Diaphragm and preparation method thereof, lithium battery

A diaphragm and base film technology, which is applied in the field of diaphragm and its preparation, and lithium batteries, can solve problems such as plugging, blind holes, liquid retention, etc., achieve uniform migration distribution, good low-temperature capacity retention, and reduce internal resistance.

Active Publication Date: 2022-01-14
桑德新能源技术开发有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The main purpose of the present invention is to provide a diaphragm, its preparation method, and a lithium battery to solve the problems of plugged and blind holes and poor liquid retention in the prior art using a conductive polymer modified diaphragm with voltage-sensitive characteristics question

Method used

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  • Diaphragm and preparation method thereof, lithium battery

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Effect test

Embodiment approach

[0041] According to one embodiment of the separator of the present invention, the base film includes a polyolefin resin.

[0042] Generally speaking, the electrolyte solution of lithium battery adopts the organic solvent system, and the polyolefin resin selected in the present invention has the effect of resisting the organic solvent; in addition, the polyolefin resin also has excellent mechanical properties. In order to improve the mechanical properties of the separator, ultra-high molecular weight polyethylene is further preferred.

[0043] According to an embodiment of the diaphragm of the present invention, the thickness of the base film layer is 5-15 μm, the porosity of the base film layer is 30-60%, and the diameter of the pores in the base film layer is 40-80 nm.

[0044] In the diaphragm of the present invention, the thickness of the base film layer is preferably 5-15 μm, which not only ensures the mechanical strength of the diaphragm, but also does not affect other pr...

Embodiment 1

[0077] The preparation method of the diaphragm provided in this embodiment comprises the following steps:

[0078] Step S1: providing a base film layer containing a first electroactive polymer; specifically:

[0079] Uniformly mix ultra-high molecular weight polyethylene, polyphenylene and paraffin oil at a mass ratio of 3:3:1, heat and extrude at 180°C, cool and shape at 30°C, and simultaneously stretch longitudinally and horizontally to form a base film layer; The obtained basement film layer is subjected to the following post-treatment: the basement film layer is immersed in ethanol, and the paraffin oil in the basement film layer is extracted and washed away; and then heat-treated at 120° C. for 4 minutes. It has a thickness of 10 μm, a porosity of 45%, and a pore diameter of 60 nm.

[0080] Step S2: providing nanofiber slurry containing nanofibers and a second electroactive polymer, wherein the second electroactive polymer coats the nanofibers; specifically:

[0081] Ar...

Embodiment 2

[0085] The preparation method of the diaphragm provided in this embodiment comprises the following steps:

[0086] Step S1: providing a base film layer containing a first electroactive polymer; specifically:

[0087] Uniformly mix ultra-high molecular weight polyethylene, polyphenylene and paraffin oil at a mass ratio of 6:3:2, heat and extrude at 170°C, cool to form at 25°C, and simultaneously stretch longitudinally and horizontally to form a base film preparation layer; Immerse the obtained basement membrane preparation layer in ethanol, extract and wash off the paraffin oil in the basement membrane preparation layer; then heat-treat at 100°C for 4 minutes to obtain a basement membrane layer with a thickness of 5 μm, a porosity of 30%, and a pore size of 80 nm .

[0088] Step S2: providing nanofiber slurry containing nanofibers and a second electroactive polymer, wherein the second electroactive polymer coats the nanofibers; specifically:

[0089] Soak cellulose nanofibers...

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Abstract

The invention provides a diaphragm, a preparation method thereof, and a lithium battery. The diaphragm includes a base film layer and a nanofiber layer coated on the surface of the base film layer; wherein the base film layer contains a base film and the first electroactive polymer dispersed in the base film; the nanofiber layer contains nanofibers and coating A second electroactive polymer based on nanofibers; wherein the first electroactive polymer includes at least one of the following: polyphenylene, polynaphthine, and derivatives thereof; and / or the second electroactive polymer Including at least one of the following: polyaniline, polypyrrole, polyacetylene, and derivatives thereof. On the one hand, because of the use of nanofibers, the pore size distribution of the diaphragm is uniform due to the shape and structure of the nanofibers; on the other hand, the ionic conductivity of the diaphragm is improved because the nanofibers have excellent liquid absorption and liquid retention properties; At the same time, due to the first electroactive polymer and the second electroactive polymer, the diaphragm has the function of preventing overcharging.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a separator, a preparation method thereof, and a lithium battery. Background technique [0002] Ternary lithium-ion batteries are rising strongly because of their advantages such as high energy density, high working voltage, long service life, no memory effect, and long cruising range, and have been used in hybrid vehicles and pure electric vehicles. However, ternary lithium-ion batteries frequently explode and catch fire, and safety issues restrict their rapid development. [0003] Studies have shown that overcharging is an important factor leading to the unsafety of lithium batteries. When the battery is in an overcharged state, the cathode delithiation potential rises rapidly with the increase of the overcharge degree. When it exceeds a certain limit, it will cause irreversible oxidation and decomposition of the electrolyte inside the battery, generate flammable...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M50/449H01M50/44H01M50/403H01M10/0525B82Y30/00H01M50/454
CPCH01M10/0525B82Y30/00H01M50/44H01M50/403Y02E60/10
Inventor 郭丽媛
Owner 桑德新能源技术开发有限公司
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