CN211605260U

CN211605260U - Lithium ion battery composite diaphragm

Info

Publication number: CN211605260U
Application number: CN201922103712.7U
Authority: CN
Inventors: 刘向春; 刘向建; 朱锋
Original assignee: Shenzhen Dingtaixiang New Energy Technology Co ltd
Current assignee: Shenzhen Dingtaixiang New Energy Technology Co ltd
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2020-09-29
Anticipated expiration: 2029-11-29

Abstract

The application discloses a lithium ion battery composite diaphragm, which comprises a porous base film, wherein conductive coatings are arranged on the surfaces of one side or two sides of the porous base film; the surface of conductive coating is equipped with the insulating layer, the surface of insulating layer is equipped with antistatic layer. The conductive coating in the embodiment fixes the anions in the lithium salt to the polymer chains, and the polymer chains are difficult to migrate due to large molecular weight and volume, so that the movement of the anions is limited, only lithium ions migrate, and the migration number of the lithium ions can be close to 1 theoretically. The porous base membrane is compounded on the surface of the porous base membrane by a coating method, and the coating method has excellent effect, is economical and convenient. The diaphragm is subjected to heat insulation treatment through the heat insulation layer, so that the lithium ion battery is safer in use. The electronic conductivity of the diaphragm is improved through the antistatic layer, the problem of coating static electricity is eliminated, and the electrolyte absorption capacity of the coating can be further improved.

Description

Lithium ion battery composite diaphragm

Technical Field

The application relates to the field of lithium ion battery diaphragm materials, in particular to a lithium ion battery composite diaphragm, for example, a composite diaphragm containing a single-ion conductive polymer coating.

Background

Lithium ion batteries are widely used because of their many advantages, such as high energy density, no memory effect, long cycle life, etc. Generally, a lithium ion battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, a separator, and a battery case. Among them, the separator is referred to as the "third pole" of the battery because of its critical role in lithium ion batteries.

The low lithium ion transport number due to lithium salts such as LiPF6, which are common in electrolytes, will result in strong lithium salt concentration gradients at high charge/discharge rates, and result in dendritic growth and ultimately limited power delivery. Therefore, it is necessary to provide a separator structure for increasing the transference number of lithium ions in a lithium ion battery.

SUMMERY OF THE UTILITY MODEL

The present application aims to provide a composite separator for a lithium ion battery, in particular a composite separator comprising a single ion conducting polymer coating, to solve at least one of the problems set forth in the above background.

In order to achieve the purpose, the following technical scheme is adopted in the application:

the specific embodiment provides a lithium ion battery composite diaphragm, which comprises a porous base film, wherein one side or two side surfaces of the porous base film are provided with conductive coatings; the surface of conductive coating is equipped with the insulating layer, the surface of insulating layer is equipped with antistatic layer.

In some embodiments, the porous base film is made of at least one material selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyphenylene oxide, and polyphenylene sulfide.

In some embodiments, the porous base membrane has a thickness of 3 to 25 μm and a pore size of 15 to 80 nm.

In some embodiments, the conductive coating comprises a single ion conductive polymer and a binder, the conductive coating has a pore size of 1 to 15nm, and the weight ratio of the single ion conductive polymer to the binder is 1 to 9: 1.

in some embodiments, the single ion conducting polymer is a lithium bis-sulfonimide-based single ion conducting polymer.

In some embodiments, the binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymethyl methacrylate copolymer, polyvinyl alcohol, polyvinyl acetate, styrene-butadiene latex, ethylene-vinyl acetate copolymer, sodium carboxymethyl cellulose, and polyvinyl pyrrolidone.

In some embodiments, the thermal barrier layer is a ceramic coating.

In some embodiments, the antistatic layer comprises a carbon material having a resistivity of 0.005 to 0.02 Ω -m.

In some embodiments, the carbon material is at least one of carbon fiber, carbon nanotube, activated carbon, fullerene, and expanded graphite.

In some embodiments, the carbon material in the antistatic layer is present in an amount of 2 to 10% by weight.

The conductive coating in the embodiment fixes the anions in the lithium salt to the polymer chains, and the polymer chains are difficult to migrate due to large molecular weight and volume, so that the movement of the anions is limited, only lithium ions migrate, and the migration number of the lithium ions can be close to 1 theoretically. The porous base membrane is compounded on the surface of the porous base membrane by a coating method, and the coating method has excellent effect, is economical and convenient. The diaphragm is subjected to heat insulation treatment through the heat insulation layer, so that the lithium ion battery is safer in use. The electronic conductivity of the diaphragm is improved through the antistatic layer, the problem of coating static electricity is eliminated, and the electrolyte absorption capacity of the coating can be further improved.

Drawings

Fig. 1 is a schematic structural view of a lithium ion battery rich composite separator according to the present embodiment.

FIG. 2 shows the chemical formula of the lithium bis (sulfonimide) based single ion conducting polymer.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Furthermore, the drawings are merely schematic illustrations of embodiments of the disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repetitive description will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities.

In the present embodiment, a lithium ion battery composite separator is provided, as shown in fig. 1, the composite separator includes a porous base film 1, and a conductive coating 2 is provided on one or both surfaces of the porous base film 1; the surface of the conductive coating 2 is provided with a heat insulation layer 3, and the surface of the heat insulation layer 3 is provided with an antistatic layer 4.

Optionally, in some embodiments, the porous base film is made of at least one material selected from polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyphenylene oxide, and polyphenylene sulfide, but is not limited thereto. The porous base membrane of the material has the advantages of good moisture resistance, heat resistance, high tensile strength, strong barrier property and the like, is not easily affected by humidity, and improves the performance of the battery.

Alternatively, in some embodiments, the porous base membrane may have a thickness of 3 to 25 μm and a pore size of 15 to 80 nm.

Optionally, in some embodiments, the conductive coating includes a single-ion conductive polymer and a binder, the pore size of the conductive coating is 1-15nm, and the weight ratio of the single-ion conductive polymer to the binder is 1-9: 1. the percentage content of the single-ion conductive polymer is set according to the amount of lithium ions to be transferred so as to meet the requirements of the battery.

Optionally, in some embodiments, as shown in fig. 2, the single-ion conducting polymer is a lithium bis (sulfonimide) based single-ion conducting polymer, and has good electrical conductivity, which facilitates migration of lithium ions.

In addition, optionally, the single ion conducting polymer may further include a lithium bis-sulfonimide-based single ion conducting polymer and a polyvinylidene fluoride copolymer.

Optionally, in some embodiments, the binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymethyl methacrylate copolymer, polyvinyl alcohol, polyvinyl acetate, styrene-butadiene latex, ethylene-vinyl acetate copolymer, sodium carboxymethyl cellulose, and polyvinyl pyrrolidone. The lithium-rich material is used for bonding the lithium-rich material in the conductive coating layer, so that the lithium-rich material is firmly arranged on the porous base membrane.

Optionally, in some embodiments, the thermal insulation layer is a ceramic coating, the ceramic coating may include a ceramic particulate material, and the thickness of the ceramic particulate material layer may be 5-10 μm, but is not limited thereto. The ceramic particle material layer has higher strength, good fracture toughness and wear resistance, can better protect the diaphragm and prolong the service life of the diaphragm.

Optionally, in some embodiments, the antistatic layer comprises a carbon material having a resistivity of 0.005 to 0.02 Ω · m.

Optionally, in some embodiments, the carbon material is at least one of carbon fiber, carbon nanotube, activated carbon, fullerene, and expanded graphite.

Optionally, in some specific embodiments, the mass percentage of the carbon material in the antistatic layer is 2 to 10%, which satisfies the requirement of antistatic property.

It is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like in the foregoing description are used for indicating or indicating the orientation or positional relationship illustrated in the drawings, merely for the convenience of describing the disclosed embodiments and for simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and therefore should not be considered limiting of the disclosed embodiments.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

In the embodiments of the present disclosure, unless otherwise specifically stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

In the embodiments of the present disclosure, unless otherwise expressly specified or limited, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or may comprise the first and second features being in contact, not directly, but via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

1. A lithium ion battery composite diaphragm is characterized in that: the composite diaphragm comprises a porous base membrane, wherein one side or two side surfaces of the porous base membrane are provided with conductive coatings; the surface of conductive coating is equipped with the insulating layer, the surface of insulating layer is equipped with antistatic layer.

2. The composite membrane of claim 1, wherein: the porous base membrane is made of at least one of polyethylene, polypropylene, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyphenylene oxide and polyphenylene sulfide.

3. The composite membrane of claim 1, wherein: the thickness of the porous basement membrane is 3-25 μm, and the pore diameter is 15-80 nm.

4. The composite membrane of claim 1, wherein: the conductive coating comprises a single-ion conductive polymer and a binder, and the pore diameter of the conductive coating is 1-15 nm.

5. The composite membrane of claim 4, wherein: the single-ion conducting polymer is a poly-bis-sulfimide lithium-based single-ion conducting polymer.

6. The composite membrane of claim 4, wherein: the binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymethyl methacrylate copolymer, polyvinyl alcohol, polyvinyl acetate, styrene-butadiene latex, ethylene-vinyl acetate copolymer, sodium carboxymethylcellulose and polyvinylpyrrolidone.

7. The composite membrane of claim 1, wherein: the heat insulation layer is a ceramic coating.

8. The composite membrane of claim 1, wherein: the antistatic layer comprises a carbon material having a resistivity of 0.005-0.02 Ω · m.

9. The composite membrane of claim 8, wherein: the carbon material is at least one of carbon fiber, carbon nano tube, activated carbon, fullerene and expanded graphite.