This could be a big deal…
To quote Blade Runner: “The light that burns twice as bright burns half as long.” That’s usually true, but it might not be quite the case with lithium-ion batteries, or at least, not as much as we thought. A new study published in Nature Materials shows that rapid charging and draining of li-ion batteries is probably not as damaging as previously thought, and that the benefits of taking it slow may also be overestimated.
Researchers from Stanford University and the Stanford Institute for Materials & Energy Sciences (SIMES) at the Department of Energy’s SLAC National Accelerator Laboratory, with colleagues from Sandia National Laboratories, Samsung Advanced Institute of Technology America and Lawrence Berkeley National Laboratory (a lot of great labs!), made small coin cell batteries and charged them with varying amounts of current and for varying periods of time. They then stopped the process and rapidly sliced the batteries’ electrodes into very thin slices to be examined with powerful x-ray instruments.
“We were able to look at thousands of electrode nanoparticles at a time and get snapshots of them at different stages during charging and discharging. This study is the first to do that comprehensively, under many charging and discharging conditions,” said Yiyang Li, the lead author of the study.
Analyzing the data using a model developed at MIT, the researchers discovered that only a small percentage of nanoparticles absorbed and released ions during charging, even when it was done very rapidly. However, when the discharge rate increased above a certain threshold, more and more particles started to absorb ions simultaneously, switching to a more uniform and less damaging mode. This suggests that scientists may be able to tweak the electrode material or the process to get faster rates of charging and discharging while maintaining long battery life. (source)
Of course, this is only a lab result on one kind of battery, but it’s still very encouraging to learn that things might be better than we thought (that’s always more fun than to discover that things are worse than we suspected).
So far it doesn’t look like battery swapping is going to be very mainstream, despite Tesla building the option into its EVs, so fast-charging is going to be very important for long-range travel. Most of the time, electric vehicles will be charged overnight and won’t need any topping off, but on those occasions when you want to travel farther than a single charge can take you, having batteries that can handle a lot of power over a short period of time without sustaining damage will be very important.