The present invention discloses a method for preparing lithium-rich manganese-based cathode material. The method comprises: dispersing -MnO.sub.2 micron particles, a nickel salt and a lithium-containing compound in a solvent to obtain a mixture, then evaporating the mixture to remove the solvent, and calcining the solid product obtained from the evaporation; wherein the lithium-containing compound is a lithium salt and/or lithium hydroxide. The present invention also provides a lithium-rich manganese-based cathode material prepared by the above method. The present invention also provides a lithium-ion battery of which anode material contains the foregoing lithium-rich manganese-based anode material. The lithium-rich manganese-based cathode material provided by the present invention has high rate capability and prolonged cycle stability.

The present application provides a positive electrode and a lithium-ion battery. The positive electrode comprises a current collector; a first active material layer comprising a first active material; and a second active material layer; wherein the first active material layer is arranged between the current collector and the second active material layer, the first active material layer comprises a first active material, and the first active material is at least one selected from a group consisting of a modified lithium transition metal oxide positive electrode material and a modified lithium iron phosphate. The positive electrode of the present application helps to improve the thermal stability of the lithium-ion battery, and the improvement of the thermal stability may reduce the proportion of the thermal runaway when the lithium-ion battery is internally short-circuited so that the safety performance of the lithium-ion battery is improved.

Disclosed are a precursor for preparation of a lithium composite transition metal oxide, a method for preparing the same and a lithium composite transition metal oxide obtained from the same. More particularly, the transition metal precursor which has a composition represented by Formula 1 below and is prepared in an aqueous transition metal solution, mixed with a transition metal-containing salt, including an alkaline material, the method for preparing the same and the lithium composite transition metal oxide obtained from the same are disclosed.

Mn.sub.aM.sub.b(OH.sub.1-x).sub.2-yA.sub.y (1) wherein M is at least one selected form the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals; A is at least one selected form the group consisting of anions of PO.sub.4, BO.sub.3, CO.sub.3, F and NO.sub.3, and 0.5a1.0; 0b0.5; a+b=1; 0<x<1.0; and 0y0.02.

Disclosed are a precursor for preparation of a lithium composite transition metal oxide, a method for preparing the same and a lithium composite transition metal oxide obtained from the same. More particularly, the transition metal precursor which has a composition represented by Formula 1 below and is prepared in an aqueous transition metal solution, mixed with a transition metal-containing salt, including an alkaline material, the method for preparing the same and the lithium composite transition metal oxide obtained from the same are disclosed.
Mn.sub.aM.sub.b(OH.sub.1-x).sub.2-yA.sub.y(1) wherein M is at least one selected form the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals; A is at least one selected form the group consisting of anions of PO.sub.4, BO.sub.3, CO.sub.3, F and NO.sub.3, and 0.5a1.0; 0b0.5; a+b=1; 0<x<1.0; and 0y0.02.

A perovskite material represented by Formula 1:
Li.sub.xA.sub.yM.sub.zO.sub.3-?Formula 1 wherein in Formula 1, 0<x?1, 0<y?1, 0<x+y<1, 0<z?1.5, 0???1, A is H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, or a combination thereof, and M is Ni, Pd, Pb, Fe, Ir, Co, Rh, Mn, Cr, Ru, Re, Sn, V, Ge, W, Zr, Mo, Hf, U, Nb, Th, Ta, Bi, Li, H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Mg, Al, Si, Sc, Zn, Ga, Ag, Cd, In, Sb, Pt, Au, or a combination thereof.

The present invention relates to a cathode active material for a secondary battery and a preparation method thereof, and more particularly, to a lithium composite oxide including a secondary particle formed as primary particles cohere, in which a manganese (Mn) oxide is present in the periphery of the primary particles, a concentration of an Mn oxide in the primary particle has a concentration gradient from the center of the primary particle to a surface of the particle, a concentration of an Mn oxide in the secondary particle has a concentration gradient from a surface of the secondary particle to the center thereof, and a lithium ion migration path is formed in the primary particle, and a preparation method thereof. A secondary battery including the cathode active material for a secondary battery may have high safety, while exhibiting high capacity and high output.

A composite positive active material includes: a composite including a first metal oxide represented by Formula 1 and having a layered structure, and a second metal oxide having at least one crystal structure selected from a layer structure, a perovskite structure, a rock salt structure, and a spinel structure, wherein a content of the second metal oxide is greater than 0 and equal to or less than 0.2 moles, per mole of the composite,
LiNi.sub.xM.sup.1.sub.1-xO.sub.2-eM.sup.2.sub.eFormula 1
wherein, in Formula 1, M.sup.1 is at least one element selected from Group 4 to Group 14 of the Periodic Table of the Elements; M.sup.a is at least one element selected from F, S, Cl, and Br; 0.7?x<1; and 0?e<1. Also, a positive electrode including the composite positive active material, and a lithium battery including the positive electrode.

A method of forming a high energy density composite cathode material is disclosed. The method includes providing a lithium-rich manganese layered oxide (LRMO), coating the LRMO with a TiO.sub.2 precursor, and ball-milling the TiO.sub.2 coated LRMO with LiH to form a Li.sub.xTiO.sub.2 coated LRMO composite, wherein x is less than or equal to 1 and greater than zero.

A positive active material includes an overlithiated lithium transition metal oxide including: a metal cation and a Li.sub.2MO.sub.3 phase, wherein M is at least one metal selected from a Period 4 transition metal having an average oxidation number of +4 and a Period 5 transition metal having an average oxidation number of +4, and wherein an amount of the Li.sub.2MO.sub.3 phase is less than or equal to about 20 mole percent, based on 1 mole of the overlithiated lithium transition metal oxide.

A transition metal oxide containing solid-solution lithium that realizes high initial discharge capacity and capacity retention is represented by the compositional formula: Li.sub.1.5[Ni.sub.aM.sub.bMn.sub.c[Li].sub.d]O.sub.3, wherein M represents at least one kind of element selected from the group consisting of silicon, phosphorus and metal elements (excluding Ni, Mn and Li), a, b, c and d satisfy specific relationships, and n is the valence of M. The oxide has a layered structure site and a site which changes to a spinel structure by performing a charge or a charge-discharge in a predetermined electric potential range, and a spinel structure change ratio k in a range of 0.25k<1.0 when the spinel structure change ratio is assumed to be 1 in a case where Li.sub.2MnO.sub.3 of the layered structure in the transition metal oxide containing solid-solution lithium completely changes to LiMn.sub.2O.sub.4 of the spinel structure.