Preparation Of Porous Tubular Carbon Material And Its Research On Capacitance Performance

Electrical double-layer capacitors(EDLCs)have received increasing attention due to their high power density,fast charge and discharge rate and long cycling life.EDLCs store energy physically at the electrode/electrolyte interface based on an electrochemical double-layer mechanism.Therefore,high specific surface area and short ions transport length are the basic requirement for the carbon-based electrode materials.Porous tubular carbon materials which combine the advantages of 1D nanoarchitectures and porous structures,not only can provide a high specific area,but also fast ion pathway and high electrolyte-electrode contact area,making transport of electrolyte ions faster and utilization of electrodes higher.In this paper,the N-doped carbon nanotubes(CNTs)with different microstructures have been fabricated via the pyrolysis of melamine catalyzed by FeCl3.The morphologies of N-doped CNTs were tailored by the molar ratio of melamine and Fe Cl3 and calcined temperature.The pure CNTs with bamboo-like structure are formed at 700 °C when the molar ratio of melamine and FeCl3 is 4.The BET surface and capacitance of samples increase with increasing the molar ratio of melamine and FeCl3,and the maximum BET surface and capacitance are 294 m2/g and 67 F/g,respectively.However,the low capacitance is not sufficient for the electrode material of the electric double-layer capacitors.In order to improve the capacitance performance of carbon nanotubes,we introduce pore-forming agent ZnCl2,to increase the specific surface area of CNTs.Highly porous N-doped CNTs/Fe3 C was synthesized by a facile and one-pot method.Fe3 C nanorods were in situ formed and embedded into the inner structure of CNTs.The pore structure analysis shows that N-doped CNTs/Fe3 C possesses the large specific surface area up to 1206.23 m2/g.The N-doped CNTs/Fe3 C electrode exhibits a high specific capacitance of 181 F/g at the current density of 0.1 A/g,and excellent capacitance rate and cycling stability.In order to reduce the preparation cost,the use of waste raw material bamboo chopsticks as a carbon source.The lignin in bamboo chopsticks was removed by hydrothermal method to obtain cellulose fibers and the porous carbon microtubules/flakes composite material was prepared using KOH as an activator.The as-prepared samples possess the large specific surface area up to 2337 m2/g.They exhibit the high specific capacitance of 212 F/g at a current density of 0.1 A/g,and the capacitance retention remains 96 % at a current density of 1 A/g after 1000 cycles in 6 M KOH.The results indicate that the natural resource of bamboo chopsticks could be an essential raw material for the energy storage devices.