Polymer composite membrane as well as preparation method and lithium ion battery with same

A polymer and composite film technology, applied in the field of lithium-ion batteries, can solve the problems of poor high temperature resistance, poor mechanical strength of materials, and high cost, to ensure high temperature resistance safety performance, avoid contact between positive and negative electrodes, improve The effect of high temperature resistance

Inactive Publication Date: 2018-03-09
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, although the separator prepared by the "melt stretching method" is relatively low in cost and relatively good in mechanical strength (toughness and strength), its high temperature resistance stability (thermal shrinkage) is not good; Although the high-temperature stability of the separator prepared by the method has been improved, its cost is relatively high, and the mechanical strength of the material is deteriorated (hardened), which limits its development in the battery field.

Method used

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  • Polymer composite membrane as well as preparation method and lithium ion battery with same

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preparation example Construction

[0039] The preparation method of the ceramic diaphragm provided by the present invention realizes optimal dispersion of ceramic particles by controlling the amount of each component in the ceramic layer slurry, the number average molecular weight of the dispersant, and the rotational speed of the ceramic layer slurry, thereby controlling the packing density between the ceramic particles To control the surface density of the ceramic layer at a unit thickness (1μm) to 1.8mg / cm 2 2 In this way, the high temperature heat shrinkability of the ceramic diaphragm can be improved on the basis of basically not reducing the gas permeability, so that the heat resistance temperature can reach above 160°C, that is, the thermal stability can be improved without increasing the thickness of the ceramic layer, so that Does not affect the energy density of the battery.

[0040] According to the polymer composite membrane of the present invention, preferably, in the ceramic layer, relative to 100...

Embodiment approach

[0050] According to the polymer composite film of the present invention, the acrylate cross-linked polymer refers to a polymer obtained by cross-linking polymerization of reactive acrylate monomers. The cross-linking degree of the acrylate cross-linked polymer may be 2-30%, preferably 5-20%. In the present invention, the degree of crosslinking refers to the percentage of the weight of the crosslinked polymer to the total weight of the polymer. In addition, the glass transition temperature of the acrylate crosslinked polymer is preferably -20°C to 60°C, more preferably -12°C to 54°C. According to a preferred embodiment of the present invention, the acrylate crosslinked polymer is the second acrylate crosslinked polymer, the third acrylate crosslinked polymer, or the first acrylate crosslinked polymer A mixture with the second acrylate crosslinked polymer and / or the third acrylate crosslinked polymer; wherein, the first acrylate crosslinked polymer contains 70 to 80% by weight ...

Embodiment 1

[0149] Embodiment 1 (preparation of the polymer composite film of PE base film-heat-resistant fiber layer two-layer structure)

[0150] This example is used to illustrate the polymer composite membrane provided by the present invention and its preparation method.

[0151] (1) Form a heat-resistant fiber layer on the PE base film:

[0152] Polyetherimide (ultem 1000 commercially available from SABIC Innovative Plastics (Shanghai) Co., Ltd., with a melting point of 370-410°C and a glass transition temperature of 215°C, the same below) and polyvinylidene fluoride-hexafluoropropylene (commercially purchased from Akema Investment Co., Ltd., the weight average molecular weight is 450000g / mol, the melting point is 152°C, the glass transition temperature is -40°C, and the liquid absorption rate in the electrolyte solution at 25°C is 45%, the same below ) according to the weight ratio of 1:1, the blending method adopts mechanical stirring to stir the two polymers evenly, the stirring ...

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Abstract

The invention relates to the field of lithium ion batteries, discloses a polymer composite membrane as well as a preparation method thereof, and further discloses a lithium ion battery with the polymer composite membrane. The polymer composite membrane comprises a porous base membrane and a thermal-resistant fiber layer, wherein the surface of at least one side of the porous base membrane is covered with the thermal-resistant fiber layer; the thermal-resistant fiber layer is made of a material containing a first high polymer material and a second high polymer material simultaneously; the firsthigh polymer material is a thermal-resistant high polymer material of which the melting point is 180 DEG C or greater; the melting point of the second high polymer material is lower than that of thefirst high polymer material; the liquid absorption capacity of the second high polymer material in electrolyte of 25 DEG C is 40% or greater, with the error of + / -5%. Due to adoption of the first highpolymer material and the second high polymer material, the high temperature stability and the mechanical properties of the polymer composite membrane under high temperature conditions can be improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a polymer composite membrane and a preparation method thereof; the invention also includes a lithium ion battery using the aforementioned polymer composite membrane. Background technique [0002] Lithium-ion batteries are mainly composed of positive / negative electrode materials, electrolytes, separators and battery casing packaging materials. The separator is an important part of the lithium-ion battery, which is used to separate the positive and negative electrodes and prevent the internal short circuit of the battery; it allows the electrolyte ions to pass freely to complete the electrochemical charge and discharge process. Its performance determines the interface structure and internal resistance of the battery, which directly affects the rate performance, cycle performance and safety performance (high temperature resistance) of the battery. The separator with excellent pe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/414H01M50/417H01M50/42H01M50/423H01M50/426H01M50/434H01M50/44H01M50/449H01M50/451H01M50/454H01M50/457H01M50/491
CPCH01M10/0525H01M50/44H01M50/403H01M50/423H01M50/414H01M50/417H01M50/434H01M50/451H01M50/491H01M50/42H01M50/426H01M50/457H01M50/454H01M10/052H01M50/461H01M10/4235H01M50/446H01M50/443H01M50/489H01M50/449H01M50/463H01M50/46Y02E60/10Y02P70/50
Inventor 胡家玲单军吴金祥何龙
Owner BYD CO LTD
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