Positive electrode and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-2024014392-A1
Application number	US-202218029661-A
Country	US
Kind code	A1
Filing date	Jan 7, 2022
Priority date	Jan 8, 2021
Publication date	Jan 11, 2024
Grant date	—

Abstract

Disclosed is a positive electrode including: a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer has a lower layer region facing the positive electrode current collector and containing a first positive electrode active material and a first binder polymer, and an upper layer region facing the lower layer region and containing a second positive electrode active material and a second binder polymer, and the Ni content of the second positive electrode active material in the upper layer region is larger than the Ni content of the first positive electrode active material in the lower layer region. Also disclosed is a lithium secondary battery including the positive electrode.

First claim

1 . A positive electrode comprising:
a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer having:
a lower layer region facing the positive electrode current collector and containing a first positive electrode active material represented by Chemical Formula 1, and a first binder polymer, and
an upper layer region facing the lower layer region and containing a second positive electrode active material represented by Chemical Formula 2, and a second binder polymer, wherein a Ni content of the second positive electrode active material is larger than a Ni content of the first positive electrode active material,
wherein the Chemical Formula 1 and the Chemical Formula 2 are:
Li 1+a [Ni x Mn y Co z ]M1 t O 2   [Chemical Formula 1]

where 0≤a≤0.2, 0.4≤x≤0.9, 0<y<1, 0<z<1, 0≤t<0.1 and x+y+z+t=1, and M1 includes at least one element selected from the group consisting of Co, Mn, Ni, Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, W, Sn, Hf, Nd, and Gd,
Li 1+b [Ni u Mn v Co w ]M2 s O 2   [Chemical Formula 2]

where 0≤b≤0.2, 0.4≤u≤0.9, 0<v<1, 0<w<1, 0≤s<0.1 and u+v+w+s=1, and M2 includes at least one element selected from the group consisting of Co, Mn, Ni, Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, W, Sn, Hf, Nd, and Gd.

2 . The positive electrode according to claim 1 , wherein:
the Ni content of the first positive electrode active material is 40-75 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 80-90 mol % based on a total transition metals of the second positive electrode active material.

3 . The positive electrode according to claim 1 , wherein:
the Ni content of the first positive electrode active material is 50-75 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 81-90 mol % based on a total transition metals of the second positive electrode active material.

4 . The positive electrode according to claim 1 , wherein:
the Ni content of the first positive electrode active material is 65-70 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 86-90 mol % based on a total transition metals of the second positive electrode active material.

5 . The positive electrode according to claim 1 , wherein a weight ratio of the lower layer region to the upper layer region is 20:80-80:20.

6 . A method for manufacturing a positive electrode, comprising:
preparing:
a slurry for a lower layer containing a first positive electrode active material represented by Chemical Formula 1, a first binder polymer and a first dispersion medium, and
a slurry for an upper layer containing a second positive electrode active material represented by Chemical Formula 2, a second binder polymer and a second dispersion medium, wherein a Ni content of the second positive electrode active material is larger than a Ni content of the first positive electrode active material;
coating the slurry for the lower layer on one surface of a positive electrode current collector, and coating the slurry for the upper layer on the slurry for the lower layer; and drying the coated slurry for the lower layer and the coated slurry for the upper layer at the same time to form a positive electrode active material layer, wherein the Chemical Formula 1 and the Chemical Formula 2 are:
Li 1+a [Ni x Mn y Co z ]M1 t O 2   [Chemical Formula 1]

where 0≤a≤0.2, 0.4≤x≤0.9, 0<y<1, 0<z<1, 0≤t<0.1 and x+y+z+t=1, and M1 includes at least one element selected from the group consisting of Co, Mn, Ni, Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, W, Sn, Hf, Nd, and Gd,
Li 1+b [Ni u Mn v Co w ]M2 s O 2   [Chemical Formula 2]

where 0≤b≤0.2, 0.4≤u≤0.9, 0<v<1, 0<w<1, 0≤s<0.1 and u+v+w+s=1, and M2 includes at least one element selected from the group consisting of Co, Mn, Ni, Al, Fe, V, Cr, Ti, Ta, Mg, Mo, Zr, W, Sn, Hf, Nd, and Gd.

7 . The method according to claim 6 , wherein the Ni content of the first positive electrode active material is 40-75 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 80-90 mol % based on a total transition metals of the second positive electrode active material.

8 . The method according to claim 6 , wherein the Ni content of the first positive electrode active material is 50-75 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 81-90 mol % based on a total transition metals of the second positive electrode active material.

9 . The method according to claim 6 , wherein the Ni content of the first positive electrode active material is 65-70 mol % based on a total transition metals of the first positive electrode active material, and the Ni content of the second positive electrode active material is 86-90 mol % based on a total transition metals of the second positive electrode active material.

10 . A lithium secondary battery comprising the positive electrode as defined in claim 1 .

Assignees

• Lg Energy Solution Ltd

Inventors

• An Ji-Su
• Sung Ki-Won
• Lee Eun-Ju

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

• H01M10/052

  Li-accumulators · CPC title

• H01M4/525 Primary

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

• H01M4/622

  being polymers · CPC title