Editor:
Kevin
Bullis
From: NBC
news
Date: Sep, 2012
There are plenty of reasons why electric cars aren’t
catching on, but one problem is certain: the batteries cost far too
much.
For electric vehicles and plug-in hybrids to compete with
gas-powered cars, battery prices need to drop by between 50 and 80 percent,
according to recent estimates by the U.S. Department of Energy. Getting there
might require inventing entirely new kinds of batteries, but
there’s also a strong case that improvements to the lithium-ion
batteries that power the current generation of electric vehicles may be
enough.
The United States could have the capacity by 2015 to produce
enough battery packs for 500,000 cars. But this year, due to high prices,
plug-in vehicle sales won’t even reach a tenth of that in the
United States. As a result, advanced battery makers in the United States have
struggled. A123 Systems went bankrupt. Dow said its battery joint venture Dow
Kokam had dropped markedly. And an LG Chem factory meant to supply batteries
for the Chevrolet Volt has been built, but the factory is sitting idle,
waiting for demand to pick up.
Electric vehicles cost less to operate than gas-powered ones, but
that economic advantage largely disappears in the face of expensive
batteries. The battery pack for the Chevrolet Volt costs about $8,000. The
larger battery in the Nissan Leaf costs about $12,000.
The cost for the Leaf battery could drop to under $4,000 by 2025,
according to a recent study by McKinsey, just by increasing the scale of
battery production, forcing down component costs through competition, and
approximately doubling the energy density of batteries, which reduces
materials costs.
One startup, Envia Systems, has already built prototype
lithium-ion battery cells that store about twice that of the best conventional
lithium-ion batteries and can be recharged hundreds of times (see
“A Big Jump in Battery Capacity” and “Should
the Government Support Applied Research?”). And crucially,
it’s similar enough to conventional lithium-ion batteries that it
can be made on existing manufacturing equipment. The technology still needs
work, and could take several years to start appearing in cars, the company
says.
Jeff Dahn, a lithium-ion battery researcher at Dalhousie
University, says cars like the Leaf and Volt use a special type of flat
lithium-ion cell that is made with recently developed equipment that is still
relatively slow. More conventional cylindrical lithium-ion cells cost roughly
half as much to make because they use much faster equipment and are made at a
larger scale. Dahn also notes that many of the components, such as a plastic
film that separates electrodes in a battery, are overpriced. “You
can’t tell me separator cost can’t come
down.”
Not everyone agrees that lithium-ion batteries can reach the low
costs needed for electric vehicles to compete with gas-powered ones (see
“A123’s Technology Just Wasn’t Good
Enough”). Toyota, for one, is investigating more dramatic changes
in battery design. One type it’s developing replaces the liquid
electrolyte in a conventional lithium-ion battery with a solid material, something
that allows for a number of changes in the battery design that could shrink
the system and lower the cost. These solid-state batteries and other
technologies could cut the size of a battery pack by 80 percent, according to
Toyota. Sakti3, a startup with close ties to GM, is also developing
solid-state batteries, and recently started shipping prototype batteries to
potential customers for testing, says CEO Ann Marie Sastry (see
“Solid-State Batteries”).
24M, an early-stage startup based in Cambridge, Massachusetts, is
taking a different approach—rather than an all-solid battery, the
company is developing a cross between a battery and a fuel cell in which the
battery electrodes are a sludgy liquid that can be pumped around. The energy
storage material could be stored in inexpensive tanks, and then pumped into a
small device to generate power (see “A Car Battery at Half the
Price”).
Despite the novel designs, solid-state batteries and
24M’s technology still operate with a familiar lithium-ion
chemistry, which could make them less risky to commercialize than more
radical approaches that move beyond the lithium-ion chemistry. But alternatives
to lithium ion batteries could be worth their added risk, since
they have theoretical energy densities several times that of
today’s electric car batteries.
The list is long, including lithium-sulfur, lithium-air, zinc-air,
and magnesium-ion. But each seems to have its own unique problems. For
example, lithium-air batteries, which could store 10 times more energy than
conventional lithium-ion batteries (approaching the energy density of gasoline),
use lithium metal, which can be very dangerous, and they can’t be
recharged very many times.
Even if the issues for the new technologies can be solved in the
lab, it could take decades to develop the manufacturing needed to reliably
make the batteries in the large numbers needed to power cars. The process of
solving these challenges will give conventional lithium-ion battery
technologies a long time to improve.