Structural Design Of Porous Carbon Materials For Supercapacitors And Its Electrochemical Performance

Porous carbon nanomaterials possess numerous unique properties,such as high specific surface area,excellent chemical stability,and high thermal stability.The presence of pores allows for a significantly increased surface area and ion channels,making porous carbon nanomaterials a potential key component in future supercapacitors.In this thesis,three commonly used methods for the preparation of porous carbon materials,namely,soft template method,hard template method and no template method,are used respectively.We explore how to control the morphology and pore structure of carbon materials,so as to realize the fine tuning of their properties.The main research works include:1)Bent mesoporous carbon nanorods（BMCR）with high aspect ratio and ordered mesopores were synthesized by a one-step superassembly method.In this experiment,resorcinol-formaldehyde（RF）resin was used as the carbon source,and micelles composed of nonionic surfactant Pluronic F127 and structure guide homotrimethylbenzene（TMB）were used as soft templates.And we investigated the effect of the amount of TMB on the structure of BMCR.The results showed that different amounts of TMB had a modulating effect on the aspect ratio of BMCRs,and the change of aspect ratio also had a significant effect on the electrochemical properties of BMCRs.And the BMCR-2 added with 0.35 m L TMB had obvious ordered mesoporous characteristics,the highest aspect ratio and the highest specific surface area(585 m²·g^-1).Electrochemical tests showed that BMCR-2 has excellent specific capacitance(214.7 F·g^-1 at 0.5 A·g^-1)and cycling stability（maintained at96.3%of initial performance after 10,000 cycles）.2)Melamine-formaldehyde（MF）polymer nanospheres were used as the hard template and nitrogen source,and resorcinol-formaldehyde（RF）resin was used as the carbon source to coat the surface of MF nanospheres to form a layer of RF shell,and continued to coat the silica shell to assist in enhancing the rigidity of the RF shell,followed by pyrolysis of MF nanospheres in a limited space at the nanoscale,leaving the RF resin shell into carbon.The nitrogen-doped hollow mesoporous carbon spheres（NMHS-2）were prepared after the removal of silica.Thanks to the hollow spherical structure,porous shell and nitrogen doping,NMHS-2 exhibits a high specific capacitance of 240.9 F·g^-1,a high energy density of 6.1Wh·kg^-1,a high rate capability and a long cycle life of 92.6%of the initial performance maintained after 10,000 cycles.3)Synthesis of hollow carbon nanospheres（PHCS）with multifaceted concave pleated structures using a template-free self-polymerization method.The synthesis approach involved utilizing terephthalaldehyde and 3-aminopropyltriethoxysilane（APTES）as carbon sources,with the incorporation of ethylorthosilicate（TEOS）as a competing reactant to control the diameter and degree of concavity of PHCS.It was found that the PHCS-3prepared at a TEOS dosage of 1 m L had a high surface area(842.1 m²·g^-1)and a multifaceted pleated hollow structure,which yielded excellent supercapacitor performance.Specifically,they possess high specific capacitance(311.6 F·g^-1 at 0.5 A·g^-1),high energy density(7.4Wh·kg^-1),and excellent cycling stability（89.6%of initial performance maintained for10,000 cycles）.