Interactions among solvent, anion acceptor, and supporting electrolyte salt in fluoride shuttle battery electrolyte based on nuclear magnetic resonance

Fluoride shuttle batteries (FSBs) are promising next-generation rechargeable batteries. To analyze the detailed local environment in the electrolytes of FSBs, the dynamics of the molecules and ions in an electrolyte, prepared using 2, 4, 6-trimethoxyboroxine (TMBX)-a liquid-type anion acceptor, were investigated using nuclear magnetic resonance. The results indicated that TMBX could be mixed with the solvent (bis[2-(2-methoxyethoxy)ethyl]ether (tetraglyme, G4)); however, it did not interact with G4. In contrast, when cesium fluoride (CsF) was added to TMBX/G4, TMBX interacted with CsF, and a TMBX-F- ion was formed. TMBX-F- interacted and cooperatively diffused with G4.