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Lithium ion battery diaphragm with special structure and preparation method thereof

A lithium-ion battery and a special structure technology, applied in structural parts, battery pack parts, circuits, etc., can solve the problems of difficult to obtain uniform slurry, limit the electrical performance of the diaphragm, reduce the porosity of the diaphragm, and achieve large-scale industrialization Production, film thickness can be adjusted at will, and the effect of lithium ion conductivity improvement

Inactive Publication Date: 2013-05-01
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Recent studies have found that although the effect of ceramic coating on improving the heat resistance of the diaphragm is very significant, the binder used in the preparation of the ceramic coating has brought some troubles, such as nano-ceramic particles are easy to agglomerate in the binder, even if ball milling Auxiliary dispersion is also difficult to obtain a uniform slurry, resulting in poor consistency of the coating, which in turn leads to uneven current density; the binder coats the surface of the ceramic particles, reducing the electrolyte wettability of the separator; part of the binder fills the separator Microporosity reduces the porosity of the separator, which in turn affects the conductivity of lithium ions; the agglomerated particles are easy to fall off during the battery assembly process, resulting in defects such as pinholes in the separator, which seriously affects the performance of the battery
The study found that when the mass fraction of the binder (PVDF-HFP) in the coating slurry was reduced from 70% to 10%, the lithium ion conductivity of the composite film increased from 0.25mS cm -1 up to 0.91mS cm -1 , it can be seen that the binder content seriously affects the porosity and electrolyte wettability of the separator. Although a high content of binder improves the structural stability of the membrane, it will block most of the pores of the separator and limit the electrical performance of the separator.
In order to overcome the above problems, the researchers did not use adhesives, by 2 o 3 Pure ceramic lithium battery separators with good performance can be prepared by powder pressing and calcination, but the separators are brittle, and further research is needed in terms of battery structure design and assembly.

Method used

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  • Lithium ion battery diaphragm with special structure and preparation method thereof
  • Lithium ion battery diaphragm with special structure and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0035] Slowly add 8g of polyurethane thickener to 200ml of ethanol, stir vigorously and mix evenly. Add 24g of NaA-type zeolite particles (with a particle size of about 2.5 μm) to the above solution, and continue to stir for 2 hours to obtain a uniformly mixed suspension. Then add 6.5g of polypropylene microspheres (particle size is about 0.8μm) to the above suspension, continue to stir for 4h, and obtain a uniform coating slurry after vacuum defoaming treatment. Using a dip coating machine, polyester non-woven fabric (gram weight 17 g / square meter, thickness 20 μm, porosity 65%, pore size distribution uniform, average pore size 18 μm, see figure 1 ) before and after coating the above slurry, the dipping time is 120s, the pulling speed is 1cm / s, dipping once. After coating, it was dried in a constant temperature oven at 40°C for 5 hours, and finally rolled into a tablet press at 150°C with a roller spacing of 50 μm to obtain an inorganic-coated lithium-ion battery separator. ...

Embodiment 2

[0038] Slowly add 8g of polyurethane thickener to 200ml of ethanol, stir vigorously and mix evenly. Add 24g Al to the above solution 2 o 3 Particles (particle size is about 1.0 μm), continue to stir for 2 hours to obtain a well-mixed suspension. Then add 6.5g of polypropylene microspheres (particle size is about 0.8μm) to the above suspension, continue to stir for 4h, and obtain a white uniform coating slurry after vacuum defoaming treatment. Use a dip coating machine to coat the above slurry on both sides of the polyester non-woven fabric (weight 25 g / m2, thickness 20 μm, porosity 60%, uniform pore size distribution, average pore size 10 μm), and the dipping time is 120s , the pulling speed is 1cm / s, dipping once. After coating, it was dried in a constant temperature oven at 40°C for 5 hours, and finally rolled into a tablet press at 150°C with a roller spacing of 80 μm to obtain an inorganic-coated lithium-ion battery separator.

[0039] In this example, the technical pa...

Embodiment 3

[0041] Slowly add 1.5g sodium carboxymethylcellulose into 200ml water, stir vigorously and mix well. Add 24g of NaA-type zeolite particles (with a particle size of about 2.5 μm) to the above solution, and continue to stir for 2 hours to obtain a uniformly mixed suspension. Then add 6.5g of polystyrene microspheres (particle size is about 0.6μm) to the above suspension, continue to stir vigorously for 4h, and obtain a white uniform coating slurry after vacuum defoaming treatment. Use a dip coating machine to coat the above slurry on both sides of the porous polypropylene base film (thickness 22 μm, porosity 40%, uniform pore size distribution, average pore size 1.0 μm), the dipping time is 150 s, and the pulling speed is 1 cm / s, impregnated twice. After coating, it was dried in a constant temperature oven at 40°C for 5 hours, and finally rolled into a tablet press at 120°C with a roller spacing of 30 μm to obtain an inorganic-coated lithium-ion battery separator.

[0042] In...

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Abstract

The invention relates to the field of lithium ion battery diaphragm preparation and relates to an inorganic coating high-temperature resisting type lithium ion battery diaphragm with a special structure and the preparation method thereof. The lithium ion battery diaphragm comprises a porous flexible basement membrane and coatings coated on the two sides of the basement membrane, and composites of inorganic particles and organic microsphere are contained in the coatings. The inorganic particles and the organic microspheres are mixed into the solvent according to a certain proportion, homogeneous membrane coating slurry can be obtained, the slurry is coated on the two surfaces of the flexible and organic basement membrane, and then, under a certain temperature, the composite diaphragm with favorable performance is obtained through the pressing of a hot roller. In the inorganic coating lithium ion battery diaphragm provided by the invention, bonding agent is not directly added into the membrane coating slurry, damages to the microstructure of the diaphragm caused by the bonding agent can be avoided, the high-temperature resisting performance and the electrolyte infiltrating performance of the diaphragm are greatly improved, and the composite lithium ion battery diaphragm prepared by the invention has the advantages of superior comprehensive performance, easiness in big-scale and large-dimension production and the like.

Description

technical field [0001] The invention relates to the field of lithium-ion battery diaphragm preparation, in particular to a high-temperature-resistant lithium-ion battery diaphragm with a special structure inorganic coating and a preparation method thereof. Background technique [0002] Lithium-ion batteries have become the main power source of various portable electronic products due to their advantages such as high working voltage, high energy density, no memory effect, long cycle life and low self-discharge. In recent years, with the promotion of new energy industries such as electric vehicles and energy storage batteries, power lithium batteries have received more attention. [0003] Lithium-ion batteries are composed of four parts: positive electrode, negative electrode, electrolyte and separator. As a key material of lithium-ion batteries, research on separators suitable for power-type lithium-ion batteries has attracted extensive attention from researchers. Improving ...

Claims

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Application Information

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IPC IPC(8): H01M2/16
CPCY02E60/12Y02E60/10
Inventor 肖伟赵丽娜刘建国严川伟
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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