Active electrode material

A method of making a mixed niobium oxide, the method comprising steps of:

• providing one or more precursor materials;
• mixing said precursor materials to form a precursor material mixture;
• and
• heat treating the precursor material mixture in a temperature range from 400° C.-1350° C., thereby providing the mixed niobium oxide;
• wherein the mixed niobium oxide has the composition M1aM22-aM3bNb34-bO87-c-dOd, wherein:
• M1 and M2 are different;
• M1 is selected from Mg, Ca, Sr, Y, La, Ce, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi and mixtures thereof;
• M2 is Zn or Cu;
• M3 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof;
• Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof;
• 0≤a<1.0;0≤b≤3.4;−0.5≤c≤4.35;0≤d≤4.35;
• one or more of a, b, c, and d does not equal 0;
• and
• when a, b, and d equal zero, c is greater than zero;
• wherein a crystal structure of the mixed niobium oxide as determined by X-ray diffraction corresponds to the crystal structure of one or more of Zn2Nb34O87 and Cu2Nb34O87.