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

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.