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Ion–Dipole Interactions in Concentrated Organic Electrolytes
Author(s) -
Chagnes Alexandre,
Nicolis Stamatios,
Carré Bernard,
Willmann Patrick,
Lemordant Daniel
Publication year - 2003
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200200512
Subject(s) - lithium perchlorate , chemistry , dipole , ion , lithium (medication) , hexafluorophosphate , electrolyte , lattice energy , dielectric , conductivity , ionic conductivity , activation energy , inorganic chemistry , chemical physics , analytical chemistry (journal) , ionic liquid , materials science , crystallography , organic chemistry , crystal structure , medicine , optoelectronics , electrode , endocrinology , catalysis
An algorithm is proposed for calculating the energy of ion–dipole interactions in concentrated organic electrolytes. The ion–dipole interactions increase with increasing salt concentration and must be taken into account when the activation energy for the conductivity is calculated. In this case, the contribution of ion–dipole interactions to the activation energy for this transport process is of the same order of magnitude as the contribution of ion–ion interactions. The ion–dipole interaction energy was calculated for a cell of eight ions, alternatingly anions and cations, placed on the vertices of an expanded cubic lattice whose parameter is related to the mean interionic distance (pseudolattice theory). The solvent dipoles were introduced randomly into the cell by assuming a randomness compacity of 0.58. The energy of the dipole assembly in the cell was minimized by using a Newton–Raphson numerical method. The dielectric field gradient around ions was taken into account by a distance parameter and a dielectric constant of ε=3 at the surfaces of the ions. A fair agreement between experimental and calculated activation energy has been found for systems composed of γ‐butyrolactone (BL) as solvent and lithium perchlorate (LiClO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) as salts.