Fluorinated graphene (FG) has been a star material as a new derivative of graphene. In this paper, a series of fluorinated graphene materials are prepared by using N, O-doped graphene aerogel as precursor via a direct fluorination method, and the effect of fluorination temperature on the FG structure is investigated. The prepared FG samples are systematically characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. It is found that the structure of FG, including features such as layer size, chemical composition, chemical bond state of the component elements, etc., is significantly related to the fluorination temperature. With the change of the fluorination temperature, fluorine atoms enter the graphene framework by a substitution process of the N, O-containing groups, including residual phenol, ether, carbonyl groups, or C–N groups, and the addition to CC bonds, subsequently forming a fluoride with different fluorine contents. The fluorine content increases as the fluorination temperature increases from 200 °C to 300 °C, but decreases at a fluorination temperature of 350 °C due to the decomposition of the fluorinated graphene. The prepared FG samples are used as cathode material for lithium primary batteries. The FG sample prepared at 300 °C gives a high specific capacity of 632 mAh g⁻¹ and a discharge plateau of 2.35 V at a current density of 10 mA g⁻¹, corresponding to a high energy density of 1485 Wh kg⁻¹.

The Lithium sulfur (Li-S) battery has a great potential to replace lithium-ion batteries due to its high-energy density. However, the “shuttle effect” of polysulfide intermediates (Li₂S₈, Li₂S₆, Li₂S₄, etc.) from the cathode can lead to rapid capacity decay and low coulombic efficiency, thus limiting its further development. Anchoring polysulfide and inhibiting polysulfide migration in electrolytes is one of the focuses in Li-S battery. It is well known that polar metal oxides-manganese oxides (MnO₂) are normally used as an effective inhibitor for its polysulfide inhibiting properties. Considering the natural 1D tunnel structure, MnO₂ with three kinds of typical tunnel-type were screened to study the effects of the tunnel size on the adsorption capacity of polysulfide. We found that MnO₂ with larger tunnel sizes has stronger chemisorption capacity of polysulfide. It promotes the conversion of polysulfide, and corresponding cathode exhibits better cycle reliability and rate performance in the cell comparison tests. This work should point out a new strategy for the cathode design of advanced Li-S battery by controlling the tunnel size.