CN109866492B

CN109866492B - Aluminum-plastic film, preparation method thereof and anti-falling lithium battery

Info

Publication number: CN109866492B
Application number: CN201910011349.8A
Authority: CN
Inventors: 潘珊珊
Original assignee: Huizhou Highpower Technology Co Ltd
Current assignee: Huizhou Highpower Technology Co Ltd
Priority date: 2019-01-07
Filing date: 2019-01-07
Publication date: 2021-09-21
Anticipated expiration: 2039-01-07
Also published as: CN109866492A

Abstract

The invention discloses an aluminum-plastic film for improving the falling-resisting performance of a lithium battery, a preparation method of the aluminum-plastic film and the corresponding lithium battery. The aluminum-plastic film comprises an aluminum-plastic film substrate and a polymer layer, wherein the polymer layer is mainly made of polymethacrylate compounds, and the polymer layer is used for isolating the aluminum-plastic film substrate from a battery cell. The polymethacrylate compound material is positioned on the inner surface of the aluminum-plastic film to form a stable protective layer, has good thermal stability, hardness and rigidity, can play good buffering and protecting roles when the lithium battery is impacted by a heavy object, falls at a low height and the like on the basis of ensuring that the electrical property of the lithium battery is not influenced, and effectively improves the safety performance of the lithium battery.

Description

Aluminum-plastic film, preparation method thereof and anti-falling lithium battery

Technical Field

The invention relates to the field of batteries, in particular to an aluminum-plastic film, a preparation method thereof and an anti-falling lithium battery.

Background

The soft package lithium ion battery consists of an aluminum plastic film, an electric core and electrolyte, has the characteristics of light weight, large capacity, small internal resistance, high energy density, long cycle life, stable discharge platform and the like, and is favored by domestic and foreign users. The soft package lithium battery product is also widely applied to a plurality of fields such as electric vehicles, mobile power supplies, digital electronic products, intelligent wearable products, electric toys and the like.

The aluminum plastic film generally used by the existing soft package lithium battery is roughly divided into three layers from outside to inside, namely an outer barrier layer (generally an outer protective layer formed by nylon BOPA or PET), a barrier layer (mainly an aluminum middle layer of aluminum foil) and an inner layer (a multifunctional high barrier layer). The inner layer is close to the coated battery core and the electrolyte, mainly adopts polypropylene (PP) or cast/unstretched polypropylene (CPP) materials, and the inner layer materials have low strength, are easy to wear and are afraid of hard or sharp foreign matters. Like this, when laminate polymer battery takes place to fall and falls ground or other positions, its edge easily strikes and breaks, leads to the pole piece of inside electric core and diaphragm to take place to turn over a book and arouse short circuit to catch fire scheduling problem. Therefore, it is necessary to provide a drop-resistant lithium battery to solve the above problems.

Disclosure of Invention

The invention aims to provide an aluminum plastic film for improving the falling-resisting performance of a lithium battery, a preparation method thereof and a corresponding lithium battery.

The technical scheme adopted by the invention is as follows:

an aluminum-plastic film comprises an aluminum-plastic film base body, wherein a polymer layer is arranged on one side, close to a battery core, of the aluminum-plastic film base body in use, and the polymer layer is mainly made of polymethacrylate materials.

Preferably, the polymethacrylate material is at least one of polymethyl methacrylate, polyethyl methacrylate, polyhydroxyethyl methacrylate, polypropylene methacrylate and polybutyl methacrylate.

Further preferably, the polymethacrylate material is polymethyl methacrylate.

Preferably, the aluminum-plastic film substrate comprises an outer resistance layer, an aluminum intermediate layer and an inner layer which are adjacent in sequence.

Further preferably, the main material of the outer barrier layer is at least one of polyamide or polyethylene terephthalate.

Further preferably, the main material of the inner layer is polypropylene.

The preparation method of the aluminum-plastic film comprises the following steps:

taking or preparing an aluminum-plastic film matrix;

and mixing an initiator, a monomer and a solvent, and coating the mixture on an aluminum plastic film substrate to form a polymer layer.

Preferably, the coating method further comprises the steps of baking and rolling after coating.

An anti-falling lithium battery comprises the aluminum plastic film.

The invention has the beneficial effects that:

the invention provides an aluminum-plastic film with a polymer layer, which takes the aluminum-plastic film in the prior art as an aluminum-plastic film substrate, and a polymethacrylate material layer is constructed on the inner surface of the aluminum-plastic film, wherein the polymer layer has good thermal stability, hardness and rigidity and can provide stable protection. Particularly, the polymer layer can play a very good role in buffering and protecting on the basis of ensuring that the electrical property of the lithium battery is not influenced. When the lithium cell takes place by the condition such as low-height falling, the polymer layer of plastic-aluminum membrane can comparatively realize the effect that the buffering was prevented falling owing to its better rigidity and hardness that has simultaneously, avoids outside deformation and conducts inside power from this well, and furthest reduces the pole piece of cladding in the inside electric core of plastic-aluminum membrane and the diaphragm because of taking place deformation such as turning over a book and the emergence of the condition such as short circuit that arouses the short circuit and fire explosion because of turning over, effectively improves the security performance of lithium cell.

Drawings

Fig. 1 is a schematic view of an aluminum plastic film according to an embodiment of the present invention.

Detailed Description

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below, so that the objects, the features, and the effects of the present invention can be fully understood. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

Fig. 1 is a schematic view of an aluminum plastic film according to an embodiment of the present invention. As shown in fig. 1, the aluminum-plastic film comprises an adjacent aluminum-plastic film base body and a polymer layer, wherein the aluminum-plastic film base body comprises an outer resistance layer 1, a first adhesive layer 51 for bonding the outer resistance layer 1 and the aluminum intermediate layer 2, a second adhesive layer 52 for bonding the aluminum intermediate layer 2 and the inner layer 3, the inner layer 3 and the polymer layer 4 which are adjacent in sequence; wherein, the outer resistance layer 1 is a PET film with the thickness of 25 μm, the first adhesive layer 51 and the second adhesive layer 52 are polyurethane adhesives, the aluminum middle layer 2 is an aluminum foil with the thickness of 40 μm, the inner layer 3 is a cast polypropylene film with the thickness of 40 μm, and the polymer layer 4 is a polymethyl methacrylate film.

The preparation method of the aluminum-plastic film specifically comprises the following steps:

(1) coating polyurethane adhesive on the surface of the external resistance layer 1 by a dry compounding machine in a coating mode, wherein the coating weight of the adhesive is 4-6g/m²And after coating, sending the mixture into an oven for drying, wherein the temperature of the oven is set to be 90-110 ℃, and the drying time is 15 s. Drying to obtain an intermediate product I.

(2) And compounding the first intermediate product and the aluminum intermediate layer 2 together by using a compounding roller at about 60 ℃ to form a second intermediate product.

(3) Coating polyurethane adhesive on the surface of the aluminum intermediate layer 2 of the second intermediate product in a coating mode on a dry compounding machine, wherein the coating weight of the adhesive is 4-6g/m²And after coating, sending the mixture into an oven for drying, wherein the temperature of the oven is set to be 90-110 ℃, and the drying time is 15 s. And drying to obtain an intermediate product III.

(4) And compounding the third intermediate product and the inner layer 3 together by using a compounding roller at about 60 ℃ to obtain a fourth intermediate product.

(5) And curing the intermediate product IV for about 72 hours in an environment of about 60 ℃ to obtain the aluminum-plastic film matrix.

(6)1 part by mass of benzoyl peroxide, 1 part by volume of methyl methacrylate and 3 parts by volume of ethyl acetate are mixed and stirred at 50 ℃ for 15-30 min.

(7) The obtained mixture liquid is coated on the inner surface (the surface of the inner layer 3) of the aluminum-plastic film substrate and baked for 2 hours at the temperature of 80 ℃.

(8) And (3) enabling the treated aluminum-plastic film substrate to pass through a pressure roller, so that the polymer layer is firmly adhered to the inner surface of the aluminum-plastic film substrate to obtain the aluminum-plastic film.

A soft package lithium ion battery comprises a battery cell, electrolyte and the aluminum plastic film; the battery cell comprises a positive plate, a negative plate and a diaphragm, and the specific preparation process comprises the following steps:

uniformly mixing a positive active material, namely lithium cobalt oxide, a binder, namely polyvinylidene fluoride (PVDF), and a conductive agent, namely carbon black, with a solvent, namely N-methyl pyrrolidone, according to a certain mass ratio, stirring at a high speed to obtain dispersed positive slurry, uniformly coating the positive slurry on a positive current collector, namely an aluminum foil, and drying and cold-pressing to obtain a positive plate;

uniformly mixing a negative active material graphite, a binder Styrene Butadiene Rubber (SBR), sodium carboxymethylcellulose (CMC) and a conductive agent carbon black with solvent deionized water according to a certain mass ratio, stirring at a high speed to obtain dispersed negative slurry, uniformly coating the negative slurry on a negative current collector copper foil, drying and cold-pressing to obtain a negative plate;

mixing LiPF₆Preparing a LiPF6 nonaqueous electrolyte solution with Ethylene Carbonate (EC) and diethyl carbonate (DEC);

the positive plate, the negative plate and the isolating film PE film are wound into a battery cell, the aluminum-plastic film is subjected to pit punching according to the size of the battery cell, then the battery cell is placed in an inner pit of the aluminum-plastic film to complete assembly (a polymer layer is arranged on one side, close to the battery cell, of the aluminum-plastic film), finally the LiPF6 non-aqueous electrolyte is injected, the sealed space is formed by heating through a high-temperature seal head and fusing an inner layer at a top sealing position, packaging is completed, and then procedures such as formation, capacity and the like are performed, so that the soft package lithium ion battery is obtained.

Example 2

An aluminum-plastic film is different from the aluminum-plastic film in example 1 in that the material of the polymer layer is a poly (ethyl methacrylate) film.

Example 3

An aluminum-plastic film is different from the aluminum-plastic film in example 1 in that the material of the polymer layer is a poly (propyl methacrylate) film.

Example 4

Drop-resistant performance comparison experiment:

the aluminum-plastic films of examples 1 to 3 and a comparative example (the aluminum-plastic film without a polymer layer in the prior art) are respectively adopted to wrap the soft package battery cell 404798 to form 8 soft package batteries for experiments, the positive electrode, the negative electrode and the diaphragm are kept consistent, and anti-falling tests are respectively carried out, wherein the specific test method comprises the following steps:

the cell was placed in a flat surface with a 15.8mm diameter steel post centered in the cell with the longitudinal axis of the post parallel to the flat surface, allowing a weight of 9.1kg to fall freely from a height of 610mm onto the post above the center of the cell.

The results of the drop test are shown in the following table:

TABLE 1 anti-crash test results

	Example 1	Example 2	Example 3	Comparative example 1
					Test pass ratio	100％	100％	100％	12.5％

It can be seen from the above results that the plastic-aluminum membrane provided by the above embodiment can effectively slow down the impact in the dropping process on the battery cell, and the occurrence of phenomena such as short circuit, fire and the like caused by the turnover of the pole piece and the diaphragm inside the battery cell can be avoided to the greatest extent.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The utility model provides an prevent falling lithium cell, its characterized in that, includes the plastic-aluminum membrane, the plastic-aluminum membrane includes plastic-aluminum membrane base member and polymer layer, the polymer layer coat in the internal surface of plastic-aluminum membrane base member, the material of polymer layer includes polymethacrylate class material, the plastic-aluminum membrane base member is including adjacent outer layer, aluminium intermediate level and the inlayer of hindering in proper order, the inlayer with the laminating of polymer layer.

2. The drop-resistant lithium battery of claim 1, wherein the polymethacrylate material comprises at least one of polymethylmethacrylate, polyethylmethacrylate, polyhydroxyethylmethacrylate, polypropylmethacrylate, polybutylmethacrylate.

3. The drop-resistant lithium battery of claim 2, wherein the polymethacrylate material is polymethylmethacrylate.

4. The drop-resistant lithium battery of claim 1 wherein the material of the outer barrier layer comprises at least one of polyamide and polyethylene terephthalate.

5. The drop-resistant lithium battery of claim 1, wherein the material of the inner layer comprises polypropylene.