磷酸活化制备棉杆基活性炭及其超级电容器性能研究

Preparation and supercapacitor performance of activated carbons from cotton stalks with phosphoric acid as activators

以棉杆为原材料,分别通过磷酸活化与磷酸-水蒸气混合活化法制备了具有发达孔结构的棉杆基活性炭。考察了磷酸浓度、水蒸气活化温度对活性炭产率、表面积及超级电容器电化学性能的影响。分别采用傅里叶变换红外光谱仪、氮气吸脱附测试对棉杆基活性炭的表面官能团、比表面积、孔径分布进行表征;利用两电极系统,通过恒流充放电对棉杆基活性炭作为超级电容器电极的电化学性能进行表征。结果表明:活性炭收率随着磷酸浓度的增大而降低,最高比表面积可达1718m2/g,以微孔为主;活化温度700℃,混合法得到的活性炭作为超级电容器电极材料时,首次比容量可达218F/g,循环1000次以后能保持在196F/g左右,具有很好的电化学性能。

By phosphoric acid activation and phosphoric acid-steam activation, an activated carbon with high specific surface area was developed using cotton stalks as the carbon feedstock from Xinjiang. The effects of phosphoric acid concentrations and activation temperatures on the yield and electrochemical properties of the activated carbons were investigated. The functional groups, specific surface areas and pore size distribution of the activated carbons were analyzed by FT-IR spectroscopy and nitrogen adsorption-desorption test, respectively. The electrochemical properties of the activated carbons as electrodes for supercapacitors were studied through the two-electrode system by galvanostatic charge-discharge test. The results showed that the yield decreased with the increase of concentration of phosphoric acid and activation temperatures. The activated carbons possessed the highest specific surface area of 1718m^2/g, and mainly composed of micropores activated at 900℃.The first specific capacitance of resultant activated carbon AC700 can reach 218F/g, and retained 196F/g after 1000 charge-discharge cycles. The cotton stalk based activated carbon showed good electrochemical performance.