Fluorination regulates heat generation in Ah-level lithium/fluorinated carbon pouch cells

The fluorination temperature not only influences the F/C ratio, but also the C–F bonding configuration, and physicochemical properties of the FPC. Pouch cells using the more highly fluorinated cathodes generated the most heat during discharge. The heat generated also has a clear stage dependence, with the largest difference appearing in the 0–20% depth of discharge range.

Post-discharge structural characterization and kinetic analysis showed that the highly fluorinated FPC cathodes show more LiF accumulation more concentrated in certain regions, together with a higher charge-transfer resistance, stronger polarization, lower Li+ diffusivity, and a higher nucleation overpotential. These factors collectively intensify the early-stage heat generation in the cells. This study shows that the fluorinated cathode structure, LiF evolution, and discharge kinetics jointly govern heat generation in Li/FPC pouch cells, possibly providing a way to improve their thermal safety.