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Relationship Between Structural Properties and Electrochemical Characteristics of Monolithic Carbon Xerogel‐Based Electrochemical Double‐Layer Electrodes in Aqueous and Organic Electrolytes
Author(s) -
Zeller Mario,
Lorrmann Volker,
Reichenauer Gudrun,
Wiener Matthias,
Pflaum Jens
Publication year - 2012
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201100513
Subject(s) - materials science , microporous material , electrolyte , electrochemistry , chemical engineering , aqueous solution , pyrolysis , carbon fibers , electrode , specific surface area , macropore , layer (electronics) , capacitance , cyclic voltammetry , inorganic chemistry , nanotechnology , composite material , catalysis , organic chemistry , chemistry , mesoporous material , composite number , engineering
The impact of the micropore width, external surface area, and meso‐/macropore size on the charging performance of electrochemical double‐layer capacitor (EDLC) electrodes is systematically investigated. Nonactivated carbon xerogels are used as model electrodes in aqueous and organic electrolytes. Monolithic porous model carbons with different structural parameters are prepared using a resorcinol‐formaldehyde‐based sol–gel process and subsequent pyrolysis of the organic precursors. Electrochemical properties are characterized by utilizing them as EDLC half‐cells operated in aqueous and organic electrolytes, respectively. Experimental data derived for organic electrolytes reveals that the respective ions cannot enter the micropores within the skeleton of the meso‐ and macroporous carbons. Therefore the total capacitance is limited by the external surface formed by the interface between the meso‐/macropores and the microporous carbon particles forming the xerogel skeleton. In contrast, for aqueous electrolytes the total capacitance solely depends on the total surface area, including interfaces at the micropore scale. For both types of electrolytes the charging rate of the electrodes is systematically enhanced when increasing the diameter of the carbon xerogel particles from 10 to 75 nm and the meso‐/macropore size from 10 to 121 nm.