Preparation And Electrochemical Properties Of Nitrogen-doped Hollow Carbon Spheres And Multicomponent Co-doped Carbon Microspheres

Based on the research of carbon materials with spherical morphology,this paper designs and prepares a kind of carbon layer thickness controllable and template recyclable around doping,pore expansion,morphology control and increasing the degree of graphitization.The nitrogen-doped hollow carbon spheres?NHCSs?and a multi-element co-doped porous carbon microspheres?PCMSs?_materials,and by changing the experimental conditions and parameters,studied the material morphology,pore structure,doping content The relationship between the degree of graphitization and their electrochemical performance.The main research contents and results are as follows:1)Using Cu₂O microspheres as a hard templating agent,through the in-situ polymerization of 3-aminophenol formaldehyde resin,followed by carbonization and template etching,N-doped hollow carbon spheres?NHCSs?with a certain degree of graphitization were synthesized.The thickness of the carbon layer of the material can be well controlled by adjusting the ratio of the precursor to the hard templating agent.The prepared NHCS has a hollow spherical morphology,controlled shell thickness,unique porosity,and high nitrogen doping characteristics.Electrochemical tests showed that the sample with the thinnest carbon layer thickness?25 nm?obtained by carbonization at1000? exhibited the best electrochemical performance?specific capacitance of 263.6 F/g at a current density of 0.5 A/g?.,The corresponding volumetric capacitance is 191.3 F/cm3),excellent rate performance and excellent cycle stability?at a current density of 5 A g-1,after1000 cycles of charge and discharge,the retention rate of the capacitor is reached 90.2%?.In addition,after the etching of the template,the remaining reaction solution can also be prepared by filtration and crystallization of CuCl₂,and CuCl₂ can further prepare new Cu₂O microspheres,so as to achieve the purpose of repeated recycling of the template agent.2)The prepared NHCSs were activated by KOH,which resulted in a rich pore structure of the material,which further increased the specific surface area and pore volume of the material,thereby greatly improving the electrochemical performance of the NHCS.When the current density is 0.5 A g-1,the specific capacities of activated S1-700-K,S2-850-K and S3-1000-K are 261.7,283.6 and 327.4 F/g,respectively;at 5 A/g.Under the current density of g,the specific capacitance retention rate of these three samples reached 90.42%,90.48%and 90.60%,respectively,after performing continuous charge and discharge for 1000 cycles,showing excellent cycle stability performance of the material.3)Using glucose as a carbon precursor and ammonium fluoroborate as a dopant,a micron-scale porous carbon sphere material was successfully prepared by adopting a hydrothermal-carbonization method.By controlling the amount of dopants and the different carbonization temperatures,we found that the PCMSs-3-900,a sample with the highest dopant concentration and a carbonization temperature of 900?,had the highest specific capacitance at 0.5 A/g.At the current density,the specific capacitance reached 257.6 F/g.After further analysis,it was shown that the introduction of heteroatoms?B,F,N?into the carbon material increased the tantalum capacity of the material,and was also catalyzed by Fe3+.The increase of the carbonization temperature favors the graphitization of the carbon material.In addition,by adjusting the amount of surfactant PVP,its influence on the morphology of the material was explored,and it was found that the presence or absence of PVP did not significantly affect the formation of carbon spheres,but a large number of PVP added to make the morphology of the material serious The destruction.Therefore,this multi-co-doped PCMSs material is expected to become a new hotspot in the application of supercapacitors,and has a very large research and application prospects in the energy field.