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Abstract

A novel method of preparing a spinel Li.sub.1+X Mn.sub.2-X O.sub.4+Y intercalation compound with low lattice distortion and a highly ordered and homogeneous structure for 4 V secondary lithium and lithium ion cells is provided. The method of preparing the spinel Li.sub.1+X Mn.sub.2-X O.sub.4+Y intercalation compound comprises providing a spinel Li.sub.1+X Mn.sub.2-X O.sub.4 intercalation compound having a lithium to manganese mole ratio of between about 1.02:2 and 1.1:2 and firing the spinel at different temperature ranges with corresponding gas flow rates to form the spinel Li.sub.1+X Mn.sub.2-X O.sub.4+Y intercalation compounds. The spinel Li.sub.1+X Mn.sub.2-X O.sub.4+Y intercalation compounds have a mean X value of between about 0.01 and 0.05, a mean Y value of between about -0.02 and 0.04 and a full width at half maximum of the x-ray diffraction peaks at a diffraction angle 2.theta. of planes (400) and (440) using CuK.alpha..sub.1 rays of between about 0.08.degree. and 0.13.degree.. The spinel Li.sub.1+X Mn.sub.2-X O.sub.4+Y intercalation compounds may be used in the positive electrodes of secondary lithium and lithium ion cells to provide cells having high specific capacities and long cycling lives.

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