Lithium metal batteries with diluted high concentration electrolytes | Hacker News Reader

Lithium metal batteries with diluted high concentration electrolytes

dgist.ac.kr

24 pointsrustoo49 comments

Isn't diluted high-concentration electrolytes an oxymoron?

I read it like “OJ from concentrate”.

Homeopathic batteries

In this context, high concentration electrolytes have different chemical properties. https://onlinelibrary.wiley.com/doi/10.1002/sstr.202000122

Why can't we make liquid batteries yet, so you can tank "gel", discard the old gel through the bottom of the car at the "gas" station.

We can but my understanding is that there are issues, one of them being that these compounds are horrible things that you don’t want spilling or getting on people.

Any car tech has to pass what I call the “rusty pickup test.” It has to degrade gracefully and remain useful and safe enough for use.

Current EV tech passes that. I can totally picture a rusty old F-150 Lightning with aftermarket repairs.

Makes me wonder about how Teslas will age. IIRC they have lots of small batteries placed throughout the car and I’m not sure they were designed to be replaced after wearing out.

No, Teslas do not have batteries placed throughout the car. They have a single large battery pack that bolts to the underside of the car. Inside that are smaller battery packs that contain the cells as well as the cooling channels and electrical connections.

If you want to completely replace the batteries in a Tesla you can do so in less than an hour, if I recall correctly. It doesn’t require any special equipment either.

Does the Tesla battery come with electronic chips to prevent 3rd party batteries like inkjet printer cartridges?

No. But if you inject a new battery it needs to be mostly the same as the others and you need to re-balance the pack. There is software for this.

I've never heard of balancing batteries. All i could find about it was a forum post with people just as confused as me. [0]

Do you have resources on this topic?

[0] https://teslamotorsclub.com/tmc/threads/balancing-the-batter...

This video shows how it works and from there you might find some more information:

https://www.youtube.com/watch?v=T7Q0nNkQTC

Really about 5-6 min in.

It does not require specialized equipment, but it does require a lift --which few people have in their garage, and you have to remove all the seats. But to be fair, swapping out an ICE engine is even more work/difficult. On the other hand, one bad cell means you have to pull out the whole battery pack to replace the single deflective cell.

But the battery management system automatically disables bad cells so you wouldn’t need to replace an individual cell.

People seem to have a different experience. See here: https://electrek.co/2021/09/13/tesla-battery-pack-replacemen...

There are different models of Tesla packs in circulation.

That seems really unlikely, or impossible. The 18650 cells in a Tesla Model S are only about twice as big as an AA and they are grouped in parallel blocks that are then connected in series. There does not appear to be any way of isolating a specific cell.

Each module has six groups of cells in series, 74 in parallel in each group, giving a module voltage of 22.8 V.

See https://www.researchgate.net/figure/Tesla-Model-S-74p6s-Batt...

Newer Tesla batteries are fused per cell, so when a battery dies and it's neighbor cells start dumping charge into it the fuse goes and hopefully that's that. So it's perfectly possible for a single battery to become disconnected from the rest of the pack. But that's not a function of the battery management system, it's purely a safety feature (otherwise the pack would almost certainly go up).

You probably won’t be able to do the job in an hour without a lift, but you _can_ use just ordinary jacks. Certainly every car shop on the planet has the tools to do it; they won’t have to buy anything specialized from Tesla.

One Tesla tool they need —which Tesla released— is diagnostic sw to help ID the bad cell(s), else it would take longer to find a bad cell among ~1,500 of them.

Tesla just replaces whole packs now. They might have a tool to diagnose a bad battery but they don’t replace modules, they only replace entire packs.

As such their next gen pack is a single structural member of the car and likely will not be replaceable at all.

As I understand it, neither of those statements are exactly true.

Tesla replaces battery packs and then sends the old one back to the factory to be refurbished, rather than junked.

As for future designs, a structural battery pack would still be replaceable. The difference is that the battery pack would supply a portion of the strength and rigidity of the frame. That doesn’t mean the car would fall apart if you removed it, however.

That’s true if there are a small number of bad modules that you want to replace, but not really relevant if you’re just going to swap a new battery into an old Tesla.

I don’t know that you’ll be able to do that as they change to their structural batteries.

There are two: the main traction battery and a 12 V battery that keeps the control system alive even if the main battery is completely flat.

If we don’t want to have micro superfund sites, are we taxing EVs via refundable deposits sufficiently to ensure toxic metals are not left around?

GP is talking about hypothetical flow batteries, not vehicles in production.

> remain useful and safe enough for use. Current EV tech passes that.

Does it though? I heard exploding/self-burning batteries, which were a problem with some cellphones, were a much bigger problems with electric vehicles? I don't have data on how often it happens though, but that makes me skeptical.

It’s worth considering the status quo of ICE and gasoline fueled mechanical infrastructure which certainly has plenty of casualties and human health problems all throughout the lifecycle. In fact, early on I remember reading that people used to think cars should have only so much fuel in them because they are mobile bombs in people’s homes. But the dangers come from the emissions too and when gas tankers get in accidents and leak fuel into our environment.

Lithium batteries in consumer electronics are not really engineered for a ton of safety but for rapid time to market which is certainly not what I’d like to see for very long. And while shipping lithium batteries a warning label needs to be attached but shipping gasoline and lighter fluid requires special permits and must be transported isolated with certain guarantees by law.

In this respect our current market has deemed lithium batteries to be far safer than gasoline without much need for regulatory pressure to do so.

Gasoline fires happen all the time. They just don't make the news because they're not new. Like EV battery fires they are statistically rare. We got pretty good at handling incredibly toxic and flammable liquid fuels on a routine basis and we can do this for high energy density batteries too.

Stuff like that exists. They're called flow batteries. There are a few different chemistries, one on vanadium, another iron and a third on zinc bromide.

There’s a company called Redflow in Queensland, Australia that makes zinc bromide flow batteries.

[0]https://reneweconomy.com.au/redflow-in-running-to-deliver-it...

[1]https://twitter.com/redflowlimited/status/145896802782790042...

In some sense gas is like liquid non reusable battery … the chemical reaction of mixing it at high temperature with oxygen creates a lot of energy… the other output is co2 etc…

A gel in a liquid battery that deplete would presumably have some other outputs other then just pure energy since the mass of that gel is gotta go somewhere…

We can, but just charging when parked is better than that, and better than the old way with gas.

There's no real problem left to solve, but it will keep getting better as charging tech, infrastructure, cheap renewables and EV availability expands over time.

The real problem is the low energy density / high weight of the batteries (and as a result, of the whole car).

Also battery lifetimes. I'm in the market for another used car and thought it might be nice to have an EV, but batteries are only really good for 8-10 years and replacing them can be more than the vehicle is actually worth.

This might end up as non-issue because of economies of scale. In 10 years batteries might be so cheap that making replacement packs for older cars make sense.

On the other hand, there's non-negligible possibility that cars powered by ICEs will be forbidden to enter city centers in 10 years.

Nope, they may far longer than that when temperature-controlled (so, every car but two years of Leaf cars in Arizona). The only issue is new cars are so much better than earlier ones. They continue to work just fine.

They will still function if they have been under reasonable temperature control, but they will still undoubtedly lose capacity and therefore range. I have a 25mi commute each way and a 2012 Leaf bought today without a battery replacement seems like a pretty big gamble to me. Add to that that I live where winter weather is unkind and I am skeptical of how well old batteries would perform.

From my perspective, battery technology still hasn't proven itself in this regard.

Once you make batteries structural, the car actually is not that heavy anymore, combine that innovation with better batteries, cars will actually be lighter then they were.

I think maybe you meant to reply to someone else? I've mentioned nothing about weight.

Yes. Thanks.

Doesn't seem to be regarded as a big problem here in Norway where more than half of new car sales are already electric.

Once you make batteries structural, the car actually is not that heavy anymore, combine that innovation with better batteries, cars will actually be lighter then they were.

And even if it was more heavy, it improves driving since the weight is low and central.

We already do liquid batteries, like for example saltwater batteries, but they're for stationary use only - too clunky to carry around.

Power to weight ratio, in such systems, is very low, at current technologies.

For high density refuelable, IMO aluminium-air is your best bet.

https://news.ycombinator.com/item?id=21344135

https://nocamels.com/2012/06/new-cleantech-co-to-power-cars-...

An example of a pourable variant.

If you accept low efficiency, you can use thermal machines (max efficiency of roughly 35%), you can DIY such liquid battery : molten wax and a Stirling engine. Melt the wax to charge, and store in a thermos. You can use heat pumps to increase the efficiency by recovering wasted heat.

Plenty of things are technologically possible but as energy storage is commoditized so outside the lab we only care for the best ones where cost, efficiency, energy density, power density, energy leakage and battery life define the Pareto frontier.

There are flow batteries where you can switch the electrolytes when they are discharged.

You can also use standard lead-acid gel battery and switch them when they are discharged. (Use multiple small batteries and discharge them sequentially).

You can also switch solid-state Li-ion batteries.

There are also some molten metal and salts batteries : for example Ambri (https://ambri.com/technology/) (https://www.youtube.com/watch?v=m8751tkBU_Q) make some liquid metal battery ( where the discharged state is an alloy, and charging the battery separate back to its original components. Their batteries work at 500°C and are 80% efficient (vs lithium 95% efficient), and need to be immobile when used, but other can work at room temperature.

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