An electrode includes a material represented by Li.sub.1-xM.sub.xCoO.sub.2-d where 0<x≤0.2 and 0≤d≤0.2. The variable M includes a metal selected from the group consisting of transition metals, Group I elements, and Group II elements.

Mixed-metal oxides and lithiated mixed-metal oxides are disclosed that involve compounds according to, respectively, Ni.sub.xMn.sub.yCo.sub.zMe.sub.αO.sub.β and Li.sub.1+γNi.sub.xMn.sub.yCo.sub.zMe.sub.αO.sub.β. 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; 0≤x≤1; 0≤y≤1; 0≤z<1; x+y+z>0; 0≤α≤0.5; and x+y+α>0. For the mixed-metal oxides, 1≤β≤5. For the lithiated mixed-metal oxides, −0.1≤γ≤1.0 and 1.9≤β≤3. 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.

Oxygen electrodes are provided, comprising a perovskite compound having Formula (I), Sr(Ti.sub.1-xFe.sub.x-yCo.sub.y)O.sub.3-δwherein 0.90≥x≥0.40 and 0.02≥y≥0.30. Electrochemical devices comprising such oxygen electrodes are also provided, comprising a counter electrode in electrical communication with the oxygen electrode, and a solid oxide electrolyte between the oxygen electrode and the counter electrode. Methods of using such electrochemical devices are also provided, comprising exposing the oxygen electrode to a fluid comprising O.sub.2 under conditions to induce the reaction O.sub.2+4e.sup.−.fwdarw.2O.sup.2−, or to a fluid comprising O.sup.2− under conditions to induce the reaction 2O.sup.2−.fwdarw.O.sub.2+4e.sup.−.

In an aspect, a Co.sub.2Z ferrite has the formula: (Ba.sub.1−xSr.sub.x).sub.3Co.sub.2+yM.sub.yFe.sub.24−2y−zO.sub.41. M is at least one of Mo, Ir, or Ru. The variable x can be 0 to 0.8, or 0.1 to 0.8. The variable y can be 0 to 0.8, or 0.01 to 0.8. The variable z can be −2 to 2. The Co.sub.2Z ferrite can have an average grain size of 5 to 100 nanometers, or 30 to 80, or 10 to 40 nanometers as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction.

A lithium cobalt-based positive electrode active material is provide, which includes sodium and calcium, wherein the total amount of the sodium and calcium is 150 ppm to 500 ppm based on the total weight of the lithium cobalt-based positive electrode active material. A method for preparing the lithium cobalt-based positive electrode active material is also provided.

In one embodiment, the present disclosure relates to a positive electrode active material in which a lithium cobalt oxide is doped with a doping element including a metallic element and a halide element, wherein the positive electrode active material is represented by Formula 1 and satisfies Equation 1, and a positive electrode for a lithium secondary battery and a lithium secondary battery, either of which include the positive electrode active material:
Li(Co.sub.1-x-y-zM.sup.1.sub.xM.sup.2.sub.yM.sup.3.sub.z)O.sub.2-aH.sub.a  [Formula 1]
(2x+3y+4z−a)/(x+y+z+a)<2.5.  [Equation 1]

Disclosed herein are doped thermoelectric ceramic oxide compositions comprising a calcium cobaltite ceramic. The doped thermoelectric ceramic oxide compositions can have a formula Ca.sub.3-xM.sup.2.sub.xCo.sub.4O.sub.9M.sup.1.sub.y, where M.sup.1 represents a first metal dopant, M.sup.2 represents a second metal dopant, x is a number having a value of from about 0.00 to about 3.00, and y is a number having a value of from about 0.01 to about 0.50. The doped thermoelectric ceramic oxide compositions have an increased energy conversion efficiency as compared to an undoped or conventional thermoelectric ceramic oxide materials. Also disclosed are methods for making the doped thermoelectric ceramic oxide compositions. Products and devices are disclosed comprising the thermoelectric ceramic oxide compositions, e.g., solid-state conversion devices that can utilize heat to generate electricity. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

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.

Provided is a cobalt precursor for preparing a lithium cobalt oxide of a layered structure which is included in a positive electrode active material, wherein the cobalt precursor is cobalt oxyhydroxide (CoMOOH) doped with, as dopants, magnesium (Mg) and M different from the magnesium.

The present invention relates to a metal oxide powder, a method of preparing the same, and a lithium secondary battery using the same, which comprises: a metal oxide powder is represented by Formula (1),
Li.sub.x(M.sub.1-m-zA.sub.mD.sub.z)O.sub.tFormula (1) in the above Formula (1), 0.85x1.2, 0m0.01, 0<z0.04, 1.85t2.2, M is selected from the group consisting of Ni, Co, Mn and combinations thereof, A is selected from the group consisting of Mg, Ca, Sr, Ba and combinations thereof, D is selected from the group consisting of Ti, Zr, Ce, Ge, Sn and combinations thereof, and E is an average oxidation number of A and D, and E>3.5.