Why CATL and BYD Are STILL Betting on Sodium-Ion Batteries.

You’ve had earnest opinions about sodium-ion batteries from all the usual suspects here on YouTube recently, haven’t you? Including me of course! Will sodium-ion replace lithium-ion? Is it really any better? Was the initial surge in public awareness and corporate R&D expenditure ONLY down to huge lithium price hikes after COVID? Did the subsequent lithium price crash kill off the sodium-ion dream completely, or does the latest lithium price uplift mean another recovery for sodium chemistry? Will solid state batteries eventually put paid to both those chemistries anyway? And is some random bloke from Finland with a questionable facial hair strategy about to smash up the entire battery market with a product that is apparently made of moondust and unicorn tears. Who knows, eh? Well, I’ve got a reasonably good idea about that last one, but what we do know for sure is that in the real world of periodic tables and battery chemistries, some things can’t be changed. For example, sodium IS a bigger atom than lithium. It’s heavier than lithium and it’s generally accepted that its ions moves more slowly across conventional electrolytes and are more difficult to shoehorn into an electrode material on the other side. Conclusion – Sodium -ion chemistry will NEVER challenge lithium-ion in high energy density mobility applications like cars and trucks. Claxon from family fortunes Right stats. WRONG conclusion! Because, at least according to two new independently operating research teams, even those limitations can apparently now be easily overcome. Ooh, there’s never a dull moment for a battery chemist is there? Hello and welcome to Just have a think Lithium battery chemists have spent about the last three decades grappling their technology up to the lofty position of undisputed king of batteries, haven’t they? They’re in just about everything we call useful in our modern world. Maybe we should insert some into our politicians as well to make them a bit more useful. Just a thought. Anyway, I digress. The point is sodium-ion batteries are usually framed as a sort poor-man’s alternative to lithium-ion. Because sodium-ions are relatively large compared to lithium-ions, they don’t do that nice intercalation thing inside graphite that lithium ions are so good at. So, a different material has to be used for sodium-ion battery anodes, and at least up until now anyway that’s resulted in lower performance and lower energy density. Fine for stationary energy storage… but heaven forfend that we should see sodium-ion bespoiling a high-performance electric vehicle. Which is a shame because sodium is very cheap and very plentiful with none of the ethical or geopolitical sourcing issues of its apparently higher performing periodic table neighbour. And yet, China’s two biggest battery players, CATL and BYD, are now openly fast-tracking sodium-ion batteries. CATL’s sodium-ion cells are reportedly ALREADY crossing the metaphorical Rubicon into passenger vehicles. And this is happening at the same time that lithium prices are once again reminding everyone how volatile and geopolitically awkward that supply chain really is. So, what’s changing then, because companies like these don’t pivot their battery strategies on a whim. The answer, as it turns out, is NOT that sodium itself, as an element, suddenly got intrinsically better. It’s more that chemists have finally stopped blaming sodium for cell related problems that weren’t actually its fault. What ARE you wittering on about Dave? Well, I’ll tell you, but before I do, I’m very much hoping to persuade you to take a couple of seconds to click the like and subscribe buttons just down here. That simple action really does help this channel survive in a sea of reaction thumbnails and shouty nonsense, and it means more of you end up seeing future videos like this one, made by real human beings. If you’ve already subscribed then bless your darling heart, and if you haven’t yet subscribed then you really would be making my day if you could. Anyway, where were we? Yes, so the traditional story goes a bit like this. Lithium ions are small and nimble. Sodium ions are bigger and cumbersome. So lithium moves faster, diffuses faster, reacts faster, and charges faster. All sounds fairly straightforward and intuitive, doesn’t it? But it turns out what REALLY limits how fast a battery charges or discharges isn’t just down to the dynamics of the ions themselves. It’s the entire environment those ions are forced to move through. Which brings us nicely to this research paper, published in December twenty-twenty-five in the Chemical Science journal of the Royal Society of Chemistry. A paper that for once does NOT come from a Chinese research facility but from the Tokyo University of Science in Japan. Hard carbon, which is typically used as the anode for sodium-ion batteries, behaves in a different way to graphite, which is what most lithium-ion battery anodes are made of. Instead of the neat intercalation process that we’ve looked at in several previous videos, sodium ions slip fairly easily into tiny gaps and defects in the carbon structure and insert between disordered graphene layers. At lower voltages

sodium also collects inside extremely small pores, bunching together in clusters that start to look a lot like pure sodium metal. And when batteries struggle to charge quickly or lose capacity, we tend to blame the chemistry, when in reality we may just be watching a traffic jam. To overcome that limitation, the authors of this new research propose a deceptively simple idea called the ‘diluted electrode method’. And it kind of means just what it says - instead of packing active particles tightly together, the researchers diluted them. Particles of hard carbon are embedded in electrochemically inert aluminium oxide and spaced far apart inside that material matrix. That means there’s plenty of electrolyte and there’s plenty of ions. To keep everything electrochemically connected, the researchers employed conductive carbon nanotubes, because no self-respecting new battery breakthrough is complete these days without the old carbon nanotubes, is it? The result is none of the so-called ion starvation that has beset other chemistries in the past, but also no electrode-scale bottlenecks. And that meant the sodium ions were much freer to move and rearrange themselves efficiently. What these researchers are trying to tell us here is that sodium itself is NOT the real problem. The problem so far has been that the way electrodes are built and flooded with electrolyte has been the limiting factor. Once that’s fixed, sodium behaves far better than most people expected. Multiple tests showed that the sodium insertion, or sodiation rate in this amended hard carbon substrate is higher than lithium insertion, or lithiation into the same material. In fact, results suggest that sodiation into the diluted Hard Carbon electrode can happen at a rate comparable to lithium-ion intercalation in GRAPHITE electrodes. Hard carbon is still a tricky material to work with though because the electrode architecture is still doing damage. Hard carbon is full of nanopores. And when liquid electrolyte floods those pores during manufacture, bad things happen. Solvent molecules decompose. Side reactions consume charge. Useful empty spaces get filled up, and the crucial first-cycle efficiency can collapse. That process only stops once a stable film has formed on the anode that protects it from further decomposition by the electrolyte but also consumes some of the storable energy. 7:29 That problem hardly ever occurs in lithium-ion batteries because the protective layer forms more easily on dense graphite anodes. 7:38 If only a protective layer could be persuaded to form on a hard carbon anode as easily as it does on a graphite anode, I hear you exclaim. There’s no flies on you is there! That’s a challenge taken up by the authors of a SECOND piece of recent research. This one comes from the Federal Institute for Materials Research and Testing in Germany. The approach here is rather than changing the hard carbon itself, how about adding a thin layer of activated carbon around it. Not so thick that it adds too much weight. Not a structural thing. Just enough to act as a filter. It’s a material that Sodium ions can pass through easily. But bulky solvent molecules largely can’t. That means the pores inside the hard carbon stay accessible to sodium without being poisoned by the dreaded electrolyte decomposition. And the results have been very encouraging indeed. First-cycle efficiency jumped dramatically. Usable cell capacity increased. And battery performance started to look much more like what the intrinsic physics of sodium-ion predicted in the first place. It’s not magic, it’s just a bit of lateral thinking to get all the electrochemical ducks lined up nicely. Turns out the chemistry was already perfectly capable of performing as well as lithium, it was just the engineering that was a bit wonky. So, if sodium can genuinely charge quickly, tolerate cold better, offer far less risk of thermal runaway and avoid the supply-chain headaches of lithium, then you’ve got a bit of a genuine market disruptor on your hands, haven’t you? At least while we wait for the solid-state battery mirage to become a reality anyway. Or maybe all cars will just be powered by nuclear fusion by the end of the decade, eh? Which will be useful because apparently, we’ll all be living on Mars by then, won’t we? Sorry…just got myself into a bit of a cynicism loop there. Back in the real world of actual achievable engineering, CATL has now confirmed that its sodium-ion batteries are entering passenger vehicles. Not as lab demonstrations — as real products. BYD, meanwhile, is accelerating sodium-ion development as lithium prices surge again. And what’s driving this is not just cost and not just geopolitics. It’s the fact that sodium-ion performance, even without the two obvious improvements we’ve looked at today, has already quietly crossed a threshold from “interesting” to “useful”. Maybe only for smaller vehicles at the moment, but it surely won’t be long before these additional steps are built into real-world production battery cells, and we start seeing sodium-ion make a dent in the high-performance electric vehicle market. And

let’s not forget sodium-ion is already better in cold climates and already very attractive in cost-sensitive sectors. It’ll probably never replace lithium-ion completely, but it definitely looks like it’s going to carve out space where most analysts said it could never compete. It’s a pattern you see again and again in energy technology. Everyone assumes they’re limited by the material, when in many cases, we just haven’t worked out how to properly engineer the system around it yet. We might not need a bunch of spangly new technologies to make the energy transition work. We’ve almost certainly got everything we need already. We just need to apply a bit of lateral thinking, as my childhood hero Edward de Bono would say, and get on with the task of optimising for performance. Let me know what you think in the comments section below, but that’s it for this week. Thanks, as always, to the amazing group of people over at Patreon dot com forward slash just have a think, who enable me to keep ads and sponsorship messages out of all my videos. Don’t forget to like and subscribe to help get us to our next target of seven hundred thousand subscribers. And most important of all, Thanks for watching this far. It’s very much appreciated. Have a great week, and remember to Just Have a Think