Graphite material for negative electrode of lithium ion secondary battery and process for producing the same

Abstract

According to the present invention, milled carbon fiber is mixed with a boron compound and graphitized in the presence of nitrogen, and thereafter subjected to modifying treatment by applying impact selectively to fiber edge parts of the carbon fiber. The present invention can provide a graphite material produced in such a way that the milled carbon fiber is highly graphitized and the fiber edge parts of the graphitized milled carbon fiber is subjected to a modifying treatment in the above procedure. The graphite material is suitable for a negative electrode of a lithium secondary battery capable of facilitating entering and leaving (doping and undoping) of lithium ions, having large discharge capacity and high charge/discharge efficiency and excellent charge/discharge cyclability. The present invention also provides a process for producing such graphite materials.

Dependencies are inferred from the claim text.