Cathode material, method of preparing the same and nonaqueous solvent type secondary battery

A cathode material for a lithium ion secondary battery, especially of the non-aqueous solvent type, comprises a compound of the formula Li1-X-aAXNi1-Y-bBYO2. wherein: A is at least one alkaline earth metal component and may be selected. from (1) at least two of magnesium, calcium, strontium and barium, (2) strontium alone and (3) barium alone; B is at least one transition metal element other than Ni; X is the total number of moles of A and if A consists of more than one alkaline earth metal element, then X is the total number of moles of all alkaline earth metal elements; Y is the total number of moles of B and if B consists of more than one transition metal element, then Y is the total number of moles of all transition metal elements; and X, Y, a and b satisfy the respective equations: A method of preparing the cathode material comprises the steps of: mixing a starting compound containing lithium and A with a starting compound containing nickel and B; heating the mixture in an oxidizing atmosphere.