> I mean when you get a rate that high, it seems like it must be just a relatively heavy element, and a metal, like Gold, and relatively unreactive (just carrying ions and such).
This is the opposite of the truth. Lithium is not dense at all (~.53g/cm^3), especially for a metal, and as a Group 1 metal is extroardinarily reactive - if you cut lithium it will oxidize as you watch, and if you expose it to water is will explode into flaming chunks.
> I imagine they don't get to 100% because they just don't bother to heat it high enough to melt things in there with a ridiculously high melting point and risk creative copper fumes and whatnot (from some metals evaporating). i.e. it's still easy, they just don't want to.
No. Lithium has a very low melting point (roughly 180C/355F).
Furthermore, your contention that a process with an efficiency of 93% should be easy to bring to 100% is so off base I don't even know where to begin. Squeezing out the last few percentage points is the hardest part!
My chemistry is very bad, but that seems to be in 3M HCl with added H2O2 at 80°C. Combining that mix with Lithium batteries, to me, sounds like a process that may be difficult to safely scale up from the lab.
