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The original textWill charging electric cars ever be as fast as pumping gas?
Slow charging times are holding back potential EV customers, but emerging science
says a fast-charging battery is possible.
BYMADELEINE STONE PUBLISHED JUNE 9, 2021
• 9 MIN READ
Electric vehicles are gaining popularity fast, but some prospective buyers remain
hesitant. One big reason is that charging EVs is slow. While drivers today are
accustomed to filling their gas tank in less than five minutes, EVs, depending on the size
and specifications of the battery, typically take at least 30 minutes to get 80 percent
charged at the fastest charging stations out there.
In five to 10 years, though, far faster charging might be possible. Companies are
developing new lithium-ion battery materials, as well as new “solid state” batteries,
which are more stable at faster charging speeds. They could place recharge rates of 20
minute or less within reach.
Meanwhile, a team of scientists recently designed a lithium battery prototype that,
under laboratory conditions, can recharge more than 50 percent of its capacity in just
three minutes—and do so thousands of times without significantly degrading. This, the
researchers say, could pave a path toward batteries that can recharge fully in as little as
10 minutes.
However, there are still science and engineering challenges to overcome before ultra
fast-charging EV batteries are both technically feasible and affordable. And some
experts question whether EVs that can be charged so quickly are really the future we
want—at least with the electric grid we have now.
Charging up
The batteries inside today’s EVs are composed of thousands of lithium-ion cells with the
ability to store and release energy thousands of times. Each of those cells consists of
two electrodes—a metal cathode and a graphite anode—separated by a liquid
electrolyte. While the battery is charging, lithium ions flow through the liquid from the
cathode to the anode, filling up spaces between the graphite layers like wooden blocks
fitting into a Jenga tower.
The speed at which lithium ions move from the cathode into the anode dictates how
quickly the battery charges. But just as placing blocks in a Jenga tower hastily can
cause the structure to become unstable, if lithium is forced into the anode too fast,
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, problems start to arise.
At high charging speeds lithium batteries can overheat, causing them to degrade over
time. More problematically, lithium can start to build up on the surface of the anode
instead of entering it, a phenomenon known as lithium plating. Not only can that
drastically reduce the battery’s capacity, the lithium deposits eventually form filament-
like structures known as dendrites. Once they start forming, those dendrites can grow
across the electrolyte, touch the cathode and create a short circuit, causing the battery
to catch fire or explode.
“Obviously that’s not particularly good from a safety point of view,” says Peter Slater, a
professor of materials chemistry at the University of Birmingham in the U.K.
Because of the problems with fast charging, all EV batteries have built-in charging
speed limits, set by the car’s on-board charge ports. A 350-kilowatt fast charging
station—the most powerful public charger available in the U.S. today—might, in theory,
be able to charge an Audi E-tron SUV’s 95 kilowatt-hour battery in about 16 minutes.
But the battery itself can only accept about 150 kilowatts of power at most, placing its
actual charging speed limit closer to 40 minutes.
Exactly how fast a battery will recharge in the real world depends not only on the
charger or how many kilowatts of power the battery was designed to accept, but the
battery’s size, how charged it is, and even the weather. Still, state-of-the art fast
charging stations can often get an EV battery 80 percent full, potentially adding
hundreds of miles of range, in about 30 minutes. (Once a battery is 80 percent full, the
charging speed slows down to prevent the battery from being damaged.) Tesla owners
can visit a supercharging station that will add up to 200 miles of range in 15 minutes.
An ultra-fast charging future?
While adding 200 miles of range in 15 minutes is fast, it’s a far cry from gassing up for a
road trip in five minutes flat. Those hoping for an EV charging experience like that might
want to hold out for the next generation of battery technologies.
One way to make a lithium-ion battery that can safely charge even more quickly is to
use alternative anode materials. For instance, the U.K.-based startup Echion
technologies has developed a niobium anode that doesn’t promote lithium plating or
dendrite formation. Batteries made with this material can be charged “as fast as you
want,” says CEO Jean De La Verpilliere. His prototype EV battery cells can be charged
in six minutes “without impacting the safety or life of the battery,” he says.
However, that quick charge comes with a price: Niobium anodes store less energy per
unit mass than conventional graphite ones. Because EV makers tend to prioritize
energy-dense batteries (which can be driven longer on a single charge) over ultra-fast
charging ones, Echion is currently targeting other markets for its batteries, like grid
storage and power tools. Eventually, De La Verpilliere envisions that a version of these
batteries might be used in vehicle fleets where any downtime to recharge costs the
company money.
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