LiCu{sub x}{sup 2}Cu{sub y}{sup 3}Mn{sub [2{minus}(x+y)]}{sup 3,4}O{sub 4}: 5 V cathode materials

A series of LiCu{sub x}{sup 2}Cu{sub y}{sup 3}Mn{sub [2{minus}(x+y)]}{sup 3,4}O{sub 4} spinels was prepared by solid-state methods. Powder x-ray diffraction analysis proved that the LiCu{sub x}{sup 2}Cu{sub y}{sup 3}Mn{sub [2{minus}(x+y)]}{sup 3,4}O{sub 4} family assumes cubic spinel structures with a unit cell parameter slightly smaller than that of LiMn{sub 2}O{sub 4}. Cyclic voltammetry and chronopotentiostatic techniques revealed that these materials exhibited two discharge regimes, at 4.1 and 4.9 V vs. the Li/Li{sup +} couple. The discharge capacity of LiCu{sub x}{sup 2}Cu{sub y}{sup 3}Mn{sub [2{minus}(x+y)]}{sup 3,4}O{sub 4} was 71 mAh/g (97% of theoretical), with surprisingly good stability on cycling.