This sounds feasible. I know next to nothing about chemistry and yet your discussion made sense to me. What I kept thinking about was the relative environmental impact. I know I've read before about the cost (environmentally) of mining material for batteries. This is the downside of renewable energy. Here's an article that talks about the cost, human and environmental, of mining cobalt.
How does a sodium battery stack up against this? It's less rare, but does that mean it is lost costly (in environmental and human terms) to extract. And also, is there a disposal issue?
Thanks. Great article.