Cellulose films of approximately 5 mm thickness, reconstituted from ionic liquid media onto a poly-ethylene-terephthalate (PET) film with a 5, 10, 20, or 40 mm diameter microhole, show current rectification when immersed in aqueous NaCl. For “asymmetric cellulose deposits” this rectification, or ionic diode behaviour, is then investigated as a function of ionic strength and microhole diameter. Future applications are envisaged in sustainable cellulose-based desalination, sensing, or energy harvesting processes