High-Power-Density, High-Energy-Density Fluorinated Graphene for Primary Lithium Batteries.

Li/CF is one of the highest-energy-density primary batteries; however, poor rate capability hinders its practical applications in high-power devices. Here we report a preparation of fluorinated graphene (GF) with superior performance through a direct gas fluorination method. We find that the so-called "semi-ionic" C-F bond content in all C-F bonds presents a more critical impact on rate performance of the GF in comparison with sp C content in the GF, morphology, structure, and specific surface area of the materials. The rate capability remains excellent before the semi-ionic C-F bond proportion in the GF decreases. Thus, by optimizing semi-ionic C-F content in our GF, we obtain the optimal x of 0.8, with which the GF exhibits a very high energy density of 1,073 Wh kg and an excellent power density of 21,460 W kg at a high current density of 10 A g. More importantly, our approach opens a new avenue to obtain fluorinated carbon with high energy densities without compromising high power densities.