Isolation diaphragm for secondary polymer lithium cell and its making method

A manufacturing method and technology of separator, applied in battery pack parts, circuits, electrical components, etc., can solve the problems of thickness not less than 50 microns, low mechanical strength of separator, poor wettability of electrolyte, etc. High energy density, good adhesion and good wettability

Inactive Publication Date: 2005-03-09
DONGGUAN NEWPOWER ELECTRIC SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has been commercialized, but due to the low mechanical strength of the isolation film made by this method, the practical thickness should not be less than 50 microns
There are also people who directly use polyethylene (PE), polypropylene (PP) or a composite film of polyethylene and polypropylene as the separator, but the interface effect between the separator and the electrode manufactured in this way is large, and the electrolyte is not wetted. Poor humidity will affect battery performance

Method used

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  • Isolation diaphragm for secondary polymer lithium cell and its making method
  • Isolation diaphragm for secondary polymer lithium cell and its making method
  • Isolation diaphragm for secondary polymer lithium cell and its making method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0029] One, the preparation method of phase separation porous isolation membrane:

[0030] (1) Prepare separator slurry: dissolve vinylidene fluoride and hexafluoropropylene copolymer (PVDF-HFP) or polyvinylidene fluoride (PVDF) (5-30%, mass percentage, the same below) in an organic solvent, Join Al 2 o 3 or SiO 2 Inorganic matter powder (1-20%), mix evenly, add phase separation agent after stirring evenly. Organic solvents can be composed of propenyl carbonate (PC), ethyl acetate (EtAc), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), acetone (ACE), butyl One or more of organic polar solvents such as ketone, N, N-dimethylpyrrolidone (NMP), and cyclohexanone. The phase separation agent can be composed of one or more of water, methanol, ethanol, butanol, ethylene glycol, glycerol, and isobutanol.

[0031] (2) Evenly coat the isolation film slurry on the film made of PET, PE, PP, PVC, centrifugal paper and other materials according to the re...

Embodiment 1

[0046] Isolation film:

[0047] (1) Preparation of separator slurry: dissolve vinylidene fluoride and hexafluoropropylene copolymer (PVDF-HFP) (18%, mass percentage, the same below) in acetone, polystyrene (PS) (6%) In dimethyl carbonate (DMC). Mix the two solutions well, then add SiO 2 (5%), after stirring evenly, slowly add ethanol. After stirring, let stand for more than 30 minutes.

[0048] (2) Coat the isolation film slurry on the PET according to the required thickness, and then dry at a temperature of 75°C.

[0049] The main parameters and performance of the secondary polymer lithium battery made of this separator are as follows:

[0050] Capacity: 807mAh

[0051] Charging cut-off voltage: 4.2V

[0052] Discharge cut-off voltage: 3.0V

[0053] Its charging curve at 0.5C (C is the charge and discharge rate potential, indicating the number of charges and discharges per hour) is shown in image 3 , its discharge curves and cycle life curves at different rates are s...

Embodiment 2

[0055] Isolation film:

[0056] (1) Preparation of separator slurry: polyvinylidene fluoride (12%) was dissolved in N,N-dimethylpyrrolidone (NMP), and polystyrene (15%) was dissolved in dimethyl carbonate. Then mix the two solutions evenly and add SiO 2 (5%), after stirring evenly, slowly add ethanol, after stirring, let it stand for more than 30 minutes.

[0057] (2) Coat the separator slurry on the PET according to the required thickness, and then dry it at 95°C.

[0058] The main parameters and performance of the secondary polymer lithium battery made of this separator are as follows:

[0059] Capacity: 776mAh

[0060] Charging cut-off voltage: 4.2V

[0061] Discharge cut-off voltage: 3.0V

[0062] Its charging curve at 0.5C see Image 6 , the discharge curves at different rates are shown in Figure 7 .

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Abstract

This invention discloses a method for using the multipolymer of PVDF or VDF with hexafluoropropylene as the host and utilizing phase separation, polymer alloy and cross-link technology to prepare a new type of porous isolation membrane and its manufacturing method. The thickness of the isolation membrane is 15-50 mum with the advantage of high strength, uniform slots, high conductivity, which is well immersed into the electrolyte and not necessary to be extracted.

Description

Technical field: [0001] The invention relates to the technical field of secondary polymer lithium batteries, and more specifically relates to a separator used in secondary polymer lithium batteries and a manufacturing method thereof. Background technique: [0002] With its high energy, high reliability, good processability and no environmental pollution, the secondary polymer lithium battery has been strongly attracting battery researchers and manufacturers since its inception. Among the four types of polymer electrolytes currently available in secondary polymer lithium batteries (doubling as separators), the polymer electrolytes that do not contain any liquid systems and ionic rubber systems are still in the development stage; and the preparation of gel polymer electrolyte systems The process is relatively complex and has strict requirements on environmental humidity. For example, Bell Core, USA published a method for preparing a plasticized polymer electrolyte in 1994 (US ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J5/22H01M2/14
CPCY02E60/10
Inventor 许瑞龙猛赵丰刚曾毓群吴凯方祺王乾杜旭东
Owner DONGGUAN NEWPOWER ELECTRIC SCI & TECH
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