A carbon-13 and lithium-6 nuclear magnetic resonance study of lithium perchlorate/poly (ethylene oxide) electrolytes

O’Gara, John F.; Nazri, G.A.; MacArthur, Donald M.

doi:10.1016/0167-2738(91)90185-e

Cited by 37 publications

(22 citation statements)

References 14 publications

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“…With regard to ion pair and cluster identification in Li-containing polymer electrolytes, O'Gara and coworkers have recently utilized CPMAS 6 Li NMR, which appears to be a promising alternative to 7 Li due to its greater chemical shift resolution. [26] In studies of PEO:LiC10 4 , three distinct 6 Li peaks were assigned to different kinds of dissociated Li÷ ions while tw, additional peaks assigned to isolated ion pairs and larger clusters were distinguished on the basis of their 'H cross polarization responses. [26] The question of what mechanism drives ion association and, in some cases, salt precipitation in polymer electrolytes remains controversial.…”

Section: Review Of Experimental Resultsmentioning

confidence: 99%

“…[26] In studies of PEO:LiC10 4 , three distinct 6 Li peaks were assigned to different kinds of dissociated Li÷ ions while tw, additional peaks assigned to isolated ion pairs and larger clusters were distinguished on the basis of their 'H cross polarization responses. [26] The question of what mechanism drives ion association and, in some cases, salt precipitation in polymer electrolytes remains controversial. Ratner and coworkers discuss an entropic mechanism which is related to volume differences between the polymer-salt complex and the polymer plus precipitated salt.J27] On the other hand, dielectric measurements of PPO coupled with salt precipitation trends among Na salts with different anions suggested that electrostatic considerations were important.…”

Section: Review Of Experimental Resultsmentioning

confidence: 99%

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NMR studies of ion mobility and association in polyether‐based polymer electrolytes

Greenbaum

1993

Polymers for Advanced Techs

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The results of several investigations of polyether‐based polymer electrolytes by nuclear magnetic resonance (NMR) spectroscopy conducted in the author's laboratory and by other groups are reviewed. For both 7Li and 23Na NMR, the onset of motional line‐narrowing occurs at about the glass transition temperature, illustrating the importance of polymer segmental motion to ion transport. Examples of the ability of NMR to probe cationanion interactions are discussed. These include chemical shift variations corresponding to different Li+ environments and nuclear quadrupole coupling and relaxation behavior as a probe of Na+ environment.

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Section: Review Of Experimental Resultsmentioning

confidence: 99%

Section: Review Of Experimental Resultsmentioning

confidence: 99%

NMR studies of ion mobility and association in polyether‐based polymer electrolytes

Greenbaum

1993

Polymers for Advanced Techs

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“…With the availability of higher magnetic fields, the less receptive 6 Li nucleus has become an attractive alternative to the more abundant 7 Li spin, whose spectroscopy is complicated by a larger quadrupole constant. 6 Li has been used to study the state of the lithium cation in minerals [10], battery materials [11][12][13], ceramics [14], and glasses [15]. 6 Li, while it is a spin 1 nucleus, has negligible quadrupole couplings; while 6 Li NMR is less sensitive than 7 Li NMR, the absence of substantial homonuclear dipolar and quadrupolar interactions, makes the resolution considerably better ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Preparation of lithium stannide mixtures in organic solvents. A alternate source of lithium in organolithium chemistry

Rieke

Lee

Kye

et al. 2004

Journal of Organometallic Chemistry

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“…It is difficult to attribute this peak to a new complex phase of PEO : Li + = x : 1 (3 < x < 6), or interphase between two complex phases of the 3 : 1 and 6 : 1 complexes. Since O'Gara, et al 15 suggested the existence of the PEO: Li + = 4.2 : 1 complex by analyzing their 6 Li NMR results, we tentatively assign this peak to be the same PEO: Li + = 4.2: 1 complex phase.…”

Section: Resultsmentioning

confidence: 99%

13C CP/MAS and 7Li NMR Study of Lithium Perchlorate/Poly(ethylene oxide)

Asano

Takegoshi

Hikichi

1999

Polym J

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ABSTRACT:To study compositional dependent conductivity of Li +-ions in lithium perchlorate/poly( ethylene oxide) (LiC104 /PEO) electrolytes, mobility of the Li +-ions and morphology of the electrolytes are investigated by examining the spin-lattice relaxation time (T 1 ) of 7 Li and by high-resolution solid-state 13 C NMR methods. It is shown that the amount of the mobile Li+ -ion estimated from the shorter 7 Li-T1 component is not directly compared with the reported conductivity. The high-resolution solid-state 13 C NMR spectra show that there exists five different CH2 carbons in the LiC104 /PEO electrolytes. The five peaks are assigned to ( 1) the crystalline phase of pure PEO, (2) the amorphous phase of PEO with the Li +-ions, and three complex phases of the following ratio of (3) PEO: Li + = 3: 1, (4) x: I (3 < x < 6), and (5) 6: 1. Furthermore, it is shown that the domain size of the PEO: Li + = 6: 1 phase in the LiC104 /PEO = 1/6 electrolyte is large and the mobility of the Li +-ions in the phase is so fast as to give a short 7 Li-T1 comparable to that in the amorphous phase. The former ions are confined in the PEO: Li + = 6: I phase and do not contribute to conductivity while the latter does. Therefore, care should be taken in correlating the amount of the mobile Li +-ions obtained from the 7 Li-T1 data to the Li +-ion conductivity.KEY The polymer electrolyte of poly( ethylene oxide) (PEO) and alkali metal salt exhibits high ion conductivity.1.2 For a LiC104 /PEO electrolyte, when a molar ratio of LiC10 4 to a PEO segment (constitutional repeating EO unit) is less than about 1/10, Li+ -ion conductivity at room temperature reaches to 10-6 S em-1 . 3 -6 Above the concentration of 1/10, the conductivity decreases linearly to the concentration. The observed composition dependence is summarized in Figure 1. ever, as will be shown afterward, ion conductivity depicted in Figure 1 could not directly be related to the amount of the mobile Li +-ions deduced from the 7 Li-T 1 data. This implies that mobility of Li +-ions is affected by the phase structures. It is thus important to clarify the relation between ion conductivity and the phase morphology.The low conductivity at higher Li + concentration has been attributed to the formation of a complex of Li + and PEO. For example, recently, Li et aC examined Li +-ion conductivity in the ternary-system of LiCl0 4 / PEO/poly(2-vinylpyridine) (P2VP). They found that the conductivity depends on the concentration of P2VP, which interferes the formation of PEO: Li + complexes. Apparently, ion conductivity of a LiC10 4 /PEO electrolyte is affected by the phase structure of the system. The PEO: Li + = 6: 1 and 3 : 1 complex phases were suggested for 1/6. 4 • 5 Here, the PEO: Li + = n : 1 means that n segments of PEO (n EO units) form a complex with one Li +-ion. In this work, to examine the structure of the complex phases, the morphology, and the relation between ion conductivity and the phase morphology, we applied solid-state 7 Li and 13 C NMR methods.So far, the 7 Li NMR sp...

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A carbon-13 and lithium-6 nuclear magnetic resonance study of lithium perchlorate/poly (ethylene oxide) electrolytes

Cited by 37 publications

References 14 publications

NMR studies of ion mobility and association in polyether‐based polymer electrolytes

NMR studies of ion mobility and association in polyether‐based polymer electrolytes

Preparation of lithium stannide mixtures in organic solvents. A alternate source of lithium in organolithium chemistry

13C CP/MAS and 7Li NMR Study of Lithium Perchlorate/Poly(ethylene oxide)

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