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Method for modifying polyolefin lithium-ion battery separator

A polyolefin diaphragm and modification technology, which is applied in the direction of secondary batteries, battery components, circuits, etc., can solve the problems of not introducing heat-resistant materials and increasing the resistance of the diaphragm, so as to increase the surface roughness and shrinkage of the film Effect of reducing and increasing surface energy

Active Publication Date: 2019-07-12
江苏北星新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above methods of modifying the diaphragm all use strong polar and volatile organic solvents, and there are potential safety hazards in the process of curing the slurry; and when the thickness of the coating layer is large, the impedance of the diaphragm will also increase.
Using water as a solvent, Zhang et al. used tannic acid and polyethyleneimine to construct an ultra-thin lyophilic modification layer on the surface of a polypropylene separator by layer-by-layer self-assembly method. The contact angle of the separator to the electrolyte was about 10°. There is still a capacity retention rate of 35% (Electrochim.Acta, 2018, 275: 25-31), but this method does not introduce heat-resistant materials, and the thermal stability of the modified polyolefin separator needs to be further improved

Method used

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  • Method for modifying polyolefin lithium-ion battery separator
  • Method for modifying polyolefin lithium-ion battery separator
  • Method for modifying polyolefin lithium-ion battery separator

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 1) Pretreatment of the diaphragm

[0022] Corona treatment was performed on the PE separator fully washed with deionized water and ethanol, with a power of 0.1W and a treatment time of 20s to make the surface negatively charged.

[0023] 2) In situ self-assembly to construct organic-inorganic hybrid composite layer

[0024] as attached figure 1 As shown, soak the PE diaphragm pretreated in step 1) in chitosan-calcium chloride solution (chitosan concentration 0.1g / L, calcium chloride concentration 0.075mol / L) for 20min, take it out and wash it, and then Soak in polyacrylic acid-sodium silicate solution (polyacrylic acid concentration 0.1g / L, sodium silicate concentration 0.075mol / L) for 20min, take it out and wash it. An organic / inorganic hybrid composite layer is constructed on the surface of the PE separator.

[0025] 3) Post-treatment of modified diaphragm

[0026] The PE separator containing the organic / inorganic hybrid composite layer obtained in step 2) was fur...

Embodiment 2

[0028] 1) Pretreatment of the diaphragm

[0029] Corona treatment was performed on the PE separator fully washed with deionized water and ethanol, with a power of 1W and a treatment time of 6s to make its surface negatively charged.

[0030] 2) In situ self-assembly to construct organic-inorganic hybrid composite layer

[0031] as attached figure 1 As shown, soak the PE diaphragm pretreated in step 1) in chitosan-calcium chloride solution (chitosan concentration 1g / L, calcium chloride concentration 0.04mol / L) for 20min, take it out and wash it, and then dip it Put it in polyacrylic acid-sodium silicate solution (polyacrylic acid concentration 1g / L, sodium silicate concentration 0.04mol / L) for 20min, take it out and wash it. Step 2) was repeated, and two layers of organic / inorganic hybrid composite layers were constructed on the surface of the PE separator.

[0032] 3) Post-treatment of modified diaphragm

[0033] The PE separator containing the organic / inorganic hybrid com...

Embodiment 3

[0035] 1) Pretreatment of the diaphragm

[0036] The PP separator fully washed with deionized water and ethanol was subjected to corona treatment with a power of 1.5W and a treatment time of 8s to make the surface negatively charged.

[0037] 2) In situ self-assembly to construct organic-inorganic hybrid composite layer

[0038] as attached figure 1 As shown, soak the PP diaphragm pretreated in step 1) in chitosan-polyacrylic acid solution (chitosan concentration 0.5g / L, calcium chloride concentration 0.09mol / L) for 20min, take it out and wash it, and then dip it Put it in polyacrylic acid-sodium silicate solution (polyacrylic acid concentration 0.5g / L, sodium silicate concentration 0.09mol / L) for 20min, take it out and wash it. An organic / inorganic hybrid composite layer is constructed on the surface of the PP separator.

[0039] 3) Post-treatment of modified diaphragm

[0040] The PP separator containing the organic / inorganic hybrid composite layer obtained in step 2) wa...

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Abstract

The invention relates to a method for modifying a polyolefin lithium-ion battery separator, belonging to the field of lithium-ion battery separators. The method comprises the steps of: the step 1) immersing a pretreated polyolefin separator into a polycation electrolyte solution containing a calcium salt for 10-100 min, taking out and cleaning the pretreated polyolefin separator, then immersing the pretreated polyolefin separator into a polyanion electrolyte solution containing sodium silicate for 10-100 min, so that Ca2+ in the calcium salt and SiO32- ions of the sodium silicate react in situwhile the polycation electrolyte and the polyanion electrolyte are assembled according to electrostatic action to generate calcium silicate inorganic nano particles in the polyelectrolyte; repeatingthe steps for 1-6 times, and constructing organic / inorganic hybrid composite layers with different assembly layer numbers on the surface of the polyolefin porous separator; and then drying the organic / inorganic hybrid composite layers to finish the steps. The separator has better thermal stability and charge-discharge stability.

Description

technical field [0001] The invention relates to a method for modifying a lithium-ion battery diaphragm, in particular to an organic-inorganic hybrid modification method for a polyolefin diaphragm, and belongs to the field of lithium-ion battery diaphragms. Background technique [0002] As a new type of secondary battery, lithium-ion batteries are widely used in portable electronic equipment, aerospace medical treatment, new energy vehicles and other fields due to their high energy density, long service life, and no memory effect. Lithium-ion batteries are composed of four parts: positive electrode, separator, electrolyte and negative electrode. As one of the key components of lithium-ion batteries, the separator has electronic insulation, which can prevent the direct contact between the positive and negative electrodes of the lithium battery and avoid the internal short circuit of the battery; at the same time, the separator must also have ion conductivity to provide mass tr...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M10/0525H01M50/403
CPCH01M10/0525H01M50/403Y02E60/10
Inventor 秦振平王峰肖波杨蕊李钒郭红霞赵耀
Owner 江苏北星新材料科技有限公司
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