A mixed conductor represented by Formula 1:
A.sub.4±xTi.sub.5−yG.sub.zO.sub.12−δ  Formula 1 wherein, in Formula 1, A is a monovalent cation, G is at least one of a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, or a hexavalent cation, with the proviso that G is not Ti or Cr, wherein 0<x<2, 0.3<y<5, 0<z<5, and 0<δ≤3.

A mixed conductor represented by Formula 1:

A.sub.xTi.sub.5yG.sub.zO.sub.12Formula 1 wherein, in Formula 1, A is a monovalent cation, G is at least one of a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, or a hexavalent cation, with the proviso that G is not Ti or Cr, wherein 0<x<2, 0.3<y<5, 0<z<5, and 0<3.

In at least one embodiment, a rechargeable battery is provided comprising an anode having an active material including MSb.sub.2O.sub.4 having a purity level of greater than 93 percent by weight, wherein M is a metal. The metal may have an oxidation state of 2+ and may include transition metals and/or alkali-earth metals. The anode active material may be synthesized using metal acetates or metal oxides. The synthesis may include heating at a first temperature to remove oxygen and water and reacting at a second temperature to form the MSb.sub.2O.sub.4 structure, which may be a spinel crystal structure.