Batteries are a critical part of our everyday lives. From phones to laptops to cars to grid energy storage—batteries are essential to many devices. Lithium ion batteries have taken the lead in battery technology, with lithium iron phosphate batteries (LFP) performing particularly well. While it was known that LFP batteries could charge quickly and withstand many factors, the reasons for this were unknown until know.
A team of researchers from the Paul Scherrer Institute and Toyota Central R&D Labs has discovered why LFP batteries can be recharged so rapidly. The team is comprised of ECS member Tsuyoshi Sasaki, past members Michael Hess and Petr Novak, and Journal of The Electrochemical Society (JES) published author Claire Villevieille.
(PS: Check out their past paper, “Surface/Interface Study on Full xLi2MnO3·(1 − x)LiMO2 (M = Ni, Mn, Co)/Graphite Cells.”)
This from Paul Scherrer Institute:
The reason: the step-like concentration gradient gives way to a gentle, ramp-like progression of the lithium concentration. This is because, at higher voltages, the lithium ions involved in the charging process are distributed across the volume of the electrode particles for brief moments as opposed to being herded together in a thin layer boundary. As a result, the lithium can be set in motion more easily during charging, without the need for more energy to be added to negotiate the layer boundary.
Essentially, a slow charge creates a type of step that the lithium ions have to climb. While the lithium ions are quick to line up, they have to wait their turn to climb the step. However, the rapid charge allows the lithium ions to move quickly along a type of ramp, allowing the atoms to all move together.
The measurement technique developed by the scientists has allowed them to more accurately examine the charge process and will allow continuing research to improve the lithium ion battery.
“Using our novel measuring technique, we confirmed some theories and debunked others that endeavor to explain the rapid chargeability of LFP batteries,” said Novak. “Our results not only enable us to understand the LFP battery better and help refine it; the measuring method we developed will also enable us to study materials that are used in other batteries that can be charged just as quickly. Therefore, other battery types also stand to benefit.”