玉米芯基氮掺杂多孔炭的制备及其电化学性能研究

Preparation and electrochemical performance study of corncob-based nitrogen-doped porous carbon

以农业废弃物玉米芯为炭前驱体、氢氧化钾为活化剂,通过氮掺杂结合预炭化和化学活化法制备了氮掺杂分级多孔炭。结果表明,三聚氰胺与预炭化生物炭的质量比为1∶1、活化温度为800℃时制备的多孔炭材料具有最大的比表面积(3639 m^(2)/g)和孔容(1.96 cm^(3)/g)。与其他氮源相比,三聚氰胺有利于炭材料中氮原子的均匀掺杂和分级孔结构的形成。该电极材料在三电极体系中0.5 A/g时获得了342 F/g的高比电容,在10 A/g下比电容仍达到303 F/g。两电极体系中,该材料在500 W/kg时能量密度为32.3 Wh/kg;该器件在10 A/g下进行10000次充放电后电容保持率为82.2%。

Nitrogen-doped hierarchical porous carbon materials are prepared through nitrogen-doping,pre-carbonization and chemical activation methods using corncob,a kind of widely sourced agricultural waste,as carbon precursor,and potassium hydroxide as activator.In addition,a nitrogen doping strategy is adopted by using melamine as main nitrogen source.Results show that the prepared porous carbon material has the highest specific surface area of 3639 m^(2)·g^(-1)and pore volume of 1.96 cm^(3)·g^(-1)when the activation temperature is 800oC and the mass ratio between melamine and pre-carbonized biochar is 1∶1.Compared with other nitrogen sources,melamine is beneficial for the uniform doping of nitrogen atoms in carbon materials and the formation of hierarchical porous structure in carbon materials.As an electrode material,this porous carbon material obtains a high specific capacitance of 342 F·g^(-1)at 0.5 A·g^(-1)in a three electrode system,and its specific capacitance still reaches 303 F·g^(-1)at 10 A·g^(-1).In a two-electrode system,the energy density of the prepared porous carbon material reaches 32.3 Wh·kg^(-1)at 500 W·kg^(-1).After having experienced 10000 charge and discharge cycles at 10 A·g^(-1),the device made from the carbon material has a capacitance retention rate of 82.2%.