TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The primary particles of the small particle active material comprise particles having a size of 5-200 nm. The small particle active material is present at 10-60 wt.%. The secondary particles included in the small particle active material are present at 30-100 wt.%, and further comprise a conductive agent in addition to the primary particles, where the conductive agent is present at 0.5-5 wt.% and a mixture of at least one carbon black including acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black or a material having a crystal structure of graphene or graphite. The small particle active material is olivine-structured lithium-containing phosphate of formula (LiM1aPO4), preferably lithium iron phosphate. The composite electrode further comprises: ternary lithium-containing metal oxide of formula (LiNixMnyCo1-x-yO2) in addition to lithium iron phosphate, preferably lithium nickel cobalt manganese oxide (Li(Ni1/3Co1/3Mn1/3)O2); and a mixture of at least one lithium cobalt oxide, lithium nickel oxide, lithium cobalt-nickel oxide, lithium cobalt-manganese oxide, lithium manganese-nickel oxide, lithium cobalt-nickel-manganese oxide, lithium-containing olivine-type phosphate, and oxides having other elements substituted or doped in it, and the other elements are at least one element comprising aluminum, magnesium, manganese, nickel, cobalt, chromium, vanadium, and iron. The composite electrode comprises a binder and a conductive agent at less than or equal to 10 wt.%.M1a = at least one Co, Ni, Mn or Fe; andx, y = greater than 0 to less than 0.5. EXAMPLE - 60 wt.% Lithium nickel cobalt manganese oxide (Li(Ni1/3Co1/3Mn1/3)O2), 20 wt.% material (in which lithium iron phosphate secondary particles and general lithium iron phosphate were mixed in a ratio of 50:50), 1 wt.% graphite and 7 wt.% Denka black (RTM: Carbon black) were ground and sieved, and then coated with 6 wt.% of polyvinylidene fluoride as a binder to prepare a cathode material. Cathode current collector was coated with the cathode material, and then rolled and dried to prepare a cathode for a secondary battery.