Polypyrrole-coated Graphite Fluorides with High Energy and High Power Densities for Li/CF battery

Polypyrrole (PPy) coated graphite fluorides (CFx) composites have been prepared via in situ chemical oxidative polymerization. The influence of coating thickness on the electrochemical performances of PPy-coated CFx (CFx@PPy) cathodes has been investigated. The results show that the rate capability of CFx@PPy cathodes are improved compared with that of pristine CFx cathode. The PPy coating serves as the path for charges transfer from the surface of CFx to the reaction interface. The conductivity of CFx@PPy increases with the growing PPy coating, however, too thick PPy coating may inhibit the lithium ions transfer and even pull down the discharge capacity. Finally, the CFx@PPy composite with a PPy coating thickness of 80 nm exhibits a superior rate capability and a maximum delivered power density up to 7091 W kg-1 at 6 C.