Electrodes comprising mixed active particles

1. A battery, comprising:

a first electrode comprising two or more groups of particles having differing chemical compositions, wherein each group of particles comprises a material independently selected from the group consisting of:

(a) materials of the formula A 1 a M 1 b (XY 4 ) c Z d ;

(b) materials of the formula A 2 e M 2 f O g ; and

(c) materials of the formula A 3 h Mn i O 4 ;

wherein

(i) A 1 , A 2 , and A 3 are independently selected from the group consisting of Li, Na, K, and mixtures thereof, and 0<a≦8, 0<e≦6;

(ii) M 1 is one or more metals, comprising at least one metal which is capable of undergoing oxidation to a higher valence state, and 0.8≦b≦3;

(iii) M 2 is one or more metals, comprising at least one metal selected from the group consisting of Fe, Co, Ni, Mo, V, Zr, Ti, Mo, and Cr, and 1≦f≦6;

(iv) XY 4 is selected from the group consisting of X′O 4−x Y′ x , X′O 4−y Y′ 2y , X″S 4 , and mixtures thereof, where X′ is selected from the group consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof; X″ is selected from the group consisting of P, As, Sb, Si, Ge, V and mixtures thereof; Y′ is halogen; 0≦x<3; and 0<y<2; and 0<c≦3;

(v) Z is OH, a halogen, or mixtures thereof, and 0≦d≦6; and

(vi) 0<g≦15; and

(vii) M 1 , M 2 , X, Y, Z, a, b, c, d, e, f, g, h, i, x and y are selected so as to maintain electroneutrality of each material;

(b) the battery further comprising a second electrode which is a counter-electrode to the first electrode; and

(c) an electrolyte,

wherein the two or more groups of particles having differing chemical compositions comprises a first group of particles and a second group of particles, wherein:

(a) the first group of particles comprises an inner and an outer region, wherein the inner region comprises a cubic spinel manganese oxide, and the outer region comprises a manganese oxide that is enriched in Mn +4 relative to the inner region, and

(b) the second group of particles comprises a material selected from materials of the formula A 1 a M 1 b (XY 4 ) c Z d ; materials of the formula A 2 e M 3 f O g ; and mixtures thereof.

2. The battery of claim 1 , comprising a material of the formula A 1 a M 1 b (XY 4 ) c Z d .

3. The battery of claim 1 , comprising a material of the formula A 1 a M 1 b XY 4 Z d .

4. The battery of claim 1 , comprising a material of the formula A 1 a M 1 b (XY 4 ) 3 Z d .