Posted by doener 22 hours ago
The right thing is to place the battery in a way that you don't have to worry abut the fire, not to expect a high-density battery to be perfectly safe.
The reason current Li-ion batteries are unsafe is that they contain a flammable electrolyte. There are batteries with higher energy density that have solid or semi-solid electrolytes. They’re so safe you should probably worry a lot more about driving your car than charging your battery.
Worrying about LFP or So-ion is probably also a waste of time.
I don't know what kind of chemistry shenanigans are going on to make that happen, but it's impressive.
CATL has demonstrated much better safety for their sodium EV batteries, but home and energy storage packs are more likely to be made of standard 18650 cells like the one in the video.
Tldr: while sodium thermal runaways are less dangerous than lithium, they are more likely to happen, and in particular charging a sodium battery to 100% SOC makes thermal runaway significantly more likely than in LFP batteries.
It's true that things like puncture or short circuit are much much less dangerous than with lithium. That is a big part of why the increased thermal runaway risk gets overlooked.
The main thing about LFP is people (stupidly) shove them in a basement or enclosed space because they are "safe".
But the "safe" part is that they outgas hydrogen when in thermal runaway, which, combined with enclosed spaces like basements (where people often have gas heaters or ....), is .... a super super bad idea.
Ironically, in this situation, sodium-ion is worse than LFP in almost every conceivable way - the gas is more flammable, toxic, etc.
People who think sodium-ion is "safer" are being sold a bill of goods.
There are many alternative materials for the cathodes of sodium-ion batteries and for now the industry has not settled on one of them as being the best.
The safety properties depend on the cathodic material. The vented gas can be toxic only for one class of materials (Prussian blue analogs) and IIRC none of the currently existing commercial sodium-ion batteries uses this kind of cathodes.
For the other cathode types, the vented gas is hydrogen exactly like in almost any kind of battery, and it is equally flammable for all kinds of batteries.
In the article linked above, the conclusion was that for one kind of cathodic materials, which perhaps is the one used in most currently existing sodium-ion batteries, the risk of damaging the battery by overcharging and the risk of thermal runaway (assuming that the battery management system fails to prevent these), are slightly higher than for LFP but lower than for other lithium-ion batteries.
On the other hand, mechanical damage by puncturing the batteries is less dangerous than for any lithium-ion batteries.
These conclusions are not definitive about sodium-ion batteries, because other cathodic materials will behave differently, and there is still a lot of experience to gain with sodium-ion batteries, so it is certain that the cathodic materials used in 2030 will not be the same as today.
The problem is charging the battery at negative, as this damages the internal structure. So you need to heat up the battery (aka, you discharge by warming up heating elements), until you hit the right point. And then you can charge up, what will create heat and thus allow for non-damaging charging.
Some even have a fun trick, where if your going to a EV station with your car (end point route on your build in sat nav). They can start to pre-drain the battery if its really too cold, to warm up the batteries even more. So by the time your at the charger, the batteries are on temperature. I forgot what brand did it that way, seen that feature years ago.
What is different is that Sodium-Ion batteries can charge from negative (i think it was -10°C), as they do not suffer from the same damaging effect.
Charging it at or around 0C will destroy it extremely rapidly due to electroplating of lithium.
Maybe you're right in terms of energy per volume. Sodium are very light weight in my experience.
The ratio of the stored charge per mass is 23/7 = about 3.3 times higher for lithium than for sodium (7 and 23 are the atomic masses of lithium and sodium), and the voltage can be higher by around 10% for lithium, leading to an even higher energy per mass ratio.
Nonetheless, both sodium and lithium are only a small fraction of the mass of lithium-ion batteries and sodium-ion batteries, so the difference in stored energy per mass is much smaller than for the pure metals.
In practice that means that today LFP batteries and sodium-ion batteries have about the same energy per mass ratio (and similar prices), with both having a lower specific energy than the more expensive NMC lithium-ion batteries.
For now, sodium-ion batteries are very new, so they are still a little more expensive than LFP, but eventually they will be significantly cheaper.
Already now, they have important advantages, so there are applications for which they are preferable even when still more expensive, e.g. where it must be possible to charge them at very low temperatures or where it must be possible to discharge them completely.
Not speaking one way or the other on sodium ion’s properties specifically. I see from sibling comments that it’s not straightforward.
It’s fundamentally a modeling exercise in the forward economic returns curve in the context of your energy needs. Lithium battery lease today as a power purchase agreement (potentially), and then swapping out for a purchased and owned sodium battery pack when the cost hits the right price. It’s always harder to predict the future the further out you attempt to predict, and this technology state of the art is moving very rapidly.
Byd dolphin, Thailand prices for above
Additionally, the original batteries were not sealed and required maintenance. Each battery has two ports which need to be filled individually. On top of those ports are supports/braces and wires in an already inconvenient space.
I'm so happy to not have to deal with refilling those batteries anymore. That alone made the conversion worth it to me. Also, lead-acid doesn't necessarily last longer. The new (LiFePO4) batteries have lasted about as long already and (knock on wood) seem to be doing fine. Maybe it's because I don't have to top them off with distilled water?
Tossed the lead-acid battery in my DR-Z400S motorbike, put a LiFePO4 in. The weight and mass placement difference was so significant that I had to re-set the suspension sag.
My DR-Z400S dual-sport motorcycle is like… 140kg?, kind of tall and narrow for a motorbike. The lead-acid battery is placed sort of high on a sort of fulcrumy point over the rear suspension. It's a very real difference. Didn't expect this dramatic a difference.
So having higher capacity 12V at the same size and only slightly more expensive might help?
I’m not familiar with BYD but yes you need some mechanical aptitude to change the 12v battery yourself.
Premature failure of 12V lead-acid batteries remains a persistent complaint among EV owners and is a recurring frustration. Just go to any EV forum. The traction battery will not top it off either when parked for extended periods.
Lithium batteries generally tolerate periods of inactivity better than lead-acid batteries. The OHMMU batteries are also “smart enabled”, see their website.
ALL the money that flew into "Fossil & Co" throughout the last, lets say, 50 or 60 years, including all implicit fundings, like state-building-streets or universities-masters-engineering-focus-ICE, all the money for lobbying, all the money for all the (counter)campaigns (from ALL sides), and all that money....
...WHAT IF we would have spent all of this money instead on Battery Research and all this Renewable Energy stuff?
Where would we be today on techdev curve? ;-) ;-)
“What If?” history is fun, but there are always Tradeoffs.
So in alternative world where oil would not be available coal will serve its role. The only big difference would be less geopolitical tensions as coal is much more evenly distributed.
And in yet another alternative where even coal is not available something like modern civilization will still be possible but the path to it will be entirely different.
This can be considered as the first method for extracting an almost pure chemical element from its compounds.
While in the beginning charcoal was used mainly for non-essential activities, like drawing, eventually charcoal was the reducing agent required for smelting metals from their minerals, first lead, then copper, then many others. Without charcoal, humans would have remained in the "stone age".
Without fossil coal, anything that is made from coal can be made from charcoal, except that this requires a lot of additional energy (for making first the charcoal; but with modern technology it is not necessary to pass through charcoal; carbon dioxide can be reduced to substances like methanol or formaldehyde or passing through syngas to hydrocarbons, which can feed other chemical processes).
Ungodly amount of money was spent on battery research since 1945, at least $100-150B since 2000 alone. Every combination of anode, cathode and electrolyte was tried, tested and evaluated. We got silver-zinc, Ni-Cd, NiMH and finally Li-Ion batteries as the result.
https://www.iea.org/commentaries/the-rise-of-lithium-ion-bat...
Early Li-ion battery tech was developed by none other than Exxon itself (in second link)
I cant believe this esp. since CATL is reporting on a regular base new innovations. Im a layman here but if I think about the 3-digit amount of USD that Europe alone is spending on imports of oil, it seems unlikely that this money couldnt be spent on research batteries?
Same with solar: 20 years ago, 1 Wp was about 3-5 EUR, today its 7ct. This wouldnt have been possible if research wouldnt have been massivly accelerted.
Dramatic improvements in battery capacity and durability require big material science breakthrough and those may come from unexpected directions (i.e. optimizing ICE engines, as mentioned.)
I mean, batteries and solar panels are cool, but thinking about the future doesn't mean we should forget the present. The advance we could have gotten by diverting funding away from fossil fuels and towards renewables and batteries is to balance with the damage caused by using outdated fossil fuel technology before the transition.
Cities are breathable now thanks to all the progresses modern engines have made. They will be even more breathable with zero emission cars, but I prefer to wait a bit more in these conditions than waiting a bit less in a smog filled city.
Batteries are only a part of the equation. Practical EVs were enabled not just by Li-ion batteries but by IGBTs. And semiconductor development moved about as fast as possible.
And then there's a gulf between lead-acid batteries and Li-ions. I think only NiMH batteries would have been a reasonable midpoint, and even they would have been impractical for full EVs.
Most of this is destined for stationary storage that would likely have used lithium-based chemistry instead, or not been built-out at all. Every GWh of capacity sodium offsets is a GWh that isn't supplied by lithium, so demand for higher-value battery chemistry should be lower, and take prices with it. Good news all around.
LFP and NMC are, sadly: ubiquitous, dangerous, and normalized. LFP entering thermal runaway produce hydrogen gas that requires continuous igniters to burn off and burns/smolders for days to weeks.
Just remember, the most frequent cause (by far) for fire trucks to get called out is vehicle fires. Whatever you may think of battery safety, if you are fine with being in or around a fuel bomb on wheels and still worry about battery fires, you might be a bit confused about risk assessment. EV fires make the news. Petrol cars on fire generally don't because it's such a common event.
Most modern LFP batteries are actually pretty hard to set fire to. It's something battery makers exploit by subjecting their batteries to all sorts of abuse (shooting them, hammering nails through them, throwing them off buildings, etc.) to demonstrate how safe they are. Whereas a petrol car fires can (and frequently do) result in people dying. Combustible fuel just isn't designed to not combust.
Cars burning is a popular plot point in movies. Probably not that realistic but they burn so pretty. A slowly smoldering Tesla is a lot less exciting. In general, EVs are underused in action movies even though they'd be a lot better performing in a car chase. Petrol cars are much more dramatic. They make noise. They explode. They struggle to start when they need to or when it is cold. Or they run out of fuel and stutter to a halt. Or you set them on fire to dispose of a body. Easy success for a director. Realism in movies is of course not a thing. But exploding Teslas is a bit of a hard sell.