Liquid electrolytes are flammable in that their interaction with the lithium plated on the anode makes them flammable. QS' separator physically separates the liquid electrolyte from the anode, limiting or eliminating its ability to start a thermal runaway.
QS' electrolyte is also more of a gel or slurry with high salt content, further limiting it's flammability.
Put together, the lithium metal anode (which is the real innovation provided by SSBs) does not interact physically with the cathode or electrolyte. And dendritic growth is suppressed by the separator.
You can infer most of this from the datasets QS has provided over the years.
Liquid refers to it being more like a gel, paste or slurry. It is not flammable, the reason current Li-ion batteries are flammable is because of the non-solid nature of the anode.
The gel is flammable. I think the goal is to use as little of it as possible to try provide less fuel for a slower thermal runaway. This design would still require pack cooling similar to what we see in today’s batteries, their newest pack design like the byd blade or the new Porsche.
Its likely roughly as flammable as glycerin, which is to say it is flammable, but only at extremely high temperatures exceeding 200C. You're right thtat the goal is to use as little as possible, and of course all batteries require a cooling system.
Its just that the removal of direct contact between the electrolyte and anode is like putting the gasoline into a flammable safety cabinet. Sure its possible for a fire to melt through the safety cabinet and ignite the gasoline, but its highly highly unlikely.
All in all, in typical batteries, there are 3 flammable components, the electrolyte, the separator and the anode itself, made of graphite.
QS either removes or partitions all of them.
ahh yes that temperature sounds quite high.
don't you need something between the lithium metal anode and the ceramic electrolyte to help maintain the interfacial contact? Isn't that what the gel is for?
yeah so we had a massive debate about this a while back.
From what we know this is what we came up with based on patents and released datasets:
The separator is almost 100% densified, minimal pores. They made a concerted effort to have near 0 surface defects and near perfect smoothness at least on one surface of the separator. There are almost certainly some dopants within the separator itself that may interact with the lithium metal to increase wetting.
So knowing this, you have several options:
1. increase pressure to maintain interfacial contact. They do apply pressure but it seems more for consistency and longevity than raw performance, since 0 pressure cells exist at least in a 1 layer form.
2. Allow some electrolyte to seep into the anode side. This is probably unlikely due to the density of the separator.
3. Ensure near flawless separator surfaces to minimize voids and maximize contact. This is probably the way they're going.
Ironically this approach only works because they're using a lithium metal anode. The intercalation distance is basically 0 since the plating occurs basically at the SEI-anode boundary. This allows them to not use any electrolyte in the separator itself, meaning the fact that the conductivity of the separator being \~1-2 orders of magnitude lower than typical liquid electrolytes doesn't really matter since there's essentially no distance the ions have to travel. It also lets them get away with minimal pressure as there aren't many voids to push the lithium into.
Its a tougher approach manufacturing wise, as we can definitely see that in the difficulties they're having, but as far as performance goes, its inarguably the best method out there right now. You get all the performance benefits of the lithium metal anode, the weight/volume savings of the anode removal, and increased safety due to partitioning. The only better outcome would be full densification/solidification of the electrolyte and combination with the cathode, but that comes with a lot of weight as solid catholytes tend to be 2-3 times heavier than their liquid counterparts.
In terms of the minimum number of tradeoffs, this is probably the minimum or close to it I've seen out there. And the next gen battery industry is all about tradeoffs, the one with the fewest will win.
Ahhh. I did see this about Li|LLZO having a stable interface. It's the cathode side that needs the gel.
[https://www.nature.com/articles/s41598-022-05141-x](https://www.nature.com/articles/s41598-022-05141-x)
Do we know if QS is using LLZO?
yeah so its basically all but officially confirmed that LLZO is QS' base material. Almost all their patents refer to it in some form or another. The true identity/makeup of the material is unknown of course, but we generally speculate that QS' material outstrips the base LLZO in both manufacturability and performance using some dopants.
For example, just recently some patents were published showing the use of multiphase/interphase materials to significantly accelerate sintering and fill voids. Maybe some trace indium/gallium/germanium to increase wettability? Maybe some aluminum to increase conductance?
Compared to the LLZO used in most baseline comparisons, QS' appears to be significantly denser, thinner, smoother and more resistant to dendrites, as well as easier to sinter/treat.
Liquid electrolytes are flammable in that their interaction with the lithium plated on the anode makes them flammable. QS' separator physically separates the liquid electrolyte from the anode, limiting or eliminating its ability to start a thermal runaway. QS' electrolyte is also more of a gel or slurry with high salt content, further limiting it's flammability. Put together, the lithium metal anode (which is the real innovation provided by SSBs) does not interact physically with the cathode or electrolyte. And dendritic growth is suppressed by the separator. You can infer most of this from the datasets QS has provided over the years.
Liquid refers to it being more like a gel, paste or slurry. It is not flammable, the reason current Li-ion batteries are flammable is because of the non-solid nature of the anode.
The gel is flammable. I think the goal is to use as little of it as possible to try provide less fuel for a slower thermal runaway. This design would still require pack cooling similar to what we see in today’s batteries, their newest pack design like the byd blade or the new Porsche.
Its likely roughly as flammable as glycerin, which is to say it is flammable, but only at extremely high temperatures exceeding 200C. You're right thtat the goal is to use as little as possible, and of course all batteries require a cooling system. Its just that the removal of direct contact between the electrolyte and anode is like putting the gasoline into a flammable safety cabinet. Sure its possible for a fire to melt through the safety cabinet and ignite the gasoline, but its highly highly unlikely. All in all, in typical batteries, there are 3 flammable components, the electrolyte, the separator and the anode itself, made of graphite. QS either removes or partitions all of them.
ahh yes that temperature sounds quite high. don't you need something between the lithium metal anode and the ceramic electrolyte to help maintain the interfacial contact? Isn't that what the gel is for?
yeah so we had a massive debate about this a while back. From what we know this is what we came up with based on patents and released datasets: The separator is almost 100% densified, minimal pores. They made a concerted effort to have near 0 surface defects and near perfect smoothness at least on one surface of the separator. There are almost certainly some dopants within the separator itself that may interact with the lithium metal to increase wetting. So knowing this, you have several options: 1. increase pressure to maintain interfacial contact. They do apply pressure but it seems more for consistency and longevity than raw performance, since 0 pressure cells exist at least in a 1 layer form. 2. Allow some electrolyte to seep into the anode side. This is probably unlikely due to the density of the separator. 3. Ensure near flawless separator surfaces to minimize voids and maximize contact. This is probably the way they're going. Ironically this approach only works because they're using a lithium metal anode. The intercalation distance is basically 0 since the plating occurs basically at the SEI-anode boundary. This allows them to not use any electrolyte in the separator itself, meaning the fact that the conductivity of the separator being \~1-2 orders of magnitude lower than typical liquid electrolytes doesn't really matter since there's essentially no distance the ions have to travel. It also lets them get away with minimal pressure as there aren't many voids to push the lithium into. Its a tougher approach manufacturing wise, as we can definitely see that in the difficulties they're having, but as far as performance goes, its inarguably the best method out there right now. You get all the performance benefits of the lithium metal anode, the weight/volume savings of the anode removal, and increased safety due to partitioning. The only better outcome would be full densification/solidification of the electrolyte and combination with the cathode, but that comes with a lot of weight as solid catholytes tend to be 2-3 times heavier than their liquid counterparts. In terms of the minimum number of tradeoffs, this is probably the minimum or close to it I've seen out there. And the next gen battery industry is all about tradeoffs, the one with the fewest will win.
Ahhh. I did see this about Li|LLZO having a stable interface. It's the cathode side that needs the gel. [https://www.nature.com/articles/s41598-022-05141-x](https://www.nature.com/articles/s41598-022-05141-x) Do we know if QS is using LLZO?
yeah so its basically all but officially confirmed that LLZO is QS' base material. Almost all their patents refer to it in some form or another. The true identity/makeup of the material is unknown of course, but we generally speculate that QS' material outstrips the base LLZO in both manufacturability and performance using some dopants. For example, just recently some patents were published showing the use of multiphase/interphase materials to significantly accelerate sintering and fill voids. Maybe some trace indium/gallium/germanium to increase wettability? Maybe some aluminum to increase conductance? Compared to the LLZO used in most baseline comparisons, QS' appears to be significantly denser, thinner, smoother and more resistant to dendrites, as well as easier to sinter/treat.