Fabrication Of Lignosulfonate-Based Micro-Nano Materials Via Self-Assembling And Their Electrochemical Properties

Lignin,as the second most abundant biomass on the earth after cellulose,is a three-dimensional structure polymer linked by phenylpropane units through ether bonds and carbon-carbon bonds.Lignin is the most abundant aromatic compound in nature,and it has the advantages of biodegradability and biocompatibility.Lignosulfonate is a kind of water-soluble lignin due to the introduction of sulfonate groups during chemical cooking.It is also an amphiphilic surfactant mainly used as low-value-added products such as cement water reducer and dye dispersant.Based on lignosulfonate 's structural characteristics,this study intends to prepare lignin-based micro-nano materials and tested their electrochemical properties,which provided a new way for the application of lignosulfonates.In this thesis,the amphiphilic structure property of industrial lignosulfonate was effectively utilized to prepare lignosulfonate-based micro-nanomaterials by a low-energy,green,self-assembly method.At the same time,using lignosulfonates as a synergistic template,the assembly process and regulation mechanism of fructose under hydrothermal conditions were also studied.The main results are shown as follows:1.A bottom-up self-assembly method was successfully prepared to convert lignosulfonates into graphene-like materials.This method has a wide range of raw materials,low cost,simple operation and easy morphology control.Firstly,the amphiphilic characteristics of lignosulfonate were utilized to prepare flaky lignosulfonate nanosheets with a thickness of about 18.78 nm by self-assembly due to the interaction of hydrogen bond and ?-? bond in water/acetone two-phase solvent.Then,after high temperature carbonization,the lignosulfonate-based graphene-like materials could be obtained.The thickness of the nanosheets was reduced to 1.2 nm,and the lattice spacing of the graphene-like materials was 0.36 nm,which was consistent with the characteristic parameters of graphene.In addition,the material also showed excellent cell compatibility and electrochemical properties.The ultra-thin and ultra-light lamellar nano-lignosulfonate/graphene thin film electrodes without support and without adhesives were successfully fabricated by vacuum suction and self-assembly by using flaky lignosulfonate nanosheets and graphene.The specific capacitance of nano-lignosulfonate/graphene composite film electrode was 120 mF/cm2,and the capacitance of the composite electrode was increased by 6.67 times with the addition of nano-flake lignosulfonate.2.Based on self-assembly method,rod-like nanomaterials derived from lignosulfonate were successfully prepared in ethanol/water two-phase solvents.The rod-like materials were spindle-shaped,with a middle width of two tips,a length of 1-2 um and a width of about 40.28 nm.In the process of self-assembly of two-phase solvents,the morphology of rod-like materials was related to the concentration of reactant substrate.When the initial concentration of lignosulfonate reached 5 mg/mL,the rod-like materials were dumbbell-shaped.At the same time,the assembly process and mechanism of rod-like materials were speculated.3.Yolk-Shell fructose-based microspheres with controllable morphology were successfully prepared by using lignosulfonate/P123 synergistic soft template method and fructose as carbon source through hydrothermal carbonization process.The holllow and porous Yolk-Shell fructose-based carbon microspheres after high temperature carbonization possessed superior specific surface area of 535.04 m2/g and a pore volume of 0.26 cm3/g.In addition,they also exhibited good electrochemical properties as the specific capacitance was 96 F/g,the energy density was 3.16 Wh/kg and the power density was 28.06 W/kg when the current density was 0.1 A/g.4.Fructose-based microspheres with controllable morphology were also successfully prepared by hydrothermal carbonization self-assembly using fructose as carbon source and lignosulfonate/F127 synergistic as soft template.After carbonization at high temperature,fructose-based carbon microspheres with a large number of microporous and mesoporous materials and rough surface were obtained.The results showed that the material had relatively high specific surface area of 489.90 m2/g with a pore volume of 0.26 cm3/g and an average pore size of 2.22 nm.It also exhibited good electrochemical properties,in which the specific capacitance was 95 F/g,the energy density was 3.22 Wh/kg and the power density was 28.45 W/kg when the current density was 0.1 A/g.