Dissertation Defense: Radiation-Induced Material and Performance Degradation of Electrochemical Systems

Committee Members

• Dr. Lei R. Cao, Chair (MAE)
• Dr. Anne C. Co (Chemistry)
• Dr. Jung Hyun Kim (MAE)

Abstract

Lithium Ion Batteries (LIBs) are widely used in research, industry and households, especially in autonomous systems, thanks to their large capacity, sustainability and good cycling ability. Research on LIBs materials and performance has been done through recent decades. Many kinds of cathode, electrolyte and anode materials have been discovered and several configurations (for instance coin cells, cylinder cells, and prismatic cells with varying sizes) have been developed for different operating conditions. Devices equipped with LIBs may operate under extreme conditions with radiation, moisture or high temperature. The performance of LIBs in these environments is crucial to sustained operations of these systems. While LIBs are usually commercially packed to avoid moisture exposure, the other two factors cannot be easily addressed because of penetrating effects. While temperature effects have been explored thoroughly, in this study, we are targeting material and performance degradation and reliability of a LIB when operating in radiation environments. These scenarios include powering instruments and equipments in hot cells, performing rescue or sampling missions at post-nuclear accidents. The overarching goal of this study is to provide a potential design for LIBs operating in extreme conditions. Battery performance with irradiated components was first examined. And an ex-situ irradiation-testing protocol was then conducted, investigating the correlation between battery cyclability and the cumulative dose. An in-situ methodology to monitor LIB performance degradation when operating (cycling) under gamma radiation with a post-accident dose rate (30 krad h\textsuperscript{-1}) was carried out, and it provided results in terms of capacity fade and impedance rise. Individual battery components were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, ultraviolet–visible spectroscopy (UV-vis) and nuclear magnetic resonance (NMR) to examine their response to various radiation dosages. Most importantly, this study focused on damage to electrolyte from gamma radiation. Gas chromatography-mass spectroscopy (GC-MS) was utilized to investigate the time dependent effects developed days and weeks after the electrolyte was irradiated. Lastly, alternative electrolytes were proposed for batteries in radioactive and high temperature environments. Radiation-induced decomposition was examined by GC-MS and batteries with irradiated ionic-liquid-based electrolyte were assembled and tested. Batteries with ionic-liquid-based electrolyte four months post-irradiation, despite being decomposed by direct exposure to gamma radiation, showed good performance comparing to batteries with non-irradiated ionic-liquid-based electrolyte.