An Analysis of the Thermal Decomposition Reactions of Organic Electrolytes Used in Lithium-Ion Batteries

Author

Christopher Lawrence Campion, University of Rhode Island

Date of Award

2005

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry

Department

Chemistry

First Advisor

Brett Lucht

Abstract

The thermal decomposition of LiPF₆ in solution with carbonate solvents has been investigated. The thermal dissociation of LiPF₆ into LiF and PF₅ is known. In solution, PF5 reacts with carbonates to form a variety of decomposition products including: carbon dioxide (CO₂), ethers (R₂O), alkylfluorides (RF), phosphorus oxyfluoride (OPF₃), and fluorophosphates (OPF₂OR, OPF(OR)₂), assignment of structure is supported by Nuclear Magnetic Resonance (NMR) spectroscopy and Gas Chromatography with Mass Selective Detection (GC-MS). Similar decomposition products are observed during the thermal decomposition of carbonate solutions of LiPF₆. Since solutions of LiPF₆ are widely used as Li-ion battery electrolytes, there is interest among battery manufacturers and researchers as to the thermal decomposition of this electrolyte. Here we describe the structural and mechanistic investigations of the thermal decomposition of lithium-ion battery electrolytes. The electrolyte undergoes autocatalytic decomposition reactions at moderately elevated temperatures (80-100 °C) to produce a large number of decomposition products. Results indicate that the thermal decomposition reactions are suppressed by the electrode, particularly the cathode, or intended stabilizing additives.

Recommended Citation

Campion, Christopher Lawrence, "An Analysis of the Thermal Decomposition Reactions of Organic Electrolytes Used in Lithium-Ion Batteries" (2005). Open Access Dissertations. Paper 1585.
https://digitalcommons.uri.edu/oa_diss/1585