Surface Roughness: A Crucial Factor To Robust Electric Double Layer Capacitors.

ABSTRACT

Electric double layer capacitors (EDLCs) usually show high rate performance and long cycling spans but inferior specific capacitance, which are mainly created by restriction of the charge storage mechanism. To improve the capacitive performance, traditional methods include enlarging surface area, optimizing porous structures, and readjusting functional groups through heteroatom doping to electrode materials. Besides that, another promising approach is suggested, which is to enhance surface roughness of the electrode materials for ion storage and transport. To prove this view, two porous carbon materials were fabricated by activation-calcination methods, which allowed the materials to have identical surface area, porous structures, and surface composition but the surface roughness. Further electrochemical measurements exhibited that the optimal sample with higher roughness has remarkable specific capacitance (up to 562 F g-1), and the increment rate is more than 50% when compared with contrast sample (367 F g-1). Therefore, optimization of the surface roughness of electrode materials is another efficient route to make robust EDLCs.