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Study finds rapid charging and draining doesn’t damage lithium-ion electrode as much as thought

14 September 2014

X-ray microscope snapshot of nanoparticles in a battery midway through charging. Particles range from fully charged (green) to intermediate charge (orange/yellow) to drained of charge (red) The scalebar equals 500 nm. (SLAC National Accelerator Laboratory) Click to enlarge.

A new study has found that rapid-charging a lithium-ion battery and using it to do high-power, rapidly draining work may not be as damaging as researchers had thought, and that the benefits of slow draining and charging may have been overestimated. The study, led by 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, is published in Nature Materials.

The results challenge the prevailing view that “supercharging” batteries is always harder on battery electrodes than charging at slower rates. The results also suggest that scientists may be able to modify electrodes or change the way batteries are charged to promote more uniform charging and discharging and extend battery life.

The fine detail of what happens in an electrode during charging and discharging is just one of many factors that determine battery life, but it’s one that, until this study, was not adequately understood. We have found a new way to think about battery degradation.

—William Chueh of SIMES, senior author

The results, Chueh said, can be directly applied to many oxide and graphite electrodes used in today’s commercial lithium ion batteries and in about half of those under development.

An important source of battery wear and tear is the swelling and shrinking of the negative and positive electrodes as they absorb and release ions from the electrolyte during charging and discharging.

Researcher Yiyang Li describes the results of his team’s experiments watching how batteries charge and drain.

Yiyang Li

For this study scientists looked at a lithium iron phosphate cathode material. If most or all of the nanoparticles in the material actively participate in charging and discharging, they’ll absorb and release ions more gently and uniformly. However, if only a small percentage of particles take in the ions, they’re more likely to crack and get ruined, degrading the battery’s performance.

Previous studies produced conflicting views of how the nanoparticles in the cathode material behaved. To probe further, researchers made small coin cell batteries, charged them with different levels of current for various periods of time, quickly took them apart and rinsed the components to stop the charge/discharge process. Then they cut the electrode into extremely thin slices and took them to Berkeley Lab for examination with intense X-rays from the Advanced Light Source synchrotron, a DOE Office of Science User Facility.

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.

—Yiyang Li, lead author

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.

Two simulations show the differences between a battery being drained at a slower rate, over a full hour, versus a faster rate, only six minutes (a tenth of an hour). In both cases battery particles go from being fully charged (green) to fully drained (red), but there are significant differences in the patterns of discharge based on the rate. Source: SLAC. Click to enlarge.

(Click here to launch in new window if the video doesn’t play embedded within this post on a mobile device.)

The next step, Li said, is to run the battery electrodes through hundreds to thousands of cycles to mimic real-world performance. The scientists also hope to take snapshots of the battery while it’s charging and discharging, rather than stopping the process and taking it apart.

This should yield a more realistic view, and can be done at synchrotrons such as ALS or SLAC’s Stanford Synchrotron Radiation Lightsource, also a DOE Office of Science User Facility. Li said the group has also been working with industry to see how these findings might apply in the transportation and consumer electronics sectors.

Research funding came from the Samsung Advanced Institute of Technology Global Research Outreach Program; the School of Engineering and Precourt Institute for Energy at Stanford; the Samsung-MIT Program for Materials Design in Energy Applications; and the US Department of Energy; and the National Science Foundation.


  • Yiyang Li, Farid El Gabaly, Todd R. Ferguson, Raymond B. Smith, Norman C. Bartelt, Joshua D. Sugar, Kyle R. Fenton, Daniel A. Cogswell, A. L. David Kilcoyne, Tolek Tyliszczak, Martin Z. Bazant & William C. Chueh (2014) “Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes” Nature Materials doi: 10.1038/NMAT4084

September 14, 2014 in Batteries | Permalink | Comments (7) | TrackBack (0)


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M. Musk from Tesla was correct all this time. Ultra quick charges may not damage lithium batteries as much as many believed.

Secondly, futurs electrodes will be tweaked to further inprove quick charg/discharge capabilities.

200+ KW chargers will become common place by 2020 or so.

This is also great for HEV's having a small battery pack that is subjected to frequent high rates of charging and discharging.

For BEV's, fast charging will reduce efficiency and increase the risk of fire or explosion, so should do this only when really necessary during long trips, not regularly.

Gotta tell ya what I like about all this is to see the various groups sharing the information, using each others research devices and test processes and working together for a common good.

It will be interesting to compare the results for various other chemistries. LiFePO4 is but one flavor of jelly bean in the jar.

Roger, you may be fascinated to watch the following video presentation by Dr Jeff Dahn of Dalhousie University in Halifax, Nova Scotia.

He concludes that slow charging is more harmful to EV batteries than fast charging, and has very good supporting evidence:

Good video. Thanks. I posted a link to it from Tesla Motors site. I can't make them smarter over there so at least I can assist them to be informed !
The video runs for more than an hour. Here's what I took from it.

The video begins with Prof Dahn of Dalhousie U. discussing battery longevity issues brought on by charging.

It is known that charging cells when cold is beneficial to slow the formation of a coating on the surface of the cathode material. Consequently a useful strategy is to ensure a limit to the time that the cell is heated by the charging process. It follows that speeding up the process at a rate of around 1.5C gets the process over quickly so that the cell can be cooled immediately and so curtail the time window for the coating to form.

Throughout this video, made last year, Prof Jeff Dahn makes several references concerning Tesla Motors. In particular mention is made that one of the original researchers, Aaron Smith, had moved over to Tesla in March of 2012.
At Dalhousie, Smith was involved with the assembly of test equipment to measure the exothermic generation, at the tens of nanowatt level, during the parasitic formation as separate from other heat sources within the cell.

Prof Dahn goes on to say that apparently discerning the difference between microwatts and nanowatts is key in predicting the coulomb efficiency drop off. Of course when the cell cathode is totally plastered -so to speak - and drop off in performance now becomes more rapid, well that particular condition remains harder to quantify. However the enhanced measuring techniques mean that you don't have to put a cell through thousands of cycles to determine when its useful end of life (80%) is likely to be.

Further insight into cell design was given that it is not just one compound that improves longevity but the synergism of several additives and that is making scientific progress difficult. It appears that a twentyfold increase in cycle life can be made by a mere 1% addition of one new substance providing other electrolyte additives are present in the right quantity. On the other hand if you're not optimising the additives but think that you can just try to figure out the mechanism of why they work the way they do then you're CRAZY ! That's with the equipment now being used at the current SOTA, I am assuming.

Bottom line. As a first choice it is actually more preferable to be using Superchargers than even L2 chargers but only if the cells are cold.

Racing between superchargers thus needing to visit more supercharger stations on your route - assuming circumstances permit - is not so much a good idea, unless the Thermal Management System has been able to precool the pack.

Charging from 110Vac won't introduce much heating, of course, but it might be better to be doing it when the battery is known to be cold.
I guess the use of these techniques requires a name analogous to hypermiling.

I doubt that they discover something, it look too limited a study. If you live in an apartment and don't have a dedicated spot to recharge then you must fast recharge at a nearby fast charger and today in autobloggreen I just learn that blink double his fee for charging and that cost per mile are the same as someone having a 40 mpg car. All in all bev are unsustainable because half the drivers don't have a dedicated spot to recharge and a spread broad fast charging infrastructure is impossible to implement. Also fast recharge get you to 80% capacity only.

There is no norm for charging and fast recharging and bev commercialization is a flop because of car manufacturers, goverments, scientists, journalists, bloggers, electric utilities, society of automotive engineers, battery makers, investors.

here is the link for the chargers fees hike

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