超级电容器用活性炭电极表面氧化改性后的电化学性能

以椰壳活性炭和杏壳活性炭为原料,采用浓硝酸液相氧化改性处理后,制成以 KOH 为电解液的超级电容器的炭电极。采用低温 N_2吸附法表征了活性炭的孔结构性质,并采用循环伏安法和交流阻抗法考察了活性炭电极的电化学性能。实验表明,经浓硝酸氧化处理后,活性炭的比表面积和孔容降低,平均孔径增大。但由于氧化处理后材料赝电容的增加,椰壳活性炭和杏壳活性炭的放电容量不但没有降低.反由原来的114 F·g~(-1)和98 F·g~(-1)分别增大到166 F·g~(-1)和157 F·g~(-1)。同时,浓硝酸氧化降低了活性炭电极的表面电荷迁移电阻和时间常数。

Electrochemical performance of surface oxidized activated carbon electrodes for supercapacitor

To investigate the effect of oxidation treatment of activated carbon on electrochemical performance of supercapacitor, coconut shell derived activated carbon(CC)and apricot shell derived activated carbon(APC)were modified by concentrated nitric acid(HNO_3)oxidation and then manufactured into electrodes of supercapacitors with KOH solution as the electrolyte. Nitrogen adsorption method was adopted to characterize the pores in the original and modified activated carbons and cyclic voltammogram and AC impedance tests were used to examine the electrochemical performance.It has been found that both the surface area and pore volume of the carbons decreased and the average pore size increased after HNO3 treatment.However,the specific capacitances of CCN and APC didn't reduce with the decrease of surface area and pore volume.On the contrary,their specific capacitances increased from 114 F·g~(-1)and 95 F·g~(-1)to 166 F·g~(-1)and 157 F·g~(-1),respectively,because of the increase of their pseudocapacitance.In the meantime,both the charge transfer resistance and time constant of the two activated carbons decreased significantly after modification.