WO2023225940A1

WO2023225940A1 - Binder, and insulating film and battery module using same

Info

Publication number: WO2023225940A1
Application number: PCT/CN2022/095240
Authority: WO
Inventors: 陆阳; 祁少伟; 杨献伟; 齐晨; 叶永煌; 任苗苗; 靳超; 李莲华
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2022-05-26
Filing date: 2022-05-26
Publication date: 2023-11-30
Also published as: CN117480673A

Abstract

Provided are a binder, and an insulating film and a battery module using same, wherein the binder comprises: an adhesive, a curing agent, a solvent, and 20-50 wt% of a cyclic oligosaccharide, on the basis of the total weight of the binder. The binder has good bonding capacity, shock resistance and impact resistance, the vibration resistance and impact resistance of the battery module using the binder are significantly improved, the short-circuit phenomenon of a battery pack is significantly reduced, and the safety performance of a vehicle during driving is significantly improved.

Description

Adhesives, insulating films and battery modules using them

Technical field

The present application relates to the technical field of adhesives, and in particular to an adhesive, an insulating film and a battery module using the same.

Background technique

Lithium-ion power batteries are mainly used in electric vehicles. The current common assembly form is: battery modules are composed of battery cells and accessories, and then the battery modules and accessories are composed of battery packs, which are then installed on the vehicle to provide power. Since the vehicle Uncertainty in driving scenarios and possible collisions can easily cause collisions between battery cells and between battery cells and other components in the battery module, thus causing safety accidents.

Therefore, how to solve the safety problem of power batteries during use is an urgent problem in this field.

Contents of the invention

This application was made in view of the above problems, and its purpose is to provide an adhesive, an insulating film using the same, and a battery module, aiming to improve the problem of adhesive failure and improve the vibration resistance and resistance of the battery module. Impact performance.

The first aspect of this application provides an adhesive, which includes:

Adhesive, curing agent, solvent, and 20% to 50% by weight of cyclic oligosaccharide, based on the total weight of the binder.

In any embodiment, the adhesive of the present application includes:

5% to 50% by weight of adhesive, optionally 20% to 40% by weight;

20% to 50% by weight of cyclic oligosaccharide, optionally 25% to 35% by weight;

0.5% to 10% by weight of curing agent, optionally from 1% to 5% by weight; 10% to 40% by weight of solvent, optionally from 15% to 35% by weight; each based on the binder of total weight.

In any embodiment, the cyclic oligosaccharide in the binder of the present application is selected from one or more of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin.

In any embodiment, the adhesive in the adhesive of the present application is selected from one or more of polyvinyl acetate, polyvinyl alcohol, vinyl perchloride, polyisobutylene, cellulose ester and polyacrylic acid; optionally , the number average molecular weight of the adhesive is 1,000-90,000, optionally 5,000-50,000.

In any embodiment, the curing agent in the adhesive of the present application is a polyamide curing agent.

In any embodiment, the solvent in the binder of the present application is selected from one or more of carbon tetrachloride, ethyl acetate, methyl formate, ethanol, and toluene; optionally, the solvent is toluene .

In any embodiment, the binder of the present application also contains cellulose, and the cellulose is selected from the group consisting of hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, One or more of cellulose and carboxymethyl cellulose, optionally, the content of the cellulose is 2% to 25% by weight, optionally 3% to 20% by weight, based on the viscosity The total weight of the binder.

A second aspect of the application provides an insulating film, including a base film and an organic coating located on at least one surface of the base film. The organic coating includes the adhesive described in the first aspect of the application. The organic coating The thickness of the layer is 90μm-300μm, optional 100μm-200μm.

In any embodiment, the base film is made from at least one polymer selected from the group consisting of polyethylene, polyvinyl chloride, polypropylene, and polyethylene terephthalate.

In any embodiment, the base film is a film made of polyethylene terephthalate, and the base film is hydroxylated.

A third aspect of this application provides a battery module, including side-by-side battery cells and end plates and side plates surrounding the battery cells, wherein the battery module meets at least one of the following conditions:

The battery shell of the battery cell is wrapped with the insulating film of the second aspect of the present application;

The battery cells, the battery cells and the side plates, and the battery cells and the end plates are bonded by the adhesive of the first aspect of the present application.

A fourth aspect of the present application provides a battery pack, including the battery module of the third aspect of the present application, and the battery pack serves as a power source for an electrical device.

This application develops an adhesive with excellent bonding ability, earthquake resistance, and impact resistance. The vibration resistance and impact resistance of the battery module using the adhesive are significantly improved, and the short circuit phenomenon in the battery pack is eliminated. Significantly reduce and significantly improve the safety performance of the vehicle during driving.

Possible applications of the adhesive of the present application in battery packs are as follows: First, the adhesive of the present application is used as a coating component to prepare an insulating film, and the insulating film is used to wrap on the surface of the battery cell shell to provide insulation and earthquake resistance; Secondly, when assembling a battery module, the adhesive of the present application serves as an adhesive to bind battery cells and battery cells/battery cells and end plates/battery cells and side plates, further strengthening the battery module. The role of firmness and earthquake resistance. The vibration resistance and impact resistance of the battery pack using the binder are significantly improved, the short circuit phenomenon in the battery pack is significantly reduced, and the safety performance of the vehicle is significantly improved.

Description of the drawings

FIG. 1 is an infrared spectrum of a base film of an insulating film according to an embodiment of the present application.

Figure 2 is an insulating film according to an embodiment of the present application, in which one side of the base film is coated with the adhesive of the present application.

Figure 3 is a schematic diagram of a battery module composed of battery cells according to an embodiment of the present application, in which the battery cell shell is wrapped with an insulating film.

FIG. 4 is a schematic diagram of a battery module assembled into a battery pack according to an embodiment of the present application.

Detailed ways

Hereinafter, embodiments in which the adhesive agent of the present application, the insulating film using the same, and the power battery device are specifically disclosed will be described in detail with reference to the drawings as appropriate. However, unnecessary detailed explanations may be omitted. For example, detailed descriptions of well-known matters may be omitted, or descriptions of substantially the same structure may be repeated. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

"Ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless stated otherwise, the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

If there is no special explanation, the words "include" and "include" mentioned in this application represent open expressions, which may also be closed expressions. For example, "comprising" and "comprising" may mean that other components not listed may also be included or included, or only the listed components may be included or included.

In this application, the term "or" is inclusive unless otherwise specified. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).

In order to increase the stability of the battery cells in the battery module, when the battery modules are composed of battery cells, an adhesive is usually used to bond the battery cells to each other, and then the end plates and side plates are bonded using the adhesive. The plate is fixed to the battery cell. Secondly, in order to increase the insulation between battery cells, the outer shell surface of the battery cells needs to be covered with an insulating film. However, during vehicle use, as the battery pack is exposed to different vibration conditions for a long time, the adhesive may easily fall off, resulting in displacement of the battery cells in the battery module, and in turn, damage to the insulating film on the surface of the battery cell casing. A short circuit between battery cells may cause vehicle safety accidents.

Based on the above technical problems, this application starts from increasing the bonding ability, earthquake resistance, and impact resistance between battery cells in the battery module, and develops an adhesive that has both excellent bonding ability, earthquake resistance, and impact resistance. Binder, the vibration resistance and impact resistance of the battery module using the binder are significantly improved, the short circuit phenomenon in the battery pack is significantly reduced, and the safety performance of the vehicle during driving is significantly improved.

[Binder]

Based on this, the first aspect of the present application provides an adhesive, which includes:

Without being limited to any theory, it is now believed that cyclic oligosaccharides composed of several glucose units bonded with 1,4-glycosidic bonds have a three-dimensional cyclic structure of a hollow cylinder. This three-dimensional cyclic structure makes the cyclic low Glycan molecules can withstand repeated microscopic strains in different directions without structural disintegration. The inner ring edge of cyclic oligosaccharides is mainly composed of C-H bonds and is hydrophobic. This hydrophobic hole can be embedded in long-chain polymer compounds and further decompose microscopic stress by forming a cross-linked network. Therefore, the cyclic oligosaccharide can improve the bonding performance of the binder under long-term vibration and impact strain, so that the battery module has good earthquake resistance and impact resistance.

In some embodiments, the adhesives of the present application include:

5% to 50% by weight of adhesive, optionally 20% to 40% by weight;

20% to 50% by weight of cyclic oligosaccharides, optionally 25% to 35% by weight;

In some embodiments, the content of the cyclic oligosaccharide is 20% to 50% by weight, optionally 25% to 35% by weight, more optionally 28% to 32% by weight, based on the binder. Total weight.

If the content of cyclic oligosaccharides is too high or too low, the bonding effect of the adhesive will be significantly reduced under long-term vibration and impact strain. Only within the appropriate range, the adhesive can maintain good bonding performance and function without failure under long-term vibration and impact strain.

In some embodiments, the cyclic oligosaccharide has the following general formula:

Wherein said R is selected from one or more of hydrogen atom, NH ₂ , C1-C6 alkyl group, C1-C6 alkylcarbonyl group and C1-C6 alkyl hydroxyl group, n is an integer from 0 to 6, optional 1 An integer of -3; optionally, the cyclic oligosaccharide is selected from one or more of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin.

In this application, it can be understood that "C1-C6 alkyl" refers to a straight-chain or branched-chain hydrocarbon with 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl base, isobutyl, sec-butyl, tert-butyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1, 1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4- Methylpentyl, 1,2-dimethylpropyl, 1,3-dimethylbutyl, 1,4-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl Methylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1 -Ethylbutyl and 2-ethylbutyl. Also optional are alkyl groups having 1 to 4 carbon atoms, for example especially methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

The different types of cyclic oligosaccharides can be purchased directly or directly synthesized using existing technical means.

In this application, it will be understood that "an integer from 0 to 6" refers to the integers of 0, 1, 2, 3, 4, 5 and 6.

In some embodiments, β-cyclodextrin with a corresponding number of glucose monomer molecules of 7 and γ-cyclodextrin with a corresponding number of glucose monomer molecules of 8 can also provide good resistance to vibration and impact strain.

Furthermore, when the cyclic oligosaccharide is α-cyclodextrin, the corresponding number of glucose monomer molecules is 6, and its cavity size can allow some long-chain polymers to pass through; when the number of glucose monomer molecules increases When the temperature increases, the cavity size becomes larger, and the vibration and impact strain resistance of cyclodextrin is correspondingly weakened. Therefore, α-cyclodextrin can provide better vibration and impact strain resistance.

In some embodiments, the content of the adhesive is 20% to 50% by weight, optionally 25% to 40% by weight, and optionally 26% to 35% by weight, based on the total weight of the adhesive.

By further adjusting the weight ratio of the adhesive within an appropriate range, the bonding performance of the adhesive can be further improved, thereby improving the vibration resistance and strain resistance of the corresponding battery module.

In some embodiments, the adhesive is selected from one or more of polyvinyl acetate, polyvinyl alcohol, vinyl perchloride, polyisobutylene, cellulose ester and polyacrylic acid.

In some embodiments, the adhesive has a number average molecular weight of 1,000-90,000, optionally 5,000-50,000, and optionally 5,500-20,000.

Keep the molecular weight distribution range of the adhesive within a reasonable range, the better the uniformity of the adhesive, the better the synergy with other components of the adhesive, and the better the adhesive performance and seismic resistance of the adhesive. When the molecular weight is small, the bonding effect between the adhesive molecules and between the adhesive molecules and other components of the adhesive is weaker, and the adhesive cannot function as an adhesive; when the molecular weight is greater than a certain value, the bonding effect of the adhesive cannot be further improved. , there is no significant improvement in improving the performance of the adhesive; in this application, the molecular weight range of the adhesive can be selected from 5500-20000.

In this application, the number average molecular weight is determined by gel permeation chromatography (GPC) method according to GB/T 21863-2008 "Gel permeation chromatography (GPC) using tetrahydrofuran as eluent" (equivalent to the German standard DIN 55672- 1: 2007 "Gel permeation chromatography (GPC) Part 1: Using tetrahydrofuran (THF) as the elution solvent").

In some embodiments, the adhesive has a degree of polymerization of 100-2000, optionally 200-1000, more optionally 300-600.

Keep the degree of polymerization of the adhesive molecules within a reasonable range, the better the uniformity of the adhesive, the better the synergy with other components of the adhesive, and the better the adhesive performance and seismic resistance of the adhesive.

In some embodiments, the adhesive has a viscosity of 5000 mPa·s to 15000 mPa·s.

When the viscosity of the adhesive is too low, the adhesive behaves as a Newtonian fluid and has poor film-forming properties, which may lead to leakage problems when applying glue. When the viscosity is too high, the adhesive has poor dispersion and is prone to agglomeration, which also affects film-forming properties, leading to leakage problems. .

In this application, the viscosity of the adhesive can be tested at 25°C using the rotation method according to the standard GB/T 10247-2008. The specific operation of this standard is as follows: fill the beaker or sample container with the sample to be tested, making sure not to introduce air bubbles, and if necessary, vacuum to eliminate the air bubbles. If the sample is volatile or easily hygroscopic, the beaker or sample container must be sealed during the constant temperature process. Place the prepared sample beaker or sample container into the constant temperature bath and ensure sufficient time to reach the specified temperature. Choose a suitable rotor so that the reading is between 20% and 90% of the maximum range. For the 63# rotor, it should meet the requirements of 1000mpa·s≤viscosity≤10000mpa·s, 20%≤torque percentage≤90%. If the viscosity result is NG, use the 64# rotor, and the following results should be met at the same time: 10000mpa·s<viscosity, 20 %≤torque percentage≤90%. During the test, the rotor groove was flush with the slurry surface. Turn on the motor. After 5 minutes, when the viscosity reading of the instrument stabilizes, stop the motor. After the rotor stops, turn on the motor again for the second test until the deviation of the two consecutive test data from the average value is no more than 3%. The result is the sum of the two measured values. average.

In some embodiments, the binder composition further comprises cellulose selected from the group consisting of hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose One or more of cellulose and carboxymethyl cellulose. Cellulose mainly plays a cross-linking role in the binder of this application, allowing organic molecules such as adhesives, cyclic oligosaccharides, and curing agents to be cross-linked through cellulose, thereby further increasing the bonding performance and earthquake resistance of the binder.

In some embodiments, the content of the cellulose is 2% to 25% by weight, optionally 3% to 20% by weight, optionally 5% to 15% by weight, and optionally 8% to 20% by weight. 12% by weight, based on the total weight of binder.

In some embodiments, the cellulose is hydroxypropyl methylcellulose, which has hydroxyl, propyl, and methyl functional groups on the cellulose chain. Various types of functional groups improve the performance of nanocellulose in the binder. The cross-linking effect makes the adhesive have good adhesion.

In some embodiments, the cellulose has a number average molecular weight of 10,000-30,000, optionally 15,000 to 25,000.

In some embodiments, the cellulose is nanocellulose, and its particle size Dv50 is 10 nm-100 nm, optionally 30 nm-70 nm.

When the Dv50 of nanocellulose is too low, it is not easy to disperse evenly into the binder system, affecting the cross-linking effect, which in turn affects the bonding performance and earthquake resistance of the binder; when the Dv50 of nanocellulose is too high, it is not easy to disperse with the adhesive system. Other polymer components in the binder system fully form a network structure and affect the cross-linking effect.

Furthermore, the Dv50 of nanocellulose is the same as the particle size of α-cyclodextrin (usually 30-70 nm).

In this application, the particle size Dv50 of the nanocellulose can be measured using a laser particle size analyzer (such as Malvern Master Size 3000) with reference to the standard GB/T 19077.1-2016. Among them, the physical definition of Dv50 is as follows:

Dv50: The particle size corresponding to when the cumulative volume distribution percentage of the particles reaches 50%.

Those skilled in the art can understand that cellulose with other particle sizes can also be used and ground to the required particle size as needed. The method of grinding particles is also well known to those skilled in the art.

Without being limited to any theory, the inventor believes that cellulose can be combined with the outer edge of the cyclic oligomer through hydrogen bonding, and then form a cross-linked network through intermolecular interaction with adhesives and curing agents, further allowing the adhesive to It still has good bonding performance under long-term vibration and impact strain conditions.

In some embodiments, the weight ratio of adhesive: cyclic oligosaccharide: cellulose is (1.5-4): (1.5-5): 1, optional (2-3.5): (2-3.5): 1, Also optional is (2.5-3.3): (2.5-3.3): 1.

In some embodiments, the curing agent is a polyamide curing agent, such as Versamid 125 curing agent. Compared with other types of curing agents, amide curing agents have better curing effects and can also give the composition better bonding properties in humid environments.

In some embodiments, the content of the curing agent is 0.5 to 10% by weight, optionally 1 to 5% by weight, more optionally 1.5 to 4% by weight, based on the total weight of the binder.

In some embodiments, the solvent is selected from one or more of carbon tetrachloride, ethyl acetate, methyl formate, ethanol, and toluene.

In some embodiments, the solvent is toluene. Each component of the binder has better dispersion effect in toluene solution and has the best coating performance.

In some embodiments, the solvent is present in an amount of 10 to 40 wt%, optionally 15 to 35 wt%, 20 to 30 wt%, based on the total weight of the binder.

The solvent can promote the dispersion of each component and the occurrence of cross-linking reaction. After coating, the solvent gradually evaporates, causing the adhesive to produce a bonding effect.

[Insulation film]

A second aspect of the application provides an insulating film, including a base film and an organic coating located on at least one surface of the base film. The organic coating includes the binder described in the first aspect of the application. The organic coating The thickness of the coating is 90μm-300μm, optional 100μm-200μm.

In some embodiments, the base film is made from at least one polymer selected from the group consisting of polyethylene, polyvinyl chloride, polypropylene, and polyethylene terephthalate.

In this application, the coating method can be a method commonly used in this field, such as using a doctor blade cast coating method, and the doctor blade gap is adjusted to 50 μm to 260 μm, optionally 100 μm to 200 μm.

In some embodiments, the base film is a polymer film made from a polymer with a number average molecular weight of 20,000 to 30,000.

In some embodiments, the base film has a thickness of 50 μm to 300 μm, optionally 80 μm to 200 μm.

In some embodiments, the base film is hydroxylated.

In this application, the hydroxylation treatment can be carried out in the following manner: coating the hydroxylation reagent on the film surface (the coating thickness can be 100-300 μm), and then heating it at 10°C-50°C, optionally 20°C-30 React at ℃ for 1 to 20 minutes, optionally 5 to 15 minutes, and then wash the treated surface with deionized water to remove the hydroxylation reagent (for example, use pH test paper to measure the membrane surface, and the pH value is considered to be 7.0 to 7.5. Remove hydroxylating reagent). The hydroxylating reagent can be one or more of 10 to 60 wt% NaOH solution and 10 to 60 wt% KOH solution; optionally, the hydroxylating reagent can be 10 wt% to 60 wt% NaOH solution, optionally 20 to 40 wt% NaOH solution.

In some embodiments, the base film can also be pre-treated before being hydroxylated, such as using ethanol and deionized water for surface cleaning.

The introduction of hydroxyl groups under alkaline conditions can avoid the impact of hydroxylation reagent residues on cyclodextrin molecules; a reasonable selection of the concentration range of the alkaline hydroxylation solution can also avoid damage to the basement membrane.

In some embodiments, the base film is made of polyethylene terephthalate (PET). PET membrane has high chemical stability, but there are no hydrophilic groups on the PET molecular chain and has poor compatibility with most polymers; hydroxylation treatment in an alkaline solution can improve the reactivity of the membrane surface, It is beneficial for the adhesive to adhere well to the PET film.

Refer to Figure 2, which is an insulating film of the present application, in which one side of the base film B is coated with the adhesive A of the present application.

[Battery Module]

A third aspect of the present application provides a battery module, which includes side-by-side battery cells and end plates and side plates surrounding the battery cells.

In some embodiments, see Figure 3. Figure 3 is a battery module composed of six battery cells arranged side by side. The battery shell of the battery cells is wrapped with the insulating film of the second aspect of the present application.

In some embodiments, referring to the battery module of FIG. 3 , the bonding between battery cells, between the battery cells and the side plate S, and between the battery cells and the end plate E are achieved through the bonding method of the first aspect of the present application. agent bonding.

This application has no particular limitation on the shape of the battery cell, which can be cylindrical, square or any other shape.

In some embodiments, the number of battery cells contained in the battery module may be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

In some embodiments, the above-mentioned battery modules can also be assembled into a battery pack. See Figure 4. The number of battery modules contained in the battery pack can be one or more. The specific number can be determined by those skilled in the art according to the application and capacity of the battery pack. choose.

The battery pack can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.

[Example]

Examples of the present application are described below. The embodiments described below are illustrative and are only used to explain the present application and are not to be construed as limitations of the present application. If specific techniques or conditions are not specified in the examples, the techniques or conditions described in literature in the field or product instructions will be followed. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

If there are no special instructions, in this application, all operations are performed at normal temperature (25°C) and normal pressure (101kPa).

Example 1-1

【Preparation of adhesive】

The preparation method of the binder is as follows: 30% polyacrylic acid (purchased from McLean, P890197), 30% α-cyclodextrin (purchased from McLean, C804818), 10 % hydroxypropyl methylcellulose (purchased from McLean, H811095), 28% by weight toluene and 2% by weight Versamid 125 curing agent were mixed evenly to obtain the adhesive of Example 1.

[Preparation of insulating film]

Step 1: Pretreat the PET base film (thickness: 100μm). Use ethanol as a cleaning agent, treat it at room temperature (25°C, the same below) for 15 minutes, rinse it with deionized water three times, and dry it naturally at room temperature;

Step 2: Hydroxylate the pretreated PET base film. The specific method is: evenly apply 30% by weight NaOH solution on both sides of the PET base film. After reacting at room temperature for 10 minutes, use deionized water to rinse the PET base film surface until it is neutral (use pH test paper to measure the pH of the lotion. value is 7.0), let it dry naturally at room temperature;

Step 3: Use a scraper to evenly coat the above adhesive on both sides of the PET base film (use a scraper cast machine, adjust the scraper gap to 125 μm), and apply the organic layer to a thickness of 125 μm.

Thus, the insulating film of Example 1 was obtained.

[Preparation of battery module]

1. Prepare the end plates of the battery module and press them tightly on the assembly equipment; 2. Clean the battery cells, side plates and end plates; 3. Cover the surface of the battery cells with the insulating film (except for the connections of the battery cells). part of the top); 4. Assemble the 6 battery cells side by side as shown in Figure 3, so that the battery cells and the battery cells and the end plates fit together; 5. Prepare the side plate assembly and align the side plates with The sides of the 6 battery cells are attached together; 6. After the assembly is completed, the battery module for testing is obtained.

Example 1-2

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: α-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 40%: 20%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 1-3

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: α-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 10%: 50%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Comparative example 1-1

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: α-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 60%: 0%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Comparative Example 1-2

Except in [Preparation of Binder], according to the weight ratio of polyacrylic acid: α-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 10%: 55%: 5%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 2-1

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: β-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 35%: 25%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 2-2

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: β-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 25%: 35%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Comparative Example 1-3

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: α-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 0%: 60%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 3-1

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: γ-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 30%: 30%: 10%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 3-2

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: γ-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 30%: 30%: 2%: 28%: 10% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 3-3

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: γ-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 30%: 30%: 25%: 13%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 3-4

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: γ-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 30%: 30%: 0%: 28%: 12% Except for mixing, other preparation steps are the same as in Example 1-1.

Example 3-5

Except in [Preparation of Binder], follow the weight ratio of polyacrylic acid: γ-cyclodextrin: hydroxypropyl methylcellulose: toluene: Versamid125 = 10%: 30%: 30%: 28%: 2% Except for mixing, other preparation steps are the same as in Example 1-1.

Comparative Examples 1-4

The battery cell casing is only covered with PET base film, and acrylic structural adhesive (brand: 3M, model: DP8805NS) is used between the battery cells in the battery module and between the battery cells and the end plates and side plates.

Comparative Example 1-5

Except that in the [Preparation of Insulating Film] step, the base film is not processed in the first and second steps, other preparation steps are the same as in Example 1-1.

Example 4-1

Except that in [Preparation of Insulating Film], the thickness of the organic coating is 90 μm, other preparation steps are the same as in Example 1-1.

Example 4-2

Except that in [Preparation of Insulating Film], the thickness of the organic coating is 280 μm, other preparation steps are the same as in Example 1-1.

Comparative Example 1-6

Except that in [Preparation of Insulating Film], the thickness of the organic coating is 350 μm, other preparation steps are the same as in Example 1-1.

Comparative Example 1-7

Except that in [Preparation of Insulating Film], the thickness of the organic coating is 50 μm, other preparation steps are the same as in Example 1-1.

[Battery module vibration resistance and impact resistance test]

A universal testing machine (MTS, model: CDT1100) was used to test the battery modules corresponding to all the above embodiments and comparative examples.

Vibration strain test in different directions: Apply vibration strains in the x, y, and z directions of the battery module (see Figure 3). Set the vibration conditions to a vibration frequency range of 100-1500Hz and a high-frequency vibration duration of 8 hours. The vibration acceleration range is 0-100m/s ^2. After the test, disassemble the battery module and record the frequency change amplitude of the battery cells in the tested battery pack before and after vibration. The smaller the change rate, the better the battery module is against vibration. The better the performance;

Impact strain test in different directions: Apply impact strains in the x, y, and z directions of the battery module respectively. Set the impact conditions to a vibration frequency range of 100-1500Hz, a high-frequency impact duration of 6ms, and an impact acceleration range of 0- 500m/s ^2. After the test, disassemble the battery module and record the frequency change amplitude of the battery cells in the tested battery module before and after the impact. The smaller the change rate, the better the impact resistance.

Criteria for judging the seismic performance of battery modules in this application:

If the frequency change rates of the battery cells in the x, y, and z directions before and after vibration are all within ±3%, the battery module is considered to have excellent vibration resistance;

If the frequency change rates of the battery cells in the x, y, and z directions before and after vibration are all within ±10%, the battery module is considered to have good vibration resistance;

If the frequency change rates of the battery cells in the three directions of x, y, and z before and after vibration are two or less and are within ±10%, the battery module is considered to have average vibration resistance;

If three of the battery cell's frequency change rates in the x, y, and z directions before and after vibration are above ±10%, or at least one direction frequency change rate exceeds 20%, the battery module is considered to have poor vibration resistance;

If the frequency change rates of the battery cells in the x, y and z directions before and after the impact are all within ±8%, the battery module is considered to have excellent impact resistance;

If the frequency change rates of the battery cells in the x, y and z directions before and after the impact are all within ±20%, the battery module is considered to have good impact resistance;

If the frequency change rates of the battery cells in the x, y and z directions of the battery cell before and after the impact are two or less and are within ±20%, the battery module is considered to have average impact resistance;

The impact resistance performance of the battery cell is considered to be poor if three of the frequency change rates in the x, y and z directions of the battery cell are above ±20% before and after the impact, or if at least one frequency change rate exceeds 30%.

Table 1 Examples and Comparative Examples Preparation Parameters, Product Parameters, and Performance Parameters

【data analysis】:

The examples and comparative examples in Table 1 respectively evaluate the vibration resistance and impact resistance of the battery module of the present application based on the amount of cyclic oligosaccharide, the amount of adhesive, the amount of cellulose, whether the base film is hydroxylated and the thickness of the insulating film. Research was conducted, as follows:

[The impact of cyclic polymers on the vibration resistance and impact resistance of battery modules]

Through comprehensive analysis of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-2, it can be seen that when the content of the cyclic polymer in the binder of the present application is 20-50% by weight, the vibration resistance of the battery module The performance and impact resistance are both excellent; because the impact resistance conditions are more stringent, the polyacrylic acid content in Examples 1-3 is 10% by weight. At this ratio, the adhesive performance is slightly weaker, so the impact resistance is good. .

The cyclic polymer content in the comparative example is outside the appropriate content. The cyclic polymer content in the comparative example 1-1 is 0% by weight, which cannot increase the vibration and impact resistance of the binder. The comparative example 1-2 The proportion of cyclic polymer content is too high and the proportion of polyacrylic acid is too low, resulting in poor bonding performance of the adhesive. Although it has certain vibration resistance, it cannot pass the impact resistance test.

[The impact of adhesives on the vibration resistance and impact resistance of battery modules]

Through comprehensive analysis of Examples 2-1 to 2-3 and Comparative Example 1-3, it can be seen that when the content of polyacrylic acid in the adhesive of the present application is 20-40% by weight, the adhesive exhibits excellent vibration resistance and resistance to vibration. Impact performance: In Comparative Examples 1-3, the proportion of polyacrylic acid is 0% by weight, and the adhesive has poor bonding effect, so its vibration resistance and impact performance are both poor.

[The impact of cellulose on the vibration resistance and impact resistance of battery modules]

Comparing Examples 3-1 to 3-5, it can be seen that the appropriate proportion of cellulose in the binder of the present application is 2-25% by weight. Within this range, the binder exhibits excellent or good vibration resistance and impact resistance. Performance: In Example 3-4, the proportion of cellulose is 0% by weight, and the binding effect of the binder is slightly weak, so its impact resistance is average. In Example 3-5, the proportion of cellulose is 30% by weight and the proportion of polyacrylic acid is At 10% by weight, the proportion of cellulose is too high and the proportion of polyacrylic acid is too low. Cellulose also cannot play a role in strengthening the adhesiveness, so its impact resistance is average.

[Analysis of changes in insulation film thickness]

Comparing Examples 4-1 to 4-2 and Comparative Examples 1-6 and 1-7, it can be seen that the appropriate thickness of the organic coating on the insulating film of the present application is 90-280 μm, and the thickness of the battery cell covered with the insulating film is The battery module showed good vibration resistance and impact resistance; when the thickness of the insulating film was further reduced to 50 μm (Comparative Examples 1-7), the adhesive layer was too thin, affecting its bonding effect, and the thickness increased to 350 μm (for Comparative Examples 1-7). Ratios 1-6), the adhesive layer is too thick and is prone to bonding failure. In these two ratios, the vibration and impact resistance of the adhesive are average.

For example, in Comparative Examples 1-4, the battery module obtained by bonding battery cells to battery cells using conventional acrylic structural adhesive has poor impact resistance and vibration performance;

As shown in Comparative Examples 1-5, when the base film is not hydroxylated, the impact resistance and vibration resistance of the corresponding battery module are average. As shown in Figure 1, in the infrared spectrum of the binder of Example 1-1, there is an obvious absorption vibration peak of hydroxyl group at the wave number of 3600 cm ^-1 , while the non-hydroxylated binder of Comparative Example 1-5 has only a wave number of 3600 cm ^-1 . Weaker hydroxyl absorption vibration peaks, and more hydroxyl functional groups are beneficial to the bonding between the binder component in the organic coating and the hydroxyl groups on the surface of the base film.

Claims

A binder comprising:

Adhesive, curing agent, solvent, and 20% to 50% by weight of cyclic oligosaccharide, based on the total weight of the binder.
The adhesive according to any one of claims 1 to 3, comprising:

5% to 50% by weight of adhesive, optionally 20% to 40% by weight;

20% to 50% by weight of cyclic oligosaccharide, optionally 25% to 35% by weight;

0.5% to 10% by weight of curing agent, optionally from 1% to 5% by weight; 10% to 40% by weight of solvent, optionally from 15% to 35% by weight; each based on the binder of total weight.
The adhesive according to claim 1 or 2, wherein the cyclic oligosaccharide is selected from one or more of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin.
The adhesive according to any one of claims 1 to 3, wherein the adhesive is selected from one of polyvinyl acetate, polyvinyl alcohol, perchlorethylene, polyisobutylene, cellulose ester and polyacrylic acid. Or several; optionally, the number average molecular weight of the adhesive is 1,000-90,000, optionally 5,000-50,000.
The adhesive according to any one of claims 1 to 4, wherein the curing agent is a polyamide curing agent.
The adhesive according to any one of claims 1 to 5, wherein the solvent is selected from one or more of carbon tetrachloride, ethyl acetate, methyl formate, ethanol, and toluene; optional Land, the solvent is toluene.
The binder according to any one of claims 1 to 6, wherein the binder further comprises cellulose selected from the group consisting of hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose One or more of cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose, optionally, the content of the cellulose is 2 to 25% by weight, optionally 3 % by weight to 20% by weight, based on the total weight of the binder.
An insulating film, including a base film and an organic coating located on at least one surface of the base film, the organic coating including the adhesive described in claims 1 to 7, and the thickness of the organic coating being 90 μm -300μm, optional 100μm-200μm.
The insulating film according to claim 8, wherein the base film is made of at least one polymer selected from the group consisting of polyethylene, polyvinyl chloride, polypropylene and polyethylene terephthalate.
The insulating film according to any one of claims 8 or 9, wherein the base film is a film made of polyethylene terephthalate, and the base film is hydroxylated.
A battery module includes side-by-side battery cells and end plates and side plates surrounding the battery cells, wherein the battery module meets at least one of the following conditions:

The battery casing of the battery cell has the insulating film described in claims 8 to 10;

The battery cells, the battery cells and the side plates, and the battery cells and the end plates are bonded by the adhesive described in claims 1 to 7.
A battery pack, including the battery module according to claim 11, the battery pack serves as a power source for an electrical device.