Researchers at the University of Colorado have used the Advanced Photon Source at Argonne National Laboratory, one of the most powerful X-ray light sources in the world, to find the cause of the premature aging of lithium-ion batteries.
Michael Toney and his team discovered that hydrogen molecules from the battery’s electrolyte, which separates the two electrodes, migrate to the cathode during operation and occupy places where lithium ions would normally bind. As a result, they have less and less space over the years, reducing the battery’s capacity.
In practical terms, this means that the range of electric cars equipped with them is decreasing more and more and mobile phones have to be connected to the charger more and more often. The discovery does not mean that a solution is in sight. But the way has been shown, says Toney. Engineers can now look specifically for ways to prevent the process.
Wrong paths in replacing cobalt
One option is to coat the cathode in a way that repels hydrogen molecules but allows lithium atoms to pass through, or to use a different electrolyte that does not release hydrogen. “Now that we understand what causes battery degradation, we can inform the battery chemistry community about what needs to be improved when developing batteries,” says Toney.
For years, researchers and industry have been looking for ways to slow down the loss of capacity in batteries. They are concentrating primarily on using new cathode materials. The aim was not only to replace cobalt, which is controversial due to the humanitarian problems associated with mining, but also to improve the service life. But so far they have achieved the opposite: the capacity has decreased more quickly than when using cobalt-containing cathodes.
Source: www.com-magazin.de
