Preparation Of Mesoporous Cellulose Polymer Electrolyte Membranes And Flexible Conductive Energy Storage Composites Under [Bmim]Cl System

With the increasing attention on sustainable development and the renewable green new energy,utilization of biomass materials becomes more and more important.Cellulose is an important component of biomass materials,which has good biocompatibility,biodegradability,chemical and thermal stability characteristics.The cellulose could well dissolve with the form of macromolecular chains in the green solvent of 1-butyl-3-methylimidazolium chloride([Bmim]Cl)ionic liquid.So,cellulose at the molecular level could be modified by physically and chemically to development of a variety of regenerated cellulose-based products,which are expected in the future people's production and life will have many applications.This thesis describes a modified method of "dropping-reaction" for the preparation of highly efficient,highly pure and stable[Bmim]Cl ionic liquid.[Bmim]Cl prepared by this method can easily dissolve three different kinds of cellulose and preparation of high-performance films and fiber products.The electrochemical properties of regenerated cellulose membrane as supercapacitors separator were studied.The binder-free mesoporous cellulose polymer electrolyte-based micro-supercapacitors were first assembled based on the adhesive properties of the cellulose/[Bmim]Cl system,which showed the excellent electrochemical performance.Finally,based on the cellulose/[Bmim]Cl homogeneous system,a flexible ternary component MWCNT/cellulose-mediated PEDOT:PSS electrode film(MCPP)with excellent conductivity and electrochemical properties was prepared by the cellulose-EDOT(host-guest)supramolecular self-assembly method.The main work and results of this thesis are as follows:(1)The 1-chlorobutane was drop to N-methylimidazole and the reaction time was optimized only 10 h using the "dropping-reaction" method,and therefore obtained high-purity[Bmim]Cl.Cellulose samples from a variety of different biomass sources such as wood,catkin and linter were rapidly and completely dissolved in the[Bmim]Cl using a microwave-assisted ionothermal route.The chemical structure,degree of polymerization,crystallinity and thermal stability properties of the regenerated cellulose(RE)samples were fully characterized and analysis.(2)The transparent film can be well prepared by control of the the morphology of the regenerated cellulose.The RE-film exhibited high light transmittance of over 90%and smooth surface(Ra was less than 12 nm).The mechanical properties of three types of RE-film were improved with the increase of cellulose content.When the cellulose content was 2 wt%,the ultimate tensile stress and the Young's modulus were exceed the 200 MPa and 7 GPa.(3)The use of flexible,transparent and high mechanical properties of RE-film as the separator to assemble supercapacitors was investigated in this paper.Based on the RE-film as separator in 6 M KOH,the supercapacitor device with activated carbon as electrode exhibited a superior specific capacitance of 146 F/g and remarkable cycling stability of 98.8%retention up to 10 000 cycles.It was due to the soppy mesoporous cellulose polymer electrolyte exhibited high ionic conductivity of 0.3256 S/cm and excellent electrolyte retention of 451.25 wt%for 48 h,The supercapacitor device applying the mesoporous cellulose polymer electrolyte displayed outstanding electrochemical property such as high capacitance of 120.6 F/g and superior rate capability of 67.5%(10 A/g)and excellent cycling stability of 84.7%after 10 000 cycles and favourable lifetime stability for more than 10 days.(4)As the CLE/[Bmim]Cl system with the contact material to form a strong H-bonding interaction,intermolecular force or electrostatic interactions,it has excellent adhesive property and easily stick to the contacting substance.We had developed the simply route to assemble the binder-free mesoporous cellulose polymer electrolyte micro-supercapacitors(CMSCs)with excellent flexibility and electrochemical property.The AC-based CMSCs showed a superior areal capacitance of 153.34 mF/cm2 and volumetric capacitance of 191.66 F/cm3 and excellent cycle stability of 93.4%retention after 1000 cycles and superhigh volumetric energy density of 6.6549 mWh/cm3.Most important,the simple "green chemical" route exhibits the outstanding scalability which not only can assemble different configurations and sizes symmetric CMSCs,but also is suitable for assembly of asymmetric CMSCs.(5)A flexible strategy,ionic liquid-based cellulose-EDOT supramolecular self-assembly was put forwarded to assemble flexible and conductivity cellulose-mediated PEDOT:PSS composite film.The conductivity of the binary film material can reach 30 S/cm.When the multi-walled carbon nanotubes were introduced,the as-prepared 3D MWCNT-reinforced cellulose-mediated PEDOT:PSS films(MCPP)exhibited favorable mechanical flexibility and outstanding conductance stability up to 275 S/cm and efficient energy storage performance.The superior flexible electrodes displayed superior electrochemical activity,such as high gravimetric capacitance of 485 F/g and good cyclic stability with a capacitance retention of 95%after cycling for 2000 times.An all-solid-state laminated symmetric supercapacitor of MCPP was fabricated and exhibited specific capacitance of 380 F/g at 0.25 A/g and energy density of 13.2 Wh/kg.