13C NMR Spectroscopic, CV, and Conductivity Studies of Propylene Carbonate-Based Electrolytes Containing Various Lithium Salts

Abstract

The ion-solvent and ion-ion interactions, oxidative electrochemical stabilities, and ionic mobilities of a series of lithium salt electrolytes with commonly used electrolyte solvents, propylene carbonate (PC) and dimethyl carbonale (DMC), have been studied using 13C nuclear magnetric resonance (NMR) spectroscopy, cyclic voltammetry (CV), and ionic conductivity measurements. The coordinating ability of PC toward lithium salts is significantly higher than that of DMC as shown by the relatively large deshielding of the carbonyl carbon of PC over that of DMC. We have also prepared a novel electrolyte, lithium tetrakis(trifluoromethanesulfonato)gallate [LiGa(OTf)4], and investigated its relative binding to PC by 13C NMR spectroscopy. The latter salt showed significant deshielding of the carbonyl carbon of PC compared to the other salts studied, including the conventional LiPF6. However, its conductivity is not enhanced to the same extent and is comparable to that of LiBF4. The CVs show their relative stabilities toward oxidation around 4.5 V and reduction close to lithium potentials. All electrolytes studied here have good electrochemical stability from 0.1 to 5.0 V vs. Li+/Li, and are suitable for applications in lithium-ion cells.

Department(s)

Chemistry

Sponsor(s)

Petroleum Research Fund

Keywords and Phrases

Cyclic voltammetry; Electrochemistry; Electrolytes; Lithium compounds; Propylene; Salts; Carbonate-based electrolytes; Ion-ion interactions; Lithium salts; Nuclear magnetic resonance; Organic compounds; Oxidation; Reduction (Chemistry)

International Standard Serial Number (ISSN)

1099-0062

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2005 the Electrochemical Society (ECS), All rights reserved.

Publication Date

01 Apr 2005

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