Mixed-metal oxides and lithiated mixed-metal oxides are disclosed that involve compounds according to, respectively, Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub. and Li.sub.i+Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub.. In these compounds, Me is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, and combinations thereof; 0x1; 0y1; 0z<1; x+y+z>0; 00.5; and x+y+>0. For the mixed-metal oxides, 15. For the lithiated mixed-metal oxides, 0.11.0 and 1.93. The mixed-metal oxides and the lithiated mixed-metal oxides include particles having an average density greater than or equal to 90% of an ideal crystalline density.

A layered lithium metal oxide powder for a cathode material used in a rechargeable battery, with the general formula (1x)[Li.sub.a-bA.sub.b].sub.3a[CO.sub.1-cM.sub.c].sub.3b[O.sub.2-d-eN.sub.e].sub.6c.xLi.sub.3PO.sub.4, with 0.0001x0.05, 0.90a1.10, 0<b+c0.1, 0.1d0.1 and e0.05, wherein A and M are one or more elements including at least one of the group consisting of Mg, Ti and Al; wherein N is either one or more dopants of the group consisting of F, S, N and P; the powder consisting of a core and an ion-conductive electron-insulating surface layer, the core having a layered crystal structure and the surface layer comprising a mixture of elements of the core material, oxides comprising either one or more elements of the group consisting of Mg, Ti and Al; and Li.sub.3PO.sub.4.

An oxygen evolution catalyst of the formula: Sr.sub.2MCoO.sub.5 where M=Al, Ga wherein M is bonded with four oxygen atoms to form a tetrahedron. The catalyst is operated at a potential of less than 1.58 volts vs. RHE at a current density of 50 A/cm.sup.2 for a pH of 7-13. The catalyst is operated at a potential of less than 1.55 volts vs. RHE at a current density of 50 A/cm.sup.2 and a pH of 13. The oxygen evolution catalyst of the formula: Sr.sub.2GaCoO.sub.5 wherein the catalyst is operated at a potential of less than 1.53 volts vs. RHE at a current density of 50 A/cm.sup.2 and a pH of 7. The oxygen evolution catalyst of formula: Sr.sub.2GaCoO.sub.5 wherein the catalyst maintains a current within 94% after 300 minutes at a potential of 1.645 volts vs. RHE wherein the current is greater than 1 milliamp and a pH of 7.

An electrode formed from a material represented by Li.sub.1xM.sub.xCo.sub.1yM.sub.yO.sub.2d where 0<x0.2, 0y<1, and 0<d0.2. M and M each independently comprises a metal selected from the group consisting of transition metals, Group I elements, and Group II elements.

A magnetoelectric effect material includes as a primary component, a polycrystalline oxide ceramic containing at least Sr, Co, and Fe. In the polycrystalline oxide ceramic, the crystal c-axis is oriented in a predetermined direction, and the degree of orientation of the c-axis is 0.2 or more by a Lotgering method. A component substrate is formed of this magnetoelectric effect material.

Mixed-metal oxides and lithiated mixed-metal oxides are disclosed that involve compounds according to, respectively, Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub. and Li.sub.1+Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub.. In these compounds, Me is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, and combinations thereof; 0x1; 0y1; 0z<1; x+y+z>0; 00.5; and x+y+>0. For the mixed-metal oxides, 15. For the lithiated mixed-metal oxides, 0.11.0 and 1.93. The mixed-metal oxides and the lithiated mixed-metal oxides include particles having an average density greater than or equal to 90% of an ideal crystalline density.

Mixed-metal oxides and lithiated mixed-metal oxides are disclosed that involve compounds according to, respectively, Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub. and Li.sub.i+Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub.. In these compounds, Me is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, and combinations thereof; 0x1; 0y1; 0z1; x+y+z>0; 00.5; and x+y+>0. For the mixed-metal oxides, 15. For the lithiated mixed-metal oxides, 0.11.0 and 1.93. The mixed-metal oxides and the lithiated mixed-metal oxides include particles having an average density greater than or equal to 90% of an ideal crystalline density.

There is provided a thermoelectric conversion material which is characterized by being composed of a sintered body of plate-like crystals of a composite oxide represented by general formula (2) Bi.sub.fCa.sub.gM.sup.3.sub.hCo.sub.iM.sup.4.sub.jO.sub.k, and by having a density of 4.0-5.1 g/cm.sup.3. This thermoelectric conversion material is also characterized in that: when observed by SEM, the ratio of the plate-like crystals of a composite oxide represented by general formula (2) having an inclination in the major axis direction within 020 relative to the surface of the thermoelectric conversion material is 60% or more on the number basis; the average length of the lengths of the plate-like crystals of a composite oxide represented by general formula (2) is 20 m or more; and the aspect ratio of the plate-like crystals of a composite oxide represented by general formula (2) is 20 or more.

A positive active material, a positive electrode, and a lithium secondary battery, the positive active material including a lithium cobalt oxide compound, wherein the lithium cobalt oxide compound includes magnesium in a range of about 0.1 mol % to about 2 mol %, based on a total number of moles of transition metals in the lithium cobalt oxide compound, and a thickness of a lithium layer in the lithium cobalt oxide compound is in a range of about 2.62 to about 2.65 .

The present invention relates to positive electrode active material particles and a secondary battery including the same and provides positive electrode active material particles comprising: a core including a first lithium transition metal oxide; and a shell surrounding the core, wherein the shell has a form in which metal oxide particles are embedded in a second lithium transition metal oxide, and at least a part of the metal oxide particles is present by being exposed at a surface of the shell. The positive electrode active material particles according to the present invention prevent a transition metal and an electrolyte from causing a side reaction by exposing a part of a metal oxide, having low reactivity, at a surface of the active materials, thereby improving safety and lifespan. As the electrical conductivity of the active materials becomes lower, excellent stability can be maintained even at high temperature and in battery-breakdown situations.