Lithium ion battery composite membrane and preparation method thereof

A lithium-ion battery and composite diaphragm technology, which is applied in secondary batteries, battery pack components, circuits, etc., can solve the problems of complex process and difficult control of process conditions, and achieve simple process, excellent thermal stability, and improved thermal stability. sexual effect

Active Publication Date: 2016-09-21

东莞市魔方新能源科技有限公司

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AI-Extracted Technical Summary

Problems solved by technology

Such as the Chinese patents whose publication numbers are CN102569701A and CN102610773A, the composite diaphragm is obtained by first coating the insulating layer of inorganic particles on the diaphragm and then coating the polymer coating; but the preparation process of the diaphragm requires multiple coatings, and the process...

Abstract

The invention belongs to the technical field of lithium ion batteries, and especially relates to a lithium ion battery composite membrane and a preparation method thereof. The composite membrane comprises a membrane substrate and a composite coating which is coated on at least one surface of the membrane substrate; the composite coating comprises an inorganic particle, a polymer and a binder; the polymer forms adhesive polymers through the binder; and the adhesive polymers are distributed in the inorganic particle and protrude out of the surface of the inorganic particle. Compared with the prior art, the inorganic particle in the composite coating has excellent heat stability, and suppresses heat shrinkage of a traditional membrane substrate under high temperature conditions, so that the heat stability of the membrane substrate can be greatly improved; and meanwhile, the protruded adhesive polymers in the composite coating can be bonded together with a pole piece in a lithium ion battery to suppress deformation of the battery, so as to guarantee the safety and smoothness of the battery. Furthermore, the preparation method of the lithium ion battery composite membrane provided by the invention is simple in process, easy in operation and the obtained membrane is high in consistency.

Application Domain

Secondary cellsCell component details

Technology Topic

Lithium electrodeInorganic particle +7

Image

Examples

Experimental program(7)
Comparison scheme(3)
Effect test(1)

Example Embodiment

[0030] Example 1

[0031] Preparation of positive electrode sheet:

[0032] Lithium cobaltate (positive electrode active material), conductive agent superconducting carbon (Super-P), and binder polyvinylidene fluoride (PVDF) are mixed uniformly at a mass ratio of 96:2.0:2.0 to make a positive electrode slurry. Coated on the current collector aluminum foil, and then dried at 110 ℃, cold pressing, slitting, trimming, and tab welding are performed to make the positive electrode sheet of the lithium ion battery.

[0033] Preparation of negative electrode sheet:

[0034] Graphite and conductive agent superconducting carbon (Super-P), thickener sodium carboxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) are made into negative electrode slurry at a mass ratio of 96:1.5:1.0:1.5 Coating the slurry on the copper foil of the current collector, and then drying at 85°C, cold pressing, slitting, trimming, and tab welding are carried out to make a lithium ion battery negative sheet.

[0035] Preparation of composite diaphragm:

[0036] 1) Take a polyethylene microporous film with a thickness of 9 μm as the diaphragm substrate;

[0037] 2) Add polyvinylidene fluoride-hexafluoropropylene and sodium carboxymethyl cellulose to deionized water and stir for 2h at 50°C. The mass of polyvinylidene fluoride-hexafluoropropylene and sodium carboxymethyl cellulose The ratio is 95:5, agglomerate into a suspension dispersion of large particles; then add Al 2 O 3 The particles were stirred for 1 hour, and then added to the polyacrylate emulsion (the content of polyacrylate in the aqueous solution was 25wt%) and stirred for 1 hour, in which Al 2 O 3 The mass ratio with polyacrylate is 90:10, Al 2 O 3 The mass ratio to polyvinylidene fluoride-hexafluoropropylene is 50:50 to obtain a mixed slurry of inorganic particles and binding polymer, and the solid content of the mixed slurry is 42wt%;

[0038] 3) The mixed slurry obtained in step 2) is coated on both sides of the diaphragm substrate by dip coating, and after drying, a composite diaphragm with a composite coating thickness of 4 μm on each side is obtained.

[0039] Electrolyte preparation: Lithium hexafluorophosphate (LiPF 6 ) Is dissolved in a mixed solvent composed of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) with a mass ratio of 1:2:1 to obtain an electrolyte.

[0040] Lithium-ion battery preparation: the above positive electrode sheet, separator and negative electrode sheet are wound into a battery core. The composite separator is located between the adjacent positive electrode sheet and the negative electrode sheet. The positive electrode is led out by spot welding with aluminum lugs, and the negative electrode is made of nickel lugs. Lead out by welding; then put the battery core in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte, and go through the processes of packaging, forming, and capacity to make a lithium-ion battery.

Example Embodiment

[0041] Example 2

[0042] The difference from Example 1 is the preparation of the composite diaphragm:

[0043] Preparation of composite diaphragm:

[0044] 1) Take a polyethylene microporous film with a thickness of 9 μm as the diaphragm substrate;

[0045] 2) Add polyoxyethylene and styrene-butadiene to deionized water and stir for 2h at 50°C, where the mass ratio of polyoxyethylene and styrene-butadiene is 92:8, agglomerate into large particles Suspension dispersion; then add ZrO 2 The particles were stirred for 1 hour, and then added to the polyacrylate emulsion (the content of polyacrylate in the aqueous solution was 25wt%) and the stirring was continued for 1 hour, where ZrO 2 The mass ratio to polyacrylate is 85:15, ZrO 2 The mass ratio to polyoxyethylene is 60:40 to obtain a mixed slurry of inorganic particles and binding polymer, and the solid content of the mixed slurry is 40 wt%;

[0046] 3) The mixed slurry obtained in step 2) is coated on both sides of the diaphragm substrate by gravure coating, and after drying, a composite diaphragm with a composite coating thickness of 4 μm on each side is obtained.

[0047] The rest is the same as in Embodiment 1, and will not be repeated here.

Example Embodiment

[0048] Example 3

[0049] The difference from Example 1 is the preparation of the composite diaphragm:

[0050] Preparation of composite diaphragm:

[0051] 1) Take a polyethylene microporous film with a thickness of 9 μm as the diaphragm substrate;

[0052] 2) Add polymethyl methacrylate and styrene-butadiene to deionized water and stir for 2h at 40°C. The mass ratio of polymethyl methacrylate and styrene-butadiene is 94: 6. Agglomerate into a large particle suspension dispersion; then add boehmite particles and stir for 1 hour, then add sodium carboxymethyl cellulose and continue stirring for 1 hour, where the mass ratio of boehmite to sodium carboxymethyl cellulose is 90:10, the mass ratio of boehmite to polymethyl methacrylate is 70:30, and a mixed slurry of inorganic particles and binding polymer is obtained. The solid content of the mixed slurry is 45% by weight;

[0053] 3) The mixed slurry obtained in step 2) is coated on one side of the diaphragm substrate by screen printing, and a composite diaphragm with a composite coating thickness of 4 μm is obtained after drying.

[0054] The rest is the same as in Embodiment 1, and will not be repeated here.

PUM

Property	Measurement	Unit
The average particle size	0.05 ~ 6.0	µm
Particle size distribution range	0.01 ~ 10.0	µm
The average particle size	0.005 ~ 10.0	µm

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Lithium ion battery composite membrane and preparation method thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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