| Nanocellulose extracted from natural cellulose is a natural polymer material with high specific surface area,low density,high strength,and high elastic modulus.Moreover,it is ‘green' and almost inexhaustible.These advantages make lead to nanocellulose with broad application prospects in the field of electronic devices and energy storage devices.However,as an insulating material,nanocellulose cannot be directly used in electronic components or energy storage devices.Thus,improving the conductivity of nanocellulose-based materials has become an important issue.Compositing nanocellulose with conductive materials and carbonating nanocellulose are two main methods to solve the problems above.The composite of graphene and nanocellulose can not only effectively improve the electrical conductivity of nanocellulose matrix,but also fully utilize the structural characteristics of nanocellulose matrix to prevent the re-stacking effect due to van der Waals forces between graphene sheets.Herein,we used TEMPO-oxidized cellulose nanofibril(TOCN)as the matrix to composite with GO,RGO and pristine graphene(PG),which was stripped with triethanolamine,respectively.And we have conducted an in-depth study of the structure and electrical conductivity of the three kinds of composite films.Next,we prepared the TOCN/PG and TOCN/GO composite aerogels respectively and carbonized them.Then we used the two kinds of carbonized aerogels as the working electrodes to explore their application value in the field of supercapacitors.The specific work content and achievements are as follows:(1)TOCN/GO,TOCN/RGO and TOCN/PG composite films were prepared by casting method.FTIR,X-ray diffraction(XRD)and scanning electron microscopy(SEM)analysis showed that TOCNs were intercalated between the sheets of three kinds of graphene nanosheets through hydrogen bonding interaction,forming a special layered structure.The performance tests showed that the addition of three kinds of graphenes improved the thermal stability of the TOCN matrix.And the thermal stability increased with the increase of graphene content.When the amount of the three kinds of graphenes reaches 10%,the tensile strength,elastic modulus and elongation at break of the composite film all reached the maximum value.The conductivities of TOCN/PG composite films are the best,which reached up to 568 S/cm,whereas the TOCN/GO composite acted as an insulator.(2)TOCN/PG composite aerogels were prepared using TOCN and triethanolamine stripped graphene as precursors,and then carbonized under inert atmosphere at 750 °C and 1100 °C,respectively.Finally,carbonized TOCN/graphene was obtained and denoted as CTG-750 and CTG-1000,respectively.The structure of the carbonized composite aerogel was analyzed by SEM and other tests.All the results demonstrated that CTG-750 maintained a good three-dimensional pore structure.The electrochemical tests showed that the CTG10-750 had the largest specific capacity of 134.09 F/g,and the capacity retention rate was 98.89% after 5000 cycles.(3)The TOCN/GO composite aerogels were prepared using TOCN and GO as precursors,and then carbonized under inert gas conditions at 750 °C and 1100 °C,respectively,to prepare carbonized TOCN/RGO composite aerogels,denoted as CTRGO-750 and CTRGO-1100,respectively.SEM,BET and other tests show that both CTRGO-750 and CTRGO-1100 have a good three-dimensional network structure.Electrochemical analysis showed that the best electrochemical performance was achieved after incorporation of 10 wt% RGO.The specific capacity of CTRGO10-750 was 342.63 F/g,and the capacity retention rate was 98.89% after 10000 cycles.The specific capacity of CTRGO10-1100 reached 361.74 F/g and the capacity retention was 99.3% after 10000 cycles. |
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