Indeed. Nant have been talking $100/kWh all in which is cheap but I think that's projected rather than that you can actually buy them for anything like that. Though the material cost is interesting as a potential end point if you got super automated production. A problem with Vanadium flow for example is that the materials are like 60% of the cost of the battery so it's hard to drop much. With LiCo the materials are quite a big % of the battery cost though these things vary with time and may drop. I think Telsa are reducing the amount of Cobalt used dramatically for example https://qnovo.com/82-the-cost-components-of-a-battery/
Sodium ion batteries that don't use much in the way of exotic materials seem feasible. It's the sort of thing where someone has to be successfully selling them to prove that they are reasonably competitive though.
Pretty much all of the standard electrode potentials are like a volt or two. You aren't going to find a room-temperature molecular chemistry that gives you 10 or 100 electron volts of energy per atom. Lithium is pretty much the extreme there.
The cost of the raw materials is more interesting with flow batteries, where you can imagine adding big tanks containing the electrolytes without adding more cells.
It still comes down to the cost per unit of energy stored. If the electrolyte is a mediocre storage medium with low costs, it may not be competitive with an excellent storage medium with moderate costs, even after increased manufacturing costs.
Sulfur-based flow batteries are supposed to be very cheap in principle, with the active chemicals costing around $1/kWh. Of course all these lab technologies face a perilous journey to the market.
"The total cost of materials is $0.1 per watt-hour"
Or presumably $100/kWh
On the other hand with Zinc Air "our fundamental raw material cost of zinc is just $2-$3/KWh." from https://www.altenergymag.com/article/2019/03/zinc-air-batter... talking about NantEnergy's rechargables.