Patent ID: 8062559

Claim:
A method of preparing a cathode active material for lithium secondary batteries comprising: providing a first crystalline substance having one or more members with the general formulas Li x M y (XO 4 ) z , LiMXO 5 , LiMXO 6 and LiMX 2 O 7 , wherein: 0<x/z≦1 and 0≦y/z≦1; M is selected from elements Na, Mn, Fe, Co, Ni, Ti, Nb and V; X is selected from elements P, S, As, Mo and W; providing a second crystalline substance having one or more members with the general formula A a M b N c O d , wherein: A, M and N are different metals selected from groups IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIIB, VIIB and VIII of the periodic table; 0≦a≦6, 0≦b≦6, 0≦c≦6 and 0≦d≦12; wherein a and b cannot both be 0 at the same time; and sintering by solid-state heating the first and second crystalline substances at a temperature ranging from about 500 to 800° C. for a time ranging from about 5 to 32 hours to provide a mixed crystal, wherein the first crystalline substance has a lattice, and at least a part of the second crystalline substance is received by and distributed in the lattice of the first crystalline structure, wherein the mixed crystal has an electrical conductivity ranging from about 0.01 to 10 S/cm at about 25° C.