Your estimation goes way off because you still believe lithium ion to be the only viable solution. By now Sodium-Ion batteries are already installed even in EVs and can be produced without any critical resource like lithium.

And then of course there are all the other storage solution. Like I said, there even are storage solutions like concrete balls. Successfully tested in 2016, here an article from 2013.

By now it wouldn't be wise to stifle this enormous emerging market of various technologies by using expensive, problematic technology (not just because the biggest producer of fuel rods is Russia).

The watthours is what gas is for. Germany's pipeline network alone, that's not including actual gas storage sites, can store three months of total energy usage.

...or at least that's the original plan, devised some 20 years ago, Fraunhofer worked it all out back then. It might be the case that banks of sodium batteries or whatnot are cheaper, but yeah lithium is probably not going to be it. Lithium's strength is energy density, both per volume and by weight, and neither is of concern for grid storage.

Imagine bridging even a short dunkelflaute of 2 days.

That's physically impossible for a place the size of Germany, much less Europe.

Another problem arises when you're generation 63.688 after today and still have to keep maintaining deadly waste from nations that don't exist anymore, because they produced "cheap" and "clean" energy for a couple of decades.
Come on, Jesus died like 2000 years ago, this stuff will haunt us for centuries. Arguing in favor of something this unpredictable is just selfish, stupid and shortsighted.