On the one hand, I think it's sensible to assume we'll find something better or more suitable, but in the other hand, we're dealing with fundamental physics, no

On the one hand, I think it's sensible to assume we'll find something better or more suitable, but in the other hand, we're dealing with fundamental physics, not consumer preference or any sort of abstraction away from function. To produce food, we will need carbon. Structural materials will likely be steel or iron alloys. Energy storage works best with lithium for practical engineering reasons, and it's highly unlikely some other element will replace it. The advantage of basic, high availability elements is you can pick up the raw material and process it almost anywhere. The distribution of elements is predictable, so unless you have a huge supply of unobtainium, it's better to use things you can scrounge on the way to or where you're going. In a multi-species interstellar civilization, it's also reasonable to think that other starfaring technology will share similarity with your own - having a stockpile of lithium might mean you have a basic trade good.