>>282103466
That probably the best way to store them unless you want to do uva/uvb blocking museum grade frames to hang them. I replaced my windows this year with UV blocking windows and I works nights so the only thing I have to worry about is humidity.
Is each cel a single or multiple? If multiple you can do lining sheets in between. I use museum grade acid free watercolor for Matts and backing.

I bought damaged so that I knew were damaged with vinegar syndrome so for those I keep them in a big frame. I only buy cells that I want to put in frames I don't keep anything in a folio