CO_2活化温度对N-C复合碳气凝胶结构及电化学性能的影响

采用CO2活化工艺对氮掺杂碳气凝胶(N-CA)的结构进行重整,并系统研究了活化温度对活化氮掺杂碳气凝胶(N-ACA)孔结构及电化学性能的影响。利用N2吸附数据、X-光电子能谱(XPS)和元素分析对样品的结构及元素组成进行表征。结果表明,随活化温度的升高,N-ACA的比表面积逐渐增大,其含有的氮原子分数逐渐减少,吡咯氮含量明显增加。利用循环伏安(CV)、电化学阻抗谱(EIS)等测试技术评价了碳气凝胶样品在6mol·L-1 KOH电解液中的电化学性能,结果发现,合理的孔结构与较高的吡咯氮含量是影响电容器比容量的关键因素。在5mV·s-1扫描速率下测试950-N-ACA电极的比电容值高达267.4F·g-1,经1000次充放电后比电容损失值在1.5%以内。

Effect of CO2 temperature on porous textures and electrochemical performance of N-C composite carbon aerogels

Abstract:The physical structure of N-doped carbon aerogel(N-CA) is modified with CO₂ technology. The effect of activation temperature on the porous texture and the electrochemical performance of activated N-doped carbon aerogel(N-ACA) as electrode material of supercapacitors are investigated. The porous structure and elemental composition of the N-doped aerogels are tested by nitrogen adsorption at 77 K, X-ray photoelectron spectroscopy (XPS) and elemental analysis. With further increasing of the activation time,the surface area of N-ACA increases, and the concentration of nitrogen decreases continually but not the pyrrolic. The electrochemical performance of N-doped carbon aerogels is confirmed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the appropriate porous texture and the concentration of pyrrolic have crucial effect on the electrochemical performance of the electric double-layer capacitors. The specific capacitance of the 950-N-ACA electrode obtained from cyclic voltammetry measurement in 6 mol·L^-1 KOH aqueous solution at a scan rate of 5 mV·s^-1 is up to 267.4 F·g^-1 and loses about 1.5% after 1000 charge-discharge cycles.