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DOE OSTI · 2470265

Correlation between Redox Potential and Solvation Structure in Biphasic Electrolytes for Li Metal Batteries

Park, Kyobin·Kim, Dong‐Min·Ha, Kwang‐Ho·Kwon, Bomee·Lee, Jeonghyeop·Jo, Seunghyeon·Ji, Xiulei·Lee, Kyu Tae
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Abstract

The activity of lithium ions in electrolytes depends on their solvation structures. However, the understanding of changes in Li + activity is still elusive in terms of interactions between lithium ions and solvent molecules. Herein, the chelating effect of lithium ion by forming [Li(15C5)] + gives rise to a decrease in Li + activity, leading to the negative potential shift of Li metal anode. Moreover, weakly solvating lithium ions in ionic liquids, such as [Li(TFSI) 2 ] - (TFSI = bis(trifluoromethanesulfonyl)imide), increase in Li + activity, resulting in the positive potential shift of LiFePO 4 cathode. This allows the development of innovative high energy density Li metal batteries, such as 3.8 V class Li | LiFePO 4 cells, along with introducing stable biphasic electrolytes. In addition, correlation between Li + activity, cell potential shift, and Li + solvation structure is investigated by comparing solvated Li + ions with carbonate solvents, chelated Li + ions with cyclic and linear ethers, and weakly solvating Li + ions in ionic liquids. These findings elucidate a broader understanding of the complex origin of Li + activity and provide an opportunity to achieve high energy density lithium metal batteries.

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25 ENERGY STORAGELi+ activitybatteriescomplexation effectredox potentialsolvation structure

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Park, Kyobin, Kim, Dong‐Min, Ha, Kwang‐Ho, Kwon, Bomee, Lee, Jeonghyeop, Jo, Seunghyeon, Ji, Xiulei, Lee, Kyu Tae. 2022-10-17. Correlation between Redox Potential and Solvation Structure in Biphasic Electrolytes for Li Metal Batteries. https://doi.org/10.1002/advs.202203443

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