CN212967940U

CN212967940U - Composite diaphragm for lithium ion battery

Info

Publication number: CN212967940U
Application number: CN202021104777.XU
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: 2020-06-16
Filing date: 2020-06-16
Publication date: 2021-04-13
Anticipated expiration: 2030-06-16

Abstract

The composite diaphragm for the lithium ion battery comprises an intermediate layer, wherein the intermediate layer is of a porous structure, a first coating is arranged on the upper surface of the intermediate layer, a second coating is arranged on the lower surface of the intermediate layer, and the first coating and the second coating both contain metal-organic framework nano particles. The metal-organic frame material coating has high porosity and large specific surface area, and can improve the electrolyte wettability of the diaphragm; the metal-organic frame material coating can effectively improve the heat resistance of the diaphragm and improve the safety performance of the battery in a high-temperature environment; the uniform pore channel structure of the metal-organic framework material coating enables lithium ions to be uniformly deposited/stripped in the charging and discharging processes, and fundamentally inhibits the growth of lithium dendrites; meanwhile, the metal-organic framework material coating also has good flexibility and mechanical properties.

Description

Composite diaphragm for lithium ion battery

Technical Field

The application relates to the field of lithium ion battery diaphragm materials, in particular to a composite diaphragm for a lithium ion battery, for example, the composite diaphragm for the lithium ion battery containing a metal-organic framework material 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. However, at present, polyolefin separators and coated separators commonly used in the market generally have the defects of low porosity, poor electrolyte wettability, easy generation of severe size shrinkage at high temperature and the like, so that the requirements of high-performance power lithium batteries are difficult to meet.

Disclosure of Invention

It is an object of the present application to provide a composite separator comprising a coating of a metal-organic framework material to solve at least one of the problems set forth in the above-mentioned technical background.

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

the specific embodiment provides a composite diaphragm for a lithium ion battery, which comprises an intermediate layer, wherein the intermediate layer is of a porous structure, a first coating is arranged on the upper surface of the intermediate layer, a second coating is arranged on the lower surface of the intermediate layer, and the first coating and the second coating both contain metal-organic framework nano particles.

In some embodiments, the metal-organic framework nanoparticles are at least one of UIO-66, MIL-101, and ZIF-8.

In some embodiments, the intermediate layer is a microporous membrane made from at least one of polyethylene, polypropylene, polyvinylidene fluoride copolymer, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyphenylene oxide, and polyphenylene sulfide.

In some embodiments, the intermediate layer has an average pore size of 15 to 50nm and a thickness of 5 to 32 μm.

In some embodiments, the first coating layer and the second coating layer each comprise metal-organic framework nanoparticles and a binder, and the mass ratio of the metal-organic framework nanoparticles to the binder is 0.3-9.5: 1.

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 first coating layer and the second coating layer have a thickness of 0.5 to 5 μm.

In some embodiments, the intermediate layer includes an active material layer therein.

In some specific embodiments, a zinc oxide nanowire layer is further disposed between the intermediate layer and the first coating layer or the second coating layer.

In some embodiments, the active material layer includes a lithium transition metal oxide-based active material.

The metal-organic framework material in the embodiment has porosity, a large specific surface area, structural and functional diversity and unsaturated metal sites, has regular nanometer-sized micropores, provides an even and rapid ion channel for lithium ions, has excellent mechanical properties and heat resistance due to excellent framework strength, and brings more excellent effects for a novel lithium battery diaphragm.

The metal-organic frame material coating has high porosity and large specific surface area, and can improve the electrolyte wettability of the diaphragm; the metal-organic frame material coating can effectively improve the heat resistance of the diaphragm and improve the safety performance of the battery in a high-temperature environment; the uniform pore channel structure of the metal-organic framework material coating enables lithium ions to be uniformly deposited/stripped in the charging and discharging processes, and fundamentally inhibits the growth of lithium dendrites; meanwhile, the metal-organic framework material coating also has good flexibility and mechanical properties.

Drawings

Fig. 1 is a schematic structural view of a composite separator for a lithium ion battery.

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.

The specific embodiment provides a composite diaphragm for a lithium ion battery, as shown in fig. 1, the diaphragm includes an intermediate layer 1, the intermediate layer 1 is of a porous structure, a first coating layer 2 is disposed on an upper surface of the intermediate layer, a second coating layer 3 is disposed on a lower surface of the intermediate layer 1, and the first coating layer 2 and the second coating layer 3 both contain metal-organic framework nanoparticles.

The metal-organic frame material coating in the embodiment has high porosity and large specific surface area, and can improve the electrolyte wettability of the diaphragm; the metal-organic frame material coating can effectively improve the heat resistance of the diaphragm and improve the safety performance of the battery in a high-temperature environment; the uniform pore channel structure of the metal-organic framework material coating enables lithium ions to be uniformly deposited/stripped in the charging and discharging processes, and fundamentally inhibits the growth of lithium dendrites; meanwhile, the metal-organic framework material coating also has good flexibility and mechanical properties.

Optionally, in some embodiments, the metal-organic framework nanoparticle is at least one of UIO-66, MIL-101, and ZIF-8.

Optionally, in some embodiments, the intermediate layer is a microporous membrane made of at least one of polyethylene, polypropylene, polyvinylidene fluoride copolymer, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyimide, polyetherimide, polysulfone, polyethersulfone, polyamide, polyphenylene oxide, and polyphenylene sulfide, but is not limited thereto. The composite material has the advantages of good moisture resistance, heat resistance, high tensile strength, strong barrier property and the like, is not easily influenced by humidity, and improves the performance of the battery.

Optionally, in some embodiments, the intermediate layer has an average pore size of 15 to 50nm and a thickness of 5 to 32 μm.

In some embodiments, the first coating layer and the second coating layer each comprise metal-organic framework nanoparticles and a binder, and the mass ratio of the metal-organic framework nanoparticles to the binder is 0.3-9.5: 1. the content of the metal-organic framework nano particles in the range can effectively improve the heat resistance of the diaphragm and improve the safety performance of the battery in a high-temperature environment; the uniform pore channel structure of the metal-organic framework material coating enables lithium ions to be uniformly deposited/stripped in the charging and discharging processes.

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, bonding the metal-organic framework nanoparticles to the first coating layer and the second coating layer.

In some specific embodiments, a zinc oxide nanowire layer is further disposed between the intermediate layer and the first coating layer or the second coating layer. The zinc oxide nanowire layer has a small intestine villous structure like a finger-shaped protrusion, and can capture fragments of the detached active materials to keep the active materials electrochemically active, so that the active materials can be repeatedly used, and the attenuation percentage of the lithium ion battery is reduced.

In some embodiments, the active material layer includes a lithium transition metal oxide-based active material, which may release lithium ions during charge and discharge of the battery and improve electrochemical activity of the separator.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, so any modifications, equivalent replacements, improvements, etc. made to the above embodiments by the technology of the present invention are all within the scope of the technical solution of the present invention.

Claims

1. A composite diaphragm for a lithium ion battery is characterized in that: the diaphragm comprises a middle layer, wherein the middle layer is of a porous structure, a first coating is arranged on the upper surface of the middle layer, a second coating is arranged on the lower surface of the middle layer, and the first coating and the second coating both contain metal-organic framework nano particles.

2. The composite membrane of claim 1, wherein: the average pore diameter of the intermediate layer is 15-50nm, and the thickness is 5-32 μm.

3. The composite membrane of claim 1, wherein: the thickness of the first coating and the second coating is 0.5-5 μm.

4. The composite membrane of claim 1, wherein: the intermediate layer includes an active material layer therein.

5. The composite membrane of claim 4, wherein: and a zinc oxide nanowire layer is also arranged between the middle layer and the first coating or the second coating.

6. The composite membrane of claim 4 or 5, wherein: the active material layer includes a lithium transition metal oxide-based active material.