Charge transfer in Li/CFx–silver vanadium oxide hybrid cathode batteries revealed by solid state 7Li and 19F nuclear magnetic resonance spectroscopy

Abstract

Solid state 7Li and 19F magic angle spinning nuclear magnetic resonance (MAS NMR) experiments are conducted on several cathodes containing CFx–Silver vanadium oxide (CFx–Ag2V4O11) hybrid cathodes discharged to 50% depth of discharge (DoD) and stored at their open-circuit voltage for a period of one and three months. Three carbonaceous sources for the CFx phase are investigated: petroleum coke-based, fibrous, and mixed fibrous. For each hybrid cathode, a measurable increase in the relative amount of lithium fluoride is observed after a three month resting period in both the 7Li and 19F NMR spectra. These changes are attributed to lithium ion migration from the silver vanadium oxide to the CFx phase during the resting period, and help clarify the mechanism behind high power handling capability of this cathode.