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.

A positive electrode active material has an inner core and a shell coating the inner core, wherein the inner core comprises at least one of a ternary material, dLi.sub.2MnO.sub.3.Math.(1?d)LiMO.sub.2 and LiMPO.sub.4, where 0<d<1, and M includes one or more selected from Fe, Ni, Co, and Mn; and the shell contains a crystalline inorganic substance having a full width at half maximum of the main peak of 0-3? as measured by means of X-ray diffraction, and the crystalline inorganic substance includes one or more selected from a metal oxide and an inorganic salt.

Devices are provided, which in embodiments, comprise a source configured to generate oxygen ions via a redox reaction; and an oxygen ion transport material through which oxygen ions generated from the source are transported. The oxygen ion transport material may have either: Formula I A.sup.x+B.sub.2.sup.y+C.sub.4.sup.z+O.sub.12 .sup.2? wherein x+2y+4z=24 and (x, y, z) is (4, 2, 4), (x, y, z) is (2, 1, 5), or (x, y, z) is (3, 2.5, 4); Formula II A.sub.4.sup.x+B.sub.5.sup.y+C.sub.4.sup.z+O.sub.22.sup.2? wherein 4x+5y+4z=44 and (x, y, z) is (2, 4, 4) or (x, y, z) is (3, 3.2, 4) or (x, y, z) is (2.5, 3.6, 4); or Formula III Bi.sub.2MO.sub.4X; wherein A, B, and C are independently selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, lanthanoids, P, Th, and combinations thereof, and wherein M is selected from rare earth elements and combinations thereof and X is selected from halogens and combinations thereof. Methods of using the devices are also provided, which in embodiments, which comprise transporting oxygen ions generated from the source through the oxygen ion transport material.

Exemplary layered double hydroxides (LDHs) may comprise a compound of formula Mg.sub.4-yAlX.sub.y(OH).sub.2, wherein X is Mn.sup.+2, Cu.sup.+2, Zn.sup.+2, or Fe.sup.+2, and 0.01?y?1. Exemplary layered double hydroxide hydrogels (LDH-gels) may comprise a hydrogel and at least one LDH. Exemplary hydrogels may comprise polyethylene (glycol) diacrylate (PEGDA) or polyacrylamide (PAAm). Exemplary LDH-gels may comprise at least one LDH comprising a compound of formula Mg.sub.4-yAlX.sub.y(OH).sub.2, wherein X is Mn.sup.+2, Cu.sup.+2, Zn.sup.+2, or Fe.sup.+2, and 0.01?y?1.

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.

The invention relates to electrodes that contain active materials of the formula: A.sub.aM.sub.bX.sub.xO.sub.y wherein A is one or more alkali metals selected from lithium, sodium and potassium; M is selected from one or more transition metals and/or one or more non-transition metals and/or one or more metalloids; X comprises one or more atoms selected from niobium, antimony, tellurium, tantalum, bismuth and selenium; and further wherein 0<a6; b is in the range: 0<b4; x is in the range 0<x1 and y is in the range 2y10. Such electrodes are useful in, for example, sodium and/or lithium ion battery applications.

A composition used for forming a PZT-based piezoelectric film formed of Mn and Nb co-doped composite metal oxides is provided, in which the composition includes PZT-based precursors so that a metal atom ratio (Pb:Mn:Nb:Zr:Ti) in the composition satisfies (1.00 to 1.25):(0.002 to 0.056):(0.002 to 0.056):(0.40 to 0.60):(0.40 to 0.60), a rate of Mn is from 0.20 to 0.80 when the total of metal atom rates of Mn and Nb is 1, a rate of Zr is from 0.40 to 0.60 when the total of metal atom rates of Zr and Ti is 1, and the total rate of Zr and Ti is from 0.9300 to 0.9902 when the total of metal atom rates of Mn, Nb, Zr, and Ti is 1.

A compound containing Sn, Te and Mn, and further containing either one or both of Sb and Bi.

Provided are a positive electrode active material and a preparation method thereof, a positive electrode plate, a secondary battery, a battery module, a battery pack, and an electric apparatus. The positive electrode active material includes a core including Li.sub.1+xM.sub.n1?yA.sub.yP.sub.1?z,R.sub.zO.sub.4, a first coating layer enveloping the core and containing a crystalline pyrophosphate Li.sub.aMP.sub.2O.sub.7 and/or Mb(P.sub.2O.sub.7).sub.e, a second coating layer enveloping the first coating layer and containing a crystalline oxide M.sub.dO.sub.e, and a third coating layer enveloping the second coating layer and containing carbon. The positive electrode active material of this application can reduce Li/Mn anti-site defects generated, reduce dissolving-out amount of manganese, lower the lattice change rate, increase the capacity of the secondary battery, and improve the cycling performance, high-temperature storage performance, and safety performance of the secondary battery.

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.