Heat-conducting structural adhesive for power battery and preparation method of heat-conducting structural adhesive

Abstract

The invention relates to the technical field of new energy automobile power battery modules, in particular to a heat-conducting structural adhesive for a power battery and a preparation method thereof.The heat-conducting structural adhesive comprises a component A and a component B. The component A is prepared from 40-50 parts of siloxane-terminated polyether resin, 110-130 parts of heat-conducting filler, 0.4-0.6 part of a curing agent, 0.2-0.4 part of a coupling agent and 0.3-0.7 part of a water removal agent; the component B is prepared from the following components in parts by weight: 17 to 23 parts of epoxy resin, 45 to 55 parts of heat-conducting filler, 0.01 to 0.03 part of modified graphene oxide, 0.8 to 1.2 parts of water, 0.4 to 0.8 part of thixotropic agent, 0.3 to 0.7 part of adhesion promoter, 1 to 1.4 parts of coupling agent, 0.1 to 0.5 part of defoaming agent and 0.3 to 0.5 part of catalyst; the heat-conducting structural adhesive has the advantages that the heat-conducting property of the heat-conducting structural adhesive is improved, and the tensile strength is kept.

Description

Technical Field

[0001] The present application relates to the technical field of power battery modules for new energy vehicles, and in particular to a thermally conductive structural adhesive for power batteries and a preparation method thereof. Background Art

[0002] With the development and upgrading of new energy vehicles, the energy density and battery capacity of their power batteries are increasingly required. The energy density of a single power battery cell is also correspondingly increased. The power battery module generates more and more heat during operation. Long-term high temperature will cause certain damage to the power battery, affecting the driving range of new energy vehicles. At present, the power battery modules of new new energy vehicles are equipped with water-cooled active cooling systems to solve the above problems.

[0003] The structural battery packs used in new energy vehicles omit or largely omit the intermediate module components in design, and instead use a large amount of glue to connect and fix the battery cells. The application of these glues has two main requirements: the first type is structural glue, which is mainly used for structural bonding and takes into account a certain degree of thermal conductivity; the second type is thermal conductive glue, which is mainly used for thermal conductive bonding. The purpose of the adhesive application is to conduct the heat between the battery cells and the battery cells, and between the battery cells and the liquid cooling tubes when the battery cells are working to the external heat dissipation components, so as to achieve some functions of thermal management and take into account the requirements of structural bonding.

[0004] However, the existing thermally conductive structural adhesive has insufficient thermal conductivity. If too much thermally conductive filler is added, the interfacial tension between the thermally conductive filler and the system will be large, which will reduce the tensile strength of the thermally conductive structural adhesive and is not conducive to the application of the thermally conductive structural adhesive. Summary of the invention

[0005] In order to improve the thermal conductivity of a thermally conductive structural adhesive and simultaneously maintain its tensile strength, the present application provides a thermally conductive structural adhesive for a power battery and a preparation method thereof.

[0006] In the first aspect, the present application provides a thermally conductive structural adhesive for a power battery, which adopts the following technical solution: A thermally conductive structural adhesive for a power battery, comprising a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 40-50 parts of a siloxane-terminated polyether resin, 110-130 parts of a thermally conductive filler, 0.4-0.6 parts of a curing agent, 0.2-0.4 parts of a coupling agent, and 0.3-0.7 parts of a dehydrating agent; The B component comprises the following raw materials in parts by weight: 17-23 parts of epoxy resin, 45-55 parts of thermal conductive filler, 0.01-0.03 parts of modified graphene oxide, 0.8-1.2 parts of water, 0.4-0.8 parts of thixotropic agent, 0.3-0.7 parts of adhesion promoter, 1-1.4 parts of coupling agent, 0.1-0.5 parts of defoaming agent and 0.3-0.5 parts of catalyst; the modified graphene oxide is prepared by grafting graphene oxide with amino-terminated hyperbranched polyamide, reacting with polychlorophosphazene, and then reacting with glycidol.

[0007] By adopting the above technical scheme, the siloxane-terminated polyether resin in component A and the water in component B can react and cross-link and cure; the curing agent in component A and the epoxy resin in component B can achieve cross-linking and curing. Through two different types of curing, the two-component structural adhesive can achieve multiple cross-linking during curing to form a cross-linking network, thereby having excellent cross-linking density and improving tensile strength. The graphene oxide is modified, and an amino-terminated hyperbranched polyamide is grafted onto the carboxyl group contained in the graphene oxide, and then the amino-terminated hyperbranched polyamide molecule terminal contains an epoxy group through a designed reaction; the graphene oxide grafted hyperbranched molecule can increase the distance between its molecules and increase its dispersibility; the epoxy group contained in the graphene oxide can participate in the cross-linking reaction of the thermal conductive structural adhesive, thereby greatly reducing the interfacial tension between the graphene oxide and the system, and making the thermal conductive structural adhesive more integrated; and the hyperbranched polymer has more terminal branches and more epoxy groups, so that after cross-linking, the graphene oxide provides more cross-linking center points, thereby greatly improving the cross-linking density of the thermal conductive structural adhesive; under multiple effects, the tensile strength of the thermal conductive structural adhesive is greatly improved, and after cold and hot treatment, the tensile strength retention rate is excellent, which improves the service life of the power battery, and at the same time, due to the improved integrity of the thermal conductive structural adhesive, its elongation at break is less affected; at the same time, the excellent thermal conductivity of the graphene oxide greatly improves the thermal conductivity of the thermal conductive structure.

[0008] Preferably, the added amount of the modified graphene oxide is 0.02 parts by weight.

[0009] By adopting the above technical solution, the addition amount is 0.02 parts by weight, which is the optimal addition amount. The obtained thermally conductive structural adhesive is more suitable for use in power batteries in terms of comprehensive performance.

[0010] Preferably, the preparation method of the modified graphene oxide is as follows: S1, using DMF as solvent, adding 0.3-0.5 parts by weight of graphene oxide, and after ultrasonic dispersion, sequentially adding 9-13 parts by weight of amino-terminated hyperbranched polyamide, 0.4-0.6 parts by weight of 4-dimethylaminopyridine and 0.4-0.6 parts by weight of N,N-dicyclohexylcarbodiimide, heating to 85-95° C., stirring and reacting for 20-28 hours, to obtain graphene oxide grafted amino-terminated hyperbranched polymer; S2, dispersing the graphene oxide grafted amino-terminated hyperbranched polymer in tetrahydrofuran, and after ultrasonic dispersion, adding 45-55 parts by weight of an acid binding agent under a nitrogen atmosphere; then dissolving 19-22 parts by weight of hexachlorocyclotriphosphazene in tetrahydrofuran and adding dropwise to the reaction system, and continuing the reaction for 9-11 hours; S3, dissolving 50-60 parts by weight of glycidol in tetrahydrofuran, adding it dropwise to the reaction system of S2, stirring and reacting at 15-40° C. for 13-18 hours, and filtering under reduced pressure to obtain modified graphene oxide.

[0011] By adopting the above technical scheme, graphene oxide is combined with the amino-terminated hyperbranched polyamide through an amide reaction via the carboxyl group in the molecular structure, and then the amino group contained in the amino-terminated hyperbranched polymer grafted with graphene oxide reacts with hexachlorocyclotriphosphazene through nucleophilic substitution, and finally the epoxy group is grafted to the end of the hyperbranched polymer branch chain through glycidol.

[0012] Preferably, the molecular weight of the amino-terminated hyperbranched polymer is 800-1000.

[0013] By adopting the above technical solution, the molecular weight of the amino-terminated hyperbranched polyamide was discussed, and its molecular weight was preferably 800-1000. It is speculated that due to its low molecular weight, it is not conducive to the subsequent formation of a denser cross-linked network, and the interaction between graphene oxide and the system is insufficient. However, when its molecular weight continues to increase, due to its large molecular volume and the steric hindrance of the reaction, the number of hyperbranched polyamide molecules grafted with graphene oxide is small, which affects the grafting rate and also affects its cross-linking density.

[0014] Preferably, the polychlorinated phosphazene is hexachlorocyclotriphosphazene.

[0015] By adopting the above technical scheme, the molecule contains elements such as phosphorus and has a ring structure. After modification, not only can more epoxy groups be obtained through reaction, but also the flame retardant properties of the thermally conductive structural adhesive can be improved. Based on the hyperbranched grafting of graphene oxide and hexachlorocyclotriphosphazene in the modified graphene and the specific molecular structures of the two components, dispersed and continuous flame retardant points can be formed, thereby improving the flame retardancy of the structural adhesive and the safety factor of the power battery.

[0016] Preferably, the acid binding agent is triethylamine.

[0017] By adopting the above technical solution, triethylamine has good solubility and can effectively capture the acidic substances generated during the reaction, thereby promoting the forward reaction, and at the same time its price is relatively low.

[0018] Preferably, the coupling agents in the component A and the component B are both epoxy-containing silane coupling agents.

[0019] By adopting the above technical solution, the interfacial tension between the stepless particles and the system can be reduced, and the stepless particles can also participate in the cross-linking reaction of the system, so that the integrity of the thermal conductive structural adhesive is stronger.

[0020] In a second aspect, the present application provides a method for preparing a thermally conductive structural adhesive for a power battery, which adopts the following technical scheme: A method for preparing a thermally conductive structural adhesive for a power battery, comprising the following steps: S1. Add the siloxane-terminated polyether resin, ammonia curing agent, coupling agent and thermal conductive filler in component A into a reaction container, evacuate and stir, then cool to below 40° C., and after measuring the water content to be below 700 ppm, add a dehydrating agent, continue evacuating and stirring to obtain a mixture of component A; S2, adding the epoxy resin, thermal conductive filler, modified graphene oxide adhesion promoter, coupling agent, and thixotropic agent in component B into a reaction container, vacuuming and stirring, and then adding a catalyst, a defoaming agent, and water, stirring evenly to obtain a mixture of component B; S3. When using, mix the mixture of component A and component B in a mass ratio of (1.8-2.2):1 and use evenly.

[0021] By adopting the above technical scheme, the preparation method of the present application does not add new steps due to the addition of the modified catalyst. It only needs to be stirred and mixed in the order of addition. The preparation method is relatively conventional, has a high tolerance for process parameters, and the qualified rate of the obtained products is high, which is suitable for large-scale production.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. Cross-linking is achieved through two different main cross-linking reactions to form a multi-cross-linked network with good elasticity and high toughness, thereby improving the tensile strength of the structural adhesive; graphene oxide is modified, and amino-terminated hyperbranched polyamide is grafted onto the carboxyl groups it contains, and then the amino-terminated hyperbranched polyamide molecules are provided with epoxy groups at the ends through a designed reaction; the graphene oxide is grafted with hyperbranched molecules to increase the distance between its molecules and increase its dispersibility; the epoxy groups it contains can participate in the cross-linking reaction of the thermal conductive structural adhesive, thereby greatly reducing the interfacial tension between it and the system, thereby improving the thermal conductive structural adhesive. The integrity is stronger; and the hyperbranched polymer has more terminal branches and more epoxy groups, so that after cross-linking, graphene oxide provides more cross-linking points, thereby greatly improving the cross-linking density of the thermally conductive structural adhesive; under various effects, the tensile strength of the thermally conductive structural adhesive is greatly improved, and after hot and cold treatment, its tensile strength retention rate is excellent, which improves the service life of the power battery. At the same time, due to the improved integrity of the thermally conductive structural adhesive, its elongation at break is less affected; at the same time, the excellent thermal conductivity of graphene oxide greatly improves the thermal conductivity of the thermally conductive structure.

[0023] 2. The tensile strength of the thermally conductive structural adhesive for power batteries prepared in the present application is between 8.21-11.25 MPa, and the tensile strength retention rate after hot and cold shock is 89.6% or above, and the maximum can reach 94.3%; the elongation at break is also 116% or above, and the maximum can reach 223%; and its thermal conductivity is between 1.37-1.94; This shows that the thermally conductive structural adhesive of the present application has excellent thermal conductivity and tensile strength, and has great application potential in power batteries. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with the specific contents.

[0025] raw material The raw materials used in the preparation examples and embodiments of this application were purchased from commercial sources. The graphene oxide had a thickness of about 1 nm, a number of layers of 1-2, an average diameter of 30 μm, and a specific surface area of ​​200 m 2 / g, purity>95wt%; dimethoxysilane-terminated polyether and trimethoxysilane-terminated polyether were purchased from Zhangjiagang Top Chemical Co., Ltd.; the thermal conductive filler was alumina with a particle size range of 20-40μm; the curing agent was an epoxy resin curing agent with a model of T31; the coupling agent was KH560; the dehydrating agent was vinyltrimethoxysilane; the epoxy resin was a bisphenol A type epoxy resin with a model of T44; the thixotropic agent was hydrogenated castor oil with a model of MT; the adhesion promoter was model 6088; the defoaming agent was a silicone defoaming agent with a model of CI-0560; and the catalyst was dibutyltin dilaurate.

[0026] Preparation Example Preparation Example 1 A modified graphene oxide, the preparation method of which is as follows: S1. Add 0.4 g of graphene oxide to 500 mL of DMF, ultrasonically disperse for 20 min, then add 11 g of amino-terminated hyperbranched polyamide, 0.5 g of 4-dimethylaminopyridine (DMAP) and 0.5 g of N,N-dicyclohexylcarbodiimide (DCC) in sequence, stir until dissolved, then heat to 90 ° C, stir and react for 24 h, let stand and cool to room temperature, filter under reduced pressure, wash with DMF and ethanol for 3 times respectively, to obtain graphene oxide grafted amino-terminated hyperbranched polymer; the molecular weight of amino-terminated hyperbranched polyamide is 350-370, and the corresponding model specification is HyPer N101; S2, dispersing the graphene oxide grafted amino-terminated hyperbranched polymer in 500 mL of tetrahydrofuran, ultrasonically dispersing for 10 min, adding 50 g of triethylamine under a nitrogen atmosphere, and stirring for 20 min; then dissolving 21 g of hexachlorocyclotriphosphazene in 150 mL of tetrahydrofuran, and then uniformly dropping it into the reaction system, and after the dropwise addition is completed, continuing to react in a nitrogen atmosphere for 10 h; S3, dissolving 56 g of glycidol in 200 mL of tetrahydrofuran, and uniformly adding it dropwise to the reaction system of S2 within 1 hour. After the addition is completed, stirring and reacting at room temperature for 15 hours. After the reaction is completed, filtering under reduced pressure, and washing with tetrahydrofuran and deionized water for 3 times respectively to remove impurities such as acid binding agent and hydrochloride, to obtain modified graphene oxide containing epoxy groups.

[0027] Preparation Example 2 A modified graphene oxide, which is different from Preparation Example 1 in that the molecular weight of its terminal amino hyperbranched polyamide is 800-1000, the corresponding model specification is HyPer N102, and the remaining steps are the same as Preparation Example 1.

[0028] Preparation Example 3 A modified graphene oxide, which is different from Preparation Example 1 in that the molecular weight of its terminal amino hyperbranched polyamide is 1900-2200, the corresponding model specification is HyPer N103, and the remaining steps are the same as Preparation Example 1. Example

[0029] Example 1 A thermally conductive structural adhesive for a power battery, comprising a component A and a component B, wherein the component A comprises the following raw materials in parts by mass: 20 g of a dimethoxysilane-terminated polyether, 25 g of a trimethoxysilane-terminated polyether, 120 g of a thermally conductive filler, 0.5 g of a curing agent, 0.3 g of a coupling agent, and 0.5 g of a dehydrating agent; the component B comprises the following raw materials in parts by mass: 20 g of an epoxy resin, 50 g of a thermally conductive filler, 0.02 g of modified graphene oxide, 1 g of water, 0.6 g of a thixotropic agent, 0.5 g of an adhesion promoter, 1.2 g of a coupling agent, 0.3 g of a defoaming agent, and 0.4 g of a catalyst; wherein the modified graphene oxide is from Preparation Example 1; The preparation method of thermal conductive structural adhesive for power battery is as follows: S1. Add the siloxane-terminated polyether resin, curing agent, coupling agent and thermal conductive filler in component A into a reaction container, vacuumize and stir for 2 hours, then cool to below 40° C., and after measuring the water content to be below 700 ppm, add a dehydrating agent, continue vacuumizing and stirring for 30 minutes, and obtain a mixture of component A; S2, adding the epoxy resin, thermal conductive filler, modified graphene oxide, adhesion promoter, coupling agent and thixotropic agent in component B into a reaction container, vacuuming and stirring for 1 hour, then adding the catalyst, defoaming agent and water, and continuing stirring for 30 minutes to obtain a mixture of component B; S3. When using, mix the mixture of component A and the mixture of component B in a mass ratio of 2:1 and use evenly.

[0030] Example 2 A thermally conductive structural adhesive for a power battery, which is different from Example 1 in that the modified graphene oxide comes from Preparation Example 2, and the remaining steps are the same as those of Example 1.

[0031] Example 3 A thermally conductive structural adhesive for a power battery, which is different from Example 1 in that the modified graphene oxide comes from Preparation Example 3, and the remaining steps are the same as those of Example 1.

[0032] Example 4 A thermally conductive structural adhesive for a power battery, which is different from Example 2 in that the added amount of modified graphene oxide is 0.01 g, and the remaining steps are the same as those in Example 2.

[0033] Example 5 A thermally conductive structural adhesive for a power battery, which is different from Example 2 in that the added amount of modified graphene oxide is 0.03 g, and the remaining steps are the same as Example 2.

[0034] Comparative Example Comparative Example 1 A thermally conductive structural adhesive for a power battery, which is different from Example 1 in that modified graphene oxide is not added to its component B, and the remaining steps are the same as those of Example 1.

[0035] Comparative Example 2 A thermally conductive structural adhesive for a power battery, which is different from Example 1 in that its modified graphene oxide is replaced by graphene oxide of equal mass, and the remaining steps are the same as those of Example 1.

[0036] Comparative Example 3 A thermally conductive structural adhesive for a power battery is different from Example 1 in that, during the preparation of its modified graphene oxide, the terminal amino hyperbranched polymer is replaced by ethylenediamine, the amount of hexachlorocyclotriphosphazene added is 8 g, the amount of triethylamine added is 11 g, and the remaining steps are the same as in Example 1.

[0037] Performance testing Detection method / test method Thermally conductive structural adhesives for power batteries were prepared according to the preparation methods of Examples 1-5 and Comparative Examples 1-3, and then tested according to the following testing methods. The test results are shown in Table 1.

[0038] Tensile strength and elongation at break: Tested in accordance with the test method in GBT 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber"; and tested for tensile strength after hot and cold shock. The hot and cold shock test is as follows: Use a hot and cold shock tester to continuously expose at -40°C for 1 hour, then quickly switch to 85°C for 1 hour, repeat this cycle 1000 times, and calculate the tensile strength retention rate; Thermal conductivity: Tested according to the test method in ASTM-D-5470-06 "Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials".

[0039] Table 1 Test results of Examples 1-5 and Comparative Examples 1-3 It can be seen from Examples 1-5 and Comparative Examples 1-3, as well as the test data in Table 2, that the tensile strength of the thermally conductive structural adhesive for power batteries prepared in the present application is between 8.21-11.25 MPa, and the tensile strength retention rate after hot and cold shock is 89.6% and above, with a maximum of 94.3%; the elongation at break is also 116% and above, with a maximum of 223%; and its thermal conductivity is between 1.37-1.94; this indicates that the thermally conductive structural adhesive of the present application has excellent thermal conductivity and tensile strength, and has great application potential in power batteries.

[0040] When graphene oxide is added to the thermal conductive structure system, it is found that although it can improve the thermal conductivity and mechanical strength of the thermal conductive structural adhesive, it cannot achieve the expected effect due to its interface performance with the system and its own easy aggregation. Increasing its addition amount, due to its excellent mechanical properties, the elongation at break of the thermal conductive structural adhesive decreases rapidly, which limits its application. On this basis, the inventor of the present application modified graphene oxide, grafted amino-terminated hyperbranched polyamide on the carboxyl group it contained, and then designed a reaction to make the amino-terminated hyperbranched polyamide molecule end contain epoxy groups; Graphene oxide grafted hyperbranched molecules can increase the distance between its molecules and increase its dispersibility; the epoxy groups it contains can participate in the cross-linking reaction of the thermally conductive structural adhesive, so that the interfacial tension between it and the system is greatly reduced, making the integrity of the thermally conductive structural adhesive stronger; and the terminal branches of the hyperbranched polymer are more, and the more epoxy groups, so that after cross-linking, graphene oxide provides more cross-linking points, thereby greatly improving the cross-linking density of the thermally conductive structural adhesive; under various effects, the tensile strength of the thermally conductive structural adhesive is greatly improved, and after cold and hot treatment, its tensile strength retention rate is excellent, which improves the service life of the power battery, and at the same time, due to the improvement of the integrity of the thermally conductive structural adhesive, its elongation at break is less affected; at the same time, the excellent thermal conductivity of graphene oxide greatly improves the thermal conductivity of the thermally conductive structure. It can be verified by the test data of Example 1 and Comparative Examples 1-2.

[0041] On this basis, by discussing the molecular weight of the amino-terminated hyperbranched polyamide, its molecular weight is preferably 800-1000. It is speculated that due to its low molecular weight, the interaction between graphene oxide and the system is insufficient. However, when its molecular weight continues to increase, due to its large molecular volume and the steric hindrance of the reaction, the number of hyperbranched polyamide molecules grafted with graphene oxide is less, which also affects its cross-linking density. It can be seen from the test data of Examples 1-3. In combination with Examples 4-5, the addition amount of 0.02kg is the optimal addition amount, and the obtained thermally conductive structural adhesive is more suitable for the use of power batteries in terms of comprehensive performance.

[0042] It can be seen from the test data of Example 1 and Comparative Example 3 that the cross-linking density of the modified graphene oxide using ordinary straight-chain structured ethylenediamine is relatively small; compared with the modified graphene oxide of the embodiment of the present application, its technical effect is insufficient.

[0043] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A thermally conductive structural adhesive for a power battery, characterized in that: It comprises component A and component B, wherein component A comprises the following raw materials in parts by weight: 40-50 parts of siloxane-terminated polyether resin, 110-130 parts of thermal conductive filler, 0.4-0.6 parts of curing agent, 0.2-0.4 parts of coupling agent, and 0.3-0.7 parts of dehydrating agent; The B component comprises the following raw materials in parts by weight: 17-23 parts of epoxy resin, 45-55 parts of thermal conductive filler, 0.01-0.03 parts of modified graphene oxide, 0.8-1.2 parts of water, 0.4-0.8 parts of thixotropic agent, 0.3-0.7 parts of adhesion promoter, 1-1.4 parts of coupling agent, 0.1-0.5 parts of defoaming agent and 0.3-0.5 parts of catalyst; the modified graphene oxide is prepared by grafting graphene oxide with amino-terminated hyperbranched polyamide, reacting with polychlorophosphazene, and then reacting with glycidol.

2. The thermally conductive structural adhesive for a power battery according to claim 1, characterized in that: The added amount of the modified graphene oxide is 0.02 parts by weight.

3. The thermally conductive structural adhesive for a power battery according to claim 1, characterized in that: The preparation method of the modified graphene oxide is as follows: S1, using DMF as solvent, adding 0.3-0.5 parts by weight of graphene oxide, and adding 9-13 parts by weight of amino-terminated hyperbranched polyamide, 0.4-0.6 parts by weight of 4-dimethylaminopyridine and 0.4-0.6 parts by weight of N,N-dicyclohexylcarbodiimide in sequence after ultrasonic dispersion, heating to 85-95° C., stirring and reacting for 20-28 hours, to obtain graphene oxide grafted amino-terminated hyperbranched polymer; S2, dispersing the graphene oxide grafted amino-terminated hyperbranched polymer in tetrahydrofuran, and after ultrasonic dispersion, adding 45-55 parts by weight of an acid binding agent under a nitrogen atmosphere; then dissolving 19-22 parts by weight of hexachlorocyclotriphosphazene in tetrahydrofuran and adding dropwise to the reaction system, and continuing the reaction for 9-11 hours; S3, dissolving 50-60 parts by weight of glycidol in tetrahydrofuran, adding it dropwise to the reaction system of S2, stirring and reacting at 15-40° C. for 13-18 hours, and filtering under reduced pressure to obtain modified graphene oxide.

4. The thermally conductive structural adhesive for a power battery according to claim 1, characterized in that: The molecular weight of the amino-terminated hyperbranched polymer is 800-1000.

5. The thermally conductive structural adhesive for a power battery according to claim 1, characterized in that: The polychlorinated phosphazene is hexachlorocyclotriphosphazene.

6. The thermally conductive structural adhesive for a power battery according to claim 3, characterized in that: The acid binding agent is triethylamine.

7. The thermally conductive structural adhesive for a power battery according to claim 1, characterized in that: The coupling agents in the component A and the component B are both epoxy-containing silane coupling agents.

8. A method for preparing the thermally conductive structural adhesive for power batteries according to any one of claims 1 to 7, characterized in that: It includes the following steps: S1. Add the siloxane-terminated polyether resin, curing agent, coupling agent and thermal conductive filler in component A into a reaction container, evacuate and stir, then cool to below 40° C., and after measuring the water content to be below 700 ppm, add a dehydrating agent, continue evacuating and stirring to obtain a mixture of component A; S2, adding the epoxy resin, thermal conductive filler, modified graphene oxide, adhesion promoter, coupling agent, and thixotropic agent in component B into a reaction container, vacuuming and stirring, then adding a catalyst, a defoaming agent, and water, stirring evenly, to obtain a mixture of component B; S3. When using, mix the mixture of component A and component B in a mass ratio of (1.8-2.2):1 and use evenly.

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