The present invention relates to a positive electrode composite material for a Li-ion battery, to the preparation method thereof, and to the use thereof in a Li-ion battery. The composite material according to the invention includes: a) at least one conductive additive including carbon nanotubes at a content of between 1 and 2.5 wt %, preferably between 1.5 and 2.2 wt %, relative to the total weight of the composite material; b) an active electrode material capable of reversibly forming an insertion compound with lithium, having an electrochemical potential greater than 2V relative to the Li/Li+ couple, and selected from among compounds having LiMV(XOZ)n polyanionic frameworks; and c) a polymer binder. The positive electrode composite material according to the invention imparts, to the Li-ion battery incorporating said electrode, high support for the cycling capacity, weak internal resistance, and strong charge and discharge kinetics for the moderate cost of the stored KW.