Fluorinated graphite materials described by the chemical formula (CFx)n (0 &lt; x &lt; 1.25), continue to attract interest for a wide range of electrochemical energy applications. In this presentation extensive DFT (density functional theory) computational studies for the fully fluorinated (CF)n material is combined with solid state 13C and 19F MAS (magic angle spinning) NMR spectroscopy in order to extract the very rich structural information contained within the experimental results. DFT calculations show that the presence of structural disorder and local defects within the (CF)n materials provide distinct NMR chemical shift signatures and allow development of models for the mean local structure that reflect the disorder inherent in synthesized fluorinated graphite materials. NMR characterization of multiple (CF)n samples shows that the types and extent of disorder varies between them. Through a combination of 2D 19F-19F NMR exchange and 2D NMR correlation experiments it is also possible to identify increased conformational order near the (CF)n platelet edges along with the existence of different fluorinated platelet edge environments and dynamics. The impact of these defects and structural disorder on the corresponding C-F bond energetics and electrochemical performance of (CF)n materials is also presented and discussed.

Characterizing disorder and defect structures in fluorinated graphite using NMR

ACS Fall 2021

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