Biphasic Electrolyte Inhibiting the Shuttle Effect of Redox Molecules in Lithium Metal Batteries.

Redox molecules (RMs) as the electron carriers have been widely used in electrochemical energy storage devices (ESDs), such as lithium-redox flow batteries and lithium-O 2  batteries. Unfortunately, the migration of RMs to Li anode leads to the side reaction between them, resulting in the reduced coulombic efficiency and early cell death. Herein, a proof-of-concept study that a biphasic organic electrolyte is constructed to settle down this issue, in which nonafluoro-1,1,2,2-tetrahydrohexyl-trimethoxysilane (NFTOS) and ether (or sulfone) with LiTFSI can be separated to form the immiscible anolyte and catholyte. RMs are extracted to the catholyte due to the enormous solubility coefficients in the biphasic electrolyte with high and low polarity, resulting in the inhibition of shuttle effect. When coupling with lithium anode, the Li-Li symmetric, Li-redox flow and Li-O 2  batteries can achieve considerably prolonged cycle life with the biphasic electrolytes. This concept provides a promising strategy to suppress the shuttle effect of RMs in their wide application in ESDs.