Researchers at Ohio State University discovered that in lithium-ion batteries, lithium-ions accumulate inside a sheet of copper known as the current collector. Lithium-ions should not permanently accumulate on the current collector like this, as they are necessary for battery function, therefore this decreases battery performance, as there will be less lithium-ions available.
This is why discoveries like this are often accidental, because they didn’t think that happened, so they didn’t look for it: “We didn’t set out to find lithium in the current collector, so you could say we accidentally discovered it, and how it got there is a bit of a mystery. As far as we know, nobody has ever expected active lithium to migrate inside the current collector,” according to Bharat Bhushan.
Shrikant Nagpure, who is now a postdoctoral researcher at Ohio State University, conducted this research as part of his doctoral degree.
He collaborated with the university’s Center for Automotive Research and examined worn batteries to discover this with the help of Gregory Downing, a chemist at the NIST (National Institute of Standards and Technology) that happens to be an expert at impurity analysis using NDP (Neutron Depth Profiling).
In this case, the impurity is lithium-ions. The test showed that there was one 1 lithium atom for every 1250 copper atoms in the copper collector. While that is a very small ratio, it is enough to affect performance.
This may be due to the fact that lithium-ion batteries operate using small amounts of lithium. So little that lithium comprises 1.5% to 3% of a li-ion battery’s weight.
While this isn’t a technological advancement per-se, it is an important discovery because scientists can start working on a solution that leads to longer-lasting batteries.
Source: Autoblog Green
Photo Credit: Autoblog Green