I feel like it's unlikely for pack prices to continue to drop 21%/year. Tesla+Panasonic have gotten pretty good at reducing pack costs, and while Tesla's in-house cells could reduce costs significantly, IIRC, a 21%/year reduction in costs for a decade would be significantly less than the materials cost.

I didn't mean cost strictly in the monetary sense.

The battery in a BEV accounts for a substantial portion of the resources involved in its manufacture. The battery forms basically half the mass of the entire vehicle, and we're not talking about a sack of unprocessed dirt here. If it has usable life left for energy storage purposes as-is, we should absolutely take advantage of it.

The decision on whether to reuse or recycle should be informed by lifecycle analyses of the costs and externalities of both options. Maintenance isn't free of externalities and it will presumably be much higher in a system made up of older batteries. The opportunity costs shouldn't be entirely dismissed either - lower hanging fruit for removing emissions may be available elsewhere.

For Tesla's the battery pack is about 1/4 of the vehicle's weight. The battery pack weighs around 500Kg and the car is around 2,000Kg, depending on the model. The main problem as EV manufacturers look to shave weight the batteries are going to become more integrated into the car's structure, which is going to make them harder to remove and reuse the cells at the end of the car's life.

Do you have any examples of designs where batteries are literally integrated into vehicle structure?

The iconic Tesla battery-skate design is still modular/replaceable for example (they're all 18650/2170/etc cells).

Individual cells might in theory be modular, but Tesla for example is gluing them to their battery packs which makes them much harder to reuse at the individual cell levels. The battery pack it’s self is becoming a structural element though it can still be removed, but unfortunately it’s proprietary.

On top of this EV batteries are getting very close to lasting the normal lifetime of the vehicle. Car manufacturers are likely to tray and leverage this as a form of built in obsolescence by making replacing the battery unappealing under normal usage patterns.

Here's some pictures of Tesla's plans for it's battery pack:

https://electrek.co/2021/01/19/tesla-structural-battery-pack...

In that article it specifically mentions the cells being "bound" (their words not mine) into the honeycomb pack.

> The main problem as EV manufacturers look to shave weight the batteries are going to become more integrated into the car's structure

For those looking for a source, here's Elon Musk saying exactly that to Sandy Munro.

https://youtu.be/YAtLTLiqNwg?t=1335