I wonder if we will run out of battery materials in a hundred years, then what?

Are we burning the battery materials into gases and sending the results into the atmosphere? No, then we are unlikely to run out of materials on a primary or secondary, recycled, basis. Not to mention the diversity of choices available for chemistries and storage

we might end up switching to sodium batteries for the grid, they’re heavier so not great for cars, but otherwise they’re fine

Impossible as there are so many chemistries, but hopefully we don't run out of water for pumped hydro.

If we run out of Saltwater then we have very different problems at our hand.

1. Sodium batteries 2. Kinetic Batteries

Global scale HVDC networks could eliminate a significant part of the storage requirement.

It is far more likely to run out of practical fissile materials than it would be to run out of electrochemical materials.

green gas or flow batteries