Positive active material for rechargeable lithium battery, positive electrode including same and rechargeable lithium battery including same

Patent metadata

Field	Value
Publication number	US-2019260017-A1
Application number	US-201916279306-A
Country	US
Kind code	A1
Filing date	Feb 19, 2019
Priority date	Feb 19, 2018
Publication date	Aug 22, 2019
Grant date	—

Abstract

In Chemical Formula 2, 0.90≤a1≤1.8, 0≤x1≤0.7, and M1 may be Mg, Co, Ni, or a combination thereof.

First claim

What is claimed is:

1 . A positive active material for a rechargeable lithium battery, comprising:
a first positive active material and a second positive active material, wherein the first positive active material comprises at least one nickel-based lithium composite oxide, and the second positive active material is represented by Chemical Formula 2 and has an average particle diameter of about 300 nm to about 600 nm:
Li a1 Fe 1-x1 M1 x1 PO 4 ,  [Chemical Formula 2]

wherein, in Chemical Formula 2, 0.90≤a1≤1.8, 0≤x1≤0.7, and M1 is magnesium (Mg), cobalt (Co), nickel (Ni), or a combination thereof.

2 . The positive active material of claim 1 , wherein the nickel-based lithium composite oxide comprises a compound represented by Chemical Formula 1:
Li a2 (Ni 1-x2-y-z Co x2 Me y M2 z )O 2 ,  [Chemical Formula 1]
wherein, in Chemical Formula 1:
M2 is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), and zirconium (Zr),
0.95≤a2≤1.3, x2<(1−x2−y−z), y<(1−x2−y−z), 0<x2<1, 0≤y<1, 0≤z<1, and
Me is at least one of Mn and Al.

3 . The positive active material of claim 1 , wherein the nickel-based lithium composite oxide is represented by at least one selected from LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.5 Co 0.2 Mn 0.3O2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.85 Co 0.1 Al 0.05 O 2 , and LiNi 0.95 Co 0.025 Al 0.025 O 2 .

4 . The positive active material of claim 1 , wherein the first positive active material comprises at least two nickel-based lithium composite oxides having a different average particle diameter.

5 . The positive active material of claim 1 , wherein an amount of the second positive active material is about 1 wt % to about 15 wt % based on a total amount of the positive active material for a rechargeable lithium battery.

6 . A positive electrode for a rechargeable lithium battery, comprising:
a current collector; and a positive active material layer on at least one surface of the current collector; wherein the positive active material layer comprises the positive active material for the rechargeable lithium battery of claim 1 .

7 . The positive electrode of claim 6 , wherein the positive electrode further comprises a functional layer on the positive active material layer,
wherein the functional layer comprises a compound represented by Chemical Formula 3 and a binder:
Li a3 Fe 1-x3 M3 x3 PO 4 ,  [Chemical Formula 3]

wherein, in Chemical Formula 3, 0.90≤a3≤1.8, 0≤x3≤0.7, and M3 is Mg, Co, Ni, or a combination thereof.

8 . The positive electrode of claim 7 , wherein an average particle diameter of the compound represented by Chemical Formula 3 is about 0.2 μm to about 1 μm.

9 . The positive electrode of claim 7 , wherein the binder comprises at least one selected from a styrene-butadiene rubber, an acrylate-based compound, an imide-based compound, a polyvinylidene fluoride-based compound, a polyvinylpyrrolidone-based compound, a nitrile-based compound, an acetate-based compound, a cellulose-based compound, and a cyano-based compound.

10 . The positive electrode of claim 7 , wherein a ratio of a thickness of the positive active material layer to a thickness of the functional layer is about 30:1 to about 10:1.

11 . The positive electrode of claim 7 , wherein:
the functional layer further comprises polymer particles, and an amount of the polymer particles is about 20 wt % to about 70 wt % based on a total amount of the functional layer.

12 . The positive electrode of claim 11 , wherein the polymer particles comprise at least one selected from polyethylene wax, acryl-based particles having a glass transition temperature (T g ) of less than or equal to about 100° C., and a combination thereof.

13 . A rechargeable lithium battery, comprising:
the positive electrode of claim 6 ; a negative electrode; and an electrolyte solution.

14 . The rechargeable lithium battery of claim 13 , wherein the nickel-based lithium composite oxide comprises a compound represented by Chemical Formula 1:
Li a2 (Ni 1-x2-y-z Co x2 Me y M2 z )O 2 ,  [Chemical Formula 1]
wherein, in Chemical Formula 1:
M2 is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), and zirconium (Zr),
0.95≤a2≤1.3, x2<(1−x2−y−z), y<(1−x2−y−z), 0<x2<1, 0≤y<1, 0≤z<1, and
Me is at least one of Mn and Al.

15 . The rechargeable lithium battery of claim 13 , wherein the nickel-based lithium composite oxide is represented by at least one selected from LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.5 Co 0.2 Mn 0.3O2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.85 Co 0.1 Al 0.05 O 2 , and LiNi 0.95 Co 0.025 Al 0.025 O 2 .

16 . The rechargeable lithium battery of claim 13 , wherein the first positive active material comprises at least two nickel-based lithium composite oxides having a different average particle diameter.

17 . The rechargeable lithium battery of claim 13 , wherein an amount of the second positive active material is about 1 wt % to about 15 wt % based on a total amount of the positive active material for a rechargeable lithium battery.

18 . The rechargeable lithium battery of claim 13 , wherein the positive electrode further comprises a functional layer on the positive active material layer,
wherein the functional layer comprises a compound represented by Chemical Formula 3 and a binder:
Li a3 Fe 1-x3 M3 x3 PO 4 ,  [Chemical Formula 3]

wherein, in Chemical Formula 3, 0.90≤a3≤1.8, 0≤x3≤0.7, and M3 is Mg, Co, Ni, or a combination thereof.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Yoo Heeeun
• Nam Junghyun
• Seok Hoon
• Yoon Yeonhee
• Lee Kyuseo
• Jeon Bokkyu
• Ha Jaehwan

Classifications

• H01M10/0525

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

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title