Battery Revolution Clubhouse Recording - Thermal Management

0:00Transcript

0:00So this is a pet topic for myself and my co-founder, Gigi, who's here on stage joining us today. And because we predominantly deal with thermal management system at Robles, which is the start that I'm running. So it's very exciting today to actually talk about this topic because we've been having a lot of co-fired speakers. And I thought, hey, why don't I share something about what I know in this space? So, yeah, so that would be interesting to hear our thoughts, experiences on this topic as well. And before we jump deep dive into the topic, just some regular housekeeping rules for the room. So this room lasts about one and a half hours. And if you want to join us on stage, feel free to raise your hand and we'll let you up on stage. And if you're up on stage, you want to let us know that you wish to talk. Just feel free to tap on your mic twice like so. And if you wish to clap, just flutter your mic like so.

1:16Great. So this session will be recorded on batteryinsiders.com for podcast. So if you missed the session or, you know, you have to jump off halfway during the session, feel free to go back to batteryinsiders.com to check it out. And I'll pass on to Simon, my co-host, to see if there's anything to add. Simon, please. Thank you, Catherine. Yeah. Very excited again for today's session with our truly, I'm Catherine. So I'm very excited to actually hear more from, also hear more from your expertise. As Catherine already mentioned, we're doing this session every week, every Saturday. Now it's already the 18th week, which is incredible how quick the time flies by. And I'm very excited that we have some familiar faces also in the audience. And I'm sure there are many more people also maybe want to join later on stage and contribute their questions and insights. Yeah. Maybe just one thing, as Catherine mentioned. So we have the sessions online. We now have also had some support.

2:14So we released a few more episodes from past discussions on batteryinsiders. You can also find on Spotify and Apple Podcasts, et cetera. And there are also going to be some more, including the battery den. We're hopefully going to release over this weekend and later by Monday. And then, yeah, if you want to listen back or if you want to share any of your, you know, any of these sessions with your friends, for free to do so as well. And then I think with any further ado, I'm very excited to introduce Catherine and Giggy for today's session. Very excited to hear from them on thermal management. And, yeah, let you take it away. Thanks so much, Simon. It's interesting how we've been hosting this for 18 sessions. And this is the first time that we are running as co-host and fire starter speaker. So I'm excited to see how this turns out. But I just wanted to share how, why is this topic is important? And maybe you can take on from the technical side of things.

3:10So the reason why thermal management is an important topic for batteries especially is because there are major concerns with lithium-ion batteries especially. And the failures of lithium-ion batteries are typically a result of temperature rise and temperature non-uniformity. And we're not just looking at very extreme operating conditions like fast charging, fast discharging or extreme ambient conditions. We are looking at normal operating conditions of a battery. And that could also cause significant buildup of heat in a battery pack itself, which is why a lot of EV manufacturers and OEMs, when they're making the battery pack, they will consider thermal management into their batteries. So case in point is Tesla. They do design thermal management system into their battery packs. And there are a lot of, you know, different types of thermal management system, which we'll jump in in a second. But beyond EVs, thermal management systems are really important for stationary storage. So if we're looking at stationary storage, be it residential, those container ones.

4:22These thermal management is also really important at a battery level, but also at a whole system level. So at our company, we presumably deal with the battery level thermal management system. And by battery level, I mean thermal management systems that's incorporated into the batteries itself. So there are different types of cooling. There's active cooling. There is passive cooling. And there's a combination of both. And I'll jump more, dive more into that later in a second. And I just wanted to kind of highlight why this topic is actually really important when we are talking about batteries, because we're just looking at safety issues. We're not just looking at overheating issues. So with overheating, what happens is the batteries can tend to cause thermal runaways. When you have a particular cell that's overheating, that could cause a thermal runaway event in the whole battery pack. And when there's a significant buildup of heat in the battery pack, there will be life degradation issues. And on top of that, also uniformity, non-uniformity within the battery pack itself.

5:40So all these issues would basically amount to three things. One is safety. The second is longevity. And the third is the usable capacity of the batteries at any one point in time, depending on whether you're doing it for high power usage or more extreme use cases. So this is why a lot of OEMs will have to look into how to develop battery thermal management system into their vehicles and also for stationary storage. And this is why this topic is also important and very dear to our hearts. And I will let Gigi jump more into the technical aspect of the active cooling and the passive cooling system. And I just wanted to give a brief outline here as to why this topic is important and something that we should be looking at as well. So Gigi, I'll pass the mic on to you. Yeah, sure. Thank you, Catherine. A little bit about myself. I'm Gigi, and I'm the co-founder and CTO of Rofless. And my main role was mainly on the heat management for battery.

6:58So just like what Catherine mentioned earlier about if the battery cell have some sort of like thermal runway issue, that could potentially be a huge hazard. So for example, such as like for many of the Chinese EV that and one of it is just happened recently from Xiaopeng car manufacturer. So Xiaopeng car just catch on fire in Shanghai, I believe. And the reason was because the battery just sits underneath a direct sunlight and it doesn't have a good quality on the cell. But mostly once the cell exploded or overheat, it just dissipates the heat all across the entire pack. And which basically makes your battery pack become a bump that it's just underneath your seat. So that's the main issue with how important the thermal management is. And what I'm doing mostly is to develop a material. We call it phase change material. So basically it's a material that will wrap all around the battery cell and prevent the heat from building up from each individual battery cell.

8:21So there are a couple of different methods that we can use to achieve the battery cooling. So the most typical one is the liquid tubing done by Tesla. So the structure is like a tube that looks like a snake and it will be wrapped all around the battery cell. So those kind of snake shaped tube, it will have a liquid or a coolant running into it and take the heat away from it. The main issue with that was the temperature distribution could be highly non-equal. So the reason was because when the inlet water or the liquid is flowing through, the heat will be taken away from the liquid, but also the liquid will be heated up. So at the end of the cooling system, the liquid may have quite a different temperature compared to the inlet. So that's the main issue. And why the uniformity of temperature matters a lot with battery was because the battery life is highly depending on the consistency of the battery cell.

9:36So there is a cliche or a phrase saying that the strength of a chain depends on the weakest zone in the chain. So that's what happens with the battery. So imagine like there are a couple battery cells that it's not performing as strong as the others. Then once those cells die out, then the whole pack will die out. And this is why it's important for the uniformity of the design. And this is also like the weakest point from Tesla. So to solve this problem, there are also many other solutions. So one of the most, let's say like the most expensive, but also the most effective one, it's called immersion cooling. So when I do it, it will submerge all the battery cells inside a cooling liquid. And because the liquid does not have an external protection, such as like a copper tube or aluminum tube that's preventing the liquid from leaking out. So the liquid will just directly contact the battery cell. So in this case, it can be the most effective way to take the heat directly out from the battery cell.

10:56And also if the battery catch on fire, the liquid can just directly pull off the fire to make sure the least amount of damage will be spread around the battery pack. But like I said before, those liquid has to be directly contact the cell, which means the entire casing has to be fully waterproof. And also the liquid itself has to be dioelectric. So dioelectric means that the liquid cannot conduct electricity. And that's one of the hardest part for this liquid. So couple of manufacturer making it such as like 3M, we call it NOVAC. So NOVAC is their dioelectric fluid typically used for industrial computer. So for those computer that it's called supercomputer or those kind of like pretty high performance one, they have to be in the data center, which will build up the heat directly. So those 3M NOVAC fluid is directly used for that kind of application. But once we put it into the battery, it's also quite effective. But the problem is the cost.

12:13So imagine the current Model 3, I believe it's like 30K USD. Correct me if I'm wrong. But if we are using that kind of technology, the battery cost itself will be almost twice of the current cost. And imagine like battery typically costs around 30% of the total vehicle cost. So that will give you another like, let's say 9K to 10K of the cost. So it will build up the total vehicle cost to like 40 to 50K. And that is quite a big concern for most electric vehicle applications. So that's why this kind of immersion technology may not be the most practical one. But also the more important point is the reliability. So if everybody is driving a conventional gasoline vehicle, it's quite direct that every couple years or let's say every like thousand miles, you have to refill your coolant. And like cooling liquid check, it's quite typical for like engine inspection. And the reason you have to refill the coolant is because there are always leakage from the cooling system no matter what.

13:35So that's called a reliability. And let's say if the if the cooling is widespread around the whole system, there is a much higher possibility that the cooling will leak out. And the more coolant leak out, the less reliability you got for the vehicle. So this is exactly the same issue happening for battery pack design. When you have direct liquid coolant submerge the whole system, it tends to leak out quite easily no matter how good you are with your enclosure. So this is another big concern for maintenance issue. So after all this, I'll say people will ask like, so if the active cooling using liquid is so expensive and unreliable, then why not we go for some other smarter ideas? So in fact, there are many good ideas that is used for battery cooling. So some of the innovative points such as what GM was using mostly is that they are using a flat cell compared to a cylindrical cell. So those flat shape cell we call a pouch cell.

14:52And those pouch cell are basically a rectangular shape. It's like a sheet of paper, but with a much thicker height. And those kind of cells are designed in a way that they have much greater area for heat dissipation. So imagine if you have something that can be contacted more easily, then the heat can be taken out much easier. So that's how GM was doing it. And also it's followed by a lot of European automotive companies such as BMW, Mercedes and Porsche. So we may know that there is a latest model from Porsche called Taycan. So that's their first electric production model. And even like the absolute performance is not better than Tesla, but Porsche Taycan has a much greater reliability and durability. So the reason was because like mainly on the battery point where they are having a better heat distribution. So remember Elon Musk claimed that also our Roadster 2.0, we can accelerate from 0 to 60 in 1.8 seconds or 1.9 seconds. But what Elon Musk was saying is that they can only be run once.

16:23So imagine if you want to try this 10 times, then the result at the 10th trial is going to be much worse than the first trial. And also another issue is that if you have a model, as you may notice, there are four modes. Like economy mode, normal mode, sport mode and race mode. So at the performance mode, especially the last one, when you switch it, the system will say, oh, so we start to heat up your battery. So you have to wait for like, let's say 25 minutes before you can do like those kind of models as super performance. So imagine if you are at a drag race and somebody like a rude guy or somebody with a muscle car and they yell at you like, oh, you got an electric vehicle and I don't think you can outbid me. And you say like, oh, for sure I can. And that started drag race. But at the beginning of the drag race, you said, oh, wait for me for 25 minutes.

17:25I need to heat my car up. That's kind of embarrassing. But that's how the current electric vehicle technologies. But what Porsche are taken is doing really good. It's that for the first to the 10th trial, they can they can consist of a similar performance. And even like there is typically no difference between like every of their trial on the performance. So how we say it's a rated performance, not the absolute like ideal performance. So, yeah, a little bit far from it. But basically, that's that's the main difference between if you can actually do the battery thermal system or the thermal dissipation wheel. Yeah, I think I will pause here and see if there is any question. Thank you so much, Catherine and Gigi. I think it's a really insightful overview of a topic where I have to admit, I think there's many things I can still learn. It's very exciting for you to share your insights. And now maybe it's a good time also for people from the audience to come in.

18:32I know there's some brilliant people here or some people joined us earlier and also just joined recently who have experience in this space. Maybe also some interesting questions. So, yeah, just an open invitation. And maybe for everyone who's new to this room, we have these rooms every week related to a battery topic. And this week it's on thermal management. Yeah, maybe till anybody else comes up. I have a question. So you mentioned like, you know, a few different companies have been different approaches, you know, Tesla, Porsche and others. So I'm kind of wondering, you know, I mean, there's like different, as you mentioned, also different reasons why you would do this, right? Like one is performance. Another one is safety. Can you see like any trends right now from like these different systems which are used? I mean, you mentioned, you know, passive cooling, there's, you know, water cooling, different like, you know, liquid cooling systems. So I'm just wondering how much innovation can you like, you know, foresee in the sector?

19:24I mean, is it like, you know, that we haven't really found anything yet, which is going to be last? Like, do you think for example, the technology developing could like, you know, outpace all of them? Or they're going to be different technologies for different use cases in the future? Yeah. Speaking of the innovation part, let's say if we can go back to the basic elements of why we need those cooling system. So it's mostly for, let's say first the battery life, but also more importantly the safety. So if we can have one system that resolves both issues, that's where the innovation comes from. So speaking of that, like we do mention like liquid cooling, but most liquid cooling, they only solve the heating issue. But let's say if the battery start to build up the heat or start to getting on fire, then those systems cannot offer much help. And let's go another way around when people talk about the safety or the battery protection.

20:34So those typical case are used by NASA or by a lot of rocket or marine battery. So how we are talking here, it's let's say for those UAV or military use or space use, those batteries, they care mostly about the battery does not explode inside the rocket. So it doesn't like cost a hundred million dollars things to be broken because of one single component failure. So in that case, they wrap the battery heavily by non-explosive material. And those material is like doing a good job for making the battery safe. And also it doesn't like cause any severe issue around the system. But the problem is that it doesn't really take the heat away from the battery. So, but it doesn't matter for those applications because mostly there is no heat associated with like rocket or space when you are in the space area. Yeah. So let's go back to like the innovative part. So before then I was talking about the NOVAC, the solar immersion cooling idea, which is one of the examples.

21:56But I can do a little bit introduction about what we are doing here. So we are also trying to come up with an innovative idea for battery cooling. So our understanding is that typical active cooling has less reliability. So we were thinking if we can use a passive cooling idea, which means there is no mechanical control or there's no like active engagement between the vehicle and the battery cooling. But also you can make sure the battery temperature is low enough. So then we figure out like, like the, it's similar to the immersion cooling where you have direct contact with the battery. So we were using a wax like material. So basically it's a form of wax that we submerge the battery cell inside the wax. So wax is more solidified and also the most greatest feature for the wax is their latent heat. So for those non-technical person, latent heat is a amount of heat you can store inside a specific material. And how is stored?

23:14It's that you convert it from one state to the other. So imagine if you have a cube of ice, then for the ice to melt down, it has latent heat. So once the ice melts from an ice cube to water, the heat is absorbed. It's called latent heat. So the latent heat for wax is quite large. And what we are doing here is we are using that feature to store the heat from the battery. But the most innovative part about our material, we call it the phase change material, was that we try to increase the thermal conductivity of the material and also the flushing point. So the first one, the thermal conductivity, is that it can take the heat much faster compared to conventional wax. So for our current result, we have like 10 times more thermal conductivity compared to conventional wax. So in this case, it can dissipate the heat much faster. And that could be quite a big improvement for the uniform heat temperature distribution.

24:29But also the other point is the flushing point. And that's like the most significant issue associated with battery thermal runway. So when a battery got penetrated or if a battery got overcharged, it will start to explode. So the temperature around the battery cell will be mostly higher than 600 degrees. And if there's actually fire coming up, it can easily reach over 1000 degrees Celsius. And in that case, if the flashing point for the surrounding material is too low, let's say if that's only like 100 degrees Celsius, then those material can be easily catch on fire and act as another flammable assistant to the battery explosion. So what we are doing here is we add other material into conventional wax to increase the flushing point, which is roughly 100 degrees Celsius higher than most conventional wax. So in that case, it can protect the battery cell from catching fire. And mostly it's about like suppressing the heat generating from the battery cell. So that's the innovative part I want to share now.

25:57So I think I'll get back to Simon for other introduction. Simon Wittgenstein Thank you so much. You know, really interesting. And I'm curious also to talk about it further later on, you know, especially for like stationary use, right, where I've been talking to other like, you know, stationary battery providers have been telling me that I'm actually temperature control is a big issue because there isn't any. For a lot of the systems I've been using, it's all passive. And this can actually have quite a big impact on degradation over time and predicting degradation and like, you know, these kinds of things have been quite tricky for them. But before I kind of keep asking, I would love to welcome also Maggie. Thank you so much for joining us. Maggie Thank you so much for joining us. Maggie Good morning, guys. Simon Wittgenstein Good morning. Good to see you. Do you have any thoughts or questions on this topic? Maggie Yeah, this was great. You know, unfortunately, coming from the manufacturing world, the the pack and the management system, I haven't really looked into.

26:51So this was really, really great. And I learned I learned a lot. Curious, though, in from an economic or supplier supply chain question, are most manufacturers doing all of this in house? Are they looking out of house to, you know, solutions like you guys are providing? Typically, I've seen everybody kind of go in house and that's good for cost. But also, you don't get yourself exposed to potentially new innovations that could further better your product. Hi, Maggie. Yeah, thank you for the question. So, basically, it depends on the level of complexity of that specific component. So, most manufacturers, automotive manufacturers to be more specific, they want to build the entire battery system in house. But the entire battery pack consists of like multiple major components. So, let's say, couple components they absolutely want to build by themselves. First, it's BMS, because that's the main control and so-called the data center for the battery. And the second one is the battery sale. So, but battery sale, it's like really expensive and consume most of the cost for the pack.

28:16So, if they can build it by themselves, then it's going to be the greatest cost reduction. But again, like investing on battery sale manufacturing is quite, quite expensive. So, what Tesla is doing is they work with Panasonic to build up gigafactory. But other European company like Volkswagen and Volvo, they are investing in a sale company called the battery. A sale company called Northvolt in Europe. So, in that case, they can have their local sale supplying and control the cost. And other smaller automotive manufacturers, they will choose to work with the sale supplier, such as famous Chinese sale CATL. And also, it depends on the region. So, let's say for Tesla, they don't use the sale produced in US. So, they set up a Shanghai manufacturing center. And they were working with LG on this case to produce their sale for the Chinese market. So, it really depends on the region and also like the production capability. But other than BMS and sale, the other components is highly subjected to whether they think build it themselves, it's going to be cheaper.

29:45So, let's say if there are like epoxy or wax or other kind of glue or adhesive material, they don't typically build that. So, they will purchase it from chemical company and to integrate that into their system. But for most of the mechanical components, they will choose to make it themselves because that's where most of the cost come from and where they want to control the cost. And lastly, it's about the integration and testing. So, mostly on the battery pack assembly or integration with the control system. So, at this kind of higher level, for sure they want to do it by themselves. And there are two main reasons. First, it's the cost reduction. And the second, it's the quality control. So, that's a lot about like their system reliability and also their core technology if they don't want to leak out. But other than that, if they consider buying it from an external supplier, it's going to reduce costs. And also, if that's going to reduce their risk, then for sure they are going to do that.

31:04Thank you. That was informative. I didn't even think of the regional aspects of that. Thanks, Maggie. Just to jump in really quickly as well. It also has a lot of information that we have to do with the cost reduction. It also pretty much depends on the applications that we are looking at. So, actually for stationary storage, back to what Simon mentioned earlier, there are a lot of queries or use cases where a thermal management system is needed. And for these suppliers who are, you know, making the energy storage systems, they do have, I think that the supply chain is probably more different from the OEMs, where the OEMs want to secure things from the cell level all the way to the pack design, etc. So, the stationary storage have a different approach. So, they are more used to kind of acquiring different types of materials and from different suppliers to better the system. So, I think that's a big difference between the applications and just wanted to drop in there for further discussion as well, just in case Simon wants to pick up on that later on.

32:23Moving on to Milo's. Milo's just joined us on stage. So, Milo's, what are your thoughts to this? I just joined you, so I don't have any major question for now. A little bit later I will ask the question. And also, I'm driving. I don't want to disturb you. But I will ask the question later. Okay, great. Thanks, Milo's. Sorry, Maggie, do you have something to add earlier? I might have cut you off too soon. Oh, no. I was going to agree with you on the stationary. I think there's so many opportunities and the cost of a stationary system would beg for a better solution. Obviously, that could be more costly and or different just because of the cost, initial capital cost to procure and put that in versus a vehicle for a person, for commercial or for personal use. Right. Yeah, thanks for that. Oh, did I, did I run him off? Oh, no. I'm not sure. I think probably a bad connection or something.

33:27Hopefully he joins soon. Sorry, Simon, did I cut you off? Oh, good. No, I just thought I maybe can go a bit further on the stationary point because I find something, you know, I think people talk a lot about the cooling for, oh, here, yeah. Welcome back. People talk a lot about the cooling systems, storm management systems for mobile applications, but I think I feel like there's less talk about it for stationary. Now, we'll just be curious if you maybe can also provide a bit of an overview or some insights. What are like the systems which I use at the moment because I haven't really heard much about them and I don't know many different systems for that. Right. Thanks for that. So, okay, if we look at stationary storage, there are a lot of different use case or application for that. So there are some that are used with very high power for automatic frequency control to the grid. And that typically we're looking at 4C discharge, which by batteries, that means you have fully discharging a one megawatt hour system in like 15 minutes or so.

34:34That has a lot of power and a lot of heat generated as well. And we, and a lot of the typical stationary storage, they have lower power applications, so they're more like less C rates, something, you know, something about 0.5 C or so. So these will not have too much of a heat issue, but they have longevity issues. A lot of them need to last about 10, 15 years, et cetera. And the warranty needs to be that long as well. So the applications will determine what kind of thermal management system needs to be used. Having said that, a lot of the stationary storage are also come from recycled cells, which second life cells, which I think Maggie, you'll be talking about that in a few weeks time on second life. And with second life cells, you have to make sure they are a lot more stable, typically, than the first life cells. So you have to make sure that they're able to perform under the optimum temperature in order to kind of increase the efficacy of the whole system and for safety reasons as well.

35:44So both passive and active cooling have been used in stationary storage. If we're looking at the higher C-rate ones, those for automatic frequency control, a lot of them tend to combine both. So they do cell level thermal management system all the way up to the whole system. So air conditioning, they have to simulate the heat distribution, et cetera. And also couple that with the cooling system as well. And for those with lower C-rate, typically they will opt for whatever, whichever is easiest for their system. And a lot of the times we're looking at just air cooling or air conditioning. But there are many different types of TMS, the measurement system that can be used. And for stationary, because they don't have size constraints, they are a lot more open to different liquid, be it strong air conditioner, et cetera. For mobile applications like those in the two wheelers, the scooters, those that have size constraints, they typically have a stricter requirement as to what type of thermal management system can be used to fit into the vehicle.

36:58But for stationary storage, if we look at those with high C-rate, they will just kind of couple active with passive, whatever works to ensure the safety and the longevity issues. So I hope that answers your question. Thanks, Katherine. Yeah, maybe also one thing just to invite other people as well, because I know there's some people in the audience who have much more knowledge about this too. It's about charging, right? I think, you know, we've spoke now about, you know, acceleration, these kind of things, of course, also creating heat. But I think also charging is a big aspect for cooling as well. And if you want to do super fast charging and things, this is an invitation for people like Stefan and others in the audience, if you'd like to come up. We'd be also interested in your thoughts on this as well. But maybe we can have Ali jump in for now. Hi, Ali, good to see you. Yeah, thank you very much. I'm really sorry, because I'm right now waiting for a TV interview.

37:52Just give me 10 minutes. I will be back soon. Amazing. We won't stop you from doing your TV interview. But we are looking forward to have you on later and wish you a good interview till then. Yeah, I really love to talk with you guys. Just give me 10 minutes. No problem whatsoever. We will have to 10 minutes, no problem. If we find out what he's on, we can watch. It's a good thing. Live television. Yeah. I guess he's preparing, which is good. And then we can hear from him right afterwards. Yeah, maybe Stefan or someone else, if you'd like to come on. Because I would be quite curious also. But you can also, of course, ask Catherine and others as well. But I would be quite curious, what's the impact on the charging speeds, right? I mean, I had a recent conversation with Hans-Peter, who I think is not in here right now. But there's been an imperial session. There's been a speaker there.

38:46And we have been, you know, I've been talking with others as well. Like, you know, what are the limitations, limiting factors right now for fast charging? And like, you know, go beyond the speeds, the kilowatts, what we can see today was, you know, 50 kilowatts, et cetera. So I'd be curious maybe if you also have some thoughts on this, Catherine, and Gigi when he comes back on, you know, what's needed to push us beyond the 350 kilowatts charging if you want to go that way. Right. I'll jump in, in case Gigi didn't hear the question. So, I'm not exactly sure from the charging stations perspective, and would love to hear, you know, anyone in the audience, feel free to jump in here. But from the battery perspective, firstly, pretty much depends on the type of cells that we're using and what's the maximum discharge and charge rates that's available. So there are some cells that are really power type cells and they really do allow for like 6C or so.

39:53And that is pretty much the limiting factor of how powerful you can charge your battery or discharge your battery. What thermal measurement system does is to allow the batteries to be able to do that, to be able to perform at its optimum and its maximum potential, if we could call it that way. And so, the thermal measurement system should be able to provide a very conducive environment by taking away the excess heat that's been generated with all the battery cells being packed together, you know, in a battery pack, to power a particular vehicle or for stationary storage usage. So, the question is, I think, is more about on the cell level, what can be, you know, what is the maximum discharge that's allowable by each cell? Obviously, depending on what kind of cells we are looking at, we have actually dealt with cells that can go up to 6C continuous, 13C instantaneous. So, it pretty much depends on the cell and coupled with thermal measurement system, that's to be able to allow the cell to use it as maximum.

41:11And Gigi, would you like to jump in here? I'm not sure whether you are able to hear the question earlier. Yeah. Yeah. Yeah. So, speaking of like, let's say fast charging, why is it related to thermal management? So, one of the aspects is just like what Catherine was talking about, it depends on the cell property, and also it depends on the heat buildup. But, the interesting part about the fast charging is that it doesn't just be cooled down by the system, but also it has to be heated up. So, the reason why we say thermal management for battery, but we doesn't say like cooling technology or cooling for battery, is because thermal management has to both heat up the battery or cool down the battery. So, in fact, actually for battery cell failure, part of it is coming from overheat, but another great portion is coming from low temperature. And battery cell could die much faster if the temperature is lower than let's say 10 degree Celsius or 0 degree Celsius.

42:33So, why does it matter for fast charging? Well, that was mainly because like, if you want to input a significantly higher energy to a battery cell, you need to get the battery cell into a certain working temperature. And that working temperature is typically above 35, so sometimes it's like 40 to 45. And the reason to, I would say like one of the metaphors to understand this, is that imagine if you want to do a sprint or a like extreme sport, then you have to warm up your body first before you move on to that. Let's say if you just wake up from bed and you want to go for a sprint run, then it could potentially damage your body. And that is exactly the same principle for the battery cell. And battery cell property to dip more into a technical side, there is something called an internal resistance. So that's what we call the IR. And imagine if the IR is higher than that means there are more resistance for the battery cell to either take the energy in or output the energy out.

43:51And the battery cell has a lower IR, the lower resistance when it has a higher temperature. So the internal resistance for the battery cell at, let's say 40 to 45 degrees Celsius, it's much less than when the battery cell stays at 10 degrees Celsius or at 20 degrees Celsius. So that is one of the really tricky factors that if you want to do fast charging, you need to get the battery cell at that certain temperature level in order to reduce the resistance of the battery cell to achieve the fast charging. But you don't want to make the battery cell going too high of the temperature, which could potentially cause explosion. So that kind of typical factor in control is quite crucial for the battery pack design. It's not just about the battery cell itself, but it's more about how you integrate the whole system together. And relative of this, I can give another example for charging. So I think one of the video online is quite popular in recent days was that a Tesla can just sit in a outside snow condition.

45:15And even the ice is covering the whole vehicle. It can heat up the vehicle itself and get all the ice meltdown. So this is one of a, I'll say quite impressive feature because most like internal combustion engine, you have to scrap out the ice from your windshield and a car body manually. And it take like 30 minutes or an hour to do that. And mostly you'll get yourself late from work or it can be quite a hazard to do so. But what Tesla can do is it can actually start off the battery for heat up the entire vehicle and even heat up the battery itself. And the reason for doing that was because especially at a really cold weather, then the battery cell has to be heated up to its working temperature. Let's say mostly it's above 10 degrees Celsius. So after that temperature range, then you can start to charge your battery. So charging a battery, it's more related to getting the temperature right instead of like just cool down the battery itself.

46:30Yeah. So that's my comment on the battery fast charging and also the temperature control associated with it. Thank you very much, Gigi. And I think that this is a really interesting and important point you made, which was really like, you know, that obvious for me either. That you also have these issues, right? With the cooling. I mean, of course we have seen this in the past and there's some fun stories like what you mentioned, but also like resistive heating and kind of shortening the batteries to kind of heat them up and things. I've heard of like interesting approaches by different companies. But yeah, I think that's a really interesting point, you know, to say it's not just the cooling, but also the heating is also quite important. Lynn, would you like to go next? Welcome. Lynn, are you with us? Thank you. Good morning from Chicago. I'm very interested in this conversation as a non-engineer, non-chemist. I'm an economist. I work in market design and transactive energy.

47:36And so my interest in batteries is in their capability to solve the intertemporal mismatch between supply and demand. And so usually we think of that as arbitrage, but I think, you know, batteries have so many other capabilities for doing, you know, voltage regulation, frequency regulation, etc. So my question regarding the thermal management is, you know, one of the challenges from a market design perspective is getting kind of acceptance to use batteries in this bidirectional way, the vehicle to grid challenge. And both from a warranty perspective and from a just grid architecture perspective. My question is, does doing that V2G bidirectional charge discharge that you would need for a transactive system, what are the implications of thermal management for that? Yeah. Hi, Lynn. Thank you for your question. And I think I will try to answer it with like a more general knowledge kind of point of view. So it will be much easier to understand. Let's say for automotive use and for typical energy storage use, those batteries are designed quite differently.

49:10And if we are speaking of, let's say, how thermal management affect it from the commercial standpoint, it's mostly how long you can use that battery. So we call it the battery lifetime. So imagine if you invest in a energy storage system, then that become your asset. So you want to make it to be used as long as possible. So there are many factors that affecting the battery lifetime. So the top factor is about a battery property itself. But imagine if we are all using a tier one battery cell, then the second property comes from if you can control the battery temperature in a more desired way. So in that case, it's that if a battery stay too hot or stay too cold, it's going to affect the lifetime a lot more than if you keep a battery temperature stay at a consistent scenario. So that's typically what thermal management system do for the battery life and also on a commercial purpose. So let's go deeper into like this aspect about if you are talking about V2G or just the energy storage condition.

50:38And how thermal management play different role, it's mostly on the operating condition or we call it the drive condition. So for vehicle, because the drive condition is mostly you have to stop at the traffic light and go. And also sometimes vehicle will go through highway with a constant speed. So those kind of driving cycle, it's highly different from energy storage. And one of the other more typical difference is how much energy you use from the battery. So imagine if your battery have 100% of energy, then every time you use the battery, it can depend on how many of the energy you want to use. So the life of the battery can be much higher if you only use like 60% of your battery compared to using 100% of your battery. And that could be another great factor affecting the battery life. And we call that the using condition or the operating condition of the battery, which basically means that how you use your battery can be a dramatic effect on the battery life.

51:59So back to the thermal management part. The thermal management is mostly to control the temperature range of the battery in order to achieve the safety and also the battery life extension. And for the energy storage, it mostly depends on the purpose. So we may know like you just mentioned one of the application is called auto frequency control AFC. So AFC, the purpose for it, it's like a, a transition or a intermediate energy delivery station where you get the energy from the, the wall or the grid, and then you can adjust it to make sure the output to the entire system is stable enough. So in the entire day, there is a peak usage and a low usage. And what the AFC does is that it will control the energy distribution across the peak and the low usage to make sure the energy or electricity supply is quite stable. So on a commercial side, how we can manage the battery without overheating and causing a life shortage is how the AFC system can be effective.

53:28So AFC typically require a sudden input and a sudden output from the battery pack. And typically it has to be fully discharged under like 15 minutes and fully charged in like 30 to 60 minutes under like the peak loading condition. So in that case, it's mostly about the heat build up and how we can cool down the heat from the system. So that's one of the typical usage for AFC. So let's say a more commercialized version of the energy storage system. Tesla call it the power wall. And there are also many other suppliers, especially in Japan because of their tsunami and earthquake. They are quite focused on the household energy storage. And for household energy storage, typically you buy the system to have it operate more than 10 years. Sometimes it can go through 15 years. And during that cycle, most battery are placed outdoors. So in that case, the heat doesn't come from the battery itself. It actually comes from the environment. So during the summertime, the outside temperature can reach like 35 to 40 degrees Celsius.

54:54And during the winter time, it can go as low as like negative. So in that case, how to maintain the temperature inside the battery can dramatically affect that kind of lifespan. So if a battery is not safely operate for most household ESS, it can only last for like, let's say three to five years. And if the temperature is well controlled, the entire life can go to 15 years. So that kind of like three times more lifetime expansion is going to cause a huge commercial impact for that kind of system. And last example, it's about an uninterruptive power system. We call it UPS. UPS is quite important. And it's one of the substitute for typical gasoline generator, or they can integrate together depends on the situation. And for UPS, it's the most severe kind of ESS compared to all the other criteria. So it's not about for UPS case, it's not about lifetime. It's about the system reliability. So you want to make sure every time you need the UPS, it has to work.

56:15Otherwise, like the hospital will short off electricity and a lot of like life maintenance equipment will just be shut off. So for UPS, thermal management is mostly keeping the reliability of the system to make sure if at that particular point where you need a dramatic amount of energy from that system, the thermal management has to be controlled and make sure the battery system can deliver the power you need at that specific point. Yeah, so basically to sum up, it covers from the AFC and also the household ESS to UPS. And the commercial side, it's heavily depending on two factors. One is the battery lifetime and the other one is the system reliability. So it all comes to the matter where why you need this system and the critical point for the failure of the system and how the temperature control for the battery can make sure the desired performance can be achieved during the operation. Thank you, Gigi. That's extremely informative. Fantastic. Yeah, thank you again. I think very interesting points and also looking forward to have you involved further.

57:42Next week we have a session on policy and it might also be something quite interesting to have you involved there. Tarek, would you like to go next? Yes, thank you very much. I have one question to Gigi about this internal resistance of the battery. He mentioned that it is inversely proportional to the thermal activity. Sorry. Which is a contradict with the normal behavior of electrical resistors. So any reason for this behavior? Hello. I want to clarify your question first. Do you mean like the reason why the temperature increase in the battery cell will have a lower internal resistance? Exactly. Okay. Yeah. So it's about the chemical principle around it. So let's go back to the battery cable wire. Typically for a copper metal, if you have a higher temperature, then the resistance will build up. So the reason behind it is simply like if the temperature increase, those metal will have a lower electrical conductivity. And it's because at a higher temperature, the electron inside is less likely to move because those metallic elements will be more active.

59:17And once the metallic elements such as like Cu plus for copper, for example, then it's going to like affect the electron, which is E minus, to move through the copper wire. And if the copper, the electron is less likely to move through the copper wire because of the metallic ion, it's interfering it, then that will reduce the electrical conduction and therefore cause the resistance to build up. So this is why like typical condition when the temperature increase, then the resistance will increase as well. Yeah, that is understandable. When you have a higher temperature, you have higher resistivity for the copper, for example. But you mentioned that the battery will have lower resistance, internal resistance. This is my question. Yes, so I will follow on this. So battery has a fundamentally different chemical property compared to, let's say, a copper wire. So how battery works is that the electron travel from the anode to the cathode. And there is a material called separator in between them.

1:00:47And also the electrolyte is the liquid that is carrying the electron to go from the anode to the cathode. So the resistance actually comes from whether the separator can be effectively like, make sure the electron can travel in between those. So it's actually the other way around where if the battery temperature build up, then the electrolyte will be much more active. So the electron can carry the electricity much faster throughout the separator. So there is no like metal material that is actually blocking the electron from passing through. So that's why when at the battery level, when the temperature build up in a certain range, then you have a much better electrical conduction. And do you have any way to detect this internal resistance and control the charging, for example? Yeah. So for typical measurement, we do it in two ways. One is through AC, so alternative, alternative current. So it's called AC IR. And that is the fastest way to sourcing the battery cell and also to make sure the internal resistance inside the battery cell.

1:02:27And the other way is direct current, the DC IR. So it just using a direct current to measure the internal resistance of the battery cell. And during the typical operation, typical BMS on the vehicle can measure DC IR when the vehicle is operating or if a energy storage system is discharged or charging. And the way that how the system knows if we can charge on a certain rate was that once the internal resistance reach a certain point, then the current can flow through it under a much higher rate. So if we are doing, let's say, a 2C charging compared to 1C charging, then that will give us like 30 minutes to full charge compared to an hour. And if we want to do that 30 minutes fast charging, then we need to make sure the battery internal resistance is low enough. And also to make sure we are under the desired temperature range for that battery cell. Yeah. So basically it's through the internal resistance measurement and mostly on the vehicle side is through DC IR.

1:03:44And if on the external machine we use AC IR to source out because if we are doing DC IR, then we have to run through like a little of the discharge and charge to the battery. And it only allowed when the battery is connected to a load or if that's hooked up to the system. Thank you very much. Thanks so much, Tarek and Gigi. We have about 25 minutes left. So I'd like to invite Ross and Milo to share your thoughts on this, if we could go in this order. Yeah, this is Ross. Certainly Glenn brings up an interesting point though with the vehicle to grid question on thermal management at least. Because again, as Gigi said, you will decrease the life of the battery by of course using it more frequently and draining more energy from it. From a thermal management standpoint, you know, a moving vehicle, let's say with liquid cooling of course, has its cooling, you know, regulated somewhat by the movement of the vehicle itself.

1:05:04You're passing through the cooling system to cool the fluid. And the same thing again in a passive or an air system. But of course, now that that vehicle when it's sitting stationary and let's say a garage and you're still discharging energy from it to support the grid. You know, how does that thermal management system now adjust? And what are the limitations you place on the battery so that let's say you don't overheat it, you know, while it's operating? So I don't think, you know, manufacturers of autos have taken that into consideration yet. But as you we look to move forward, it may be that, you know, the battery management system itself on the vehicle will, you know, have to make some adjustments such that, oh, okay, we can't discharge this battery more than this particular rate. Because we have to control the temperature because, again, we don't have our active cooling system working as intended because, again, the vehicle sitting there stationary. So interesting adjustment I think we'll have to make is companies like VW that want to really utilize that battery to support the grid going forward that will have to be taken into account in the thermal management system itself.

1:06:24So, yeah, yeah. Hello, Ross. Thank you for the question on that. I think to answer like whether the automotive manufacturer, they actually consider the thermal management as a critical factor, it really depends on the cost performance perspective for them. So, most manufacturers, they don't really just do it because it increases your performance. They also consider if that kind of cost spending is going to worth it. So, for example, like GM, even like General Motors, they know exactly how all this system work. They still decided to take away the active cooling at all because they think that it's going to reduce the battery costs and they don't want to spend any penny on increasing the battery costs because they think that it's going to be a lot higher compared to a typical IC engine. So, that's why like you may mention that most of the automotive manufacturer, they just don't put too much effort on it because thermal management does not have an instantaneous effect to the battery during like, let's say the first one to two year operation.

1:07:55So, imagine like you own an electric vehicle and it can be dialed because you don't use the battery so frequently. But that doesn't really show up at the front. So, for most of the low cost EV, such as like Volkswagen ID.3 or Tesla Model 3, they do integrate those systems but it's not also their main focus on it. So, they will probably get focused more on like, just the reliability such as like battery cell selection or the battery cell connection because those can be the direct impact to the driver during the first one to two year operation. But if we increase the time span and also we increase the use of the vehicle then the key success will come from whether you can manage the battery wheel. And part of it is thermal management but also the other part of it is the consistency of the battery. So, in this case you want your battery pack to degrade under a control factor and also to make sure the degradation is within the linear tendency that you expect.

1:09:20So, in that case you can have a really steady degradation and make sure the vehicle still works. But the worst condition is, let's say, pass through the first three years, then the battery cells start to build up the inconsistency across each other. And in that fact, it could actually cause a non-predictable degradation across the whole lifetime. Which means like after three years, you may just have your vehicle stop working or it just cannot work during like your daily ride. And that happens a lot for most Chinese vehicle manufacturer such as like Neo EV and Xiaopeng. It just like Chinese government are really good at like message control. So, there are a lot of like vehicle explosion or battery hazard condition that does not be reported. But back to the thermal management system, it's mostly about how you can control that degradation factor across the whole vehicle lifespan. So, let's pull up another condition where thermal management can be useful. It's when you place your vehicle stationary, let's say, in the summertime and outside for like a week, and then you want to drive it again.

1:10:47So, during that kind of condition, your vehicle is exposed to direct sunlight. So, inside the vehicle compartment, the temperature can potentially build up to 70 to 80 degrees Celsius. So, in a typical condition that could be quite a damage to battery sale and potentially cause like the battery sale failure directly when you are having your environmental temperature that high. And if the vehicle has the active cooling system starting when you are not using your vehicle, then the answer is yes, you can control the temperature. But from the system level, you may run out all your electricity when you are doing so. So, that's one of the fragile parts about the current electric vehicle technology. It's that electric vehicle, it's so sensitive to temperature impact. Even if we may say the cost for battery is going down and we are having more and more vehicles on the road. But the fundamental issue with battery is still, if the battery is exposed to a huge temperature difference, then it's going to have a tremendous damage no matter how you control it.

1:12:14So, thermal management is one of the critical issues to reduce that effect. But fundamentally, it's also coming from the sale property. And that will bring up another issue for how we can improve the battery sale either by using solid-state battery or other type. But it's not our main focus today. But to just summarize the thermal management on most of the automotive makers, they don't think that it's one of the very critical factors for the customer to observe. But for the high-end vehicle manufacturers such as Lucid Air, RIMAC or Porsche, they do a lot of effort, especially on the thermal management part, to make sure the battery can perform as the way they want. So, it mostly depends on the use case and on the cost perspective for the vehicle. Yeah, I think I'll hand back to Simon or Catherine because I think he's offline. Thank you so much, Kiki. This was a really interesting insightful overview again. Great, just looking at the time, so we have about 15 minutes left.

1:13:39And usually, you know, time flies by also in the past. I've also looked at quite a few of interesting profiles in the audience. I also invited some of you to come up, but maybe you're busy. I can absolutely understand that. I mean, it's very normal. But yeah, just an invitation. We have about 15 more minutes. If you have any questions about thermal management or anything related, feel free to use the chance now because I think you can tell that Kiki and Catherine have tremendous knowledge on this topic. And it's really fortunate for us to have them both with us today. If anybody wants to come up. Otherwise, also, I mean, I can keep shooting questions for anybody else. My loss, if you're maybe still driving or make your Atari can also, of course, ask more questions. I'm just kind of like maybe like one last thing, but just also because you mentioned Tesla many times before. And for me, kind of when I, you know, when I stood in the beginning, you know, I think kind of like, you know, creating their pack and the cooling was their, you know, unique kind of, let's say, you know, the USP or the unique selling point in the beginning or their, you know, their kind of technology or their invention or so.

1:14:44I'm quite curious now because you mentioned there's a wax, you know, the technology you're developing with your startup, which I think sounds really interesting. So I'm just trying to get my head around how passive it is. So for example, if you now have, let's say, a stationary system and you would use your technology, this means there's no active kind of moving, no moving parts in a way. Is this correct? Is like this wax all stationary or is there any like moving parts similar to like any other active cooling? Yeah, for, for our technology, we do not typically require active cooling. So let's say if we are using an energy storage system, then it just typically we put our material inside the system and that would be pretty much it. So the reason was because like mostly on the cost perspective for their system. And we can also combine like liquid tubing and other active cooling device with our material. So that that can be used for larger size vehicle application.

1:15:58But from our experience, when we talk to the customer, they have many, many other reasons that they don't really like active cooling. So let's say if we are targeting a motorcycle market or some of our motorcycle customer, they have really severe volume and weight constraint. So in that case, they don't really have external spacing for liquid cooling. But also the operating condition is quite similar to most of the automotive cases. So in that case, they have to suffer under a high ambient temperature. And also they have to do instantaneous high C-ray discharge and also support fast charging. But also they cannot allow a liquid cooling system that is going around the battery pack. So a lot of that kind of severe condition was addressed for our material uses or our thermal system design. But I think the key questions always come back to how you want to balance your performance and the cost. And also how you want to make sure the thermal system is integrated in the way that the increase in your performance is going to compensate the increase in your cost.

1:17:27So from a commercial or business point of view, it's a matter of like how easy you can manufacture the battery pack with this design thermal system. And also, secondly, it's about how our material can fit into the system and increase your battery safety and also the battery lifetime. Yeah, I can ask now the question. So maybe some simple question. For the cylindrical batteries, especially the new tubeless battery, it's probably more beneficial to cooling thermal management from top and bottom of the battery than from the tubeless battery than from the side of the cylinder. Is that right? Yes. So do you have some experience about the thermal management of those cylindrical batteries? Yeah, so are you asking me to maybe share like how to design the system for cylindrical battery to effectively cool it down? Yeah, I'm asking that usually what I see in the thermal management or cooling or warming the battery pack, it's usually from the side of the cylinders. Basically, thermal management material is placed on the side of the cylinders. But I'm saying that for the cylindrical batteries, it makes much more sense logically for me to cool it and warm it from top and bottom of the cylinder, not from the side of the cylinder.

1:19:21Yeah, I understand. Yeah, so let me give you like couple examples for how people actually do it. So let's say a cylindrical battery cell, you have three contact surfaces, the top, bottom and the side. And when the battery is like heating up, typically the heat is collecting at the anode and the cathode, which is like the bottom and the top of the battery cell. And also like the bottom and the top will be hooked up to let's say wire bonding or like a nickel strip that connect to copper busbar. So in that case, it's much easier to connect to copper busbar. So in that case, it's much easier to dissipate heat from the top and bottom compared to the side of the battery. So like couple people that are doing it, especially on supercar, it's like Remac from a Moonlight. Croatia and also Lucid Air is like Lucid Air is like luxurious sedan. So what they are doing is they want to reduce the weight of the vehicle as much as the battery.

1:20:14So in that case, it's much easier to dissipate heat from the top and bottom compared to the side of the battery. So like couple people that are doing it, especially on supercar, it's like Remac from a Moonlight. Well, the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the bigger the But again, like, it only handle like instantaneous heat dissipation from top and bottom.

1:21:03So in other words, it's that during the time spent, if the battery still got heat up, then the heat will still be distributed across the entire battery seal. And the reason why those supercars are doing it, it's mostly because they want to reduce weight and to offer the maximum allowable cooling effect to the battery seal. But from the other side, if you are designing something with a much higher lifetime and reliability, then you want to make sure you get as much as contact with the battery seal as possible. So in that case, you can dissipate heat more throughout a evenly across time span. So that's why like Tesla was using the snake tube design. And also, I believe another company called Proterra, they are based in California that developed like e-bus or larger scale vehicle. And for those vehicles, they also use cylindrical seal. And what Proterra do the most is they use a evenly distributed thermal management system that is taking heat away from the side of the cylindrical seal.

1:22:27And the logic is quite simple. So the other thing is that even the heat gather mostly on the top and bottom of the battery seal, but the heat will eventually be spreaded out to the side of the cylindrical. And the largest contact area for a cylindrical seal is actually on the side. So the area that is like rapid or around the battery seal, comparing to the top and bottom, because there are only two like circles on the top and bottom that you can contact with. So if we are looking for a larger size battery pack, or if we are looking to design a more reliable and also a more durable battery pack, then how the designer or the engineers will do it, they typically want to take as much heat as possible and as evenly across the entire pack, instead of just like handling those instantaneous conditions. So that's two kind of different design concepts between a sport car or race car compared to a commercial car or heavy duty vehicle.

1:23:46So does that kind of answer your question? Yes, partially, but another logic for me, it seems to me in the bigger cylinders, you need to use top and bottom approach because from the side you are not equally cooling or warming the whole electrode evenly because the heat needs to travel a much longer distance, a longer distance from the side than from the top and bottom. Yeah, so I think it's not like a matter of like, do we just pick one? So typical battery pack design, it will integrate like both the top and bottom cooling and also the side cooling. So one of the examples I think is done by Porsche. So what Porsche was doing is instead of like a cylindrical cell, they use a pouch cell. But the idea is quite similar is that pouch cell, they also have a highest temperature gathering on the top, especially on the top when they have both electrodes sticking out on the same side. But what they are doing is they will cool down the electrode, which is like the the metal part that carrying the electricity by let's say a copper busbar or a fin design.

1:25:30But also during the side of the battery cell, they will also use like a thermoconductive plate or also sometimes they'll integrate like micro cooling tube in between those battery cells. So a typical pack designer, what they are thinking about is if I really need that kind of design across my battery cell and if I need the thermal design, then which part has the most heat gathering? And the final question comes to like, do my design it's enough for let's say taking the heat away? So if I just take it from the top and bottom, is it enough? Or if I take it from the side, is it going to be more effective? And it mostly depends on the battery using condition and how you will drive that vehicle. So it doesn't just stick to like one solution. It mostly is a combination of multiple solution and to balance it out depends on the trade-off between each of the design. Maybe my last question would be, what do you think about the thermal management of the new battery from Tesla 4680?

1:26:57Means that a tubeless battery and bigger, much bigger battery, much bigger cylinder, it's more suitable for the better thermal management or more problems for the thermal management? Yeah. Yeah. Um, you're talking about the 46800. So the latest battery cell size. Yeah, yeah. 4680. 4680 they are calling it not 800 because they removed zero. Okay. Yeah. So personally, I think it's going to be, it's more cost saving. So that's what Elon Musk's was like, emphasize on because they think a larger unit battery sale can reduce the production cost more. And also it can be more rigid on the battery pack construction and even combined with the chassis. So the reason was because the current production of the 21700. So the reason was because you are sticking much more energy inside a single unit now compared to the current 21700. And that could potentially cause another issue where if one of the battery sale has a failure, then it's going to have much more heat dissipate out from that specific sale.

1:28:43And that could potentially be a much greater impact to the whole battery pack. And also because it's like, it's like having more energy inside a particular unit. It means that the heat will be generated more inside the cylindrical shape. And to compare this, we have like conventional pouch sale, which has like similar capacity to the latest 46800 sale. And, but the difference between them is the shape. So conventional pouch sale, even if it carry the same amount of large energy, it's like a flat shape, like a sheet of paper. In that case, it's going to have a much wider distribution of temperature. And it's going to be better for thermal management compared to a cylindrical sale. And for the latest 46800, because the cylindrical tube is going to be less, I'll say like less temperature distributed. So in that case, it's that the temperature could be gathering in the center of the battery cell. And typical, like for the current 21700, the center of battery cell can reach almost a thousand degrees Celsius, while the surface of the temperature, the battery cell is around like 50 to 55.

1:30:22But if we are going for 46800, then the center of the battery cell is going to be way higher than the current model. And in that case, it's going to be worse for the thermal management. And the last part is... Unless you will cool it and warm it from the top and the bottom, because in that case, even your center is equally cool, like your sides of the battery. That's what I was having with my questions in the beginning. So because it takes you only 80 millimeters or only 40 millimeters to cool it from top and from the bottom to the center of the battery. And equally, it's cool to inside of the battery and outside of the battery. And when you are cooling from the side, you are going like several meters towards the center. So it takes you much more time and it's much more difficult to cool from the side than from the bottom or from the top. Great. Just also looking at the time. I mean, I feel like we could probably talk about this much longer as well. But I think, you know, we had one half hours and we want to kind of also respect the ones time. You know, some people have to kind of jump off. So I think we can maybe also put it to a close here. And maybe, you know, there are probably some follow up discussions also coming from that.

1:32:00But yeah, if you don't mind, I think that would be a good time. Can I have one question? One last question to Gigi. Gigi, can you in one minute, for example, talk about this solid-state batteries status now in the world? Please. Okay. Do you have a clock watch or something so I know exactly one minute? No, sorry. I'm just saving time for Simon and Katrina. I'm just joking. Don't take it seriously. Okay. Yeah, I'll just go really quick on it. So, solid-state battery compared to like current like an MC battery, it has like at least five times of energy density, which means that it's going to be only 20% of the weight compared to the current battery. And also the great part is because why we call solid was because like the electrode inside is solid. So that means that it doesn't really have a liquid inside, which will increase the safety a lot more. So solid-state battery don't explode and they are quite safe for operation. So if that's the case, then we don't have to worry about any of the hazards coming on. But the main technology progress now with solid-state battery, it's on their anode and the cathode material. And that also come with one of their biggest issue now is the electrical conduction. So solid-state battery is not really a new technology.

1:33:40It exists like starting from 10 years ago. And most of them are using military application, especially on desert environment. And because solid-state battery needs a relatively high ambient temperature, let's say above 50 or even 70 to 80 degrees Celsius in order for it to have a really good electrical conduction. So in that case, it cannot be used for a typical using scenario, especially on vehicle. So people are trying to solve this problem by improving the anode and cathode material. So there are many companies out there, they claim that they are having new material with a solid-state battery. And that's the reason because most of the solid-state battery, they have issue with their electrical conduction. And for the current forecast, scientists believe it can go into production in by like 2030 or 2035. But I think a more practical estimation is like it will take at least like 50 years for steady mass production and use on electrical vehicle. But if solid-state battery can have a cost reduction, and also it can be widely produced, then for sure like it will totally replace the current IC engine, because it's going to have a much longer range compared to IC engine, but also with a much greater efficiency. Yeah, so that's pretty much about the solid-state technology. And speaking of the market, Toyota is also investing in it. But what people are more interested is like Ford, they just start a US production facility to work on solid-state battery. And there's another company called Scion Power in the US.

1:35:52So they focus a lot on solid-state battery technology, especially on integrating that on the current vehicle uses. But again, because those batteries are not well developed and good for manufacturing. So it can be a future vision, and it's for sure a right direction for the battery progression. But it's still far away from going into the market and for production. Thanks so much, Gigi and Tarek. It's come to the end of our session. If you'd like to catch on the other topics, we've also actually talked about different types of battery chemistry in our previous session. So feel free to check batteryinsiders.com for the previous session. So yeah, so thank you so much today, Gigi, and the rest who have joined us on stage. Hope this is helpful to you. Thank you. Thank you. Thank you. Thank you. Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well, Well,