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Positive electrode for lithium ion secondary cell, and lithium ion secondary cell

A secondary battery and lithium-ion technology, which is applied in the field of current collectors for lithium-ion secondary batteries and positive electrodes for lithium-ion secondary batteries, can solve problems such as unclear relationship between electrodes, and achieve good high-current characteristics and high durability sexual effect

Inactive Publication Date: 2019-11-15
SHOWA DENKO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the relationship between the porosity of the electrode and the lifetime characteristics is not clear.

Method used

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  • Positive electrode for lithium ion secondary cell, and lithium ion secondary cell
  • Positive electrode for lithium ion secondary cell, and lithium ion secondary cell

Examples

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Comparison scheme
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Embodiment

[0121] Hereinafter, examples of the present invention are shown, and the present invention will be described more specifically. In addition, these examples are simply illustrations for explanation, and the present invention is not limited by them at all.

[0122] [Manufacture and evaluation of current collectors for positive electrodes and positive electrodes]

manufacture example 1

[0124]

[0125] The number-average particle size of acetylene black HS-100 (manufactured by DENKA Co., Ltd., DENKA BLACK (registered trademark), pressed product, and primary particle (hereinafter sometimes simply referred to as primary particle size) as a powdery conductive material: 48 nm ) 3.5 parts by mass, glycerolated chitosan (manufactured by Dainichi Seika Co., Ltd., deacetylation degree: 86mol%, weight average molecular weight: 8.6×10 4 ) 2.5 parts by mass, 2.5 parts by mass of anhydrous pyromellitic acid as an organic acid, and 160 parts by mass of N-methyl-2-pyrrolidone (special grade reagent) were mixed.

[0126] The above material was processed at 300 rpm for 10 minutes using a dissolving and stirring type disperser (produced by Hideo Seiki Co., Ltd., DISPERMAT CV3), and then processed at 20,000 rpm for 30 seconds using a homogenizer (manufactured by Iada Trading Co., Ltd., PRO200) , and a coating liquid in which acetylene black was sufficiently dispersed was obt...

manufacture example 2

[0139] A positive electrode was produced in the same manner as in Production Example 1 except that the acetylene black HS-100 in Production Example 1 was changed to acetylene black powder (manufactured by DENKA Co., Ltd., DENKABLACK (registered trademark), powdery product, primary particle size: 35 nm). The current collector was used to evaluate the coating amount of the coating layer and the difference (Ra1-Ra2) of the surface roughness. An unpressed positive electrode 2 was produced, and the volume resistivity of the positive electrode active material layer and the penetration resistance of the positive electrode were evaluated. Table 1 shows the evaluation results.

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Abstract

[Problem] To provide an electrode for a lithium ion secondary cell that has both excellent high-current properties and high durability even when the void fraction of the electrode is sufficiently increased, and a lithium ion secondary cell. [Solution] A positive electrode for a lithium ion secondary cell, the positive electrode including a current collector in which a covering layer is formed on one or both surfaces of a sheet-shaped electrically conductive substrate, and a positive electrode active material layer formed on the covering layer, wherein the positive electrode is characterized inthat: the covering layer contains a granular electrically conductive material and a first binder; the positive electrode active material layer contains a positive electrode active material, a conductivity auxiliary agent, and a second binder; the void fraction of the positive electrode active material layer is 43-64%; and the difference (Ra1-Ra2) between the surface roughness Ra1 of the coveringlayer and the surface roughness Ra2 of the electrically conductive substrate surface covered by the covering layer is 0.10-0.40 microns.

Description

technical field [0001] The present invention relates to a current collector for lithium ion secondary batteries and a positive electrode for lithium ion secondary batteries using the current collector. More specifically, the present invention relates to a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery capable of achieving both high large current characteristics and high durability. Background technique [0002] In recent years, secondary batteries suitable for applications requiring high output power, such as hybrid vehicles, electric tools, and drones, have been demanded, and among them, lithium-ion secondary batteries have become mainstream. Especially in power tools and unmanned aerial vehicles, since they are used repeatedly from full charge to full discharge, it is required to be able to use a large current for a long time, and even if it is used for a long time, there is little deterioration. [0003] However, in the case of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/64H01M4/66
CPCY02E60/10H01M2004/028H01M2004/021H01M4/366H01M4/624H01M4/622H01M4/13H01M4/621H01M10/052H01M4/803H01M10/0525
Inventor 中村武志
Owner SHOWA DENKO KK
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