Secondary battery

Patent metadata

Field	Value
Publication number	US-2025357481-A1
Application number	US-202318867028-A
Country	US
Kind code	A1
Filing date	May 31, 2023
Priority date	Jun 8, 2022
Publication date	Nov 20, 2025
Grant date	—

Abstract

A positive electrode active material which inhibits the discharge capacity from decreasing during charge and discharge cycles and a secondary battery using the positive electrode active material are provided. A highly safe secondary battery is provided. The secondary battery includes a positive electrode active material, which contains lithium cobalt oxide containing nickel and magnesium. The detected amounts of nickel and magnesium in a surface portion of the positive electrode active material are larger than the detected amounts of nickel and magnesium in an inner portion of the positive electrode active material. The distribution of nickel and the distribution of magnesium overlap with each other in the surface portion of the positive electrode active material. In the above, the positive electrode active material preferably further contains fluorine and the detected amount of fluorine in the surface portion of the positive electrode active material is preferably larger than the detected amount of fluorine in the inner portion of the positive electrode active material.

First claim

1 . A lithium-ion secondary battery comprising:
a positive electrode, wherein the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises lithium cobalt oxide comprising nickel and magnesium, wherein a detected amount of nickel in a surface portion of the positive electrode active material is larger than a detected amount of nickel in an inner portion of the positive electrode active material, wherein a detected amount of magnesium in the surface portion of the positive electrode active material is larger than a detected amount of magnesium in the inner portion of the positive electrode active material, and wherein a distribution of nickel and a distribution of magnesium overlap with each other in the surface portion of the positive electrode active material.

2 . The lithium-ion secondary battery according to claim 1 ,
wherein nickel is detected at a plane other than a (001) plane of lithium cobalt oxide in the surface portion of the positive electrode active material.

3 . The lithium-ion secondary battery according to claim 2 ,
wherein, in EDX line analysis, a difference between a depth of a peak of a detected amount of nickel and a depth of a peak of a detected amount of magnesium in the surface portion of the positive electrode active material is less than or equal to 3 nm.

4 . The lithium-ion secondary battery according to claim 3 ,
wherein the positive electrode active material comprises aluminum, and wherein in an EDX line analysis profile of nickel, magnesium, and aluminum comprised in the positive electrode active material, a maximum value of a detected amount of aluminum is observed at an inner portion than a maximum value of a detected amount of nickel and a maximum value of a detected amount of magnesium, wherein when a peak width at a height of ⅕ of the maximum value of a detected amount of aluminum is divided to two parts by a vertical line drawn from the maximum value to the horizontal axis, a peak width W c on an inner side is larger than a peak width W s on a surface side.

5 . The lithium-ion secondary battery according to claim 1 ,
wherein in a battery in which a counter electrode of the positive electrode is lithium, when the positive electrode is analyzed by powder X-ray diffraction using a CuKα1 ray in a state where the battery is charged to 4.6 V, a diffraction pattern of the positive electrode active material comprises a peak at least at 2θ of greater than or equal to 19.13 and less than 19.37 and 20 of greater than or equal to 45.37° and less than 45.57°.

6 . The lithium-ion secondary battery according to claim 5 ,
wherein the positive electrode active material comprises titanium, and wherein a detected amount of titanium in the surface portion of the positive electrode active material is larger than a detected amount of titanium in the inner portion of the positive electrode active material.

7 . The lithium-ion secondary battery according to claim 5 ,
wherein the positive electrode active material comprises fluorine, and wherein a detected amount of fluorine in the surface portion of the positive electrode active material is larger than a detected amount of fluorine in the inner portion of the positive electrode active material.

8 . The lithium-ion secondary battery according to claim 6 ,
wherein the positive electrode active material comprises fluorine, and wherein a detected amount of fluorine in the surface portion of the positive electrode active material is larger than a detected amount of fluorine in the inner portion of the positive electrode active material.

9 . A lithium-ion secondary battery comprising:
a positive electrode, wherein the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises lithium cobalt oxide comprising nickel, magnesium, and aluminum, and wherein in an EDX line analysis profile of nickel, magnesium, and aluminum comprised in the positive electrode active material, a maximum value of a detected amount of aluminum is observed at an inner portion than a maximum value of a detected amount of nickel and a maximum value of a detected amount of magnesium.

10 . The lithium-ion secondary battery according to claim 9 , wherein when a peak width at a height of ⅕ of the maximum value of a detected amount of aluminum is divided to two parts by a vertical line drawn from the maximum value to the horizontal axis, a peak width W c on an inner side is larger than a peak width W s on a surface side.

Assignees

• Semiconductor Energy Lab

Inventors

• Yamazaki Shunpei
• Momma Yohei
• Muratsubaki Shotaro
• Takahashi Tatsuyoshi
• Mikami Mayumi
• Saito Jo
• Ochiai Teruaki
• Kawatsuki Atsushi

Classifications

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/131

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

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/582

  Halogenides · CPC title

• H01M10/0525

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