氮掺杂多孔碳的制备及其电容性能研究
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摘要
氮掺杂多孔碳(NPC)电极材料具有特殊的多孔结构导致其比表面积高、化学稳定性好同时电容性能良好,然而导电性差、能量密度低等因素也限制了其实际应用。本课题组以天然产物为碳源,经高温热解产生碳化残渣,将这些残渣经筛分、与氢氧化钾和三聚氰胺一起混合、研磨、然后再经过高温焙烧、洗涤、烘干后得到NPC样品。该样品外观为黑色粉末,在扫描电镜下观察其形貌呈现多孔状,平均孔径为290 nm,氮元素含量达到6.45 wt%。将NPC与乙炔黑、聚偏氟乙烯按8:1:1的质量比制成电极压片,可组装成对称型超级电容器。在两电极体系下,以1 MLiClO_4/DMC为电解液,通过恒电流充放电(GCD)和循环伏安(CV)测试表明:电流密度为0.5 A/g时,组装的超级电容器的比电容达到112 F/g,而且当功率密度为250 W/kg时,能量密度可达到15.5 Wh/kg。经1000次循环充放电后,其比电容仍然保持95.2%,库仑效率基本稳定在99%,从而说明NPC具有优良的电容性能和循环稳定性。
The electrode material comprised of nitrogen-doped porous carbon(NPC) owns many advantages such as a high specific surface area,agood chemical stability and an excellent capacitive performance.However,its practical applications have been restricted to a certain extent owing to the poor electrical conductivity,low energy density and etc.Here we report a NPC material synthesized by using a kind of natural product as carbon resource,which was carbonized and then sieved into fine carbide powder.After mixing the fine carbide powder with KOH and melamine,grinding and then calcination at a high temperature,the obtained black powder sample presents a porous morphology with an average pore size of 290 nm under a SEM observation,besides,the nitrogen doping content reaches 6.45 wt%.Electrodes were fabricated by mixing the NPC,acetylene black and PTFE binder in a mass ratio of 8:1:1,and thus a symmetric two-electrode supercapacitor device was assembled.The capacitance performance of the device was characterized by galvanostatic charge-discharge(GCD) and cyclic voltammetry(CV) tests in a two-electrode system while 1 M Li Cl O4/DMC used as an electrolyte.The supercapacitor shows a specific capacitance of 112 F/g at the current density of 0.5 A/g and an energy density of 15.5 Wh/kg at the power density of 250 W/kg.The capacitance retention of 95.2% as well as a high coulombic efficiency of 99% is achieved after 1000 charge-discharge cycles,which indicates the as-synthesized NPC has both an excellent capacitive property and a superior cycle stability.
引文
[1]L.Qie,W.-M.Chen,Z.-H.Wang,Q.-G.Shao,X.Li,L.-X.Yuan,X.-L.Hu,W.-X.Zhang and Y.-H.Huang,Adv.Mater.,2012,24,2047-2050.

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