May 4, 2012
Aligned carbon nanotubes and non-aqueous electroytes ramp up performance of supercapacitors
Combining aligned carbon nanotubes and non-aqueous electrolytes can lead to supercapacitors with high power and energy densities, say researchers in Korea. Straight nanoconduits established by aligned carbon nanotubes enable the fast movement of ions to and from the electrode surface, and ensures high-power operation. The wide voltage window of non-aqueous electrolytes improves energy density by an order of magnitude compared with the use of aqueous electrolyte counterparts.
Reporting their results in the journal Nanotechnology, the scientists from Korea University have demonstrated such a high-performance supercapacitor. High-power performance was achieved using aligned carbon nanotubes with a straight and regular pore structure, which is significantly advantageous compared with the more conventional use of activated carbon with a tortuous and irregular pore structure. The well defined pore structure greatly improves the accessibility of ions to the surface of the electrode materials and, as a result, benefits the power characteristics of supercapacitors.
A high energy density was achieved using non-aqueous electrolytes, such as organic electrolyte or ionic liquid, which have operating voltage windows that are about three times wider than that of aqueous electrolytes. Also, opening the tip of the carbon nanotubes by a mild oxidation process led to a further increase in specific capacitance and energy density. The energy density is proportional to the capacitance and to the square of the operation voltage.
More information can be found in the journal Nanotechnology.
About the author
Byungwoo Kim is a PhD candidate under the supervision of Prof. Woong Kim based in the Department of Materials Science and Engineering at Korea University. This work was performed through a collaboration with Prof. Haegeun Chung at Konkuk University.