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Investigation of the Ion Storage/Transfer Behavior in an Electrical Double‐Layer Capacitor by Using Ordered Microporous Carbons as Model Materials
Author(s) -
Nishihara Hirotomo,
Itoi Hiroyuki,
Kogure Taichi,
Hou PengXiang,
Touhara Hidekazu,
Okino Fujio,
Kyotani Takashi
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802406
Subject(s) - microporous material , materials science , propylene carbonate , capacitance , carbon fibers , electrolyte , chemical engineering , specific surface area , composite material , organic chemistry , electrode , chemistry , composite number , catalysis , engineering
Ordered microporous carbon : The mechanism of an electrical double‐layer capacitor containing zeolite‐templated carbons as model microporous materials was investigated in detail (see figure). Its three‐dimensionally ordered and connected micropores were found to greatly reduce ion‐transfer resistance and, therefore, exhibited a high rate performance.An ordered microporous carbon, which was prepared with zeolite as a template, was used as a model material to understand the ion storage/transfer behavior in electrical double‐layer capacitor (EDLC). Several types of such zeolite‐templated carbons (ZTCs) with different structures (framework regularity, particle size and pore diameter) were prepared and their EDLC performances were evaluated in an organic electrolyte solution (1 M Et 4 NBF 4 /propylene carbonate). Moreover, a simple method to evaluate a degree of wettability of microporous carbon with propylene carbonate was developed. It was found that the capacitance was almost proportional to the surface area and this linearity was retained even for the carbons with very high surface areas (>2000 m 2 g −1 ). It has often been pointed out that thin pore walls limit capacitance and this usually gives rise to the deviation from linearity, but such a limitation was not observed in ZTCs, despite their very thin pore walls (a single graphene, ca. 0.34 nm). The present study clearly indicates that three‐dimensionally connected and regularly arranged micropores were very effective at reducing ion‐transfer resistance. Despite relatively small pore diameter ZTCs (ca. 1.2 nm), their power density remained almost unchanged even though the particle size was increased up to several microns. However, when the pore diameter became smaller than 1.2 nm, the power density was decreased due to the difficulty of smooth ion‐transfer in such small micropores.