I finally managed to do the initial carbon nanofiber experiments during July!
Just to heat the empty crucible to 730°C and keep the temperature there took me 15 trial-and-error iterations. I settled on induction heating, a steel pot on rock wool and ceramic chopsticks through which a fan contraption blew air through…
I even made a video out of one experiment.
A friend at a research institute was helpful enough to take a couple of SEM pictures of the resulting washed cathode product:
The pictures show curled up, around 1μm thick fibers similar to the ones published in the supplement for the “One-Pot Synthesis of Carbon Nanofibers from CO2” -paper that I used as a reference, where the electrolyte had had a lot of iron in it. This makes sense as I had used a steel pot instead of an alumina crucible…
Other things to try next time would be to bubble air into the electrolyte (lowers the concentration of lithium oxide), use cathodes with thicker surface layer of zinc and/or increase the duration of the initial low current step.
I hope I get the chance to soon experiment a bit more!