US Patent 7087346 Alkali/transition metal phosphates and related electrode active materials

Electrode active materials comprising lithium or other alkali metals, a transition metal, and a phosphate or similar moiety, of the formula:Aa+xMbP1−xSixO4wherein(a) A is selected from the group consisting of Li, Na, K, and mixtures thereof, and 0<a<1.0 and 0≦x≦1;(b) M comprises one or more metals, comprising at least one metal which is capable of undergoing oxidation to a higher valence state, where 0<b≦2; andwherein M, a, b, and x are selected so as to maintain electroneutrality of said compound.