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

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 LiFePO₄ cathode. This allows the development of innovative high energy density Li metal batteries, such as 3.8 V class Li | LiFePO₄ 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.

SUBMITTER: Park K 

PROVIDER: S-EPMC9685466 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature