Preparation method of pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm

文档序号：106955 发布日期：2021-10-15 浏览：11次中文

阅读说明：本技术 一种致孔剂调控微纳米多孔结构芳纶纳米纤维基电池隔膜的制备方法 (Preparation method of pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm ) 是由张美云李卫卫杨斌谭蕉君宋顺喜聂景怡王琳丁雪瑶于 2021-07-09 设计创作，主要内容包括：本发明公开了一种致孔剂调控微纳米多孔结构芳纶纳米纤维基电池隔膜的制备方法,将对位芳纶纤维、二甲基亚砜、氢氧化钾和去离子水混合搅拌,制备对位芳纶纳米纤维溶液,然后加入去离子水进行质子化还原,在真空抽滤下用无水乙醇和去离子水进行多次洗涤,然后分散在去离子水中,加入致孔剂,然后进行超声处理,并搅拌,采用真空辅助过滤和层层自组装方式进行抽滤,运用溶剂化处理方式除去致孔剂,最后干燥,得到微纳米多孔结构芳纶纳米纤维基电池隔膜。本发明在ANFs隔膜制备过程中通过添加致孔剂对ANFs膜的孔隙结构进行调控,产生微纳米级孔结构,使得ANFs膜在电池隔膜领域具有广阔的应用前景。(The invention discloses a preparation method of a micro-nano porous structure aramid fiber nanofiber-based battery diaphragm regulated by a pore-forming agent. According to the invention, the pore structure of the ANFs membrane is regulated and controlled by adding the pore-forming agent in the preparation process of the ANFs membrane, so that a micro-nano pore structure is generated, and the ANFs membrane has a wide application prospect in the field of battery membranes.)

1. A preparation method of a pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm is characterized by comprising the following steps:

the method comprises the following steps: mixing and stirring para-aramid fiber, dimethyl sulfoxide, potassium hydroxide and deionized water to prepare a para-aramid nanofiber solution A with the mass concentration of 0.1-0.3%;

step two: adding deionized water into the para-aramid nano-fiber solution A obtained in the step one for protonation reduction, respectively washing the solution for multiple times by using absolute ethyl alcohol and deionized water under vacuum filtration, and dispersing the solution in the deionized water to obtain a para-aramid nano-fiber solution B;

step three: adding a pore-foaming agent into the para-aramid nano-fiber solution B obtained in the step two, then carrying out ultrasonic treatment to uniformly disperse the pore-foaming agent in the para-aramid nano-fiber solution B, and stirring to obtain a para-aramid nano-fiber solution C;

step four: carrying out suction filtration on the uniformly dispersed para-aramid nano-fiber solution C by adopting a vacuum auxiliary filtration and layer-by-layer self-assembly mode to prepare an ANFs membrane;

step five: removing the pore-foaming agent added in the ANFs film;

step six: and D, drying the ANFs membrane obtained in the fifth step to obtain the micro-nano porous structure aramid fiber nanofiber-based battery diaphragm.

2. The preparation method of the pore-foaming agent regulated and controlled micro-nano porous structure aramid nanofiber-based battery diaphragm according to claim 1, wherein in the second step, the volume ratio of the para-aramid nanofiber solution A to deionized water is 1:2 during protonation reduction.

3. The preparation method of the aramid nanofiber-based battery diaphragm with the micro-nano porous structure regulated and controlled by the pore-foaming agent according to claim 1, wherein the pore-foaming agent used in the third step is polyvinylpyrrolidone, ammonium bicarbonate or polyethylene glycol-1000.

4. The preparation method of the aramid nanofiber-based battery diaphragm with the micro-nano porous structure regulated and controlled by the pore-foaming agent according to claim 3, wherein when the pore-foaming agent is polyvinylpyrrolidone, the amount of the pore-foaming agent is 5% -25% of the mass of the para-aramid nanofiber; when the pore-foaming agent adopts ammonium bicarbonate, the dosage is 3-10% of the mass of the para-aramid nano-fiber; when the pore-foaming agent adopts polyethylene glycol-1000, the dosage is 3-10% of the mass of the para-aramid nano-fiber.

5. The preparation method of the aramid fiber nanofiber-based battery diaphragm with the micro-nano porous structure regulated and controlled by the pore-foaming agent according to claim 3, wherein the step five is specifically as follows: when the pore-foaming agent is polyvinylpyrrolidone, soaking with dichloromethane for 4 h; when the pore-forming agent is ammonium bicarbonate, the ammonium bicarbonate is heated and decomposed to generate carbon dioxide through heating treatment and then removed; when the pore-forming agent is polyethylene glycol 1000, soaking in 20% by volume of N, N-dimethylformamide for 7min, and heating in 70 deg.C water bath for 3 h.

6. The preparation method of the aramid nanofiber-based battery diaphragm with the micro-nano porous structure regulated and controlled by the pore-foaming agent according to claim 1, wherein in the third step, the ultrasonic power is 90W, and the ultrasonic time is 30 min.

7. The preparation method of the aramid nanofiber-based battery diaphragm with the micro-nano porous structure regulated and controlled by the pore-foaming agent according to claim 1, wherein in the sixth step, the drying temperature is 105 ℃ and the drying time is 10 min.

8. The preparation method of the pore-foaming agent regulated and controlled micro-nano porous structure aramid nanofiber-based battery diaphragm according to claim 1, wherein the thickness of the micro-nano porous structure aramid nanofiber-based battery diaphragm obtained in the sixth step is 20-45 μm.

Technical Field

The invention belongs to the field of battery diaphragms, and particularly relates to a preparation method of a micro-nano porous structure aramid fiber nanofiber-based battery diaphragm regulated by a pore-foaming agent.

Background

The battery diaphragm is one of four major components of the battery, and plays an important role in the safety performance and the electrochemical performance of the battery. However, the current commercial battery separator has poor heat resistance stability and lyophilic property, and is easy to shrink at high temperature or high current density to cause short circuit of the battery, so that the battery separator has a great safety risk. Therefore, it is of great significance to research and develop some novel high-performance battery separator materials to meet practical needs.

The para-Aramid nano-fibers (ANFs) as a nano-grade material newly developed in recent years have a unique nano-scale structure (the diameter is 3-30nm, and the length can reach 10 mu m at most), a large length-diameter ratio and a large specific surface area, and are endowed with excellent characteristics of the nano-grade material. The ANFs have the advantages of high strength, high temperature resistance, transparency, good flexibility, obvious Z-direction hierarchical structure and the like, and have huge application prospects in the field of battery diaphragms. According to the invention patent CN11158480A, aramid nanofibers are deposited on the surface of the modified PVDF-HFP diaphragm to enhance the adhesive force between the aramid fibers and the surface of the base film, so that the diaphragm with high mechanical strength, good high temperature resistance and excellent electrochemical performance is prepared. According to the invention, the patent CN111370625A is that aramid fiber, a cosolvent, an oily auxiliary agent and a pore-forming agent are dissolved at 60-100 ℃ to prepare a coating liquid, the coating liquid is coated on one side or two sides of a diaphragm substrate, the coating liquid is immersed into a coagulating bath consisting of a second solvent and water for phase conversion for 1-3 min, then the coating liquid is immersed into pure water to remove the redundant solvent, and the finished product lithium ion battery diaphragm is obtained after drying.

However, there are few reports on the use of pure ANFs as battery separators. Because the hydrogen bond effort is strong between the aramid fiber nanofiber for the structure is compact between the ANFs membrane, can influence lithium ion transmission speed when directly being applied to the battery diaphragm with the aramid fiber ANFs membrane, and then influences the charge-discharge performance of battery, therefore this patent uses the aramid fiber nanofiber as the raw materials of preparation battery diaphragm.

Disclosure of Invention

The invention aims to provide a preparation method of a pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm, so as to overcome the defect that an aramid fiber nanofiber membrane serving as a battery diaphragm is too compact in structure and affects Li⁺A defect in transmission. According to the invention, the pore structure of the ANFs membrane is regulated and controlled by adding the pore-forming agent in the preparation process of the ANFs membrane, so that a micro-nano pore structure is generated, and the ANFs membrane has a wide application prospect in the field of battery membranes.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm comprises the following steps:

step five: removing the pore-foaming agent added in the ANFs film;

step six: and D, drying the ANFs membrane obtained in the fifth step to obtain the micro-nano porous structure aramid fiber nanofiber-based battery diaphragm.

Further, in the second step, when protonation reduction is carried out, the volume ratio of the para-aramid nano-fiber solution A to the deionized water is 1: 2.

Further, the pore-foaming agent used in the third step is polyvinylpyrrolidone, ammonium bicarbonate or polyethylene glycol-1000.

Further, when the pore-foaming agent adopts polyvinylpyrrolidone, the amount of the pore-foaming agent is 5-25% of the mass of the para-aramid nano-fiber; when the pore-foaming agent adopts ammonium bicarbonate, the dosage is 3-10% of the mass of the para-aramid nano-fiber; when the pore-foaming agent adopts polyethylene glycol-1000, the dosage is 3-10% of the mass of the para-aramid nano-fiber.

Further, the fifth step is specifically: when the pore-foaming agent is polyvinylpyrrolidone, soaking with dichloromethane for 4 h; when the pore-forming agent is ammonium bicarbonate, the ammonium bicarbonate is heated and decomposed to generate carbon dioxide through heating treatment and then removed; when the pore-forming agent is polyethylene glycol 1000, soaking in 20% by volume of N, N-dimethylformamide for 7min, and heating in 70 deg.C water bath for 3 h.

Furthermore, in the third step, the ultrasonic power is 90W, and the ultrasonic time is 30 min.

Further, in the sixth step, the drying temperature is 105 ℃, and the drying time is 10 min.

Further, the thickness of the micro-nano porous structure aramid fiber nanofiber-based battery diaphragm obtained in the sixth step is 20-45 microns.

Compared with the prior art, the invention has the following beneficial technical effects:

according to the invention, in the preparation process of the aramid nano-fiber membrane, the pore-foaming agent is added into the system, the pore size of the aramid nano-fiber membrane is adjusted, and the aramid nano-fiber-based battery membrane with a micro-nano structure is prepared, so that a novel method is provided for preparing a novel high-performance battery membrane.

In the preparation process of the aramid nano-fiber membrane, the pore-forming agent is used for hindering the limited combination of intermolecular hydrogen bonds, and the prepared aramid nano-fiber membrane is subjected to different treatment modes to remove the pore-forming agent added in the system, so that the battery diaphragm material with uniform pore size is produced. The pore structure and the pore size are regulated and controlled by the pore-forming agent, so that the problem that the normal use of the diaphragm is influenced due to the excessive densification of the ANFs membrane structure is solved, the service life of the battery diaphragm is greatly prolonged, the grade of a product is improved, a new method and a theoretical basis are provided for the preparation of a high-performance battery diaphragm material, the long-term charge-discharge cycle use of lithium ion batteries and lithium sulfur batteries can be met, the stability of the diaphragm is improved, and the pore-forming agent has important significance for the development of the field of new energy automobiles.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

Fig. 1 is an SEM image of an aramid nanofiber-based battery diaphragm obtained by pore-forming with ammonium bicarbonate in example 8 of the present invention, where (a) is an SEM image of a pure ANFs film, (b) is an enlarged view of the pure ANFs film, (c) is an SEM image of the ANFs film after ammonium bicarbonate treatment, and (d) is an enlarged view of the ANFs film after ammonium bicarbonate treatment.

Detailed Description

The invention is described in further detail below:

a preparation method of a pore-foaming agent regulated and controlled micro-nano porous structure aramid fiber nanofiber-based battery diaphragm comprises the following steps:

step (1): uniformly mixing para-aramid fiber, potassium hydroxide, dimethyl sulfoxide and deionized water according to a certain proportion at room temperature, stirring at the room temperature at the stirring speed of 1500rpm for 4 hours to prepare a para-aramid nanofiber solution; wherein the mass ratio of the para-aramid fiber to the potassium hydroxide is 1:1.5, the volume ratio of the dimethyl sulfoxide to the deionized water is 25:1, and the diameter and the length of the para-aramid nanofiber are 8-15 mm and 3-8 microns respectively;

step (2): the para-aramid nano-fiber solution in a DMSO/KOH system is stirred to give a certain shearing force, deionized water is injected into the system by an injector for protonation reduction, and the solution is dispersed in DMSO/KOH/H₂Washing a para-aramid nano-fiber solution in an O mixed system to be colloidal by using absolute ethyl alcohol and deionized water respectively under vacuum filtration, wherein the volume ratio of the deionized water used for protonation reduction to the para-aramid nano-fiber solution is 2:1, the washing times by using the absolute ethyl alcohol and the deionized water are respectively 4 times, and the volume of the deionized water used for dispersing the para-aramid nano-fiber solution is 300 mL;

and (3): adding a pore-foaming agent into the para-aramid nano-fiber solution obtained in the step (2), then carrying out ultrasonic treatment in an ultrasonic dispersion machine to ensure that the pore-foaming agent is uniformly dispersed in a para-aramid nano-fiber solution system, and uniformly dispersing the aramid nano-fiber by magnetic stirring, wherein the pore-foaming agent is polyvinylpyrrolidone (PVP) with the use amount of 5-25 percent and ammonium bicarbonate (NH)₄HCO₃) The dosage is 3 to 10 percent, the dosage of polyethylene glycol-1000 (PEG-1000) is 3 to 10 percent, the ultrasonic power is 90W, the ultrasonic time is 30min, and the time for dispersing the para-aramid nano-fiber solution by magnetic stirring is 12 h;

and (4): carrying out suction filtration on the uniformly dispersed para-aramid nano-fiber solution obtained in the step (3) by adopting a vacuum auxiliary filtration and layer-by-layer self-assembly mode to prepare an aramid nano-fiber membrane;

and (5): removing a pore-foaming agent added in the aramid nano-fiber membrane by using a solvation treatment mode, wherein when the pore-foaming agent is polyvinylpyrrolidone (PVP), the pore-foaming agent is soaked by dichloromethane for 4 h; the pore-forming agent is ammonium bicarbonate (NH)₄HCO₃) When the ammonium bicarbonate is heated and decomposed to generate carbon dioxide to generate gas for removal; when the pore-forming agent is polyethylene glycol 1000, soaking in 20% N, N-dimethylformamide for 7min, and decocting in 70 deg.C water bath for 3 hr.

And (6): and (3) drying the aramid fiber nanofiber membrane obtained in the step (5) to obtain the micro-nano porous structure aramid fiber nanofiber-based battery diaphragm, wherein the drying temperature is 105 ℃, the drying time is 10min, and the thickness of the aramid fiber nanofiber membrane is 20-45 mu m.

The present invention will be described in detail with reference to examples. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The following detailed description is illustrative of the embodiments and is intended to provide further details of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention.

Example 1

Step (1): taking 0.1g of para-aramid fiber, 0.15g of potassium hydroxide, 100ml of dimethyl sulfoxide and 4ml of deionized water, and carrying out stirring reaction at room temperature, wherein the stirring rotation speed is 1500rpm, and the stirring reaction time is 4 hours, so as to obtain a uniform dark red aramid nanofiber solution;

step (2): the para-aramid nano-fiber solution obtained in the step (1) is added with a certain shearing force under the action of magnetic stirring, 200ml of deionized water is injected into the system by an injector for protonation reduction, and the solution is dispersed in DMSO/KOH/H₂Washing the para-aramid nano-fiber solution in the O mixed system with absolute ethyl alcohol and deionized water respectively for 4 times under vacuum filtration until the solution is colloidal, and dispersing the solution with 300ml of deionized water;

and (3): adding 0.005g (accounting for 5% of the mass of the aramid fiber) of polyvinylpyrrolidone into the aramid fiber nanofiber solution obtained in the step (2), then carrying out ultrasonic treatment in a 90W ultrasonic dispersion machine for 30min, and after the ultrasonic treatment is finished, placing the aramid fiber nanofiber solution in a magnetic stirrer to be stirred and dispersed for 12 h;