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Application of surface analytical techniques to the study of the reactivity of lithium toward nonaqueous solvents

by Zhuang, Guorong (Vera)

Abstract (Summary)
Ultra-high vacuum (UHV) surface analytical techniques, such as Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Reflection-absorption Fourier Transform Infrared Spectroscopy (RAFTIRS), have been used to study PC/Li, CO/Au and THF/Au systems which were related to the interests of developing secondary Li batteries. An UHV chamber for simultaneous RAFTIRS and microgravimetric measurements has been designed and constructed to acquire reflection/absorption spectra of nonauqueous solvents adsorbed and/or condensed on metal films vapor deposited in situ on the surface of a quartz-crystal microbalance (QCM). The reactivity of perdeuterated propylene carbonate (d6-PC) toward metallic lithium has been examined in UHV using temperature programmed desorption (TPD). The findings suggest that the most likely product of the reaction between PC and metallic Li is a lithium alkyl carbonate. Experiments in which d6-PC was intentionally mixed with CO2, O2 or H2O showed that in each case the impurity reacts with Li to form the expected products without affecting, aAn UHV chamber for simultaneous RAFTIRS and microgravimetric measurements has been designed and constructed to acquire reflection/absorption spectra of nonauqueous solvents adsorbed and/or condensed on metal films vapor deposited in situ on the surface of a quartz-crystal microbalance (QCM). The reactivity of perdeuterated propylene carbonate (d6-PC) toward metallic lithium has been examined in UHV using temperature programmed desorption (TPD). The findings suggest that the most likely product of the reaction between PC and metallic Li is a lithium alkyl carbonate. Experiments in which d6-PC was intentionally mixed with CO2, O2 or H2O showed that in each case the impurity reacts with Li to form the expected products without affecting, other than the net amount, the d6-PC/Li thermal decomposition pathway. The adsorption of CO on evaporated Au films, Au foil and a Au(111) single crystal was investigated by TPD and RAFTIRS. The results indicated that CO weakly chemisorbed on evaporated Au films and Au foil at liquid nitrogen temperatures. However, CO adsorption on Au(111)was defects related. There existed two types of surface bonding sites; one was IR active and the other was IR inactive. The activation of THF on Au was studied. RAFTIRS provided the evidence that the first monolayer of THF adopted a particular orientation upon adsorption on Au due to specific adsorbate/substrate interactions. This was further supported by TPD measurements which showed that first monolayer and bulk species gave rise to different cracking patterns upon thermal activation
Bibliographical Information:

Advisor:

School:Case Western Reserve University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:lithium nonaqueous solvents analytical techniques

ISBN:

Date of Publication:01/01/1995

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