Preparation Of Soappindus Mukorossi Peel-based Carbon Material And Study On Its Electrochemical Performance

As an important energy storage device,supercapacitors are widely used in lifting equipment,consumer electronics,industrial automation and other fields due to their high energy density,fast charge and discharge capabilities,and long cycle life.The performance of a supercapacitor is largely determined by the electrode material as a core component.Biomass carbon materials are widely used as electrode materials because of their easy access to raw materials,rich heteroatom groups,and environmental protection,but their specific capacity is not high enough.Transition metal compounds have high specific capacitance and relatively rich resources,and are regarded as electrode materials with great development potential.However,it produces a violent response to pseudocapacitance,resulting in poor cycling stability of the capacitor.Combining biomass carbon materials and transition metal compounds to prepare new electrode materials,the performance of supercapacitors will be greatly improved.In this paper,the waste biomass material Soappindus Mukorossi Peel(SMP)is used as the carbon source,and the porous carbon material self-doped with nitrogen and oxygen is successfully prepared by the carbonization-activation two-step method.During the experiment,the pore structure and pore size distribution of the carbon materials were adjusted by changing the quality of the activator added,the activation temperature and the type of the activator.The hydrophilicity of the electrode material can be improved by doping the carbon material with heteroatoms such as B and N for surface modification.In addition,metal compounds are compounded on the basis of biomass carbon materials to increase the specific capacitance of carbon materials.The specific research methods are as follows:(1)Preparation of nitrogen and oxygen self-doped porous carbon material and its electrochemical performanceBiomass waste SMP is used as a carbon source.Through a two-step carbonization-activation method,a porous carbon material self-doped with nitrogen and oxygen is successfully prepared.The influence of the amount of different activators on the morphology and performance of carbon materials is discussed in detail in this article.The results show that when the mass ratio of alkali to carbon is 3:1,the activated carbon material has a relatively large specific surface area(1254.5 m~2/g)and a rich pore structure(a layered pore structure).The electrochemical test results show that the material has high specific capacitance(when the current density is 1 A/g,the specific capacitance value is as high as 314.5 F/g);good cycle stability(after 5000times of constant current charge and discharge,the specific capacitance Only a decrease of about 4.2%).In order to simulate the performance of this electrode material in the actual application process,it was assembled into a symmetrical supercapacitor,and its electrochemical performance was tested in a 6 M KOH electrolyte.The results showed that the material has a higher energy density.(At a current density of 100 m A/g,the energy density is 6.68 Wh/Kg)and power density(at a current density of 5 A/g,the power density can reach 3250 W/Kg);in addition,sodium sulfate electrolysis The voltage working range of the electrode material was studied in the solution,and the results showed that the working voltage of the electrode material in the sodium sulfate system(0-2 V)is wider than that in the alkaline system(0-1.5 V),and the electrochemical performance is relatively Stable(the CV curve and GCD curve are more severely deformed in alkaline electrolyte).(2)Preparation and electrochemical performance of SMP-based carbon materials at different activation temperaturesKOH and SMP toner were mixed according to the mass ratio of 3:1.After they were infiltrated with each other,they were activated at different temperatures(400℃-700℃),and the samples were successfully prepared.The structure and properties of different samples were studied.The results show that:when the activation temperature is 500℃,the sample has the most suitable pore size distribution(macropores-mesopores-micropores are related to each other)and high specific surface area(1254.5 m~2/g),and a high degree of reversibility(when current density When increasing from 0.5 A/g to 10 A/g,the shape of the GCD curve does not appear obvious distortion),good rate performance,long cycle life(5000 cycles of charge and discharge at a current density of 1 A/g,specific capacitance The retention rate is around 98.2%).(3)Preparation of boron-nitrogen co-doped porous carbon material and its electrochemical performanceSMP is used as a carbon precursor,zinc chloride is used as an activator,boric acid and urea are used as a source of boron and nitrogen,respectively.Boron-doped,nitrogen-doped and boron-nitrogen co-doped porous carbon materials were successfully prepared by one-step synthesis method.The experimental results show that,compared with the single element doping of boron and nitrogen,the co-doping of boron-nitrogen significantly improves the active sites and wettability of the carbon material,which is beneficial to the increase of the specific capacitance of the material.The material has good thermal stability at high temperatures.The composite material also has a high specific capacitance(when the current density is 0.5 A/g,the value of the specific capacitance is 145 F/g),and good reversibility(when the scan rate is increased from 5 mv/s to 100 mv/s,The CV curve has no obvious deformation),and the cycle stability is good(under the current density of 2 A/g,2000 times of constant current charge and discharge tests,the retention rate of specific capacitance is about96.4%).(4)Preparation of CoO@Co/N-SMPC Composite Material and Study on Its Electrochemical PerformanceIn this paper,the precursor of the composite material was obtained by the hydrothermal synthesis method.Then the melamine and the precursor of the composite material are uniformly mixed and then calcined at a high temperature in a nitrogen atmosphere.The porous carbon composite material CoO@Co/N-SMPC co-doped with cobalt-nitrogen with a core-shell structure with cobalt oxide as the shell metal cobalt as the core was successfully prepared.The structure and properties of composite materials are carefully studied.The results show that the CoO@Co/N-SMPC-1 carbon material has a layered pore structure,and nano particles of similar size are uniformly distributed on the surface of the carbon material,and these small particles have almost no agglomeration phenomenon,and the electrode material The specific surface area is large(1534.51 m~2/g)and the pore structure distribution is appropriate;the electrochemical behavior in the three-electrode system shows that the CV curve of this electrode material has obvious redox peaks,which indicates that the material has typical pseudocapacitance behavior,And the specific capacitance is high(under the current density of 5 A/g,the value of the specific capacitance is 491.5 A/g);the cycle stability is good(after 5000 cycles of charging and discharging,the retention rate of the specific capacitance is 92.4%).