Non-Polar Additive Effect on Solvation Structure in Lithium-ion Battery Electrolytes
- 주제(키워드) Lithium-Ion Battery , solvation structure
- 발행기관 고려대학교 대학원
- 지도교수 곽경원
- 발행년도 2021
- 학위수여년월 2021. 8
- 학위구분 석사
- 학과 대학원 화학과
- 원문페이지 73 p
- UCI I804:11009-000000252149
- DOI 10.23186/korea.000000252149.11009.0001221
- 본문언어 영어
초록/요약
Abstract Lithium-ion batteries (LIBs) are highly demanding batteries among other rechargeable batteries due to its high voltage window and energy density. In the development of lithium-ion batteries, it is important to develop optimized electrolytes because the electrolytes affect determine the properties of Li+ transport, solid electrolyte interphase (SEI) formation. To analyze the properties of the electrolytes and improve its performance, it is important to study the solvation nature of lithium-ion in the electrolytes. Recently, a new method Internally Referenced DOSY-NMR (IR-DOSY) has been reported to investigate the solvation structure in binary systems that is usually complicated to study in IR spectroscopy. In IR-DOSY, since toluene is not directly participating in the first solvation shell, it is used as an internal reference to calculate the solvation ratio of lithium ions in the electrolyte. We have studied the effect of the addition of toluene on the solvation properties of lithium ions in electrolytes by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and NMR spectroscopy. First, we identified how the coordination number changes with the increase in the amount of toluene, and secondly, the increase in the amount of Contact Ion Pair (CIP). Finally, we qualitatively interpret the situation when the amount of toluene increases and verify that it is interacting with Li-ion. In this study, the correlation between the solvent coordination number of lithium-ion and toluene additive in EMC and BC electrolytes is investigated. We believe that this study will expand our understanding of the effect of nonpolar additives on the solvation structure in LIB electrolytes.
more목차
Abstract
Contents
1. Introduction 1
1.1 The general properties and components of LIB electrolytes 2
1.2 Motivation of experiment: non-polar molecules effect on solvation structure 4
2. Experimental Methods 7
2.1 FTIR spectroscopy 8
2.2 Raman spectroscopy 11
2.3 NMR spectroscopy 14
2.4 Sample preparation 17
2.5 Spacer-free thin cell preparation 19
3. Result and Discussion 23
3.1 Sample preparation issue 24
3.2 FTIR spectra of electrolytes 26
3.3 Solvent coordination number of lithium-ion 30
3.4 Free ion and contact ion pair 35
3.5 Chemical shifts 40
4. Conclusion 45
Appendix 49
A.1 50
A.2 51
A.3 52
A.4 53
A.5 54
A.6 55
A.7 56
A.8 57
A.9 58
A.10 59
References 60
