Positive electrode active material for secondary battery, and secondary battery including the same

Patent metadata

Field	Value
Publication number	US-2018294477-A1
Application number	US-201615574071-A
Country	US
Kind code	A1
Filing date	Nov 30, 2016
Priority date	Nov 30, 2015
Publication date	Oct 11, 2018
Grant date	—

Abstract

(in formulae 1 to 3, A, M1 to M5, a, x, y, z, w, m, n, p, and q are the same as those defined in the specification).

First claim

1 . A positive electrode active material for a secondary battery, the positive electrode active material comprising:
a core comprising a lithium composite metal oxide of Formula 1 below; a first surface-treated layer positioned on a surface of the core, and including a lithium oxide of Formula 2 below; and a second surface-treated layer positioned on the core or the first surface-treated layer, and including a lithium compound of Formula 3 below,
Li a Ni 1-x-y Co x M1 y M3 z M2 w O 2   [Formula 1]

(in Formula 1, M1 is at least any one selected from the group consisting of Al and Mn, M2 is any one or at least two elements selected from the group consisting of Zr, Ti, Mg, Ta and Nb, and M3 is any one or at least two elements selected from consisting of W, Mo, and Cr, and 1.0≤a≤1.5, 0<x≤0.5, 0<y≤0.5, 0.002≤z≤0.03, 0≤w≤0.02, 0<x+y≤0.7),
Li m M4O (m+n)/2   [Formula 2]

(in Formula 2, M4 is any one or at least two elements selected from the group consisting of W, Mo, and Cr, and 2≤m≤6, and n is an oxidation number of M4),
Li p M5 q A r   [Formula 3]

(in Formula 3, M5 is any one or at least two elements selected from the group consisting of elements in Group 13 to Group 15, A is any one selected from the group consisting of O, OH, CO 3 , PO 4 , F, and SO 4 , and 1≤p≤10, 1≤q≤10, r=(p+s)/t where s is the absolute value of an oxidation number of M5 and t is the absolute value of an oxidation number of A).

2 . The positive electrode active material for a secondary battery of claim 1 , wherein M4 in Formula 2 comprises at least any one among W and Cr.

3 . The positive electrode active material for a secondary battery of claim 1 , wherein the lithium oxide of Formula 2 comprises any one selected from the group consisting of Li 2 WO 4 , Li 4 WO 5 , and Li 6 WO 6 , or a mixture of at least two thereof.

4 . The positive electrode active material for a secondary battery of claim 1 , wherein the first surface-treated layer is formed to have a surface area of 25% or more to less than 100% with respect to an entire surface area of the core.

5 . The positive electrode active material for a secondary battery of claim 1 , wherein the first surface-treated layer has an average thickness ratio of 0.001 to 0.1 with respect to a radius of the core.

6 . The positive electrode active material for a secondary battery of claim 1 , wherein A in Formula 3 is any one selected from the group consisting of O, PO 4 , and F.

7 . The positive electrode active material for a secondary battery of claim 1 , wherein M5 in Formula 3 is any one or at least two elements selected from the group consisting of B, Si, Sn, Bi, and Ge.

8 . The positive electrode active material for a secondary battery of claim 1 , wherein the lithium compound of Formula 3 comprises any one selected from the group consisting of LiBO 2 and Li 2 B 4 O 7 , or a mixture of at least two thereof.

9 . The positive electrode active material for a secondary battery of claim 1 , wherein the second surface-treated layer is formed to have a surface area of 25% or more to less than 100% with respect to an entire surface area of the core with the first surface-treated layer formed thereon.

10 . The positive electrode active material for a secondary battery of claim 1 , wherein the secondary surface-treated layer has an average thickness ratio of 0.001 to 0.1 with respect to a radius of the core.

11 . The positive electrode active material for a secondary battery of claim 1 , wherein the core is secondary particles obtained through agglomeration of two or more of primary particles.

12 . The positive electrode active material for a secondary battery of claim 1 , wherein M4 element of the lithium oxide of Formula 2 is doped into the core, and the M4 element exhibits a concentration gradient in which an M4 concentration decreases from the surface of the core toward an inside thereof.

13 . The positive electrode active material for a secondary battery of claim 1 , wherein at least any one of metal element among the nickel, M1, and cobalt exhibits a concentration gradient in which a concentration thereof varies inside the core.

14 . The positive electrode active material for a secondary battery of claim 1 , wherein each of the nickel, M1, and cobalt exhibits a concentration gradient in which a concentration thereof independently varies over an entirety of the core,
the nickel has a concentration gradient in which a nickel concentration decreases toward the surface of the core from a center thereof, and the cobalt and M1 have concentration gradients in which each of concentrations of the cobalt and M1 independently increases toward the surface of the core from the center thereof.

15 . The positive electrode active material for a secondary battery of claim 1 , wherein the M1 is manganese (Mn).

16 . (canceled)

17 . (canceled)

18 . (canceled)

19 . A method for preparing the positive electrode active material for a secondary battery according to claim 1 , the method comprising:
preparing a precursor by reacting a nickel raw material, a cobalt raw material and an M1 raw material (where M1 is any one element selected from the group consisting of Al and Mn); forming a first surface-treated layer including an oxide of Formula 2 below, on a surface of a core including a lithium composite metal oxide of Formula 1 below, by mixing the precursor with a lithium raw material and an M3 raw material (where M3 is any one or at least two elements selected from the group consisting of W, Mo and Cr), and firing the resultant mixture; and forming a second surface-treated layer including a lithium compound of Formula 3 below, on the core with the first surface-treated layer formed thereon,
Li a Ni 1-x-y Co x M1 y M3 z M2 w O 2   [Formula 1]

Li m M4O (m+n)/2   [Formula 2]

Li p M5 q A r   [Formula 3]

(in Formulae 1 to 3, A, M1 to M5, a, x, y, z, w, m, n, p and q are the same as those defined in claim 1 ).

20 . The method of claim 19 , wherein the preparing of the precursor is performed through reaction by adding an ammonium cation-containing complexing agent and a basic compound into a metal-containing solution which is obtained by mixing a nickel raw material, a cobalt raw material, and an M1 raw material.

21 . The method of claim 20 , wherein an additional metal-containing solution including nickel, cobalt, M1, and M3, in concentrations of which are different from those in the metal-containing solution, is further added to the metal-containing solution.

22 . The method of claim 19 , wherein the lithium raw material is used such that a molar ratio (molar ratio of lithium/metal element) of lithium included in the lithium raw material and a metal element included in the precursor is 1.0 or more.

23 . (canceled)

24 . (canceled)

25 . The method of claim 19 , wherein the forming of the second surface-treated layer comprises performing surface-treatment on the core with the first surface-treated layer formed thereon, by using a composition including the lithium compound of Formula 3, and then performing heat treatment.

26 . (canceled)

27 . (canceled)

Assignees

• Lg Chemical Ltd

Inventors

• Shin Ju Kyung
• Jung Wang Mo
• Park Byung Chun
• Ryu Ji Hoon
• Park Sang Min
• Lee Sang Wook

Classifications

• H01M2200/30

  Preventing polarity reversal · CPC title

• H01M4/04

  Processes of manufacture in general · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/48

  of inorganic oxides or hydroxides · CPC title

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title