From cotton to functional flexible transparent film for printable and flexible microsupercapacitor with strong bonding interface

Turning cotton into functional flexible transparent film is an essential step toward plentiful state-of-the-art applications. Herein, cotton is transformed into functional flexible transparent film by deconstructing macroscopic cotton fibers into nanometer-scale fibers and reconstructing the resulting fibers into a dense structure. The flexible transparent film also demonstrates excellent printability, swellability, degradability, and partially retained hydroxyl groups. Taking advantage of its excellent printability, text and QR-code are printed onto the film with high resolution. Taking advantage of its swellability and retained hydroxyl groups, a flexible rGO/CNT-based microsupercapacitor with strong bonding interface is directly fabricated on the transparent film, while avoiding the addition of insulating binders and exhibiting a thick electrode loading of 16.5 mu m. Owing to these unique characteristics, the flexible microsupercapacitor shows an ultrahigh areal capacitance of 39.1 mF cm(-2) at 0.5 mA cm(-2) and a high capacitance retention of 89.5% even under bending angles of 120 degrees. These superior characteristics of the cotton-derived functional flexible transparent film endow it strong advantages over plastic in the wearable device manufacturing and printing field.