NOVELTY - Preparing (M1) a cathode active material for lithium secondary batteries involves providing a first crystalline substance; providing a second crystalline substance; and sintering the two crystalline substances at 500-800 degrees C for 5-32 hours to provide a mixed crystal, the mixed crystal having electrical conductivity of 0.01-10 S/cm at 25 degrees C.    USE - For preparing a cathode active material for lithium secondary batteries (claimed) used in various devices such as laptop, camera, camcorder, personal digital assistant (PDA), cell phone, iPod and other portable electronic devices; and also used in defense, automotive and aerospace applications.    ADVANTAGE - The mixed crystal having electrical conductivity of 0.01-10 S/cm at 25 degrees C. The cathode active material for lithium secondary batteries provides superior electrical performance, e.g. higher electrical conductivity, discharge capacity and discharge capacity maintenance or retention rate.    DETAILED DESCRIPTION - Preparing (M1) a cathode active material for lithium secondary batteries involves providing a first crystalline substance having at least one members of formulae LixMy(XO4)z, LiMXO5, LiMXO6 and LiMX2O7; providing a second crystalline substance having at least one members of formula AaMbNcOd; and sintering the two crystalline substances at 500-800 degrees C for 5-32 hours to provide a mixed crystal, the mixed crystal having electrical conductivity of 0.01-10 S/cm at 25 degrees C.    x/z and y/z=0-1    M=sodium (Na), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), titanium (Ti), niobium (Nb) or vanadium (V);    X=phosphorus (P), sulfur (S), arsenic (As), molybdenum (Mo) or tungsten (W);    A, M and N=metals selected from groups IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIB, VIIB and VIII of the periodic table;    a, b and c=0-6;    d=0-12.    (where a and b both cannot be 0 at the same time). An INDEPENDENT CLAIM is included for a method (M2) of providing a lithium secondary battery involving providing electrodes having wounded or stacked cathode, anode and divider film, the cathode comprising the cathode active material; and providing a battery case and electrolyte, the electrodes and electrolyte adaptable to being sealed within the battery case.