孔结构对煤基活性炭电化学性能的影响

以煤为前驱体,KOH为活化剂制备系列煤基活性炭电极材料.采用N_2吸附法及电化学测试对活性炭的孔结构和电化学性能进行了表征,研究了孔结构对活性炭电极材料的电化学性能的影响.结果表明,采用化学活化法可制备出比表面积1 048～3 581 m~2/g、中孔率7%～91%的活性炭电极材料.在3 mol/L KOH无机电解液体系及1 mol/L(C_2H_5)_4NBF_4/碳酸丙烯酯(PC)有机电解液体系中,活性炭电极材料的比电容分别达到322 F/g,190 F/g.2～3 nm的中孔对电解质离子在电极材料中的扩散有着重要作用,可以有效降低电解液的扩散阻力,提高电极材料比表面积的利用率,从而增强电容器的电化学性能.

Influence of Pore Structure of Coal-based Activated Carbons on Electric Double Layer Capacitance

The anthracite activated by KOH was used to prepare high-performance activated carbons as electrodes for electrochemical double-layer capacitors (EDLCs). Porous structure and electrochemical characteristics of the carbons were investigated by nitrogen sorption and electrochemical methods, respectively. The effect of pore structure on the electrochemical per-formance of the as-prepared carbons was studied. The results show that the carbons activated by KOH exhibit large surface areas (1 048-3 581 m~2/g), various ratio of mesopore volume (7%-91%), and high capacitance in 3 mol/L KOH electrolyte (332 F/g) and 1 mol/L (C_2H_5)_4 NBF_4/propylene carbonate (PC) electrolyte (190 F/g). The electrochemical perform-ance of the carbons was enhanced by the presence of the pores of 2-3 nm, which ensured a low impedance and a sufficient utilization of the exposed surface for charge storage, due to electro-lyte ions could easily penetrate the pores and access the porosity.