304 The Future Battery Chemistry Episode

Gary Comerford (: 00:00

We've spoken about batteries before on the show. Dr. Euan McTurt, battery electrochemist, came on and gave us chapter and verse on caring for batteries, how to properly charge a battery, and we dispelled a couple of myths about batteries.

Now that was almost three years ago. And while his thoughts about battery care, Chadmo charging, and whether lithium-ion batteries do explode as often as the media would have you believe haven't changed, the battery market has. Now, today I want to look at battery design, touch on topics such as solid-state batteries, different battery chemistries, and what difference something as simple as a battery anode material can make to the battery itself.

So welcome to the future of batteries episode.

Hi, I'm Gary. This is EV Musings, a podcast about renewables, electric vehicles, and things that are interesting to electric vehicle owners. If you want one of these mugs, let me know, we'll see whether we can put some together. Now,

before we get into the main bulk of the episode, can I ask a small favour? A like, subscribe or a comment would be most appreciated if you found this episode useful.

As an electric car driver, you're probably going to be acutely aware of your battery. If you listen to the naysayers,

They'll tell you it's gonna either burst into flames, run out of charge, die after about three years, or all of the above.

Now whilst none of that is accurate, there is a case to say that what your battery is made from and how it deals with things such as charging, heat and cycling is something quite important. So it's one of those things of which it's always interesting to be aware.

Now, before we go much deeper into this, let's just look a little at battery basics. At the most simple level, a battery is a device which causes electrons to flow between two points. This flow of electrons causes a current, which in turn creates electrical power. In most batteries, you have three different physical parts: there's the anode, the cathode, and the electrolyte. The anode is the positive terminal of the battery, the cathode is the negative terminal of the battery.

And the electrolyte is the medium through which the electrons move.

Throughout the years of battery development, the trick to getting better batteries has been to modify one or more of these three components, and this is usually known as altering the battery chemistry.

Back in time, the predominant chemistry was lead acid. Then we moved on to zinc carbon as a battery chemistry. This had a zinc anode and a carbon cathode. Ammonium chloride formed the electrolyte in a paste form, not completely liquid but not totally solid either. And we'll come on to solidate batteries in a moment. Then we moved on to this breakthrough tech, which was lithium ion. And what this meant is that the anode is made from graphite or carbon.

The cathode from a metal oxide such as lithium cobalt, lithium ion phosphate, or lithium manganese oxide. The electrolyte has various compounds, but the salts used in it is something usually such as lithium hexafluorophosphate. Now, this combination of different compounds creates a stable battery that has a good energy density and can be cycled, i.e., charged and discharged many times without a big loss of capacity, the so-called degradation.

Now you've probably heard about solid state batteries as well. They seem to be the holy grail of battery tech at the moment. The main difference these have to the current crop of batteries is that the electrolyte in the middle is not liquid or aqueous, it is, you know, solid. But looping back to the anode and cathode, these are the two main areas in which innovation and progress can be made with batteries. But with all these different battery chemistries, there's always a trade off. Cobalt in batteries is something.

Of a hot topping amongst those who want to find a a stick with which to beat EVs, for example. Cobalt is generally used in the anode alongside lithium in the lithium cobalt chemistry, but there are new chemistries coming out which don't use cobalt, lithium iron phosphate or LFP for one. And what it's worth remembering for different chemistries is that there's always a trade off to be made when altering the chemistry. So as an example, LFP.

Doesn't have as high an energy density as lithium cobalt. This means an EV with a similar size battery won't travel as far. But the upside is that LFP batteries can be charged to 100% and kept there with no adverse effects. Now I could go on for a while regurgitating stuff from the internet about batteries, but I think the best way to look at things is to get our favourite battery electrochemist, Dr. Ewan McTurk, on to give us chapter and verse. Now we'll look at BYD's Blade 2 battery.

the donut, solid state batteries, sodium batteries, carbon batteries, air batteries, etc. Now Ewan does go into something of a three-letter acronym Frenzy at one point, so I've added in a glossary of terms to the show notes.

Gary Comerford (: 04:57

So good morning. Can I actually start by introducing yourself and tell the people where they might know you from, you work, what you do please.

Dr Euan McTurk (: 05:04

Hi Gary, I'm Dr. Ewan McTurk. I'm a consultant battery electrochemist from Plug Life Consulting and I work on anything technical, strategic, or public outreach to do with battery electrochemistry, EVs, charging infrastructure and static energy storage. And you may have seen my YouTube channel, Plug Life Television.

Gary Comerford (: 05:22

I want to chat with you today about where the battery market is going in terms of innovation. Now for years, we had lead acid batteries and a few slightly esoteric chemistries around there. Then we seem to have settled on MFC chemistry with the advantages and disadvantages of that. And more recently, LFP has come out as a chemical choice for many EVs mainly due to the safety issues and the fact that you can charge it up to

100 % without any problem. But from time to time, we hear of other chemistries that might be coming forward. Now, many of them are not necessarily intended for electric vehicles, but I want to have a bit of a discussion about them anyway. So sticking with lithium based batteries, have lithium, manganese, oxide, is it spinel? Spinal?

Dr Euan McTurk (: 06:04

Yeah,

yeah. so you're you're looking at kind of lithium manganese Redshaw LMO. And that LMO has been around for for a while, the initial kind of versions of it in Power Tools.

Part of the problem is that the cycle life on it was typically quite short, and that's why you never really saw it in electric vehicles. But the likes of Ford and GM, it seems to be quite popular amongst American automotive OEMs, this this chemistry, because they're used to NMC and lithium manganese rich has similar kind of properties in terms of voltage and so on. It's a bit of a drop-in solution without necessarily having to overhaul the battery management system and the you know the the wiring.

thereof. But yeah, you are displacing expensive nickel and contentious cobalt, which is also expensive, with cheaper, more abundant manganese.

The issue has been getting the cycle life up. that has now seemingly been achieved by GM and Ford. And I suspect that the US market will go fairly big on lithium manganese rich because there is this push towards stupidly high range, because Americans and Canadians drive stupidly long ranges because they don't have a decent public transport system.

So you know, as you are entir pretty much entirely dependent on your car, you want that to be able to go as far as possible. And that's why you know that's how they will get to their sort of four hundred plus mile pickup trucks and stuff like that. I can't see that being of as much interest in Europe where there's going to be the push towards LFP for cost

And also because the range has managed to improve through clever packaging, moving from cell to module to cell to pack and then cell to chassis designs. but with LMFP, the likes of the BYD Blade two point coming on the market, we will start to get

Reasonably close to the same kind of energy density as NMC. Not quite, but more than good enough for European EVs and their range. So you know that easily covers the UK market, French, German, Norwegian, all the kind of key cases. interestingly, with LMFP, there's a UK company called Integrals Power that has demonstrated their LMFP cell and its ability to withstand very cold temperatures that would be the equivalent of Norwegian winters and so on, whilst retaining some.

Like 80% of the capacity of the battery. Whereas LFP, conventional LFP, you'd be down to about 60% of that capacity at best. So that's important for us. But when you look at the US,

the focus seems to be on lithium manganese rich because you are maintaining the exact well almost the exact kind of energy density that you would get out of NMC, but you're just making it cheaper to manufacture and you've got less reliance on you know, chemicals, raw materials coming from contentious nations and supply chains and so on.

Gary Comerford (: 08:59

So the one which I think is almost not identical, but it's very, close to is lithium titanate oxide. What's the subtle difference? What are the pros and cons? What would the market be for that?

Dr Euan McTurk (: 09:13

So lithium titanate

CIB battery back in the early: 2010

The range was less, but the lifespan was stupidly high. So I'm pretty sure that any of those that were sold in Japan will still be running around with a perfectly healthy battery in it. That cannot necessarily be said for the ones that used the earlier conventional lithium ion cells. certainly the ones that were made pre twenty twelve were known to degrade a bit faster than the ones that had a subtle upgrade in their their battery chemistry after that. But lithium titanate, that is not a change in cathode chemistry, positive electrode, it's a change in anode chemistry.

The negative electrode. So instead of removing NMC, you're keeping NMC typically and you are replacing the graphite with lithium titanate. It's a completely different structure from graphite and it allows lithium ions in and out of it very quickly with minimal expansion. And as a result, you've got very low internal resistance, you've got good C rates, at least 4C, so you could charge the thing in 15 to 20 minutes if you if the car was capable of it, if the you know the power electronics and what have you were capable of it.

so yeah, quite impressive in that sense. There's another clever trick up its sleeve, because it doesn't expand or contract much,

It doesn't physically break itself apart. So the cycle life is in some cases over 20,000 cycles in comparison to what would have been about 2,000 cycles for conventional lithium-ion cells back then, although they're starting to improve today. But the other clever trick about NMC is that the actual anode structure itself acts as its own internal fuse. So if you were to do puncture with a steel rod or something, one of these kind of puncture tests, penetration tests on an NMC.

C

cell, you probably wouldn't be looking at much because the area of the lithium titanate around that that metal short circuit.

changes from a highly conductive phase to a highly insulating phase and acts as its own fuse. So it vastly slows down the self discharge. So, I I've seen videos of of crazy people in back gardens and stuff who've taken like an N Cell, an L F P cell, and a lithium titanate cell, and, you know, they've done the puncture tests, they've done the flamethrower tests, they've done all sorts of nuts things to them to really abuse them. And of course, you know, the N C cell's a bit theatrical about it. We we know this. You know, conventional graphite N C is

is quite blowy uppy if you are determined enough. LFP, you know, there might be hot gas vents, but it's vents from it, but it's generally a lot safer. And then NMC

nothing much happens. I mean you can get them to catch fire if you are determined, but I can get my office desk to catch fire if I'm determined. So you know, it's it's not gonna blow itself up unless something catastrophically went wrong. so L lithium tysonate LTO

The market for that in EVs, the IMEV, as far as passenger cars go, was the exception that proved the rule. It was also the short-lived concept of the Lightning GT sports car in the UK. They talked about using Titan itself, but they never really got off the ground.

Where we're starting to see titanate being used, because the energy density is much lower than for NMC and lower than for LFP, because the potential of titanate anodes is one volt higher than graphite. So you've instantly reduced the cell voltage. And because, as I'm sure we've discussed before, energy in watt hours is equal to voltage in volts multiplied by capacity in ampere hours. If you reduce the voltage, you reduce the energy, you reduce the range. So

These are gonna be in niche applications. They have sometimes seen use in electric city buses that have pantograph chargers at each bus stop because they're able to charge up so quickly, but it's a fairly short range, so it you know pootles along to the next stop, charges for a few seconds, pootles along to the next stop. That's where it makes sense. I believe that in fact, yeah, rail applications are starting to use this as well. If you look at the likes of Stadler, who make loads of different rail traction, whether it's like, you know, massive locomotives for

hauling loads of of weighty freight and so on, or whether it's you know, the the multiple units that are used for commuter services and things.

I've seen the the kind of industry rundown of who's using what, and I swear there's someone in the board of Stadler who's like, How about this little electric commuter train, LTO? How about this big meaty freight train, LTO? And they just it's like, We know it works, we know it's safe, we know it's long lasting, we'll just use this. But what about the range, sir? who cares, LTO? And that's what they're doing. But you know, so you'll find that the the range will be comparatively limited, but the lifespan will be excellent. But where

it gets interesting is that L F P is starting to to

Equal the lifespan of LTO, but with improved energy density. You look at C ATL's electric bus battery, which can do SLFP. I've forgotten what the energy density is, but you'll get more range out of it than an LTO battery. And the warranty for that is 15 years or 1.5 million kilometers, which is almost a million miles.

you know, that that is a much cheaper chemistry and it's very long lived. So one would argue that LTO's days potentially could be numbered in some of these applications. They will inevitably continue to see niche use. But yeah, I I i it's genuinely

It's a bit like the the old kind of hydrogen's the future 'cause it can do this that batteries can't, the conventional batteries can't, but conventional batteries very quickly caught up with hydrogen and the noose is very much around the neck of hydrogen. Batteries like L F P, LMFP and to an extent N C graphite are starting to kind of circle around LTO and really limit the number of applications that that uses. Or that that's used in.

Gary Comerford (: 15:00

Can we do a quick sidebar here? Because I know when we talk about battery chemistries and you've thrown around a lot of TLAs, a lot of three letter acronyms,

Dr Euan McTurk (: 15:08

yeah, so

Gary Comerford (: 15:09

every combination of elements that you put in or compounds that you put into battery will give you, there is always some sort of trade off that you're making in some way, shape or form. Do you want to give like a quick sidebar about what the potential trade-offs are?

not for every individual chemistry, know, for certain types of batteries, as you've said, you might have longer range, but shorter cycles, you might have a higher fire impact. What are the general trade-offs that you make when you're designing a battery?

Dr Euan McTurk (: 15:43

So yeah, I mean there are numerous factors to consider. Cost is a key one these days, especially for the automotive sector. And if you use cheaper materials then you're gonna get a cheaper battery, but you're probably gonna get less range per charge. safety is a key one as well, where if you tend to use more docile materials, you either end up with in fact no, you do tend to end up with reduced energy density, so reduced range, because that would either be your lithium titanate or your LFP, which would be considered safer.

but they both have lower energy density. if you want stupidly high performance, you're typically trading lifespan for that. although we're starting to see some batteries that might buck the trend on that through incredible molecular scale engineering like the Blade 2.0, which is pseudo-affordable at least. the lifespan seems to be reasonable. you know, it doesn't reach the lofty heights of lithium titanate or some conventional, I say conventional, long life LFP, but it's

It's

still respectable lifespan for for a car. the chassis should be starting to rust through before those cells fail, but you've also got stupidly high performance. So yeah, that's that's starting to to change. But the general rule was that performance, high performance equals shorter lifespan, and that lower cost and improved safety equals lower range. But that's that's starting to change now, with new chemistries that are on the horizon.

And what's interesting

ook at EVs in the mid to late: 2010

Either of cells or of complete cars. But we're starting to see new chemistries like sodium ion, like lithium sulfur, like silicon anodes within lithium ion cells, solid states, semi-solid states, etc.

A lot of these have trade-offs of lifespan. And, you know, we've been able to demonstrate significant improvements in energy density for the use of silicon anodes or or solid state cell architectures and so on. you know, you can talk about kind of doubling the range of an EV, etcetera. But lifespan is one of the issues that we're facing at the moment, and it needs a bit more development in the lab to get lifespan up from hundreds of cycles to thousands that you would need for a car. But

Such are the turbulent times that we live in, and

that the startups who are manufacturing these next generation cells have pivoted away from automotive towards drone batteries. Because funnily enough, there's a lot of militaries out there, particularly in the US and Europe where a lot of these startups are, who are keen to use local supply chains for strategically important reasons. and when it comes to, you know, the the performance of those batteries, they need as much runtime as they can get out of them. But because they're military drones, they don't often expect them back. So

So it's actually you know, it it's it's also a really high markup that these startups can make off of it because it's a military application. Whereas automotive they will really try and keep those margins low, you know, a lot of these startups can charge pretty much what they want to stick these batteries in military drones. So yeah, a a clear ethical dilemma for these startups who would struggle if they were to see their batteries through to automotive scale readiness, commercial readiness. But this is actually giving

an opportunity to be a kind of a living lab, a rapid prototyping of these incredible new chemistries, which will hopefully eventually reach the stage where they are doing thousands of cycles and are doing good things, ferrying people around in cars and buses and ambulances and you know other things that are positive for society.

Gary Comerford (: 19:30

me little bit about, you mentioned them a few moments ago, there's sodium batteries, think 11 labs, so somebody who's put together a working version of this, what's the pluses and minuses of sodium batteries?

Dr Euan McTurk (: 19:43

So there's 11 E's and then there's 11 Energy, confusingly. And it's 11 Energy who are making sodium ion battery energy storage systems. And what they're doing is they're they're using cells from from HINA or HINA HINA brought in from China, but they're assembling the battery pack in the UK. So Haina's been around for a few years now, and there was a city car in China that was launched that used their cells.

so those are one of three families of sodium ion chemistries. Just like with lithium ion, sodium ion is a broad church of chemistries. But what you're fundamentally doing is you're replacing lithium ions with sodium ions, which are bulkier, heavier, but more abundant and cheaper. So you get a trade-off in energy density, but in theory, once you are you know producing these at the same scale as lithium ion cells, you are vastly reducing the cost. Sodium ion has a couple of advantages. first of all, you

You can use cheaper materials in those cells. So for example, the layered oxide version of the cathode, which is what 11 Energy is using, and it's what Naxxtra, which is the the C ATL sodium ion brand is using in the latest generation of sodium ion batteries in electric cars in China. So layered oxides have the greatest energy density. They are closest related to the likes of NMC that you would use in lithium ion, but there's no cobalt, there's generally not nickel.

Although there can be. Depends on how determined you want to be to take a a retrograde step. But you're generally using cheaper materials and you know the lifespan is is reasonable. The fact that Naxtras managed to get Laird Oxide to do ten thousand cycles, which is

Probably double what you would expect out of NMC today. that's impressive. The energy density on that is s it's almost similar to what LFP was doing maybe five or six years ago. so it's not too bad. Actually it's probab maybe a decade ago. But you know, it's it's it's still pretty decent. but sodium ion generally has lower internal resistance, lower cooling requirements, which means that you don't need as bulky a thermal management system, which means you can accommodate more cells in the space where that thermal management would have been in the

Battery pack. You also don't need to use copper for the current collector for the negative electrode. You don't need to use graphite. In fact, you in theory you can't use graphite. You if you can, sorry, if you're determined you can. But in theory, it's easier to use disorganized hard carbon because sodium ions are in theory too big to smash their way in between the layers of of graphene that make up graphite. So you would just end up wrecking those particles pretty quickly. But anyway, so

Because you can use more abundant materials, you can use bioderived disorganized hard carbon. So in other words, plant waste and so on. you know, like wood wood waste, etcetera. You can liter and you can use those to to make these incredibly ethical anode materials. And then you don't need expensive copper to paste that onto. You can use aluminium because sodium doesn't alloy with with copper like lithium does.

So that means you've got a lighter basset well, lighter current collector material, a cheaper current collector material. You've reduced your costs. You can also completely discharge sodium ion cells down to zero volts, which you wouldn't realistically do in an electric car, but when it comes to shipping them from the factory to wherever they need to be, you can literally put a resistor across the terminals and you'd have zero energy left in them. There's no way, even if you punctured them, you know, they're not going to catch fire or anything because there's no energy left to

you know, to have that rapid self discharge. So that means there's not as much complex paperwork and and shipping requirements and packaging and all of this and that makes it cheaper to ship as well as to make.

But there is a warning for sodium eye, and it's not necessarily going to be the holy grail, it depends on the materials that go into them. So I've recently been compiling a report for the UN that looks into the chemical risk of electric vehicle batteries at end of life, particularly in low and middle income countries. we want to try and move away from fluorinated compounds, because fluorine, if it's partially decomposed, like for example if the electrolyte salt is partially decomposed or

Or if the PVDF that's used to bind the cathode material to the current collector is partially decomposed, you can end up producing hydrogen fluoride HF, which is quite nasty. There's other nasty fluorinated compounds that can be produced if it's if it's not properly recycled and dealt with. But that is not an insurmountable issue. If it's properly recycled, it's it's no problem. It's like what if it's not? And so you would typically find fluorinated compounds in the electrolyte salt.

Lithium hexafluorophosphate LIPF six, that's in pretty much every lithium ion battery today. PVDF used in the majority of lithium ion cells as the binder for the cathode, as I pointed out. And sometimes just to be annoying, the separator, the plastic separator, might get coated with P VDF, but it's like, why would you do you don't need to. Anyway, so yeah, now that we're aware more aware of of the nastiness of of you know PFAS forever chemicals and and and and so on, we might hopefully move away from that quite quickly. So

So we're trying move away and and defluorinate our batteries just to make sure that in a worst case scenario there's nothing nasty that enters the environment. And along comes sodium ion and you know your layered oxide cathodes are fine. you've also got your Prussian blue slash Prussian white, which is basically used in in paint. but yeah, they it's it's super cheap materials.

Seemingly quite ethical. The only thing is that if it gets in touch with water, like for example, during hydromethallurgical recycling, it can produce cyanide, so you want to make sure that you recycle that responsibly and using means that are set up for sodium ion cells rather than lithium ion. But again, this is just looking at absolute worst case scenarios here.

it. That said, I think fluorine is something like the thirteenth most common

element in the world and it's also used of course in dental care products it's used in toothpaste and so on. So you know it has its uses but it can also be turned into something nasty if it's mistreated. So that's just something else to keep an eye on. But whilst it's in a battery,

Gary Comerford (: 25:29

Thank you.

Dr Euan McTurk (: 25:31

it's not going to affect you. It's just we're we're talking recycling here and and safe disposal.

Gary Comerford (: 25:36

So what about things like zinc air cells or lithium air cells?

Dr Euan McTurk (: 25:42

So lithium air cells are actually what I did the first half of my PhD on, and that would have been starting back in 2011 when they were meant to be five to ten years away. And I think that the the estimate for how many years away they are has is gradually increased ever since. So lithium air is an interesting one in theory, and it makes a very good primary battery, in other words, one that discharges once and you don't recharge afterwards. Secondary battery, bit more of an issue. So what you've got is

is a you you've got lith pure lithium on one side and you've got graphite on the other and that graphite has a porous membrane on it which allows oxygen in from the air, lithium comes across and it forms lithium peroxide or some other kind of lithium oxygen compound.

And you're talking substantial increases in energy density versus lithium ion today, minimum fourfold increase in energy density using very cheap materials. there's a couple of issues. One, you are limited by the rate of diffusion of oxygen from the air into the cell, although that's actually quite good from a safety perspective, because if you short it you could also just shut off the the cell from the air and it would just be limited by how much oxygen.

it has available to it right now. So you know it would very quickly fizzle out. but the other issue is that it has a habit of eating itself basically. So when you're using organic electrolytes, so that's your your kind of oily electrolytes I suppose if you want to be crude about it, you end up with those lithium oxygen compounds

generally being insoluble, so they kind of stick to the reaction sites within the graphite. And as a result, the cell chokes itself. But also you'll end up with side reactions where these are kind of nibbling away at the electrolyte itself. So you typically end up with a handful of cycles before you've lost a substantial amount of capacity. one of the first papers I published was on different electrolytes and basically why they don't work.

and you know, it it was it was a a modelling exercise by some of our collaborators and I was doing the kind of physical data gathering and verification of what we were coming up with with this model and proving that yeah, electrolytes that have certain very niche qualities about them that I won't bore you with just now are

better for use in lithium air, but some of them are a lot worse if they have, you know, the opposite kind of qualities to what you want. And these are the qualities and these are the electrolytes, yada yada yada. But something else that happened whilst we were there during my PhD was we discovered that lithium air cells are a bit like whiskey. There is a bell curve of moisture or of of of water ingress where you end up with like peak performance and then it drops off again.

So with whiskey, if it's neat, it's enjoyable, but it's you know it it's not as good as it it could be, you add literally one or two drops of water, wow, it really opens it up. And then if you do what you know the basically the sacrilegious thing and you dilute it with like an entire ice cube or coke or something inexcusable, it just falls off a cliff. So we had spent

All this time trying to remove moisture from oxygen that we were putting pure oxygen that we were putting into lithium air cells, because we didn't want to have any atmospheric pollutants or anything, you know, we didn't want any side reactions like that. We just wanted to get the fundamental chemistry right, then now that we'd proven it worked with pure oxygen, we can start to introduce more air-like qualities to see if there's anything that needs to be toughened up about the chemistry so it can cope in the real world.

And we discovered that actually a little bit of moisture improved the performance, improved the lifespan. So yeah, fun fact. it remains a long way away. It generally fell out of favor because solid state

became in vogue, sodium ion became in vogue, lithium sulfur became in vogue. But there seems to be

Still some research groups out there plugging away, and potentially with the advent of AI, we might be able to find an electrolyte and you know material combination that that works effectively. We've already seen some research groups using AI to try and find implausible but actually really good electrolyte combinations for more conventional lithium ion cells. So maybe that could be the saviour of lithium air, or it could just be some bright young prodigy who comes into the lab with a a good

idea and I can do attitudes. But whatever it is, it would be nice to see lithium air reach commercialisation. But if it ever does, I expect it will be doing the base load in an electric car slash range extending. Because it's not a high performance battery, it's a low and slow, long range range extender. because the maximum power, as I said, is limited by the amount of oxygen you can stuff into it, in in

You know, in quick succession basically.

Gary Comerford (: 30:15

And you mentioned there about, you know, some, some enterprising young, person coming in and finding a solution, cetera. And across that is what allegedly happened with the donut labs, solid state battery. came from nowhere. It was meant to be, earth shattering. It was meant to be a bleeding edge. I don't think he turned out that way. Do you have any thoughts about the, solid state to donut labs battery?

Dr Euan McTurk (: 30:37

Yeah, I I had my suspicions. I've been on a a couple of other podcasts, having done a bit of sleuthing myself, and in sort of in wider, informal conjunction with a lot of electrochemists on LinkedIn.

And yeah, there were there were a couple of telltale signs that something might not be right, but there was still potentially a glimmer of hope that it could be the real thing. So for a start, you know, people were saying, wow, look, you know, the the cell has managed to withstand a hundred degrees Celsius. the actual lamination on the pouch cell gave up, it melted, which would have allowed air into the cell. you know, surely a lithium ion cell couldn't withstand that.

It's really only if you like kept it on stupidly high performance for a very long time and then stabbed it with a a metal nail or something that it would have an issue with it. You know, you could have a small amount of air ingress for that amount of time and you know, a lithium air cell's not gonna be sorry, a lithium ion cell is not gonna be too annoyed about it, especially because, you know, the the the the area of pouch that had

failed on the vacuum seal was very small and it was it was kind of still kind of fairly shut together so it's not as if you had like a a massive fan blowing air into it. So yeah I wasn't convinced that that ruled out liquid electrolyte or a a you know lithium-based chemistry. Where it got interesting was the the voltage profile, the you know the discharge voltage versus time or state of charge.

And I did some sleuthing with some spec sheets and journal articles and so on. So they they claimed it was a non-lithium chemistry, probably sodium. And I took some sodium ion cells and I took some NMC lithium conventional cells and I took the discharge voltage profile of the donut battery and I put them side by side. And there was a possibility that it could have been sodium ion layered oxide.

The voltages were very similar. the the the pattern was fairly similar on the discharge curve, but it was more akin to lithium ion NMC because there was a telltale hump right at the beginning of the discharge that wasn't there with sodium ion. But

That's not to rule out the possibility that there was some funky sodium ion chemistry that might have had this same effect within it. but I was still thinking if anything, the hallmarks are more lithium ion NMC at this point. And yeah, a few others had pointed out that for example

Although the energy density was never publicly revealed, they they had photographs of these cells next to multimeters of a particular make and model. And someone measured the multimeter, used that to measure the cell, and then worked out the energy density and figured out that it wasn't anywhere near what Donut had said it was. So I think they were saying like four hundred watt hours, however many hundred watt hours per liter it was, and they calculated well actually it's it's only this many litres, which translates to only this many watt hours per

Either. but yeah, the the real giveaway that someone else figured out, and fair play to them, was that they'd actually been given data on the swelling of the cell during charge and discharge, and that was a signature of lithium-ion NMC rather than any kind of sodium based chemistry. It was like, Wow, okay. I missed that. That's good. so yeah. It looks as if it's all been a bit of

Gary Comerford (: 33:51

you

Dr Euan McTurk (: 33:51

a

Bit of a charade.

Gary Comerford (: 33:54

Yeah, and I think somewhere down the line, there's probably going to be lawsuits from various companies. There's I ran into a guy the other day who has a YouTube channel and I can't for the life of me remember what it is, but he's the one who went into extreme detail, got the lawyers involved, the whole lot to make sure that they couldn't sue him.

Literally ran into him at the BYD flash charging demo.

Dr Euan McTurk (: 34:15

Nice.

Gary Comerford (: 34:16

was there. We chatted about that for a while. So yeah. He said I was quite clear about what it was and I had to make sure that I was legally covered because somewhere down the line is going to be a big lawsuit on this. interesting.

Dr Euan McTurk (: 34:28

Hm.

Gary Comerford (: 34:29

we've taken up quite a lot of your time today. I really do appreciate you coming on and chatting about batteries. I know it's a little, it's something that you like doing and I like listening to it. So appreciate your time.

Dr Euan McTurk (: 34:39

No problem.

Gary Comerford (: 34:40

So did you get all that? Certainly knows his stuff, doesn't he? Now I I linked the research paper that he he co authored in the show notes, so you can all have a a look if you wish. Or am I the only one who likes to go back and look at the source research?

But that's our show for today and I hope you enjoyed listening to it. it was put together this week with the help of Dr. Euan McTurk. His contact detail details are in the show notes, and I'd like to thank him for his time.

If you've reached this part of the podcast and are still listening, thank you. Why not let me know you've got to this point by tweeting me at musingzv.bsky.social with the words solid state, hashtag if you know you know, nothing else. And thanks as always to my co-founder Simone. You know, he'd be lost without batteries. He really would. Brings out the pyromaniac in him. Which is frustrating with some of the current chemistries out there.

Dr Euan McTurk (: 36:53

I mean you can get them to catch fire if you are determined, but I can get my office desk to catch fire if I'm determined.

Gary Comerford (: 36:59

Thanks for listening. Bye bye now.