Cathode active material, preparation method thereof, and lithium secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-2016028077-A1
Application number	US-201414437085-A
Country	US
Kind code	A1
Filing date	Oct 31, 2014
Priority date	Oct 31, 2013
Publication date	Jan 28, 2016
Grant date	—

Abstract

Provided is a cathode active material including lithium transition metal oxide particles and composite particles, wherein the composite particles include any one selected from the group consisting of yttria stabilized zirconia (YSZ), gadolinia-doped ceria (GDC), lanthanum strontium gallate magnesite (LSGM), lanthanum strontium manganite (LSM), and nickel (Ni)—YSZ, or a mixture of two or more thereof, and the cathode active material includes the composite particles having a single-phase peak when analyzed by X-ray diffraction (XRD).
A cathode active material according to an embodiment of the present invention may not only minimize the reduction in capacity or output of a secondary battery, but may also further improve life characteristics.

First claim

1 . A cathode active material comprising:
lithium transition metal oxide particles; and composite particles, wherein the composite particles comprise any one selected from the group consisting of yttria stabilized zirconia (YSZ), gadolinia-doped ceria (GDC), lanthanum strontium gallate magnesite (LSGM), lanthanum strontium manganite (LSM), calcium (Ca)-doped zirconia or calcia stabilized zirconia (CSZ), scandium (Sc)-doped zirconia (SSZ), and nickel (Ni)—YSZ, or a mixture of two or more thereof, and the composite particles have a single-phase peak when analyzed by X-ray diffraction (XRD).

2 . The cathode active material of claim 1 , wherein the composite particles are coated on outer surfaces of the lithium transition metal oxide particles to form a coating layer.

3 . The cathode active material of claim 1 , wherein the composite particles are included in the lithium transition metal oxide particles.

4 . The cathode active material of claim 3 , wherein the composite particles have a concentration gradient gradually decreasing from surfaces of the lithium transition metal oxide particles to inside thereof and are composited with the lithium transition metal oxide particles to form a composite.

5 . The cathode active material of claim 4 , wherein an amount of the composite particles in an outer bulk of the lithium transition metal oxide particles is at least 20% or more greater than an amount of the composite particles in an inner bulk of the lithium transition metal oxide particles, and the inner bulk, as a center of the lithium transition metal oxide particles and a peripheral region thereof, is a region including 50% of the number of transition metal atoms of the entire particles.

6 . The cathode active material of claim 4 , wherein the composite particles are included in a thickness of 1 nm to 5,000 nm in a direction from the surfaces toward the inside of the lithium transition metal oxide particles.

7 . The cathode active material of claim 2 , wherein the composite particles are coated to a thickness of 1 nm to 5,000 nm from the outer surfaces of the lithium transition metal oxide particles.

8 . The cathode active material of claim 1 , wherein the composite particles are coated on outer surfaces of the lithium transition metal oxide particles to form a coating layer and are included with the lithium transition metal oxide particles in the lithium transition metal oxide particles.

9 . The cathode active material of claim 8 , wherein the composite particles are included in an amount of 50 ppm to 30,000 ppm based on a total amount of the cathode active material.

10 . The cathode active material of claim 8 , wherein the composite particles have a concentration gradient gradually decreasing from the surfaces of the lithium transition metal oxide particles to inside thereof and are composited with the lithium transition metal oxide particles to form a composite.

11 . The cathode active material of claim 1 , wherein the composite particles comprise any one selected from the group consisting of YSZ, CSZ, and SSZ, or two or more thereof.

12 . The cathode active material of claim 11 , wherein the YSZ comprises oxygen vacancies proportional to an amount of an yttrium (Y) element.

13 . The cathode active material of claim 12 , wherein the YSZ is Zr (1-x) Y x O 2-x/2 (0.01≦x≦0.30).

14 . The cathode active material of claim 12 , wherein the oxygen vacancies are included in an amount of 0.25 ppm to 4,500 ppm based on a total amount of the cathode active material.

15 . The cathode active material of claim 11 , wherein the SSZ is (ZrO 2 ) 1-2x (Sc 2 O 3 ) x , (ZrO 2 ) 1-2x (Sc 2 O 3 ) x-z (Y 2 O 3 ) z , or (ZrO 2 ) 1-2x-z (Sc 2 O 3 ) x (CeO 2 ) z (0.01≦x≦0.2)(0.01≦z≦0.1), and the CSZ comprises CaO in an amount of 2 wt % to 17 wt % based on a total weight of the CSZ.

16 . The cathode active material of claim 13 , wherein x is between 0.03 and 0.20.

17 . The cathode active material of claim 2 , wherein the coating layer further comprises an oxide including at least one element of calcium (Ca), niobium (Nb), tungsten (W), magnesium (Mg), titanium (Ti), boron (B), molybdenum (Mo), scandium (Sc), and zirconium (Zr).

18 . The cathode active material of claim 1 , wherein the lithium transition metal oxide particles comprise a compound of Chemical Formula 1:
Li (1+a) Ni (1-b-c) Mn (b) Co (c) M′ (s) M″ (v) O 2   <Chemical Formula 1>
where M′ comprises any one selected from the group consisting of Y, Zr, lanthanum (La), strontium (Sr), gallium (Ga), Mg, manganese (Mn), Ca, Sc, and Ni, or mixed elements of two or more thereof, M″ is at least one element of Ca, Nb, W, Mg, Ti, B, Mo, Sc, and Zr, and 0≦a<0.2, 0≦b≦1, 0≦c≦1, 0≦s≦0.2, and 0≦v≦0.2.

19 . The cathode active material of claim 18 , wherein, in Chemical Formula 1, M′ comprises any one selected from the group consisting of Y, Zr, Ca, Sc, and Ni, or mixed elements of two or more thereof.

20 . The cathode active material of claim 18 , wherein s and v have a concentration gradient gradually decreasing from surfaces of the lithium transition metal oxide particles to inside thereof.

21 . The cathode active material of claim 1 , wherein an average particle diameter of the cathode active material is in a range of 3 μm to 30 μm.

22 . The cathode active material of claim 1 , wherein the cathode active material has a compressive strength of 80 MPa to 500 MPa under a pressure of 0.5 mN to 10 mN.

23 . A method of preparing a cathode active material, the method comprising mixing lithium transition metal oxide particles and composite particles and heat treating the mixture,
wherein the composite particles comprise any one selected from the group consisting of yttria stabilized zirconia (YSZ), gadolinia-doped ceria (GDC), lanthanum strontium gallate magnesite (LSGM), lanthanum strontium manganite (LSM), calcium (Ca)-doped zirconia or calcia stabilized zirconia (CSZ), scandium (Sc)-doped zirconia (SSZ), and nickel (Ni)—YSZ, or a mixture of two or more thereof.

24 . The method of claim 23 , wherein the composite particles comprise any one selected from the group consisting of YSZ, CSZ, and SSZ, or two or more thereof.

25 . The method of claim 24 , wherein the YSZ is Zr (1-x) Y x O 2-x/2 (0.01≦x≦0.30).

26 . The method of claim 24 , wherein the SSZ is (ZrO 2 ) 1-2x (SC 2 O 3 ) x , (ZrO 2 ) 1-2x (Sc 2 O 3 ) x-z (Y 2 O 3 ) z , or (ZrO 2 ) 1-2x-z (Sc 2 O 3 ) x (CeO 2 ) z (0.01≦x≦0.2)(0.01≦z≦0.1), and the CSZ comprises CaO in an amount of 2 wt % to 17 wt % based on a total weight of the CSZ.

27 . The method of claim 23 , wherein the heat treatment is performed in a temperature range of 100° C. to 1,200° C.

28 . The method of claim 27 , wherein the heat treatment is performed in a temperature range of 100° C. to 600° C.

29 . The method of claim 28 , wherein a coating layer is formed on surfaces of the lithium transition metal oxide particles by the heat treatment, the coating layer comprises any one selected from the group consisting of YSZ, GDC, LSGM, LSM, CSZ, SSZ, and Ni—YSZ, or a mixture of two or more thereof, and the cathode active material comprises composite particles having a single-phase peak when analyzed by X-ray diffraction (XRD).

30 . The method of claim 27 , wherein the heat treatment is performed in a temperature range of 600° C. to 1,200° C.

Assignees

• Lg Chemical Ltd

Inventors

• Kwak Ick Soon
• Cho Seung Beom
• Chae Hwa Seok
• Yoon Yeo June

Classifications

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M10/052

  Li-accumulators · CPC title