Battery separator, preparation method and polyimide porous membrane impregnation equipment

文档序号：552897 发布日期：2021-05-14 浏览：31次中文

阅读说明：本技术 一种电池隔膜、制备方法和聚酰亚胺多孔膜的浸渍设备 (Battery separator, preparation method and polyimide porous membrane impregnation equipment ) 是由李茹齐学礼张铭霞周长灵聂永俊何子阳孙淑敏岳双双于 2021-01-13 设计创作，主要内容包括：本发明公开了一种电池隔膜,包括聚烯烃多孔膜层和聚酰亚胺多孔膜层,其特征在于,所述聚酰亚胺多孔膜层为浸渍后的聚酰亚胺基膜,所述聚酰亚胺多孔膜层的刺穿强度为0.68-3N,所述多孔隔膜的MD方向拉伸强度大于聚酰亚胺基膜的2倍；还包括位于聚酰亚胺多孔膜层和聚烯烃多孔膜层之间的氧化铝涂层、粘合剂层,所述聚烯烃多孔膜层和聚酰亚胺多孔膜层通过氧化铝涂层、粘合剂层复合。(The invention discloses a battery diaphragm, which comprises a polyolefin porous membrane layer and a polyimide porous membrane layer, and is characterized in that the polyimide porous membrane layer is a polyimide base membrane after being impregnated, the puncture strength of the polyimide porous membrane layer is 0.68-3N, and the MD (machine direction) tensile strength of the porous diaphragm is 2 times greater than that of the polyimide base membrane; the composite film further comprises an aluminum oxide coating and an adhesive layer, wherein the aluminum oxide coating and the adhesive layer are located between the polyimide porous film layer and the polyolefin porous film layer, and the polyolefin porous film layer and the polyimide porous film layer are compounded through the aluminum oxide coating and the adhesive layer.)

1. A battery diaphragm comprises a polyolefin porous film layer and a polyimide porous film layer, and is characterized in that,

the polyimide porous membrane layer comprises a polyimide base membrane and an impregnation layer coated outside the polyimide base membrane;

the puncture strength of the polyimide porous membrane layer is 0.68-3N, and the MD (machine direction) tensile strength of the porous membrane is 2 times greater than that of the polyimide base membrane;

the composite film further comprises an aluminum oxide coating and an adhesive layer, wherein the aluminum oxide coating and the adhesive layer are located between the polyimide porous film layer and the polyolefin porous film layer, and the polyolefin porous film layer and the polyimide porous film layer are compounded through the aluminum oxide coating and the adhesive layer.

2. The battery separator of claim 1 wherein said impregnation layer comprises a polyimide resin or a phenolic resin or an aramid resin.

3. The battery separator as claimed in claim 1, wherein the polyimide porous membrane layer has a gas permeability of 15-120s/100mL, preferably 30-80s/100 mL.

4. The battery separator of claim 1, wherein the polyimide porous membrane layer has a MD tensile strength greater than 70MPa, and the porous separator has a TD tensile strength greater than 50 MPa.

5. The battery separator of claim 1 wherein said alumina coating comprises, in parts by weight: 25-40 parts of water, 25-40 parts of alumina powder, 0.3-1.2 parts of emulsifier, 0.2-0.4 part of thickener and 5-10 parts of binder.

6. The battery separator of claim 1 wherein said adhesive has a thickness of 0.3 to 0.8 μm.

7. The impregnation equipment for the polyimide porous membrane is characterized by comprising a spraying component, an impregnation tank and after-treatment equipment which are sequentially arranged;

a fixing frame for fixing the polyimide base film;

the conveying component is used for transferring the fixing frame among the spraying component, the dipping tank and the after-finishing equipment;

the spraying assembly comprises an upper spraying head and a lower spraying head which are oppositely arranged, a spraying channel is formed between the upper spraying head and the lower spraying head, the lower spraying head is arranged in a liquid collecting tank, and the liquid collecting tank is communicated with the impregnation tank;

the after-finishing equipment comprises a conveyor belt and a coating roller group.

8. The impregnation apparatus for a polyimide porous membrane according to claim 7, wherein the conveyance assembly comprises: a transfer trolley and a transfer track;

the conveying track comprises a first horizontal track positioned above the spraying assembly, a second horizontal track positioned above the dipping tank, a third horizontal track positioned above the after-treatment equipment and an inclined track connecting the first horizontal track, the second horizontal track and the third horizontal track;

the height of the second horizontal rail is smaller than the height of the first horizontal rail and the height of the third horizontal rail.

9. The impregnation apparatus for the polyimide porous membrane according to claim 7, wherein the transfer cart comprises two support shafts which are oppositely arranged, wherein the two ends of the support shafts are connected with the traveling wheels, the two support shafts are connected through a connecting rod, and two cross universal joints are arranged in the middle of the connecting rod.

10. A preparation method of a battery diaphragm is characterized by comprising the following steps:

spraying a resin solution on the surface of the polyimide base film;

soaking a polyimide base film in a resin solution, wherein the mass fraction of resin in the resin solution is 3-30%, and the preferable mass fraction is 5-15%;

uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 20-50 ℃, and curing at 160-300 ℃ to obtain a polyimide porous membrane layer;

coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

coating an adhesive on the surface of one side of the polyolefin film, and thermally compounding the surface containing the adhesive and the surface of the polyimide porous film layer containing the alumina coating.

Technical Field

The invention relates to the technical field of composite materials, in particular to a battery diaphragm, a preparation method and polyimide porous membrane impregnation equipment.

Background

The separator plays a crucial role in the safety of the lithium ion secondary battery. When the temperature in the lithium ion battery is out of control due to short circuit, overcharge and the like, the polymer diaphragm is closed at a high temperature to interrupt the current, but when the temperature is continuously increased and exceeds the heat-resistant temperature of the diaphragm, the diaphragm can be fused, the battery is short-circuited, and the safety accident of the battery is caused.

At present, the commercialized diaphragm is mainly a polyolefin microporous membrane, has the advantages of excellent mechanical property, uniform aperture and the like, but the melting temperature of the diaphragm is lower than 165 ℃, and the diaphragm is broken when the external temperature of the battery is too high or the battery is accidentally impacted, so that safety accidents are caused. A diaphragm with higher heat-resistant temperature is required to be found, a scheme of using a polyimide diaphragm to replace a polyolefin microporous membrane appears in the prior art, but compared with the polyolefin diaphragm, the polyimide diaphragm has no closed pore performance, a battery has a large amount of heat release problems, and the diaphragm can be burnt out instantly; the separator is easily pierced and has low assembly strength, and in addition, the battery is easily short-circuited when the external temperature of the battery is excessively high or the battery is accidentally bumped, thereby causing a battery safety accident and threatening the safety performance of the battery.

Disclosure of Invention

In order to solve the technical problems, the invention provides a battery diaphragm, a preparation method and an impregnation device of a polyimide porous membrane.

According to one aspect of the present invention, there is provided a porous membrane layer comprising a polyolefin porous membrane layer and a polyimide porous membrane layer;

the polyimide porous membrane layer comprises a polyimide base membrane and an impregnation layer coated outside the polyimide base membrane;

Further, the impregnation layer comprises polyimide resin or phenolic resin or aramid resin.

Further, the air permeability of the polyimide porous membrane layer is 15-120s/100mL, and preferably 30-80s/100 mL.

Further, the tensile strength of the polyimide porous membrane layer in the MD direction is more than 70MPa, and the tensile strength of the porous membrane in the TD direction is more than 50 MPa.

Further, the alumina coating comprises the following components in parts by weight: 25-40 parts of water, 25-40 parts of alumina powder, 0.3-1.2 parts of emulsifier, 0.2-0.4 part of thickener and 5-10 parts of binder.

Further, the thickness of the adhesive is 0.3-0.8 μm.

Compared with the prior art, the invention has the beneficial effects that:

1. the composite membrane is formed by thermally compounding a polyimide membrane and a polyolefin porous membrane, the high temperature resistance of polyimide and the closed pore temperature, the mechanical strength and the puncture strength of the polyolefin porous membrane are kept, the polyimide base membrane is coated with an impregnation layer, the puncture strength and the MD (machine direction) tensile strength of the polyimide porous membrane are improved, the composite membrane has good mechanical performance, and the safety of a lithium battery is greatly improved.

According to another aspect of the invention, the impregnation equipment for the polyimide porous membrane comprises a spraying component, an impregnation tank and after-treatment equipment which are sequentially arranged;

a fixing frame for fixing the polyimide base film;

the conveying component is used for transferring the fixing frame among the spraying component, the dipping tank and the after-finishing equipment;

the after-finishing equipment comprises a conveyor belt and a coating roller group.

Further, the transfer assembly includes: a transfer trolley and a transfer track;

the height of the second horizontal rail is smaller than the height of the first horizontal rail and the height of the third horizontal rail.

Furthermore, the conveying trolley comprises two supporting shafts which are oppositely arranged, walking wheels are connected to the two ends of each supporting shaft, the two supporting shafts are connected through a connecting rod, and two cross universal joints are arranged in the middle of the connecting rod.

Compared with the prior art, the impregnation equipment for the polyimide porous membrane has the beneficial effects that:

1. can once accomplish spray, aftertreatment process, aftertreatment equipment includes conveyer belt and coating roller set, can be even with the steeping liquor coating on polyimide base film surface, prevents that the local thickness that the steeping liquor coating inequality appears too big, and the gas permeability of polyimide porous membrane is influenced to the steeping liquor is too thick.

2. The two support shafts are connected through the connecting rod, two cross universal energy-saving devices are arranged in the middle of the connecting rod, and the trolley can be transferred between the first horizontal rail, the second horizontal rail, the third horizontal rail and the inclined rail.

According to another aspect of the present invention, there is provided a battery separator preparation method, including the steps of:

spraying a resin solution on the surface of the polyimide base film;

dipping a polyimide base film in a resin solution;

uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 20-50 ℃, and curing at 160-300 ℃ to obtain a polyimide porous membrane layer;

coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

According to one aspect of the present invention, there is provided a battery separator preparation method,

spraying a resin solution on the surface of the polyimide base film;

soaking a polyimide base film in a resin solution, wherein the mass fraction of resin in the resin solution is 3-30%, and the preferable mass fraction is 5-15%;

uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 20-50 ℃, and curing at 160-300 ℃ to obtain a polyimide porous membrane layer;

coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

Compared with the prior art, the preparation method of the battery diaphragm has the beneficial effects that: resin solution is sprayed on the surface of the polyimide base membrane before impregnation, so that the resin solution can fully infiltrate pore channels, the pore channel structure of the non-woven fabric membrane is improved, the problem of pore blocking caused by direct impregnation is avoided, and finally the air permeability of the polyimide porous membrane layer is 15-120s/l00 mL. The alumina layer can improve the pore structure, improve the binding force of the polyimide porous film layer and the polyolefin film layer, improve the infiltration capacity and the liquid retention performance of the diaphragm and an electrolyte solution, and improve the ionic conductivity.

Drawings

FIG. 1 is a schematic structural view of the present invention;

fig. 2 is a schematic structural view of the transfer cart.

The reference numbers shown in the figures: 1. a spray assembly; 11-upper spray header; 12-lower shower head; 13-a liquid collecting tank; 2-dipping tank; 3-after-finishing equipment; 31-a conveyor belt; 32-a set of coating rollers; 4-a fixing frame; 5, conveying the trolley; 51-a support shaft; 52-road wheels; 53-connecting rods; 54-a cross universal joint; 6-a transfer track; 61-a first horizontal rail; 62-a second horizontal rail; 63-third horizontal track.

Detailed Description

In order to better understand the technical scheme of the invention, the invention is further explained by combining the drawings and the specific embodiments in the specification.

Example 1:

this example provides a battery separator comprising a polyolefin porous membrane layer and a polyimide porous membrane layer,

the polyimide porous membrane layer comprises a polyimide base membrane and an impregnation layer coated outside the polyimide base membrane, the impregnation layer comprises high-temperature-resistant reinforced resin such as polyimide resin or phenolic resin or aramid resin, and the high-temperature-resistant reinforced resin is resin with temperature resistance higher than 280 ℃. The puncture strength of the polyimide porous membrane layer is 0.68-3N, the MD tensile strength of the porous membrane is 2 times greater than that of the polyimide base membrane, in the embodiment, the MD tensile strength of the polyimide porous membrane layer is greater than 70MPa, the TD tensile strength of the porous membrane is greater than 50MPa, and the air permeability of the polyimide porous membrane layer is 30-120s/l00 mL.

the aluminum oxide coating comprises the following components in parts by weight: 200 parts of water, 100 parts of alumina powder, 0.3-1.2 parts of emulsifier, 0.2-0.4 part of thickener and 5-10 parts of binder. In this embodiment, the binder is LA133 or polyacrylate; the emulsifier is AEO-9 or OP emulsifier;

the specific formula of the alumina coating in the embodiment is as follows: 210g of water; 100g of alumina powder (D50, particle size 100-600 nm); emulsifier: AEO-92.5 g; thickening agent: sodium carboxymethylcellulose 1.0 g; adhesive: LA 13324 g.

The adhesive can be AFL adhesive, the thickness of the adhesive is 0.3-0.8 mu m, the battery diaphragm is formed by thermally compounding a polyimide film and a polyethylene porous film, the high temperature resistance of polyimide and the pore-closing temperature of the polyethylene porous film are reserved, and the penetration strength and the MD (machine direction) tensile strength of the polyimide base film are improved by an impregnation layer coated outside the polyimide base film, so that the compounded battery diaphragm has good mechanical properties, and the safety of a battery, particularly a lithium battery, can be greatly improved.

The embodiment provides a polyimide porous membrane impregnation device, which comprises a spraying component 1, an impregnation tank 2 and a post-treatment device 3 which are sequentially arranged;

the device comprises a fixing frame 4 for fixing a polyimide base film, and a conveying assembly for transferring the fixing frame 4 among a spraying assembly 1, a soaking tank 2 and an after-finishing device 3;

the spraying assembly 1 comprises an upper spraying head 11 and a lower spraying head 12 which are oppositely arranged, a spraying channel is formed between the upper spraying head 11 and the lower spraying head 12, the lower spraying head 12 is arranged in a liquid collecting tank 13, and the liquid collecting tank 13 is communicated with the impregnation tank 2; the finishing apparatus 3 includes a conveyor belt 31 and a coating roller group 32.

The transfer assembly includes: a transfer trolley 5 and a transfer rail 6;

the conveying trolley 5 comprises two support shafts 51 which are oppositely arranged, walking wheels 52 are connected to two ends of each support shaft 51, the two support shafts 51 are connected through a connecting rod 53, and two cross universal joints 54 are arranged in the middle of the connecting rod 53.

The conveying rail 6 comprises a first horizontal rail 61 positioned above the spraying assembly 1, a second horizontal rail 62 positioned above the dipping tank 2, a third horizontal rail 63 positioned above the after-treatment equipment 3 and an inclined rail connecting the first horizontal rail 61, the second horizontal rail 62 and the third horizontal rail 63;

the height of the second horizontal rail 62 is smaller than the height of the first horizontal rail 61 and the third horizontal rail 63.

As shown in fig. 1, in the present embodiment, the conveying trolley 5 is connected to the polyimide porous membrane fixing frame 4 through a chain or a rope, the polyimide porous membrane fixing frame 4 includes a hollow supporting frame, the support frame is provided with a fixing clamp for fixing the polyimide porous membrane, the polyimide porous membrane is fixed on the polyimide porous membrane fixing frame 4 during impregnation, the conveying trolley 5 is started to enter between the upper spray header 11 and the lower spray header 12 to form a spray channel, after spraying is finished, enters the dipping tank 2 through a first horizontal rail 61 and an inclined rail, two supporting shafts 51 are connected through a connecting rod 53, the middle of the connecting rod 53 is provided with two cross universal joints 54, which can facilitate the stable transfer of the trolley between the first horizontal rail 61, the second horizontal rail 62, the third horizontal rail 63 and the inclined rail, and prevent the derailment of the trolley when the trolley passes through the inclined rail. The height of the second horizontal rail 62 is smaller than the height of the first horizontal rail 61 and the height of the third horizontal rail 63, so that the polyimide porous membrane fixing frame 4 is immersed into the resin solution of the impregnation tank 2, the residence time of the polyimide porous membrane fixing frame in the impregnation tank 2 is determined according to actual needs, after impregnation is completed, the polyimide porous membrane fixing frame 4 is placed on the conveyor belt 31, the polyimide porous membrane is taken down and conveyed to the coating roller group 32 through the conveyor belt 31, the impregnation liquid on the surface of the polyimide base membrane is uniformly coated, and the phenomenon that the local thickness is too large due to uneven coating of the impregnation liquid is prevented.

This example provides a method of making the above-described battery separator,

step 1, spraying a resin solution on the surface of a polyimide base film;

step 2, soaking the polyimide base membrane in a resin solution, wherein the mass fraction of resin in the resin solution is 3-30%, preferably 5-15%, the resin content is 3-30%, partial pore channels can be filled, the pore channels cannot be blocked, and the air permeability of the cured polyimide porous membrane layer is 15-120s/100 mL;

step 3, uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 20-50 ℃, and curing at the temperature of 160-300 ℃ to obtain the polyimide porous membrane layer, specifically curing at the temperature of 260-300 ℃ when the polyimide resin is used; curing at 160-280 ℃ when the phenolic resin is used;

step 4, coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

step 5, coating an adhesive on the surface of one side of the polyolefin membrane, and carrying out thermal compounding on the surface containing the adhesive and the surface of the polyimide porous membrane layer containing the alumina coating, wherein the compounding process can adopt a plastic packaging machine (the compounding temperature is 80-120 ℃, and the compounding speed is 3-8mm/min) or hot-press compounding; resin solution is sprayed on the surface of the polyimide base membrane before impregnation, so that the resin solution can fully infiltrate pore channels, the pore channel structure of the non-woven fabric membrane is improved, the problem of pore blocking caused by direct impregnation is avoided, and finally the air permeability of the polyimide porous membrane layer is 15-120s/l00 mL. The alumina layer can improve the pore structure, improve the binding force of the polyimide porous film layer and the polyolefin film layer, improve the infiltration capacity and the liquid retention performance of the diaphragm and an electrolyte solution, and improve the ionic conductivity.

Example 2

The embodiment provides a battery diaphragm, including porous rete of polyolefin and the porous rete of polyimide, the porous rete of polyimide includes polyimide base film and cladding in the outside impregnation layer of polyimide base film, the impregnation layer includes high temperature resistant reinforcing resin such as polyimide resin or phenolic resin or aramid resin, high temperature resistant reinforcing resin is the temperature resistant resin that is greater than 280 ℃. The puncture strength of the polyimide porous membrane layer is 0.68N, and the MD tensile strength of the porous diaphragm is 2 times greater than that of the polyimide base membrane.

The composite film is characterized by also comprising an alumina coating and an adhesive layer which are positioned between the polyimide porous film layer and the polyolefin porous film layer, wherein the polyolefin porous film layer and the polyimide porous film layer are compounded through the alumina coating and the adhesive layer, the alumina coating is close to the polyimide porous film layer, and the adhesive layer is close to the polyolefin porous film layer; the aluminum oxide coating comprises the following components in parts by weight: 200 parts of water, 100 parts of alumina powder, 0.3-1.2 parts of emulsifier, 0.2-0.4 part of thickener and 5-10 parts of binder. In this embodiment, the binder is LA133 or polyacrylate; the emulsifier is AEO-9 or OP emulsifier.

This example provides a method of making the above-described battery separator,

step 1, spraying a resin solution on the surface of a polyimide base film;

step 2, soaking the polyimide base membrane in a resin solution, wherein the mass fraction of resin in the resin solution is 10%, and part of pore channels are filled without blocking the pore channels, so that the air permeability of the cured polyimide porous membrane layer is 15-120s/100 mL;

step 3, uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 20 ℃, and curing at 160 ℃ to obtain a polyimide porous membrane layer;

step 4, coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

Example 3

The embodiment provides a battery diaphragm, including porous rete of polyolefin and the porous rete of polyimide, the porous rete of polyimide includes polyimide base film and cladding in the outside impregnation layer of polyimide base film, the impregnation layer includes high temperature resistant reinforcing resin such as polyimide resin or phenolic resin or aramid resin, high temperature resistant reinforcing resin is the temperature resistant resin that is greater than 280 ℃. The puncture strength of the polyimide porous membrane layer is 2.4N, and the MD tensile strength of the porous diaphragm is 2 times greater than that of the polyimide base membrane.

This example provides a method of making the above-described battery separator,

step 1, spraying a polyimide resin solution on the surface of a polyimide base film;

step 2, soaking the polyimide base membrane in a polyimide resin solution, wherein the mass fraction of resin in the polyimide resin solution is 25%, filling partial pore channels without blocking the pore channels, and enabling the air permeability of the cured polyimide porous membrane layer to be 15-120s/100 mL;

step 3, uniformly coating the resin solution on the surface of the impregnated polyimide base membrane, drying at 50 ℃, and curing at 260 ℃ to obtain a polyimide porous membrane layer;

step 4, coating an aluminum oxide coating on the surface of one side of the polyimide porous membrane layer;

Examples of the experiments

Table 1: comparison of polyimide porous film Performance before and after impregnation

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

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