Lithium ion battery composite gel diaphragm as well as preparation method and application thereof

A lithium ion battery and composite gel technology, which is applied in the field of lithium ion battery composite gel separator and its preparation, can solve the problems of high porosity of the separator, and achieves the improvement of safety performance, excellent liquid absorption performance and high tensile strength. Effect

Inactive Publication Date: 2021-06-25
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, the existing diaphragm modification methods are difficult to ensure that the diaphragm has high mechanical strength and high-temperature self-closing performance while having high porosity and liquid absorption rate.
Therefore, we urgently need to develop a high-strength lithium-ion battery gel separator to solve the existing safety hazards

Method used

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  • Lithium ion battery composite gel diaphragm as well as preparation method and application thereof
  • Lithium ion battery composite gel diaphragm as well as preparation method and application thereof
  • Lithium ion battery composite gel diaphragm as well as preparation method and application thereof

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preparation example Construction

[0036] The present invention also provides a preparation method of the lithium-ion battery composite gel diaphragm described in the above technical solution, comprising the following steps:

[0037] (1) Provide aramid nanofiber casting solution;

[0038] (2) gelling the aramid nanofiber casting solution to obtain the aramid nanofiber hydrogel film;

[0039] (3) drying the aramid nanofiber hydrogel film to obtain an aramid nanofiber diaphragm;

[0040] (4) The polyvinylidene fluoride-hexafluoropropylene solution is electrospun onto both sides of the aramid nanofiber separator, and then dried to obtain a lithium-ion battery composite gel separator.

[0041] In the present invention, unless otherwise specified, each component is a commercially available product well known to those skilled in the art.

Embodiment 1

[0052] Preparation of lithium-ion battery composite gel separator:

[0053] (1) Aramid nanofiber casting solution is provided, and the specific steps include: dispersing aramid fiber and potassium hydroxide with a mass ratio of 1:1 in 100 mL of dimethyl sulfoxide, at a temperature of 30 ° C and a rotation speed of Under the condition of 600r / min, stir for 7 days. During the stirring process, the micron-sized aramid fibers are deprotonated and dissociated into nano-sized aramid fibers to form aramid nanofiber casting solution with a mass fraction of 0.5 wt.%.

[0054] (2) gelling the aramid nanofiber casting solution to obtain the aramid nanofiber hydrogel film, the specific steps include: scraping and coating the aramid nanofiber casting solution with a mass fraction of 0.5wt.% on a glass plate by a scraper superior. Then, soak the glass plate coated with the aramid nanofiber casting solution in deionized water for 12 hours to obtain the aramid nanofiber hydrogel film.

[0...

Embodiment 2

[0058] Preparation of lithium-ion battery composite gel separator:

[0059] (1) Provide aramid nanofiber casting solution, the specific steps include: dispersing aramid fiber and potassium hydroxide with a mass ratio of 1:2 in 150mL of dimethyl sulfoxide, at a temperature of 50°C, stirring speed Under the condition of 700r / min, stir for 10 days. During the stirring process, the micron-scale aramid fibers are deprotonated and dissociated into nano-scale aramid fibers, forming a casting liquid with a mass fraction of 1 wt% aramid nanofibers.

[0060] (2) gelling the aramid nanofiber casting solution to obtain the aramid nanofiber hydrogel film, the specific steps include: scraping and coating the aramid nanofiber casting solution with a mass fraction of 1wt% on a glass plate by a scraper superior. Then, soak the glass plate coated with the aramid nanofiber casting solution in deionized water for 12 hours to obtain the aramid nanofiber hydrogel film.

[0061] (3) drying the ar...

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Abstract

The invention belongs to the field of battery diaphragms, and particularly relates to a lithium ion battery composite gel diaphragm as well as a preparation method and application thereof. The lithium ion battery composite gel diaphragm provided by the invention is of a three-layer composite structure, the middle layer is an aramid nanofiber diaphragm, and the two sides are polyvinylidene fluoride-hexafluoropropylene gel diaphragms. The composite gel diaphragm provided by the invention has the characteristics of high liquid absorption rate, high modulus and high strength, also has excellent performance of high-temperature hole closing, and is an ideal polymer gel diaphragm. The composite gel diaphragm provided by the invention has the liquid absorption rate of 320%, the tensile strength of 177.6 MPa and the Young modulus of 4.58 GPa. Moreover, a half battery assembled by the gel diaphragm provided by the invention shows excellent electrochemical performance, the reversible capacity can still be stabilized at 145.2 mAh.g <-1 > after 300 cycles, and the capacity retention rate is 92.01%.

Description

technical field [0001] The invention belongs to the field of battery separators, and in particular relates to a lithium-ion battery composite gel separator and a preparation method thereof. Background technique [0002] At present, commercial lithium-ion battery separator products mainly include polyethylene (PE), polypropylene (PP), and polyethylene-polypropylene (PE-PP) composite films. However, existing battery separators have low mechanical strength, which poses major safety concerns when the battery is subjected to high charge-discharge rates or when the battery temperature is too high. The focus of improving the safety of liquid lithium-ion batteries is to solve the problem of thermal runaway of the battery. Thermal runaway is caused by external mechanical impact on the battery, mechanical tearing of the diaphragm, overcharging, dendrite lithium precipitation, and puncture of the diaphragm. Therefore, how to improve the strength of the separator and realize practical...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/414H01M50/417H01M50/409H01M50/44H01M10/0525
CPCY02E60/10
Inventor 张校刚贺文杰王思堪蒋江民
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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