Diaphragm for secondary battery, preparation method of diaphragm and secondary battery

A secondary battery and diaphragm technology, applied in the field of secondary battery diaphragm and its preparation, can solve the problems of inability to carry out the combustion process of the electrolyte solution, reduce the ionic conductivity of the electrolyte solution, decrease the electrochemical performance, etc. Good cycle performance, preventing thermal runaway and explosion effects

Pending Publication Date: 2022-05-13
惠州锂威电子科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, researchers can effectively suppress the spread of fire in lithium-ion batteries by adding flame retardants to the electrolyte, because the flame retardants capture combustion radicals in the gas phase when heated And then block the chain reaction of free radicals, so tha

Method used

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  • Diaphragm for secondary battery, preparation method of diaphragm and secondary battery
  • Diaphragm for secondary battery, preparation method of diaphragm and secondary battery
  • Diaphragm for secondary battery, preparation method of diaphragm and secondary battery

Examples

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Example Embodiment

[0038] The second object of the present invention is to provide a method for preparing a separator for the secondary battery as described above, comprising the following steps:

[0039] S1, the methyl methacrylate, crosslinking agent, surfactant, solvent, initiator and flame retardant mixed to form a uniform solution, and remove the reactive oxygen species therein, and then heated to 40 ~ 50 ° C and at a speed of 200 ~ 300 rpm / min polymerization reaction for 5 ~ 6h; after the reaction, take out the synthetic flame retardant capsule, wash and dry for more than 24h;

[0040] S2, the polyvinylidene fluoride - hexafluoropropylene binder dissolved in a volatile solvent, and then step S1 obtained flame retardant capsules added to it and stirred, and then the base film 1 immersed in it, take out the base film 1, after drying to obtain a secondary battery separator containing flame retardant layer 2.

[0041] In step S1, methyl methacrylate (MMA) is first mixed and dispersed with a cros...

Example Embodiment

[0052] Example 1

[0053] A kind of secondary battery with a separator, such as Figure 1 Shown, comprising a PE base film 1 and a flame retardant layer coated on at least one surface of the PE base film 1 2; the flame retardant layer 2 consists of polyvinylidene fluoride - hexafluoropropylene (PVDF-HFP) binder and flame retardant capsule composition, the flame retardant capsule is a trimethyl phosphate as the core, polymethyl methacrylate (PMMA) as the shell of the core shell structure.

[0054] The preparation method of the diaphragm may be, as in Figures 2 to 4 shown, including the following steps:

[0055] S1, preparation of flame retardant capsules: In a three-mouth flask, 30ml of methyl methacrylate (MMA, monomer) and 0.3ml of glycol dimethacrylate (EGDMA, crosslinking agent) were added to 500ml of deionized water and 2.5g of terraton X-100 (surfactant) and N 2 The reactive oxygen species in the three flasks were removed, and stirred for 30 min at 800 rpm / min to form a unifo...

Example Embodiment

[0057] Example 2

[0058] Different from Example 1 is the preparation method of flame retardant capsules.

[0059] S1, preparation of flame retardant capsules: In a three-mouth flask, 30ml of methyl methacrylate (MMA, monomer) and 0.3ml of glycol dimethacrylate (EGDMA, crosslinking agent) were added to 500ml of deionized water and 2.5g of terraton X-100 (surfactant) and N 2 Remove the reactive oxygen species in the three flasks, and stir for 30 min at 800 rpm / min to form a uniform mixture; then take 30mL trimethyl phosphate, 0.3g 2,2-azo bis (2,4-dimethylpentonitrile) (ADVN, initiator) was added therein, stirred at 1800 ~ 2000 rpm / min for 20 min to form a uniform solution; then heated to 45 ° C and polymerization reaction at a speed of 1800 ~ 2000 rpm / min for 5h After the reaction is completed, an excess of NaCl is added to precipitate the synthetic flame retardant capsules, filtered, washed 3 times with water and ethanol and then dried and sticky at room temperature for 1 d...

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Abstract

The invention provides a diaphragm for a secondary battery, a preparation method of the diaphragm and the secondary battery. The diaphragm comprises a base film and a flame-retardant layer coated on at least one surface of the base film, the flame-retardant layer is composed of a polyvinylidene fluoride-hexafluoropropylene binder and a flame-retardant capsule, and the flame-retardant capsule is of a core-shell structure with a flame retardant as an inner core and polymethyl methacrylate as an outer shell. Compared with the prior art, according to the diaphragm provided by the invention, when the battery is subjected to thermal runaway, the PMMA shell is broken and can release the flame retardant, the flame retardant can capture combustion free radicals and can effectively prevent thermal runaway and explosion of the battery, and the PMMA shell is adopted, so that better bonding force can be provided for the diaphragm and a pole piece; the problem that the cycle life of the battery is difficult to guarantee while the thermal runaway of the secondary battery is blocked at present is solved.

Description

technical field [0001] The invention relates to the field of secondary batteries, in particular to a diaphragm for a secondary battery, a preparation method thereof, and a secondary battery. Background technique [0002] Lithium-ion batteries are considered to be the most promising power source for electric vehicles (EVs) due to their high specific energy density, lack of memory effect, and excellent cycling performance. However, due to the sharp increase in the energy density of lithium-ion batteries or the possibility of battery fire and explosion after a car collision, ensuring sufficient safety of lithium-ion batteries has become one of the most important issues at present. Studies have shown that the safety of lithium-ion batteries is closely related to the flammable components in the electrolyte and pole pieces. Once the inside / outside of the lithium-ion battery is on fire due to a short circuit, the flammable components (especially the cathode and flammable oxides of ...

Claims

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Application Information

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IPC IPC(8): H01M50/409H01M50/403H01M50/489H01M10/0525
CPCH01M50/409H01M50/403H01M50/489H01M10/0525
Inventor 赖旭伦
Owner 惠州锂威电子科技有限公司
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