New LiNi[sub y]Co[sub 1−2y]Mn[sub 1+y]O[sub 4] Spinel Oxide Solid Solutions as 5 V Electrode Material for Li-Ion Batteries

New mixed spinel oxides with LiNi y Co 1 − 2 y Mn 1 + y O 4 ( y = 0.2 , 0.3, and 0.4) stoichiometries have been synthesized under different annealing temperatures and tested as cathode materials in lithium batteries. High-purity cubic spinel-phase products were obtained between 700 and 950°C, in which the lattice parameter increases with nickel content. The structural and textural properties of the powder samples were studied by X-ray diffraction (XRD) and scanning electron microscopy and correlated with the electrochemical behavior. From these experiments, the best performance was obtained for LiNi 0.4 Co 0.2 Mn 1.4 O 4 cathodes with 1-5 μm regular octahedral particles, which developed capacity values close to 120 mAh/g with a good capacity retention. The ex situ XRD patterns of the partially charged electrodes were characteristic of a single cubic phase in which lattice parameter decrease with lithium extraction for all compositions.