recharges itself, and hear how the origi-
nator of A123 s technology is going to change the automotive
COURTESY OF GENERAL MOTORS
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