I'm going to copy this comment I saw on slashdot re: this yesterday that seemed to let some of the air out of the whole press release:

"The salt mentioned is not table salt, but lithium chloride. Lithium chloride - which makes up a half by weight of the film, and is also in obvious demand for batteries, is $70/kg or so in bulk."

I haven't really dug in deep myself, but this is the comment that deflated me when reading about this yesterday, so worth looking into at least imo