Unlock instant, AI-driven research and patent intelligence for your innovation.

A kind of three-layer co-extruded lithium battery diaphragm and preparation method thereof

A lithium battery separator, three-layer co-extrusion technology, applied in battery pack parts, circuits, flat products, etc., can solve the problem of insufficient polyethylene/polypropylene bonding, unable to meet large-scale industrial production, multi-layer co-extrusion Technical complexity and other problems, to achieve good micropore pore size consistency, avoid poor pore size uniformity, and good penetration

Active Publication Date: 2021-07-02
JIESHOU CITY TIANHONG PACKAGING MATERIAL
View PDF7 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the thickness of the multi-layer film prepared by this ex-situ composite technology of forming a microporous membrane and then recombining is relatively large; at the same time, in order not to damage the microporous structure of the lithium battery separator, the thermal composite temperature is low, polyethylene / polyethylene Insufficient bonding of propylene leads to delamination behavior of lithium battery separators under elevated temperature working conditions; for non-layered composite technology, Tang haolin et al. (J Power Sources 2013, 241, 203) adopted PVDF- HFP (vinylidene fluoride-hexafluoropropylene copolymer) is composited with ePTFE (expanded polytetrafluoroethylene) porous network, and the closed cell temperature of the prepared PVDF-HFP / ePTFE composite diaphragm is ~150 °C, because ePTFE forms a continuous network Like structure, its melting temperature (membrane rupture temperature) reaches ~350°C
However, the cost of this composite technology based on the porous network is too high to meet the needs of large-scale industrial production
[0004] The method of multi-layer co-extrusion to manufacture ultra-thin films has the advantages of high efficiency and low cost. However, for lithium battery separators that require extremely high pore structure indicators, due to the melt fluidity, crystallization and crystallization of each component at a similar temperature Transformation into differences in pore properties, multi-layer co-extrusion presents a certain technical complexity

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • A kind of three-layer co-extruded lithium battery diaphragm and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] A method for preparing a three-layer co-extruded lithium battery diaphragm, comprising melting and plasticizing polypropylene and polyethylene respectively, and casting them on a cold drum through a co-extrusion die to form cast sheets; then performing heat treatment and annealing on the cast sheets, and then The cast sheet is stretched longitudinally and transversely; finally, the lithium battery separator is obtained through heat setting treatment;

[0044] Wherein, the conditions of the heat treatment and annealing treatment include: using four heat rollers arranged at intervals to raise the temperature of the cast sheet, and the temperatures of the heat rollers are 115°C, 117°C, 118°C, and 120°C in sequence;

[0045] Then use five cooling rollers arranged at intervals to carry out gradient cooling on the cast sheet, and the temperatures of the cooling rollers are 115°C, 110°C, 105°C, 100°C, and 95°C in sequence;

[0046] The rolling speed of the chilled rolls increa...

Embodiment 2

[0051] A method for preparing a three-layer co-extruded lithium battery diaphragm, comprising melting and plasticizing polypropylene and polyethylene respectively, and casting them on a cold drum through a co-extrusion die to form cast sheets; then performing heat treatment and annealing on the cast sheets, and then The cast sheet is stretched longitudinally and transversely; finally, the lithium battery separator is obtained through heat setting treatment;

[0052] Wherein, the conditions of the heat treatment and annealing treatment include: using four heat rollers arranged at intervals to raise the temperature of the cast sheet, and the temperatures of the heat rollers are 115°C, 117°C, 118°C, and 120°C in sequence;

[0053] Then use 5 cold rollers arranged at intervals to carry out gradient cooling on the cast sheet, and the temperatures of the cold rollers are 115°C, 110°C, 105°C, 100°C, and 95°C in sequence; The distance between adjacent points of application is 80mm;

...

Embodiment 3

[0058] As in the preparation method of the three-layer co-extruded lithium battery separator provided in Example 1, the difference is that the temperatures of the four heat rollers arranged at intervals are 118°C, 120°C, 122°C, and 124°C;

[0059] With the rest unchanged, the lithium battery separator was prepared according to the method in Example 1.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
diameteraaaaaaaaaa
melt flow indexaaaaaaaaaa
densityaaaaaaaaaa
Login to View More

Abstract

The invention belongs to the technical field of lithium battery diaphragms, and in particular relates to a three-layer co-extruded lithium battery diaphragm and a preparation method thereof. The cast sheet is formed on the drum; then the cast sheet is subjected to heat treatment and annealing treatment, and then the cast sheet is stretched longitudinally and transversely; finally, the lithium battery diaphragm is obtained through heat setting treatment; the conditions for heat treatment and annealing treatment include: using multiple A hot roller arranged at intervals heats up the cast slab, and then a plurality of cold rollers arranged at intervals are used to cool the cast slab in a gradient manner; the present invention improves the crystalline structure of the cast slab by performing heat treatment and annealing, and then The polypropylene / polyethylene / polypropylene three-layer composite separator is produced through the biaxial stretching process. Its performance combines the advantages of dry and wet membranes. It has the advantages of good penetration of the dry membrane and good consistency of pore size. , and has the advantage of high wet film strength.

Description

technical field [0001] The invention belongs to the technical field of lithium battery diaphragms, and in particular relates to a three-layer co-extruded lithium battery diaphragm and a preparation method thereof. Background technique [0002] The lithium battery diaphragm is one of the key inner components of the lithium battery. Its main function is to separate the positive and negative electrodes of the lithium battery to prevent the two poles from contacting and short-circuiting; although the material of the lithium battery diaphragm is non-conductive, it has The function of allowing electrolyte ions to pass through; the performance of the separator determines the interface structure and internal resistance of the lithium battery, which directly affects the capacity, cycle and safety performance of the lithium battery. Under overcharge / overdischarge or other extreme conditions, the internal temperature of the lithium battery will rise rapidly. When the internal temperatu...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Patents(China)
IPC IPC(8): H01M50/406H01M50/403H01M50/417B29D7/01H01M50/411
CPCY02E60/10
Inventor 胡伟吴磊张德顺李汪洋何祥燕徐凤锦孙小华郭浩贺云杨建军
Owner JIESHOU CITY TIANHONG PACKAGING MATERIAL