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

A battery diaphragm and secondary battery technology, applied in the field of lithium-ion secondary batteries, can solve the problems of low safety of battery diaphragm, poor battery cycle performance, etc., easy to achieve industrial implementation conditions, reduce internal resistance of the diaphragm, and ensure cycle performance Effect

Active Publication Date: 2012-10-17
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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Effect test

preparation example Construction

[0024] The preparation method of the composition for battery separator of the present invention includes mixing the modified polysiloxane shown in Formula 1 and the inorganic filler in a solvent, and stirring 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 the separator on both sides of the porous polyolefin membrane and curing it, characterized in that the composition for the separator is the composition for the battery separator provided by the present invention .

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

[0027] In the present invention, the battery separator can be obt...

Embodiment 1

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

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

[0044] (3) Using the dip coating method, coat the membrane slurry obtained in step (2) on both sides of the PE film (thickness 18μm, porosity 45%) with a coating thickness of 3μm; place it under a 100W high-pressure mercury lamp to Irradiate with ultraviolet light with a wavelength of 365nm, the irradiation distance is 10cm, and the irradiation time is 10min.

[0045] Through the above steps, the battery separator of this embodiment is o...

Embodiment 2-5

[0047] The battery separators of Examples 2-5 were prepared using the same steps as Example 1, 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 present invention relates to the field of lithium ion secondary batteries, in particular to a composition for battery diaphragms, a battery diaphragm 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. As people's demands continue to increase, 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 current lithium-ion battery separators are mainly polyolefin separators, and the battery has internal short-circuits. At this time, a large amount of local heat will cause the polyolefin diaphragm to heat sh...

Claims

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Application Information

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