UT Austin team develops stable sodium-metal batteries using salt-based solid diluent in electrolyte
03 March 2024
A sodium-metal battery developed by researchers at The University of Texas at Austin significantly reduces fire risks from the technology, while also relying on inexpensive, abundant materials. The researchers used a salt-based solid diluent in the electrolyte, facilitating the charge-discharge cycle.
A specific type of sal— sodium nitrate—allowed the researchers to deploy just a single, nonflammable solvent in the electrolyte, stabilizing the battery as a whole. A paper on their work is published in the journal Nature Energy.
Sodium-metal batteries are an appealing, sustainable, low-cost alternative to lithium metal batteries due to the high abundance and theoretical specific capacity (1,165 mA h g−1) of sodium. However, the poor compatibility of the electrolyte with the cathode and anode leads to unstable electrode–electrolyte interphases.
Here we introduce the concept of using a salt as a diluent, which enables the use of a single non-flammable solvent, such as trimethyl phosphate. By using sodium nitrate (NaNO3) salt as a model diluent, we report a 1.1 M NaFSI–NaNO3–trimethyl phosphate electrolyte that forms a stable interface with sodium-metal anode. In addition, the formation of robust cathode–electrolyte interphases on Na(Ni0.3Fe0.4Mn0.3)O2 cathode facilitates smooth phase transitions, thus leading to stable cycle life with a capacity retention of 80% over 500 cycles at C/5 rate in Na||Na(Ni0.3Fe0.4Mn0.3)O2 cells. The work demonstrates a promising approach towards the development of safe, low-cost, sustainable high-performance sodium-metal batteries.
—He et al.
Electrolyte design strategy. a, Illustration of the components with a Na-metal battery after long-term cycling in carbonate-based electrolyte (left) and NaFSI–NaNO3–TMP electrolyte (TMP-based LHCE, right). b, Flammability tests of carbonate-based electrolyte, conventional LHCE and NaFSI–NaNO3–TMP electrolyte. He et al.
Over time, the multiple liquid solvents in an electrolyte react with other components in ways that degrade batteries and lead to safety risks. Sodium is highly reactive, posing a significant challenge to the adoption of these types of batteries. These reactions can lead to the growth of dendrites that can cause the battery to electrically short and even catch fire or explode.
In addition to the safety improvement, this new, sodium-based battery represents a less expensive alternative to the lithium-ion batteries that power smartphones, laptops, electric cars and more.
The battery also boasts strong performance. The new sodium battery retained 80% of its capacity over 500 cycles, matching the standard of lithium-ion batteries in smartphones.
Here we show a sodium battery that is safe and inexpensive to produce, without losing out on performance. It is critical to develop alternatives to lithium-ion batteries that are not just on par with them, but better.
—Arumugam Manthiram, a professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering and the lead researcher on the project
Though the researchers applied this technique to a sodium battery, they said it could also translate to lithium-ion-based cells, albeit with different materials.
Resources
He, J., Bhargav, A., Su, L. et al. (2024) “Tuning the solvation structure with salts for stable sodium-metal batteries.” Nat Energy doi: 10.1038/s41560-024-01469-y
That is a practical cycling lifetime.
Obtaining lithium is a bit problematic, aside from the other stuff in lithium batteries, including the 'P', potassium, in LFP
Since sodium batteries are pretty earth abundant, there would seem to be good prospects of making BEVs which really are competitive with ICE
Posted by: Davemart | 03 March 2024 at 03:12 AM
I had a poke around to try to find out what the current state of play in sodium batteries is.
This seems to be a good overview:
https://www.machinedesign.com/materials/article/21274631/sodiumion-batteries-are-on-the-horizon-how-do-they-measure-up-to-lithiumion
It is mainly a Chinese thing, with both CATL and BYD going big on it.
However rumours that it would make its way into the BYD Seagull mixed with some lithium did not happen, yet anyway:
https://carnewschina.com/2023/11/20/sodium-ion-batteries-are-real-in-china-byd-to-build-30-gwh-sodium-battery-plant/
Posted by: Davemart | 03 March 2024 at 03:54 AM
The paper is paywalled, but looking at the open access pictures some interesting details can be seen. This is a metal battery, >3V and 100-120 ah/kg. So it has a good energy density, comparable to current li-ion batteries.
As most metal batteries, lifespan is not that good.
It would be nice to see more details as cathode composition, behaviour under differente charging/dischargin rates etc...
Posted by: peskanov | 03 March 2024 at 02:51 PM
@Davemart
The “P” in LFP batteries is for Phosphate, a a compound of phosphorus and oxygen.
There is no Potassium in LFP batteries. Potassium is an alkali metal like Lithium and Sodium. There are Potassium Ion batteries. Such as this battery from UT Austin
“Low-Cost High-Energy Potassium Cathode“
https://pubs.acs.org/doi/10.1021/jacs.6b12598
Group 1 is a spinoff of the UT research: https://group1.ai/
BTW there are 300 Billion tons of potentially exploitable resources
of phosphate rock. Most is used in agriculture and that is where the overuse is.
https://www.ocpgroup.ma/what-is-phosphate#:~:text=Phosphate%20rock%20is%20processed%20to,to%20animal%20feed%20and%20electronics.
We need regenerative agriculture that limits the use of all fertilizers.
Posted by: Gryf | 03 March 2024 at 06:31 PM
Sodium is highly reactive...
There is a problem.
Posted by: SJC | 03 March 2024 at 07:34 PM
"Since sodium batteries are pretty earth abundant, ...."
Well, I knew that Sodium is an abundant element but didn't know that sodium batteries were also abundant in nature. That saves all the trouble of manufacturing them. Learn something new every day!
Posted by: yoatmon | 04 March 2024 at 06:26 AM
@Gryf:
Sorry, typo. I of course meant phosphate, which since it is essential to feeding us, caused my reservations, not so much about present use levels, but indefinite expansion of this as a cheaper alternative to other lithium chemistries.
Posted by: Davemart | 04 March 2024 at 07:48 AM
@SJC:
Lithium is highly reactive too, which is why like sodium it works for batteries.
Posted by: Davemart | 04 March 2024 at 07:51 AM
@yoatman:
:-0
You mean sodium batteries DON"T grow on trees? Shocker!
More seriously, your point is quite correct, you can make sodium batteries using very similar other materials to lithium ones, with similar hassles about cobalt, nickel and whatever, so it is just the sodium which is more earth abundant than lithium and cheaper.
But apparently there are other alternatives:
https://www.linkedin.com/pulse/comparision-sodium-ion-batteries-lithium-ion-current-status-tharad-7zshe
' An obvious advantage of sodium is its natural abundance, particularly in saltwater. Another factor is that cobalt, copper and nickel are not required for many types of sodium-ion batteries, and more abundant iron-based materials (such as NaFeO2 with the Fe3+/Fe4+ redox pair) work well in Na+ batteries. This is because the ionic radius of Na+ (116 pm) is substantially larger than that of Fe2+ and Fe3+ (69–92 pm depending on the spin state), whereas the ionic radius of Li+ is similar (90 pm). Similar ionic radii of lithium and iron result in their mixing in the cathode material during battery cycling, and a resultant loss of cycleable charge. A downside of the larger ionic radius of Na+ is a slower intercalation kinetics of sodium-ion electrode materials.
Which causes me to say:
'Help! Gryf! SJC!' as both are more fluent in ancient Chinese than I.
But my guess is that that means that high power output as opposed to high energy density is tougher with those other formulations.
They are trying to use batteries in lots of other applications than transport though, for stationary storage etc, so if I have understood what they are saying right, and that is a big if, then there are many uses for sodium batteries which will reduce the demand for less earth abundant materials.
And perhaps those limitations can be finessed for transport.
I don't know what forumlation BYD and CATL are going for for their tranport focussed sodium batteries, but presumably they are at present sticking to similar formulae to their lithium batteries.
However that does not necessarily mean that more earth abundant materials will forever be impossible to use in sodium batteries for transport.
Posted by: Davemart | 04 March 2024 at 08:06 AM
CATL's current sodium battery for cars uses nickel, magnesium and cobalt, however Northvolt's sodium battery for storage uses none of those:
https://think.ing.com/articles/can-sodium-ion-batteries-replace-lithium-ion-batteries/
' Northvolt’s new battery has an energy density of more than 160 watt-hours per kilogramme, an energy density close to that type of lithium batteries typically used in energy storage, where size is not a problem. The Swedish group said that their battery has been designed for electricity storage plants, but in the future could be used in electric vehicles.'
Posted by: Davemart | 04 March 2024 at 09:19 AM
@Davemart
Your reference about CATL and Sodium Ion batteries is poorly written.
It states:
“ CATL, the world’s largest battery maker, uses oxides containing metals such as nickel, cobalt or manganese in their sodium-ion batteries - this makes these batteries more expensive, than the battery developed by Northvolt.”
This is incorrect.
Both Northvolt and CATL use Prussian White Cathodes.
From the CATL website: https://www.catl.com/en/news/665.html
“ CATL has applied Prussian white material with a higher specific capacity”
The Group1.ai reference has an interesting slide presentation that uses a room temperature Liquid Na-K Anode that is both long life and dendrite free. The use of this electrolyte plus the Group1 anode would make an interesting battery.
Slide 5 shows the Sodium Prussian White Cathode (Na2MnFe(CN)6 Cathode).
Reference:
https://static1.squarespace.com/static/60f700f696c8122307175459/t/653bfe0937fa641f389f8a53/1698430495350/Potassium+ion+battery-+Group1
Posted by: Gryf | 04 March 2024 at 09:48 AM
Hi Gryf;
You are frequently firing above my head! Or at least from a different set of reference points.
'Prussian white' calls to mind for me the several battle horses of Frederick the Great, which presumably have little to do with batteries. ;-)
But more to the point, what I often find when trying to sort out what is happening in batteries, is that advertently or not several different levels of development and for different applications are often confounded.
CATL (and BYD) are developing sodium batteries for both stationary storage and then more energy density demanding transport applications, and may apply different solutions to them,
So the bottom line is that both CATL and BYD have a variety of options being developed for sodium batteries, including mixing them with lithium batteries in cars, and to me at least it is not clear what they are using where.
Posted by: Davemart | 04 March 2024 at 11:25 AM
"Sodium is highly reactive, posing a significant challenge to the adoption of these types of batteries. These reactions can lead to the growth of dendrites that can cause the battery to electrically short and even catch fire or explode."
Sodium has been known to catch fire when exposed to moisture or air,
this has happened in nuclear reactor coolant systems.
Here they're talking about using sodium metal as an anode.
Posted by: SJC | 04 March 2024 at 12:11 PM
"Sodium is more reactive than lithium because sodium is larger in size. Outermost electrons are less tightly held in sodium than in lithium. As a result, sodium loses its outermost electron more easily than lithium. Hence, it is more reactive than lithium."
Posted by: SJC | 04 March 2024 at 12:14 PM
Sodium has 3 electron shells while lithium has only 2 electron shells
Sodium can donate its electrons more easily because the valence electron is further from the nucleus and the force of attraction between both is weaker.
Whereas lithium donates its electron less easily because the valence electron is closer to the nucleus and the force of attraction between both is stronger.
This is why sodium will "react more" with oxygen compare to lithium
Posted by: SJC | 04 March 2024 at 12:17 PM
Thanks SJC.
Checking if you were giving me the true stuff, I came across this:
https://www.quora.com/Why-does-lithium-react-less-vigorously-than-sodium
' Michael Flynn
BSc Hons Newcastle UniversityUpvoted by
Gary Hiel
, College Chem Prof and former Industrial Organic ChemistAuthor has 909 answers and 2.5M answer viewsUpdated 4y
Related
How is lithium a better reducing agent than sodium in terms of electrode potential, although sodium is more reactive than lithium?
Sodium is regarded as being more reactive than lithium. It has a lower 1st ionisation energy.
Yet lithium has an anomalously large and negative electrode potential.
1st ionisation energies are measured in the gaseous state which, for lithium is ΔH
for:
Li(g)→Li+(g)+e
However electrode potentials refer to this process in aqueous conditions:
Li+(aq)+e⇌Li(s)
for which Eo=−3.04V
whereas the value for the sodium half cell is -2.71 V
To explain this you need to consider the individual energy changes when a metal becomes an aqueous ion. The metal must be atomised, ionised and then hydrated by water molecules.
It is the 3rd step which accounts for the anomaly. The enthalpy of hydration of a lithium ion is ΔH
for:
Li+(g)+(aq)→Li+(aq)
Which = - 507.1 kJ/mol
The same value for sodium is - 395. kJ/mol
This difference is due to the small size of the lithium ion compared with sodium resulting in a higher charge density. A high charge density leads to a more negative hydration enthalpy resulting in a more negative electrode potential.'
Unfortunately I have no clue what any of that means, or whether it has any applicability at all to usage of sodium versus lithium in batteries!
But it might be of interest to you and Gryf, conceivably.
Posted by: Davemart | 04 March 2024 at 01:12 PM