Mixed oxide containing a lithium manganese spinel and process for its preparation

1. Mixed oxide containing

a) a mixed-substituted lithium manganese spinel as a first constituent in which a first portion of the manganese lattice sites are occupied by lithium ions and

b) a boron-oxygen constituent as a second constituent,

wherein the mixed oxide is a single-phase homeotype mixed crystal comprising the two constituents wherein the second constituent is in the same phase as the first Constituent, and

wherein the mixed oxide has a composition satisfied by the following formula:

[(Li 1−a M a )(Mn 2−c−d Li c N d )O x ].b(B z O y H u X v )

 wherein

0≦a<0.1;

d ≦1.2

3.5<×<4.5;

0.01<c<0.06

z=1, 2 or 4

y=1, 2, 3 or 7

u=0, 1, 2 or 3

v=0, 1, 2 or 3

0.01<b<0.5

M is at least one element selected from the group of Zn, Mg, and Cu;

N is at least on element selected from the group of Al, Mg, Zn, Co, Ni, Cu and Cr; and

X is at least one element selected from the group Li, Na, K,

wherein in the mixed-substituted lithium manganese spinal, and second portion of the manganese lattice sites are occupied by mental ions of N selected from at least one of Ni and Co, wherein either “d” of Ni is 0.5+/−0.1 or “d”of Co is 1+/−0.2, and the size of the primary crystallites of the mixed oxide, measured as D 50 , is at least 0.5 μm.

2. Mixed oxide according to claim 1 , wherein in the mixed-substituted lithium manganese spinel further manganese lattice sites are occupied by metal ions of N selected from the group consisting of Al, Mg, Zn, Cu and Cr.

3. Mixed oxide according to claim 2 , wherein some of the lithium ions on the 8a tetrahedral sites are substituted by the metal ion M, selected from the group consisting of Zn, Mg and Cu.

4. Mixed oxide according to claim 1 , wherein the X-ray diffractogram of the mixed oxide has a signal at a diffraction angle 2θ in the range from 63.5 to 65°, in which the ratio of the line widths B 10 measured at 10% of the signal height to the line width B 50 measured at 50% of the signal height is less than 2.0, preferably less than 1.8.

5. Mixed oxide according to claim 4 with a BET surface area of less than 4 m 2 /g.

6. Mixed oxide according to claim 5 , wherein the size of the primary crystallites of the mixed oxide, measured as D 50 , is greater than 1 μm.

7. An electrode, comprising an electrically conductive support to which a mixed oxide according to claim 1 is applied.

8. Secondary battery with an electrode according to claim 7 .