When treated at high temperatures, petroleum coke materials exhibit structures which are formed of graphitized closed tips. The external surface of these materials is mostly formed of hemispherical tips similar to those found in carbon nanotubes. By low- temperature fluorination using CF4 radio- frequency plasmas, an opening mechanism of the closed tips occurs, thus allowing a drastic increase of possible intercalation into the structure. The interest for Li+ storage in Li-ion batteries has been demonstrated by capacity measurements which show an enhancement of the Li+ capacity retention into the host materials. (c) 2007 The Electrochemical Society.