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Flame-retardant composite diaphragm, preparation method thereof and lithium ion battery

A flame-retardant composite and diaphragm technology, applied in the field of lithium-ion batteries, can solve the problems of restricting rapid development, affecting the electrochemical performance of lithium-ion batteries, breaking through, etc.

Active Publication Date: 2021-07-06
HAIKE GRP RES INST OF INNOVATION & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

(3) The overall thermal runaway of the battery. At this stage, as the internal pressure of the lithium-ion battery rises sharply, the outer packaging of the battery is broken, and the external oxygen, electrolyte vapor, and flammable fumes / flammable fumes generated by various reactions burn. reaction, and then burn and catch fire, resulting in the overall thermal runaway of the lithium-ion battery
However, in the actual application process, flame retardant additives are directly added to the electrolyte, which will seriously affect the electrochemical performance of lithium-ion batteries.
The use of thermally closed-cell separators or functional coating separators can improve the safety performance of lithium-ion batteries to a large extent, and has little impact on the electrochemical performance of the battery during normal operation, but it still cannot fundamentally control the thermal runaway rate of the battery.
[0005] Therefore, how to find a suitable method that can solve the above-mentioned problems existing in the existing diaphragm, and realize the effective management and control of the safety performance of the lithium-ion battery under the premise of ensuring that the comprehensive performance of the product is not affected, has become a limit to its rapid development. The key issue of development is also one of the key technical issues to be solved urgently in the industry

Method used

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  • Flame-retardant composite diaphragm, preparation method thereof and lithium ion battery
  • Flame-retardant composite diaphragm, preparation method thereof and lithium ion battery
  • Flame-retardant composite diaphragm, preparation method thereof and lithium ion battery

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preparation example Construction

[0084] The present invention also provides a preparation method of flame retardant microcapsules, comprising the following steps:

[0085] 1) Under the condition of protective gas, after dispersing the emulsifier and water, an emulsion is obtained;

[0086] 2) Under the condition of protective gas, add the monomer and cross-linking agent of the inner wall material to the emulsion obtained in the above steps for initial emulsification, then add the core material and initiator for re-emulsification, and finally Carry out heating reaction, obtain monolayer microcapsule;

[0087] 3) After mixing the single-layer microcapsules obtained in the above steps and the molten liquid of the outer capsule wall material, spray drying to obtain flame-retardant microcapsules.

[0088] The parameters, selections, and corresponding optimization principles of raw materials and products in the above-mentioned preparation method in the present invention can correspond to the parameters, selections...

Embodiment 1

[0154] (1) Preparation of double-layer flame retardant microcapsules:

[0155] A. Add 30ml methyl methacrylate to the emulsion containing 2.5g Triton X-100, emulsify and disperse evenly under nitrogen atmosphere, add ethylene glycol dimethacrylate and stir for 30min, add 30ml tribromomethyl phosphoric acid The ester and 0.2 g of azobisisoheptanonitrile were reacted at 45° C. for 5 h, and sodium chloride was added to terminate the reaction, washed and dried to obtain polymethyl methacrylate-coated microcapsules of tribromomethyl phosphate.

[0156] B. Add the microcapsules prepared in A to polyethylene melt, and spray-dry at 50° C. to obtain polyethylene-coated double-layer flame-retardant microcapsules.

[0157] (2) Preparation of flame retardant diaphragm

[0158] A. Mix double-layer flame-retardant microcapsules with a mass ratio of 25:6:0.5:3.5:65, polyacrylic acid, ethylene glycol, fatty alcohol polyoxyethylene ether, and deionized water, and stir at high speed to obtain ...

Embodiment 2

[0177] (1) The preparation process of the double-layer flame-retardant microcapsules is the same as in Example 1.

[0178] (2) Preparation of flame retardant diaphragm:

[0179] A. Mix double-layer flame-retardant microcapsules with a mass ratio of 25:6:0.5:3.5:65, polyacrylic acid, ethylene glycol, fatty alcohol polyoxyethylene ether, and deionized water, and stir at high speed to obtain a double-layer flame-retardant microcapsule. capsule slurry;

[0180] B. Apply the double-layer flame-retardant microcapsule slurry to the side of the PP diaphragm (thickness 9 μm, porosity 45%) by spray coating, and the median thickness of the coating is 6 μm to obtain a flame-retardant diaphragm;

[0181] (3) The preparation process of the lithium-ion battery is the same as in Example 1.

[0182] The lithium-ion battery prepared in Example 2 of the present invention was tested for cycle performance, gas permeability and acupuncture performance.

[0183] Cycle performance test: the number...

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Abstract

The invention provides a flame-retardant composite diaphragm. The flame-retardant composite diaphragm comprises a base diaphragm; a flame-retardant coating is compounded on at least one surface of the base diaphragm; the flame-retardant coating comprises a double-layer flame-retardant microcapsule. According to the composite diaphragm provided by the invention, the functional coating of the composite diaphragm is a flame-retardant coating with double layers of flame-retardant microcapsules, so the safety problems such as combustion or explosion caused by thermal runaway of a battery can be effectively prevented. And the flame retardant is prevented from being in direct contact with the electrolyte, so that the electrochemical performance is not influenced. Meanwhile, according to the flame-retardant lithium ion battery diaphragm, the thermal shrinkage of the base diaphragm can be reduced. When the base diaphragm of the lithium ion battery diaphragm is heated, the diaphragm can be prevented from shrinking. In addition, the flame-retardant lithium ion battery composite diaphragm provided by the invention is simple in preparation process, controllable in condition and relatively low in cost, can effectively improve the safety performance of the battery, and has wide practical value in the application field of the lithium ion battery.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery diaphragm materials, and relates to a flame-retardant composite diaphragm and a preparation method thereof, and a lithium-ion battery, in particular to a composite diaphragm containing a double-layer flame-retardant microcapsule functional coating and a preparation method thereof, lithium ion battery ion battery. Background technique [0002] Lithium-ion batteries have become the first choice for energy storage devices in the field of new energy vehicles due to their high energy density, long service life, and good charge and discharge performance. Affected by factors such as cruising range and state subsidies, the trend of power lithium-ion batteries to develop towards high energy density is becoming increasingly obvious. Although the application of new main materials has greatly improved the energy density of batteries, it has also brought great challenges to the safety performance ...

Claims

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Application Information

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IPC IPC(8): H01M50/403H01M50/443H01M50/449H01M50/489H01M10/0525H01M10/42
CPCH01M10/4235H01M10/0525H01M2220/20Y02E60/10
Inventor 王明华鞠署元张琪苗力孝
Owner HAIKE GRP RES INST OF INNOVATION & TECH
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