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Lithium ion battery separator with low thermal shrinkage rate and preparation method therefor

A lithium-ion battery, shrinkage rate technology, applied in secondary batteries, battery pack parts, secondary battery repair/maintenance, etc., can solve the problems of poor wettability of electrolyte, etc., to reduce thermal shrinkage rate, good wettability, Good safety and long-lasting effect

Inactive Publication Date: 2015-12-23
HUIQIANG WUHAN NEW ENERGY MATERIAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The wettability of the lithium-ion battery separator is another important indicator that affects the performance of the lithium-ion battery. The commonly used lithium-ion battery separator has poor electrolyte wettability due to the hydrophobicity of the membrane.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] 1) Mix wood pulp cellulose with a polymerization degree of 600, sodium hydroxide, urea, and water in a mass ratio of 1:0.3:0.2:5, and stir in an ice bath for 4 hours to obtain a cellulose carbamate solution.

[0026] 2) Cellulose coating: The cellulose carbamate solution prepared in step 1) was scraped and coated on both sides of the PE separator of the lithium-ion battery, and the solvent was dried at 90°C.

[0027] 3) Cellulose regeneration: Soak the PE diaphragm coated with cellulose carbamate obtained in step 2) in 0.5mol / L sulfuric acid for 20min to regenerate the cellulose carbamate into cellulose, and then deionized water The cellulose-coated PE separator was obtained after washing 3 times and drying at 90 °C.

[0028] The cellulose-coated PE separator was tested with a thermomechanical analyzer, and the temperature when it reached 5% heat shrinkage was 132°C. When a certain size of cellulose-coated PE separator was dripped with a certain amount of electrolyte s...

Embodiment 2

[0031] 1) Mix cotton pulp cellulose with a polymerization degree of 300, sodium hydroxide, urea, and water at a mass ratio of 1:0.05:0.1:20, and stir in an ice bath for 1 hour to obtain a cellulose carbamate solution.

[0032] 2) Cellulose coating: The cellulose carbamate solution prepared in step 1) was scraped and coated on both sides of the three-layer PP / PE / PP separator of the lithium ion battery, and the solvent was dried at 85°C.

[0033] 3) Cellulose regeneration: Soak the three-layer PP / PE / PP diaphragm coated with cellulose carbamate obtained in step 2) in 0.3mol / L sulfuric acid for 15min to regenerate the cellulose carbamate into fibers After washing with deionized water three times, a cellulose-coated three-layer PP / PE / PP separator was obtained after drying at 90 °C.

[0034] The cellulose-coated three-layer PP / PE / PP separator was tested with a thermomechanical analyzer, and the temperature when it reached 5% heat shrinkage was 137°C. When a certain size of cellulos...

Embodiment 3

[0037] 1) Mix wood pulp cellulose with a polymerization degree of 400, sodium hydroxide, urea, and water at a mass ratio of 1:0.2:0.14:12, and stir in an ice bath for 3 hours to obtain a cellulose carbamate solution.

[0038] 2) Cellulose coating: the cellulose carbamate solution prepared in step 1) was scraped and coated on both sides of the PE separator of the lithium-ion battery, and the solvent was dried at 85°C.

[0039] 3) Cellulose regeneration: Soak the PE diaphragm coated with cellulose carbamate obtained in step 2) in 0.8mol / L sulfuric acid for 10min to regenerate the cellulose carbamate into cellulose, and then deionized water After washing 3 times and drying at 85°C, a cellulose-coated PE separator for lithium-ion batteries was obtained.

[0040] The cellulose-coated PE separator was tested with a thermomechanical analyzer, and the temperature when it reached 5% heat shrinkage was 134°C. When a certain size of cellulose-coated PE separator was dripped with a certa...

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Abstract

The invention belongs to the production field of lithium batteries, in particular to a lithium ion battery separator with low thermal shrinkage rate and a preparation method therefor. The surface of the lithium ion battery separator with the low thermal shrinkage rate is uniformly coated with a cellulose layer; and a porous membrane base material is any one of a PE single-layer membrane, a PP single-layer membrane or a PP / PF / PP three-layer co-extruding membrane. The preparation method provided by the invention is as follows: cellulose dissolving, mixing the cellulose, strong alkali, urea and water at a proper proportion to obtain a cellulose carbamate solution; cellulose coating, coating the solution on the surface of the porous membrane base material and drying; and cellulose regenerating, immersing the porous membrane base material which is coated with the cellulose into a sulfuric acid solution at a certain concentration to regenerate, and drying. The lithium ion battery separator and the preparation method therefor have the beneficial effects that: the coating layer is in tight contact with the porous membrane base material without falling easily; the thermal shrinkage rate of the diaphragm is greatly reduced; the lithium ion battery separator is higher in electrolyte wettability; the capacity fading of the battery can be effectively reduced; and the cellulose of waste batteries can be dissolved and reused, so that the lithium ion battery separator is energy-saving and environment-friendly.

Description

technical field [0001] The invention belongs to the field of lithium battery production, and in particular relates to a lithium-ion battery diaphragm with low thermal shrinkage rate and a preparation method thereof. Background technique [0002] Lithium-ion battery is a secondary battery with high energy density. With the development of the times, its cost has gradually decreased and its application has been promoted, especially in the fields of electric vehicles and energy storage. However, the safety of lithium-ion batteries restricts its further development and application. The separator is an important component of the lithium-ion battery. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle performance and safety of the battery. The electrolyte can penetrate the separator, and the positive and negative electrodes are separated by the separator to prevent short circuit cau...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/14H01M10/0525H01M10/42H01M50/403H01M50/411H01M50/44H01M50/489
CPCH01M10/0525H01M10/4235H01M50/403H01M50/449H01M50/411H01M50/44Y02E60/10
Inventor 唐浩林王红兵王锐边红兵
Owner HUIQIANG WUHAN NEW ENERGY MATERIAL TECH
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