阅读说明：本技术 一种隔膜及其制备方法和应用 (Diaphragm and preparation method and application thereof ) 是由 李欣 陈辉 岳娟 徐嘉辉 于 2021-08-13 设计创作，主要内容包括：本发明涉及一种隔膜及其制备方法和应用,所述隔膜包括隔膜基层以及设置于所述隔膜基层上表面的沸石咪唑酯涂层；以所述沸石咪唑酯涂层的材料的总重量份数为100份计,所述沸石咪唑酯涂层的材料按照重量份数包括如下组分：55-90份ZIF-67,0.1-15份润湿剂,0.1-15份增稠剂和0.1-15份粘结剂。本发明所述隔膜在隔膜基材较薄的前提下,兼具高热稳定性和对电解液的保液量优异的隔膜。(The invention relates to a diaphragm and a preparation method and application thereof, wherein the diaphragm comprises a diaphragm base layer and a zeolite imidazole ester coating arranged on the upper surface of the diaphragm base layer; the zeolite imidazolate coating material comprises the following components in parts by weight, based on 100 parts by weight of the zeolite imidazolate coating material: 55-90 parts of ZIF-67, 0.1-15 parts of wetting agent, 0.1-15 parts of thickening agent and 0.1-15 parts of binder. The diaphragm provided by the invention has high thermal stability and excellent electrolyte retention on the premise that the diaphragm base material is thin.)

1. A membrane, comprising a membrane substrate and a zeolite imidazate coating layer disposed on an upper surface of the membrane substrate;

the zeolite imidazolate coating material comprises the following components in parts by weight, based on 100 parts by weight of the zeolite imidazolate coating material: 55-90 parts of ZIF-67, 0.1-15 parts of wetting agent, 0.1-15 parts of thickening agent and 0.1-15 parts of binder.

2. The separator according to claim 1, wherein the thickness of the separator base layer is 3 to 8 μm;

preferably, the thickness of the zeolitic imidazolate coating is from 1 to 10 μm.

3. The membrane of claim 1, wherein the material of the membrane substrate layer comprises any one of polyethylene, polypropylene, non-woven fabric, polyimide, or cellulose, or a combination of at least two thereof;

preferably, the D50 particle size of the ZIF-67 is 0.5-1 μm.

4. The separator of claim 1, wherein the wetting agent comprises sodium dodecylbenzene sulfonate and/or fatty alcohol polyoxyethylene ether.

5. Separator according to claim 1, characterized in that the thickener comprises sodium and/or lithium carboxymethyl cellulose.

6. The separator of claim 1, wherein the binder comprises any one of or a combination of at least two of styrene butadiene rubber, an acrylate based binder, or an acrylamide based binder.

7. A method for preparing a membrane according to any one of claims 1 to 6, characterized in that it comprises the following steps:

(1) dissolving a first wetting agent in water, uniformly mixing the obtained wetting agent solution with ZIF-67, a thickening agent and a binder in sequence, and mixing the obtained mixed solution with a second wetting agent to obtain zeolite imidazole ester coating slurry;

(2) and (2) coating the zeolite imidazole ester coating slurry obtained in the step (1) on a diaphragm base layer, and drying to form the zeolite imidazole ester coating to obtain the diaphragm.

8. The method for preparing a separator according to claim 7, wherein the mass concentration of the zeolite imidazolate coating slurry is 2 to 80%.

9. A lithium ion battery, characterized in that the lithium ion battery comprises a positive electrode plate, the separator of any one of claims 1 to 6, a negative electrode plate and an electrolyte.

10. A method for preparing a lithium ion battery according to claim 9, characterized in that the method comprises the following steps:

and (3) winding the positive pole piece, the diaphragm of any one of claims 1 to 6 and the negative pole piece into a winding core, sealing the winding core in an aluminum plastic film, and injecting an electrolyte into the aluminum plastic film to obtain the lithium ion battery.

Technical Field

The invention relates to the technical field of batteries, in particular to a diaphragm and a preparation method and application thereof.

Background

At present, the requirements on the quick charge performance and the capacity density of the lithium ion battery are gradually improved, and the development of the lithium ion battery with the quick charge capacity and the larger capacity density is very important. The diaphragm is used as four main materials of the lithium ion battery, the performance of the diaphragm directly influences the safety of the battery, and meanwhile, the performance of the battery core is further optimized on the premise that the safety of the diaphragm is not influenced by developing a new diaphragm functional coating.

CN109950455A discloses a preparation method of a modified diaphragm of a lithium-sulfur battery, which comprises the steps of coating a layer of acidified multi-walled carbon nanotube-coated mesoporous carbon composite material on the surface of a diaphragm substrate; the mesoporous carbon and the groups such as carboxyl, hydroxyl and the like carried by the acidified multi-walled carbon nano-tube in the disclosed composite material can effectively adsorb lithium polysulfide which is an intermediate product of a lithium-sulfur battery anode material in the charging and discharging process, the shuttle effect of the lithium polysulfide between the anode and the cathode is relieved, and the existence of the multi-walled carbon nano-tube can greatly improve the whole conductivity of the lithium-sulfur battery, so that the electrochemical performance of the lithium-sulfur battery is improved. And due to the use of the modified diaphragm, the active elemental sulfur can be used as the positive electrode material of the lithium-sulfur battery without a conductive matrix loaded with the active sulfur, so that the percentage content of the active sulfur in the whole electrode is improved, and the energy density of the lithium-sulfur battery is further improved. However, the preparation process of the modified diaphragm is complex and the cost is high.

CN110729439A discloses a preparation method of a coating-type MOFs/organic composite membrane. Metal-organic frameworks (MOFs), also known as porous coordination polymers, are coordination polymers formed by self-assembly of Metal ions or Metal clusters and corresponding organic ligands through strong coordination bonds. The MOFs disclosed by the method is directly coated on the surface of a polyolefin (polypropylene PP, polyethylene PE and the like) diaphragm, and compared with an organic diaphragm, the MOFs/organic composite diaphragm has good electrolyte wettability, high-temperature stability, higher discharge capacity and better cycle stability. The MOFs/organic composite diaphragm is proved to be a promising battery diaphragm material, a new way is opened for improving the safety of the lithium ion battery, and the disclosed diaphragm is complex to prepare and does not improve the liquid retention capacity of electrolyte.

As described above, it is important to develop a separator having both high thermal stability and excellent liquid retention in an electrolyte solution on the premise that the separator base material is thin.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a diaphragm, a preparation method and an application thereof, wherein the diaphragm has high thermal stability and excellent electrolyte retention capacity on the premise of thinner base material of the diaphragm.

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

in a first aspect, the present invention provides a separator comprising a separator base layer and a zeolite imidazate coating layer disposed on an upper surface of the separator base layer;

the zeolite imidazolate coating material comprises the following components in parts by weight, based on 100 parts by weight of the zeolite imidazolate coating material: 55-90 parts of ZIF-67, 0.1-15 parts of wetting agent, 0.1-15 parts of thickening agent and 0.1-15 parts of binder.

The invention directly adopts ZIF-67 as a matrix material to form the zeolite imidazolate coating which is arranged on the diaphragm substrate as the diaphragm coating, and the formed coating has low probability of introducing impurity metal ions and introduced Co because the coating has a porous imidazole ester framework structure and metal nodes of the coating are Co²⁺The probability of initiating side reactions is low, so that the diaphragm has high thermal stability and excellent electrolyte retention on the premise that the diaphragm base material is thin, the diaphragm is a high-dynamic diaphragm, and the formed lithium ion battery has good battery rate performance and battery cycle performance.

The ZIF-67 is 55-90 parts by weight, such as 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts and the like.

The wetting agent is 0.1-15 parts by weight, such as 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts and the like.

The weight portion of the thickening agent is 0.1-15 portions, such as 1 portion, 2 portions, 3 portions, 4 portions, 5 portions, 6 portions, 7 portions, 8 portions, 9 portions, 10 portions, 11 portions, 12 portions, 13 portions, 14 portions and the like.

The binder is 0.1-15 parts by weight, such as 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts and the like.

Preferably, the ZIF-67 is present in an amount of 80 to 90 parts by weight, such as 82 parts, 84 parts, 86 parts, 88 parts, etc.

Preferably, the thickness of the separator base layer is 3 to 8 μm, such as 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, and the like.

Preferably, the thickness of the zeolitic imidazolate coating is 1-10 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and the like.

The thickness of the zeolite imidazole ester coating is 1-10 mu m, the multiplying power is better when the coating thickness is smaller, but the cycle performance is influenced when the coating thickness is too small, and the coating thickness is more than 20% of the thickness of the base layer, so that a better supporting effect can be achieved.

Preferably, the material of the membrane substrate comprises any one of polyethylene, polypropylene, non-woven fabric, polyimide or cellulose or a combination of at least two thereof, wherein typical but non-limiting combinations include: combinations of polyethylene and polypropylene, nonwoven and polyimide, polypropylene, nonwoven, polyimide and cellulose, and the like.

Preferably, the D50 particle size of ZIF-67 is 0.5-1 μm, e.g., 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, etc.

The D50 particle size of the ZIF-67 is 0.5-1 mu m, the rate capability and the cycle performance can be reduced when the D50 particle size is too small, and a zeolite imidazole ester coating formed by the ZIF-67 with the particle size range has proper air permeability while achieving better thermal stability, and is beneficial to the passing of lithium ions.

Preferably, the wetting agent comprises sodium dodecyl benzene sulfonate and/or fatty alcohol-polyoxyethylene ether.

Preferably, the thickener comprises sodium carboxymethyl cellulose and/or lithium carboxymethyl cellulose.

Preferably, the binder comprises any one or a combination of at least two of styrene-butadiene rubber, an acrylate-based adhesive or an acrylamide-based adhesive, wherein typical but non-limiting combinations include: a combination of styrene-butadiene rubber and an acrylate adhesive, a combination of an acrylate adhesive and an acrylamide adhesive, a combination of styrene-butadiene rubber, an acrylate adhesive and an acrylamide adhesive, and the like.

In a second aspect, the present invention provides a method for producing the separator of the first aspect, the method comprising the steps of:

(1) dissolving a first wetting agent in water, uniformly mixing the obtained wetting agent solution with ZIF-67, a thickening agent and a binder in sequence, and mixing the obtained mixed solution with a second wetting agent to obtain zeolite imidazole ester coating slurry;

(2) and (2) coating the zeolite imidazole ester coating slurry obtained in the step (1) on a diaphragm base layer, and drying to form the zeolite imidazole ester coating to obtain the diaphragm.

According to the preparation method, the ZIF-67 is directly adopted, the process is simple and easy to operate, the wetting agent is divided into two parts, the first wetting agent enables the later-added adhesive to be uniformly spread on the surface of the ZIF-67, the second wetting agent enhances the dispersibility of the adhesive, the uniformity of the zeolite imidazole ester coating slurry is improved, and the finally obtained diaphragm is uniform and stable in performance.

Preferably, the mass concentration of the zeolite imidazolate coating slurry is 2% to 80%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc., and more preferably 25% to 40%, which facilitates the formation of a stable and uniform coating slurry uniformly coated on the substrate. The mass concentration here refers to the total mass concentration of all solutes.

In a third aspect, the present invention provides a lithium ion battery, which includes a positive electrode plate, the diaphragm of the first aspect, a negative electrode plate, and an electrolyte.

In a fourth aspect, the present invention provides a method for preparing the lithium ion battery of the third aspect, including the following steps:

and winding the positive electrode plate, the diaphragm and the negative electrode plate into a winding core, sealing the winding core in an aluminum plastic film, and injecting an electrolyte to obtain the lithium ion battery.

Compared with the prior art, the invention has the following beneficial effects:

the diaphragm is a high-dynamics diaphragm, has high thermal stability and excellent electrolyte retention capacity on the premise of thinner base material of the diaphragm, and the formed lithium ion battery has better battery rate performance and battery cycle performance. The MD shrinkage rate is less than 1.93%, the TD shrinkage rate is less than 1.30%, the 1C capacity retention rate is more than 92.15%, the 1.5C capacity retention rate is more than 88.36%, the 2C capacity retention rate is more than 86.04%, the capacity retention rate of 500 cycles at room temperature is more than 89.64%, the capacity retention rate of 500 cycles at 45 ℃ is more than 87.23%, and the liquid retention capacity of the electrolyte is more than 4.75 g.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

This example provides a separator comprising a separator base layer (4 μm thick, polyethylene available from chongqing nim under the trade designation H-HP5) and a zeolite imidazolate coating (2 μm thick);

the zeolite imidazole ester coating material comprises the following components in parts by weight: 80 parts of ZIF-67(D50 with the particle size of 1 mu m, purchased from Xifeng nanometer and the brand number of XFF15), 6.6 parts of wetting agent (sodium dodecyl benzene sulfonate and fatty alcohol polyoxyethylene ether with the mass ratio of 1: 1), 6.7 parts of thickening agent (sodium carboxymethyl cellulose, purchased from Japan paper making and the brand number of MAC500LC) and 6.7 parts of binder (acrylate binder, purchased from Yindele and the brand number of LA 168B).

The preparation method of the diaphragm comprises the following steps:

(1) dissolving a first wetting agent (sodium dodecyl benzene sulfonate) in water, sequentially and uniformly mixing the obtained wetting agent solution with ZIF-67, a thickening agent and a binder, and then mixing the obtained mixed solution with a second wetting agent (fatty alcohol-polyoxyethylene ether) to obtain zeolite imidazole ester coating slurry with the mass concentration of 65%;

(2) and (2) coating the zeolite imidazole ester coating slurry obtained in the step (1) on a diaphragm base layer, and drying to form the zeolite imidazole ester coating to obtain the diaphragm.

Examples 2 to 5

Examples 2 to 5 are different from example 1 in that D50 particle diameters of ZIF-67 were 0.5. mu.m, 0.8. mu.m, 0.25. mu.m and 1.2. mu.m, respectively, and the rest was the same as example 1.

Examples 6 to 9

Examples 6-9 differ from example 1 in that the thickness of the zeolitic imidazolate coating was 1 μm, 10 μm, 0.5 μm and 15 μm, respectively, all as in example 1.

Example 10

The difference between this example and example 1 is that the wetting agent is not divided into two parts in the preparation method, and all wetting agents are directly prepared into a solution for subsequent operations, and the rest is the same as example 1.

Examples 11 to 12

Examples 11-12 differ from example 1 in the parts by weight of ZIF-67 in the zeolitic imidazolate coating material, the remaining three components being adjusted accordingly, the remainder being the same as in example 1;

in example 11, the material of the zeolite imidazate coating comprises the following components in parts by weight: 90 parts of ZIF-67 (the particle size of D50 is 1 mu m), 3.3 parts of wetting agent, 3.3 parts of thickening agent and 3.4 parts of binder;

in example 12, the material of the zeolite imidazate coating comprises the following components in parts by weight: 67 parts of ZIF-67(D50 particle size 1 μm), 11 parts of wetting agent, 11 parts of thickening agent and 11 parts of binder.

Example 13

This example provides a separator comprising a separator base layer (5 μm thick, polypropylene available from chongonim under the trademark HPP5) and a zeolite imidazolate coating (3 μm thick);

the zeolite imidazole ester coating material comprises the following components in parts by weight: 55 parts of ZIF-67(D50 with the particle size of 1 mu m, purchased from Xifeng nanometer and the brand number of XFF15), 15 parts of wetting agent (sodium dodecyl benzene sulfonate and fatty alcohol polyoxyethylene ether with the mass ratio of 2: 1), 15 parts of thickening agent (lithium carboxymethyl cellulose and sodium carboxymethyl cellulose with the mass ratio of 1:1, lithium carboxymethyl cellulose with the mass ratio of L-H109, sodium carboxymethyl cellulose with the mass ratio of MAC500LC and manufactured from Japanese paper) and 15 parts of binding agent (styrene butadiene rubber and acrylamide binding agent with the mass ratio of 2:1, styrene butadiene rubber with the brand number of LB300 and acrylamide binding agent with the brand number of MS-JBXXA19 and manufactured from Guangxi American environmental science and technology).

The preparation method of the diaphragm comprises the following steps:

(1) mixing two wetting agents to divide the two wetting agents into two parts with the mass ratio of 2:1, dissolving the first part of wetting agents in water, then sequentially and uniformly mixing the obtained wetting agent solution with ZIF-67, a thickening agent and a binder, and then mixing the obtained mixed solution with the second part of wetting agents to obtain zeolite imidazole ester coating slurry with the mass concentration of 2%;

(2) and (2) coating the zeolite imidazole ester coating slurry obtained in the step (1) on a diaphragm base layer, and drying to form the zeolite imidazole ester coating to obtain the diaphragm.

Example 14

The embodiment provides a diaphragm, which comprises a diaphragm base layer (12 μ M thick, polypropylene, polyethylene and polypropylene three-layer composite diaphragm with a mass ratio of 1: 1: 1), a Shenzhen Shencheng Shenhui electron with a trade name of 12M-001, and a zeolite imidazole ester coating (10 μ M thick);

the zeolite imidazole ester coating material comprises the following components in parts by weight: 85 parts of ZIF-67(D50 particle size 1 μm, available from Xiifeng nanometer under the trade name XFF15), 10 parts of wetting agent (sodium dodecylbenzenesulfonate), 0.1 part of thickener (lithium carboxymethyl cellulose available from Suzhou Rehong under the trade name L-H109;) and 4.9 parts of binder (acrylamide adhesive available from Guangxi Meishi environmental science under the trade name MS-JBXXA 19).

The preparation method of the diaphragm comprises the following steps:

(1) dividing a wetting agent into two parts with the mass ratio of 1:2, dissolving the wetting agent of the first part in water, then sequentially and uniformly mixing the wetting agent solution with ZIF-67, a thickening agent and a binder, and then mixing the mixed solution with the wetting agent of the second part to obtain zeolite imidazole ester coating slurry with the mass concentration of 80%;

(2) and (2) coating the zeolite imidazole ester coating slurry obtained in the step (1) on a diaphragm base layer, and drying to form the zeolite imidazole ester coating to obtain the diaphragm.

Comparative example 1

This comparative example is different from example 1 in that ZIF-67 was replaced with an equal weight part of alumina having a D50 particle size of 1 μm, and the rest was the same as example 1.

Comparative example 2

This comparative example is different from example 1 in that ZIF-67 was replaced with ZIF-8 in an equal weight part, and D50 particle size of ZIF-8 was 1 μm, and the rest was the same as example 1.

Comparative example 3

The difference between the comparative example and the example 1 is that the weight parts of ZIF-67 in the material of the zeolite imidazolate coating are different, the other three components are correspondingly adjusted, and the rest components are the same as the example 1;

the zeolite imidazole ester coating material comprises the following components in parts by weight: 94 parts of ZIF-67 (the particle size of D50 is 1 mu m), 2 parts of wetting agent, 2 parts of thickening agent and 2 parts of binder.

Performance testing

The separators described in examples 1 to 14 and comparative examples 1 to 3, the positive electrode plate and the negative electrode plate were wound to form a winding core, an aluminum plastic film was sealed, and an electrolyte was injected to form a 4.35V, 3Ah capacity lithium ion battery, and the obtained lithium ion battery was tested as follows:

(1) heat shrinkage performance:

making the diaphragm into side length A₀Square of (2), the membrane was placed in a constant temperature oven for 1h, and the length in the MD and TD directions was measured as A₁And A₂Due to the factThe thermal shrinkage of this separator was:

MD heat shrinkage: 1-A₁/A₀；

MD heat shrinkage: 1-A₂/A₀。

(2) Battery rate capability:

and (3) testing temperature: 23 +/-2 ℃;

laying aside for 5 min;

discharging the mixture to 3.0V at constant current of 0.5C, and standing for 5 min;

③ charging to 4.35V at 0.5C with constant current and constant voltage, cutting off the current at 0.02C, and standing for 5 min;

XC discharges at constant current (wherein X is 1, 1.5 and 2) to 3.0V, records discharge capacity C and time T, and stands for 5 min;

and fifthly, repeating the 3-4 steps for 2 times to complete the discharge with 3 different multiplying powers in the 4 steps.

(3) The battery cycle performance is as follows:

and (3) testing temperature: 23 +/-2 ℃/45 +/-2 ℃;

testing initial voltage, internal resistance and thickness in a half-electric state;

charging to 4.35V at constant current and constant voltage of 0.5C, stopping current of 0.05C, and standing for 5 min;

③ discharging the mixture to 3.0V at constant current of 0.5C, and standing for 5 min;

fourthly, charging the battery to 4.35V at constant current and constant voltage of 0.5C, cutting off the current of 0.05C, and standing for 5 min;

repeating the steps for 3-4 times for 500 times, and taking down every 100 weeks to test the voltage, the internal resistance and the thickness in the full-electricity state.

(4) Retention amount of electrolyte:

the diaphragm, the positive pole piece and the negative pole piece are made into a roll core by a winding method, and the roll core is sealed in an aluminum plastic film and injected with electrolyte M₀The liquid retention of the packaged battery is M₁。

The test results are summarized in tables 1-3.

TABLE 1

	MD Heat shrinkage (%)	TD Heat shrinkage (%)
			Example 1	1.15	0.95
Example 2	1.78	1.18
			Example 3	1.63	1.10
Example 4	1.86	1.30
			Example 5	1.02	0.92
Example 6	1.18	1.05
			Example 7	1.04	0.90
Example 8	1.84	1.19
			Example 9	0.98	0.85
Example 10	1.93	1.21
			Example 11	1.05	0.88
Example 12	1.87	1.14
			Example 13	1.35	1.17
Example 14	1.03	1.76
			Comparative example 1	2.67	2.12
Comparative example 2	2.02	1.39
			Comparative example 3	2.04	1.41

The thermal shrinkage of the separator can indicate the thermal stability, and the larger particle size and the thicker coating can make the thermal stability stronger, but on the other hand, the porosity is reduced, and the lithium ion transfer is influenced, so that the electrochemical performance of the battery is influenced. Analysis of the data in table 1 shows that the thermal shrinkage rates in MD and TD are not consistent, the MD shrinkage rate is less than 1.93%, and the TD shrinkage rate is less than 1.30%.

As can be seen from the analysis of comparative examples 1-2 and example 1, comparative examples 1-2 are inferior to example 1 in performance, and it is proved that the separator obtained by using ZIF-67 as a raw material is more favorable for improving the thermal stability.

Analysis of examples 1-2 and 4-5 shows that the thermal shrinkage of the separator decreases with increasing particle size of D50 of ZIF-67, but too large or too small particle size affects lithium ion transport and battery performance, while D50 of ZIF-67 has particle size in the range of 0.5-1 μm, TD shrinkage and MD shrinkage are maintained in low ranges, and therefore lithium ion transport is not affected, and the obtained separator is more beneficial to improving lithium ion battery performance.

Analysis examples 6-9 show that, as the thickness of the coating increases, the thermal shrinkage rate decreases, which is beneficial to improving the thermal stability, but the risk of obstructing the lithium ion transfer may exist to reduce the performance of the battery, while the coating is less than 1 μm, the thermal shrinkage rate of the diaphragm is large, the safety risk of the battery is greatly increased, and the diaphragm obtained by coating the zeolite imidazole ester with the thickness of 1-10 μm can ensure the safety and improve the performance of the lithium ion battery.

As can be seen from the analysis of example 10 and example 1, example 10 is inferior in thermal stability to example 1, and the batch addition of the wetting agent is more beneficial to improving the thermal stability of the separator and the performance of the lithium ion battery.

As can be seen from the analysis of examples 1, 11 to 12 and comparative example 3, example 12 and comparative example 3 were inferior in thermal stability to examples 1 and 11, and it was confirmed that the separator obtained with the ZIF-67 in the range of 80 to 90 parts by weight was more advantageous in the improvement of the performance of the lithium ion battery.

TABLE 2

The data in table 2 are analyzed, and it can be seen that the higher the capacity retention rate in different rate discharges is, the better the dot performance is, after the diaphragm of the present invention is prepared into a lithium ion battery, the 1C capacity retention rate is above 92.15%, the 1.5C capacity retention rate is above 88.36%, the 2C capacity retention rate is above 86.04%, and the rate performance is better.

As can be seen from the analysis of comparative examples 1-2 and example 1, the performance of comparative examples 1-2 is inferior to that of example 1, and the fact that the diaphragm obtained by taking ZIF-67 as a raw material is more beneficial to lithium ion transportation and improves the rate performance of the battery is proved.

As can be seen from the analysis of examples 1-2 and 4-5, the performance of examples 4-5 is not as good as that of examples 1-2, and the fact that the transportation of lithium ions is affected when the particle size is too large or too small is proved, the rate performance of the battery is reduced, the transportation of lithium ions is not affected when the D50 particle size of ZIF-67 is within the range of 0.5-1 μm, and the obtained separator is more beneficial to the improvement of the performance of the lithium ion battery.

Analysis examples 6-9 show that the lithium ion transfer capacity is gradually reduced with the increase of the coating thickness, and although the rate performance of the separator with the coating of 0.5 μm is the best, the thermal shrinkage rate of the separator is larger, and the safety risk of the battery is greatly increased, so that the separator with the thickness of the zeolite imidazole ester coating in the range of 1-10 μm can ensure the safety and improve the performance of the lithium ion battery.

As can be seen from the analysis of example 10 and example 1, example 10 is inferior in performance to example 1, and the batch addition of the wetting agent to the obtained separator is more advantageous for the improvement of the performance of the lithium ion battery.

As can be seen from the analysis of examples 1, 11 to 12 and comparative example 3, example 12 and comparative example 3 were inferior in performance to examples 1 and 11, and it was confirmed that the separator obtained with the ZIF-67 in the range of 80 to 90 parts by weight was more advantageous in the improvement of the performance of the lithium ion battery.

TABLE 3

Analysis of data in table 3 shows that after 500 cycles at room temperature and 45 ℃, the capacity retention rate of the battery is higher, and the performance of the battery is better, after the diaphragm disclosed by the invention is prepared into a lithium ion battery, the capacity retention rate of 500 cycles at room temperature is more than 89.64%, the capacity retention rate of 500 cycles at 45 ℃ is more than 87.23%, the liquid retention capacity of the electrolyte is more than 4.75g, and the cycle performance and the liquid retention capacity of the electrolyte are both better.

As can be seen from the analysis of comparative examples 1-2 and example 1, the performance of comparative examples 1-2 is inferior to that of example 1, and the fact that the diaphragm obtained by taking ZIF-67 as a raw material is more beneficial to lithium ion transportation and improves the cycle performance of the battery is proved.

As can be seen from the analysis of examples 1-2 and 4-5, the performance of examples 4-5 is not as good as that of examples 1-2, and the fact that the transportation of lithium ions is affected when the particle size is too large or too small is proved, the cycle performance of the battery is reduced, the transportation of lithium ions is not affected when the D50 particle size of ZIF-67 is within the range of 0.5-1 μm, and the obtained separator is more beneficial to the improvement of the performance of the lithium ion battery.

Analysis of examples 6-9 shows that examples 8-9 are inferior to examples 6-7, and that the cycle performance of the battery is affected by too large or too small a coating thickness, and the performance of the lithium ion battery is improved by the separator obtained by the thickness of the zeolite imidazole ester coating in the range of 1-10 μm.

As can be seen from the analysis of example 10 and example 1, example 10 is inferior in performance to example 1, and the batch addition of the wetting agent to the obtained separator is more advantageous for the improvement of the performance of the lithium ion battery.

As can be seen from the analysis of examples 1, 11 to 12 and comparative example 3, example 12 and comparative example 3 were inferior in performance to examples 1 and 11, and it was confirmed that the separator obtained with the ZIF-67 in the range of 80 to 90 parts by weight was more advantageous in the improvement of the performance of the lithium ion battery.

In conclusion, the diaphragm provided by the invention has high thermal stability and excellent electrolyte retention on the premise that the diaphragm base material is thin, and the formed lithium ion battery has better battery rate performance and battery cycle performance.

The present invention is illustrated in detail by the examples described above, but the present invention is not limited to the details described above, i.e., it is not intended that the present invention be implemented by relying on the details described above. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.