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Diaphragm and preparation method thereof as well as lithium ion battery

A separator and composite film technology, applied in secondary batteries, battery pack components, circuits, etc., can solve the problem that batteries cannot achieve high-rate discharge, and achieve good high-rate discharge characteristics, good liquid absorption, and good high temperature resistance. sexual effect

Inactive Publication Date: 2009-07-01
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problem that batteries with traditional separators cannot achieve high rate discharge

Method used

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  • Diaphragm and preparation method thereof as well as lithium ion battery
  • Diaphragm and preparation method thereof as well as lithium ion battery
  • Diaphragm and preparation method thereof as well as lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0026] In the preparation method of the above diaphragm, the organic polymer film-forming material is dissolved in an organic solvent to form a transparent solution, and the solution is coated on the surface of the substrate and dried to prepare the diaphragm.

[0027] The coating adopts coating methods known to those skilled in the art, such as printing, rolling, squeegeeing, dipping, spraying and pulling.

[0028] At the same time, the present invention also provides a lithium ion battery containing the above separator, including a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode, the separator and the negative electrode are made into cells by techniques known to those skilled in the art, such as winding or stacking in sequence. Put the cell into the battery casing, inject the electrolyte, and seal the battery to obtain the battery. The electrolyte is an electrolyte known to those skilled in the art; the battery casing is a ca...

Embodiment 1

[0032] (1) Preparation of diaphragm

[0033]Take 2g of PVDF powder, among them, the selected PVDF has a heat-resistant temperature of 170°C and a heat shrinkage rate of 3%, dissolve it in 40g of organic solvent, add 1.5g of plasticizer, and stir at a temperature of 50°C until the powder is completely Dissolve to obtain a colorless and transparent solution, apply the solution on both sides of the PET film by dipping, dry to form a film, and the film thickness is controlled at 2 μm.

[0034] (2) Preparation of battery

[0035] (a) Preparation of positive electrode

[0036] Dissolve 30 grams of polyvinylidene fluoride (PVDF) in 450 grams of N-methylpyrrolidone (NMP) solvent to prepare a binder solution, and then mix 940 grams of LiCoO 2 Add 30 grams of acetylene black powder into the above solution, stir and mix evenly to obtain a positive electrode slurry; use a pulper to evenly coat the positive electrode slurry on both sides of an aluminum foil with a thickness of 18 microns...

Embodiment 2

[0043] A PET composite separator was prepared according to the method of Example 1, except that no plasticizer was added.

[0044] The SL6043122 soft package battery was fabricated according to the method of Example 1, except that the battery separator used was the separator of Example 2.

[0045] Prepare 50 PCS of SL6043122 flexible packaging battery according to the above method.

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Abstract

A diaphragm is selected from a composite membrane containing polyethylene terephthalate membrane as the base material. The composite membrane contains at least one organic polymer membrane consisting of polymer film-forming materials with a thermal resistant temperature of 170 DEG C to 500 DEG C and heat shrinkage of 0% to 5%. Preferably, a plasticizer is added during solution preparation to achieve more uniform pore distribution so as to obtain the composite membrane with excellent performance. The diaphragm has high temperature resistance and high safety when used for battery diaphragm. In addition, the diaphragm has good solution adsorption performance, so that the diaphragm can adsorb the electrolyte to improve the circle performance of the battery. The invention also provides the diaphragm preparation method, which is simple and convenient. Compared with the conventional battery and the battery using PET composite diaphragm with inorganic coating, the battery using the diaphragm has higher capacity, better high-rate discharge characteristics and low-temperature discharger performance, no flame and liquid leakage during high-temperature test, and excellent high-temperature safety performance.

Description

【Technical field】 [0001] The invention relates to a diaphragm, a preparation method thereof and a lithium ion battery. 【Background technique】 [0002] Separators are a key component of lithium-ion batteries. Separators for Li-ion batteries are usually thin porous insulating materials with high ion permeability, good mechanical strength, and long-term stability to various chemicals and chemical solvents. When a large current is generated inside the battery due to an external short circuit or wrong connection, and the internal temperature of the battery rises to the closed cell temperature of the diaphragm, the diaphragm will be thermally melted and the micropore structure will be closed, thereby cutting off the current and ensuring the safety of the battery. The performance of the separator determines the interface structure and internal resistance of the battery, which in turn affects the key characteristics of the battery such as capacity, cycle, charge and discharge curre...

Claims

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Application Information

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IPC IPC(8): H01M2/16C08J5/22H01M10/40H01M50/403H01M50/411H01M50/417H01M50/42H01M50/426H01M50/491
CPCY02E60/12H01M2/1653H01M2/162Y02E60/10H01M50/44H01M50/417H01M50/42H01M50/426
Inventor 武汉辉梁世硕
Owner BYD CO LTD
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