CN216928854U

CN216928854U - High-temperature-resistant lithium battery diaphragm

Info

Publication number: CN216928854U
Application number: CN202220135166.4U
Authority: CN
Inventors: 陈琪; 马千里; 唐凯; 高殿飞; 潘玉琳; 尚晴
Original assignee: YANTAI TAYHO ADVANCED MATERIALS CO Ltd
Current assignee: Taihe New Material Group Co ltd
Priority date: 2022-01-18
Filing date: 2022-01-18
Publication date: 2022-07-08
Anticipated expiration: 2032-01-18

Abstract

The utility model discloses a high-temperature-resistant lithium battery diaphragm which comprises a polyolefin microporous membrane substrate layer, wherein an aramid fiber coating layer is arranged on one side or both sides of the polyolefin microporous membrane substrate layer, and the aramid fiber coating layer comprises a wet aramid fiber porous membrane layer arranged on the surface of the polyolefin microporous membrane substrate layer and an aramid fiber nano-fiber layer arranged on the surface of the wet aramid fiber porous membrane layer. The utility model can greatly improve the heat resistance of the diaphragm, thereby improving the safety of the lithium battery in the using process.

Description

High-temperature-resistant lithium battery diaphragm

Technical Field

The utility model belongs to the field of lithium battery materials, and particularly relates to a high-temperature-resistant lithium battery diaphragm.

Background

In recent years, the emerging electric automobile industry and the lithium battery industry are rapidly developed, and a lithium battery diaphragm is used as one of key components of a lithium battery and is also a high-value-added material with the highest technical barrier, so that the market demand is rapidly increased. However, China is at the low end of the industrial chain as a whole, and the diaphragms for high-end power and energy storage batteries have great differences with foreign diaphragm products in the aspects of lithium battery safety, cruising ability, service life and the like, so that the diaphragms are bottlenecks restricting the development of electric vehicles in China.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a high-temperature-resistant lithium battery diaphragm, which overcomes the defects in the prior art, and can greatly improve the heat resistance of the diaphragm, thereby improving the safety of a lithium battery in the using process.

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

the utility model provides a high temperature resistant lithium battery diaphragm, includes polyolefin microporous membrane substrate layer, one side of polyolefin microporous membrane substrate layer is provided with aramid fiber coating layer or both sides all are provided with aramid fiber coating layer, aramid fiber coating layer is including setting up the porous rete of wet process aramid fiber on polyolefin microporous membrane substrate layer surface and setting up the aramid fiber nanofiber layer on wet process aramid fiber porous membrane layer surface.

Further, the polyolefin microporous membrane substrate layer adopts one of polyethylene, polypropylene and polypropylene/polyethylene/polypropylene.

Further, the wet aramid porous membrane layer is prepared by a phase conversion method of a casting solution of aramid polymer on a polyolefin microporous membrane substrate layer.

Furthermore, the thickness of the wet aramid fiber porous membrane is 0.5-10 μm, and the pore diameter is 0.5-3 μm.

Further, the aramid nano-fiber layer is prepared by coating an aramid nano-fiber aqueous solution on the aramid porous film layer.

Furthermore, the thickness of the aramid nano fiber layer is 0.5-5 μm, and the pore diameter is 50-500 nm.

Furthermore, the diameter of the aramid nano-fiber in the aramid nano-fiber layer is 50-100 nm.

Furthermore, the aramid fiber in the aramid fiber coating layer is meta-aramid fiber or para-aramid fiber.

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

according to the utility model, the aramid fiber is used as the coating layer, so that the bonding force between the coating layer and the polyolefin microporous membrane substrate layer can be improved, the wettability of the diaphragm and the electrolyte is greatly increased, the energy density is increased, the endurance mileage of an automobile is improved, the heat resistance is improved, and the safety performance of the battery is improved; the self-discharge phenomenon of the battery is reduced, the cycle performance of the battery is improved, and the method can be applied to the preparation of the lithium battery diaphragm.

The aramid fiber coating layer is used as an organic coating layer, so that the binding power between the coating layer and the base film can be effectively improved, but when the film is formed by a phase-change method, a pore-forming agent is usually added into a film casting solution to adjust the pore size, and the pore-forming agent is introduced to influence the battery performance. The pore diameter of the wet aramid fiber porous film layer is 0.5-3 mu m, the pore diameter is larger, after the aramid fiber nano fiber layer is coated on the wet aramid fiber porous film layer, the pore diameter of the diaphragm can be reduced, self-discharge is reduced, and other pore-forming agents are not introduced, so that other performances of the diaphragm cannot be reduced.

Drawings

FIG. 1 is a schematic structural diagram of a lithium battery diaphragm with a side aramid fiber coating according to the utility model;

fig. 2 is a schematic structural diagram of a lithium battery diaphragm with aramid fiber coatings on two sides.

Wherein, 1 is polyolefin base film base member layer, 2 is the porous rete of wet process aramid fiber, 3 is aramid fiber nanofiber layer, 4 is the macropore that forms in the aramid fiber rete of wet process, and 5 is the aperture that aramid fiber nanofiber overlap formed.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to the attached figure 1, the high-temperature-resistant lithium battery diaphragm comprises a polyolefin microporous membrane substrate layer 1 and aramid fiber coating layers positioned on one side or two sides of the polyolefin microporous membrane substrate layer 1, each aramid fiber coating layer comprises a wet aramid fiber porous membrane layer 2 and an aramid fiber nanofiber layer 3, the polyolefin microporous membrane substrate layer 1 is a polyolefin diaphragm with optional thickness and comprises one of Polyethylene (PE), polypropylene (PP) and polypropylene/polyethylene/polypropylene (PP/PE/PP), the wet aramid fiber porous membrane layer 2 is prepared by a casting film liquid of aramid fiber polymer through a phase conversion method, the thickness of the wet aramid fiber porous membrane layer 2 is 0.5-10 mu m, the pore diameter of a macropore 4 formed in the wet aramid fiber membrane layer is 0.5-3 mu m, and the aramid fiber nanofiber layer 3 is prepared by coating an aramid fiber nanofiber aqueous solution on the aramid fiber porous membrane layer 2, the thickness of the aramid nano fiber layer 3 is 0.5-5 mu m, the aperture of a small hole 5 formed by overlapping the aramid nano fibers is 50-500nm, the diameter of the aramid nano fibers is 50-100nm, and the aramid is one of meta-aramid or para-aramid.

Example 1

The aramid fiber coated lithium battery diaphragm comprises a PE (polyethylene) base film (the thickness is 9 mu m), a wet aramid fiber porous film layer 2 and an aramid fiber nano-fiber layer 3 are sequentially arranged on one side of the PE base film, the thickness of the wet aramid fiber porous film layer 2 is 0.5 mu m, the thickness of the aramid fiber nano-fiber layer 3 is 5 mu m, and macropores 4 formed in the wet aramid fiber film layer and micropores 5 formed by overlapping aramid fiber nano-fibers form through holes, so that lithium ions can pass through the through holes.

Example 2

The aramid fiber coated lithium battery diaphragm comprises a PP (polypropylene) base film (the thickness is 9 mu m), a wet aramid fiber porous film layer 2 and an aramid fiber nano-fiber layer 3 are sequentially arranged on one side of the PP base film, the thickness of the wet aramid fiber porous film layer 2 is 10 mu m, the thickness of the aramid fiber nano-fiber layer 3 is 0.5 mu m, and macropores 4 formed in the wet aramid fiber film layer and micropores 5 formed by overlapping aramid fiber nano-fibers form through holes, so that lithium ions can pass through the through holes.

Example 3

The aramid fiber coated lithium battery diaphragm comprises a PP/PE/PP base film (the thickness is 9 mu m), a wet aramid fiber porous film layer 2 and an aramid fiber nano-fiber layer 3 are sequentially arranged on one side of the PP/PE/PP base film, the thickness of the wet aramid fiber porous film layer 2 is 2.0 mu m, the thickness of the aramid fiber nano-fiber layer 3 is 3.0 mu m, and macropores 4 formed in the wet aramid fiber film layer and micropores 5 formed by overlapping aramid fiber nano-fibers form through holes, so that lithium ions can pass through the through holes.

Example 4

The aramid fiber coated lithium battery diaphragm comprises a PE (polyethylene) base film (the thickness is 9 mu m), a wet aramid fiber porous film layer 2 and an aramid fiber nano-fiber layer 3 are sequentially arranged on two sides of the PE base film, the thickness of the wet aramid fiber porous film layer 2 is 0.5 mu m, the thickness of the aramid fiber nano-fiber layer 3 is 5 mu m, and a through hole is formed by a large hole 4 formed in the wet aramid fiber film layer and a small hole 5 formed by overlapping aramid fiber nano-fibers and can allow lithium ions to pass through.

Comparative example 1

A basic PE film of the aramid fiber coated lithium battery diaphragm is used as the lithium battery diaphragm, and the thickness of the basic PE film is 9 micrometers.

Table 1 comparison of thermal performance test results of examples 1-3 aramid lithium battery separators and comparative example 1 film

Note: "-" indicates that the film had shrunk at this temperature and was not tested.

As can be seen from table 1, the thermal shrinkage of the coated separator with the wet-process aramid porous film layer and the nanofiber layer was greatly improved compared to the polyolefin-based film. The PE basal membrane becomes transparent and shrinks at the high temperature of 150 ℃, the thermal shrinkage of the PE diaphragm with the coating layer is about 1 percent at the high temperature of 150 ℃, and the thermal shrinkage of the PP, PP/PE/PP diaphragms with the coating layers is 0 at the high temperature, which shows that the heat resistance is greatly improved, and the battery safety performance is favorably improved.

Claims

1. The utility model provides a high temperature resistant lithium cell diaphragm, its characterized in that, includes polyolefin microporous membrane substrate layer (1), one side of polyolefin microporous membrane substrate layer (1) is provided with aramid fiber coating layer or both sides all are provided with aramid fiber coating layer, aramid fiber coating layer is including setting up wet process aramid fiber porous membrane layer (2) and aramid fiber nanofiber layer (3) on wet process aramid fiber porous membrane layer (2) surface on polyolefin microporous membrane substrate layer (1) surface.

2. The high temperature resistant lithium battery separator as claimed in claim 1, wherein the polyolefin microporous membrane substrate layer (1) is made of one of polyethylene, polypropylene and polypropylene/polyethylene/polypropylene.

3. The high-temperature-resistant lithium battery separator as claimed in claim 1, wherein the wet aramid porous membrane layer (2) is prepared by a phase conversion method of a casting solution of aramid polymer on the polyolefin microporous membrane substrate layer (1).

4. The high-temperature-resistant lithium battery separator as claimed in claim 1, wherein the wet aramid porous membrane layer (2) has a thickness of 0.5-10 μm and a pore size of 0.5-3 μm.

5. The high-temperature-resistant lithium battery diaphragm as claimed in claim 1, wherein the aramid nanofiber layer (3) is prepared by coating an aramid nanofiber aqueous solution on the aramid porous film layer (2).

6. The high-temperature-resistant lithium battery separator as claimed in claim 1, wherein the aramid nanofiber layer (3) has a thickness of 0.5-5 μm and a pore size of 50-500 nm.

7. The high-temperature-resistant lithium battery separator as claimed in claim 1, wherein the diameter of the aramid nanofiber in the aramid nanofiber layer (3) is 50-100 nm.

8. The high-temperature-resistant lithium battery separator as claimed in claim 1, wherein the aramid fiber in the aramid fiber coating layer is meta-aramid fiber or para-aramid fiber.