Thanks Nando. I've seen the electrolyte described as 30% KOH with a little LiOH, though never a definition of "a little". When you say no lithium, do you mean not even as an additive, or don't use LiOH instead of KOH? The significance of LiOH as an additive is never made clear.
Thanks to other folks for the various inputs concerning products containing caustics, but something apparently important I've seen in the search is the need for "battery grade" chemicals. Evidently, non-graded chemicals may contain significant impurities that can cause problems in the battery, especially other metals. Battery grade is less pure than laboratory grade (and much cheaper), but better than industrial grade. This is just what I've found ... I don't know how much an issue it might be.
I don't know about other places, but where I live pretty much all the household products containing caustic use sodium hydroxide (cautic soda), rather than potassium. But I'd think any household product might be too impure to safely use in a battery. Maybe it would reduce capacity or shorten lifespan or such. But I'm just speculating here. I have NO experience in this area.