Not an expert, but from what I read the expectation is for sodium ion batteries to get substantially cheaper than lithium, mainly due to material cost.
Lithium makes up 0.002% of the Earth's crust, meanwhile sodium is 2.36%, and there's quite a lot of it in the ocean.
The main downside is power density, which for grid storage is not as big a deal as it is for vehicles. But it will still be some years of research on sodium batteries for the cost advantage and manufacturing scale to materialize.
Lithium makes up 0.002% of the Earth's crust, meanwhile sodium is 2.36%, and there's quite a lot of it in the ocean.
https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
The main downside is power density, which for grid storage is not as big a deal as it is for vehicles. But it will still be some years of research on sodium batteries for the cost advantage and manufacturing scale to materialize.