Longer-lasting electric vehicle batteries could be on the horizon following a breakthrough.
Scientists have discovered the reason batteries lose capacity over time.
It is well known that, for example, older mobile phones run out of power more quickly.
But, until now, the common phenomenon was not completely understood.
An international research team led by an engineer at the University of Colorado, Boulder, has uncovered why such batteries degrade over time.
They say the discovery could lead to the development of better batteries, which would allow electric vehicles to run farther and last longer.
According to the findings, it could also advance energy storage technologies, which would accelerate the transition to “clean” energy.
Study leader Professor Michael Toney of the University of Colorado, Boulder, said, “We are helping to advance lithium-ion batteries by figuring out the molecular-level processes involved in their degradation.
“Having a better battery is very important in shifting our energy infrastructure away from fossil fuels to more renewable energy sources.”
Engineers have been working for several years on designing lithium-ion batteries—the most common type of rechargeable battery—without cobalt.
Cobalt is an expensive rare mineral, and its mining process has been linked to environmental and human rights concerns.
In the Democratic Republic of Congo, which supplies more than half of the world’s cobalt, many miners are children.
Researchers have previously tried replacing cobalt in lithium-ion batteries with other elements, such as nickel and magnesium.
But those batteries have even higher rates of “self-discharge” – which is when the battery’s internal chemical reactions reduce stored energy and degrade its capacity over time.
Because they self-discharge, most electric vehicle batteries last seven to ten years before they need to be replaced.
Toney and his team set out to investigate the cause of self-discharge.
He explained that in a typical lithium-ion battery, lithium ions, which carry charges, move from one side of the battery, called the anode, to the other side, called the cathode, through a medium called an electrolyte.
During the process, the flow of the charged ions forms an electric current that powers electronic devices.
Charging the battery reverses the flow of the charged ions and returns them to the anode.
Previously, it was thought batteries self-discharge because not all lithium ions return to the anode when charging, reducing the number of charged ions available to form the current and provide power.
Using the Advanced Photon Source, a powerful X-ray machine at the U.S. Department of Energy’s Argonne National Laboratory in Illinois, the research team found that hydrogen molecules from the battery’s electrolyte would move to cathode and take the spots that lithium ions normally bind to.
As a result, lithium ions have fewer places to bind to on the cathode, weakening the electric current and decreasing the battery’s capacity.
Electric vehicles can currently run for an average of around 200 miles on a single charge.
But Toney says the new study, published in the journal Science, has the potential to increase their range.
He said: “All consumers want cars with a large driving range.
“Some of these low cobalt-containing batteries can potentially provide a higher driving range, but we also need to make sure they don’t fall apart in a short period of time.”
Toney says that reducing cobalt can also reduce costs as well as addressing human rights concerns.
With a better understanding of the self-discharge mechanism, he believes engineers can explore several ways to prevent the process, such as coating the cathode with a special material to block hydrogen molecules or using a different electrolyte.
Toney added: “Now that we understand what is causing batteries to degrade, we can inform the battery chemistry community on what needs to be improved when designing in batteries.”
Produced in association with SWNS Talker
