Polymer composite membrane, method for preparing same and lithium ion battery

A polymer and composite membrane technology, applied in the field of lithium-ion batteries, can solve the problems of reduced bonding performance, low safety performance, thermal failure of the diaphragm, etc., to avoid the thermal runaway of the diaphragm, reduce the reaction heat release, and slow down the effect of the reaction

Active Publication Date: 2018-07-10
BYD CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, in the foregoing technical solutions, there is a large contradiction between the adhesion between the organic/inorganic composite layer and the porous base layer and the air permeability of the composite membrane.
This is because this organic/inorganic composite layer is formed by coating and relies on the gaps of inorganic particles to form voids. If you want to increase the porosity (permeability) of the organic/inorganic composite layer, you need to reduce the polymer bonding. However, due to the high glass transition temperature of the aforementioned polymer binder, its viscosity is not good. Once the amount of polymer binder is reduced, it will lead to poor bonding performance between the coating and the base layer. reduced, which in turn makes the high temperature thermal stability of this composite film worse
[0005] In addition, since the melting temperature of the high-temperature closed-cell material and th

Method used

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  • Polymer composite membrane, method for preparing same and lithium ion battery
  • Polymer composite membrane, method for preparing same and lithium ion battery
  • Polymer composite membrane, method for preparing same and lithium ion battery

Examples

Experimental program
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Example Embodiment

[0051] At the same time, according to the second aspect of the present invention, a method for preparing a polymer composite film is provided, characterized in that the preparation method includes the following steps: S1, providing a polymer base film; S2, using a first resistant The spinning solution of the thermal polymer material and / or the spinning solution of the second heat-resistant polymer material is formed on at least one side surface of the polymer base film by electrospinning to form multiple sub-heat-resistant layers arranged in sequence The precursor is dried to remove the solvent to obtain a heat-resistant layer comprising multiple sub-heat-resistant layers, wherein the melting point of the first heat-resistant polymer material is not less than 200°C; the melting point of the second heat-resistant polymer material is not less than 100°C; the closed cell temperature of each sub-heat-resistant layer increases sequentially along the direction from the inside to the ...

Example Embodiment

[0095] Embodiment 1 (preparation of two-layer polymer composite film of PE base film-heat-resistant layer)

[0096] This example is used to illustrate the polymer composite membrane provided by the present invention and its preparation method.

[0097] (1) Forming a heat-resistant layer (including 6 layers of sub-heat-resistant layers with different materials)

[0098] Add the spinning polymer (see Table 2 for specific raw materials) and optional solubilizers into N,N-dimethylacetamide (DMAc) (commercially purchased from Aladdin Reagent Company, the same below), in a water bath at 70°C Under magnetic stirring, it is fully dissolved to form a spinning solution A-F with a polymer (aforesaid AS) concentration of 15% by weight;

[0099] Table 2

[0100]

[0101] One side surface of the 11 μm PE base film (purchased from Japan SK Company, the brand is BD1201, the same below) is wrapped on the roller (collecting device), and the other side surface of the PE base film is electro...

Example Embodiment

[0108] Embodiment 2 (preparation of three-layer polymer composite film of heat-resistant layer-PE base film-heat-resistant layer)

[0109] This example is used to illustrate the polymer composite membrane provided by the present invention and its preparation method.

[0110] (1) Form the heat-resistant layer: adopt the method in embodiment 1 to form the first heat-resistant layer (thickness is 3 μ m, porosity 85%) at one side of PE base film earlier (the described first heat-resistant layer comprises PE On the surface of the base film, six sub-heat-resistant layers are sequentially formed, which are sub-heat-resistant layer A (thickness 0.5 μm, closed cell temperature 123 °C), sub-heat-resistant layer B (thickness 0.5 μm, closed cell temperature 132 °C) , sub-heat-resistant layer C (thickness 0.5 μm, closed cell temperature 140 ° C), sub-heat-resistant layer D (thickness 0.5 μm, closed cell temperature 176 ° C), sub-heat-resistant layer E (thickness 0.5 μm, closed cell tempera...

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Abstract

The invention discloses a polymer composite membrane, a method for preparing the same and a lithium ion battery with the polymer composite membrane. The polymer composite membrane comprises a porous basement membrane and heat-resistant layers. The heat-resistant layers cover at least one side surface of the porous basement membrane and comprise a plurality of heat-resistant sub-layers, the heat-resistant sub-layers are sequentially arranged in a stacked manner, and pore closing temperatures of the various heat-resistant sub-layers are sequentially increased from the inside to the outside; thevarious heat-resistant sub-layers comprise first heat-resistant polymer materials and/or second heat-resistant polymer materials and are independently of fiber network structures; the melting points of the first heat-resistant polymer materials are not lower than 200 DEG C; the melting points of the second heat-resistant polymer materials are not lower than 100 DEG C. The polymer composite membrane, the method and the lithium ion battery have the advantages that the multiple heat-resistant sub-layers with the sequentially increased pore closing temperatures are formed and can be softened in different temperature ranges, accordingly, the polymer composite membrane has dynamic (phased) pore closing behavior to adapt to internal excessive heating of the battery, diaphragm thermal runaway dueto pore breaking phenomena can be effectively prevented, and the battery is safe at the high temperatures.

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. The performance of the separator 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. A separator w...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/417H01M50/42H01M50/423H01M50/434H01M50/449H01M50/451H01M50/454H01M50/457H01M50/491
CPCH01M10/0525H01M50/44H01M50/403H01M50/451H01M50/491H01M50/42H01M50/423H01M50/417H01M50/434H01M50/454H01M50/457B01D69/12B01D69/02B01D2325/22B01D2325/32B01D2323/39B01D67/0004B01D71/28B01D71/42B01D71/56B01D71/64B01D71/76B01D71/34B01D71/32B01D71/40B01D71/62H01M10/4235Y02E60/10B01D69/14B01D2323/28B01D2325/02B01D2325/04
Inventor 胡家玲单军何龙
Owner BYD CO LTD
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