Polyrotaxane-modified polyethylene sheath composite structure energy storage cable and preparation method thereof

Abstract

The polyrotaxane modified polyethylene sheath composite structure energy storage cable and the preparation method thereof, through the synergistic design of carbon fiber-copper composite conductor, nanofluid active heat dissipation, double-layer broadband shielding and polyrotaxane modified polyethylene sheath, the problems of poor heat dissipation, strong electromagnetic interference, easy aging and insufficient sheath performance of the traditional cable are solved. 6 The cable current carrying capacity is increased by 38.9%, the temperature rise is reduced by 60%, the bending life is greater than 5*10 6 Times, and is suitable for high requirement scenes such as new energy power station and electric vehicle fast charging.

Description

Technical Field

[0001] This invention relates to the field of power transmission technology, and more specifically, to a composite energy storage cable with a polyrotaxane-modified polyethylene sheath and its preparation method. Background Technology

[0002] Energy storage cables are high-performance cables specifically designed to connect energy storage systems (such as battery packs, supercapacitors, flywheel energy storage devices, etc.) to power networks or load equipment, undertaking functions such as power transmission, signal control, and system protection. Their core characteristics include the need to meet special requirements such as high power density, frequent charging and discharging, and adaptability to extreme environments.

[0003] Traditional energy storage cables have the following defects: 1) Electromagnetic interference (EMI): The pulse current generated by the frequent charging and discharging of the energy storage system causes electromagnetic radiation (40dB exceeding the standard in the 30MHz-1GHz band); 2) Mechanical fatigue and corrosion: Long-term bending or humid and hot environment can easily lead to conductor breakage and sheath cracking (resistance change rate >5% after 500 hours of salt spray test); 3) Insufficient sheath material performance: Traditional polyethylene sheath has poor flexibility and low fatigue resistance, making it difficult to meet the requirements of frequent bending.

[0004] Therefore, it is necessary to propose a composite energy storage cable with polyrotaxane-modified polyethylene sheath, its preparation method, and its application method to solve the problems of poor electromagnetic interference resistance and low mechanical strength of existing energy storage cables. Summary of the Invention

[0005] This invention provides a composite structure energy storage cable with polyrotaxane-modified polyethylene sheath, its preparation method, and its usage method, in order to solve the problems of strong electromagnetic interference, short mechanical life, and easy aging of the sheath in existing energy storage cables.

[0006] According to one aspect of the present invention, a composite structure energy storage cable with a polyrotaxane-modified polyethylene sheath is provided, comprising a double-layer electromagnetic shielding layer and a polyrotaxane-modified polyethylene sheath, wherein the polyrotaxane-modified polyethylene sheath is fitted onto the surface of the double-layer electromagnetic shielding layer, and the polyrotaxane-modified polyethylene sheath is a material obtained by kneading a dynamic network of grafted cyclodextrin-based polyrotaxane in an HDPE substrate with boron nitride nanosheets and tire rubber powder.

[0007] Based on the above scheme, the preferred embodiment is that the double-layer electromagnetic shielding layer includes an inner layer and an outer layer, wherein the inner layer is a silver-plated copper wire braided layer with an inner layer coverage of ≥95%, and the outer layer is a ferrite-silicone rubber composite coating with a thickness of 0.5-1mm and a ferrite mass ratio of 50%-70%.

[0008] Based on the above scheme, the preferred embodiment is that the elongation at break of the polyrotaxane-modified polyethylene sheath is ≥350%, and the self-healing efficiency is ≥80%.

[0009] The present invention also provides a method for preparing the polyrotaxane-modified polyethylene sheath, comprising the following steps:

[0010] Step 1. High-density polyethylene (HDPE) and maleic anhydride (MAH) are mixed at a mass ratio of 98:2. 0.8 wt% dicumyl peroxide (DCP) is added as an initiator. The mixture is melt-blended in an internal mixer at 190°C for 10 minutes to obtain maleic anhydride-grafted polyethylene (PE-g-MAH).

[0011] Step 2. Cyclodextrin-based polyrotaxane and 3-mercaptopropionic acid (MPA) were mixed at a molar ratio of 1:1.2, and N,N'-dicyclohexylcarbodiimide (DCC) catalyst was added. The mixture was reacted at room temperature for 24 hours, and the mercapto-based polyrotaxane (PR-SH) was obtained after dialysis purification with a thiol content of 2.3 mmol / g.

[0012] Step 3. Thiol-anhydride reaction: After PR-SH is fully dried, PE-g-MAH and PR-SH are added to a mixer at a mass ratio of 85:15, along with 1 wt% 1,8-diazabicycloundec-7-ene (DBU) and 2 wt% antioxidant 1010. The mixture is reacted at 160°C for 10 minutes to form a covalent cross-linked network.

[0013] Step 4. Immerse the product in a 3% hydrogen peroxide solution for 6 hours to oxidize it, and then wash and dry it to obtain a sheath material containing dynamic disulfide bonds;

[0014] Step 5. Mix boron nitride nanosheets and waste tire rubber powder with PE-PR-SS at 180°C for 15 minutes to obtain the final sheath material.

[0015] Based on the above scheme, the preferred dynamic crosslinking density in step 3 is 0.5-1.5 mol / m³. 3 .

[0016] Based on the above scheme, the preferred option is that the boron nitride nanosheets in step 5 have a particle size of 50-150 nm and a volume percentage of 5%-10%.

[0017] Based on the above scheme, the preferred option is that the particle size of the waste tire rubber powder in step 5 is 60-250 mesh, and the volume percentage is 10%-15%.

[0018] This invention relates to a composite energy storage cable with a polyrotaxane-modified polyethylene sheath and its preparation method. Through the synergistic design of a carbon fiber-copper composite conductor, nanofluid active heat dissipation, double-layer broadband shielding, and a polyrotaxane-modified polyethylene sheath, it solves the problems of poor heat dissipation, strong electromagnetic interference, easy aging, and insufficient sheath performance in traditional cables. This cable exhibits a 38.9% increase in current carrying capacity, a 60% reduction in temperature rise, and a bending life >5×10⁻⁶. 6This technology is suitable for high-requirement scenarios such as new energy power plants and fast charging of electric vehicles. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] In the picture:

[0021] Figure 1 This is a schematic diagram of the composite structure energy storage cable of the present invention;

[0022] Figure 2 This is a schematic diagram of the microstructure of the polyrotaxane-modified polyethylene sheath of the present invention;

[0023] Figure 3 The reaction equation for the thiol-anhydride grafting reaction of the present invention is as follows:

[0024] Figure 4 This is a diagram showing the setup for the shielding effectiveness test of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of a descriptive feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets.

[0027] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0028] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various components of the invention are relative rather than absolute. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, these directional indications also change accordingly.

[0030] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0032] Please see Figure 1 and combined Figure 2 and Figure 3 As shown, the present invention discloses a composite structure energy storage cable with a polyrotaxane-modified polyethylene sheath, comprising a double-layer electromagnetic shielding layer covering the core layer 1 and a polyrotaxane-modified polyethylene sheath 4. The polyrotaxane-modified polyethylene sheath 4 is mounted on the surface of the double-layer electromagnetic shielding layer, and the polyrotaxane-modified polyethylene sheath 4 is a material obtained by intensive mixing of a cyclodextrin-based polyrotaxane dynamic network grafted in an HDPE substrate with boron nitride nanosheets and tire rubber powder.

[0033] Specifically, the double-layer electromagnetic shielding layer of the present invention includes an inner layer and an outer layer. The inner layer is a silver-plated copper wire braided layer 2 with an inner layer coverage of ≥95%. The outer layer is a ferrite-silicone rubber composite coating 3 with a thickness of 0.5-1mm and a ferrite mass ratio of 50%-70%. Through the broadband synergistic shielding of the silver-plated copper wire braided layer 2 and the ferrite-silicone rubber composite coating 3, a radiation reduction of 40dB is achieved.

[0034] The polyrotaxane-modified polyethylene sheath of the present invention has an elongation at break of ≥350% and a self-healing efficiency of ≥80%. It achieves self-healing function through dynamic disulfide bonds, while improving flexibility and weather resistance.

[0035] The present invention also provides a method for preparing the polyrotaxane-modified polyethylene sheath, comprising the following steps:

[0036] Step 1. Olefinification modification of polyethylene: High-density polyethylene (HDPE) and maleic anhydride (MAH) are mixed at a mass ratio of 98:2, and 0.8 wt% dicumyl peroxide (DCP) is added as an initiator;

[0037] Maleic anhydride-grafted polyethylene (PE-g-MAH) was obtained by melt-blending at 190°C for 10 minutes in an internal mixer.

[0038] Step 2. Thiolization of cyclodextrin-based polyrotaxane: Cyclodextrin-based polyrotaxane (β-CD-PEG-PR, Mn = 2 × 10⁻⁶) is thiolated. 5 The mixture of 3-mercaptopropionic acid (MPA) and N,N'-dicyclohexylcarbodiimide (DCC) catalyst was added. The reaction was carried out at room temperature for 24 hours. After purification by dialysis, thiolated polyrotaxane (PR-SH) was obtained with a thiol content of 2.3 mmol / g. The specific reaction formula is as follows:

[0039] Step 3. Thiol-Anhydride Grafting: After thoroughly drying PR-SH, add PE-g-MAH and PR-SH to a mixer at a mass ratio of 85:15, along with 1 wt% 1,8-diazabicycloundec-7-ene (DBU) and 2 wt% antioxidant 1010. React at 160°C for 10 minutes. The specific reaction formula is as follows: Figure 3 As shown.

[0040] Step 4. Dynamic disulfide bond oxidation: The product is immersed in a 3% hydrogen peroxide solution for 6 hours for oxidation, and after washing and drying, a sheath material containing dynamic disulfide bonds (PE-PR-SS) is obtained.

[0041] Step 5. Filler blending: Boron nitride nanosheets (h-BN, particle size 100nm, 8wt%) and waste tire rubber powder (250 mesh, 12wt%) are mixed with PE-PR-SS at 180℃ for 15 minutes to obtain the final sheath material.

[0042] To verify the product performance of the present invention, product tests will be conducted on the products prepared in the above embodiments and conventional cables.

[0043] This traditional cable can be provided with a specific manufacturer and model number;

[0044] For comparison, the cable manufacturer is Guangdong Ronglan, and the cable model is ES-RYJYJ-125. The conductor is multi-strand copper wire, and the insulation and sheath materials are both low-smoke halogen-free flame-retardant heat-resistant 125℃ cross-linked polyolefin.

[0045] First, the current carrying capacity and temperature rise of the cable are tested. Specifically, the current carrying capacity of the cable is calculated using the equivalent thermal circuit method. By equating the heat conduction path of the cable to a circuit model, the temperature rise and current carrying capacity of the cable are calculated using parameters such as thermal resistance and thermal capacity.

[0046] The thermal resistance of a cable includes: conductor thermal resistance, insulation thermal resistance, sheath thermal resistance, and external environmental thermal resistance.

[0047] The formula for calculating thermal resistance is:

[0048] Where: r1 represents the radius of the inner layer material, r2 represents the radius of the outer layer material; λ represents the thermal conductivity of the material.

[0049] The formula for calculating heat capacity is: C = cρV;

[0050] Where: c is the specific heat capacity of the material; ρ is the density of the material; V is the volume of the material.

[0051] First, based on the cable structure, determine the connection method for thermal resistance and thermal capacity, and calculate the thermal resistance and thermal capacity of each layer of the cable material.

[0052] Then, based on the load current and thermal resistance, calculate the temperature rise of the cable: ΔT = I²·R th ;

[0053] Where: I is the load current; R th This is the total thermal resistance.

[0054] Finally, based on the temperature rise results, the load current is adjusted until the temperature rise reaches the maximum allowable temperature of the cable, so as to obtain the current carrying capacity and temperature rise of the conventional cable and the cable prepared by the method of the present invention, respectively.

[0055] To further verify the bending life of the cable, a bending test will be conducted to measure the bending life of conventional cables and cables prepared by the method of this invention.

[0056] For specific test methods, please refer to JB / T10696.3-2007, the steps of which are as follows:

[0057] 1) The bending test should be carried out at a temperature of (20±5)℃;

[0058] 2) The diameter of the cylinder used in the test is 20(D+d), where D is the nominal outer diameter of the cable and d is the nominal diameter of the conductor. The diameter of the cylinder can fluctuate by 5% based on the calculation results. All units are mm.

[0059] 3) The cable specimen should be wound around the test cylinder at a uniform speed for a full turn, and this operation should take no less than 10 seconds. Then straighten the specimen and repeat the winding process in the opposite direction for a full turn, and then straighten it again, which counts as one bending operation.

[0060] To further verify the corrosion resistance of the cable, the bending life of both conventional cables and cables prepared by the method of this invention were tested using a salt spray test:

[0061] The test method for the salt spray test is in accordance with GB / T2423.17-2024.

[0062] 1) Preparation of salt solution: Dissolve sufficient sodium chloride in distilled water or deionized water with a conductivity of no more than 20 μS / cm at a temperature of 25℃±2K to prepare a concentration of 50 g / L±5 g / L.

[0063] 2) The main test equipment includes test chamber, spray device and collection device.

[0064] 3) The compressed air entering the spray device is heated and humidified as required. The commonly used humidifier is a saturation tower, whose temperature and pressure are controllable. The atomization pressure is 70 kPa to 170 kPa, and the hot water temperature in the saturation tower is 45℃ to 54℃.

[0065] 4) Use two collection devices to check the uniformity of the spray in the test chamber. The collection device consists of a collection funnel with a diameter of 100mm ± 2mm, corresponding to approximately 80cm... 2 The collection area. The funnel is made of chemically inert material, and a suitable measuring container is placed under the neck of the funnel.

[0066] 5) Test operation conditions

[0067] condition Specified value temperature 35℃±2K Average collection rate of a horizontal collection area of ​​80 cm² 1.5 mL / h ± 0.5 mL / h Sodium chloride concentration (in collected solution) 50g / L±5g / L pH (collected solution) 6.5～7.2

[0068] 6) Place the sample at an angle of 20°±5° to the vertical direction, ensuring that it does not come into contact with the test chamber, with the test surface facing upwards and exposed to the free-flowing spray. Observe the test results separately to obtain the corrosion resistance of the two samples.

[0069] To further obtain the EMI shielding effectiveness of the cable, the EMI shielding effectiveness of conventional cables and cables prepared by the method of this invention were tested in the following EMI shielding effectiveness tests:

[0070] The shielding effectiveness test method shall be carried out in accordance with Appendix F of GB / T17626.21. Please refer to the shielding effectiveness test layout diagram for the shielding test. Figure 4 As shown.

[0071] The measurement of shielding effectiveness is based on comparing the electromagnetic power outside the device under test with the electromagnetic power induced inside the device under test.

[0072] After testing the above items, the following results were obtained:

[0073]

[0074] Based on the test data, this invention demonstrates significant improvements over traditional cables (CN20XX) in several key performance indicators, as summarized and analyzed below:

[0075] This invention is in 50mm 2The current carrying capacity of the cross-sectional area reaches 250A, which is 38.9% higher than the 180A of traditional cables. This invention can carry higher current loads and is suitable for higher power applications.

[0076] Under conditions of continuous 250A current for 1 hour, the temperature rise of this invention does not exceed 18K, while the temperature rise of conventional cables is as high as 40K or more. The heat dissipation efficiency of this invention is improved by 122%, indicating that it has superior stability and safety in high-temperature environments.

[0077] The present invention achieves a lifespan exceeding 5 × 10⁻⁶ under bending conditions with a radius of 5D. 6 This is significant, whereas the lifespan of traditional cables is only 1×10⁻⁶. 6 The present invention extends the bending life by 400%, demonstrating higher mechanical durability and reliability.

[0078] In a 1000-hour salt spray test, the resistance change rate of the present invention was less than 1%, while the resistance change rate of conventional cables exceeded 5%. The corrosion resistance of the present invention is improved by 80%, indicating better long-term stability in harsh environments.

[0079] The present invention achieves an EMI shielding effectiveness of 45dB at a frequency of 1GHz, compared to 25dB for traditional cables, representing an 80% reduction in radiation. This demonstrates the superior performance of the present invention in electromagnetic interference shielding, making it suitable for scenarios with high electromagnetic compatibility requirements.

[0080] This invention significantly outperforms traditional cables in terms of current carrying capacity, temperature rise control, bending life, corrosion resistance, and EMI shielding effectiveness, resulting in a substantial improvement in overall performance. Its efficient heat dissipation, long lifespan, strong corrosion resistance, and excellent electromagnetic shielding capabilities give it a clear competitive advantage in high-power, high-reliability, and complex environments.

[0081] This invention relates to a composite energy storage cable with a polyrotaxane-modified polyethylene sheath and its preparation method. Through the synergistic design of a carbon fiber-copper composite conductor, nanofluid active heat dissipation, double-layer broadband shielding, and a polyrotaxane-modified polyethylene sheath, it solves the problems of poor heat dissipation, strong electromagnetic interference, easy aging, and insufficient sheath performance in traditional cables. This cable exhibits a 38.9% increase in current carrying capacity, a 60% reduction in temperature rise, and a bending life >5×10⁻⁶. 6 This technology is suitable for high-requirement scenarios such as new energy power plants and fast charging of electric vehicles.

[0082] Finally, the method described in this application is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A composite energy storage cable with a polyrotaxane-modified polyethylene sheath, characterized in that, It includes a double-layer electromagnetic shielding layer and a polyrotaxane-modified polyethylene sheath. The polyrotaxane-modified polyethylene sheath is fitted on the surface of the double-layer electromagnetic shielding layer. The polyrotaxane-modified polyethylene sheath is a material obtained by intensive mixing of a dynamic network of grafted cyclodextrin-based polyrotaxane in an HDPE substrate with boron nitride nanosheets and tire rubber powder. The method for preparing the polyrotaxane-modified polyethylene sheath includes the following steps: Step 1. High-density polyethylene (HDPE) and maleic anhydride (MAH) are mixed at a mass ratio of 98:

2. 0.8 wt% dicumyl peroxide (DCP) is added as an initiator. The mixture is melt-blended in an internal mixer at 190°C for 10 minutes to obtain maleic anhydride-grafted polyethylene (PE-g-MAH). Step 2. Cyclodextrin-based polyrotaxane and 3-mercaptopropionic acid (MPA) were mixed at a molar ratio of 1:1.2, and N,N'-dicyclohexylcarbodiimide (DCC) catalyst was added. The mixture was reacted at room temperature for 24 hours, and the mercapto-based polyrotaxane (PR-SH) was obtained after dialysis purification with a thiol content of 2.3 mmol / g. Step 3. After thoroughly drying PR-SH, add PE-g-MAH and PR-SH to a mixer at a mass ratio of 85:15, along with 1 wt% 1,8-diazabicycloundec-7-ene (DBU) and 2 wt% antioxidant. React at 160°C for 10 minutes to form a covalent cross-linked network. Step 4. Immerse the product in a 3% hydrogen peroxide solution for 6 hours to oxidize it, and then wash and dry it to obtain a sheath material containing dynamic disulfide bonds; Step 5. Mix boron nitride nanosheets and waste tire rubber powder with PE-PR-SS at 180°C for 15 minutes to obtain the final sheath material.

2. The composite energy storage cable with a polyrotaxane-modified polyethylene sheath as described in claim 1, characterized in that, The dual-layer electromagnetic shielding layer includes an inner layer and an outer layer. The inner layer is a silver-plated copper wire braided layer with a coverage of ≥95%. The outer layer is a ferrite-silicone rubber composite coating with a thickness of 0.5-1mm and a ferrite mass ratio of 50%-70%.

3. The composite energy storage cable with a polyrotaxane-modified polyethylene sheath as described in claim 1, characterized in that, The polyrotaxane-modified polyethylene sheath has an elongation at break of ≥350% and a self-healing efficiency of ≥80%.

4. The composite energy storage cable with a polyrotaxane-modified polyethylene sheath as described in claim 1, characterized in that, The dynamic crosslinking density in step 3 is 0.5–1.5 mol / m³.

5. The composite energy storage cable with a polyrotaxane-modified polyethylene sheath as described in claim 1, characterized in that, The boron nitride nanosheets in step 5 have a particle size of 50-150 nm and a volume percentage of 5% to 10%.

6. The composite energy storage cable with a polyrotaxane-modified polyethylene sheath as described in claim 1, characterized in that, The waste tire rubber powder in step 5 has a particle size of 60-250 mesh and a volume percentage of 10% to 15%.

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