Researchers use multivalent cation additives to inhibit dendrite growth in rechargeable batteries

08 June 2022

Researchers at Tohoku University have devised a means to stabilize lithium or sodium depositions in rechargeable batteries, helping keep their metallic structure intact. The discovery prevents potential battery degradation and short circuiting, and paves the way for higher energy-density metal-anode batteries. An open-access paper on the work appears in the journal Cell Reports Physical Science.

Multivalent cation additives modify the solvation structure of lithium or sodium cations in electrolytes and contribute to flat electrodeposition morphology. Li et al.

Scientists are ever-seeking to develop safer, higher-capacity, and faster charging rechargeable batteries to meet energy needs sustainably. Metal anodes currently show the highest promise to achieve that goal. However, the use of alkali metals poses several problems.

In a rechargeable battery, ions pass from the cathode to the anode when charging, and in the opposite direction when generating power. Repeated deposition and dissolution of metal deforms the structures of lithium and sodium. Additionally, fluctuations in diffusion and electric fields in the electrolytes close to the electrode surface leads to the formation of needle-like microstructures called dendrites. The dendrites are weakly bonded and peel away from the electrodes, resulting in short circuiting and decreases in cycle capacity.

To solve this problem, a research team led by Hongyi Li and Tetsu Ichitsubo from Tohoku University's Institute for Materials Research added multivalent cations, such as calcium ions, that altered and strengthened the solvation structure of lithium or sodium ions in the electrolyte.

… focusing on CaTFSA2 as an exemplary additive, we reveal that dendrite-free morphology upon alkali metal electrodeposition can be attained by modifying the solvation structures in dual-cation electrolytes. Addition of Ca2+ promotes alkali cation (Li+ or Na+) to form the contact ion pairs (CIPs) with the counter anions, which replaces the solvent-separated ion pairs that commonly exist in single-cation electrolytes. The strong binding of the CIPs slows the desolvation kinetics of alkali cations and, consequently, realizes a severely constrained alkali metal electrodeposition in a reaction-limited process that is required for the dendrite-free morphology.

—Li et al.

For their next steps, Li and Ichitsubo are hoping to improve the metal anodes’ interfacial design to further enhance the cycle life and power density of the batteries.

Resources

• Hongyi Li, Masaki Murayama, Tetsu Ichitsubo (2022) “Dendrite-free alkali metal electrodeposition from contact-ion-pair state induced by mixing alkaline earth cation,” Cell Reports Physical Science, doi: 10.1016/j.xcrp.2022.100907

Since I am a fan of sodium batteries, I am particularly interested that this can help longevity in those as well as lithium ones.

That will help my, and much more importantly, Toyota's chief criticism of lithium battery technology, that it is in reality too expensive, and likely to remain so for ages, to power the average Joe's car.

Sodium should be way cheaper, if it can be done.

Davermart,
Toyoda does not seem to be much of a visionnaire lately. After the hit against the Li-ion cartel (Sony, Panasonic, Samsung, Sanyo) in 2016, competition has lowered the cost to $80-100/kwh. Specially for LiFePo4. While$80 is still higher than ideal, you don't need to go much lower to fix the transportation problem. Keeping there consistently would be enough.

Li-ion has been (for years) cheaper than the NiMH solution (Toyota's obsession) for years.

Lithium is a problem, but I think is overrated. Lithium was not a significant part or Li-ion cost in the past; the large price rise is changing that situation; but, for how long? As the price rises, mines are opened fast. Lithium is a totally underdeveloped resource, there was never too much of a use of it.

The next generation of battery design looks like it will be composed of earth abundant elements. This research looks at Calcium additives to enhance lithium and sodium metal anodes. Research at the Yao Group University of Houston also is enhancing sodium metal anodes.
“An electrochemically stable homogeneous glassy electrolyte formed at room temperature for all-solid-state sodium batteries”
https://www.nature.com/articles/s41467-022-30517-y
Drexel University with the Gamma Sulfur cathode could be the answer for a long life cathode.
https://drexel.edu/now/archive/2022/February/lithium-sulfur-cathode-carbonate-electrolyte/
The “Goldilocks Battery” of Lithium or Sodium Sulfur looks like it is developing soon.

@peskanov:

'Fully electric cars are like a beautiful flower on a high mountain, where unfortunately few can reach'

There has been a gigantic hoovering sound of wealth transfer upwards, leveraging grossly immature technology to subsidise the wealthy at the expense of the masses.
If it were about low pollution, it would be the folk catching a bus who would get the subsidy, not people buying $40k cars using critical and vastly polluting minerals. Those particulate emitting tire shredders are the fake ecology, not Toyota Yaris cars. Someday we may have batteries or whatever able to do the job, that has little to do with the regressive money grab which has taken place so far. Check out the average sales price of a car in the world. A world where the vast majority of car owners have more similar incomes to new car buyers in India than the small proportion of Americans in their massively inequitable society who buy a new car still can't afford an EV. Selling the lie that everyone can have it all, to justify and validate upward wealth transfer and seizure has been very successful. And in some vastly inefficient and grossly unjust fashion this con job has indeed facilitated the eventual electrification of transport and decarbonisation. @Gryf Lets hope so! The real problem with batteries is their cost, not so much their energy density. I would have thought that the main material cost of NMC LI Ion batteries would be the cobalt and nickel. LiPo may well be cheaper, but it is rather heavy (and possibly bulky) - better for stationary storage (or maybe trains). It's not cheaper if it takes more cells due to the low energy density @mahonj: That is why things like CATL's sodium ion batteries will hopefully become very important - they use cheap abundant materials, and if various obstacles can be overcome, enough energy density. My view would also be that the notion that it is OK to run around in vast heavy cars, often with one occupant, is still prevalent. Oddly, if that is insisted on, some combination of fuel cells and batteries may be optimal, although I would advocate more rational solutions tailored to moving as many people as conveniently as possible rather than vast bling cars, electric, hydrogen etc or not. In cities, electric bicycles rather than electric or SUVs and bling cars. Hire cars as and when needed for longer distance. Davemart, Toyoda says Li-ion EVs can't scale, but still insist in using a rare earths battery (NiMH) in all Toyota's hybrids and now FCEVs. I have a serious problem understanding his vision. Criticizing subsidies is fine, but I want to know where is your threshold for$/kwh. Because the LiFePo4 price I mentioned is happening now, without subsidies.
At some price point even the most ardent BEV critic have to admit it makes sense economically. I just happen to think we are already there.

As defined by the electromotive metals table, lithium was a good starting point for selecting an battery element b/c it has the highest potential difference between other elements and has an available valence electron. However, Sodium is very close behind. And as we know sodium also is more abundant than Lithium. Hopefully this will lead to cheaper, more energy dense battery chemistry. As stated by Gryf, a Na Ion battery using another abundant element, E.g., Sulfur(S), could revolutionize the storage industry, pricewise.
It will be interesting to see where we are this time next year, With the amount of research going on, something great is bound to occur in battery technology.

Absent from this discussion so far is the consequence of vastly longer cycle life to battery total cost of ownership (TCO).

Dahn at Dalhousie has recently reported on chemistry improvements that will produce a 1,000,000 mile, one hundred year battery.

The battery does not use exotic materials.

@peskanov:

? Nickel metal hydrate batteries don't use rare earths, at any rate in any substantial quantity.
I can only imagine that you are thinking of Nickel metal cadmium.

@electric car insider

Yep, increased life is great, although it should be pointed out that going for very fast charging makes that far more difficult.

Its best application though is not in a giant BEV battery.

Now maybe you can swap a battery out at the end of the rest of the vehicle's lifetime, although some of the notions of building the battery into the structure to by the likes of CATL make that far more difficult.

But in practical terms for most cars, around 3-500,000 miles is fine, after which the rest of the car is difficult to maintain, and pretty tacky.

Far better applications are in trucks, and yes, I certainly advocate BEV trucks, with hydrogen fuel cells and hydrogen ICE trucks only really needed for long distances, but also for PHEVs.

A high cycle life means that even though it is way less than the 2,000,000 or so being talked about for big battery BEVs, it can comfortably be designed for the 3-500,000 lifetime needed for a private car, even if the battery is only 16KWh or so, especially since there is no need for fast charging.

That working with a fuel cell is a pretty awsome combination, especially for some of the HT PEMS coming along.

I repeat, I am an advocate of batteries, but applied and costed realistically, not shoved out regardless of the cost ( to others ) courtesy of the propaganda of the greatest salesman of the age.

Davemart,
I could be wrong with the Toyota's battery, but usually NiMH needs Ce, La, Nd.
All of them classified as rare earths.
That's one of the reasons NiMH are so expensive (plus the large use of Nickel of course).

Again; what's your targe price for batteries, at which point do you consider them acceptable for general use in transport?
$50/kwh?$30?
$10? @electric-car-insider.com, while this is interesting, there is a limit where higher lifespan means nothing. Most cars go to heaven around 300k km, even with an engine in working order. Very long lifespan batteries are very interesting for heavy duty vehicles, like forklifts, quarry trucks, buses, trains... @peskanov: Thanks for the correction, bringing to light facts I was unaware of. Here is a link substantiating your point about rare earths in NiMH: https://www.researchgate.net/publication/302515862_Chapter_10_Rare_Earths_in_Rechargeable_Batteries That is not the only source of rare earth use in an EV though, as the electric motors typically contain them. What Toyota, along with a few others such as BMW and Polestar have, is comprehensive energy and materials analysis on a lifecycle basis of what goes into their cars, and what it takes to produce them. In addition, the 1-1.5KWh battery in a hybrid is a very different matter to the 50-150KWh battery in a BEV. Rare earth use in variants which use it in the motor will also scale with output, so the very powerful motors used in the supposedly green bling cars, produced by companies often with no published lifecycle accounting at all, just press releases proclaiming how green they are ( massive subsidies, please ) do not inspire me with confidence. @peskanov: To reply to your point about battery prices, I find it difficult to give a definitive answer, as breakeven depends on the application. And it is another area where bull has reigned, for the purposes of getting subsidy, just chuck the well off another few billion in subsidies and tax breaks, and we will have something cost effective 'real soon' So all sorts of strategies were employed to bamboozle, often via surveys of interested parties to see what they forecast for prices! Much like asking detergent manufacturers whether they get shirts whiter. Another ploy has been to routinely confound costs at the cell level with costs at the pack level, and without any margin. Where bottom up costings are used, and some of the technological leaps blithely assumed not built in, things get a lot stickier, and a lot more conservative. At the moment, with raw materials prices rising, costs are going up, not down, and notions of manifest destiny in battery prices are on hold anyway. Just the same, your question is a fair one, which I do not seek to evade. But the answer must be ' it depends on the application and legislative environment' Much though Trumpians might wish otherwise, we are not going to return to the good old days, of releasing as much GHG toxic exhaust as the companies fancy, so my answer would be that in some use categories and applications batteries are already economic, or economic enough. And what is economic as battery prices drop, and they will at some stage, is again dependent on the same two factors. If we are going to enable SUV type vehicles, often with a sole occupant, then in my view fuel cells are a better option. But I certainly do not advocate that. And the smaller, lighter and more range limited the vehicle, the higher prices can be borne for batteries. I think I am living in the city of the future here in Bristol, England: https://mashable.com/article/lime-e-scooters-london Street scooters, buses electric smart cars where needed etc can do the job There is not and never has been a case for providing public funds for heavy private vehicles, not only consuming vast resources in the build, but for starters particulates from shredding tyres. But to answer your question directly, the figure commonly used for universal replacement of ICE with batteries, is around$50 at the cell level.

You can't hit that with current batteries, but something like sodium can, sometime.

They sold current battery subsidies on a fake prospectus of more continuity with something which will actually do the job than is the case, although it does help to some degree.

And of the top four companies for battery research and development, one is Toyota, and another is their close associate Panasonic.

As soon as there really are cost competitive batteries against ICE for BEVs, there will be plenty with a Toyota badge on.

But they deal with present reality, to try to serve the average Joe, not fake prospectuses to scam subsidies and pump stock prices.

Davemart,
Neodymium in motors are optional. Wound motors like the ones used by Renault and Mercedes work just as well, they are just more difficult to manufacture.

I think you overrate Toyota knowledge on batteries. They are certainly not Panasonic.
Toyota studied existing NiMH chemistries in the 90's and developed them for serial hybrids, kudos to them.
But they did nothing more in the field for the next 20 years. They have some patents, made some claims (in Magnesium batteries, with no results) and avoided Li-ion like the plague.
Now they are alone using NiMH. Any similar use is covered by LTO today, and cheaper. But they refuse to change.

Call me an optimist, but I really believe $50/kwh (or it's equivalente after inflation gets stabilized) is at hand, at least for LiFePo4 and Lithium-manganese flavours. Dry cell technology already has the potential to move us there. I think the concept of a million mile battery may be widely misunderstood. If the world had a million mile battery today (and assuming a reasonable price), the legacy OEMs might shrug and do nothing. Ford for example, has publicly discussed wanting batteries with lower life. But you can be certain that some entrepreneur will figure out a way for that to be an absolute game changer. Tesla has already discussed this enough to be certain that they'll take a serious run at it. The idea that a car has to be discarded at a 200k miles is only because most automakers want it that way. Unless a car is destroyed in an accident, there's no reason it needs to be destroyed when the seats get worn or the paint faded. (both of these are imminently preventable). Many of the systems that cause maintenance problems don't even exist on BEVs. Look at the classic car market, it's a matter of care, and continued parts availability. Better yet, look at the General Aviation industry. The average age of a general aviation aircraft is about 30 years. Many in-service aircraft, used daily by flight schools, are over 40 years old. TBO on a typical ICE is about 4,000 hours. For an electric motor, it's about 100,000 hours. (273 years if you drive an hour per day) When your motor and battery will last 100 years, you'll want the chassis to hold up that long also. Using something other than salt on the roads in cold climates would help, or, as Tesla and BMW have demonstrated, aluminum and composites. Would you pay more for a car that can last 1 million miles without major repair? I would. Long endurance cars will be passed through multiple generations like houses, and will not depreciate as rapidly. Those two facts will change the acquisition and financing industries entirely. @electric-car-insider.com, While I sympathize with your view, I fear current fast development of EVs and current lack of standards/lack of documentation situation will make current EVs unsupported in a decade. I would support and buy an open-source EV, where battery size & interface is standarized, and same for inverter, motor and charger. That would make economic add long life EVs possible. But I just don't see that happening. @peskanov I can’t agree with your evaluation of Toyota. Since their inception they have been at the forefront of the electrification of transport, pouring billions in over decades, and were the ones who developed the supply chains for electric hybrids, which supply chains enabled BEVs In their patent portfolio etc they, together with Panasonic, are objectively and traceable two of the four top holders. And any use of rare earths in rare earths in their 1.5KWh hybrid battery packs is hardly comparable to the many issues in building and recycling the 50+ KWh packs in a BEV. For total emissions including build, lifecycle and particulate emmissions including non exhaust a Toyota Yaris hybrid remains the truly ecological choice, beating$40k BEVs weighing several tons with vast and inappropriate acceleration.

But as they get truly, not fake, better batteries available, Toyota will continue to do what it does, build cars for everyman, as opposed to being a business only enabled by loose money, stock pumps and subsidy for the wealthy

Agree, Peskanov, that there’s plenty of room for innovation in standardized, interchangeable parts and easier modular servicing.

But consider the classics that go up for sale on these auctions. Well into six figures for a well maintained or restored muscle car from the early ‘70s.

Those cars are drivable and as long as parts are available or can be fabricated, they can perform perfectly well on modern roads. With a handheld or dash mounted iPad GPS, you even get modern navigation and infotainment.

In General Aviation, this is even more so - digital gauges are now drop in replacements for vacuum gyros and pitot static gauges. Modern engine monitors vastly improve the efficiency and longevity of the engines.

IPads mounted in the panel provide full “glass cockpit” capabilities with terrain, weather, traffic and airspace displays.

When properly equipped, these 50-60 year old aircraft are fully as capable as their modern $500k to$750k counterparts in terms of real-time cockpit information.

Tesla, with their over the air updates, have shown how cars can be kept up to date in ways never offered by the legacy OEMs. They also have computer and sensor upgrades available for some applications.

The auto industry is only getting started on this because for the first time in a century, there are real innovators on the scene.

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