Comment by ggreer

19 hours ago

Which cell technology to use depends on the application. Tesla actually uses BYD blade batteries in some of their vehicles sold in Europe. The main issue with prismatic cells is that to be safe, they must be made with LFP chemistry, which hurts energy density. LFP is also worse at charging/discharging when cold, though battery management software mostly solves that.

Cylindrical cells make sense for higher performance NMC and NCA chemistries, as they can be cooled more easily (coolant lines can run in the voids between cylindrical cells), and any single cell failure is less likely to cascade to other cells. Batteries with cylindrical cells were easier to repair, but nowadays cells are welded together instead of bolted, so that's no longer an advantage.

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ggreer

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vel0city  18 hours ago

> 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.

  • ggreer  15 hours ago

    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.

    • vel0city  11 hours ago

      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.