Nucleophilic cleavage of C-F bonds by Brønsted base for rapid synthesis of fluorophosphate materials.

Fluorochemicals are a rapidly expanding class of materials used in a variety of fields including pharmaceuticals, metallurgy, agrochemicals, refrigerants, and in particular, alkali metal ion batteries. However, achieving one-step synthesis of pure fluorophosphate compounds in a well-controlled manner remains a formidable challenge due to the volatilization of fluorine during the heat treatment process. One feasible method is to cleave the C-F bond in polytetrafluoroethylene (PTFE) during synthesis to create a fluorine-rich atmosphere and strongly reducing environment. However, the inert nature of the C-F bond in PTFE presents a significant obstacle, as it is the strongest single bond in organic compounds. To address this predicament, we propose a fluorine-compensating strategy that involves cleavage of the C-F bonds by nucleophilic S2-type reactions of Brønsted base (ammonia) enabling fluorine compensation. The decomposed products (NH· and C·) also result in the formation of micropores (via NH escape) and carbon coating (via C· polymerization). The resultant cathode delivers a superior potassium storage capability including high rate performance and capacity retention. This contribution not only overcomes the obstacles associated with the inert C-F bond in fluororesin, but also represents a significant step forward in the development of fluorine-containing compounds.