Addressing electrode degradation issue in high negative to positive electrode capacity ratio lithium-ion batteries using water-in-salt electrolyte
- Authors
- Zhanadilov, Orynbay; Akhmetova, Aktilek; Son, Junehyuk; Yu, Jun Ho; Kim, Mingony; Chung, Kyung Yoon; Kim, Hee Jae; Bakenov, Zhumabay; Yashiro, Hitoshi; Myung, Seung-Taek
- Issue Date
- 2025-06
- Publisher
- SPRINGER NATURE
- Citation
- Advanced Composites and Hybrid Materials, v.8, no.3
- Abstract
- In this study, we investigate the underlying causes of degradation in Li4Ti5O12//LiMn2O4 cells with an N/P ratio of 0.9 utilizing 19.44 m LiN(SO2CF3)(2) and 8.33 m LiN(SO2CF2CF3)(2) (Li(TFSI)(0.7)(BETI)(0.3)center dot 2H(2)O), a hydrate-melt electrolyte. We identify the formation of hydrofluoric acid (HF) during electrochemical reactions as a key factor leading to both Mn dissolution from the LiMn2O4 cathode and rapid self-discharge at room temperature. To address these challenges, we apply a calcium fluoride (CaF2) coating to the electrodes, designed to scavenge HF by reacting to form calcium bifluoride (Ca(HF2)(2)). This reaction underscores the unique quasi-non-aqueous nature of Li(TFSI)(0.7)(BETI)(0.3)center dot 2H(2)O, which facilitates chemical processes not possible in traditional aqueous electrolytes. Electrochemical evaluations demonstrate that the CaF2-coated electrode exhibits improved capacity retention and higher coulombic efficiency than their uncoated counterparts. Despite these enhancements, the rapid self-discharge issue remains, indicating that additional factors contribute to this phenomenon and require further investigation. Our findings highlight the potential of water-in-salt systems, particularly the Li(TFSI)(0.7)(BETI)(0.3)center dot 2H(2)O electrolyte, in advancing lithium-ion battery technology by leveraging their distinct chemical environment. This study provides insights into the mechanisms affecting the stability and performance of hydrate-melt electrolyte for exploiting quasi-non-aqueous systems in energy-storage applications.
- Keywords
- LIMN2O4 CATHODE; CHEMISTRY; STATE; SAFE; SELF-DISCHARGE; Hydrate-melt electrolyte; Lithium-ion batteries; HF formation; Mn dissolution; CaF2 coating; Water-in-salt electrolyte
- ISSN
- 2522-0128
- URI
- https://pubs.kist.re.kr/handle/201004/152681
- DOI
- 10.1007/s42114-025-01347-5
- Appears in Collections:
- KIST Article > Others
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