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Comment by vel0city | Hacker News Reader

> The main issue with prismatic cells is that to be safe, they must be made with LFP chemistry, which hurts energy density

This is obviously untrue. Tons of other chemistries have used prismatic cells with good safety as well. You think Macbooks and iPhones use LFP or cylinder cells?

> Batteries with cylindrical cells were easier to repair,

It can be just as easy to repair a prismatic battery as a cylinder battery. It all comes down to the layout of the battery. And as you mentioned, how the battery is constructed, if the battery is structural, etc.

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Since this is a discussion about electric vehicles, I thought it could go without saying that I was talking about batteries in such vehicles, not batteries in consumer electronics that are 1,000 times smaller.

To use an analogy: If someone stores a gallon of gasoline in a single-walled plastic container, that's probably OK. But storing 1,000 gallons of gasoline without certain safety measures is unsafe. So it goes with battery capacities.

But it still is untrue even in the discussion of electric vehicles. Tons of EVs have been made safely with chemistries other than LFP with prismatic cells. In fact most non-LFP EV batteries are pouch or prismatic, not cylinder.

This isn’t true: “most” non-lfp batteries in EV context are Tesla. Which means they are cylindrical.

Or are you counting OEMs rather than actual vehicles?

Apart from Tesla very few EVs ever used cylindrical cells.

But that's usually just the packaging... if you open that up you'll find... cylindrical cells

No?

BMW is moving the other way, from prismatic cells to cylindrical

https://phdenergy.com/beyond-teslas-4680-why-bmws-gen6-4695-...

My point was about cylindrical cells with higher energy chemistries like NMC and NCA. Rivian uses cylindrical cells for their non-LFP batteries. Lucid uses 2170 cells. As far as I can tell, those three (Tesla, Rivian, Lucid) are the only US car manufacturers who have not had battery recalls due to fire risk.

GM, Hyundai, and Nissan all used pouch cells with higher energy density chemistries, and had recalls due to battery fire risks. Ford also recalled tens of thousands of their plug in hybrids due to battery fire risks, though they haven't found a solution yet beyond limiting the max charge of the battery. These batteries are also NMC pouch cells.

I'm sure it's physically possible to make safe, reliable pouch or prismatic cells using higher energy chemistries, but so far it has been risky for those who have tried.

> You think Macbooks and iPhones use LFP or cylinder cells?

https://old.reddit.com/r/spicypillows/

And I can find tons of videos of cylindrical cells catching fire and exploding. What's your point exactly?

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