Fluorinated graphene nanoribbons from unzipped single-walled carbon nanotubes for ultrahigh energy density lithium-fluorinated carbon batteries

Abstract

Lithium-fluorinated carbon (Li-CFx) batteries have become one of the most widely applied power sources for high energy density applications because of the advantages provided by the CFx cathode. Moreover, the large gap between the practical and theoretical potentials alongside the stoichiometric limit of commercial graphite fluorides indicates the potential for further energy improvement. Herein, monolayer fluorinated graphene nanoribbons (F-GNRs) were fabricated by unzipping single-walled carbon nanotubes (SWCNTs) using pure F2 gas at high temperature, which delivered an unprecedented energy density of 2738.45 W h kg−1 due to the combined effect of a high fluorination degree and discharge plateau, realized by the abundant edges and destroyed periodic structure, respectively. Furthermore, at a high fluorination temperature, the theoretical calculation confirmed a zigzag pathway of fluorine atoms that were adsorbed outside of the SWCNTs and hence initiated the spontaneous process of unzipping SWCNTs to form the monolayer F-GNRs. The controllable fluorination of SWCNTs provided a feasible approach for preparing CFx compounds for different applications, especially for ultrahigh energy density cathodes.