What are the solvents that dissolve cellulose?

you have a few options. while not many things will dissolve cellulose, there are a few combinations that will work. Thiourea / NaOH seem to prevent aggregation, provided that the solution is not concentrated. another combination that you might want to look into is LiCl / DMF.

There might be other ion / solvent combinations that would work. a very harsh solvent is DMSO, so you might want to explore some other solvent ion combinations.