A power battery insulating pressure-sensitive adhesive and a preparation method thereof

Abstract

The application discloses a power battery insulating pressure-sensitive adhesive and a preparation method thereof, and belongs to the technical field of high polymer materials, which comprises an insulating base material, a fluorine grafting agent, a phosphorus grafting agent, a silicon-based resin, a cross-linking agent and a platinum gold catalyst, and the preparation method comprises the following steps: S1, fluorine side-linking grafting; S2, phosphorus side-linking grafting; S3, silicon-based resin dispersion; S4, cross-linking reaction; and S5, impurity removal and purification. Through fluorine-phosphorus side-linking grafting reaction, the balance between initial adhesion and adhesion retention of the system is optimized, and a synergistic protection system is constructed. The fluorine element forms a dense penetration barrier, and the phosphorus element provides efficient carbonization and flame-retardant sites. In combination with the insulating skeleton of PHMS and the cross-linking network of PHS, the problems of insufficient insulating stability, imbalance between initial adhesion and adhesion retention and poor flame retardancy caused by lack of targeted functional modification in the prior art are solved, and the application has the potential to be applied to the preparation of power battery pressure-sensitive adhesive.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a power battery insulating pressure-sensitive adhesive and its preparation method. Background Technology

[0002] With the rapid rise of new energy vehicles and energy storage industries, power batteries are continuously iterating towards higher energy density, longer cycle life, and higher safety. As a key core component for power battery power transmission and structural connection, the tabs' insulation and protection performance directly determines the battery's operational stability and safety boundaries, placing stringent multi-dimensional requirements on the comprehensive performance of insulating pressure-sensitive adhesives. In power battery scenarios, traditional insulating pressure-sensitive adhesives suffer from multiple defects, including unstable insulation leading to tab leakage, imbalance between initial tack and holding tack resulting in poor adhesion and long-term slippage, swelling and aging under electrolyte erosion leading to loss of protective function, and insufficient flame retardancy exacerbating the risk of thermal runaway. These problems, when combined, not only shorten the service life of power batteries and significantly increase maintenance costs, but also potentially cause safety accidents, severely restricting the application expansion of power batteries in high-end new energy equipment.

[0003] Therefore, there is an urgent need for a new type of multifunctional synergistic modified power battery insulating pressure-sensitive adhesive system to achieve an integrated improvement in insulation stability, flame retardancy, electrolyte aging resistance and adhesion performance, solve the technical bottleneck of functional fragmentation and performance imbalance in traditional products, and provide long-term and reliable insulation protection for power batteries. Summary of the Invention

[0004] Therefore, the present invention provides a power battery insulating pressure-sensitive adhesive and its preparation method to solve the problems of insufficient insulation stability, poor adhesion, imbalance between initial tack and holding tack, and poor flame retardancy caused by the lack of targeted functional modification in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] According to a first aspect of the present invention, a power battery insulating pressure-sensitive adhesive is provided, comprising an insulating base material, a fluorine grafting agent, a phosphorus grafting agent, a silicone resin, a crosslinking agent, a platinum catalyst, and a side reaction inhibitor.

[0007] Furthermore, the mass ratio of each component is as follows: 90-110 parts of insulating base material, 10-20 parts of fluorine grafting agent, 3-6 parts of phosphorus grafting agent, 5-30 parts of silicone resin, 1-10 parts of crosslinking agent, 0.1-0.5 parts of platinum catalyst, and 0.01-0.05 parts of side reaction inhibitor.

[0008] Furthermore, the mass ratio of each component is as follows: 100 parts of insulating base material, 20 parts of fluorine grafting agent, 6 parts of phosphorus grafting agent, 16.7 parts of silicone resin, 5 parts of crosslinking agent, 0.2 parts of platinum catalyst, and 0.04 parts of side reaction inhibitor.

[0009] Furthermore, the insulating base material is hydrogen-containing polydimethylsiloxane with a hydrogen content of 0.5%, the fluorine grafting agent is 3,3,3-trifluoropropyltrimethoxysilane, the phosphorus grafting agent is diphenylphosphinoethyldimethoxysilane, the silicone resin is vinyl MQ silicone resin, the crosslinking agent is phenyl hydrogen-containing silicone oil, the platinum catalyst is Karstedt catalyst, and the side reaction inhibitor is ethynylcyclohexanol.

[0010] According to a second aspect of the present invention, a method for preparing a power battery insulating pressure-sensitive adhesive is provided, comprising the following steps:

[0011] S1, fluoride lateral branches;

[0012] S2, phosphorus lateral linking branch;

[0013] S3, silicone resin dispersion;

[0014] S4, cross-linking reaction;

[0015] S5. Purification and Impurity Removal:

[0016] a. Transfer the product from step S4 to a single-necked flask and evaporate it at 120°C under reduced pressure of -0.1 MPa for 4 hours until no toluene distills off;

[0017] b. Place the devolatilized product into a Soxhlet extractor and extract with petroleum ether at 60-90℃ for 2 hours to remove unreacted fluorine grafting agent and phosphorus grafting agent monomers.

[0018] c. Add deionized water, stir at room temperature for 30 min to hydrolyze the residual fluoride grafting agent, separate the aqueous phase, dry at 80℃ and -0.05MPa reduced pressure for 2 h to obtain purified gel solution;

[0019] S6. Spin coat the purified adhesive onto the fluorine-modified PI film, place it in an oven at 80°C for 3 hours, and cure at room temperature for 24 hours to obtain the power battery insulating pressure-sensitive adhesive.

[0020] Further, step S1 includes the following steps:

[0021] a. Mix the insulating base material with anhydrous toluene at a mass ratio of 1:2-1:2.5, introduce nitrogen gas at a rate of 50-60 mL / min, and magnetically stir at 300 rpm at 60 °C to obtain an insulating base material solution;

[0022] b. Add fluorine grafting agent dropwise to the insulating base material solution at a rate of 5 g / h;

[0023] c. After the addition is complete, add the platinum catalyst, heat to 65°C, and react at a constant temperature for 3.5 hours.

[0024] Further, step S2 includes the following steps:

[0025] a. Add the phosphorus grafting agent while maintaining the system temperature at 65℃, stirring speed at 300rpm, and under nitrogen atmosphere protection;

[0026] b. Add platinum catalyst and continue the reaction at a constant temperature for 3 hours to obtain fluorine-phosphorus modified base material.

[0027] Furthermore, step S3 includes the following steps:

[0028] a. Dissolve silicone resin in toluene at a mass ratio of silicone resin to toluene of 5:3 to obtain a silicone resin solution;

[0029] b. Add silicone resin solution to fluorine-phosphorus modified base material, stir at 65℃ and 300rpm, and disperse at a constant temperature for 1-1.5h to obtain base material-resin.

[0030] Further, step S4 includes the following steps:

[0031] Add crosslinking agent, platinum catalyst and side reaction inhibitor to base resin, heat to 80℃, and crosslink at a constant temperature for 2.5h to obtain pre-pressure sensitive adhesive.

[0032] According to a third aspect of the present invention, an application of a power battery insulating pressure-sensitive adhesive in the preparation of a power battery is provided.

[0033] The present invention has the following advantages:

[0034] 1. Excellent and stable insulation performance: Using hydrogen-containing polydimethylsiloxane (PHMS) as the insulating matrix, a robust insulating skeleton is provided. Combined with the synergistic cross-linking effect of PHS (phenyl hydrogen-containing silicone oil), a dense cross-linked network is formed, resulting in a product volume resistivity ≥10 Ω·cm. 17 With a strength of Ω·cm and a breakdown strength of ≥30kV / mm, it can ensure the long-term insulation reliability of the power battery.

[0035] 2. Precise balance of adhesion performance: The good compatibility between vinyl MQ silicone resin and the base material significantly improves the tack of the system; at the same time, the grafting reaction of 3,3,3-trifluoropropyltrimethoxysilane (TFPTMS) optimizes the initial tack, successfully achieving a synergistic balance between initial tack and tack, resulting in a firm bond that does not slip over a long period of time.

[0036] 3. Excellent resistance to electrolyte aging: The fluorine-phosphorus dual protection design, which uses TFPTMS grafted with fluorine and diphenylphosphine ethyl dimethoxysilane (DPES) grafted with phosphorus, effectively blocks electrolyte penetration and meets the requirements of long-term use.

[0037] 4. Flame retardant performance meets standards: The synergistic flame retardant effect of fluorine and phosphorus elements ensures that the product's oxygen index is ≥30%, which meets industry standards and effectively reduces the risk of fire during the use of power batteries.

[0038] 5. Scientific and reasonable formulation design: Each component has a clear function and synergistic effect. PHMS provides an insulating framework and reaction sites, TFPTMS / DPES realizes functional modification, vinyl MQ silicone resin balances adhesion performance, PHS optimizes the crosslinking structure, Karstedt catalyst precisely controls reaction efficiency, and ethynylcyclohexanol effectively inhibits side reactions. The overall process is mature and controllable, and the product has high stability.

[0039] 6. Suitable for power battery scenarios: The product meets the standards in core indicators such as insulation, adhesion, electrolyte resistance, and flame retardancy. It can be directly applied to the insulation protection of key parts such as the tabs of power batteries and has the potential for application in the manufacture of power batteries. Attached Figure Description

[0040] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0041] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0042] Figure 1 The initial tack diagram of the power battery insulating pressure-sensitive adhesive provided by the present invention;

[0043] Figure 2 The room temperature holding power diagram of the power battery insulating pressure-sensitive adhesive provided by the present invention;

[0044] Figure 3 The holding power diagram at 80°C of the power battery insulating pressure-sensitive adhesive provided by the present invention;

[0045] Figure 4 Peel force diagram of the insulating pressure-sensitive adhesive for power batteries provided by the present invention;

[0046] Figure 5 Electrolyte swelling rate diagram of the power battery insulating pressure-sensitive adhesive provided by the present invention;

[0047] Figure 6 The breakdown voltage diagram of the power battery insulating varistor provided by the present invention;

[0048] Figure 7 The limiting oxygen index diagram of the power battery insulating pressure-sensitive adhesive provided by the present invention. Detailed Implementation

[0049] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] According to a first aspect of the present invention, a power battery insulating pressure-sensitive adhesive is provided, comprising an insulating base material, a fluorine grafting agent, a phosphorus grafting agent, a silicone resin, a crosslinking agent, a platinum catalyst, and a side reaction inhibitor.

[0051] The mass ratio of each component is as follows: 90-110 parts of insulating base material, 10-20 parts of fluorine grafting agent, 3-6 parts of phosphorus grafting agent, 5-30 parts of silicone resin, 1-10 parts of crosslinking agent, 0.1-0.5 parts of platinum catalyst, and 0.01-0.05 parts of side reaction inhibitor.

[0052] The mass ratio of each component is as follows: 100 parts of insulating base material, 20 parts of fluorine grafting agent, 6 parts of phosphorus grafting agent, 16.7 parts of silicone resin, 5 parts of crosslinking agent, 0.2 parts of platinum catalyst, and 0.04 parts of side reaction inhibitor.

[0053] The insulating base material is hydrogen-containing polydimethylsiloxane with a hydrogen content of 0.5%, the fluorine grafting agent is 3,3,3-trifluoropropyltrimethoxysilane, the phosphorus grafting agent is diphenylphosphinoethyldimethoxysilane, the silicone resin is vinyl MQ silicone resin, the crosslinking agent is phenyl hydrogen-containing silicone oil, the platinum catalyst is Karstedt catalyst, and the side reaction inhibitor is ethynylcyclohexanol.

[0054] According to a second aspect of the present invention, a method for preparing a power battery insulating pressure-sensitive adhesive is provided, comprising the following steps:

[0055] S1, fluoride lateral branches;

[0056] S2, phosphorus lateral linking branch;

[0057] S3, silicone resin dispersion;

[0058] S4, cross-linking reaction;

[0059] S5. Purification and Impurity Removal:

[0060] a. Transfer the product from step S4 to a single-necked flask and evaporate it at 120°C under reduced pressure of -0.1 MPa for 4 hours until no toluene distills off;

[0061] b. Place the devolatilized product into a Soxhlet extractor and extract with petroleum ether at 60-90℃ for 2 hours to remove unreacted fluorine grafting agent and phosphorus grafting agent monomers.

[0062] c. Add deionized water, stir at room temperature for 30 min to hydrolyze the residual fluoride grafting agent, separate the aqueous phase, dry at 80℃ and -0.05MPa reduced pressure for 2 h to obtain purified gel solution;

[0063] S6. Spin coat the purified adhesive onto the fluorine-modified PI film, place it in an oven at 80°C for 3 hours, and cure at room temperature for 24 hours to obtain the power battery insulating pressure-sensitive adhesive.

[0064] Step S1 includes the following steps:

[0065] a. Mix the insulating base material with anhydrous toluene at a mass ratio of 1:2-1:2.5, introduce nitrogen gas at a rate of 50-60 mL / min, and magnetically stir at 300 rpm at 60 °C to obtain an insulating base material solution;

[0066] b. Add fluorine grafting agent dropwise to the insulating base material solution at a rate of 5 g / h;

[0067] c. After the addition is complete, add the platinum catalyst, heat to 65°C, and react at a constant temperature for 3.5 hours.

[0068] Further, step S2 includes the following steps:

[0069] a. Add the phosphorus grafting agent while maintaining the system temperature at 65℃, stirring speed at 300rpm, and under nitrogen atmosphere protection;

[0070] b. Add platinum catalyst and continue the reaction at a constant temperature for 3 hours to obtain fluorine-phosphorus modified base material.

[0071] Step S3 includes the following steps:

[0072] a. Dissolve silicone resin in toluene at a mass ratio of silicone resin to toluene of 5:3 to obtain a silicone resin solution;

[0073] b. Add silicone resin solution to fluorine-phosphorus modified base material, stir at 65℃ and 300rpm, and disperse at a constant temperature for 1-1.5h to obtain base material-resin.

[0074] Step S4 includes the following steps:

[0075] Add crosslinking agent, platinum catalyst and side reaction inhibitor to base resin, heat to 80℃, and crosslink at a constant temperature for 2.5h to obtain pre-pressure sensitive adhesive.

[0076] The usage process of this invention embodiment is as follows:

[0077] Example 1

[0078] This embodiment includes the following steps:

[0079] S1, Fluorine lateral grafts:

[0080] a. Mix 100g of hydrogen-containing polydimethylsiloxane with 240g of anhydrous toluene, introduce nitrogen gas at a rate of 50mL / min, and magnetically stir at 300rpm at 60℃ to obtain an insulating base material solution.

[0081] b. Add 20g of TFPTMS dropwise to the insulating base solution at a rate of 5g / h;

[0082] c. After the dropwise addition is complete, add 0.1g of Karstedt catalyst in two portions, 0.05g each time, to control the catalyst concentration at each addition in order to suppress side reactions and ensure a stable reaction system. Heat the system to 65℃ and keep it at that temperature for 3.5h.

[0083] S2, phosphorus lateral linker:

[0084] a. Add 6g of DPES while maintaining the system temperature at 65℃, stirring speed at 300rpm, and under nitrogen atmosphere protection;

[0085] b. Add 0.05g of Karstedt catalyst and continue the reaction at a constant temperature for 3h to obtain fluorine-phosphorus modified base material;

[0086] S3, Silicone-based resin dispersion:

[0087] a. Dissolve 16.7g of vinyl MQ silicone resin in 10g of toluene to obtain a silicone resin solution;

[0088] b. Add silicone resin solution to fluorine-phosphorus modified base material, stir at 65℃ and 300rpm, and disperse at a constant temperature for 1h to obtain base material-resin;

[0089] S4, Crosslinking reaction:

[0090] Add 5g of phenyl hydrogen silicone oil (PHS), 0.05g of Karstedt catalyst and 0.04g of ethynylcyclohexanol to the base material-resin, heat to 80℃, and crosslink at a constant temperature for 2.5h to obtain a pre-pressure sensitive adhesive.

[0091] S5. Purification and Impurity Removal:

[0092] a. Transfer the pre-pressurized adhesive to a single-necked flask and volatilize at 120°C under reduced pressure of -0.1 MPa for 4 hours until no toluene distills off;

[0093] b. Place the devolatilized product into a Soxhlet extractor and extract with 100g of petroleum ether at 60-90℃ for 2h to remove unreacted TFPTMS and DPES monomers;

[0094] c. Add 20 mL of deionized water, stir at room temperature for 30 min to hydrolyze the residual TFPTMS, separate the aqueous phase, and dry at 80 °C under reduced pressure of -0.05 MPa for 2 h to obtain the purified gel solution.

[0095] S6. Spin coat the purified adhesive onto the fluorine-modified PI film, place it in an oven at 80°C for 3 hours, and cure at room temperature for 24 hours to obtain the power battery insulating pressure-sensitive adhesive, thus obtaining pressure-sensitive adhesive 1.

[0096] Example 2

[0097] The formulation ratio of this embodiment is based on that of Example 1. The difference is in step S3a, where the amount of vinyl MQ resin added is 30g of resin dissolved in 20g of toluene. The specific processing parameters are the same as those in Example 1, resulting in pressure-sensitive adhesive 2.

[0098] Example 3

[0099] The formulation ratio of this embodiment is based on that of Example 1. The difference is that the amount of TFPTMS added in step S1, b is 10g, and the amount of DPES added in step S2, a is 3g. The specific processing parameters are the same as those in Example 1, and pressure-sensitive adhesive 3 is prepared.

[0100] Comparative Example 1

[0101] The formulation of this comparative example is based on Example 1, except that TFPTMS and Karstedt catalyst are not added in step S1, b, and DPES and Karstedt catalyst are not added in step S2, a, i.e., fluorine side-linking and phosphorus side-linking are not performed. The specific processing parameters are the same as in Example 1, and pressure-sensitive adhesive D1 is prepared.

[0102] Comparative Example 2

[0103] The formulation of this comparative example is based on that of Example 1, except that vinyl MQ resin is not added in step S3. The specific processing parameters are the same as those of Example 1, and pressure-sensitive adhesive D2 is prepared.

[0104] Comparative Example 3

[0105] The formulation of this comparative example is based on Example 1, except that phenyl hydrogen silicone oil, Karstedt catalyst and ethynylcyclohexanol are not added in step S4, that is, the crosslinking reaction in step S4 is not carried out. The specific processing parameters are the same as in Example 1, and pressure-sensitive adhesive D3 is prepared.

[0106] Comparative Example 4

[0107] The formulation of this comparative example is based on that of Example 1, except that no insulating base solution is added in step S1. The specific processing parameters are the same as those in Example 1, and pressure-sensitive adhesive D4 is prepared.

[0108] Test Example 1

[0109] The pressure-sensitive adhesive for power battery insulation was tested according to GB / T 4852-2002 (Method A: inclined plane rolling ball method) for initial tack, GB / T 2792-1998 for 180° peel force, and GB / T 4851-1998 for holding power.

[0110] Figure 1 , Figure 2 , Figure 3 and Figure 4The figures show the initial tack, holding power at room temperature, holding power at 80°C, and peel force of the power battery insulating pressure-sensitive adhesive provided by this invention. It can be seen that Example 1 exhibits good initial tack-holding power balance, with initial tack, holding power at room temperature, holding power at 80°C, and peel force at 180°C for a 26# steel ball, 250h, 122.5h, and 1.9N / 25mm, respectively. In Example 2, increasing the amount of vinyl MQ resin to 30g increased the holding power of the insulating pressure-sensitive adhesive to 310h at room temperature and 155h at 80°C, but the initial tack and peel force decreased to a 20# steel ball and 1.3N / 25mm, respectively. In contrast, the absence of vinyl MQ resin in pressure-sensitive adhesive D2 resulted in increased initial tack and peel force but decreased holding power. This indicates that MQ resin is crucial for providing holding power to the insulating pressure-sensitive adhesive, while excessive amounts inhibit initial tack and disrupt the adhesion balance. Samples PSA 3 and PSA D1 were prepared with reduced TFPTMS and DPES additions of 10g and 3g respectively, and without fluorine and phosphorus side grafting respectively. Compared with PSA 1, the initial tack, room temperature holding tack, 80℃ holding tack, and 180° peel strength of PSA 3 and PSA D1 decreased by 13.5% and 42.3%, 16.0% and 34.0%, 14.3% and 30.6%, and 39.5% and 63.2% respectively. This indicates that fluorine grafting directly contributes to the improvement of initial tack. PSA D3 and PSA D4 did not contain phenyl hydrogen silicone oil and PHMS, respectively. The holding power of PSA D3 decreased significantly, indicating that phenyl hydrogen silicone oil promotes the cross-linking network of the PSA and stabilizes the adhesive layer structure. The initial tack and room temperature holding power of PSA D4 decreased by 42.3% and 56.0% respectively compared with PSA D1, indicating that the absence of PHMS as the basic skeleton of the adhesive layer led to unstable adhesive layer morphology, structural collapse, and thus caused a comprehensive deterioration of adhesion performance.

[0111] Test Example 2

[0112] Electrolyte resistance verification

[0113] S1. Preparation of electrolyte for power batteries:

[0114] Mix 100 mL of ethylene carbonate, 100 mL of dimethyl carbonate and 100 mL of ethyl methyl carbonate, add 45.57 g of LiPF6, stir well, seal and let stand for 24 h to remove air bubbles to obtain the power battery electrolyte.

[0115] S2. Sample immersion treatment:

[0116] a. Sampling:

[0117] Cut five 50mm×50mm samples, accurately measure and record the initial mass (m0) of each sample.

[0118] b. Soaking procedure:

[0119] Immerse the sample completely in a sealed electrolyte container, ensuring that the sample does not overlap or contact the container wall. Place the container in an 85°C constant temperature oven and let it stand for 7 days.

[0120] c. Post-processing:

[0121] After soaking, remove the sample with tweezers, quickly wash the surface of the sample with anhydrous ethanol to remove residual electrolyte, and let it air dry for 30 minutes.

[0122] S3, Swelling Rate Test:

[0123] Accurately measure the mass (m1) of the sample after soaking, and the electrolyte swelling rate (Q) of the power battery insulating pressure-sensitive adhesive. m ) through formula calculate.

[0124] Figure 5 The diagram shows the electrolyte swelling rate of the power battery insulating pressure-sensitive adhesive provided by this invention. The electrolyte swelling rates of Examples 1-3 and Comparative Examples 1-4 are 0.29%, 0.2%, 0.45%, 1.1%, 0.32%, 0.7%, and 0.7%, respectively. It can be seen that increasing the amount of vinyl MQ resin reduces the electrolyte swelling rate of the pressure-sensitive adhesive. Essentially, the vinyl MQ resin plays an auxiliary role by optimizing the adhesive layer structure. On one hand, the vinyl MQ resin is uniformly dispersed and synergistically crosslinked with PHS, improving the density of the adhesive layer and reducing electrolyte penetration channels. On the other hand, it enhances the cohesive strength and structural stability of the adhesive layer, inhibiting swelling deformation. However, the core of the pressure-sensitive adhesive's electrolyte resistance performance is still determined by the fluorine-phosphorus dual protection system constructed from TFPTMS and DPES. The MQ resin does not directly participate in electrolyte barrier; it only further reduces the swelling rate through structural optimization under the premise of complete core protection.

[0125] Test Example 3

[0126] S1, Volume Resistivity Test

[0127] a. Sampling: Cut five 100mm×100mm samples from the cured tape, ensuring that the sample surface is free of bubbles, impurities, wrinkles, and that the adhesive layer is intact and undamaged.

[0128] b. Sample pretreatment: Place the sample in a standard environment of 25℃ and 50% humidity for 24 hours to equilibrate and eliminate the influence of environmental factors on the test.

[0129] c. Test procedure: Place the sample flat on the measuring electrode, ensuring that the sample and the electrode are completely in contact without gaps; apply a 500V DC voltage, let it stand for 1 minute, and then read the resistance value and record the data.

[0130] d. Calculation and Judgment: Based on the formula ( (where R is the volume resistivity, S is the measuring resistance, S is the measuring electrode area, and d is the adhesive layer thickness) Calculate the volume resistivity of each sample and take the average of 5 samples.

[0131] S2, Breakdown Strength Test

[0132] Sampling: Cut five 50mm × 50mm samples and fix them between the electrodes, ensuring the electrodes are aligned with the center of the sample. Increase the voltage uniformly at a rate of 1kV / s until the sample breaks down, and record the breakdown voltage value. Test three different points on each sample and take the average value. The breakdown strength is calculated using the formula... ( The breakdown strength is calculated as follows: U is the breakdown voltage, and d is the adhesive layer thickness.

[0133] Figure 6 The breakdown voltage diagram of the power battery insulating varistor provided by the present invention; the volume resistivity of the power battery insulating varistor is shown in Table 1.

[0134] Table 1. Volume resistivity of insulating pressure-sensitive adhesive for power batteries

[0135]

[0136] It can be seen that after adding an excessive amount of vinyl MQ resin, the volume resistivity of the insulating varistor decreased from 2×10⁻⁶. 17 The Ω·cm decreased significantly to 5.05×10 15 The volume resistivity of the pressure-sensitive adhesive without MQ resin was 6.01 × 10⁻⁶ Ω·cm, while the volume resistivity of the adhesive without MQ resin was only reduced to 6.01 × 10⁻⁶ Ω·cm. 16 The difference in Ω·cm is due to the fact that PHS crosslinking agent, MQ resin, and PHMS form a dense, continuous, non-porous, interface-free crosslinked network. Charge can only migrate within this continuous silicon-based network, which helps to increase the charge migration resistance of the pressure-sensitive adhesive. Without the addition of MQ resin, the charge migration path remains continuous, but the migration resistance decreases slightly due to the increased gap size, indicating that MQ resin is a reinforcing agent rather than the core of system continuity. When excessive MQ resin is added, it cannot be uniformly dispersed in PHMS, resulting in agglomeration and phase separation, forming a continuous PHMS phase and a dispersed MQ resin agglomerated particles, thus disrupting the system's continuity. Charge can then migrate rapidly through the gaps between MQ particles, drastically reducing the migration resistance. Regarding breakdown voltage, excessive MQ resin agglomeration forms rounded particle interfaces without sharp edges or pores, preventing the electric field from concentrating at the interface and instead helping to disperse the electric field, resulting in a breakdown voltage slightly higher than that of the pressure-sensitive adhesive. In contrast, the crosslinked network of the pressure-sensitive adhesive without MQ resin has tiny pores, causing the electric field to concentrate highly at the pore edges, forming a localized strong electric field that easily triggers electrical breakdown, thus significantly reducing the breakdown voltage.

[0137] Insufficient fluorine-phosphorus grafted side chains and the absence of fluorine-phosphorus grafted side chains in pressure-sensitive adhesives 3 and D1 result in a loose cross-linking network, decreased charge migration resistance, increased system porosity, and electric field concentration, leading to a significant decrease in the insulation performance of the pressure-sensitive adhesives. The absence of phenyl hydrogen-containing silicone oil prevents the system from cross-linking, hindering the formation of an effective cross-linking network structure. The free slippage of molecular chains creates numerous macroscopic pores, resulting in no significant resistance to charge migration and strong electric field concentration due to the dense pores. Conversely, the absence of PHMS base material results in a system without a continuous structure, consisting only of loose particles. Charge migration is unimpeded, and the electric field directly breaks down the loose system. The absence of both components completely renders the insulating effect of the pressure-sensitive adhesives ineffective.

[0138] Test Example 4

[0139] Flame retardancy is tested by the limiting index oxygen test method, specifically referring to GB / T 2406-2025.

[0140] Figure 7 The limiting oxygen index (LOI) diagram of the power battery insulating pressure-sensitive adhesive provided by this invention shows that the LIOIs of Examples 1, 3, and Comparative Example 1 are 33%, 28.5%, and 24.5, respectively. This indicates that DPES provides char formation sites, and TFPTMS assists in stabilizing the char layer. Insufficient or absent DPES results in incomplete char layer formation and a decrease in the OXI. Compared to pressure-sensitive adhesive 1, the LIOIs of pressure-sensitive adhesives D3 and D4 decreased by 10.6% and 30.3%, respectively. This indicates that the lack of a crosslinking agent leads to an extremely loose system, but the fluorine-phosphorus side chains have been successfully grafted onto the PHMS main chain. DPES can still provide char formation sites; the only reason for the decrease in OXI is the uneven distribution of the char layer due to the loose system, but without significant failure. PHMS is the grafting carrier for the fluorine-phosphorus side chains; without a base material, DPES cannot be anchored to the molecular chain, and the core basis for char formation and flame retardancy is lost. With all components loosely mixed, no effective char layer is formed at high temperatures, resulting in a significant decrease in flame retardant performance. Furthermore, the absence or excessive addition of vinyl MQ resin has no significant effect on the flame retardant properties of the pressure-sensitive adhesive, indicating that MQ resin does not directly participate in the flame retardant reaction, but only affects the density of the system.

[0141] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A power battery insulating pressure-sensitive adhesive, characterized in that, It includes insulating base material, fluorine grafting agent, phosphorus grafting agent, silicone resin, crosslinking agent, platinum catalyst and side reaction inhibitor; The insulating base material is hydrogen-containing polydimethylsiloxane with a hydrogen content of 0.5%, the fluorine grafting agent is 3,3,3-trifluoropropyltrimethoxysilane, the phosphorus grafting agent is diphenylphosphinoethyldimethoxysilane, the silicone resin is vinyl MQ silicone resin, the crosslinking agent is phenyl hydrogen-containing silicone oil, the platinum catalyst is Karstedt catalyst, and the side reaction inhibitor is ethynylcyclohexanol. The insulating base material, fluorine grafting agent, phosphorus grafting agent, and platinum catalyst are reacted through the following steps to obtain the fluorine-phosphorus modified base material: S1, Fluorine lateral grafts: a. Mix the insulating base material with anhydrous toluene at a mass ratio of 1:2-1:2.5, introduce nitrogen gas at a rate of 50-60 mL / min, and magnetically stir at 300 rpm at 60 °C to obtain an insulating base material solution; b. Add fluorine grafting agent dropwise to the insulating base material solution at a rate of 5 g / h; c. After the addition is complete, add the platinum catalyst, heat to 65°C, and react at a constant temperature for 3.5 hours; S2, phosphorus lateral linker: a. Add the phosphorus grafting agent while maintaining the system temperature at 65℃, stirring speed at 300rpm, and under nitrogen atmosphere protection; b. Add platinum catalyst and continue the reaction at a constant temperature for 3 hours to obtain fluorine-phosphorus modified base material.

2. The power battery insulating pressure-sensitive adhesive as described in claim 1, characterized in that, The mass ratio of each component is as follows: 90-110 parts of insulating base material, 10-20 parts of fluorine grafting agent, 3-6 parts of phosphorus grafting agent, 5-30 parts of silicone resin, 1-10 parts of crosslinking agent, 0.1-0.5 parts of platinum catalyst, and 0.01-0.05 parts of side reaction inhibitor.

3. The power battery insulating pressure-sensitive adhesive as described in claim 2, characterized in that, The mass ratio of each component is as follows: 100 parts of insulating base material, 20 parts of fluorine grafting agent, 6 parts of phosphorus grafting agent, 16.7 parts of silicone resin, 5 parts of crosslinking agent, 0.2 parts of platinum catalyst, and 0.04 parts of side reaction inhibitor.

4. A method for preparing a power battery insulating pressure-sensitive adhesive, characterized in that, Includes the following steps: S1, Fluorine lateral grafts: a. Mix the insulating base material with anhydrous toluene at a mass ratio of 1:2-1:2.5, introduce nitrogen gas at a rate of 50-60 mL / min, and magnetically stir at 300 rpm at 60°C to obtain an insulating base material solution; wherein, the insulating base material is a hydrogen-containing polydimethylsiloxane with a hydrogen content of 0.5%; b. Add a fluorinated grafting agent dropwise to the insulating base material solution at a rate of 5 g / h; wherein the fluorinated grafting agent is 3,3,3-trifluoropropyltrimethoxysilane; c. After the addition is complete, add a platinum catalyst, heat to 65°C, and react at a constant temperature for 3.5 hours; wherein the platinum catalyst is a Karstedt catalyst. S2, phosphorus lateral linker: a. Add the phosphorus grafting agent while maintaining the system temperature at 65℃, stirring speed at 300 rpm, and under nitrogen atmosphere protection; wherein, the phosphorus grafting agent is diphenylphosphinoethyldimethoxysilane; b. Add a platinum catalyst and continue the reaction at a constant temperature for 3 hours to obtain a fluorine-phosphorus modified base material; wherein, the platinum catalyst is a Karstedt catalyst; S3, Silicone-based resin dispersion: a. Dissolve a silicone resin in toluene at a mass ratio of 5:3 to obtain a silicone resin solution; wherein the silicone resin is vinyl MQ silicone resin; b. Add silicone resin solution to fluorine-phosphorus modified base material, stir at 65℃ and 300rpm, and disperse at a constant temperature for 1-1.5h to obtain base material-resin; S4, cross-linking reaction; S5. Purification and Impurity Removal: a. Transfer the product from step S4 to a single-necked flask and evaporate it at 120°C under reduced pressure of -0.1 MPa for 4 hours until no toluene distills off; b. Place the devolatilized product into a Soxhlet extractor and extract with petroleum ether at 60-90℃ for 2 hours to remove unreacted fluorine grafting agent and phosphorus grafting agent monomers. c. Add deionized water, stir at room temperature for 30 min to hydrolyze the residual fluoride grafting agent, separate the aqueous phase, dry at 80℃ and -0.05MPa reduced pressure for 2 h to obtain purified gel solution; S6. Spin coat the purified adhesive onto the fluorine-modified PI film, place it in an oven at 80°C for 3 hours, and cure at room temperature for 24 hours to obtain the power battery insulating pressure-sensitive adhesive.

5. The method for preparing the power battery insulating pressure-sensitive adhesive as described in claim 4, characterized in that, Step S4 includes the following steps: A crosslinking agent, a platinum catalyst, and a side reaction inhibitor are added to the base material-resin, the temperature is raised to 80°C, and crosslinking is carried out at a constant temperature for 2.5 hours to obtain a pre-pressure sensitive adhesive; wherein the crosslinking agent is phenyl hydrogen silicone oil, the platinum catalyst is Karstedt catalyst, and the side reaction inhibitor is ethynylcyclohexanol.

6. The application of the power battery insulating pressure-sensitive adhesive as described in any one of claims 1-3 in the preparation of power batteries.

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