| In this paper,the latest research progress of supercapacitors was reviewed,especially focused on the preparation of carbon materials for supercapacitors and the development status of structural control technology.The relationship between the pore structure of carbon materials and the performance of supercapacitors is systematically studied.This is a fundamental but very important scientific problem.However,there is only qualitative analysis or explanation for the problem,no experimental verification,which is attributed to the complexity of the system and the uncon troll ability of carbon structure.Therefore,a new method for preparing porous carbon materials with controllable pore size by direct carbonization of interpenetrating polymers network is proposed.This work is based on controllable polymer structure-controllable carbon material structure-high performance carbon electrode material of supercapacitor as the main line.The interpenetrating polymer is used as a precursor to prepare a porous carbon material with controlled pore size,which realizes the controlled macropores,mesopores and micropores.And the relevant reaction conditions are controlled to control the synthesis of polymer.Furthermore,the capacitance performance is further tested to discuss the intrinsic relationship between porous carbon structure and electrochemical energy storage performance.The main contents are presented as follows:(1)A simple carbonization method is proposed for the synthesis of controllable pore size and specific surface area for hierarchical porous carbons.That is,the hierarchical porous carbons is from the direct carbonization of interpenetrating polymer networks(IPNs)which is comprised of phenol-formaldehyde resin(PF)and sodium polyacrylate(PAAS).The preparation of hierarchical porous carbon with controllable pore size and specific surface area,connected pore structure and excellent electrochemical performance is from the carbonization of different mass ratios of interpenetrating polymers.Compared with HPC-0.5,HPC-1.5 and HPC-2,HPC-1 carbon material has the largest specific surface area(1764 m2 g-1)and pore volume(1.111 cm3 g-1).When used as the electrode material of the supercapacitor,HPC-1 has the largest specific capacitance value of 201 F g'1 at the current density of 0.5 A g-1 in 6 M K,H electrolyte and excellent cyclability of approximately 100%of capacitance retention after 10000 cycles.Furthermore,the as-assembled symmetric supercapacitor exhibits a specific capacitance of 77.8 F g"1 at the current density of 0.5 A g-1 in 1 M Na2SO4 electrolyte.(2)Interpenetrating polymers networks PF/PAAS-IPNs were used as precursors to systematically study the effect of nitric acid activation on the structure and electrochemical properties of carbon materials.Due to the successful introduction of oxygen and nitrogen functional groups such as-NO2 and-OH,the surface wettability of activated carbon surface is enhanced,which makes that electrolyte ions fully contact with electrode materials and increases surface utilization of carbon materials.Moreover,after nitric acid activation treatment,the capacitance performance of carbon material is significantly improved,which is ascribed to these functional groups that can contribute a large part of the pseudocapacitance.In addition,the activation of nitric acid increases the specific surface area and forms a large number of microporous and ultramicroporous structures,thus improving the stability of the capacitor.High-performance nitrogen-doped hierarchical porous carbon AHPC8-80-5 was successfully prepared by changing the concentration,time and temperature of nitric acid activation.The as-obtained carbon material delivers a specific surface area of up to 2068 m2 g-1 and a pore volume of 1.510 cm3 g-1 and a suitable nitrogen content of 0.25%.AHPC8-80-5 has a high specific capacitance(305 F g-1),good rate performance(67%capacity retention)and good cycle stability(95%capacity retention). |
PDF Full Text Request