In-Situ Synthesis of Flexible Nanocellulose/Carbon Nanotube/Polypyrrole Hydrogels for High-Performance Solid-State Supercapacitors

Nanocellulose has become one of the most attractive matrix materials for flexible supercapacitors, owing to the high surface area, good mechanical properties and environmental friendliness. Herein, we developed electrode materials with high capacitance and mechanical flexibility through the in-situ synthesis of polypyrrole (PPy) in TEMPO-oxidized cellulose nanofibril (TOCN)/sulfonated carbon nanotubes (SCNT) composite hydrogels. The TOCN/SCNT/PPy composite hydrogels were thus obtained via a bifunctional Fe3+ in-situ oxidation, showing high specific capacitance of 5299 mF/cm2 at a current density of 1 mA/cm2. Furthermore, the assembled symmetric TOCN-40SCNT-PPy solid-state supercapacitor exhibited outstanding capacitance of 375 mF/cm2 and electrochemical stability with 163.2 % capacitance retention at a current density of 1 mA/cm2 for 2500 cycles. These nanocellulose/carbon nanotube/polypyrrole hydrogels are thus promising in the fields of flexible solid-state supercapacitor with superior electrochemical performance.