Research Of The Electrochemical Performance Of Hierarchical Porous Carbon Materials In Supercapacitors

Supercapacitor is a new type of energy storage device invented under the background of modern energy crisis and increasingly environmental problems.The capacitance value of supercapacitor is much higher than ordinary capacitors,and it also has the advantages of long cycling life,high power density,high-speed charging and discharging processes.Porous carbon is the most common electrode material for supercapacitor.Herein,hierarchical porous carbon materials with high specific capacitance and cyclic stability for the electrode of supercapacitors were prepared by adjusting the activation method and pore structure.In addition,we have conducted in-depth research on the activation principle,activation process,and factors affecting the capacitance performance of materials.1.Carex meyeriana was carbonized and cleaned to prepare a hierarchical carbon material including micropore,mesopore and macropore arrays.The as-prepared carbon sample displays a high specific surface area of 724.33m²·g^-1.The electrochemical test in a three-electrode system with 6 mol·L^-1 KOH electrolyte indicate that the carbon material has ideal electric double layer capacitor performance,the specific capacitance being 182F·g^-1(0.5A·g^-1)and high rate property(116F·g^-1 remained at 20A·g^-1).The double electrode button capacitor made of this carbon electrode material has a capacitance retention rate of 98%after10,000 constant current charge/discharge tests.2.The nitrogen-doped porous carbon nanoribbons?NPCNRs?were prepared from polypyrrole?PPy?nanotubes via a thermal annealing process and KOH activated in N₂.PPy nanotubes were synthesized through a template self-degradation method using MO-FeCl₃ as template.The unique 2D nanoribbon structure of this material facilitates electrolyte diffusion and electron transport.Nitrogen adsorption test proves that the material is a hierarchical porous material mainly composed of micropores with high BET surface area(2492.57m²·g^-1).The X-ray photoelectron spectroscopy?XPS?test proves that nitrogen has many nitrogen-containing functional groups in the carbon material structure.The hierarchical porous structure and large specific area can provide lots of electrochemically active sites to significantly improved the electrochemical performance of carbon materials.As a result,the specific capacitance of NPCNRs can be reach up to 348.2F·g^-1 at 0.2A·g^-1 and excellent cycling stability(99.9%retention at 1A·g^-1).