Molecular relaxation dynamics of LiClO[sub 4] in acyclic polyether solvents

Journal Article · Thu Apr 08 00:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100116a027· OSTI ID:6307033

Firman, P; Xu, M; Petrucci, S ^[1]; Eyring, E M ^[2]

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1. Polytechnic Univ., Farmingdale, NY (United States)
2. Univ. of Utah, Salt Lake City (United States)

Ultrasonic relaxation spectra are reported for LiClO[sub 4] dissolved in acyclic polyethers of increasing chain length including 1,2-dimethoxyethane (1,2-DME), CH[sub 3](OCH[sub 2]CH[sub 2])[sub n] OCH[sub 3] with n = 1; diglyme with n = 2; and tetraglyme with n = 4. Spectra were measured at 25[degrees]C at various concentrations in the frequency range approximately 1 to approximately 500 MHz. The data are analyzed in terms of the dimerization equilibrium 2LiClO[sub 4] [r reversible] (LiClO[sub 4])[sub 2], determining rate constants, equilibrium constants of dimerization, K[sub d], and isoentropic volume changes for the process, [delta]V[sub 8]. Infrared spectra for the v[sub 4] mode of ClO[sub 4][sup [minus]] at approximately 623 cm[sup [minus]1] reveal a satellite band at wavenumbers ranging from 633 to 638 cm[sup [minus]1] that is attributed to contact ion pairs. Microwave dielectric relaxation spectra of LiClO[sub 4] in the above polyethers reveal a relaxation process involving the solute (that is absent in the pure solvent) which is attributed to the rotational relaxation of LiClO[sub 4] ion pairs. The relaxation process shifts in frequency from around 2 GHz for LiClO[sub 4] in 1,2-DME to 0.21 GHz for LiClO[sub 4] in tetraglyme at 25[degrees]C. This behavior correlates well with the change in the viscosity of the solvents which has been determined separately. The apparent dipole diameter is about a[sub o] = 4 [times] 10[sup [minus]8] cm. Comparable values have been calculated from the Boettcher function determining the apparent dipole moment of the ion pairs in solution. The molar refraction of lithium perchlorate, R[sub LiClO[sub 4]], has been calculated from measured refractive indices and densities of solutions of LiClO[sub 4] in polyethers at various electrolyte concentrations. 24 refs., 10 figs., 5 tabs.

• OSTI ID: 6307033
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 97:14; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LITHIUM PERCHLORATES
DIMERIZATION
SPECTROSCOPY
ELECTRIC BATTERIES
EXPERIMENTAL DATA
MICROWAVE RADIATION
ORGANIC POLYMERS
RELAXATION
SOLVENTS
ULTRASONIC WAVES
VISCOSITY
ALKALI METAL COMPOUNDS
CHEMICAL REACTIONS
CHLORINE COMPOUNDS
DATA
ELECTROCHEMICAL CELLS
ELECTROMAGNETIC RADIATION
HALOGEN COMPOUNDS
INFORMATION
LITHIUM COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PERCHLORATES
POLYMERIZATION
POLYMERS
RADIATIONS
SOUND WAVES
250903* - Energy Storage- Batteries- Materials
Components
& Auxiliaries
400102 - Chemical & Spectral Procedures
400201 - Chemical & Physicochemical Properties