Editor: John
Roach
The days of gas-guzzling cars may come to an end before we run out
of oil if technologies such as 500-mile-per-charge lithium-air batteries
become a real and affordable option. A company that customizes carbons at the
molecular level believes it can help us get there.
Along the way, the same process the company employs to manufacture
carbons for prototype lithium-air batteries is being used to improve the
efficiency of batteries in gasoline and hybrid-electric vehicles, making a
dent in carbon emissions.
For
example, Seattle-based EnerG2 is
developing carbons that improve the life cycle of lead-acid
batteries at the heart of so-calledÂ
“start-stop ” hybrid vehicles. These cars work like
gas-fueled golf carts: punch the accelerator and the engine starts; come to a
full stop and the engine idles off.
“That gives you about an 8 to 12 percent boost in fuel
economy,” Rick Luebbe, EnerG2 co-founder and CEO, told me in an
interview at the company’s headquarters.
The company manufactures a highly pure carbon with a precisely
tailored pore structure that’s an additive to lead acid battery
chemistry. This has led to a ten-fold improvement in the life cycle of the
batteries, a key step to bringing down the cost of the technology and
accelerating its adoption.
The carbon adds about $3 to $7 to the cost of a battery, Luebbe
noted, but with a 10 percent boost in fuel economy it will pay for itself
quickly. He expects the start-stop technology to be in most new cars within a
few years.
“And it looks like our carbon is going to be one of the
key enablers to make that work in a more cost-effective way,” he
said.
Custom Carbons
Carbon
comes in many forms — from diamonds to graphite to coal. Each form
is determined by its molecular structure. The technology at the heart of
EnerG2 is a platform that enables the customization of carbon structures at
the molecular level.
“The way those carbons are structured really determines
how good they are in an application,” Luebbe said. “We
then realized that how a carbon is structured is really a reflection of the
molecular structure of the precursor.”
The precursor is the source of the carbon. Coconut shells are the
precursor for the porous carbon electrodes in ultracapacitors, for
example.
“Coconuts didn’t evolve with the intent to be
involved in ultracapacitors, ” Luebbe
noted.
Thinking there had to be a better way, EnerG2 modeled the
ideal structure of a porous carbon for ultracapacitors and then
built a precursor to match it. They make the precursor out of polymer
materials commonly used as binders in the forest products industry for things
such as particle board.
“We address the polymerization reaction with different
catalysts and with different ratios of inputs in order to get that molecular
structure that we want,” Luebbe explained.
This polymer is freeze dried, which removes solvents while
retaining its shape, and then carbonized – cooked under high heat.
“We are left with a pure carbon material that is structured the way
that we want,” he said.
These custom tailored carbons, in turn, lead to ultracapacitors
with a higher energy performance than their coconut-shell-based
cousins.
Current and Future
EnerG2 is currently working with about 60 companies in the
ultracapacitor and lead-acid industries, Luebbe said. In addition, the carbon
pushers are in talks with makers of lithium-ion and lithium-air batteries.
The hurdle with lithium-air batteries is making them actually work
as promised. IBM, which is plowing untold millions on its own lithium-air
technology, recently announced success in the lab but
said much more work is required before any such battery stands a chance in
the real world.
EnerG2 is not working with IBM on its effort, but is collaborating
with “some smaller companies” in the space as well as
major car companies who see the technology as the next big thing, Luebbe
noted.
None of these companies is expected to have a
commercially available lithium-air battery anytime soon.
One of the key hurdles is recharging the batteries, which generate
energy via a chemical reaction that combines oxygen breathed in from the air
and lithium ions, creating lithium peroxide. To recharge the battery, the
lithium peroxide needs to cross a separator that returns the oxygen to the
air.
This recharging process has proven difficult. Luebbe thinks
EnerG2’s technology can tailor carbon pores in such a way that they
“change the reaction kinetics of the
reversibility.”
And this wonky bit of chemistry, enabled by a proprietary
technology, is what gets Luebbe most excited when speaking about the future
prospects of his company, which was founded in 2003.
“If we can make a lithium-air battery work commercially,
then we can obsolesce gasoline as a transportation fuel, ” he
said.