Positive Electrode Including Positive Electrode Additive, Method of Manufacturing Positive Electrode, and Lithium Secondary Battery Including Positive Electrode

Patent metadata

Field	Value
Publication number	US-2023261168-A1
Application number	US-202218003788-A
Country	US
Kind code	A1
Filing date	May 6, 2022
Priority date	Jun 2, 2021
Publication date	Aug 17, 2023
Grant date	—

Abstract

Provided are a positive electrode including a positive electrode additive, a method of manufacturing the positive electrode, and a lithium secondary battery including the positive electrode. A coating temperature of a slurry is adjusted when the positive electrode is manufactured, and thus the deformation of the positive electrode additive due to temperature is minimized, and accordingly, structural deformation of the positive electrode additive included in the positive electrode is prevented.

First claim

1 . A method of manufacturing a positive electrode for a lithium secondary battery, the method comprising:
applying a first slurry containing a positive electrode active material, a positive electrode additive, a conductive material, and a binder on at least one surface of a current collector and forming a first mixture layer; and applying a second slurry containing a positive electrode active material, a conductive material, and a binder on the current collector on which the first mixture layer is formed and forming a second mixture layer, wherein the forming of the first mixture layer and the forming of the second mixture layer includes a process of controlling a temperature of the first slurry to 40° C. or less and a process of controlling a temperature of the second slurry to 40° C. or less, respectively, and wherein Expression 1 below is satisfied when X-ray diffraction (XRD) analysis is performed on the first mixture layer:
A/B≤ 1  [Expression 1]

wherein A represents an intensity of a strongest peak among peaks appearing in a range of 2θ=38.5±0.1°, and B represents an intensity of a strongest peak among peaks appearing in a range of 2θ=47.9±0.1°.

2 . The method of claim 1 , wherein the forming of the first mixture layer and the forming of the second mixture layer include a process of controlling a temperature of the first slurry to be in a range of 10° C. to 40° C. and a process of controlling a temperature of the second slurry to be in a range of 10° C. to 40° C., respectively.

3 . The method of claim 1 , further comprising:
a first rolling operation of rolling the first mixture layer after the forming of the first mixture layer; and a second rolling operation of rolling the second mixture layer after the forming of the second mixture layer.

4 . The method of claim 3 , wherein:
the first rolling operation is performed at a speed of 0.5 m/s to 6 m/s; the second rolling operation is performed at a speed of 2 m/s to 7 m/s; and the second rolling operation is performed at a greater speed than the first rolling operation.

5 . The method of claim 3 , wherein:
the first rolling operation is performed at a temperature of 10° C. to 40° C.; and the second rolling operation is performed at a temperature of 40° C. to 100° C.

6 . A positive electrode for a lithium secondary battery, comprising a current collector and a mixture layer formed on at least one surface of the current collector,
wherein the mixture layer has a two-layer structure in which a first mixture layer and a second mixture layer are laminated, wherein the first mixture layer includes a positive electrode active material, a positive electrode additive, a conductive material, and a binder, and wherein Expression 1 below is satisfied when X-ray diffraction (XRD) analysis is performed on the first mixture layer:
A/B≤ 1  [Expression 1]

wherein A represents an intensity of a strongest peak among peaks appearing in a range of 2θ=38.5±0.1°, and B represents an intensity of a strongest peak among peaks appearing in a range of 2θ=47.9±0.1°.

7 . The positive electrode of claim 6 , wherein the positive electrode additive is a lithium cobalt oxide represented by Chemical Formula 1 below:
Li p Co (1-q) M 1 q O 4   [Chemical Formula 1]
wherein in Chemical Formula 1 above, M 1 denotes one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and p and q are 5≤p≤7 and 0≤q≤0.5, respectively.

8 . The positive electrode of claim 7 , wherein the positive electrode additive has a tetragonal structure with a space group of P4 2 /nmc.

9 . The positive electrode of claim 6 , wherein a content of the positive electrode additive ranges from 0.1 to 5 wt % with respect to a total weight of the first mixture layer.

10 . The positive electrode of claim 6 , wherein the positive electrode active material is a lithium nickel composite oxide represented by Chemical Formula 2 below:
Li x [Ni y Co z Mn w M 2 v ]O u   [Chemical Formula 2]
wherein in Chemical Formula 2 above, M 2 denotes one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and x, y, z, w, v, and u are 1.0≤x≤1.30, 0.1≤y<0.95, 0.01<z≤0.5, 0.01<w≤0.5, 0≤v≤0.2, 1.5≤u≤4.5, respectively.

11 . The positive electrode of claim 6 , wherein:
an average thickness (D1) of the first mixture layer ranges from 0.1 μm to 20 μm; and an average thickness (D2) of the second mixture layer ranges from 50 μm to 300 μm.

12 . A lithium secondary battery comprising:
the positive electrode according to claim 6 ; a negative electrode; and a separator interposed between the positive electrode and the negative electrode.

13 . The lithium secondary battery of claim 12 , wherein the negative electrode comprises a negative electrode current collector and a negative electrode mixture layer positioned on the negative electrode current collector comprising a negative electrode active material,
wherein the negative electrode active material comprises a carbon material and a silicon material.

14 . The lithium secondary battery of claim 13 , wherein the silicon material is included in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the negative electrode mixture layer.

Assignees

• Lg Energy Solution Ltd

Inventors

• Kim Gwang Yeon
• Oh Sang Seung
• Kim Hye Hyeon
• Jo Chi Ho

Classifications

• H01M4/0404 Primary

  by coating on electrode collectors · CPC title

• H01M4/0435

  Rolling or calendering · 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

• H01M4/131 Primary

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