UV-radiation inducing strategy to tune fluorinated carbon bonds delivering the high-rate Li/CFx primary batteries

Abstract Li/CFx batteries are widely applied in medical and electronic products because of their outstanding electrochemical performance. However, the poor intrinsic conductivity and inevitable polarization of the CFx material result in low ion migration and rate performance. Herein, an ultraviolet (UV)-radiation inducing technology to adjust the C–F bonding types, which improved the rate performance of the Li/CFx battery. UV radiations reasonably change the ratio of various C–F bonds, namely, not only increased the concentration of semi-ionic C–F bonds, but also reduced the relative proportion of inert C–F2 and inactive C–F3. Then this technology further increases the conductivity of the CFx and improves the rate performance of Li/CFx batteries. After UV-modification, the CFx possesses more multi-level channels to favor the electrolyte infiltration, shortening the charge transmission distance. And the in situ formed carbon coating also contributes to the enhanced conductivity. Compared with the original FSC losing the discharge capacity at 1 C, the optimal FSC-5W-72h has a specific capacity of 762.1 mAh/g and a specific energy of 1615.4 Wh/kg at 1 C. This UV radiation technology has created a novel way to address the reasonable C–F bonds of CFx and in-situ carbon coating, improving the rate performance of Li/CFx battery.