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Battery diaphragm, preparation method thereof and lithium ion battery

A battery diaphragm and lithium battery technology, applied in the field of battery materials, can solve the problems of poor high temperature resistance, short circuit or even combustion and explosion of the battery diaphragm, and achieve the effects of good mechanical properties, anti-polarization, and uniform structure

Inactive Publication Date: 2019-03-15
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the problems of poor high temperature resistance of battery separators in the prior art and easy short circuit or even combustion and explosion under high temperature conditions, and provide a battery separator and its preparation method and lithium battery

Method used

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  • Battery diaphragm, preparation method thereof and lithium ion battery
  • Battery diaphragm, preparation method thereof and lithium ion battery
  • Battery diaphragm, preparation method thereof and lithium ion battery

Examples

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preparation example Construction

[0033] In the preparation method of the present invention, the spinning method can be any spinning method capable of forming a core-shell structure, and preferably, a coaxial spinning method is selected. Specifically, such as figure 1 As shown, the coaxial spinning structure is adopted, and the solution of temperature-resistant polymer material is injected into the outer shaft cavity as the outer shaft solution, and the flame retardant is injected into the inner shaft cavity, and fibers with a cavity structure are formed along with the outer shaft solution. , the flame retardant is filled inside. If the flame retardant is a solid particle, the flame retardant is first dissolved or dispersed in a solvent and then filled in the inner shaft cavity.

[0034] In the preparation method of the present invention, specifically, in the present invention, when coaxial (electrostatic) spinning is adopted, the solutions of the inner axial cavity (core layer) and the outer axial cavity (she...

Embodiment 1

[0046] Using N,N-dimethylacetamide as a solvent, configure poly-m-phenylene isophthalamide (aramid 1313, PMIA) spinning solution, and poly-m-phenylene isophthalamide in spinning solution The concentration is 15wt%. The coaxial spinning structure is adopted, and the flame retardant polyphosphate is injected into the inner shaft cavity, and the two surfaces of the polyethylene (PE) base film with a thickness of 11 μm are spun by coaxial spinning, wherein, The flow rate of the spinning solution was 1.0 mL / h, the spinning temperature was 40° C., the spinning humidity was 25%, the voltage was 10 kV, and the rotational speed of the metal drum was 1500 rpm. The average diameter of the fibers forming the spinning layer is 310nm (between 300-320nm), and the average thickness of the shell formed by the heat-resistant polymer material is 75nm (between 50-100nm).

[0047] After obtaining the polym-phenylene isophthalamide-polyphosphate fiber membrane, press the membrane under a pressure ...

Embodiment 2

[0049] Using N-methylpyrrolidone as a solvent, a polyetherimide (PEI) spinning solution is prepared, and the concentration of the polyetherimide in the spinning solution is 20 wt%. The coaxial spinning structure is adopted, and the flame retardant isocyanurate is injected into the inner shaft cavity, and the spinning is carried out on one surface of the 11 μm polyethylene (PE) base film by means of coaxial spinning. The flow rate of the silk liquid is 2.0 mL / h, the spinning temperature is 30° C., the spinning humidity is 50%, the voltage is 20 kV, and the rotation speed of the metal drum is 1000 rpm. The average diameter of the fibers forming the spinning layer is 385nm (between 350-420nm), and the average thickness of the shell formed by the heat-resistant polymer material is 125nm (between 100-150nm).

[0050] After obtaining the polyetherimide-isocyanurate fiber membrane, press the membrane under a pressure of 5 MPa for 3 minutes to obtain a spinning layer with a thickness ...

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Abstract

The invention relates to the technical field of battery materials, and discloses a battery diaphragm. The battery diaphragm comprises a base membrane and a spinning layer formed on one surface or twosurfaces of the base membrane, wherein the spinning layer comprises a composite fiber with a core-shell structure; and the composite fiber comprises a fire retardant serving as a core and a high temperature-resistant high polymer material serving as a shell. The battery diaphragm has favorable stability under high temperature and has small high temperature thermal shrinking percentage. Moreover, the spinning layer is provided with a protection layer by the high temperature-resistant high polymer material and is filled with the fire retardant, so as to prevent the fire retardant from being in contact with electrolyte at ordinary time and not influence the performance of the electrolyte under normal state. When the battery is slightly overheated, the protection layer is not damaged, so thatthe performance play space of the battery is increased. When the battery is seriously overheated or suffers thermal runaway to cause the diaphragm to be squeezed out or cause the heat-resistant fibershell to be fused, the fire retardant is released to inhibit the combustion of the electrolyte.

Description

technical field [0001] The invention relates to the field of battery materials, in particular to a battery diaphragm, a preparation method thereof, and a lithium battery. Background technique [0002] Lithium battery is currently the power battery system with the most application value and development prospect. The diaphragm plays the role of isolating the positive and negative electrodes in the lithium battery to prevent short circuit, and its safety performance largely determines the safety of the entire battery. Currently commonly used separator materials are mostly polyolefin materials, such as PP and PE, which have high porosity and high strength, but have low liquid absorption, poor thermal stability and are prone to thermal runaway. [0003] CN104377329A discloses a heat-resistant and flame-retardant diaphragm and a preparation method thereof. The method mainly involves reacting and copolymerizing melamine, formaldehyde and some auxiliary agents, and then preparing a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/052H01M50/403H01M50/417H01M50/443H01M50/457H01M50/491
CPCH01M10/052H01M50/403H01M50/411H01M50/44H01M50/449Y02E60/10
Inventor 胡家玲单军
Owner BYD CO LTD
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