Lithium-sulfur battery retains 80% charge capacity after 25,000 cycles
111 points
by T-A
19 hours ago
| 7 comments
| techxplore.com
| HN
elvircrn
14 hours ago
[-]
---------------------------------------------------------------- Dear battery technology claimant,

Thank you for your submission of proposed new revolutionary battery technology. Your new technology claims to be superior to existing lithium-ion technology and is just around the corner from taking over the world. Unfortunately your technology will likely fail, because:

[ ] it is impractical to manufacture at scale.

[ ] it will be too expensive for users.

[ ] it suffers from too few recharge cycles.

[ ] it is incapable of delivering current at sufficient levels.

[ ] it lacks thermal stability at low or high temperatures.

[x] it lacks the energy density to make it sufficiently portable.

[ ] it has too short of a lifetime.

[ ] its charge rate is too slow.

[ ] its materials are too toxic.

[ ] it is too likely to catch fire or explode.

[ ] it is too minimal of a step forward for anybody to care.

[ ] this was already done 20 years ago and didn't work then.

[ ] by this time it ships li-ion advances will match it.

[ ] your claims are lies.

----------------------------------------------------------------

Source: https://news.ycombinator.com/item?id=26633670

reply
hilbert42
2 hours ago
[-]
Right, all your points may be correct or are perhaps possible.

Now would you kindly cite authoritative sources and references so we can verify your assertions.

reply
joshu
11 hours ago
[-]
there are uses for non-portable batteries
reply
dyauspitr
14 hours ago
[-]
What other boxes does it check because otherwise it’s viable for home scale uses.
reply
senectus1
11 hours ago
[-]
this is the stupid binary-ism that is holding us back. "its no good for X, so its immediately discounted for ANY solution".

The issue plagues moving forward with other energy solutions like hydrogen.

reply
Dylan16807
6 hours ago
[-]
What's hydrogen a solution for?
reply
chgs
3 hours ago
[-]
Power supply to remote temporary areas like construction sites. Let’s say you need 100kW for 12 hours a day for a month to the middle of nowhere. You could run new power lines and get the connected, over land you don’t own, taking months. Or you could bring in a hydrogen generator and ship in new bottles to “recharge” it.
reply
wqaatwt
4 hours ago
[-]
More affordable blimps?
reply
toomuchtodo
10 hours ago
[-]
reply
happosai
17 hours ago
[-]
Sulfur in mining tailings is huge problem ( https://en.wikipedia.org/wiki/Acid_mine_drainage ). This one reason there is so much research in Li-S batteries. Plenty of material innovations have come from people looking at mine tailings and wondering if something useful could me made of it.
reply
rpaddock
17 hours ago
[-]
For 22 years I designed the electronics controls that ran Longwall Coal Mining Machines. I've been in many mines.

The problem with extracting things from tailings is that they are often contaminated with low levels of Thorium. Extracting the other things like Lithium, Sulfur etc, starts to build up the quantity of Thorium. Which sounds good if you want to build a molten salt Thorium reactor; I understand that China and India have prototype to come on line around 2027. Based on designs and experimental units that the US did in the ~1950s.

The tailing problem is that the company is how handling Nuclear Grade Material which causes the Nuclear Regulatory Commission (NRC) to show up at the mine site. No mine wants to deal with this paper work, and health ramifications, headache so the tailings are not used.

If the profit ratio to headaches would improve things might change.

reply
mapt
15 hours ago
[-]
This seems backwards.

The tailings do not become nuclear waste when we decide to use them for something.

reply
dcrazy
15 hours ago
[-]
Perhaps the problem is that you are either refining away the thorium, or refining away as much non-thorium as you can. Either way you end up with mostly-thorium, and we know that radioactive stuff gets angry in large groups.
reply
DennisP
14 hours ago
[-]
Thorium does not get angry, because it's only slightly radioactive and it's not fissile. To start up a thorium reactor, you need enough plutonium or uranium spitting out neutrons to convert plenty of thorium to U233, which is what fissions and makes energy.

If you want an actual bomb, you need that U233 without any thorium, because the thorium mostly just turns to U233 when it absorbs a thermal neutron (i.e. slowed down by a moderator like graphite). In a bomb you're relying on fast neutrons.

Read enough books/articles on thorium reactors and you'll come across a photo of the US thorium stockpile, which is a great big stack of pure thorium bricks.

reply
westmeal
15 hours ago
[-]
Everythings ass backwards when bureaucrats or the military get involved.
reply
mchannon
16 hours ago
[-]
It's not sulfur so much as sulfate.

It doesn't always come from mining. A huge problem with acid rock drainage (ARD) showed up when they built a freeway in Pennsylvania by merely exposing the rock.

The concept of making batteries out of drainage because both contain sulfur is like making socks out of cow manure because both contain carbon. There's so much of the latter that you could never use it all, but also the ingredient is dirt cheap in pure form.

I have a side project that could convert ARD into industrial strength sulfuric acid, which is unbelievably difficult to buy and transport, despite it being the most common industrial chemical in the world after water.

reply
mapt
15 hours ago
[-]
Acid rock drainage is currently devastating Arctic streams with the melting of pockets of permafrost, which are in effect strip mines.

https://youtu.be/Lxfpgqn6NOo?feature=shared

One of the larger sinks for waste sulfur might be stratospheric injection for geoengineering, which is looking increasingly likely.

reply
pfdietz
16 hours ago
[-]
It's sulfides like pyrite that, when exposed to air, are oxidized by bacteria to sulfate.

There's an enormous belt of pyrite in Spain that has caused a river, the Rio Tinto, to be one of the most acid rivers on the planet.

https://en.wikipedia.org/wiki/Rio_Tinto_(river)

reply
mapt
15 hours ago
[-]
I'm not sure the belt of pyrite is best labelled as the cause here.

It might have something to do with the inferred activities of Rio Tinto, a transnational corporation that is one of the largest mining firms in the world.

reply
duskwuff
8 hours ago
[-]
The river was polluted millennia before the Rio Tinto company came into existence. There's been mining operations along the Rio Tinto since ca. 3000 BC.
reply
cyanydeez
15 hours ago
[-]
Yes, and it's not just "random" sulfur, it's integral to the geologic complexes that miners look for to get the minerals they want.

Think of it like the husk of a corn cob, or the cob of your corn. It's a byproduct of the very things we're looking for in mining.

The only other activity that could get hose minerals is indistinguishable from magic.

reply
somat
9 hours ago
[-]
reply
pfdietz
16 hours ago
[-]
Once we stop using fossil fuels, maybe sulfur in mine tailings will become a valuable resource. Today, sulfur comes from desulfurization of fossil fuels.
reply
cyanydeez
15 hours ago
[-]
so long living batteries are a _good thing_.

Almost everything humans do requires an extensive life cycle analysis.

but you know, lets just cut everything and pretend that'll improve our assessments of reality.

reply
mrabcx
17 hours ago
[-]
"lithium-ion batteries .. degrade after just 1,000 cycles" If you charge your car battery twice a week and complete a full cycle then we are still talking about like 9 years to reach 1000 cycles. If you charge your phone every day, and do a full cycle, then we are close to 2.7 years. But you will probably not do a full cycle. So, I guess lithium-ion batteries are not really that bad.
reply
hackingonempty
17 hours ago
[-]
Don't forget calendar life. Lithium batteries degrade over time even if you do not cycle them. The life of the commonly used chemistries is only around 3 years.
reply
r00fus
17 hours ago
[-]
Explain my 7.5 year old EV with 95% battery health and 65k miles driven?

Your 2nd sentence has issues with reality.

reply
DylanDmitri
16 hours ago
[-]
Some EVs start with capacity “gated off” to limit the depth of early cycles and provide a more graceful degradation.
reply
r00fus
15 hours ago
[-]
But a lifetime of 3y doesn't jive with why my 7 year old vehicle is mostly fully functional. Even with 10% over-provisioning (amazingly expensive 7y ago), that's only a 15% reduction in 7 years.

The statement "The life of the commonly used chemistries is only around 3 years" is completely misleading and probably inaccurate.

reply
freedomben
15 hours ago
[-]
I don't know about the 3 years number, but generally speaking battery lives are estimates/averages based on statistics. If you have a battery that was well cared for it will outperform the average. Also sometimes it's just dumb luck. One aberration isn't nearly enough data to throw out the entire premise
reply
saidinesh5
15 hours ago
[-]
It depends on your usage too, along with the exact chemistry and form factor of the lithium battery.

A lot of people report lithium batteries swelling up in their phones/tablets around 3-4 years of usage.

reply
mapt
15 hours ago
[-]
Phone batteries are lithium polymer pouch cells, the least durable type commonly used. Car cells with lithium ion NMC cylindrical cells are much better, and LIFEPO4 in turn is several times more durable than that.

You would be wise to insist on an EV with LIFEPO4 batteries in the sense that calendar lifetimes are more likely to be on par with traditional engines.

reply
kccqzy
14 hours ago
[-]
The explanation is simple. OP said commonly used chemistries. That would be something like LCO. Your EV battery is probably NMC.
reply
api
17 hours ago
[-]
Degrade to what extent? I have a 12 year old Nissan Leaf that's lost maybe 25% of its range. Still absolutely usable as a neighborhood car.
reply
neogodless
16 hours ago
[-]
A 2013 Nissan Leaf should get 60-75 miles of range (depending on how much of thebattery you use, as well as climate, and other driving conditions). If it got ~80 miles new, it would still get 60 miles now. That might be enough for someone to make a short commute, though unless they have relatively fast charging at home, a 20+ mile commute 5 days a week might be tough to pull off. But most errands would fall well within the existing / remaining range.
reply
chgs
3 hours ago
[-]
50 mile round trip at 3 miles per kWh would be under 20kWh, or 1.6kW for 12 hours, about the same as a plug in heater on max, easily doable in a normal socket let alone a dedicated charge circuit.
reply
zardo
15 hours ago
[-]
I think most testing uses 80% capacity as the cutoff point. Largely because that's when the loss in capacity really slows down.
reply
fredrikholm
16 hours ago
[-]
> neighborhood car

Not familiar with that term, what does it mean? Shared ride? A car for walking distances?

reply
BobaFloutist
16 hours ago
[-]
I think they mean "city car" as opposed to "road trip car" or "rural car."
reply
Cupprum
14 hours ago
[-]
Going to work, groceries and so on, the regular stuff.

If the city was walkable, you would not need such a thing as neighborhood car, you could just use a bike, but apparently as a society at many places we have decided that the cars are the best mode of transportation ever.

reply
globular-toast
16 hours ago
[-]
An electric wheelchair.
reply
nuancebydefault
16 hours ago
[-]
If it has moved like 250K km then it is impressive.
reply
magicalhippo
13 hours ago
[-]
There's also some research[1] suggesting that dynamic cycling extends lithium-ion battery life, compared to the fixed charge/discharge cycles typically done in a lab setting.

In this study, we systematically compared dynamic discharge profiles representative of electric vehicle driving to the well-accepted constant current profiles. Surprisingly, we found that dynamic discharge enhances lifetime substantially compared with constant current discharge.

Specifically, for the same average current and voltage window, varying the dynamic discharge profile led to an increase of up to 38% in equivalent full cycles at end of life.

[1]: https://www.nature.com/articles/s41560-024-01675-8

reply
tecleandor
16 hours ago
[-]
But it could be very interesting for commercial or industrial use: commercial vehicles that are constantly driven and charged, power reserve batteries, tools...

And I guess that you could make devices with smaller batteries and fast charge, with less fear of wearing them early.

reply
flowerthoughts
15 hours ago
[-]
Note that LiFePO/LFP batteries used in cars and large installations are rated for 5,000+ cycles. They really are on another level compared to Li-Co phone batteries that top out at 1,000.
reply
WaltYoder
16 hours ago
[-]
For grid-level solar energy, we will need batteries that cycle at least 200 times per year. A system that requires replacing batteries every 5 years can't really be described as "renewable energy".
reply
gpm
16 hours ago
[-]
As long as "replace" includes "take the old batteries and turn them into raw materials for making new batteries" it definitely can.

Typical issues with old batteries are things like dendrite growth. There's nothing wrong with the materials that went into making the battery, they've just reshaped themselves into an unfortunate spiky structure.

reply
nomel
14 hours ago
[-]
Most EV map displayed 0% to 100% to something like physical 5% to 95%, or even more extreme, to help.
reply
gamblor956
17 hours ago
[-]
This is big news....if it can be refined into a scalable process enabling commercial production.

LI-S batteries have significantly more capacity than commercial Li-[x] batteries of the same weight, but the big weakness until now has been that they have terrible durability.

reply
ASalazarMX
17 hours ago
[-]
I'm kinda curios to know if they smell bad because of the sulfur. LiPo smells sweet, like bubblegum, when its electrolyte leaks. Would a Li-S electrolyte leak smell nice like fireworks, or weird like onion/garlic?
reply
antisthenes
18 hours ago
[-]
When to comes to batteries, you have to look at multiple factors.

Focusing on just 1, e.g. cycles doesn't give you the whole picture.

1. What is the capacity per $?

2. What is the capacity per kg?

3. What is the capacity per unit of volume?

4. Ease of disposal and recycling

5. Charge and discharge rates.

6. Safety.

7. Viable to produce commercially en masse?

There are just off the top of my head, and not necessarily in that order. The priority will vary depending on your use case.

reply
adrian_b
16 hours ago
[-]
There is no doubt about lithium-sulfur batteries being excellent and better than existing lithium-based batteries for conditions 1, 2, 4 and 7.

Depending on their structure, there may be problems to be solved about their safety and the resistance to corrosion of their components, which may limit the lifetime to lower values than expected from the number of cycles supported by the electrodes.

Here the sulfur is contained in some kind of borophosphate glass, which should not be easily flammable, so safety or corrosion problems are unlikely.

An essential component of this new battery is iodine, which has an active redox role, together with lithium and sulfur, iodine being an intermediary in the passing of electrons between lithium and sulfur. Iodine is a rather rare element. Fortunately its extraction from sea water is very cheap, but nonetheless the total amount of available iodine is quite limited, so hopefully the battery needs much less iodine than lithium and sulfur.

reply
gpm
16 hours ago
[-]
> Fortunately its extraction from sea water is very cheap, but nonetheless the total amount of available iodine is quite limited,

Huh? I don't know anything about this, but sea water is very plentiful so if that's where we get it how can the amount available be limited?

reply
adrian_b
21 minutes ago
[-]
Sea water is plentiful, but iodine is less that 60 milligrams per ton of water.

If the production of such batteries would require thousands of tons of iodine per year, that would require the processing of billions of tons of sea water per year, from which the iodine would be removed.

Moreover, I do not know the current prices, because in recent years the metal exchanges have become more and more secretive, but some years ago iodine was about 6 times more expensive than lithium, so if a large amount of it were required for such a battery it could raise its price.

Hopefully the amount of iodine used in such batteries would be low, because the amount of needed iodine is proportional with the power of the battery, but it should not depend on the amount of energy stored in the battery (because iodine is an intermediary in the electron flow, it determines the maximum current during charge and discharge, but it is not an endpoint for electrons, so it does not determine the amount of stored energy).

reply
cman1444
18 hours ago
[-]
To add a few other factors:

1. Performance in hot/cold environment

2. Safety can be broken down to chemical toxicity, and thermal stability (likelihood to catch on fire)

3. Ability to hold a full charge for extended periods of time (self discharge rate)

reply
cogman10
17 hours ago
[-]
One of the drawbacks to li-s is that it had terrible cycle life. This is interesting/exciting because they've found a technique to overcome a major disadvantage to a chemistry that ticks a lot of the other checkboxs you've listed.

The question now is manufacturing, is this something you can use at scale to make batteries.

reply
gpm
18 hours ago
[-]
This is research. You should be focusing on "what's new, and is it interesting" not "is the thing they made a good product".

That said, Li-S typically looks good with respect to potential cost if mass produced (cheap materials), and density metrics. The papers abstract has absurdly good things to say about charge rates. All-solid batteries are typically going to be very safe. So at a glance this research is at least in a very commercializable direction.

reply
ahartmetz
18 hours ago
[-]
>All-solid batteries are typically going to be very safe

Sulfur melts at 115 °C though, so when it overheats, it's not solid anymore. But then, it's apparently not just sulfur, but sulfur embedded in some other stuff, so who knows.

reply
adrian_b
16 hours ago
[-]
Here the sulfur is contained in some kind of borophosphate glass, which should have a significantly higher melting point.
reply
rcxdude
11 hours ago
[-]
Last I heard of Li-S batteries about 10 years ago, they were fantastic at energy density and safety, looked like they could be pretty cheap to make, but they only lasted about 10 charge cycles, so this is pretty exciting.
reply
Animats
17 hours ago
[-]
Right. All battery articles, to be taken seriously, need a little table with those numbers. There are many battery technologies which look good on some of those numbers but are so bad on others that the technology is useless.
reply
metalman
14 hours ago
[-]
this has a chart

https://www.batterypowertips.com/how-could-advances-in-solid...

and other variants are commonly used

reply
oakwhiz
18 hours ago
[-]
Exactly. For example the weight of a battery matters very little if used in a stationary application such as a BESS/UPS. But it's very important for transportation e.g. traction power
reply
Gibbon1
15 hours ago
[-]
One shouldn't discount the cost of just mass. Feels to me eventually products costs are based on manufacturing complexity, material costs, and energy. Material costs themselves are often energy per unit mass.
reply
antisthenes
16 hours ago
[-]
Oh, and another reason why high cycle count may not even be relevant - the battery may become technologically obsolete and non-viable to operate long before it reaches anywhere near the projected cycle count.

So very high cycle counts (e.g. anything above 4000 cycles ~ 10 years of use) should be taken with a very large grain of salt and may be completely irrelevant for practical uses, unless the application calls for multiple daily discharges (if that's the case, why not use a supercapacitor?)

reply
yapyap
18 hours ago
[-]
I hope the better batteries, when they genuinely are deemed to be better, are used in phones and stuff instead of using batteries that’ll go bad in a few years on purpose to drive up sales of new phones.

Even people who can deal with the slower speeds after a few years of owning a phone get driven crazy by having to charge it often, I’d say it’s a big driver if not the biggest to buy a new phone.

reply
hackingonempty
17 hours ago
[-]
We already have longer lasting chemistries, lithium iron phosphate. They are also an order of magnitude less likely to go into thermal runaway. However, they are seldom used probably because they are somewhat less energy dense and consumers prioritize size and runtime over battery life and safety. I don't think it is a ploy to drive up sales.
reply
chgs
3 hours ago
[-]
Consumers prefer larger tablets to phones, hence Apple abandoning the already large “mini” line after the iphone13
reply
nottorp
49 minutes ago
[-]
Apple have grown too big for their own good. The "mini" line sold a few million devices, but that's too little for the current Apple assholery.
reply
master-lincoln
17 hours ago
[-]
You could also just exchange the battery instead of getting a new phone. Of course producers made that more difficult over the years. By 2027 mobile phones sold in the EU are mandated to have a replaceable battery.
reply
AtlasBarfed
18 hours ago
[-]
In theory, a Li-S chemistry should be able to outperform Lithium Ion NCM chemistries by a factor of two or three.

Operating temperature range and cycle endurance were some primary barriers, and this seems promising, but ...

"The researchers suggest more work is required to improve the energy density and perhaps to find other materials to use for the mix to ensure a low-weight battery."

ok, nevermind.

reply
renox
3 hours ago
[-]
If it's written like this it must be quite low..

Note though that 'grid batteries' are a very important part for solar transition and they have very different requirement for weight and energy density than electric cars..

reply