Manufacturing method of cathode active material, and cathode active material for lithium secondary battery manufactured thereby

Patent metadata

Field	Value
Publication number	US-2016013476-A1
Application number	US-201414437079-A
Country	US
Kind code	A1
Filing date	Oct 29, 2014
Priority date	Oct 29, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Provided are a method of preparing a cathode active material including coating a surface of a lithium transition metal oxide with a lithium boron oxide by dry mixing the lithium transition metal oxide and a boron-containing compound and performing a heat treatment, and a cathode active material prepared thereby.
A method of preparing a cathode active material according to an embodiment of the present invention may easily transform lithium impurities present in a lithium transition metal oxide into a structurally stable lithium boron oxide by performing a heat treatment near the melting point of a boron-containing compound.
Also, a coating layer may be formed in which the lithium boron oxide is uniformly coated in an amount proportional to the used amount of the boron-containing compound even at a low heat treatment temperature.

First claim

1 . A method of preparing a cathode active material, the method comprising coating a surface of a lithium transition metal oxide with a lithium boron oxide by dry mixing the lithium transition metal oxide and a boron-containing compound and performing a heat treatment.

2 . The method of claim 1 , wherein the heat treatment is performed in a temperature range of 130° C. to 300° C.

3 . The method of claim 2 , wherein the heat treatment is performed in a temperature range of 130° C. to 200° C.

4 . The method of claim 2 , wherein the boron-containing compound is transformed into a lithium boron oxide through a reaction with at least a portion of lithium impurities in the lithium transition metal oxide by the heat treatment.

5 . The method of claim 2 , wherein a portion of elemental boron (B) of the lithium boron oxide is doped into the lithium transition metal oxide by the heat treatment, and an amount of the B has a concentration gradient gradually decreasing from the surface of the lithium transition metal oxide to inside thereof.

6 . The method of claim 4 , wherein the lithium impurities comprise LiOH, Li 2 CO 3 , or a mixture thereof.

7 . The method of claim 1 , wherein the mixing is performed by a mortar grinder mixing method or a mechanical milling method.

8 . The method of claim 7 , wherein the mixing by the mechanical milling method is performed by using a roll mill, ball mill, high energy ball mill, planetary mill, stirred ball mill, vibrating mill, or jet mill.

9 . The method of claim 1 , wherein the boron-containing compound comprises any one selected from the group consisting of H 3 BO 3 , B 2 O 3 , C 6 H 5 B(OH) 2 , (C 6 H 5 O) 3 B, [CH 3 (CH 2 ) 3 O] 3 B, C 13 H 19 BO 3 , C 3 H 9 B 3 O 6 , and (C 3 H 7 O) 3 B, or a mixture of two or more thereof.

10 . The method of claim 1 , wherein the boron-containing compound is used in an amount of 0.05 wt % to 1 wt % based on a total weight of the lithium transition metal oxide.

11 . The method of claim 1 , wherein the lithium boron oxide is LiBO 2 , Li 2 B 4 O 7 , or a mixture thereof.

12 . The method of claim 1 , wherein the lithium transition metal oxide is represented by Chemical Formula 1:
Li 1+a [Ni x Mn y Co z M v ]O 2-c A c   <Chemical Formula 1>
where M is any one selected from the group consisting of aluminum (Al), zirconium (Zr), zinc (Zn), titanium (Ti), magnesium (Mg), gallium (Ga), and indium (In), or two or more elements thereof; A is at least one selected from the group consisting of phosphorus (P), fluorine (F), sulfur (S), and nitrogen (N), and 0≦x≦1.0, 0≦y<0.6, 0≦z<0.6, 0≦v≦0.1, 0≦a<0.3, 0≦c≦0.2, and a+x+y+z+v=1.

13 . A cathode active material comprising:
a lithium transition metal oxide; and a coating layer including a lithium boron oxide on a surface of the lithium transition metal oxide.

14 . The cathode active material of claim 13 , wherein the coating layer comprises elemental boron (B) in an amount of 100 ppm to 2,000 ppm.

15 . The cathode active material of claim 13 , wherein the coating layer comprises elemental B in an amount of 250 ppm to 1,100 ppm.

16 . The cathode active material of claim 13 , wherein a thickness of the coating layer is in a range of 10 nm to 1,000 nm.

17 . The cathode active material of claim 13 , wherein a portion of elemental B of the lithium boron oxide is further included in the lithium transition metal oxide.

18 . The cathode active material of claim 17 , wherein the lithium transition metal oxide is represented by Chemical Formula 3, and, in Chemical Formula 3, w has a concentration gradient gradually decreasing from the surface of the lithium transition metal oxide to inside thereof:
Li 1+a [Ni x Mn y Co z B w M v ]O 2-c A c   <Chemical Formula 3>
where M is any one selected from the group consisting of aluminum (Al), zirconium (Zr), zinc (Zn), titanium (Ti), magnesium (Mg), gallium (Ga), and indium (In), or two or more elements thereof; A is at least one selected from the group consisting of phosphorus (P), fluorine (F), sulfur (S), and nitrogen (N), and 0≦x≦1.0, 0≦y<0.6, 0≦z<0.6, 0≦v≦0.1, 0≦a<0.3, 0≦c≦0.2, a+x+y+z+v=1, and 0≦w≦0.1.

19 . The cathode active material of claim 13 , wherein the cathode active material comprises lithium impurities in an amount of less than 0.3 wt % based on a total weight of the cathode active material.

20 . The cathode active material of claim 13 , wherein the lithium boron oxide is LiBO 2 , Li 2 B 4 O 7 , or a mixture thereof.

21 . A cathode comprising the cathode active material of claim 13 .

22 . A lithium secondary battery comprising the cathode of claim 21 .

Assignees

• Lg Chemical Ltd

Inventors

• Oh Hyun Jin
• Shin Ho Suk
• Lim Jin Hyung
• Lee Dong Hun
• Jin Joo Hong
• Jung Wang Mo

Classifications

• H01M4/131

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

• H01M4/485 Primary

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/1391

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