Fabrication Of Flexible Carbon Nanofibers For High-performance Supercapacitor Electrodes

Recently,supercapacitors have been center of attention for scientists as potential energy storage material for the generation of new devices.Tremendous efforts have been involved to improve their performance with no compromise on their energy and power density.For this purpose,two issues need to be resolved: first,to design effective strategy for developing flexible high performance electrode materials.Second,to design appropriate assembly supercapacitors i.e.symmetric or asymmetric supercapacitors.In this thesis,recent research and development regarding flexible and high performance supercapacitors along with theoretical background has been summarized,certain influencing factors,challenges,and perspectives have also been thoroughly discussed.Additionally,current work offers an ultimate intuition and a pathway for designing next-generation flexible supercapacitors especially from carbonaceous materials?carbon nanofibers?for various commercial applications.The main contents of the thesis are below:1.Herein,we first developed an effective technique for the regulated fabrication of mechanically robust and flexible hybrid membrane with combination of Co₃O₄ nanoparticles?NPs?and carbon nanofibers?CNFs?.The quantitative pore size distribution and fractal analysis revealed that developed membrane possesses tunable porous structure and a high surface area i.e.483 m2/g.Moreover,hybrid membrane fabricated via this technique offers as high as 911 F/g at 5 m V/s with 76% retention over 1000 cycles in 1 M H₂SO₄ solution.These highly flexible and cost effective fabrication technique paves new insights into the development of lightweight flexible supercapacitors electrodes in future energy storage materials.2.To present the composite CNFs we fabricated highly flexible structures by combining nickel cobaltite,carbon nanotubes and CNFs?NiCo₂O₄/CNTs CNFs?with regulated mesopores by electrospinning and subsequent carbonization technique.The fabricated composite membrane offers reasonable specific capacitances of 220 F/g at a current density of 1 A/g even after 500 cycles in 1 M KOH solution.This cost effective successful synthesis of such hybrid membrane provides new insight into development of various multifunctional applications.3.For the development of flexible hybrid carbonaceous membrane,we prepared iron oxide doped CNF and manganese oxide?Fe@CNFMn?via electrospinning and electrospray techniques.The BET analysis and quantitative pore size distribution revealed that the Fe@CNFMn possessed a tunable porous structure with surface area of 162 m2/g with an average pore volume of 0.254 cm3/g.Resultant membrane exhibited considerable electrochemical performance of 306 F/g with 81% retention even after 500 cycles in 1 M KOH solution.Furthermore,this solid state supercapacitor revealed no obvious change in specific capacitance when subjected to bending angle up to 90 o.This work paves the way for a new route to produce fibrous textile materials with high flexibility and excellent performance for supercapacitor electrodes.4.To deal with the advances technology and various types of portable electronic equipment,we report a high performance lightweight and flexible supercapacitors with superior electrochemical performance for wearable electronic device.Development of core-shell structured hybrid membrane with help of carbon black,CNFs and polyaniline?CB@CNF/PANI?via electrospinning and electrospray techniques.Moreover,specific surface area of the CB@CNF/PANI composite nanofibers was ³33 m2/g with 75.7% micro-porosity.The synthesized supercapacitors from developed hybrid membrane offers highly stable electrochemical performance with supercapacitance of 501.6 F/g at 0.5 A/g and 92% retention even after 1000 cycles.Moreover,no obvious change in SC is seen while subjecting to various bending angles up to 180 o.This simple three-step?i.e.electrospinning,carbonization and electrospray?fabrication technique paves new insights into the development of lightweight flexible supercapacitors for future energy storage applications.This thesis explains the structure regulation for fabricating novel highly flexible CNFs for efficient and high performance supercapacitor electrodes.These highly flexible and much more cost effective fabrication technique paves new insights into the development of lightweight flexible supercapacitor electrodes in future energy storage material.