| The fossil energy crisis of the 21st century had forced people to find efficient and sustainable new energy sources,and supercapacitors have gradually taken off the research boom due to their advantages such as faster charge discharge rate,excellent long cycle stability,wider operating temperature.Electrode materials are important factors in determining the performance of supercapacitors,and among numerous electrode materials,porous carbon micro/nanospheres(PCMNSs)combining the advantages of carbon materials and spherical colloids with tunable physicochemical properties,such as regular and uniform morphology size,controllable porosity,adjustable shell thickness and internal cavity,lower density,higher specific surface area and high monodispersity,etc.The synthesis of PCMNSs was mainly soft-templating method by using surfactant as a soft templating agent,which can precisely adjust the size of porous carbon spheres as well as the pore structure.By the use of surfactants,porous carbon spheres with various morphologies were obtained.The particle sizes ranged from nano to micron,and the pore sizes ranged from micropores(<2 nm),mesopores(2-50 nm)to macropores(>50 nm).Among the numerous research achievements in the synthesis of structurally controllable carbon nanomaterials by soft-template method,the kinds of carbon sources had received great attention and been studied more extensively and comprehensively.However,the structure of surfactants directly determines the microstate of micelles or vesicles in the soft templating method and had a direct effect on the structure of carbon materials.This paper mainly uses three kinds of surfactants with different structures as structure directing agents,so that the microtopography and dimensional structure of PCMNSs were precisely regulated and the controllable preparation of electrode materials for high-performance supercapacitors.The main research content of this paper are as follows:1.In the second chapter,a series of PCMNSs with high content of nitrogen and oxygen heteroatoms were first prepared by a soft templating self-doping method by using the cationic surfactant didecyldimethylammonium bromide as a soft templating agent.The prepared PCMNSs all showed uniform morphology,controllable size,higher specific surface area,larger pore volume and higher proportion of heteroatom doping.By using the unique two long hydrophobic chain structures of the double stranded cationic surfactant didecyldimethylammonium bromide,a unique three-dimensional structured soft template was constructed by adjusting the amount of surfactant and the ratio of solvent.which successfully achieved the fabrication of a three-dimensional porous carbon framework with the interconnected structure of porosity between single carbon spheres and the interior of the shell layer.Meanwhile,the three-dimensional structured carbon framework was activated with the pore former KOH,which greatly improved the porosity of three-dimensional porous carbon framework with interconnected pore structures inside the shell layer and provided more active sites for the improvement of electrochemical performance.The results showed that the three-dimensional porous carbon frameworks A-PCMNSs-0.6-35 had excellent electrochemical specific capacity(the specific capacity at 0.2 A g-1 was 256.0 F g-1),.the larger the capacitance retention rate(the specific capacity was still 170 F g-1 at ultra-high current density 100 A g-1)and excellent cyclic stability(the capacitance retention rate was 93%after 5000 cycles at 10 A g-1 current density).2.The length of the hydrophobic chain of the surfactant has a more significant effect on the structure of the soft templates,and structural control over their ordered assemblies can be achieved by varying the hydrophobic chain length of the surfactant.The third chapter of this paper mainly explored the effect of surfactants with one hydrophilic group and two longer hydrophobic chain configurations as soft templating agents on the synthesis of PCMNSs.By using didodecyldimethylammonium bromide as a soft templating agent,longer hydrophobic chain length reduced the membrane strength of surfactant micelles and formed a unique structured soft template,which successfully prepared carbon micro nanomaterials with open bowl structure.The mesopore dominated,microporous and macroporous synergistically acting hierarchical pore structured PCMNSs endow the material with efficient electrochemical energy storage performance.The results showed that the open bowl structured carbon spheres exhibited excellent EDLCs performance,excellent electrochemical specific capacitance(206.4 F g-1 at 0.2 A g-1),larger capacitance retention(128.9 F g-1 at 50 A g-1),and excellent cycling stability(93%capacitance retention after 5000 cycles at 10 A g-1 current density).3.Cationic Gemini surfactants,a special class of surfactants consisting of two hydrophilic groups and two hydrophobic chains,are more prone to interfacial polymerization due to their molecules containing two hydrophilic groups and lower critical micellar concentration than the corresponding common surfactants.The length of the flexible linker group in the middle of the hydrophilic headgroup can effectively regulate the structure of surfactant micelles.This chapter maintained the same hydrophobic chain length as the third chapter surfactants,and the length of the two hydrophilic based intermediate linkers of the Gemini surfactants were changed.Using Gemini surfactants 12-2-12,12-5-12 and 12-8-12 as soft templates respectively,the unique morphologies of honeycomb like hemispheres and surface dented carbon spheres were synthesized and tested for their electrochemical properties.The surface dented carbon spheres reached a specific capacity of 189.2 F g-1 at a current density of 0.2 A g-1.Compared with 1 A g-1,the specific capacity retention was 75.9%(132.8 F g-1)at a higher current density of 20 A g-1.Meanwhile,the unique morphological structure and abundant hierarchical pore structure have a promising application in the field of adsorption and medical support. |
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