Open AccessCorrelation between Redox Potential and Solvation Structure in Biphasic Electrolytes for Li Metal Batteries
Author(s) -
Park Kyobin,
Kim DongMin,
Ha KwangHo,
Kwon Bomee,
Lee Jeonghyeop,
Jo Seunghyeon,
Ji Xiulei,
Lee Kyu Tae
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202203443
Subject(s) - solvation , lithium (medication) , electrolyte , inorganic chemistry , ionic liquid , ion , chemistry , metal , lithium metal , anode , solvent , ionic radius , metal ions in aqueous solution , organic chemistry , electrode , catalysis , endocrinology , medicine
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.