Patent ID: 8404381

Claim:
A method for preparing a compound having a spinel structure, said compound having a mesh parameter of between 8.174 and 8.179 Å, and a particle size of between 5 and 10 μm, and said compound having the formula Li y Ni 0.5 Mn 1.5−x IV Mn x III A z O 4−d , wherein: 0.02≦x≦0.35; d>0; A is selected from the group consisting of Na, K, Mg, Nb, Al, Ni, Co, Zr, Cr, Fe, Cu, Ti, Zn, Si and Mo; 0.8≦y≦1.2; and 0≦z≦0.1; wherein said method comprises: forming a mixture by mixing lithium, nickel and manganese based precursor with a lithium excess of 1 to 5 mol%; subjecting the mixture to a first heat treatment at a first temperature of between 550 and 600° C. for a time sufficient to permit incorporation of the lithium with the nickel and manganese based precursor; and after the first heat treatment, subjecting the mixture to a second heat treatment at a second temperature above 700° C. for a time sufficient to cause a loss of oxygen, combined with a cooling in oxygen containing medium at a rate sufficient to permit a partial oxygen return; and wherein the said compound is made by the said method.