Million-mile battery unveiled by ground-breaking research

Million-mile battery unveiled by ground-breaking research
Credit: Institute of Physics

Elon Musk promised—and Jeff Dahn delivered. With the publishing of a ground-breaking paper in the Journal of The Electrochemical Society (JES), Dahn announced to the world that Tesla may soon have a battery that makes their robot taxis and long-haul electric trucks viable.

Dahn and his research group are Tesla's battery research partner. Dahn said: "Cells of this type should be able to power an electric vehicle for over one million miles and last at least two decades in grid energy storage."

According to Doron Aurbach, JES batteries and energy storage technical editor: "This comprehensive article is expected to be impactful in the field of batteries and energy storage. It is a very systematic study by one of the most renowned and prestigious electrochemistry groups in the world. It was a pleasure for me as a technical editor to handle this paper. It substantiates all the statements about the truly high quality and importance of JES, one of the leading and most prestigious journals in electrochemistry.

"JES provides an excellent service to the global electrochemistry community—and thousands of ECS members—regardless of 'impact factors.'"

As of today, Dahn's JES article has received over 31,563 abstract views, over 17,000 articles downloads, and quotes in news outlets around the world.

In the article, Dahn and his research team provide full details of the new cell to create a benchmark for further research. They used a cathode material from the family of Ni rich NCM cathode materials. It has a specific capacity which is 20 percent higher than that of the cathodes used in Li-ion batteries that power today's mobile electronic devices.

The chosen, NCM 523 (50 percent Nickel, 20 percent Cobalt, 30 percent Manganese), is stable and an excellent reference and starting point for further developments. Other key components explored were graphite anodes and blends of solvents, additives, and salt for the electrolyte solutions.

Aurbach said the batteries described in the paper can be used for electric vehicles right away. "However, since the goal of the study was to provide a reliable benchmark and reference for Li-ion battery technology, the specific energy density of the batteries described is not the highest compared to what can be really reached by advanced Li-ion batteries. Based on the study, Li-ion batteries will soon be developed that make driving over 500 kilometers (over 300 miles) from charge to charge possible."

Expect more pioneering research announcements from Tesla and ECS member, Jeff Dahn, soon.


Explore further

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More information: Jessie E. Harlow et al. A Wide Range of Testing Results on an Excellent Lithium-Ion Cell Chemistry to be used as Benchmarks for New Battery Technologies, Journal of The Electrochemical Society (2019). DOI: 10.1149/2.0981913jes
Citation: Million-mile battery unveiled by ground-breaking research (2019, September 27) retrieved 19 October 2019 from https://techxplore.com/news/2019-09-million-mile-battery-unveiled-ground-breaking.html
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Sep 27, 2019
How does million-mile battery comes in?

Sep 28, 2019
How does million-mile battery comes in?


"... able to power an electric vehicle for over one million miles and last at least two decades in grid energy storage"

Nots on one charges!
Many timeses.
:-)

Sep 28, 2019
The existing batteries can already do a million miles. With energy consumption of 340 Wh/mi and a 100 kWh battery, the number of charge cycles is around 3,400 which is doable with existing batteries if you don't stress them very much.

The issue is that the batteries all break down around 10 years in use anyways. The shelf life of lithium-ion batteries is limited because of the self-reactivity of the materials, which is compounded by the wear from use.

That's why you should look at the language of the article with suspicion. They say a million miles or over two decades in grid use, but not million miles AND two decades in car use. Tesla has pulled this switcheroo many times before, where they talk about the potential of the product and make promises that can't be both true at the same time.

In other words, this isn't actually very revolutionary. Just slightly better. They're talking of a battery that cycles many times, or lasts a long time in light use, but not both.

Sep 28, 2019
Reading the paper, they do a bunch of accelerated aging tests, take the results and assume a linear capacity loss per mile per year based on the data, which disregards the fact that the wear-out mechanism gets faster over time because the coulombic efficiency of the cell decreases.

This gives predictions from 9-10 years with the cells kept at 40 C temperature, and over 30 years when kept at 20 C temperature. Their data also shows rapid capacity loss when the cell temperatures reach 55 C, but this is ignored in the projections.

They admit this is an incredibly simple model, but claim that more sophisticated models should give even better results with the assumption that the aging mechanism gets slower over time, which is known to be not the case. It ignores cases like the Nissan cars which had rapid capacity fade in California due to the temperatures. It also ignores what happens when you go below 0 C.


Sep 28, 2019
Note that the average raneg a car gets in its lifetime is about 160k miles (around here in germany accoring to the national statistics bureau)...in some other countries this may vary.

1 million miles is way, way, WAY out there. Tesla's current batteries are engineered for about 500k miles range (which is already triple of what's needed). If anything this should put to rest any fears may have about needing a costly battery replacement down the road.

So really an EV can be vastly cheaper than an ICE car (despite higher sticker price) - not only because of low running costs but because you need to buy a new car far less often.

Sep 28, 2019
Eikka
The issue is that the batteries all break down around 10 years in use anyways.
but then Eikka goes on to acknowledge that Tesla is saying -
They say a million miles or over two decades in grid use
So I guess these new batteries don't "break down in around 10 years" - so they certainly are a significant improvement. So we will be able to buy a Tesla - and run it for a million miles in 10 years. Or run it for a million miles in 20 years. In standard kind of usage of 12,000 miles a year - that would actually give you 20 years, and 240,000 miles. I wonder what the state of the batteries will be at that point. Also - wonder what battery tech will look like 20 years from now?

Sep 28, 2019
@Eikka.
They say a million miles OR over two decades in grid use, but NOT million miles AND two decades in car use.
Which article/abstract were you reading, mate? The article and the abstract BOTH say clearly that it's AND, not OR.

I quote the abstract:
We conclude that cells of this type should be able to power an electric vehicle for over 1.6 million kilometers (1 million miles) AND last at least two decades in grid energy storage. The authors acknowledge that other cell format-dependent loss, if any, (e.g. cylindrical vs. pouch) may not be captured in these experiments.
...and the article:
Dahn said: "Cells of this type should be able to power an electric vehicle for over one million miles and last at least two decades in grid energy storage."
Please, mate, do NOT base your 'assessment' on YOUR misreading of the article/paper. :)

ps: Cheer up, @Eikka! There are even better batteries in development:
https://techxplor...able-car

Sep 28, 2019
pps @Eikka.

The link in my above ps got chopped off. Here it is again:

https://techxplor...ery.html

Cheer up! :)

Sep 28, 2019
Please, mate, do NOT base your 'assessment' on YOUR misreading of the article/paper. :)


Please, don't base your 'assessment' on YOUR misreading of my comment.

I said " a million miles OR over two decades in grid use, but NOT million miles AND two decades in car use. "

Emphasis on CAR use. They're using two different scenarios with two different use cases, as per your quote:
should be able to power an electric vehicle for over 1.6 million kilometers (1 million miles) AND last at least two decades in grid energy storage.


Notice, 1 million miles for a car, at least two decades in grid energy storage. I was complaining that the did not claim two decades in CAR use, for the reason that the grid energy solution has a controlled environment where optimum conditions can be maintained...

It is already the case that EV batteries last more miles than anyone would normally drive. The sticking point is the calendar life at around 10 years for existing batteries.

Sep 28, 2019
The point about the calendar life is that the battery lasts only about as long as the average age of a car on the roads. That means most cars will need to be supplied with two sets of batteries during their lifespan, which puts the cost up tremendously and negates the advantage of having less parts to maintain.

Whether a battery lasts more than two decades when you are babying it in a controlled environment, keeping it at the optimum state of charge, temperature, and charge/discharge rate, has nothing to do with whether the same battery will last more than 10 years in a car.

It may last 12 years, or 15 years, but that's still the same problem - twice the batteries per car, because in order to reach the average road-age of around 11-12 years, most cars have to last about two decades to start with, and so the battery has to last more than two decades under non-optimal conditions in the car.

Of course you may scrap the EVs earlier, but then you're building more cars.

Sep 28, 2019
wonder what the state of the batteries will be at that point.


In the same paper, they quote earlier research done on batteries which have been run for 750 cycles over 11.7 years under controlled conditions and have retained 80% capacity. That is equivalent to driving 220k miles continuously at about 4 mph ( assuming half the time is used for charging). Very light load indeed.

The cell temperature has a dramatic effect on the wear-out mechanism. Things that put the battery above 50 C, like leaving the car out in the California sun, charging the battery at a high rate, discharging at a high rate, have an exponential effect on the capacity loss. On the other end, charging or discharging the battery below 0 C has a similar effect, so the lifespan suffers in colder climates as well.

There's a reason why your smartphone starts complaining or even shuts down when you try to use it in freezing conditions.

Sep 28, 2019
So I guess these new batteries don't "break down in around 10 years" - so they certainly are a significant improvement.


That is a question to be answered.

From the few scraps of information that leaks out of Tesla, I've read that they expect to swap the grid buffer batteries in their Supercharger stations around year 12. Tesla uses this NMC (or NCM) chemistry they're talking about in their powerwall products as well.

One more unrelated point about the NMC battery: they tried to develop it for the Model 3, but they couldn't get the costs down, so they fell back to using the same NCA chemistry as in the Model S. Whether this improvement will actually fall through depends on the price per kWh. The NMC chemistry is what the other manufacturers have been developing as well, and what the entire industry is waiting to happen. It is markedly better, especially on the fire safety side of matters, but it's unfortunately more expensive than the alternatives.

Sep 28, 2019
Eikka
Things that put the battery above 50 C, like leaving the car out in the California sun, charging the battery at a high rate, discharging at a high rate, have an exponential effect on the capacity loss
Tesla uses an active battery thermal management system. If you park your car in the hot sun - or charge at high current - and the batteries start to heat up - the TMS kicks on. The reduced range in the hot weather is caused by the increased load of the cooling system (both battery and cabin). This does not adversely affect the life expectancy of the batteries in terms of years of use. It does reduce the total miles you will get out of the battery - but if they are designed for 1 million miles - should not cause a problem.

Sep 29, 2019
@Eikka.
Please, mate, do NOT base your 'assessment' on YOUR misreading of the article/paper. :)

Please, don't base your 'assessment' on YOUR misreading of my comment.

I said " a million miles OR over two decades in grid use, but NOT million miles AND two decades in car use. "

Emphasis on CAR use. They're using two different scenarios with two different use cases, as per your quote:
should be able to power an electric vehicle for over 1.6 million kilometers (1 million miles) AND last at least two decades in grid energy storage.


Notice, 1 million miles for a car, at least two decades in grid energy storage. I was complaining that the did not claim two decades in CAR use, for the reason that the grid energy solution has a controlled environment where optimum conditions...
My apologies, mate; it was I who misread you; I understand your concern now I read you correctly. :)

ps: Has @greenonions1 answered your concern re number of years in-car life?

Sep 29, 2019
Why don't we give each building and EACH Parking Lot 'A Barcode' to Swipe, thus letting The Electric Cars to Self-Drive to those places ?

Sep 29, 2019
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