Embodiments of the present invention relate to a cathode active material, a method for manufacturing the same, and a lithium secondary battery including the same.

According to an embodiment, a cathode active material can be provided, the cathode active material comprising: a lithium metal oxide including a core and a shell disposed on a surface of the core; and a coating layer disposed on a surface of the lithium metal oxide, wherein a c value that satisfies Equation 1 and is in a range of 0.3 to 0.7, and the core and the shell have a layered crystalline structure.

c=b/a  [Equation 1]

(in Equation 1, a is a peak at 530 to 533 eV and b is a peak at 528 to 531 eV in an XPS spectrum of the coating layer)

Provided are a positive electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the same.

According to an exemplary embodiment, a positive electrode active material for a lithium secondary battery which includes lithium metal oxide particles and a coating layer placed on at least a part of a surface of the lithium metal oxide particles may be provided, wherein the coating layer includes B, LiOH, Li.sub.2CO.sub.3, and Li.sub.2SO.sub.4.

A lithium ion battery according to the present invention comprises a positive electrode, a negative electrode, a positive electrode lead that is connected to the positive electrode, an insulation tape that covers the positive electrode lead, and an electrolyte solution. The insulation tape comprises a base material layer that is mainly composed of an organic material, and a filler layer that is provided on the base material layer; the filler layer contains an oxide compound of an alkaline earth metal; and the electrolyte solution contains fluorine.

An object is to provide an electrode active material that can provide an alkali metal battery having a longer charge/discharge life and a higher capacity. The problem is solved by means of an electrode active material for an alkali metal battery, represented by formula: A.sub.a1MS.sub.a2X.sub.a3 wherein A is selected from Li and Na; M is selected from V, Nb, Ta, Ti, Zr, Hf, Cr, Mo, and W which are group 4 to 6 elements; X is selected from F, Cl, Br, I, CO.sub.3, SO.sub.4, NO.sub.3, BH.sub.4, BF.sub.4, PF.sub.6, ClO.sub.4, CF.sub.3SO.sub.3, (CF.sub.3SO.sub.2).sub.2N, (C.sub.2F.sub.5SO.sub.2).sub.2N, (FSO.sub.2).sub.2N, and [B(C.sub.2O.sub.4).sub.2]; a1 is 1 to 9; a2 is 2 to 6; when a3 is 3 and a3 is 0, a2 is not 4; and when M does not include V, a3>0.

The present exemplary embodiments relate to a positive electrode active material and a lithium secondary battery including the same. The positive active material for a lithium secondary battery according to an exemplary embodiment includes lithium metal oxide particles including lithium, nickel, cobalt, manganese and doping elements, and includes a first domain and a second domain inside the lithium metal oxide particles.

A secondary battery with favorable cycle performance is provided. Alternatively, a secondary battery with higher capacity is provided. A positive electrode active material layer including a first graphene layer, a second graphene layer, and a positive electrode active material. The first graphene layer includes a first region covering the positive electrode active material. The second graphene layer includes a second region covering the positive electrode active material and a third region overlapping with the first region. The first region includes a plane positioned between the positive electrode active material and the third region and formed of arranged six-membered carbon rings. The positive electrode active material includes a fourth region with a layered rock-salt structure. A lithium layer with a layered rock-salt structure included in the fourth region is substantially perpendicular to the plane formed of six-membered carbon rings and included in the second region.

The present exemplary embodiments relate to a positive electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same. A positive active material for a lithium secondary battery according to an exemplary embodiment is a lithium metal oxide particle in the form of secondary particles including a plurality of primary particles: a first coating layer positioned on at least a part of the surface of the primary particle, and a second coating layer positioned over at least a portion of the secondary particle surface, the first coating layer comprising a first niobium compound, the second coating layer comprising the first niobium compound and a second niobium compound having a composition different from the first niobium compound.

This positive electrode active material for a non-aqueous electrolyte secondary battery contains a lithium-transition metal composite compound. The lithium-transition metal composite compound is represented by general formula Li.sub.xMn.sub.yNi.sub.zMe.sub.αO.sub.aF.sub.b (in the formula, 1≤x≤1.2, 0.4≤y≤0.8; 0≤z≤0.4, x+y+z=2, 0<α<0.05, 1.8≤a≤2, and 1.8≤a±b≤2.2 are satisfied, and Me represents at least two kinds of elements selected from metal elements other than Li, Mn, and Ni) and Me includes at least one kind of element having an ion radius of 0.6 Å or more.

A positive electrode active material for an all-solid-state lithium ion secondary battery, containing: a lithium-metal composite oxide particle having a niobium solid solution layer and a center other than the niobium solid solution layer; and a coating layer coating at least a part of a surface of the lithium-metal composite oxide particle and formed of a compound containing lithium and niobium, an average thickness of the coating layer is 2 nm or more and 1 μm or less, and an average thickness of the niobium solid solution layer is 0.5 nm or more and 20 nm or less.

An electrochemical device, including a positive electrode. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer includes particles A and particles B. A circularity of a particle A is R.sub.A, a cross-sectional area of the particle A is S.sub.A, a circularity of a particle B is R.sub.B, a cross-sectional area of the particle B is S.sub.B, where R.sub.B<0.4≤R.sub.A and S.sub.B<20 μm.sup.2≤S.sub.A. Based on a total area of a cross section of the positive electrode in a direction perpendicular to the positive current collector, a ratio of a total area percent of the particles A to a total area percent of the particles B is 1:9 to 8:2. The electrochemical device exhibits excellent electrochemical performance, especially reduces the amount of generated gas and improves cycle stability of the electrochemical device.