Cathode active material for lithium secondary battery, lithium secondary battery and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2022013781-A1
Application number	US-202117468764-A
Country	US
Kind code	A1
Filing date	Sep 8, 2021
Priority date	Jun 18, 2020
Publication date	Jan 13, 2022
Grant date	—

Abstract

A cathode active material for a lithium secondary battery of embodiments of the present invention includes a lithium composite oxide, a first coating part formed on a surface of the lithium composite oxide and containing aluminum, and a second coating part formed on the first coating part and containing boron. Thereby, stability and electrical characteristics of the secondary battery may be improved.

First claim

What is claimed is:

1 . A cathode active material for a lithium secondary battery comprising:
a lithium composite oxide; a first coating part formed on a surface of the lithium composite oxide and containing aluminum; and a second coating part formed on the first coating part and containing boron,
each of the highest intensity and the lowest intensity of an aluminum peak in an Energy Dispersive X-ray Spectroscopy (EDS) spectrum has a deviation of less than 20% based on an average intensity.

2 . The cathode active material for a lithium secondary battery according to claim 1 , wherein, each of the highest intensity and the lowest intensity of an aluminum peak in an Energy Dispersive X-ray Spectroscopy (EDS) spectrum has a deviation of 10% or less based on an average intensity.

3 . The cathode active material for a lithium secondary battery according to claim 1 , wherein an amount of aluminum eluted when dissolving the cathode active material for 5% of the time taken to completely dissolve the cathode active material from the surface is 50% by weight or more, based on an amount of aluminum eluted when the cathode active material is completely dissolved from the surface.

4 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the first coating part contains an excess amount of aluminum compared to boron, and the second coating part contains an excess amount of boron compared to aluminum.

5 . The cathode active material for a lithium secondary battery according to claim 1 , further comprising an intermediate part containing both aluminum and boron between the first coating part and the second coating part.

6 . The cathode active material for a lithium secondary battery according to claim 5 , wherein, is the intermediate part, at least one fragmented ion of LiAlB+, LiAlBOH4+, Li4AlB+ and Li3AlB3O+ is detected upon time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis.

7 . The cathode active material for a lithium secondary battery according to clam 5 , wherein the intermediate part has a tendency that a content of aluminum is decreased and a content of boron is increased from the first coating part side to the second coating part side.

8 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the first coating part comprises an amorphous aluminum-containing oxide.

9 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the first coating part comprises at least one of amorphous Al2O3, lithium-aluminum oxide, AlOOH, and Al(OH)3.

10 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the second coating part comprises an amorphous boron-containing oxide.

11 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the second coating part comprises at least one of amorphous lithium-boron oxide, LiBO, Li2BO2, Li2B4O7 and Li4BO3.

12 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the lithium composite oxide contains nickel, and a molar fraction of nickel is the lithium composite oxide among the elements except for lithium and oxygen is 0.7 or more.

13 . The cathode active material for a lithium secondary battery according to claim 1 , wherein the lithium composite oxide is represented by Formula I below:
LiαNiyMzO2-β  [Formula 1]
(In Formula 1, M may be at least one selected from the group consisting of Al, Ti, W, B, F, P, Mg, Mn, Co, V, Cu, Zr, Nb, Mo, Sr, and S, and α, β, y, and z may be in a range of 0.7≤α≤1.1, −0.1≤β≤0.5, 0.7≤y≤0.95, and 0.95<y+z≤1.1, respectively).

14 . The cathode active material for a lithium secondary battery according to claim 1 , wherein ac aluminum content of the first coating part is 500 to 2,000 ppm based on a total weight of the cathode active material.

15 . The cathode active material for a lithium secondary battery according to claim 1 , wherein a boron content of the second coating part is 200 to 1,200 ppm based on a total weight of the cathode active material.

16 . A method of manufacturing a cathode active material for a lithium secondary battery comprising:
forming a preliminary cathode active material including an aluminum-containing coating part by wet coating a lithium composite oxide with an aluminum source; and forming a boron-containing coating part on the aluminum-containing coating part by dry reacting the preliminary cathode active material with a boron source.

17 . The method of manufacturing a cathode active material for a lithium secondary battery according to claim 16 , wherein the lithium composite oxide is represented by Formula 1 below:
LiαNiyMzO2-β  [Formula 1]
(In Formula 1, M may be at least one selected from the group consisting of Al, Ti, W, B, F, P, Mg, Mn, Co, V, Cu, Zr, Nb, Mo, Sr, and S, and α, β, y, and z may be in a range of 0.7≤α≤1.1, −0.1≤β≤0.5, 0.7≤y≤0.95, and 0.95<y+z≤1.1, respectively).

18 . The method of manufacturing a cathode active material for a lithium secondary battery according to 16 , wherein the wet coating comprises mixing the lithium composite oxide with an aluminum source solution in which a water-soluble aluminum source is dissolved, and then drying the same.

19 . The method of manufacturing a cathode active material for a lithium secondary battery according to claim 16 , wherein the aluminum source includes at least one of Al2(SO4)3, LiAlO2 and NaAlO2.

20 . The method of manufacturing a cathode active material for a lithium secondary battery according to claim 18 , wherein the drying is performed at 110 to 300° C.

21 . The method of manufacturing a cathode active material for a lithium secondary battery according to claim 16 , wherein the boron source includes at least one of HBO2, H3BO3 and H2B4O7.

22 . The method of manufacturing a cathode active material for a lithium secondary battery according to claim 16 , wherein the dry reaction is performed at a temperature of 250 to 400° C.

23 . A lithium secondary battery comprising:
an electrode cell which comprises a cathode including the cathode active material for a lithium secondary battery according to claim 1 , an anode, and a separation membrane interposed between the cathode and the anode; a case configured to house the electrode cell; and an electrolyte in which the electrode cell is impregnated in the case.

Assignees

• Sk Innovation Co Ltd

Inventors

• Choi Ji Hoon
• Kim Sang Bok
• Kim Jik Soo
• Kweon Hee Jun
• Park Sung Soon

Classifications

• C01P2006/40

  Electric properties · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01P2002/89

  by mass-spectroscopy · CPC title

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01G53/50

  of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 · CPC title