Electrochemical battery packaging material and preparation method thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an electrochemical battery packaging material and a preparation method thereof. The electrochemical battery packaging material is prepared from the following components in parts by mass: 20 to 30 parts of styrene block copolymer, 20 to 30 parts of maleic anhydride grafted modified styrene-ethylene / butylene-styrene, 20 to 50 parts of synergistic resin, 1 to 2 parts of cross-linking agent, 1 to 2 parts of silane coupling agent, 1 to 2 parts of antioxidant and 300 to 350 parts of solvent. The prepared electrochemical battery packaging material is excellent in comprehensive performance, and is a novel electrochemical battery packaging material with high tensile strength, excellent aging resistance and good comprehensive performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to an electrochemical battery packaging material and a preparation method thereof. BACKGROUND

[0002] With the transformation of global energy structure and the in-depth promotion of sustainable development strategy, electrochemical energy storage technology plays an increasingly key role in new energy vehicles, renewable energy grid connection, smart grids, and portable electronic devices. As a core component of electrochemical energy storage systems, the performance, safety, and life of batteries directly determine the reliability and economy of the entire system. Among the many components of batteries, packaging materials, as the key barrier directly contacting the active materials inside the battery and isolating the external environment, have a decisive impact on the overall performance of the battery.

[0003] Currently, mainstream electrochemical batteries, such as lithium-ion batteries and lithium polymer batteries, generally use aluminum-plastic composite films as packaging materials. A typical aluminum-plastic film structure is usually composed of three layers: the outermost layer is nylon or polyethylene terephthalate (PET) with good weather resistance, mainly providing mechanical protection and puncture resistance; the middle layer is a high-purity aluminum foil, which acts as a barrier layer to effectively prevent the penetration of moisture and oxygen, ensuring the stability of the internal environment of the battery; the innermost layer is a heat-sealing layer, usually using polypropylene (PP) or polyethylene (PE) thermoplastic resin, responsible for reliable sealing with the battery tabs during the packaging process. This multi-layer composite structure meets the basic packaging needs of the battery to some extent.

[0004] However, with the continuous improvement of battery energy density, the increasingly harsh working environment, and the continuous improvement of the requirements for long life and high safety of batteries, the performance bottlenecks of the existing heat-sealing layer packaging materials gradually appear. First, in terms of tensile strength, the existing materials do not perform well. During the manufacturing, transportation, and use of batteries, the packaging material needs to withstand certain mechanical stress, such as winding, stacking, liquid injection, formation, and external impact. The tensile strength of the existing heat-sealing layer materials is generally low, making it difficult to effectively resist deformation and rupture under high stress. During the charging and discharging cycle of the battery, the electrode material will expand and contract in volume, causing periodic stress inside. If the tensile strength of the packaging material is insufficient, micro-cracks may easily occur at the heat-sealing edge or stress concentration area, leading to serious safety problems such as liquid leakage and short circuit.

[0005] Secondly, the aging resistance is another key indicator that needs to be improved. During long-term service, the battery is continuously exposed to complex environments such as high temperature, high humidity, electrolyte corrosion, and electrochemical oxidation. The existing packaging materials, especially the heat-sealing layer resin, are prone to hydrolysis, oxidation and reduction of crosslinking degree under high temperature and high humidity conditions, resulting in material embrittlement and adhesion strength reduction; at the same time, the strong corrosive substances such as HF produced by the decomposition of organic solvents (such as carbonate) and lithium salts (such as LiPF6) in the electrolyte can corrode the aluminum foil layer and the adhesive, destroy the interlayer bonding force, and cause delamination, bulging and other failure modes.

[0006] In summary, developing a new type of electrochemical battery packaging material with high tensile strength, excellent aging resistance and good comprehensive performance has become a key technical problem that needs to be solved in the current battery technology field. This not only has important significance for improving the safety and service life of the battery, but also provides a solid foundation for the widespread application of the next generation of high-performance energy storage systems. SUMMARY

[0007] The purpose of the present application is to provide an electrochemical battery packaging material and a preparation method thereof.

[0008] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: An electrochemical battery packaging material, comprising the following components in mass fraction: styrene block copolymer 20-30 parts, maleic anhydride grafted styrene-ethylene / butylene-styrene 20-30 parts, synergistic resin 20-50 parts, crosslinking agent 1-2 parts, silane coupling agent 1-2 parts, antioxidant 1-2 parts, solvent 300-350 parts.

[0009] Preferably, the preparation method of the synergistic resin comprises the following steps: S1: Take acrylic acid and deionized water, then add ammonium persulfate as an initiator, react under a nitrogen protective atmosphere to obtain a polyacrylic acid product, after the reaction is completed, dilute the product with deionized water to obtain a polyacrylic acid aqueous solution; S2: Take the polyacrylic acid aqueous solution, add sodium hydroxide to adjust the pH value of the reaction system, add 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride as a coupling agent, stir, add dopamine hydrochloride, and continuously stir at room temperature to obtain a dopamine grafted polyacrylic acid solution; S3: Add sodium hydroxide to the dopamine grafted polyacrylic acid solution and continue to stir to obtain a crude product; S4: Add ethanol dropwise to the continuously stirred crude product to induce the precipitation of the polymer; remove the residual ethanol to finally obtain the synergistic resin.

[0010] Preferably, in S1, the reaction is carried out at 45-50°C for 10-15h.

[0011] Preferably, the pH value of the reaction system is adjusted to 4.5-6.5 by sodium hydroxide in S2.

[0012] Preferably, the coupling agent is 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride.

[0013] Preferably, the amount of the synergistic resin is 50-60wt% of the total amount of the styrene block copolymer and the maleic anhydride grafted styrene-ethylene / butylene-styrene.

[0014] Preferably, the antioxidant is Irganox1010.

[0015] Preferably, the silane coupling agent is silane coupling agent KH-550.

[0016] Preferably, the crosslinking agent is dicumyl peroxide DCP.

[0017] The preparation method of the electrochemical cell packaging material comprises the following steps: Step one: in the main reaction kettle, the formula amount of solvent toluene is added, and stirring is started. At room temperature, styrene block copolymer and maleic anhydride grafted styrene-ethylene / butylene-styrene are added, and continuous stirring is carried out until all the polymers are completely dissolved, forming a uniform, clear viscous solution.

[0018] Step two: the synergistic resin is added to the main reaction kettle, and stirring is fully carried out to ensure that the synergistic resin is completely dispersed and dissolved in the polymer solution.

[0019] Step three: the antioxidant, the silane coupling agent and the crosslinking agent are sequentially added to the reaction kettle. Step four: after the addition is completed, continuous stirring is carried out to ensure that the components of the whole system are extremely uniformly mixed, and vacuum degassing treatment is carried out until the glue solution is clear and transparent, and the electrochemical cell packaging material is obtained. Compared with the prior art, the advantages and beneficial effects of the present application are: 1、In the packaging structure of electrochemical cells, the mechanical properties and durability of the material directly determine the safety and service life of the battery. The introduction of synergistic resin plays a key role in improving the comprehensive performance of the packaging material. Traditional packaging materials such as aluminum plastic film have obvious shortcomings in interlayer adhesion strength and environmental aging resistance, especially in high temperature and humidity or long-term cycling conditions, which are prone to delamination, bulging and even leakage. By adding an appropriate amount of synergistic resin to the packaging material, the tensile strength, tear resistance and impact resistance of the material can be effectively improved. At the same time, the functional groups rich in the molecular structure of the synergistic resin can improve the cohesive energy density of the material, inhibit the expansion of micro-cracks, and maintain structural stability under thermal-oxidative, hygrothermal and other aging conditions, thereby significantly extending the service life of the packaging material. It provides a material basis for high-reliability battery packaging.

[0020] 2、The performance optimization of the packaging material not only depends on the improvement of a single component, but also on the synergistic ratio between multiple components. Styrene block copolymer as a material with good flexibility and processing performance; maleic anhydride grafted styrene-ethylene / butylene-styrene enhances the chemical bonding ability with metal aluminum foil and polar polymer through polar anhydride groups to improve adhesion reliability; and synergistic resin further strengthens the interlayer bonding by adjusting the interface polarity and compatibility. The ratio between the three has a decisive influence on the final performance. When the three are within a certain mass ratio range, the material can achieve the optimal balance of tensile strength, aging resistance and adhesion. Proportion imbalance can easily lead to brittle material or insufficient adhesion, which cannot meet the requirements of dimensional stability and sealing in long-term cycling of the battery. Therefore, by accurately controlling the ratio of the three, synergistic optimization from the molecular level to the macroscopic performance can be achieved, and a composite packaging system with high strength, high toughness and high durability is constructed.

[0021] 3、The design concept and technical path of the packaging material of the present application have important practical application value and industrialization prospect. With the increasing requirements of new energy vehicles, energy storage power stations and other battery safety and service life, traditional packaging materials have been difficult to meet the use requirements of high energy density batteries under complex working conditions. By optimizing the compounding ratio of styrene block copolymer, maleic anhydride grafted modifier and synergistic resin, the developed high-performance packaging material not only improves the mechanical reliability and environmental tolerance of the battery, but also reduces the risk of thermal runaway caused by packaging failure, thereby significantly improving the overall safety level of the battery system. From the economic point of view, performance leap can be achieved through formula optimization, which can reduce material thickness or prolong battery maintenance period, thereby reducing the life cycle cost. Therefore, this technology not only promotes the upgrading of key battery materials, but also provides strong support for the large-scale application of the next generation of high-safety, long-life electrochemical energy storage systems. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0023] Styrene block copolymer, Kraton G1650MU, USA.

[0024] Maleic anhydride grafted styrene-ethylene / butylene-styrene, FG1924GT, USA.

[0025] Embodiment 1 The present embodiment provides an electrochemical cell packaging material, which comprises the following components in mass fraction: 23 parts of styrene block copolymer, 27 parts of maleic anhydride grafted styrene-ethylene / butylene-styrene, 25 parts of synergistic resin, 1.3 parts of crosslinking agent, 1.7 parts of silane coupling agent, 1.4 parts of antioxidant, and 320 parts of toluene.

[0026] The preparation method of the synergistic resin comprises the following steps: S1: 150 parts of acrylic acid and 27 parts of deionized water are mixed, and then 0.8 parts of ammonium persulfate is added as an initiator. Under a nitrogen protective atmosphere, the reaction is carried out at 45℃ for 10h to obtain a polyacrylic acid product. After the reaction is completed, the product is diluted with deionized water to adjust to a 10wt% polyacrylic acid aqueous solution, and is ready for use.

[0027] S2: 1000 parts of the above-mentioned 10wt% polyacrylic acid aqueous solution is taken, and 40 parts of sodium hydroxide is added to adjust the pH value of the reaction system to 5.0. Then, 10 parts of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) is added as a coupling agent, and is stirred for 30 minutes to make it fully dissolved and uniformly dispersed. Next, 10 parts of dopamine hydrochloride is added, and the reaction is continuously stirred at room temperature for 24h to make the dopamine molecules successfully grafted onto the polyacrylic acid main chain to obtain a dopamine grafted polyacrylic acid solution; S3: 15 parts of sodium hydroxide is added to the above-mentioned dopamine grafted polyacrylic acid solution to make the reaction system in an alkaline environment. Under this condition, the dopamine side chain undergoes an oxidative self-polymerization reaction to form a crosslinked structure. The stirring reaction is continued for 24h to promote the three-dimensional network crosslinking between molecules through dopamine self-polymerization to obtain a crude product; S4: 500 parts of ethanol is added dropwise to the continuously stirred crude product to induce the polymer to precipitate; heating at 80℃ for 2h removes the residual ethanol, and finally the synergistic resin is obtained.

[0028] The antioxidant is Irganox 1010.

[0029] The silane coupling agent is silane coupling agent KH-550.

[0030] The crosslinking agent is dicumyl peroxide DCP.

[0031] A preparation method of an electrochemical cell packaging material, comprising the following steps: Step one: in the main reaction kettle, add the formula amount of solvent toluene, start stirring, add styrene block copolymer and maleic anhydride grafted modified styrene-ethylene / butylene-styrene at room temperature, continue stirring until all the polymers are completely dissolved, forming a uniform, clear viscous solution.

[0032] Step two: add synergistic resin to the main reaction kettle, stir well to ensure that the synergistic resin is completely dispersed and dissolved in the polymer solution.

[0033] Step three: add antioxidants, silane coupling agents, crosslinking agents to the reaction kettle in turn; Step four: after the feeding is completed, continue stirring for 4h to ensure that the components of the whole system are mixed extremely uniformly, vacuum degassing treatment until the glue solution is clear and transparent, no visible bubbles, electrochemical cell packaging material is obtained.

[0034] Example 2 The present embodiment provides an electrochemical cell packaging material, comprising the following components in mass fraction: styrene block copolymer 20 parts, maleic anhydride grafted modified styrene-ethylene / butylene-styrene 30 parts, synergistic resin 27 parts, crosslinking agent 2 parts, silane coupling agent 1 part, antioxidant 2 parts, toluene 300 parts.

[0035] The preparation method of the synergistic resin comprises the following steps: S1: take 150 parts of acrylic acid and 27 parts of deionized water, then add 0.8 parts of ammonium persulfate as initiator. Under the protection of nitrogen atmosphere, react at 45℃ for 10h to obtain polyacrylic acid product. After the reaction is completed, dilute the product with deionized water to adjust to a 10wt% polyacrylic acid aqueous solution, and reserve.

[0036] S2: take 1000 parts of the above 10wt% polyacrylic acid aqueous solution, add 40 parts of sodium hydroxide to adjust the pH value of the reaction system to 5.0. Then, add 10 parts of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) as a coupling agent, stir for 30 minutes to make it fully dissolved and dispersed uniformly. Then, add 10 parts of dopamine hydrochloride, continue stirring at room temperature for 24h to make dopamine molecules successfully grafted onto the polyacrylic acid backbone to obtain a dopamine grafted polyacrylic acid solution; S3: 15 parts of sodium hydroxide were added to the above dopamine grafted polyacrylic acid solution to make the reaction system in an alkaline environment. Under this condition, the dopamine side chain undergoes oxidative self-polymerization reaction, and then forms a cross-linked structure. Continue to stir for 24 h to promote the three-dimensional network cross-linking between molecules through dopamine self-polymerization to obtain a crude product; S4: 500 parts of ethanol were added dropwise to the continuously stirred crude product to induce the polymer to precipitate; heat at 80°C for 2 h to remove the residual ethanol, and finally obtain the synergistic resin.

[0037] The antioxidant is Irganox 1010.

[0038] The silane coupling agent is silane coupling agent KH-550.

[0039] The crosslinking agent is dicumyl peroxide DCP.

[0040] A preparation method of an electrochemical cell packaging material, comprising the following steps: Step one: in the main reaction kettle, add the formula amount of solvent toluene, start stirring, add styrene block copolymer and maleic anhydride grafted modified styrene-ethylene / butylene-styrene at room temperature, continue stirring until all the polymers are completely dissolved, forming a uniform, clear viscous solution.

[0041] Step two: add the synergistic resin into the main reaction kettle, stir well to ensure that the synergistic resin is completely dispersed and dissolved in the polymer solution.

[0042] Step three: add the antioxidant, silane coupling agent and crosslinking agent into the reaction kettle in turn; Step four: after the addition is completed, continue to stir for 4 h to ensure that the components in the whole system are mixed extremely uniformly, and then vacuum degassing treatment is performed until the glue solution is clear and transparent without visible bubbles, thereby obtaining the electrochemical cell packaging material.

[0043] Comparative example 1 The difference between this comparative example and example 1 is that: an electrochemical cell packaging material comprises the following components in mass fraction: styrene block copolymer 23 parts, maleic anhydride grafted modified styrene-ethylene / butylene-styrene 27 parts, crosslinking agent 1.3 parts, silane coupling agent 1.7 parts, antioxidant 1.4 parts, toluene 320 parts.

[0044] Comparative example 2 The difference between this comparative example and example 1 is that: an electrochemical cell packaging material comprises the following components in mass fraction: styrene block copolymer 23 parts, maleic anhydride grafted modified styrene-ethylene / butylene-styrene 27 parts, synergistic resin 20 parts, crosslinking agent 1.3 parts, silane coupling agent 1.7 parts, antioxidant 1.4 parts, toluene 320 parts.

[0045] Comparative Example 3 The difference between this comparative example and Example 1 is that an electrochemical cell packaging material comprises the following components in mass parts: styrene block copolymer 23 parts, maleic anhydride grafted styrene-ethylene / butylene-styrene 27 parts, synergistic resin 50 parts, crosslinking agent 1.3 parts, silane coupling agent 1.7 parts, antioxidant 1.4 parts, and toluene 320 parts.

[0046] Comparative Example 4 The difference between this comparative example and Example 1 is that an electrochemical cell packaging material comprises the following components in mass parts: styrene block copolymer 35 parts, maleic anhydride grafted styrene-ethylene / butylene-styrene 20 parts, synergistic resin 20 parts, crosslinking agent 1.3 parts, silane coupling agent 1.7 parts, antioxidant 1.4 parts, and toluene 320 parts.

[0047] Comparative Example 5 The difference between this comparative example and Example 1 is that an electrochemical cell packaging material comprises the following components in mass parts: styrene block copolymer 21 parts, maleic anhydride grafted styrene-ethylene / butylene-styrene 37 parts, synergistic resin 20 parts, crosslinking agent 1.3 parts, silane coupling agent 1.7 parts, antioxidant 1.4 parts, and toluene 320 parts.

[0048] Performance test The packaging materials prepared in Examples 1-2 and Comparative Examples 1-5 were subjected to performance tests.

[0049] (1) Tensile strength: tested by a universal electronic testing machine according to GB / T 2567-2021 standard at a tensile rate of 20 mm / min.

[0050] (2) Aging resistance: the sample thickness was 0.2 mm, and the sample was placed in a constant temperature and humidity chamber at a temperature of 65°C and a relative humidity of 80%, and after 6 months of storage, whether there were obvious corrosion damage, yellowing, blistering, cracking, etc. was observed. If there were, it was recorded as unqualified, otherwise it was qualified. Each group was tested 100 times, and the number of qualified samples was counted.

[0051] (3) Copper-clad board adhesion: tested according to GB / T 40564-2021 “Test method for epoxy molding compound for electronic packaging”.

[0052] The results are shown in Table 1.

[0053] Table 1 Performance test results As can be seen from Table 1, the packaging materials prepared in Examples 1-2 have excellent comprehensive performance.

[0054] It can be seen from the comparative example 1 that the addition of the synergistic resin can obviously improve the mechanical properties and aging resistance of the packaging material.

[0055] It can be seen from the comparative examples 2-5 that the ratio relationship among the styrene block copolymer, the maleic anhydride grafted styrene-ethylene / butylene-styrene and the synergistic resin has an important influence on the comprehensive performance of the packaging material, and only when the three are compounded in a specific ratio can the tensile strength, excellent aging resistance and adhesion be balanced, and the performance of the packaging material be synergistically improved.

[0056] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An electrochemical battery encapsulation material, characterized in that, The product comprises the following components in parts by weight: 20-30 parts of styrene block copolymer, 20-30 parts of maleic anhydride grafted modified styrene-ethylene / butene-styrene, 20-50 parts of synergistic resin, 1-2 parts of crosslinking agent, 1-2 parts of silane coupling agent, 1-2 parts of antioxidant, and 300-350 parts of solvent.

2. The electrochemical battery encapsulation material according to claim 1, characterized in that, The preparation method of the synergistic resin includes the following steps: S1: Acrylic acid and deionized water are mixed, and then ammonium persulfate is added as an initiator. The reaction is carried out under a nitrogen protective atmosphere to obtain polyacrylic acid product. After the reaction is completed, the product is diluted with deionized water to obtain polyacrylic acid aqueous solution. S2: Take an aqueous solution of polyacrylic acid, add sodium hydroxide to adjust the pH of the reaction system, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride as a coupling agent, stir, add dopamine hydrochloride, and continue stirring the reaction at room temperature to obtain a dopamine-grafted polyacrylic acid solution. S3: Add sodium hydroxide to the above dopamine-grafted polyacrylic acid solution and continue stirring to obtain the crude product; S4: Add ethanol dropwise to the crude product under continuous stirring to induce the polymer to precipitate; remove residual ethanol to finally obtain the enhanced resin.

3. The electrochemical battery encapsulation material according to claim 2, characterized in that, The reaction in S1 is carried out at 45-50℃ for 10-15 hours.

4. The electrochemical battery encapsulation material according to claim 2, characterized in that, Sodium hydroxide is added to S2 to adjust the pH of the reaction system to 4.5-6.

5.

5. The electrochemical battery encapsulation material according to claim 2, characterized in that, The coupling agent is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

6. The electrochemical battery encapsulation material according to claim 2, characterized in that, The amount of the synergistic resin is 50-60 wt% of the total amount of styrene block copolymer and maleic anhydride graft-modified styrene-ethylene / butene-styrene.

7. The electrochemical battery encapsulation material according to claim 1, characterized in that, The antioxidant is Irganox 1010.

8. The electrochemical battery encapsulation material according to claim 1, characterized in that, The silane coupling agent is silane coupling agent KH-550.

9. The electrochemical battery encapsulation material according to claim 1, characterized in that, The crosslinking agent is dicumyl peroxide (DCP).

10. A method for preparing an electrochemical battery encapsulation material according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: In the main reactor, add the prescribed amount of solvent toluene, start stirring, and at room temperature, add styrene block copolymer and maleic anhydride grafted modified styrene-ethylene / butene-styrene, and continue stirring until all polymers are completely dissolved to form a homogeneous, clear, viscous solution. Step 2: Add the synergistic resin to the main reactor and stir thoroughly to ensure that the synergistic resin is completely dispersed and dissolved in the polymer solution; Step 3: Add antioxidant, silane coupling agent, and crosslinking agent to the reactor in sequence; Step 4: After the material is added, continue stirring until it is evenly mixed, and then perform vacuum degassing to obtain the electrochemical battery encapsulation material.

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