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Titolo:
Molecular dynamics simulations and spectroscopic studies of amorphous tetraglyme (CH3O(CH2CH2O)(4)CH3) and tetraglyme : LiCF3SO3 structures
Autore:
Hyun, JK; Dong, HT; Rhodes, CP; Frech, R; Wheeler, RA;
Indirizzi:
Univ Oklahoma, Dept Chem & Biochem, Norman, OK 73019 USA Univ Oklahoma Norman OK USA 73019 pt Chem & Biochem, Norman, OK 73019 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 16, volume: 105, anno: 2001,
pagine: 3329 - 3337
SICI:
1520-6106(20010426)105:16<3329:MDSASS>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
POLY(ETHYLENE OXIDE)/LII MELTS; SOLID POLYMER ELECTROLYTES; PARTICLE MESH EWALD; ALKALI-METAL SALTS; IONIC ASSOCIATION; AB-INITIO; VIBRATIONAL FREQUENCIES; COMPUTER-SIMULATION; NAI/ETHER SOLUTIONS; LITHIUM-SALTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
72
Recensione:
Indirizzi per estratti:
Indirizzo: Frech, R Univ Oklahoma, Dept Chem & Biochem, 620 Parrington Oval,Room 208,Norman, OK 73019 USA Univ Oklahoma 620 Parrington Oval,Room 208 Norman OK USA 73019 SA
Citazione:
J.K. Hyun et al., "Molecular dynamics simulations and spectroscopic studies of amorphous tetraglyme (CH3O(CH2CH2O)(4)CH3) and tetraglyme : LiCF3SO3 structures", J PHYS CH B, 105(16), 2001, pp. 3329-3337

Abstract

Systems of poly(ethylene oxide) with dissolved inorganic salts are used assolid polymer electrolytes in high energy density batteries. Amorphous tetraglyme [CH3O(CH2CH2O)(4)CH3], a model for amorphous PEO, and tetraglyme:LiCF3SO3 (lithium triflate) with an ether oxygen:li(+) ratio of 10:1 were studied by molecular dynamics (MD) simulations at 300 and 400 K. Conformational and structural analyses of Li+ interactions with tetraglyme and triflate ion oxygens are consistent with decreased Li+ coordination by tetraglyme and increased ionic aggregation at the higher temperature. Dihedral angle population density distributions for tetraglyme chains show that the trans conformation is favored for C-O bonds while the more compact gauche conformation is favored for C-C bonds and is enforced by coordination of adjacent oxygens to Li+. Calculated populations of tetraglyme conformational triads indicate that the most stable conformation around Li+-tetraglyme oxygens is tgt. Mean-square radius of gyration and end-to-end distance of pure tetraglyme chains decrease with increasing temperature and upon Li+-tetraglyme oxygen complexation, but increase at 400 vs 300 1( for tetraglyme:LiCF3SO3. The calculated Li+ coordination number remains the same with increasing temperature, but triflate ions contribute more oxygens to Li+ coordination at 400 K (4.8) than at 300 K (4.6). The MD-derived populations of Li+-CF3SO3- associated species are compared with vibrational spectral data. The increase inpopulations of [Li2CF3SO3](+) and [Li3CF3SO3](2+) from both MD simulationsand IR data implies that Li+-CF3SO3- association is increased at higher temperature. Monodentate and bidentate coordination geometries of Li+ by CF3SO3- were found. The increase in monodentate coordination of Li+ by CF3SO3- at the higher temperature frees Li+ to bridge between different CF3SO3- ions.

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Documento generato il 10/12/19 alle ore 14:45:12