Date of Award

2011

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Brett Lucht

Abstract

Lithium-ion batteries (LIBs) are one of the most widely used energy sources, especially for portable electronics. However, the development of lithium ion batteries for Electric Vehicle (EV) and Plug-in Hybrid Electric Vehicle (PHEV) requires the research and development of improved electrolytes. The development of electrolytes which allow LIBs to perform over a wide temperature range and operating potential are of significant current interest. The interphase formed on the surface of the electrodes generally governs kinetics of charging and discharging and is an important factor in life of LIBs. Favorable electrode interphases can be generated by altering the composition of the electrolyte.

Commercially available LIBs have a normal discharge voltage around 3.7V where the electrolyte oxidation on the surface of cathodes is not a significant problem. Recent research in high voltage cathode materials (>4.5 V vs Li/Li+) to increase the power and energy density of LIBs for EV applications has raised concerns about the stability of LiPF6/carbonate based electrolyte to oxidation. Furthermore, the flammability of organic electrolyte hinders LIBs’ application in the EV market. Detailed investigations of improved electrolyte systems which can address the above issues will be presented. Components of the interphase are detected using various surface analysis techniques such as XPS, FTIR and SEM.

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