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

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