Tesla battery researcher unveils new cell that could last 1M miles
electrek.co
electrek.co
- The article is CC-BY and downloable without scribd horrible UI: http://jes.ecsdl.org/content/166/13/A3031 PDF direct http://jes.ecsdl.org/content/166/13/A3031.full.pdf HTML direct http://jes.ecsdl.org/content/166/13/A3031.full.html
- In the conclusion the authors mention: Full details of these cells including electrode compositions, electrode loadings, electrolyte compositions, additives used, etc. have been provided in contrast to literature reports using commercial cells. This has been done so that others can re-create these cells and use them as benchmarks for their own R+D efforts be they in the spaces of Li-ion cells or “beyond Li-ion cells”.
So it's science as it should be!
That's incredible.
Normally I walk into these wunderbattery threads expecting to heap reproducibility scorn (we're still waiting for solid state glass batteries, and will in all likelihood be waiting forever) but pathways to reproducibility aren't something I'm used to in battery vaporware.
I'm actually excited for battery tech, which seems weird given all the disappointment over the previous decade or two. Feels like being excited for another cancer cure in mice.
https://news.ycombinator.com/item?id=20908726
For those commenting that the discharge rate is too slow in the test, or the depth of discharge was fudged... the tests were run with a high discharge rate combined with 100% charge at storage.
> Figure 23 shows the projected fractional capacity of these NMC532/graphite cells as a function of time in years in a scenario where the cells are cycled once per day (100% DOD to 4.3 V) in a cycling event that takes 6 hours. It is also assumed that during the remaining time, cells are stored at full state of charge. It is clear from Figure 23 that these cells would provide an exceptionally long total driving range in an EV if the cells were maintained at an average tem- perature of 20°C. Even if the cells were continually at 40°C, 10 years of lifetime to 70% capacity and a total driven distance of 1,200,000 km is projected. It is worth noting that only 3650 cycles would be required for this total driven distance and 3700 cycles have been demonstrated in Figure 16.
> Most important to realize is that Figure 23 assumes 100% DOD cycling on every cycle and storage at full state of charge. If the reader reviews the literature data in Figures 1 and 2, the reader will realize that the lifetime will be much better in situations where the DOD is limited and in situations where cells are stored at lower states of charge. Admittedly, the projections in Figure 23 use the incredibly simple model described by equation 1. It is our opinion that more sophisticated models will lead to even longer lifetime projections.
If it is similar to existing batteries though... great!
In battery terminology, and this paper, charge/discharge rate is referred to as "C". Charging or discharging at 1C means a battery would be fully charged/discharged in 1 hour. A 100 Wh cell discharging at 1C would produce 100 W. Likewise, at 3C it would take 20 minutes and produce 300 W. At C/3, it would take 3 hours.
During charge the lithium ions need to intercalate into the graphite anode, which is slower than the reverse.
1) eliminates Cobalt
2) improves energy density (more range)
3) faster charge rate
4) less SOC (state of charge) swing, meaning less cost & weight
4) 5x longer lifespan
NB that most li-ion cells are rated for 300-1000 cycles at 100% Depth of Discharge. Reducing the DoD to 90% or 80% will get you thousands or tens of thousands of cycles, although it is abnormal to actually measure that long. A charge-discharge cycle at .1 C (the former standard) takes 20 hours.
[1]: https://batteryuniversity.com/_img/content/DST-cycles-web2.j...
3-4 years versus 8-10 years use makes a big difference.
2) Range is decreased. 532 has lower energy density.
3) Maybe..? But nothing truly significant. The additives in this chemistry mean a lot of heat gets generated during charge/discharge. Heat is the limiting factor during charge, so swapping directly to this would mean lower top charging speed. However with better cooling... maybe? It can sustain high charge current for longer, but not as high overall.
4) The buffer for EVs is ~10%. It's not a big factor in cost or weight.
5) Yes, 5x longer lifespan. The caveat is that they havent actually tested >3 years, but IMO this is probably a 50 year battery. The paper is more conservative and gives it 20 years.
This will be pretty enormous for grid storage, since a battery that lasts 5x as long costs 5x less. It may be important for trucks and buses, since they are much higher mileage and will want to run at 100% depth of discharge. Cars on the other hand run closer to 20%, where normal batteries will also last for many thousands of cycles.
This is only true if there is an inflation-adjusted discount rate of 0%, which is unrealistic even in this era of low interest rates. Adjusted for inflation, paying $10 now and again at years 10, 20, 30 and 40 is better than paying $50 up front would be. (By adjusted for inflation, I mean that the $10 you pay in 10 years might actually be $11, but still $10 in 2019 dollars)
In the case of batteries specifically, I think it's likely that prices drop even without adjusting for inflation. This makes the price advantage even clearer.
Time value of money is important, and IMO would be enough on its own. But opportunity cost from excluding future improvements matters too - and given the improvements in battery tech over the past decade, one that would certainly be relevant over the next five decades.
This ignores the economic realities of how projects of this nature are funded. Once projects reach a certain scale, it's much easier to find $50x once than $10x multiple times, especially when that $10x spend does not include costs that may increase over time, such as labor and regulatory compliance.
What? It doesn't seem unrealistic to me. Interest rates are increasingly negative in nominal terms, but much more frequently near zero or negative in real terms. Even in the US, 5 year real rates have averaged around zero from 2010 to present.[1]
[1]https://www.multpl.com/5-year-real-interest-rate (as you can see, real rates were going up a lot until the fed backed off and we're back to zero)
It's unfortunate they call it grid storage. Apparently you can make money by connecting a battery to the grid as the one in South Australia does make money, but I have no idea how it does it. Perhaps the price goes through the roof when a coal generator trips out and a battery can react so fast it gets first dibs on the money. The one in South Australia has certainly done that. It must be something like that as the storage is so small and the batteries so expensive they would have to get an astronomical price on what they do sell.
A house battery on the other hand - that's a different matter. The price of retail electricity at is 3 times the wholesale price, and unlike the grid battery the house usually pays nothing to charge it - it comes from the root top solar. Even so batteries aren't competitive yet, as in the return you get on installing one in a house in Australia is currently negative. But if the price drops by 1/2 it will save money by adding a battery.
I struggle to see how grid batteries fit in, but house batteries (which are really a grid battery installed at the other end of the wire) seem like they are just around the corner.
It is called the ancillary market. Basically if the grid voltage or frequency drifts off target too much, the mismatch causes semi-catastrophic shutdown of connected generation. It's... Kind of like if the timing belt in your car broke? Multi-ton generators rotating at thousands of RPM suddenly start to change direction, and they would fly apart if not for safety shutdowns.
The ancillary market exists to prevent that. Standing contracts are posted to bring fast generation like hydro power or gas turbines on the second power gets too low or too high. In Southern Australia there is very little of those resources and due to technical neglect and the governments pro-coal policies, the growth in power demand led to an unstable grid. Their limited number of fast "peaker" plants just couldn't keep up. That's why the battery made money hand over fist- 1.5 years to pay for itself, a wholly unheard of thing in civil projects like this.
Note that I've elided over a lot and ancillary markets worldwide are very highly regulated. They are very complicated, require sub-second reactions, and are generally a problem of the commons. One of the major problems that lead to the SA blackouts was the government expanding the acceptable frequency window- to ~5x what the rest of the world does (iirc). Companies immediately stopped making an effort to switch quickly and made poor long term decisions, relying on undercutting competition.
> I struggle to see how grid batteries fit in, but house batteries (which are really a grid battery installed at the other end of the wire) seem like they are just around the corner.
I think nuclear is one of the likely use cases, but it requires huge changes in carbon regulation. Nuclear is also highly capital intensive and benefits just as much as renewables from storage. A carbon tax is required to make the costs make sense though.
Ahhh, so that's how it works. Thanks.
> In Southern Australia there is very little of those resources and due to technical neglect and the governments pro-coal policies,
I struggle with that. South Australia is in the position it is is (50% renewable, 100% on occasions) because it has very little coal, and what they do have is low quality. In fact they import it from QLD and NSW. All that posturing from federal liberal politicians blaming SA Labor for choosing renewables is just that. In reality they didn't have much choice. It's very hard to be pro-coal when you don't have any.
> Nuclear is also highly capital intensive and benefits just as much as renewables from storage.
I've never thought about it - but that's probably correct. However I'm firmly in the camp of "if it was truly cheaper than coal or renewables, nuclear would be everywhere now". The data makes it fairly plain safety concerns are overblown - it's actually one of the safer forms of energy production. If it was cheap the loud protests from the anti-nuclear nuclear lobby would be ignored, just as the protests from the anti-wind lobby are mostly ignored.
[1] https://www.greencarreports.com/news/1110149_tesla-model-s-b...
The most important part of this paper is that they actually prove that optimizing for cycle and calendar life can have such incredible effects.
EDIT [s/riers/tires/;sleep]
Ultimately if you live in a hot climate the best thing to do is have a cool garage. The higher heat while out and about is not an issue, just the constant level of high heat. The only people who would get a real benefit from high temperature batteries are those without. Batteries are much more expensive than tires and the market is smaller.
Another problem is that the coolant loop needs to be kept quite clean. The fins are only about a few millimeters wide and in some cars (eg Model 3) they're electrically hot. Any grit or buildup making its way into the system is a huge problem and just having a valve that can open can cause problems.
However, they are going to have to upgrade it all anyway if we get loads of electric cars.
As for the coolant loop, I wasn't suggesting to have a valve that can open, just a closed loop to the socket and a heat exchanger that then heats the water flowing through the handle of the plug.
You then store the water in an insulated tank and use it as a preheated supply feeding your main water heating system.
In classic Netflix fashion, it’s been removed. Worth the 2$ to watch it though.
This is the company making solid state battery tech: https://ionicmaterials.com/about-us/
Now, divert government money from death industries to battery research, and we'd be talking.
It sort of depends what type of vehicle is attached to it
If this is anything like growing single-crystal parts for aircraft, it won't be cheap. The real question should be whether these new battery modules will last twice as long while remaining less than twice as expensive.
>> Controlling the charge to less than 100% state-of-charge also helps push the longevity.
Um, that is cheating. Running any battery at less than capacity will extend its life. You could put two batteries in the car, run them at 50% or alternate between them, and get double the life. No prizes for that.
https://electrek.co/wp-content/uploads/sites/3/2019/09/Scree...
Don't phones already do this? (IE: 100% is not really 100%, 0% is not really 0%.)
I don't see it as cheating, it's akin to the practical limit vs. the actual limit
I don't mind this really. Batteries degrade over time; that's kinda just how they work, and I'd much rather have 100% mean "my device is done charging" and 0% mean "my device can no longer run." The specifics of what voltage or charge level or whatever actually translates to those numbers is not important, and honestly the battery / laptop manufacturer probably knows the right settings for those better than I ever will, so it's fine.
I wish macOS/Windows allowed this natively. I'm travelling this week with my Macbook, but it's been docked for the past couple months at 100% charge. Would be better for the battery if I could keep it at 60% charge until I plan on travelling.
> Um, that is cheating. Running any battery at less than capacity will extend its life. You could put two batteries in the car, run them at 50% or alternate between them, and get double the life. No prizes for that.
I imagine the idea is that by going to X% instead of 100% fill, you extend by more than 1/X. So at 95%, perhaps we gain 20% life instead of the expected, 1/.95 ~= 1.05 -> extra 5% life.
So the anode or cathode on a battery, or even a whole AA size battery cell, is more on the scale of a microchip than a turbofan blade I think. plus the battery won't have to be subject to the same QA process of x-raying to ensure there are no microscopic cracks or defects. If one cell in your battery pack isn't as good as the rest it will just be managed around instead of subjecting all the cells to insane QA.
I'm still catching up, but it won't be expensive like that. You grow single crystals by keeping them hot and cooling them very slowly in a controlled atmosphere. Turbine blades are meant to operate in the hottest conditions in any machine on earth. Accordingly, they must be cooled at extremely high temperatures. The cost of single crystal turbine blades also pales in comparison to the cost of the blades themselves.
> Um, that is cheating. Running any battery at less than capacity will extend its life. You could put two batteries in the car, run them at 50% or alternate between them, and get double the life.
Cycle life is often plotted as equivalent full cycles. If you get two batteries, running both at 50% DoD, you will increase the amount of lifetime full-cycle equivalents by ~10-50x, depending on the chemistry.
Lowering the depth of discharge means lowering the voltage difference between the electrodes. At 4.0 V you have very few side reactions. At 4.2 V, the battery is charged. At 4.3 V (~110% charge) the battery is dangerous. At 4.6 V (~120%) the battery is plating lithium onto its anode and is about to short circuit and blow its pressure release. Fire is heavily involved. Small decreases in voltage lead to big improvements in stability.
Any battery can last one million miles if it's just sitting on a seat in a vehicle.
"For usage where our previous battery gets 300,000 - 500,000 miles, this gets a million miles". It's a real world number.