低温预活化制备桂七芒果枝基活性炭及其电容性能分析

Preparation of Guiqi mango branch-based activated carbon by pre-activation at low temperature and analysis of capacitance performance

以广西广泛种植的桂七芒果废弃枝条为原料进行了活性炭的制备。活性炭的制备采用化学活化法,氢氧化钾为活化剂,在传统的炭化、活化工艺基础上增加了低温预活化处理步骤,并用扫描电镜、氮气吸附和电化学工作站对活性炭的表面形貌、比表面积、孔隙分布和电容性能进行表征。结果表明:增加低温预活化步骤的活性炭比表面积达到1546 m^(2)/g,孔容达到1.20 cm^(3)/g,平均孔径为3.1 nm,相比于传统工艺制备的活性炭的比表面积1065 m^(2)/g,孔容0.62 cm^(3)/g,平均孔径2.3 nm,相应的增加了45.2%,93.5%,34.8%;采用1 mol/L Na_(2)SO_(4)为电解液的三电极体系中,在2 mV/s的扫描速率下增加预活化工艺循环伏安法比电容达到76.5 F/g,比传统工艺材料比电容增加了42.5%,并且在2 A/g的电流密度下经过3000次的恒流充放电,电容保持率为98%以上。总体上低温预活化工艺可有效提高活性炭的物化性质,并在电容能力上有较好表现,也说明桂七芒果树枝也是良好的活性炭原料。

Activated carbon was prepared from the waste branches of Guiqi mango,which was widely planted in Guangxi.The activated carbon was prepared by chemical activation method with potassium hydroxide as activator.The low temperature pre-activation process was added to the traditional carbonization and activation process.The surface morphology,specific surface area,pore distribution and capacitance of the activated carbon were characterized by scanning electron microscope,nitrogen adsorption and electrochemical workstation.The results showed that the specific surface area,pore volume and average pore size of the activated carbon are 1546 m^(2)/g,1.20 cm^(3)/g and 3.1 nm,respectively.Compared with the activated carbon prepared by traditional process,the specific surface area,pore volume and average pore size of the activated carbon increased by 45.2%,93.5%and 34.8%,respectively;In the three electrode system with 1 mol/L Na_(2)SO_(4) as electrolyte,the specific capacitance of cyclic voltammetry is 76.5 F/g at the scanning rate of 2,which is 42.5%higher than that of traditional process materials.After 3000 times of constant current charge and discharge at the current density of 2 mV/s,the capacitance retention is more than 98%.In general,low temperature pre-activation technology can effectively improve the physicochemical properties of activated carbon,and has excellent performance in capacitance,which also shows that Guiqi mango branch is also a good raw material for activated carbon.