Battery diaphragm, preparation method thereof and battery

A technology of battery separator and base film, which is applied in secondary batteries, battery pack components, and secondary battery repair/maintenance, etc., can solve the problems of smaller surface area of ​​the diaphragm, internal short circuit, thermal runaway, etc., to suppress thermal runaway. , the effect of increasing the safety of use

Active Publication Date: 2021-07-13
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to its low melting point (only 136°C for polyethylene and 165°C for polypropylene), it has severe heat shrinkage properties
This feature will lead to a smaller diaphragm area, which can easily cause a short circuit in the battery and cause thermal runaway
[0004] In addition, the thermal runaway that occurs at the separator level is not only due to the smaller area, but also the internal short circuit and thermal runaway caused by gaseous substances passing through the separator between the positive and negative electrodes.

Method used

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  • Battery diaphragm, preparation method thereof and battery
  • Battery diaphragm, preparation method thereof and battery
  • Battery diaphragm, preparation method thereof and battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0069] 1. Preparation of battery separator

[0070] Step 1: Preparation of polymer base film

[0071] 1) Take 15g of polym-phenylene isophthalamide, dissolve it in 85g of dimethylformamide solvent, then add 35wt% polyvinyl alcohol and 7wt% alumina as additives to prepare a solution, and let it stand for 24 hours to prepare Liquid film;

[0072] 2) Put the liquid film in a mixed solution of methylpyrrolidone and ethanol (volume ratio=8:1) to react for 24 hours to obtain a gel state film;

[0073] 3) At a stretch ratio of 135%, the gel state film is stretched and oriented by bidirectional simultaneous stretching;

[0074] 4) placing the oriented gel film in a mixed solution of hydrogen peroxide and water (volume ratio=3:7) for 72 hours to obtain a solid film;

[0075] 5) After rolling the solid film at 120°C, place it in a blast oven at 250°C and heat it for 10 hours to obtain a 16 μm thick polym-phenylene isophthalamide base film. The average pore diameter of the base film i...

Embodiment 2

[0109] 1. Preparation of battery separator

[0110] Step 1: Preparation of polymer base film

[0111] 1) Take 17.5g of polyamic acid, dissolve it in 100g of dimethylformamide solvent, add 50wt% polyethylene glycol (PEG600) and 3wt% graphene as additives, prepare a solution, and let it stand for 24h to form a liquid film ;

[0112] 2) Put the liquid film in a mixed solution of isopropanol, dimethylformamide and toluene (volume ratio=5:4:1) to react for 24 hours to obtain a gel film;

[0113] 3) By bidirectional asynchronous stretching, the transverse stretching ratio is 120%, and the longitudinal stretching ratio is 150%, and the gel state film is stretched and oriented;

[0114] 4) placing the oriented gel state film in a mixed solution of n-octane and toluene (volume ratio = 1:1) for 24 hours to obtain a solid film;

[0115] 5) React the solid film at 80°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C for 10h, 2h, 2h, 2h, 1h, 1h, 0.5h, After 0.5 h and 2 h, a pol...

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Abstract

The invention relates to the technical field of batteries, in particular to a battery diaphragm, a preparation method thereof and a battery. The preparation method comprises: loading the core-shell structure composition on a porous and heat-shrinkage-free polymer base membrane, wherein a core body in the core-shell structure composition is made of a metal organic framework material, and a shell layer is made of a polymer material with a melting point of 150-220 DEG C. The method for preparing the porous and heat-shrinkage-free polymer-based membrane comprises the following steps: dissolving an organic polymer which contains polar groups and is resistant to 250-500 DEG C in a first organic solvent to prepare a liquid membrane; swelling the liquid film by using a second organic solvent, and dissolving out the first organic solvent to form pores, so as to prepare a porous gel-state film; and stretching the porous gel-state membrane and then placing the membrane in a solvent to stabilize the structure and the shape so as to prepare the polymer-based membrane. The prepared battery diaphragm does not generate thermal shrinkage, and can effectively prevent gas from shuttling between electrodes. The invention also provides a battery diaphragm and a battery comprising the battery diaphragm.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a battery diaphragm, a preparation method thereof, and a battery. Background technique [0002] Thermal runaway is the most destructive failure mode for batteries. Accompanied by violent reactions such as fire and explosion, the temperature of the battery can rise sharply to 400°C to 1000°C within seconds. [0003] As one of the key materials of the battery, the separator's basic function is to isolate the positive and negative electrodes, provide ion transmission channels, prevent short circuits in the battery, and ensure battery safety. At present, the leading product in the diaphragm market is the microporous diaphragm made of polyolefin. However, due to its low melting point (only 136°C for polyethylene and 165°C for polypropylene), it has severe heat shrinkage characteristics. This feature will lead to a smaller diaphragm area, which can easily cause a short circuit in t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/403H01M50/417H01M50/423H01M50/426H01M50/446H01M50/449H01M50/414H01M10/0525H01M10/42
CPCH01M10/0525H01M10/4235Y02E60/10
Inventor 何向明宋有志
Owner TSINGHUA UNIV
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