WO2021227379A1

WO2021227379A1 - Fiber-coated separator and preparation method therefor, fiber coating, and lithium battery

Info

Publication number: WO2021227379A1
Application number: PCT/CN2020/123943
Authority: WO
Inventors: 尚文滨; 李正林; 张立斌; 陈朝晖; 刘科
Original assignee: 江苏厚生新能源科技有限公司
Priority date: 2020-05-15
Filing date: 2020-10-27
Publication date: 2021-11-18
Also published as: CN111554859A

Abstract

The present invention relates to the technical field of separators, in particular, to a fiber-coated separator and a preparation method therefor, a fiber coating, and a lithium battery. The fiber-coated separator comprises a base film and a fiber coating applied on the surface of the base film; the fiber coating comprises a fiber, a binder, a dispersant, and an initiator. According to the fiber-coated separator in the present invention, the use of an organic high-temperature-resistant fiber instead of ceramic powder not only solves the problem of poor high temperature stability of the base film, but also makes the coated separator lighter in weight, and a battery made of the coated separator has good capacity density; moreover, the fiber has a certain aspect ratio, so that the fiber coating has relatively high porosity, making the prepared coated separator have relatively good liquid retention capability; in addition, the coating is made of an organic fiber and the fiber coating has a certain compression elasticity, and thus, during manufacturing and use of a battery, the problem that the safety characteristics of the battery is affected by microscopic damage to the base film caused by a pole piece compressing the separator is avoided.

Description

Fiber-coated diaphragm, preparation method thereof, fiber coating, and lithium battery

Technical field

The invention belongs to the technical field of diaphragms, and specifically relates to a fiber-coated diaphragm, a preparation method thereof, a fiber coating, and a lithium battery.

Background technique

Because lithium batteries have good secondary cycle characteristics and high capacity density, they are widely used in mobile communications, energy storage, electric vehicles and other fields.

As one of the four major constituent materials of lithium batteries, the lithium battery separator plays a key role in the performance of the battery. The separator plays a role in isolating the positive and negative electrodes in the lithium battery while providing a channel for lithium ions to pass through.

At present, the lithium battery separator in the industry is mainly PE or PP. Due to the chemical properties of the material itself, the PE or PP separator has poor high temperature stability performance.

At present, the industry generally uses ceramic coatings on the surface of lithium battery diaphragms to solve the high temperature dimensional stability of lithium battery diaphragms. However, ceramic coated diaphragms have a higher areal density. After the battery is made, the overall quality is higher, which is not conducive to Increase in battery energy density.

Summary of the invention

The purpose of the present invention is to provide a fiber-coated diaphragm, a preparation method thereof, a fiber coating, and a lithium battery.

In order to solve the above technical problems, the present invention provides a fiber-coated separator, including: a base film and a fiber coating coated on the surface of the base film; the fiber coating includes: fibers, binders, dispersants, and initiators. Agent.

Further, the fiber includes one or more of polyamide, polyimide, para-aramid, meta-aramid, PMMA, acrylic, and polyester.

Further, the fiber has a structure of a hydrocarbon chain.

Further, the fiber diameter is 0.01um-30um; the fiber length is 0.1um-150um; and the aspect ratio of the fiber is 0.2-50.

Further, the binder includes: one or more of styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride, polyvinyl acetate, and ethylene-vinyl acetate copolymer Kind of combination.

Further, the dispersant includes: one or more combinations of sodium polyacrylate, ammonium polyacrylate, polyethylene glycol, sodium carboxymethyl cellulose, ammonium carboxymethyl cellulose, and polyethylene oxide.

Further, the structural formula of the initiator is:

In another aspect, the present invention also provides a method for preparing a fiber-coated diaphragm, including: preparing a fiber slurry; coating the fiber slurry on the surface of the base film; and catalyzing the base film coated with the fiber slurry effect.

In the third aspect, the present invention also provides a fiber coating comprising: 5-50 parts by weight fiber, 0.01-20 parts by weight binder, 0.01-10 parts by weight dispersant, and 0.03-5 parts by weight initiator.

In a fourth aspect, the present invention also provides a lithium battery, including: a separator; the separator adopts the fiber-coated separator as described above.

The beneficial effect of the present invention is that the fiber-coated diaphragm of the present invention uses organic high-temperature resistant fibers instead of ceramic powder, which not only solves the problem of poor high-temperature stability of the base film, but also makes the coated diaphragm have a lighter weight. The battery produced by the coated separator has a better capacity density; at the same time, because the fiber has a certain aspect ratio, the fiber coating has a higher porosity, so that the produced coated separator has a better liquid retention capacity; further Because the coating uses organic fibers, the fiber coating has a certain degree of compression elasticity. During the production and use of the battery, it avoids the problem that the pole piece compresses the diaphragm and damages the base film at the microscopic level and affects the safety characteristics of the battery. .

Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or understood by implementing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures specified in the specification and claims.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are specifically described below in detail.

Description of the drawings

Fig. 1 is a step diagram of the method for preparing the fiber-coated separator of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be described below clearly and completely. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. . Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Example 1

This embodiment 1 provides a fiber-coated separator, including: a base film and a fiber coating coated on the surface of the base film; the fiber coating includes: fibers, a binder, a dispersant, and an initiator.

Specifically, the base film includes, but is not limited to, one or more combinations of PE film, PP film, and non-woven film, preferably a PE film; the PE film is preferably a polyolefin membrane with a pore size distribution of 30nm-80nm .

As an alternative embodiment of the fiber.

The fiber includes one or more of polyamide, polyimide, para-aramid, meta-aramid, PMMA, acrylic, and polyester.

Specifically, the fiber is an organic high temperature resistant fiber, and the fiber of this embodiment has a structure of a hydrocarbon chain.

Further, the fiber diameter is 0.01um-30um, such as 0.01um, 5um, 10um, 25um or 30um; the fiber length is 0.1um-150um, such as 0.1um, 100um or 150um; and the aspect ratio of the fiber It is 0.2-50, such as 0.2, 20 or 50.

As an alternative embodiment of the adhesive.

The binder includes: one or more combinations of styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride, polyvinyl acetate, and ethylene-vinyl acetate copolymer .

Specifically, the binder has a hydrocarbon chain structure.

As an alternative embodiment of the dispersant.

The dispersant includes: one or more combinations of sodium polyacrylate, ammonium polyacrylate, polyethylene glycol, sodium carboxymethyl cellulose, ammonium carboxymethyl cellulose, and polyethylene oxide.

As an alternative embodiment of the initiator.

The structural formula of the initiator is:

Specifically, in the initiator, R is a hydrocarbon chain structure with C atoms of 5-20; this embodiment introduces an initiator to cross-link and solidify the fiber, binder, and base film, resulting in an integrated The structured fiber-coated separator has high peel strength and heat shrinkage characteristics.

Because the fiber-coated diaphragm of Example 1 uses organic high-temperature resistant fiber instead of ceramic powder, it not only solves the problem of poor high-temperature stability of the base film, but also makes the coated diaphragm have a lighter quality. The battery has a better capacity density; at the same time, because the fiber has a certain length-to-diameter ratio, the fiber coating has a higher porosity, so that the fabricated coated separator has a better liquid retention capacity; further, due to the use of the coating It is an organic fiber, and the fiber coating has a certain compression elasticity. During the production and use of the battery, it avoids the problem that the pole piece compresses the diaphragm and damages the base film microscopically and affects the safety characteristics of the battery.

Example 2

As shown in Figure 1, on the basis of Example 1, this Example 2 provides a method for preparing a fiber-coated diaphragm, including: step S1, preparing a fiber slurry; step S2, coating the fiber slurry on The surface of the base film; and step S3, catalyzing the base film coated with the fiber slurry.

Specifically, the method for preparing the fiber slurry includes: cutting the fibers into fiber particles with a certain aspect ratio; adding the dispersant to the water, mixing uniformly, adding the fiber particles, after uniformly stirring, adding the binder to stir and disperse, adding the initiator After mixing and dispersing, the fiber slurry is prepared.

Specifically, the catalytic effect includes, for example, but not limited to: light, ultraviolet radiation, electron beam radiation, or high-temperature drying.

Example 3

On the basis of Examples 1 and 2, this Example 3 provides a fiber coating comprising: 5-50 parts by weight fiber, 0.01-20 parts by weight binder, 0.01-10 parts by weight dispersant, and 0.03- 5 parts by weight initiator.

Example 4

Step S1: Cut 15kg of fibers into fiber pellets with a certain aspect ratio, add 500g of dispersant into water, stir evenly, add fiber pellets, and after stirring, add 500g of binder and stir to disperse, add 150g of initiator, and stir After dispersion, a fiber slurry is prepared.

In step S2, the fiber slurry obtained in step S1 is coated on the surface of the base film.

In step S3, the fiber-coated diaphragm is obtained after light, ultraviolet radiation, electron beam radiation or high-temperature drying.

Example 5

Step S1: Cut 25kg fiber into fiber pellets with a certain aspect ratio, add 800g dispersant into water, stir evenly, add fiber pellets, after stirring, add 800g binder and stir to disperse, add 250g initiator, stir After dispersion, a fiber slurry is prepared.

Example 6

Step S1: Cut 40kg of fibers into fiber pellets with a certain aspect ratio, add 1kg of dispersant into water, stir evenly, add fiber pellets, after stirring evenly, add 1.2kg of binder to stir and disperse, add 800g of initiator, After stirring and dispersing, a fiber slurry is prepared.

Example 7

On the basis of Embodiment 1, this Embodiment 7 provides a lithium battery, including: a separator; the separator adopts the fiber-coated separator as described in Embodiment 1.

Specifically, for the specific parameters of the fiber-coated diaphragm, please refer to the relevant discussion in Embodiment 1, which will not be repeated here.

In summary, the fiber-coated diaphragm of the present invention uses organic high-temperature resistant fiber instead of ceramic powder, which not only solves the problem of poor high-temperature stability of the base film, but also makes the coated diaphragm have a lighter weight. The battery produced by the rear diaphragm has a better capacity density; at the same time, because the fiber has a certain aspect ratio, the fiber coating has a higher porosity, so that the produced coated diaphragm has a better liquid retention capacity; further, due to The coating uses organic fibers, and the fiber coating has a certain degree of compression elasticity. During the production and use of the battery, it avoids the problem that the pole piece compresses the diaphragm and damages the base film microscopically and affects the safety characteristics of the battery.

Taking the above-mentioned ideal embodiment according to the present invention as enlightenment, through the above-mentioned description content, relevant workers can make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the content of the description, and the technical scope must be determined according to the scope of the claims.

Claims

A fiber-coated diaphragm, which is characterized in that it comprises:

Base film and fiber coating on the surface of the base film;

The fiber coating includes: fiber, binder, dispersant and initiator.
The fiber-coated membrane according to claim 1, wherein:

The fiber includes one or more of polyamide, polyimide, para-aramid, meta-aramid, PMMA, acrylic, and polyester.
The fiber-coated membrane according to claim 2, wherein:

The fiber has a structure of a hydrocarbon chain.
The fiber-coated membrane according to claim 2, wherein:

The fiber diameter is 0.01um-30um;

The fiber length is 0.1um-150um; and

The aspect ratio of the fiber is 0.2-50.
The fiber-coated membrane according to claim 1, wherein:

The binder includes: one or more combinations of styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride, polyvinyl acetate, and ethylene-vinyl acetate copolymer .
The fiber-coated membrane according to claim 1, wherein:

The dispersant includes: one or more combinations of sodium polyacrylate, ammonium polyacrylate, polyethylene glycol, sodium carboxymethyl cellulose, ammonium carboxymethyl cellulose, and polyethylene oxide.
The fiber-coated membrane according to claim 1, wherein:

The structural formula of the initiator is:
A method for preparing a fiber-coated diaphragm, which is characterized in that it comprises:

Prepare fiber slurry;

Coating the fiber slurry on the surface of the base film; and

Catalyze the base film coated with fiber slurry.
A fiber coating, characterized in that it comprises:

5-50 parts by weight fiber, 0.01-20 parts by weight binder, 0.01-10 parts by weight dispersant, and 0.03-5 parts by weight initiator.
A lithium battery, characterized in that it comprises:

Diaphragm

The membrane adopts the fiber-coated membrane according to claim 1.