Optimized electrolyte design to form a solid electrolyte interphase with high mechanical strength in Si-anode batteries
- 주제(키워드) Lithium-ion batteries , silicon-based electrode , electrolyte , interfacial chemistry
- 발행기관 고려대학교 대학원
- 지도교수 강윤찬, 김도엽
- 발행년도 2025
- 학위수여년월 2025. 2
- 학위명 석사
- 학과 및 전공 대학원 신소재공학과
- 원문페이지 71 p
- 실제URI http://www.dcollection.net/handler/korea/000000291564
- UCI I804:11009-000000291564
- DOI 10.23186/korea.000000291564.11009.0001892
- 본문언어 영어
초록/요약
Lithium-ion batteries (LIBs) are regarded as the most promising candidates for meeting the increasing demand for future energy storage. To innovate emerging commercial applications such as electric vehicles (EVs), LIBs desperately need to provide high energy densities and long-term cycle lifetimes. As for high energy density anodes, silicon (Si) has been considered as a promising replacement to the commercial graphite-based anode materials due to its high theoretical capacities (3579mAh g-1 for Li15Si4 at room temperature) and low lithiation potential (<0.4V vs Li/Li+). However, the practical implement Si-based anodes is hindered by the significant volume expansion of silicon particles during cycles, triggering unstable solid electrolyte interphase (SEI) and thereby the fast capacity fading in electrolytes. Optimization of the electrolyte are crucial to form a stable SEI, which contribute to improve the overall electrochemical performance of Si-based anode. Current commercial electrolytes mostly rely on lithium hexafluorophosphate (LiPF6) in a mixture of carbonate solvent, contributing to the formation of a rich organic SEI. However, LiPF6 salt exhibits poor stability at high temperature or in the presence of small amount of water. To enable stable cycling of LIBs with Si-based anode, optimized electrolytes were introduced. Herein, a TEP-FEC-based electrolyte is designed and shows high compatibility with Si anodes. The use of TEP is improved the oxidation stability of dual-salt (LiFSI-LiPF6) electrolyte and FEC is well-known for enhancing the interfacial stability of Si-based electrodes. This strategy enables the electrolyte to form a highly elastic, robust inorganic-polymeric interphase on Si electrodes that can tolerate the immense volume changes. The Si electrode using the TF-control electrolyte retains up to 79.8% of its initial capacity after 170 cycles at 0.5C, outperforming those in the commercial electrolytes.
more목차
CHAPTER 1. INTRODUCTION 15
1.1 Lithium-ion Batteries (LIBs) 15
1.2 Silicon anode 18
1.3 Electrolyte for Silicon anode 21
1.4 Objective of this study 24
CHAPTER 2. Experimental 25
2.1 Material 25
2.1.1 Preparation of Electrode 25
2.1.2 Preparation of Electrolyte 25
2.2 Characterization 26
2.3 Electrochemical Measurements 26
CHAPTER 3. Result & Discussion 28
3.1 Design of electrolytes 28
3.2 Stability test of LiFSI and LiPF6 30
3.3 Electrochemical test 34
3.4 Electrochemical performances of Si/Li half-cell 40
3.5 Morphological evolution of Si electrodes 46
3.6 XPS and TOF-SIMS analysis of Si anode after 50 cycles 53
3.7 Ion desolvation energy and Raman analysis of electrolytes 61
3.8 NCM811 l Si full cell test 64
CHAPTER 4. CONCLUSIONS 67
REFERENCES 68
