孔结构对煤基活性炭电极材料电化学性能的影响

Effect of pore structure on the electrochemical performance of coal-based activated carbons in non-aqueous electrolyte

  • 摘要: 以太西无烟煤为前驱体,NaOH为活化剂制备电化学电容器电极材料。采用N2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。在1mol/L (C2H5)4NBF4/碳酸丙烯酯有机电解液体系中,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:以NaOH为活化剂可制备出比表面积943mol/L~2479mol/L、比电容57F/g~167F/g的活性炭电极材料。活性炭电极材料的比电容不仅取决比表面积,而且与活性炭的孔径分布有关。孔径为2nm~3nm的中孔的存在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,从而使电容器的电化学性能得到增强。

     

    Abstract: Anthracite was activated by NaOH to prepare high-performance activated carbons as electrodes for electric double-layer capacitors. The porous structure and electrochemical characteristics of the carbons were investigated by nitrogen sorption and electrochemical methods. The effect of pore structure on the electrochemical performance of the carbons in a 1mol/L (C2H5)4NBF4/propylene carbonate (PC) electrolyte was investigated. The as-prepared activated carbons exhibit large surface areas (943-2479m2/g) and high-specific capacitances (57-167F/g). The specific capacitance depends not only on the surface area, but also on the pore size distribution (PSD) of the carbon. Pores with a size of 2-3nm are crucial for the ions to penetrate inside them for the (C2H5)4NBF4/PC electrolyte. Specific capacitance is higher and impedance is lower for the sample with a wider PSD due to the fact that electrolyte ions could easily enter the pores.

     

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