Chagnes Alexandre, Nicolis Stamatios, Carré Bernard, Willmann Patrick, Lemordant Daniel
Laboratoire de Physico-chimie des Interfaces et des Milieux Réactionnels (EA2098) Faculté des Sciences, Université de Tours Parc de Grandmont 37200 Tours, France.
Chemphyschem. 2003 Jun 16;4(6):559-66. doi: 10.1002/cphc.200200512.
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 epsilon = 3 at the surfaces of the ions. A fair agreement between experimental and calculated activation energy has been found for systems composed of gamma-butyrolactone (BL) as solvent and lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) as salts.
提出了一种用于计算浓有机电解质中离子 - 偶极相互作用能的算法。离子 - 偶极相互作用随盐浓度的增加而增强，在计算电导率的活化能时必须予以考虑。在这种情况下，离子 - 偶极相互作用对该传输过程活化能的贡献与离子 - 离子相互作用的贡献具有相同的数量级。对于放置在扩展立方晶格顶点上的八个离子（阴离子和阳离子交替排列）组成的单元，计算了离子 - 偶极相互作用能，该晶格参数与平均离子间距离相关（伪晶格理论）。通过假设随机紧密性为0.58，将溶剂偶极随机引入单元中。使用牛顿 - 拉夫逊数值方法使单元中偶极集合的能量最小化。通过一个距离参数和离子表面介电常数ε = 3来考虑离子周围的介电场梯度。对于由γ - 丁内酯（BL）作为溶剂以及高氯酸锂（LiClO4）、四氟硼酸锂（LiBF4）、六氟磷酸锂（LiPF6）、六氟砷酸锂（LiAsF6）和双（三氟甲基磺酰）亚胺锂（LiTFSI）作为盐组成的体系，实验活化能与计算活化能之间取得了较好的一致性。
