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Vinyl fluoride-based copolymer binder for battery electrodes

A technology based on fluorine-based copolymers and vinyl fluoride, which can be used in battery electrodes, circuits, electrical components, etc., and can solve problems such as resin hardness

Inactive Publication Date: 2008-09-10
EI DU PONT DE NEMOURS & CO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But in this case, too, there is the fundamental problem of resin hardness due to the hardness of PVDF-acrylate

Method used

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  • Vinyl fluoride-based copolymer binder for battery electrodes
  • Vinyl fluoride-based copolymer binder for battery electrodes
  • Vinyl fluoride-based copolymer binder for battery electrodes

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1 to 5

[0032] Examples 1 to 5, Comparative Example 1

[0033] Bond Strength Evaluation Test

[0034] After the organosol of the resin was prepared by mixing 5wt% of the vinyl fluoride-based copolymer or PVDF powder shown in Table 1 with an organic solvent, 5wt% of ketjen black was mixed to form a paste. The paste was coated on the frosted surface of aluminum foil (5cm×10cm) with a thickness of 15 μm, the coated surface of the aluminum foil was clamped to another aluminum foil of the same size, and the coated paste was spread by hand through a film applicator. Expand. The thickness of the sample was 120 μm. The smears were dried in a vacuum desiccator (LCV-232 from Tabai Espec) at 190°C for 3 hours. Afterwards, test samples of 1 cm x 5 cm were cut and used for testing of bond strength.

[0035] Bond strength was determined by a peel strength test in a 180 degree direction. The results are listed in Table 1. The bond strength of the tested samples was compared with samples prep...

Embodiment 9 to 10， comparative example 2 to 3

[0045] Electrochemical test:

[0046] The paste for the bond strength test was coated on one side of an aluminum foil (0.5 cm×5 cm) with a thickness of 15 μm and dried at 190° C. for 3 hours. This sample was used as a test electrode, and the stability of the electrode was determined by cyclic voltammetry. The results are listed in Table 3.

[0047] A comparison of the current values ​​at 3.50 V in each cycle shows that there is a decrease in current both in the examples and in the comparative examples. The reason for this phenomenon is assumed to be the LiPF in the electrolyte solution 6 Fluorination of aluminum foil forms an inactive film with low electrical conductivity, resulting in increased electrical resistance. However, there were significant differences in this propensity for reduction. For PVDF, the current decreases to about 30% in the second cycle, then decreases continuously to a few percent and becomes practically zero after 121 cycles. However, for the ele...

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Abstract

A binder for a battery electrode comprising a vinyl fluoride-based copolymer. The vinyl fluoride-based copolymer preferably comprises about 25 to about 85 mol% vinyl fluoride and about 75 to about 15 mol% of at least one other fluorine-containing monomer. In a preferred embodiment, the binder comprises a mixture of at least two types of vinyl fluoride-based copolymers. In another embodiment the binder comprises a vinyl fluoride-based copolymer and at least one other fluorine-based polymer. The binder can be dispersed in water or organic solvent to form a paste for binding electrode materials to current collectors for battery electrode fabrication. Battery electrodes with improved adhesion strength and electrochemical stability result.

Description

field of invention [0001] This invention relates to improved fluoropolymer binders for binding electrode materials in the manufacture of battery electrodes. Background of the invention [0002] In Li-ion batteries, binders are required to keep the conduction of ions and electrons in the electrodes stable. Currently, polyvinylidene fluoride (PVDF) is the typical binder used for this purpose. But in the case of PVDF, delamination of the active material (ie, electrode material, such as lithium composite oxide or carbon) occurs due to insufficient bond strength and flexibility, thus requiring the development of new binders for electrodes. [0003] In recent years, along with the development of microelectronic devices such as cellular phones and cameras, tiny, optical and high-output power sources have been actively developed. Lithium-ion secondary batteries are widely used as batteries meeting these needs. [0004] In lithium-ion batteries, the anode uses aluminum foil as the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F214/20C08L27/14H01M4/62H01M4/139
CPCH01M4/622C08L2205/02C08F214/20C08L27/16H01M4/621C08L27/14H01M4/623C09D127/16Y02E60/10C08L2666/04H01M4/62
Inventor J·王S·莫奇祖基R·E·乌肖尔德
Owner EI DU PONT DE NEMOURS & CO
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