Study Of Supercapacitor Based On NFC-RGO-PANI Composite Electrode

Supercapacitor with fast charging and discharging,high power density,long cycle life,etc,presents a great application prospect.As the new 2D material with the sp2 structure,graphene becomes the most common electroactive material of supercapacitor because of excellent conductivity and huge surface areas.Cellulose is the most abundant resources with green recycling.1D amphiphilic Nanocellulose(NFC)can disperse 2D and nano materials and expected to mix graphene and polyaniline(PANI)to prepare a well-dispersed aqueous suspension in order to the restack between the electroactive materials to prepare flexible NFC composite supercapacitor with uniform structure and extend the application of cellulose materials in the field of energy.In this study,L-ascorbic(LAA)acid and tea polyphenols(TP)was first unilized as the reductant of graphene oxide(GO)and the synergy between LAA and TP was studied in order to prepare reduced graphene oxide(RGO)with great conductivity.Adopting the study of NFC as the dispersant of RGO and PANI,we utilized vacuum filtration and freeze-drying methods to prepare NFC composite paper and aerogel electrode materials to assemble NFC composite paper and aerogel supercapacitirs.In the process,the influence of composite ratio,the carboxyl content of NFC and the freezing temperature to the structure,mechanical property,conductivity and electrochemical performance were also studied.Here are the resreach contents and the results in details:1.Adopting LAA as the reductant to prepare RGO,the influence of reaction time,LAA/GO ratio and temperature to the performance of RGO were studied.The results show that the optimal conditions is reaction time is 8 h,LAA/GO ratio is 1:4 and temperature is 75℃.The conductivity of the prepared RGO film is 820 S/m.2.Adopting LAA/TP as the reductant to prepare RGO,the synergy between LAA and TP was studied.Compared with single reductant LAA,when reaction time is 8 h,temperature is 75℃ and GO:LAA:TP ratio is 1:3:1,the conducitivy of RGO film was improved from 820 to 1308 S/m.The maximum width of prepared RGO-LAA/TP is about 1 μm and the thickness is about 0.923 nm,which suggest the graphene is single structure.3.The dispersing influence fo NFC to RGP and PANI were discussed.The stable and welldispered suspersion of NFC,RGO and PANI can be prepared when NFC:RGO=5:3 or NFC:RGO:PANI=5:3:3.Adopting the max dispersing concentration of RGO in NFC dispersion(4 mg/mL)is 2.4 mg/m L,the max dispersing concentration of PANI is 2.4 mg/m L.4.Utilizing vacuum filtration method to prepare NFC composite paper electrode materials(NR and NRP)and the influence of composite ratio and the carboxyl content of NFC to the mechanical performance and conductivity.As the increasing of the RGO ratio,elastic modulus and conductivity of NR paper electrode increased firstly and then decreased.When NFC:RGO=5:3,the max elastic modulus of NR53 paper electrode is 12.18 GPa and the conductivity is 59 S/m.The addition of PANI can improve the conductivity of NRP paper electrode to 69 S/m but elastic modulus decreased to 10.12 GPa.In addition,with the increasing of the carboxyal content of NFC,the elastic modulus and conductivity are on the rise.The assembled NRS and NRPS supercapacitors exhibit excellent electrodchemical performance.When the current density is 0.5 A/g,the specific capacitance of NRS supercacitor is and NRPS supercapacitor with PANI exhibit 305 F/g,which suggest the electrochemical performance improved by 64.8%.5.Utilizing freeze-drying method to prepare NFC composite aerogel electrode materials.The results show that the number of pore in NFC composite aerogel increase and the pore size was decreased with the surface aerea and conductivity inproved with the increasing the RP ratio and the carboxyl content of NFC.However,the improvement of freezing temperature presents a negative influence on the pore structure and the conductivity of NFC composite aerogel.When the freezing temperature is-40℃,RP ratio is 50% and the carboxyl content is 1.69 mmol/g,the pore size of are mainly distributed in 2.3 nm and the surface area of NFC composite aerogel is 155.8 m2/g and the conductivity is 92 S/m.6.The improvement of RP ratio and NFC carboxyle content and the decreasing of the freezing temperature can enhance the surface area of NFC composite aerogel to enlarge the area wetted by electrolyte of RGO and PANI to achieve well electrochemical performance.When the freezing temperature is-40℃,RP ratio is 50% and the carboxyl content is 1.69 mmol/g,the NFC composite aerogel supercapacitor exhibit the best specific capacitance was 402 F/g(the current density is 0.5 A/g).What’s more,NFC composite aerogel supercapacitor exhibit excellent flexible mechanical performance and good cycle stability.The capacitance retention of NFC composite aerogel supercapacitor is 98.13% after 1000 charge-discharge cycles.