Abstract: The present invention generally relates to certain oxide materials having relatively high energy and/or power densities. Various aspects of the invention are directed to oxide materials having a structure Bi(MjYk)O2, for example, a structure Lij(NijYk)O2 such as Li(Nio.5Mn0.5)02. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some cases, Y may have a combined valency of at least about 4. In some embodiments, such an oxide material may have an 03 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising while another set of atomic planes comprises Ni and/or Y.