Fluorinated carbon nanofibres for high energy and high power densities primary lithium batteries

The electrochemical performances of fluorinated carbon nanofibres have been tested for a use as cathode material in primary lithium battery using LiBF4 PC:DME 1M as electrolyte. For a very narrow fluorination range (420-450 degrees C), the fluorine content in the carbon nanofibres increases up to CF0.78 and so do both the energy and the power densities. A maximum of 8057 W kg(-1) power density has been reached. Moreover, a current density of 6C can be used for such fluorinated carbon nanofibres. Such high electrochemical values can be correlated to the amount of unfluorinated carbon located in the core of the carbon nanofibres. Owing to solid state C-13 NMR which can accurately evaluated this fraction, a minimum of 10% of unfluorinated carbon nanofibre is necessary in order to insure a good conducting behaviour. (C) 2007 Elsevier B.V. All rights reserved.