9 ms·

Stabilization of gamma sulfur at room temperature to use in Li-S batteries

33 points by Phithagoras 4y ago

jxf 4y ago
The "notorious polysulfide shuttling effect" mentioned in the first sentence of the abstract is a pretty big understatement. It's basically an automatic death sentence for Li-S batteries in commercial applications, so the fact that this paper claims to have _zero_ polysulfide formation is pretty remarkable. Short primer: The polysulfide shuttling effect is a phenomenon that can occur in lithium-sulfur batteries. It occurs when polysulfide ions, which are intermediates formed during the discharge and charging of the battery, are able to move from the cathode to the anode. This causes a decrease in the overall capacity of the battery. To prevent this from happening, a separator with a high ionic resistance is used to physically block the movement of the polysulfides, but this increases the bulk and form factor of the battery, which makes it less suitable for applications like phones and laptops.
AtlasBarfed 4y ago
Other sources say 4000 cycles in one year of testing and the battery is still going strong. Apparently they used some chemical vapor deposition to dope sulfur in a carbon mesh, and apparently gamma sulfur was created in the process, which was accidental, they're trying to determine why their process created it. Claim 3x the capacity of current lithium ion. That would be, what 600 wh/kg? 750? That seems unbelievable.
- _0w8t 4y ago
  The energy density is the reason Li-S batteries are researched in the first place. Other prototypes of Li-S batteries according to Wikipedia already archived 450 Wh/kg.
- jillesvangurp 4y ago
  4000 cycles is pretty impressive. Worth pointing out just how good that is: if you fully charge the battery every day of the year, that would mean close to 11 years of very intensive use. 4000 times a typical maximum range of 250 miles would mean driving a million miles. Some taxis get that kind of mileage of course. But most drivers would take quite a bit of time to get there. In short, if you are lucky enough to own a vehicle with such a battery, it needing replacement is not going to be an event that you should have to worry about for decades if you drive it normally. Which would mean doing about 14K miles per year; or about 71 years.
Animats 4y ago
It's nice to see a battery chemistry article that admits they're in the early stages of getting some new chemistry to work. The usual battery article is "we got this to happen in a test tube, huge world-changing breakthough Real Soon Now". Those have become tiresome. This article seems to have much less bullshit than most. Hope this one works.
- epgui 4y ago
  It's an academic paper in Nature, it's not CNBC.
  - roflc0ptic 4y ago
    more like university press
  - Animats 4y ago
    That means much less than it used to.
jojobas 4y ago
So they are claiming 800 mA-h per gram, which at 2.5V Li-S voltage gives about 7.2 megajoules per kilo, 1.5 the energy density of TNT. Somehow I don't want to be anywhere near a battery with that kind of energy density.
- actionfromafar 4y ago
  Gasoline has 40 megajoules per kilo.
- mjevans 4y ago
  A quick search on Google: petrol megajoules Petrol/gasoline 44-46 MJ/kg Diesel fuel 42-46 MJ/kg Crude oil 42-47 MJ/kg You're already near far denser volatile chemicals, even if it isn't you driving someone else is somewhere.
  - Schroedingersat 4y ago
    The key difference is the hydrocarbon "battery" has a volumetric energy density of around 12kJ/L if you include both halves where the sulfur one is still around 7MJ/L
    - Klinky 4y ago
      How are you calculating the volumetric energy density and the energy content of a liter of gasoline? 12kJ/L seems low.
      - Schroedingersat 4y ago
        In the context of comparing it to TnT or a Sulfur battery you need the oxygen too.
        Klinky 4y ago
        Perhaps I am misunderstanding, but that sounds almost like a calculation that applies to a vacuum, not a pressurized atmosphere with plenty of "free" oxygen? Perhaps that's the same for the TNT & battery, so maybe none of these calculations are directly applicable to real-world scenarios?
rkangel 4y ago
Note that this is not particularly new. This paper was published February 2022.

33 points by Phithagoras 4y ago

jxf 4y ago

The "notorious polysulfide shuttling effect" mentioned in the first sentence of the abstract is a pretty big understatement. It's basically an automatic death sentence for Li-S batteries in commercial applications, so the fact that this paper claims to have _zero_ polysulfide formation is pretty remarkable. Short primer: The polysulfide shuttling effect is a phenomenon that can occur in lithium-sulfur batteries. It occurs when polysulfide ions, which are intermediates formed during the discharge and charging of the battery, are able to move from the cathode to the anode. This causes a decrease in the overall capacity of the battery. To prevent this from happening, a separator with a high ionic resistance is used to physically block the movement of the polysulfides, but this increases the bulk and form factor of the battery, which makes it less suitable for applications like phones and laptops.

AtlasBarfed 4y ago

Other sources say 4000 cycles in one year of testing and the battery is still going strong. Apparently they used some chemical vapor deposition to dope sulfur in a carbon mesh, and apparently gamma sulfur was created in the process, which was accidental, they're trying to determine why their process created it. Claim 3x the capacity of current lithium ion. That would be, what 600 wh/kg? 750? That seems unbelievable.

_0w8t 4y ago
The energy density is the reason Li-S batteries are researched in the first place. Other prototypes of Li-S batteries according to Wikipedia already archived 450 Wh/kg.
jillesvangurp 4y ago
4000 cycles is pretty impressive. Worth pointing out just how good that is: if you fully charge the battery every day of the year, that would mean close to 11 years of very intensive use. 4000 times a typical maximum range of 250 miles would mean driving a million miles. Some taxis get that kind of mileage of course. But most drivers would take quite a bit of time to get there. In short, if you are lucky enough to own a vehicle with such a battery, it needing replacement is not going to be an event that you should have to worry about for decades if you drive it normally. Which would mean doing about 14K miles per year; or about 71 years.

Animats 4y ago

It's nice to see a battery chemistry article that admits they're in the early stages of getting some new chemistry to work. The usual battery article is "we got this to happen in a test tube, huge world-changing breakthough Real Soon Now". Those have become tiresome. This article seems to have much less bullshit than most. Hope this one works.

epgui 4y ago
It's an academic paper in Nature, it's not CNBC.
- roflc0ptic 4y ago
  more like university press
- Animats 4y ago
  That means much less than it used to.

jojobas 4y ago

So they are claiming 800 mA-h per gram, which at 2.5V Li-S voltage gives about 7.2 megajoules per kilo, 1.5 the energy density of TNT. Somehow I don't want to be anywhere near a battery with that kind of energy density.

actionfromafar 4y ago
Gasoline has 40 megajoules per kilo.
mjevans 4y ago
A quick search on Google: petrol megajoules Petrol/gasoline 44-46 MJ/kg Diesel fuel 42-46 MJ/kg Crude oil 42-47 MJ/kg You're already near far denser volatile chemicals, even if it isn't you driving someone else is somewhere.
- Schroedingersat 4y ago
  The key difference is the hydrocarbon "battery" has a volumetric energy density of around 12kJ/L if you include both halves where the sulfur one is still around 7MJ/L
  - Klinky 4y ago
    How are you calculating the volumetric energy density and the energy content of a liter of gasoline? 12kJ/L seems low.
    - Schroedingersat 4y ago
      In the context of comparing it to TnT or a Sulfur battery you need the oxygen too.
      - Klinky 4y ago
        Perhaps I am misunderstanding, but that sounds almost like a calculation that applies to a vacuum, not a pressurized atmosphere with plenty of "free" oxygen? Perhaps that's the same for the TNT & battery, so maybe none of these calculations are directly applicable to real-world scenarios?

rkangel 4y ago

Note that this is not particularly new. This paper was published February 2022.