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Electric double-layer capacitance of carbon nanocages
Makoto Tadokoro1, Satoru Tsumeda, Nobuhide Tsuhara
1Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan.
Journal of Nanoscience and Nanotechnology
|May 16, 2009
Summary
Carbon nanocage (CNC) materials offer high surface area for electrochemical applications. However, their large pore sizes limit volumetric capacitance in electric double-layer capacitors (EDLCs).
Area of Science:
- Materials Science
- Electrochemistry
- Nanotechnology
Background:
- Carbon nanocage (CNC) materials possess highly ordered, uniform pores.
- Characterization reveals pore opening sizes around 5.6 nm via TEM.
- Nitrogen adsorption isotherms classify CNCs as Type IV, indicating mesoporosity.
Purpose of the Study:
- To evaluate the capacitive performance of carbon nanocage materials.
- To compare the electrochemical properties of CNCs with activated carbon (AC-A).
- To understand the relationship between pore structure and capacitance in CNCs.
Main Methods:
- Transmission electron microscopy (TEM) for pore size analysis.
- Nitrogen adsorption-desorption isotherms (BET, BJH) for surface area and pore volume.
- Cyclic voltammetry (CV) for electrochemical capacitance measurements.
- Density and specific surface area measurements of CNC and AC-A films.
Main Results:
- CNCs exhibit high BET surface area (1515 m²/g) and pore volume (2.0 cm³/g).
- Gravimetric capacitance of CNC electrodes (ca. 200 F/g) is comparable to AC-A.
- Volumetric capacitance of CNC electrodes (ca. 50 F/cm³) is half that of AC-A.
Conclusions:
- While CNCs offer excellent gravimetric capacitance, their larger pore sizes reduce volumetric performance.
- The pore structure of CNCs, with large interfaces, is less favorable for electric double-layer capacitors (EDLCs) compared to AC-A.
- Optimization of pore size distribution in CNCs may enhance their suitability for EDLC applications.
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