Composition for battery diaphragm, battery diaphragm and lithium-ion secondary battery

A battery separator and secondary battery technology, applied in the field of lithium ion secondary batteries, can solve the problems of poor battery cycle performance and low safety of battery separators, and achieve the advantages of reducing internal resistance of the separator, easy industrial implementation conditions, and ensuring cycle performance. Effect

Active Publication Date: 2011-10-05
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The invention solves the technical problems of low battery separator safety and poor battery cycle performance existing in the prior art

Method used

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  • Composition for battery diaphragm, battery diaphragm and lithium-ion secondary battery
  • Composition for battery diaphragm, battery diaphragm and lithium-ion secondary battery
  • Composition for battery diaphragm, battery diaphragm and lithium-ion secondary battery

Examples

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preparation example Construction

[0024] The preparation method of the composition for a battery separator of the present invention comprises mixing the modified polysiloxane shown in Formula 1 and an inorganic filler in a solvent, stirring uniformly and ball milling to a desired particle size.

[0025] The present invention also provides a battery separator, which is obtained by coating the composition for separator on both sides of a porous polyolefin film and curing it, characterized in that the composition for separator is the composition for battery separator provided by the present invention .

[0026] The porous polyolefin film is a variety of polyolefins that are commonly used as battery separators, such as polypropylene (PP), polyethylene terephthalate (PET) or polyethylene (PE), which are common to those skilled in the art. The pore diameter of the porous polyolefin membrane is 50-300nm, the porosity is 15-50%, and the thickness is 10-40μm.

[0027] In the present invention, the battery separator ca...

Embodiment 1

[0042] (1) Preparation of modified polysiloxane: The modified polysiloxane shown in Formula 1 of this example was prepared by using the method disclosed in the example of US2005271948A1, wherein n is 60, m is 50, and x is 3.

[0043] (2) Dissolve the modified polysiloxane prepared in step (1) into THF to form a 2.5wt% solution; add BaTiO 3 , BaTiO 3 The weight ratio to the modified polysiloxane is 10:1; after mixing evenly, transfer to a ball mill for ball milling until BaTiO 3 The average particle diameter was 400 nm, and a separator slurry was obtained.

[0044] (3) Adopting the dipping coating method, coat the separator slurry obtained in step (2) on both sides of the PE film (thickness 18 μm, porosity 45%), and the coating thickness is 3 μm; placed under a 100W high-pressure mercury lamp, with Ultraviolet light with a wavelength of 365nm is irradiated, the irradiation distance is 10cm, and the irradiation time is 10min.

[0045] Through the above steps, the battery sepa...

Embodiment 2-5

[0047] The same steps as in Example 1 were used to prepare the battery separators of Examples 2-5, except that the components and contents of the separator composition are shown in Table 1 below:

[0048] Table 1

[0049]

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Abstract

The invention provides a composition for a battery diaphragm, containing modified polysiloxane, a solvent and an inorganic filler, wherein the modified polysiloxane has a structure shown as a formula 1. The invention also provides a battery diaphragm prepared from the composition and a lithium-ion secondary battery containing the battery diaphragm. The composition for the battery diaphragm provided by the invention contains the modified polysiloxane shown as the formula 1, the main chain segment of the modified polysiloxane is an inorganic silica chain segment, and the modified polysiloxane has favorable compatibility with the inorganic filler so that anode and cathode circuit breaking can be still ensured when a porous polyolefin film shrinks due to overhigh temperature and the safety performance of the battery is improved; in addition, a lateral group ethyoxyl repeating unit of the modified polysiloxane can enhance the affinity of lithium ions and reduce the internal resistance of the diaphragm, and a lateral group cinnamoyl group can be cured and crosslinked without any initiator or being heated, thus the cycle performance of the battery is ensured effectively.

Description

technical field [0001] The invention relates to the field of lithium ion secondary batteries, in particular to a composition for a battery separator, a battery separator and a lithium ion secondary battery. Background technique [0002] Lithium-ion secondary batteries have the characteristics of high energy density, high voltage, no pollution, no metal lithium, high cycle life, no memory effect, and fast charging speed. With the continuous improvement of people's needs, lithium-ion secondary batteries are required to have higher capacity and higher performance. [0003] In lithium-ion secondary batteries, as the battery capacity and discharge rate increase, dendrites are likely to be generated during the cycle, piercing the separator and causing a short circuit; in addition, the currently used lithium-ion battery separators are mainly polyolefin separators, and internal short circuits occur in the battery. When a large amount of local heat is generated, the polyolefin separ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L83/12C08K3/22C08K3/34C08K3/26C08K3/30C08K3/24H01M2/16H01M10/0525
CPCY02E60/122Y02E60/12Y02E60/10
Inventor 鲁遥
Owner BYD CO LTD
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