If we're going to do chemical-plant scale utility batteries, why not just lead-acid? It's well understood, simple, and the ingredients are cheap. Yes lead is toxic but it's easily contained and recyclable.
I think the very fact that PbS and for that matter NiFe have been around for decades and aren't widely deployed for utility scale probably counts against it. I suspect the answer may be that weight matters enough just in the cost of delivery to the site. Where utility scale storage is being deployed it's lithium; may switch to sodium as that crosses over in cost.
