Preparation And Electrochemical Properties Of Pine Based Woodceramics

As the raw material of woodceramics,biomass materials have their own unique features,such as natural pore structure,adjustable physical and chemical properties,environmental friendliness and low price.They play a great role in developing high-performance and low-cost carbon materials to promote the development of supercapacitors.This article mainly uses waste pine as raw materials.Aiming at the shortcomings of low specific capacitance and energy density of woodceramics,this article dope transition metal oxides to date pseudocapacitors,so that the two have a synergistic effect.On this basis,a composite material with high specific capacitance,good cycle stability,and a composite material with high specific capacitance,good cycle stability,and superior power density and energy density is obtained.The experiment analyzed the influence of different doping methods on the structure and performance of woodceramics materials through electrochemical tests and corresponding characterization tests.And comprehensive analysis of electrochemical performance,optimization of activation and doping conditions,finally summary of the best preparation plan,which provide a new way for the rational reasonable of green recycling sustainable biomass materials to prepare woodceramics materials.It mainly includes the following research contents:(1)Using pine wood as raw material,crushing,sieving,mixing it with phenolic resin,using a two-step method of high-temperature carbonization and hydrothermal activation to prepare massive block pine-based woodceramics with good electrical conductivity and large specific surface area.In this process,the effects of different material ratios,activation time and activation temperature on the electrochemical properties of woodceramics are mainly studied.Finally,it was found that the specific surface area(1671.997 m2·g-1)of the woodceramics prepared by hydrothermal activation for 6 h at 180℃ with a material ratio of 3:7 was relatively high.Using it as an electrode material in a 6 mol·L-1 KOH electrolyte,the maximum-specific capacitance is 118.5 F·g-1(current density is 0.1 A·g-1),and the current density increases to 2.0 A·g-1,the capacitance retention rate is 71%.After 2000 cycles of charge and discharge,the capacitance retention rate can still reach 79.3%,indicating good cycle stability.(2)Using pine-based woodceramics as the matrix,a one-step hydrothermal activation method was used to prepare a massive pine-based woodceramics/MnOx composite electrode with a three-dimensional network structure.By changing the quality of KMnO4 to explore the best doping ratio of the composite electrode,the doping of MnOx provides more active sites for the electrode material,which makes the composite material has excellent electrochemical performance.When the current density of 0.1 A·g-1,the maximum-specific capacitance obtained is 293.7 F·g-1.Which are 3.5 times that of the sample without MnOx.After 5000 cycles,it still has excellent cycle stability,and the capacitance retention rate can reach 81.9%.Additionally,in a two-electrode system,it can exhibit good energy density(24.65 Wh·kg-1)and power density(125 W·kg-1).(3)Using 0.1 mol·L-1 MnSO4 solution as the deposition solution,under the condition of pH=5-6,the bulk woodceramics/MnO2 composite electrode with MnO2 membrane structure on the surface on the surface was obtained by constant current electrodeposition method.The excellent electrical conductivity of woodceramics matrix can make up for the shortcomings of poor conductivity of MnO2,thereby increasing the usage rate of MnO2 in the charge and discharge process;finally,the introduction of MnO2 with high theoretical specific capacitancecan improve the overall composite capacitance performance of electrodes.In the three-electrode system,the composite electrode can obtain a maximum-specific capacitance of 541.2 F·g-1(0.1 A·g-1).After 5000 cycles,it still has excellent cycle stability(capacitance retention rate is 85.7%).In a symmetrical supercapacitor composed of woodceramics/MnO2 composite electrodes,when the power density is 100 W·kg-1,the energy density can reach 82.32 Wh·kg-1.By lighting the LED bulb,it illustrates the woodceramics/MnO2 composite electrode prepared by the constant current electrodeposition has practical applications value.