Preparation And Capacitance Performance Of Wood-Based Nanofibrillated Cellulose Heterogeneous Composite Film

In this paper,wood-based nanofibrillated cellulose(NFC)was used as the matrix to fabricate supercapacitor electrode materials,and its potential in future green energy storage materials was utilized.Layered graphitic-phase carbon nitride(LGCN)was prepared by thermal polymerization-solvent etching method.The NFC/LGCN heterogeneous composite film electrode was prepared by vacuum-induced self-assembly method.The feasibility and capacitance performance of the heterogeneous composite film were preliminarily investigated.Based on the feasibility of NFC/LGCN heterogeneous recombination,wood-based nanofibrillated cellulose was functionally modified and the microstructure of the graphitic-phase carbon nitride was controlled to improve the capacitance performance.Preparation of wood-based nanofibrillated cellulose having a core-shell structure by in-situ polymerization and preferably an optimal core-shell structure as a matrix;Tubular graphitic-phase carbon nitride(TGCN)was prepared by solvothermal-thermal polymerization method.The core-shell NFC/TGCN heterogeneous composite film electrode was prepared by vacuum-induced self-assembly method.The samples were characterized by SEM,TEM,FTIR,XRD,XPS and BET.The NFC/LGCN and core-shell NFC/TGCN heterogeneous composite films were used as supercapacitor electrode for capacitive performance test,respectively.The conclusions of this research were as follows:(1)Preparation of NFC/LGCN heterogeneous composite film and preliminary study on capacitive performanceLayered graphitic-phase carbon nitride was prepared by thermal polymerization-solvent etching method using dicyandiamide as the main material and the mixture of isopropanol and deionized water as etchant.NFC/LGCN heterogeneous composite film with different LGCN content was then prepared using wood-based nanofibrillated cellulose suspension as the matrix by vacuum-induced self-assenbly and was used as the supercapacitor electrode.Compared with the NFC/40wt%LGCN heterogeneous composite film electrode and LGCN electrode,the results showed that the NFC/20wt%LGCN heterogeneous composite film electrode exhibited good capacitive performance,and the cyclic voltammetry curve of the NFC/20wt%LGCN heterogeneous composite film electrode exhibited a quasi-rectangular and the constant current charge and discharge curve exhibited a quasi-triangle.When the current density was 1 mA/cm2,the specific capacitance of NFC/20wt%LGCN heterogeneous composite film electrode was 51 F/g.After 2000 cycles of charge and discharge,the specific capacitance was 46 F/g,and the capacitance retention rate was 83.20%,which still remained high capacitance.(2)Preparation of core-shell NFC/TGCN heterogeneous composite film and study on capacitive performanceTubular graphitic-phase carbon nitride was prepared by solvothermal-thermal polymerization method using melamine as the main material and deionized water as the hydrothermal solvent.In the presence of FeCl3·6H2O,the core-shell wood-based nanofibrillated cellulose structure was constructed by polymerizing and grafting the conductive polymer polypyrrole(PPy)on the surface of wood-based nanofibrillated cellulose by in-situ polymerization.Compared with different polymerization time of PPy,the surface of wood-based nanofibrillated cellulose fiber bundle was uniformly wrapped by PPy at the polymerization time of 15 h,and the best core-shell structure was optimized.The core-shell NFC/TGCN heterogeneous composite film was prepared by vacuum-induced self-assembly method using the best core-shell wood-based nanofibrillated cellulose suspension as the matrix material and was used as the supercapacitor electrode.The results showed that the core-shell NFC/TGCN heterogeneous composite film electrode exhibited good capacitive performance,and its cyclic voltammetry curve was closer to a rectangle,and the constant current charge and discharge curve was closer to a triangle.When the current density was 5 mA/cm2,the specific capacitance and areal capacitance values of the core-shell NFC/TGCN heterogeneous composite film electrode were 157.95 F/g and 2.53 F/cm2,respectively.After 2000 cycles of charge and discharge,the specific capacitance and areal capacitance values were 146.25 F/g and 1.39 F/cm2,respectively,and the capacitance retention rates were 92.59%and 54.94%,respectively,which needed to be explored further.