Unfortunately lithium is becoming increasingly difficult to obtain at scale. If graphite becomes commercially viable, that might be a good step up since Carbon is freaking everywhere.
Lithium reserves are more than 100x annual global production. Estimate lithium resources are something like 600x annual global production. There is no shortage of lithium, although there are temporary bottlenecks as capacity ramps up.
https://www.maltainc.com/our-solution
There's various prototypes in testing but at least for short term storage I think lithium batteries continual price drop is leading the pack.