TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The operational voltage of the cathode active material is greater than or equal to 4.3V.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The lithium metal oxide composite comprises a domain having a crystal structure in which a lattice constant c of a length of a c-axis is greater than or equal to 14.24 Angstrom . The ratio of a peak intensity of a primary peak corresponding to a 003 plane to a peak intensity of a secondary peak corresponding to a 104 plane in an X-ray diffraction spectrum of the lithium metal oxide is greater than or equal to 1.3. The particle size of crystalline particles of the lithium metal oxide composite, when determined by analysis of a full width at half maximum of a peak corresponding to an 003 plane in an X-ray diffraction spectrum, is greater than or equal to 80 nm. The separation distance between a peak corresponding to a 108 plane having a scattering angle of 64.5 degrees plus minus 0.5 degrees two-theta and a peak corresponding to a 110 plane having a scattering angle of 65.5 degrees plus minus 0.5 degrees two-theta in an X-ray diffraction spectrum of the lithium metal oxide composite is greater than or equal to 0.8 degrees . The first domain is of formula Li2-y(M1)1-z(M2)y+zO3 (II). The second domain is of formula LiMeO2 (III). The first lithium precursor and the second lithium precursor each independently comprise at least one lithium salt selected from Li2CO3, LiOH, Li(CO2)2, LiCl, LiOCO2CH3, and LiF. The transition metal precursor comprises at least one selected from MnCO3, Mn(SO4)2, Mn(NO3)2, MnCl2, MnBr2, (CH3CO2)2Mn, NiCO3, NiSO4, NiNO3, NiCl2, NiBr2, (CH3CO2)2Ni, CoCO3, CoSO4, Co(NO3)2, CoCl2, CoBr2, (CH3CO2)2Co, FeCO3, FeSO4, Fe(NO3)2, Fe(NO3)3, FeCl2, FeCl3, FeBr2, FeBr3, (CH3CO2)2Fe, CrCO3, Cr(SO4)2, Cr(NO3)2, CrCl2, CrBr2, (CH3CO2)2Cr, and its hydrate. The metal dopant precursor comprises at least one selected from Al2O3, MgO, V2O5, VO2, V2O3, VO, ZnO, MoO3, Nb2O3, La2O3, and RuO2. The metal precursor comprises at least one selected from NiCO3, Ni(SO4)2, Ni(NO3)2, NiCl2, NiBr2, (CH3CO2)2Ni, MnCO3, Mn(SO4)2, Mn(NO3)2, MnCl2, MnBr2, (CH3CO2)2Mn, CoCO3, Co(SO4)2, Co(NO3)2, CoCl2, CoBr2, (CH3CO2)2Co, FeCO3, FeSO4, Fe(NO3)2, Fe(NO3)3, FeCl2, FeCl3, FeBr2, FeBr3, (CH3CO2)2Fe, CrCO3, Cr(SO4)2, Cr(NO3)2, CrCl2, CrBr2, (CH3CO2)2Cr, TiCO3, Ti(SO4)2, Ti(NO3)2, TiCl2, TiBr2, CuCO3, CuSO4, Cu(NO3)2, CuCl2, CuBr2, (CH3CO2)2Cu, AlCO3, Al(SO4)3, Al(NO3)3, AlCl3, AlBr3, (CH3CO2)3Al, MgCO3, MgSO4, Mg(NO3)2, MgCl, MgBr, (CH3CO2)2Mg, Zr(CO3)2, Zr(SO4)2, Zr(NO3)2, ZrCl4, ZrBr4, B2(CO3)3, B2(SO4)3, B(NO3)3, BCl3, BBr3, and its hydrate. Preferred Method: The amount of the metal dopant precursor is 0.01-0.5 mole%. The first thermal treatment is performed at 400-800 degrees C. The second thermal treatment is performed at 700-950 degrees C. The method further involves mechanically milling the first domain lithium metal oxide, and mechanically milling the lithium metal oxide composite (I). EXAMPLE - A Li2CO3, MnCO3, and Al2O3 were mixed and then ground with grinding media, i.e., balls, in a grinding container for 1 hour. The ground mixture underwent a first thermal treatment in a furnace, in which dry air was supplied to it at 600 degrees C for 12 hours and at a temperature of 800 degrees C for 12 hours, to prepare the first domain lithium metal oxide (0.5(Li1.9375MnAl0.0625O3)). A Li2CO3 and NiCoMn(OH)2 were mixed with the first domain lithium metal oxide and with balls, followed by grinding of the mixture in a grinding container for 1 hour based on a mole ratio of Li:Ni:Co:Mn. The ground mixture underwent a second thermal treatment in a furnace, in which dry air was supplied to it at a temperature of 900 degrees C for 10 hours, to prepare 0.5(Li1.9375MnAl0.0625O3)-0.5(Li(Ni0.33Co0.33Mn0.33)O2) (cathode active material).