Abstract:

Activated carbons for supercapacitor electrode material were prepared by using coal-based needle coke as raw material and KOH as activator. The electrochemical properties of activated carbons were tested in a three-electrode electrochemical system with 3 mol/L KOH as electrolyte. The effect of the amount of activator on the electrochemical properties of the carbon electrode material was investigated. The results show that the electrochemical properties of the activated carbon increases gradually with the increase of the KOH/coke mass ratio during the activation process. When the carbon and alkali ratio is 1∶3, the specific surface area of the activated carbon reaches 2572.7 m²/g. The specific capacitance of the activated carbon is 316 F/g at a current density of 1 A/g. The capacitance retention rate is 95.7% after 5000 cycles with the coulombic efficiency remaining at 97.0%. The electrochemical performance of the activated carbon was further investigated in a two-electrode system. In the electrolyte of 1 mol/L Na₂SO₄, and at a widened voltage window of 1.8 V, the cyclic voltammetry curve is also in good rectangular shape, leading to an energy density of 20.8 W·h/kg and a power density of 230 W/kg.

Key words: coal-based needle coke, supercapacitor, electrochemistry, energy density, activated carbon, activation

摘要：

以煤系针状焦生焦为原料，KOH为活化剂，制备了用于超级电容器电极材料的活性炭。以3 mol/L KOH为电解液，用三电极电化学系统测试了活性炭的电化学性质；考察了活化剂用量对活性炭电化学性质的影响。研究结果表明：活化过程中，随着碱含量的增加，活性炭的电化学性能逐渐提高。当碳碱比为1∶3时，活性炭的比表面积达到2572.7 m²/g；电流密度为1 A/g时，其质量比电容达到316 F/g。循环5000圈之后，比电容保持在95.7%，库仑效率保持在97.0%。采用两电极系统，进一步考察了活性炭的电化学性能，以1 mol/L Na₂SO₄为电解液，电压窗口拓宽至1.8 V，循环伏安曲线同样展现出良好的矩形，能量密度和功率密度分别为20.8 W·h/kg和230 W/kg。

关键词: 煤系针状焦, 超级电容器, 电化学, 能量密度, 活性炭, 活化