Layer-by-Layer assembled hybrid multilayer thin film electrodes based on transparent cellulose nanofibers paper for flexible supercapacitors applications

Cellulose nanofibers (CNFs) paper with low thermal expansion and electrolyte absorption properties is considered to be a good potential substrate for supercapacitors. Unlike traditional substrates, such as glass or plastic, CNFs paper saves surfaces pretreatment when Layer-by-Layer (LbL) assembly method is used. In this study, negatively charged graphene oxide (GO) nanosheets and poly(3,4-ethylenedioxythiophene: poly(styrene sulfonate)) (PEDOT:PSS) nanoparticles are deposited onto CNFs paper with positively charged polyaniline (PANI) nanowires as agents to prepare multilayer thin film electrodes, respectively. Due to the different nanostructures of reduced graphene oxide (RGO) and PEDOT:PSS, the microstructures of the electrodes are distinguishing. Our work demonstrate that CNFs paper/PANI/RGO electrode provides a more effective pathway for ion transport facilitation compared with CNFs paper/PANI/PEDOT:PSS electrode. The supercapacitor fabricated by CNFs/[PANI-RGO]₈ (S-PG-8) exhibits an excellent areal capacitance of 5.86 mF cm^-2 at a current density of 0.0043 mA cm^-2, and at the same current density the areal capacitance of the supercapacitor fabricated by CNFs/[PANI-PEDOT:PSS]₈ (S-PP-8) is 4.22 mF cm ^-2. S-PG-8 also exhibits good cyclic stability. This study provides a novel method using CNFs as substrate to prepare hybrid electrodes with diverse microstructures that are promising for future flexible supercapacitors.