Biomass-derived cellulose nanofibrils membrane from rice straw as sustainable separator for high performance supercapacitor

Biopolymer membranes derived from biomass have drawn considerable attention due to their vital role in the protection of environment and electrochemical performance of supercapacitors (SC). Herein, a simple and cost-effective solution casting method is applied to prepare cellulose nanofibrils (CNF) membranes, with different thicknesses, from agricultural rice straw waste, and then used as supercapacitor separators. Among the fabricated membranes, CNF membranes with 30 mu m (CNF 30) thickness have a porosity of 51 %, electrolyte uptake of 225 % and the highest mesopore (17.2 %) with uniform pore size distribution. The supercapacitors, with CNF 30 as supercapacitor separator (CNF 30-SC), exhibited the highest specific capacitance, energy density and power density of 150.7 F g(-1), 30.2 Wh Kg(-1) and 240.0 W Kg(-1), respectively, at a current density of 0.1 A g(-1). These results were 1.2-1.5 times higher than that of supercapacitor with commercial membrane (CS 30) separator. CNF 30-SC showed excellent electrochemical stability after 5000 cycles; the capacity retention and coulombic efficiency were 100 %, whereas commercial CS 30 showed 86.5 % and 97 % efficiency, respectively. These results demonstrated that CNF 30 membrane from rice straw can be a good alternative to commercial membrane for high-performance supercapacitor devices.

Automated summary

The cellulose nanofibrils (CNF) membranes derived from rice straw showed superior performance as supercapacitor separators, exhibiting higher porosity and electrolyte uptake, as well as increased specific capacitance, energy density, power density, excellent cyclic stability, and coulombic efficiency compared to commercial membranes.