| abstract |
The invention provides an electrochemical cell which includes a first electrode and a second electrode which is a counter electrode to said first electrode, and an electrolyte material interposed there between. The first electrode comprises an electrode active material represented by the general nominal formula A<SUB>a</SUB>[M<SUB>m</SUB>,MI<SUB>n</SUB>,MII<SUB>o</SUB>](XY<SUB>4</SUB>)<SUB>d</SUB>Z<SUB>e</SUB>, wherein at least one of M, MI and MII is a redox active element, 0<m,n,o<=4, and ½[V(MI)+V(MII)]=V(M), wherein V(M) is the valence state of M, V(MI) is the valence state of MI, and V(MII) is the valence state of MII. |