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CN-122003733-A - Electrode and lithium ion secondary battery

CN122003733ACN 122003733 ACN122003733 ACN 122003733ACN-122003733-A

Abstract

The electrodes (20, 30) are provided with current collectors (22, 32) and active material layers (24, 34) that are in contact with one surfaces of the current collectors (22, 32). The active material layers (24, 34) have main portions (25, 35) and sub portions (26, 36) when viewed in the lamination direction. The auxiliary portions (26, 36) are separated from the main portions (25, 35) and are located at outer peripheral ends of the active material layers (24, 34). The areas of the main portions (25, 35) are larger than the areas of the auxiliary portions (26, 36).

Inventors

  • KATO TAKEHISA
  • OTSUKI KEITARO
  • Tian Hongyu angle

Assignees

  • TDK株式会社

Dates

Publication Date
20260508
Application Date
20241017
Priority Date
20231019

Claims (8)

  1. 1. An electrode, wherein, Comprises a current collector and an active material layer connected to one surface of the current collector, The active material layer has a main portion and a sub portion when viewed from the lamination direction, The auxiliary part is separated from the main part and is positioned at the peripheral end part of the active material layer, The area of the main portion is larger than the area of the auxiliary portion.
  2. 2. The electrode according to claim 1, wherein, The auxiliary portion is located at an outer peripheral corner of the active material layer.
  3. 3. The electrode according to claim 1, wherein, The active material layer has a plurality of the sub-portions.
  4. 4. The electrode according to claim 1, wherein, The area of the main portion is 55% to 88% of the total area of the active material layer.
  5. 5. The electrode according to claim 1, wherein, The side of the main portion facing the auxiliary portion has irregularities when viewed in the stacking direction.
  6. 6. The electrode according to claim 1, wherein, The active material contained in the active material layer is lithium titanate.
  7. 7. The electrode according to claim 1, wherein, The active material contained in the active material layer is lithium cobaltate.
  8. 8. A lithium ion secondary battery, wherein, An electrode and an electrolyte according to any one of claims 1 to 7.

Description

Electrode and lithium ion secondary battery Technical Field The present invention relates to an electrode and a lithium ion secondary battery. The present application claims priority based on japanese patent application No. 2023-180185 filed on 10/19 in 2023 and incorporated herein by reference. Background Lithium ion secondary batteries are also widely used as power sources for mobile devices such as mobile phones and notebook computers, hybrid vehicles, and the like. The lithium ion secondary battery has a power generating element and an exterior body accommodating the power generating element. If an impact is applied to the lithium ion secondary battery, the power generating element contacts the exterior body, and the positive electrode active material or the negative electrode active material may come off from the power generating element. The positive electrode active material and the negative electrode active material that have fallen off do not participate in the battery reaction. Therefore, the falling-off of the positive electrode active material and the negative electrode active material may cause a decrease in the performance of the lithium ion secondary battery. For example, patent document 1 discloses a lithium ion secondary battery in which corners of electrodes are chamfered. By chamfering the corners of the electrodes, the positive electrode active material and the negative electrode active material can be prevented from falling off. Prior art literature Patent literature Patent document 1 International publication No. 2022/176892 Disclosure of Invention Technical problem to be solved by the invention As described in patent document 1, if the corners of the electrodes are chamfered, the capacity of the lithium ion secondary battery becomes small accordingly. The present disclosure has been made in view of the above-described problems, and an object thereof is to provide an electrode and a lithium ion secondary battery which prevent an active material layer from falling off due to stress concentration and have a large capacity. Means for solving the technical problems In order to solve the above problems, the present invention provides the following means. (1) The electrode according to the first aspect includes a current collector and an active material layer in contact with one surface of the current collector. The active material layer has a main portion and a sub portion when viewed from the lamination direction. The auxiliary portion is separated from the main portion and is located at an outer peripheral end portion of the active material layer. The area of the main portion is larger than the area of the auxiliary portion. (2) In the electrode according to the above aspect (1), the sub-portion may be located at an outer peripheral corner of the active material layer. (3) In the electrode according to the above-described embodiment (1) or (2), the active material layer may have a plurality of the sub-portions. (4) The electrode according to any one of the above aspects (1) to (3), wherein the area of the main portion is 55% or more and 88% or less of the total area of the active material layer. (5) In the electrode according to any one of the above aspects (1) to (4), the side of the main portion facing the sub portion may have irregularities when viewed from the stacking direction. (6) The electrode according to any one of the above aspects (1) to (5), wherein the active material contained in the active material layer may be lithium titanate. (7) The electrode according to any one of the above aspects (1) to (5), wherein the active material contained in the active material layer may be lithium cobaltate. (8) The lithium ion secondary battery according to the second aspect includes the electrode and the electrolyte according to any one of the above aspects (1) to (7). Effects of the invention The electrode and the lithium ion secondary battery according to the above embodiments prevent the active material layer from falling off due to stress concentration, and have a large capacity. Drawings Fig. 1 is a schematic cross-sectional view of a lithium ion secondary battery according to a first embodiment. Fig. 2 is a plan view of the positive electrode according to the first embodiment. Fig. 3 is a plan view of the negative electrode according to the first embodiment. Fig. 4 is a top view of the positive electrode according to the first modification. Symbol description A separator 20. Positive electrode 22. The positive electrode current collector 24. The positive electrode active material layer 25. Main part 26. A.c. Auxiliary part A negative electrode 32. The negative electrode current collector A negative electrode. Active material layer 40. A.50. Outer package Metal foil 54. 60. 62.. Terminals A lithium ion secondary battery Detailed Description The embodiments will be described in detail with reference to the drawings. In the drawings used in the following description, for ease of unders