Diaphragm for lithium ion battery as well as preparation method and application of diaphragm

A technology for lithium-ion batteries and diaphragms, applied in the field of diaphragms for lithium-ion batteries and their preparation, can solve the problems of complex diaphragm preparation process, low diaphragm rupture temperature, and safety risks, so as to improve electrochemical performance and interface performance , the effect of improving safety

Pending Publication Date: 2022-02-15
HUIZHOU LIWINON NEW ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these methods make the preparation process of the separator more complicated, and the membrane rupture temperature of the modified membrane is still low. When the temperature reaches 130 ° C, the membrane still has the risk of membrane rupture, resulting in contact between the positive and negative electrodes and the formation of an internal short circuit. , causing the battery to catch fire or explode, posing a safety risk

Method used

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  • Diaphragm for lithium ion battery as well as preparation method and application of diaphragm
  • Diaphragm for lithium ion battery as well as preparation method and application of diaphragm
  • Diaphragm for lithium ion battery as well as preparation method and application of diaphragm

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preparation example Construction

[0038] The second aspect of the present invention is to provide the preparation method of the diaphragm, comprising the following steps:

[0039] S1, mixing cellulose with solvent water and ball milling to obtain a nanocellulose solution;

[0040] S2. Mixing and stirring the polymer microspheres and the nanocellulose solution to obtain a mixed solution, wherein the mass ratio of the nanocellulose to the polymer microspheres is 6:4 to 8.5:1.5;

[0041] S3. The mixed solution is freeze-dried and rolled to obtain a separator for a lithium-ion battery.

[0042] Due to the viscosity problem of the nanocellulose solution, the total solid content of the slurry designed by this preparation method is 5-15%. On the one hand, it can avoid the low solid content and it is difficult to meet the coating thickness requirement, and on the other hand, it can avoid the high solid content. This leads to the problems of high viscosity, poor leveling of coating slurry, and uneven film surface.

...

Embodiment 1

[0054] A separator for a lithium ion battery, comprising nanocellulose and polymer microspheres with a mass ratio of 6:4 to 8.5:1.5, wherein the particle diameter of the polymer microspheres is 0.1 to 3 μm, and the polymer microspheres are The melting point of the sphere is 100-125 DEG C; the nanocellulose and polymer microspheres are prepared by freeze-drying technology to obtain a separator for lithium ion batteries.

[0055] Specifically, the raw material used in the nanocellulose is wood nanocellulose, the raw material of the polymer microsphere is polyethylene microwax emulsion (solid content is 20%), the total solid content of the diaphragm slurry is 10%, and the configuration is 100g The slurry, the specific preparation method is:

[0056] 1) Take an appropriate amount of wood pulp board, use deionized water and ethanol to ultrasonically clean it three times, and after drying, grind it into coarse fibers with a pulverizer. The mass ratio is 1:50. Take the crude fibers a...

Embodiment 2

[0060] Different from Example 1 is the solid content of the polyethylene micro-wax emulsion, the solid content is 5%, that is, according to the actual solid content ratio in the liquid, lignonanocellulose solution: polyethylene micro-wax emulsion: wetting agent: poly The mass ratio of the acrylic glue is 6.93:0.375:0.03:0.04.

[0061] The rest are the same as in Embodiment 1, and will not be repeated here.

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Abstract

The invention provides a diaphragm for a lithium ion battery, the diaphragm comprises nanocellulose and polymer microspheres according to a mass ratio of 6: 4-8.5: 1.5, the particle size of the polymer microspheres is 0.1-3 [mu] m, and the melting point of the polymer microspheres is 100-125 DEG C; and the nano cellulose and the polymer microspheres are prepared into the diaphragm for the lithium ion battery through a freeze-drying technology. Compared with the existing diaphragm, the diaphragm provided by the invention has the advantages of high wettability, high liquid absorption rate and high thermal stability, also has a self-hole-closing function, and can effectively improve the electrochemical performance and safety performance of the battery.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to a separator for lithium ion batteries, a preparation method and application thereof. Background technique [0002] At present, polyolefin separators have the advantages of strong electrochemical stability and high mechanical strength and are widely used in commercial lithium-ion battery products. However, due to the low polarity of the polyolefin material, it has poor wettability to the electrolyte, low liquid retention capacity, and poor interface performance; and the polyolefin material itself has a low melting point, resulting in poor thermal stability of this type of separator. [0003] At present, methods such as ceramic coating on polyolefin separators can effectively improve the electrolyte wettability and thermal stability of the separator. However, these methods make the preparation process of the separator more complicated, and the membrane rupture temperature of the m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/40H01M50/403H01M50/44H01M50/443H01M10/0525
CPCH01M50/40H01M50/403H01M50/44H01M50/443H01M10/0525Y02E60/10
Inventor 刘家辉彭丹项海标陈杰杨山
Owner HUIZHOU LIWINON NEW ENERGY TECH CO LTD
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