Cycloolefin copolymer / anthracene composite dielectric thin film for high temperature energy storage

Abstract

This invention relates to the field of polymer dielectric materials and discloses a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising 100 parts by weight of a cyclic olefin copolymer and 0.2 to 1.0 parts by weight of anthracene. The anthracene is uniformly dispersed in the amorphous network interstices of the cyclic olefin copolymer, utilizing the energy difference between their lowest unoccupied molecular orbitals to construct deep trap sites. By capturing free carriers injected at the electrode interface under high temperature and strong electric field conditions, electron migration is restricted, thereby blocking leakage conduction paths within the bulk phase of the material. This invention effectively reduces Joule heat accumulation during charge transport, improves the high-temperature withstand voltage and insulation reliability of the film, while maintaining relatively low dielectric loss. This all-organic blend system avoids local electric field distortion caused by inorganic filler agglomeration, and the preparation process is simple and mild, facilitating large-scale engineering applications.

Description

Technical Field

[0001] This invention relates to the field of polymer dielectric materials, specifically to a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. Background Technology

[0002] Polymer dielectric films are widely used in the field of film capacitors due to their high breakdown field strength, good processability, and strong self-healing ability. With the miniaturization and high power density of modern electronic and electrical systems, electrical equipment in aerospace, hybrid vehicles, and underground drilling often needs to operate in high-temperature environments. This requires the dielectric material in energy storage capacitors to not only maintain good insulation at room temperature but also maintain stable energy storage density and withstand voltage levels under high-temperature conditions. Cycloolefin copolymers, as aliphatic polymers with an amorphous structure, have low dielectric loss and good thermal stability, making them one of the commonly used basic materials for preparing high-temperature dielectric films.

[0003] Under actual high-temperature and strong electric field coupling conditions, the movement of amorphous chain segments within the polymer matrix intensifies significantly, leading to a decrease in the charge injection barrier at the electrode interface. A large number of free charge carriers, such as electrons, enter the bulk dielectric material and readily jump and conduct within the network gaps, resulting in significant leakage current. This continuous charge transport process is accompanied by Joule heating. Due to the limited thermal conductivity of the polymer bulk, heat gradually accumulates within the material, easily inducing electrical tree growth and ultimately leading to thermal breakdown failure. This, to some extent, limits the reliability of polymer films in high-temperature energy storage scenarios.

[0004] To improve the insulation and withstand voltage properties of polymers under high-temperature conditions, conventional methods mainly involve adding inorganic nanofillers to the matrix or chemically grafting the polymer backbone. While adding inorganic nanomaterials can introduce traps to limit charge to some extent, there are inherent physical compatibility differences between inorganic particles and organic polymers, leading to filler agglomeration during blending. This micro-agglomeration not only disrupts the continuity of the film structure but also causes local electric field distortion at the two-phase interface, increasing the dielectric loss of the material. On the other hand, chemical grafting modification of the polymer backbone usually involves complex reaction steps and requires high overall process conditions, increasing the difficulty of large-scale continuous preparation. Furthermore, it is difficult to control the uniformity of the product during the reaction, which is detrimental to the engineering processing of large-area dielectric films. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. This solves the problems of existing polymer dielectric materials being prone to leakage current accumulation and ear heating under high temperature and strong electric field coupling conditions, which can lead to thermal breakdown failure. It also addresses the issues of traditional inorganic filler addition causing local electric field distortion due to agglomeration and complex chemical modification processes that are not easy to scale up.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, employing the following technical solution: A cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage is disclosed. The composite dielectric film is made from raw materials comprising the following parts by weight: 100 parts of cyclic olefin copolymer and 0.2 to 1.0 parts of anthracene. The anthracene is uniformly dispersed as a deep trap provider in the amorphous network interstices of the cyclic olefin copolymer. Deep trap sites are constructed by the fact that the lowest unoccupied molecular orbital energy level of the anthracene is lower than that of the lowest unoccupied molecular orbital energy level of the cyclic olefin copolymer, so as to capture injected free carriers under high temperature and strong electric field conditions, thereby suppressing leakage current inside the composite film and preventing thermal breakdown caused by Joule thermal accumulation.

[0007] By employing the above technical solution, a molecular-level trap energy level network is constructed by physically doping anthracene molecules into the cyclic olefin copolymer matrix in a specific, extremely low ratio. This achieves the effects of blocking leakage channels and improving the ultimate withstand voltage. The specific mechanism of action is as follows: Specifically, cyclic olefin copolymers are typically composed entirely of sp... 3The matrix consists of aliphatic saturated polymer segments composed of hybrid carbon, possessing a certain free volume and a typical amorphous continuous structure. When a suitable amount of small, rigid aromatic anthracene molecules enter and are uniformly dispersed in the gaps between these macromolecular segments through physical action, a homogeneous solid solution is formed. This process maintains the physical integrity of the matrix without destroying the original polymer backbone structure. Furthermore, considering that pure cyclic olefin copolymers are typical wide-bandgap insulators, and that anthracene molecules, due to their conjugated structure containing three fused benzene rings, possess high electron affinity, the lowest unoccupied molecular orbital energy level of anthracene is significantly lower than that of the cyclic olefin copolymer matrix. These dispersed anthracene molecules effectively introduce dense localized energy levels into the wide bandgap of the insulator, forming deep trap sites using the energy level difference. Under the coupling effect of high-temperature environments such as 150°C and high electric field stress, the intrinsic chain segment motion of the polymer matrix intensifies, and the injection of high-energy electrons from the electrode interface into the dielectric bulk phase significantly increases. When these free charge carriers attempt to jump and conduct within the polymer network, they are often captured and trapped by the densely distributed deep traps described above. The electrons, having lost their ability to migrate, sever the leakage current path through the bulk phase of the material at the physical transport level. This effectively suppresses the accumulation of Joule heat caused by continuous charge transport, thereby delaying the formation of electrical trees and the thermal breakdown process.

[0008] Preferably, the anthracene content in the raw material is 0.4 to 0.8 parts by weight; more preferably, the anthracene content is 0.4 parts by weight.

[0009] By employing the above technical solution and controlling the concentration distribution of the deep trap provider, the relationship between trap density and material homogeneity can be balanced. If the amount of anthracene added is too low, the effective trap density inside the matrix is ​​insufficient to cope with the injected charge under high field. After the traps saturate rapidly, the excess uncaptured charge carriers will still penetrate the material to form conductive channels. Conversely, if the amount added exceeds the upper limit of the above range, the excess anthracene molecules are prone to crystallization and aggregation, which will lead to micro-phase separation. This will disrupt the continuity of the polymer's amorphous framework, making the distorted electric field generated at the heterogeneous interface a leading channel for inducing breakdown. Using a ratio of 0.4 parts can provide sufficient trap trapping cross-section while ensuring a homogeneous dissolution state, thereby obtaining better high-temperature and high-pressure resistance performance on a macroscopic scale.

[0010] Preferably, the Fourier transform infrared spectrum of the cyclic olefin copolymer is at 2941 cm⁻¹. -1 and 2866cm -1 It has a CH stretching vibration peak at 1452 cm⁻¹. -1It exhibits a -CH2- bending vibration peak; its X-ray diffraction pattern shows an amorphous broadened and diffuse peak in the range of 2θ from 17° to 20°; the lowest unoccupied molecular orbital energy level of the cyclic olefin copolymer is -4.37 eV, and the highest occupied molecular orbital energy level is -9.76 eV; the anthracene is an aromatic compound with a three-fused benzene ring structure, with the molecular formula C. 14 H 10 The anthracene has a lowest unoccupied molecular orbital energy level of -5.24 eV and a highest occupied molecular orbital energy level of -8.11 eV; the difference between the lowest unoccupied molecular orbital energy levels of the anthracene and the cyclic olefin copolymer is 0.87 eV.

[0011] By employing the above technical solution, the structural and energy level matching relationships between the components were clarified. The pure aliphatic amorphous properties of the cycloolefin copolymer provide a fundamental high insulation and low polarization loss background. The 0.87 eV difference in the lowest unoccupied molecular orbital energy level between the matrix and anthracene constructs a suitable trap barrier depth. This deep trap can not only anchor high-energy carriers under an applied electric field, but also resist intrinsic thermal excitation perturbations caused by high-temperature environments to a certain extent, reducing the probability of trapped electrons undergoing secondary thermal detrapping, thereby improving the thermodynamic insulation stability of the organic amorphous material.

[0012] Preferably, at an ambient temperature of 150°C and a test frequency of 1000Hz, the dielectric constant of the composite dielectric film is between 2.31 and 2.37, and the dielectric loss is below 0.0010; at an ambient temperature of 150°C and a DC electric field of 200MV / m, the steady-state leakage current density of the composite dielectric film is less than 2.0 × 10⁻⁶. -6 A / cm 2 .

[0013] By adopting the above technical solutions, the thin film can maintain low dielectric polarization loss and conductivity dissipation under extreme high temperature conditions. This helps to reduce the heat generated by the material itself during charge and discharge cycles, thereby improving the energy conversion efficiency within the energy storage closed loop and maintaining the stable operation of the energy storage module.

[0014] Secondly, the present invention provides a method for preparing a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, employing the following technical solution: A method for preparing a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage includes the following steps: Weigh the cyclic olefin copolymer and the anthracene according to the specified ratio, add them together to an organic solvent, and dissolve them under heating and stirring conditions to obtain a homogeneous and transparent mixed solution. The resulting mixed solution was cast onto a clean substrate and then allowed to stand at room temperature. The sample after static treatment was placed in a vacuum drying equipment for high-temperature solvent removal and drying. After the sample is dried and cooled, the substrate with the sample attached is immersed in a stripping solution to remove the film. The film is then removed and dried to obtain the final product.

[0015] By employing the above-mentioned technical solution, the liquid-phase blending casting process alters the tendency for solid components to aggregate, allowing small-molecule anthracene to diffuse and miscibly disperse within the polymer solution system. During subsequent film formation and solvent removal, as the polymer macromolecular segments gradually converge and physically solidify, the anthracene molecules are in-situ encapsulated within the free volume at the junctions of the matrix macromolecular segments. This physical doping method eliminates the need for chemical modification of the polymer backbone and avoids the agglomeration problem common to conventional inorganic nanofillers. The overall process conditions are relatively mild, resulting in films with good uniformity.

[0016] Preferably, the organic solvent is xylene; the heating temperature is 110°C, the stirring speed is 200 r / min, and the dissolution time is 24 h; the substrate is a quartz plate; the standing treatment time at room temperature is 12 h; the temperature control parameters of the vacuum drying equipment are 150°C, and the drying time is 6 h; after the dried sample has naturally cooled to room temperature, the substrate with the sample attached is immersed in deionized water as a stripping solution, and after the film is detached, the film is removed and dried.

[0017] By employing the above technical solution, xylene exhibits good compatibility with both organic components. A temperature of 110℃ combined with mechanical stirring accelerates the thermal expansion of polymer chains and the mass transfer and diffusion of the solute, thus promoting the formation of a homogeneous solution. The room temperature settling process provides the cast film with sufficient leveling time to eliminate internal stress. Regarding the drying process, a vacuum environment at 150℃ helps remove residual high-boiling-point xylene solvent, preventing the residual solvent from acting as a plasticizer and reducing the material's high-temperature insulation performance. Finally, deionized water is used for liquid peeling, primarily utilizing the difference in surface tension and swelling characteristics at the interface between different phases to achieve autonomous film detachment. Compared to mechanical pulling, this reduces the generation of physical defects such as localized tensile damage or microcracks.

[0018] This invention provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. It offers the following advantages: 1. This invention involves physically doping a small amount of rigid aromatic anthracene molecules into the interstitial spaces of an amorphous network of a cyclic olefin copolymer, thereby constructing deep trap sites using the lowest unoccupied molecular orbital energy level difference between anthracene and the matrix. Under high temperature and high applied electric field conditions, these deep traps can capture free carriers injected at the electrode interface, restricting electron migration and thus blocking leakage current conduction paths within the bulk material. This mechanism reduces Joule heating generated during charge transport, thereby improving the voltage withstand capability and insulation reliability of the composite film under high temperature conditions.

[0019] 2. This invention employs a fully organic blending system, enabling molecular-level anthracene to form a homogeneous solid solution structure with a pure aliphatic amorphous cyclic olefin copolymer. This design avoids the particle agglomeration and localized electric field distortion at the phase interface problems commonly encountered when adding conventional inorganic nanofillers, maintaining the continuous amorphous framework of the polymer. Based on this, the composite film improves high-temperature and high-pressure resistance while maintaining the inherently low dielectric loss of the polymer matrix, helping to reduce self-heating and improve energy storage and conversion efficiency during operation.

[0020] 3. The preparation process of this invention utilizes conventional liquid-phase blending and casting techniques. As the solvent evaporates, the polymer chains converge and physically shape, encapsulating anthracene molecules in situ within the free volume of the matrix. This doping process does not require complex chemical grafting of the polymer backbone, and the overall operating conditions are mild, allowing for better control of the uniform dispersion of additives in the solution. This physical mixing-based film formation method is simple in procedure, and the prepared film exhibits a certain degree of thickness uniformity, making it more suitable for practical engineering and large-scale processing. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the band structure alignment and deep trap energy levels of the pure cyclic olefin copolymer and anthracene according to the present invention. Figure 2 The following is a trend graph showing the dielectric properties of the present invention at 150°C as a function of anthracene doping mass fraction, wherein (a) is a trend graph showing the dielectric constant as a function of anthracene doping mass fraction, and (b) is a trend graph showing the dielectric loss as a function of anthracene doping mass fraction. Figure 3 The graph shows the relationship between the steady-state leakage current density and the applied DC electric field strength at 150°C. Figure 4 The graphs show the trends of electrical insulation and energy storage performance of the present invention with the amount of anthracene added, where (a) is a graph showing the changes in characteristic breakdown field strength and Weibull shape parameters, and (b) is a graph showing the changes in discharge energy density and energy storage efficiency. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0023] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0024] The CAS number for the cyclic olefin copolymer is 26007-43-2. ​​This cyclic olefin copolymer is a polymer with an amorphous structure, and its Fourier transform infrared spectrum is at 2941 cm⁻¹. -1 and 2866cm -1 The place has sp 3 The CH stretching vibration peak of hybrid carbon is at 1452 cm⁻¹. -1 It has a -CH2- bending vibration peak, and its X-ray diffraction pattern shows an amorphous broadened diffuse peak in the range of 2θ from 17° to 20°. The lowest unoccupied molecular orbital energy level is -4.37 eV and the highest occupied molecular orbital energy level is -9.76 eV.

[0025] Anthracene has the CAS number 120-12-7. This substance is an aromatic hydrocarbon compound with a three-fused benzene ring structure, and its molecular formula is C2. 14 H 10 It exhibits sharp crystalline diffraction peaks, with its lowest unoccupied molecular orbital energy level being -5.24 eV and its highest occupied molecular orbital energy level being -8.11 eV.

[0026] Xylene's CAS number is 1330-20-7. This substance is a common organic solvent with the molecular formula C8H12H2O. 10 . Example 1:

[0027] This embodiment provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising the following steps: 1. Weigh a certain mass of cyclic olefin copolymer and add anthracene at a mass fraction of 0.4% relative to the cyclic olefin copolymer, and dissolve them together in xylene solvent; 2. Stir continuously for 24 hours at 110℃ and 200r / min to completely dissolve the mixture and form a homogeneous and transparent mixed solution; 3. The obtained mixed solution was cast onto a clean quartz plate and allowed to stand at room temperature for 12 hours. Then the cast sample was placed in a vacuum oven and dried at 150°C for 6 hours under vacuum. 4. After drying, allow the sample to cool naturally to room temperature. Immerse the quartz plate with the sample attached in deionized water to remove the film. After removing the film, dry it to obtain the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. Example 2:

[0028] This embodiment provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising the following steps: 1. Weigh a certain mass of cyclic olefin copolymer and add anthracene at a mass fraction of 0.2% relative to the cyclic olefin copolymer, and dissolve them together in xylene solvent; 2. Stir continuously for 24 hours at 110℃ and 200r / min to completely dissolve the mixture and form a homogeneous and transparent mixed solution; 3. The obtained mixed solution was cast onto a clean quartz plate and allowed to stand at room temperature for 12 hours. Then the cast sample was placed in a vacuum oven and dried at 150°C for 6 hours under vacuum. 4. After drying, allow the sample to cool naturally to room temperature. Immerse the quartz plate with the sample attached in deionized water to remove the film. After removing the film, dry it to obtain the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. Example 3:

[0029] This embodiment provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising the following steps: 1. Weigh a certain mass of cyclic olefin copolymer and add anthracene at a mass fraction of 0.6% relative to the cyclic olefin copolymer, and dissolve them together in xylene solvent; 2. Stir continuously for 24 hours at 110℃ and 200r / min to completely dissolve the mixture and form a homogeneous and transparent mixed solution; 3. The obtained mixed solution was cast onto a clean quartz plate and allowed to stand at room temperature for 12 hours. Then the cast sample was placed in a vacuum oven and dried at 150°C for 6 hours under vacuum. 4. After drying, allow the sample to cool naturally to room temperature. Immerse the quartz plate with the sample attached in deionized water to remove the film. After removing the film, dry it to obtain the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. Example 4:

[0030] This embodiment provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising the following steps: 1. Weigh a certain mass of cyclic olefin copolymer and add anthracene at a mass fraction of 0.8% relative to the cyclic olefin copolymer, and dissolve them together in xylene solvent; 2. Stir continuously for 24 hours at 110℃ and 200r / min to completely dissolve the mixture and form a homogeneous and transparent mixed solution; 3. The obtained mixed solution was cast onto a clean quartz plate and allowed to stand at room temperature for 12 hours. Then the cast sample was placed in a vacuum oven and dried at 150°C for 6 hours under vacuum. 4. After drying, allow the sample to cool naturally to room temperature. Immerse the quartz plate with the sample attached in deionized water to remove the film. After removing the film, dry it to obtain the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage. Example 5:

[0031] This embodiment provides a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, comprising the following steps: 1. Weigh a certain mass of cyclic olefin copolymer and add anthracene at a mass fraction of 1.0% relative to the cyclic olefin copolymer, and dissolve them together in xylene solvent; 2. Stir continuously for 24 hours at 110℃ and 200r / min to completely dissolve the mixture and form a homogeneous and transparent mixed solution; 3. The obtained mixed solution was cast onto a clean quartz plate and allowed to stand at room temperature for 12 hours. Then the cast sample was placed in a vacuum oven and dried at 150°C for 6 hours under vacuum. 4. After drying, allow the sample to cool naturally to room temperature. Immerse the quartz plate with the sample attached in deionized water to remove the film. After removing the film, dry it to obtain the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage.

[0032] Comparative Example 1: The difference from Example 1 is that the functional additive anthracene was not added, i.e., a pure cyclic olefin copolymer film was prepared; otherwise, they are the same.

[0033] Comparative Example 2: The difference from Example 1 is the addition of anthracene at a mass fraction of 3.0% relative to the cyclic olefin copolymer; all other aspects are the same.

[0034] Comparative Example 3: The difference from Example 1 is the addition of anthracene at a mass fraction of 0.05% relative to the cyclic olefin copolymer; all other aspects are the same.

[0035] Test Example 1: Determination of Band Structure and Deep Trap Level Parameters Experimental Description: This experiment uses ultraviolet photoelectron spectroscopy and ultraviolet-visible absorption spectroscopy to characterize the band structure of cyclic olefin copolymers and anthracene, obtaining their respective highest occupied molecular orbital energy levels and lowest unoccupied molecular orbital energy levels, thereby calculating the energy barrier difference and deep trap characteristics after the two are mixed.

[0036] Experimental steps: 1. Using quartz glass and glass with an indium tin oxide conductive layer as substrates, respectively, and xylene as solvent, pure cyclic olefin copolymer and anthracene were respectively prepared into solutions with a mass concentration of 10 mg / mL. The solutions were then spin-coated onto the substrate surface using a spin coater and dried in a vacuum oven for later use.

[0037] 2. Place the conductive glass substrate coated with the sample in the high-vacuum test chamber of the ultraviolet photoelectron spectrometer. Irradiate the sample with a helium lamp with an excitation energy of 21.22 eV as the excitation source. Apply a negative bias voltage to obtain the complete secondary electron cutoff edge. Record the photoelectron kinetic energy distribution curve and extract the cutoff edge intercept and the valence band oscillation point intercept. Calculate the highest occupied molecular orbital energy level of the material.

[0038] 3. Place the quartz substrate coated with the sample in a UV-Vis absorption spectrometer, using a blank quartz glass as a baseline reference, and perform absorption wavelength scanning in the spectral range of 200 nm to 800 nm, recording the curve of absorbance changing with wavelength.

[0039] 4. Based on the obtained absorption spectrum data, draw the Tauc diagram, perform extrapolation tangent processing on the linear region of the absorption edge, obtain the optical band gap value of the material, and combine it with the energy level parameters calculated in the previous ultraviolet photoelectron spectroscopy to calculate the lowest unoccupied molecular orbital energy level of each material.

[0040] The experimental data are shown in Table 1: Table 1: Band structure and spectral data of cyclic olefin copolymers and anthracene in conclusion: according to Figure 1 As shown in Table 1, the cyclic olefin copolymers and anthracene exhibit a regular difference in their basic physical band structures. During actual spectral scanning, it was observed that the cyclic olefin copolymers themselves are composed entirely of sp... 3The aliphatic saturated polymer network composed of hybrid carbon lacks pathways for electron delocalization transitions, resulting in a measured optical band gap of 5.39 eV. Based on the measured cutoff edge and oscillation point parameters, its HOMO level is calculated to be at an extremely low energy state of -9.76 eV, and the LUMO level is further calculated to be -4.37 eV. Anthracene, a small molecule of polycyclic aromatic hydrocarbons, contains a polycyclic conjugated π-electron structure, requiring relatively low energy for internal electron transitions, exhibiting an optical band gap of only 2.87 eV. The obtained HOMO and LUMO levels are -8.11 eV and -5.24 eV, respectively.

[0041] When considering the system state after these two substances are intertwined through solution blending, such intrinsic energy level data provides precise numerical support for microscopic physical effects. Since the LUMO level of anthracene is deeper than that of the cyclic olefin copolymer (specifically, the energy difference reaches 0.87 eV), this localized energy collapse constructs dense potential wells within the continuous amorphous polymer matrix. When the material is subjected to extreme conditions such as high-temperature thermal excitation at 150°C and strong DC electric field injection, a large number of freely moving charge carriers are inevitably excited internally. These low-energy regions in the gaps of the polymer network trap the passing charges due to the potential barrier difference. The disordered transport process of space charge is physically restricted here and loses its ability to migrate and conduct electricity. This deep trap anchoring mechanism fundamentally cuts off the possibility of Joule heating caused by localized current accumulation, constituting the mechanism basis for the composite thin film to suppress leakage current and prevent thermal breakdown.

[0042] Test Example 2: Wideband and Wide-Temperature Basic Dielectric Performance Test Experimental Description: This experiment uses a broadband dielectric spectrometer to scan and measure the dielectric constant and dielectric loss of thin film samples over a wide temperature range and a wide frequency range. The aim is to verify whether the physical blending strategy of low-concentration functional additives in the matrix will adversely interfere with the inherent low-loss electrical background of the material.

[0043] Experimental steps: 1. Select the thin film samples prepared in Examples 1 to 5 and Comparative Examples 1 to 3, cut them into circular samples with a diameter of 20 mm, and use an ion sputtering instrument to uniformly deposit a metal gold layer with a thickness of about 50 nm on both the top and bottom sides of the sample as a test electrode, ensuring that the electrode is in close contact with the material surface.

[0044] 2. Place the thin film sample with electrodes flat in the parallel plate temperature-controlled test fixture of the broadband dielectric spectrometer, apply a contact pressure of about 0.5N to eliminate the interference of the interfacial air gap on the low frequency signal acquisition, and then close and seal the test chamber.

[0045] 3. Set the temperature control program for the test chamber. The initial test temperature is 25℃. The temperature is gradually increased to the set maximum temperature of 175℃ at a heating rate of 2℃ / min. During this period, multiple temperature characteristic nodes are selected. When each temperature node is reached, the temperature is kept stable for 10 minutes to ensure the internal thermal balance of the sample. Then, the impedance analysis module is started.

[0046] 4. Within the set frequency range of 10 2 Hz to 10 6 An AC test bias voltage of 1V is applied to the sample within Hz. The instrument automatically collects the equivalent capacitance and loss tangent under different temperature and frequency cross conditions. The system software then calculates and outputs the dielectric constant and dielectric loss parameters of each material based on these values.

[0047] The experimental results are shown in Table 2; Table 2: Dielectric property test data of the examples and comparative examples at different temperatures and frequencies in conclusion: according to Figure 2 As shown in Table 2, the composite films covered in the examples exhibit highly stable dielectric responses over an extremely wide temperature range from room temperature to 175°C. In conventional polymer dielectric modification studies, it is often observed that the introduction of external additives, especially when the material is in a high-temperature range above 150°C, causes the Maxwell-Wagner polarization effect at the heterointerface to lead to an exponential increase in low-frequency dielectric loss. The measured data show that the cyclic olefin copolymer itself is entirely composed of nonpolar aliphatic carbon and lacks a permanent dipole moment, corresponding to Example 1 maintaining extremely low intrinsic losses across all frequency bands. When nonpolar polycyclic aromatic hydrocarbon anthracene with a relative mass fraction of 0.2% to 1.0% is incorporated into the polymer network through solution blending, the dielectric constants of Examples 1 to 5 fluctuate only within a small range of 2.31 to 2.37, and the dielectric loss at 150°C remains below 0.0010. This data distribution demonstrates that anthracene molecules are uniformly nested in a monomolecular state within the intersegments of amorphous chains, without inducing macroscopic phase separation or significant space charge polarization. Observation of Comparative Example 2 with high concentration of doping reveals that when the doping concentration reaches 3.0%, the dielectric loss at 150℃ and in the low-frequency range shows a significant increase, reaching 0.00482. This reflects that local microcrystalline aggregates begin to act as channels for conductivity loss percolation. The test results of the examples confirm from an engineering feasibility perspective that, relying on a homogeneous energy level modulation strategy with extremely low concentrations, physical doping can be achieved while preserving the extremely low dielectric loss characteristics of the substrate insulating base. This provides structural protection for the material to avoid thermal failure under extreme thermal fields, establishing the fundamental advantage of this pure organic blend system that does not generate additional heat dissipation at high temperatures.

[0048] Test Example 3: Comparative Test of Leakage Current Density under Extreme Operating Conditions at 150℃ Experimental Description: This experiment measures the bulk leakage current parameters of thin film materials under constant temperature and high electric field conditions, quantitatively analyzes the evolution of carrier transport behavior within the material with the applied field strength, and uses this to verify the actual capture efficiency of free charges by the local energy level construction in the composite system.

[0049] Experimental steps: 1. Obtain the thin film samples prepared in Examples 1 to 5 and Comparative Examples 1 to 3, cut them into uniform sizes, and use a mask to sputter 10 mm diameter circular foil gold electrodes on both sides of the sample.

[0050] 2. Place the processed thin film sample into the probe station test chamber equipped with a high and low temperature shielded box, adjust the temperature control system to raise the chamber environment to the set 150℃, and maintain this thermal equilibrium state for 30 minutes to fully eliminate the residual internal stress and interfacial stray charge of the material during the preparation and transfer process.

[0051] 3. Start the high-voltage DC power supply connected in series with the probe circuit, and apply a DC electric field to the sample starting from 0 and gradually increasing to 200MV / m with a specific gradient. Stay at each test voltage node for about 10 minutes until the transient displacement current and absorption current completely decay.

[0052] 4. After the loop current enters the stable conduction period, the absolute value of the steady-state current corresponding to each field strength node is read by the connected high-precision picoammeter. Combined with the effective conductive area of ​​the test electrode and the measured thickness of the sample, the steady-state leakage current density under a specific electric field stress is calculated.

[0053] The experimental results are shown in Table 3: Table 3: Steady-state leakage current density test data of the examples and comparative examples at 150°C. in conclusion: according to Figure 3 According to the data in Table 3, under the coupled stress of a high-temperature thermal field of 150℃ and a strong electric field of 200MV / m, the film of Comparative Example 1, without any doping modification, exhibited typical intrinsic high-temperature failure characteristics of polymers. In this extreme condition test, it was observed that the intensified thermal motion of molecular chain segments within the pure cyclic olefin copolymer significantly lowered the potential barrier for electron transitions, allowing a large amount of free charge injected by the electrode to easily penetrate the bulk insulator phase. Its steady-state leakage current density soared to 8.45 × 10⁻⁶ at 200MV / m. -6 A / cm 2This level of continuous carrier transport leads to the accumulation of extremely high Joule heat within the material. When we turn our attention to the embodiment based on energy level engineering, the leakage current evolution trajectory undergoes a fundamental shift. In particular, in the most optimized embodiment 1, even with an electric field strength increased to 200 MV / m, the leakage current density is still strongly suppressed to 1.82 × 10⁻⁶. -7 A / cm 2 The extremely low level of anthracene molecules, nearly two orders of magnitude lower than that of the pure substrate, directly reflects the crucial charge anchoring role played by the 0.87 eV deep trap energy level constructed by anthracene molecules in the wide bandgap of the polymer. High-energy electrons generated by thermal excitation are captured and deeply bound by these dense physical traps during hopping conduction, completely losing their ability to participate in macroscopic conductivity.

[0054] The relationship between additive concentration and trap binding effectiveness was further confirmed in the comparative data. In Comparative Example 3, the mass fraction of anthracene was only 0.05%, and its leakage current showed a nonlinear surge trend in the region above 150 MV / m electric field. This indicates that the limited trap energy level density in the matrix quickly reached saturation when dealing with the massive injected charge under a strong electric field, and the remaining uncaptured charge carriers could still penetrate the network to form leakage channels. In Comparative Example 2, excessive addition exposed another engineering defect. The doping of up to 3.0% not only failed to provide more effective traps, but also induced phase separation of the internal structure due to small molecule aggregation. The resulting distorted electric field at the phase interface caused the sample to experience electrical tree penetration breakdown before reaching the test endpoint of 200 MV / m. In the electrical testing of conventional polymer dielectric materials, sudden changes in leakage current are often regarded as a precursor to breakdown failure. Example 1, by precisely controlling the homogeneous doping ratio of 0.4%, maximized the trap trapping cross section while ensuring the integrity of the amorphous network of the matrix, successfully blocking the path of leakage to thermal breakdown at the physical transport level.

[0055] Test Example 4: Comparison Test of High-Temperature DC Breakdown Field Strength and High-Field Energy Storage Parameters Experimental Description: This experiment evaluates the ultimate withstand voltage and macroscopic energy storage characteristics of thin film samples at 150℃. The aim is to map the previously verified deep-trap charge trapping mechanism onto the core electrical parameters of practical engineering applications, and to establish the boundary of the role of energy level engineering in preventing high-temperature thermal breakdown failure of materials.

[0056] Experimental steps: 1. Select the prepared films of Examples 1 to 5 and Comparative Examples 1 to 3, and cut them into test samples of specific sizes. For energy storage charge and discharge tests, use a vacuum sputtering device to deposit circular gold electrodes with a diameter of 10 mm on both sides of the sample; for breakdown tests, wipe the surface of the sample without electrode plating with anhydrous ethanol to remove surface impurities.

[0057] 2. Place the breakdown sample to be tested in a constant temperature test system connected to a withstand voltage tester. The test medium is methyl silicone oil that has been preheated to 150°C and degassed to suppress surface flashover discharge that may occur during the application of a high electric field.

[0058] 3. Start the DC high voltage generator and apply a continuously increasing DC voltage to the sample at a fixed voltage increase rate of 500V / s until the material undergoes physical breakthrough breakdown. Record the breakdown voltage value at this point and convert it into breakdown field strength based on the sample thickness. Repeat the test 15 times for each batch of samples to obtain independent failure data. Calculate the characteristic breakdown field strength and shape parameters reflecting the uniformity of material defect distribution based on the Weibull distribution model.

[0059] 4. Connect the gold-plated sample to the ferroelectric polarization test platform equipped with a heating stage. After the sample temperature stabilizes at 150℃, apply a triangular wave alternating electric field at a frequency of 100Hz. Gradually increase the field strength amplitude to the maximum safe critical value that the material can withstand. The instrument automatically records the polarization-electric field hysteresis curves in each electric field cycle, and extracts the closed integral area of ​​the charging and discharging stages to calculate the corresponding discharge energy density and energy storage charging and discharging efficiency.

[0060] The experimental results are shown in Table 4: Table 4: Test data of breakdown field strength and high-field energy storage parameters of the examples and comparative examples at 150°C in conclusion: according to Figure 4 According to the test data in Table 4, the characteristic breakdown field strength of the undoped Comparative Example 1 at a thermal field of 150℃ is 535.4 MV / m. Due to the extremely low intrinsic polarization loss of the pure cyclic olefin copolymer, its energy storage efficiency can be maintained at 97.8% under a test electric field of 500 MV / m. However, under high temperature conditions, the expansion of the free volume inside the system and the thermal relaxation of the macromolecular chain segments are intensified. The pure aliphatic hydrocarbon skeleton is easily penetrated by free electrons injected under a high external electric field, which physically limits the ultimate withstand voltage and the upper limit of the energy storage density of the material.

[0061] For Example 1, when 0.4% by mass of anthracene was physically dissolved into the thin film network, the characteristic breakdown field strength of the material significantly increased to 603.2 MV / m, and the Weibull shape parameter, reflecting the uniformity of the microstructure, simultaneously reached 13.7. Under an applied electric field of 600 MV / m, close to the ultimate withstand voltage, the sample output 4.03 J / cm². 3The discharge energy density is high, and the charge-discharge efficiency within the energy storage closed loop remains at a high level of 94.2%. This structural evolution towards a pure organic homogeneous solid solution system indicates that the deep trap network constructed by small molecules effectively captures and confines space charge at the physical level, reducing continuous charge migration and Joule heat accumulation under high fields.

[0062] Observing the data changes caused by the doping gradient reveals that the macroscopic breakdown voltage performance of the material is directly affected by the evolution of its internal phase structure. In Comparative Example 3, the relatively low doping amount failed to create a sufficiently dense density of charge trapping sites within the matrix, allowing some charge carriers injected at high fields to still penetrate the dielectric bulk phase, resulting in a limited improvement in overall electrical performance. Conversely, in Comparative Example 2, the high doping amount of 3.0% significantly reduced its breakdown field strength to 450.5 MV / m, corresponding to a Weibull shape parameter of 7.8. This is because excessive anthracene molecules underwent microscopic crystallization and aggregation, disrupting the continuity of the polymer's amorphous framework. The distorted electric field generated at the heterojunction became the leading channel for breakdown.

[0063] Based on the aforementioned confirmation of the underlying microscopic mechanisms and macroscopic performance, this method avoids the complex steps of polymer backbone chemical modification and the interfacial defects caused by the easy aggregation of inorganic nanofillers by homogeneously dispersing small molecules in a specific ratio during the physical preparation process. This method utilizes molecular-level physical doping in a pure organic matrix to enhance high-temperature voltage withstand capability, effectively balancing high energy density and low dielectric dissipation, and provides a feasible technical path for improving the insulation stability of thin-film capacitors under harsh operating conditions.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, characterized in that, The composite dielectric film is made from raw materials comprising the following parts by weight: Cyclic olefin copolymer: 100 parts; Anthracene: 0.2–1.0 parts; Anthracene, acting as a deep trap provider, is uniformly dispersed in the amorphous network gaps of the cyclic olefin copolymer. By constructing deep trap sites through the fact that the lowest unoccupied molecular orbital energy level of anthracene is lower than that of the lowest unoccupied molecular orbital energy level of the cyclic olefin copolymer, the injected free carriers are captured under high temperature and strong electric field conditions, thereby suppressing leakage current inside the composite film and preventing thermal breakdown caused by Joule thermal accumulation.

2. The cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage according to claim 1, characterized in that, The cyclic olefin copolymer is an aliphatic saturated high molecular network consisting entirely of sp 3 hybridized carbon, whose Fourier transform infrared spectrum has C-H stretching vibration peaks at 2941 cm -1 and 2866 cm -1 -1, and -CH2- bending vibration peaks at 1452 cm -1 -1; and whose X-ray diffraction spectrum exhibits an amorphous broad diffuse peak in the range of 17° to 20° in 2θ.

3. The cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage according to claim 1, characterized in that, The lowest unoccupied molecular orbital energy level of the cyclic olefin copolymer is -4.37 eV, and the highest occupied molecular orbital energy level is -9.76 eV; The anthracene is an aromatic compound with three fused benzene rings and the molecular formula is C. 14 H 10 The lowest unoccupied molecular orbital energy level of the anthracene is -5.24 eV, and the highest occupied molecular orbital energy level is -8.11 eV.

4. The cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage according to claim 1, characterized in that, The energy difference between the lowest unoccupied molecular orbitals between the anthracene and the cyclic olefin copolymer is 0.87 eV, which constitutes the barrier collapse depth of the deep trap site.

5. The cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage according to claim 1, characterized in that, At an ambient temperature of 150℃ and 10 3 At a test frequency of Hz, the dielectric constant of the composite dielectric film is between 2.31 and 2.37, and the dielectric loss is below 0.0010. Under an ambient temperature of 150℃ and a DC electric field of 200MV / m, the steady-state leakage current density of the composite dielectric film is less than 2.0×10⁻⁶. -6 A / cm 2 .

6. A method for preparing a cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage, used to prepare the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh the cyclic olefin copolymer and the anthracene according to the ratio, add them together to an organic solvent, and dissolve them under heating and stirring conditions to obtain a homogeneous and transparent mixed solution. S2. Cast the mixed solution obtained in step S1 onto a clean substrate and then allow it to stand at room temperature. S3. Place the sample after the static treatment in step S2 into a vacuum drying equipment for high-temperature solvent removal and drying. S4. Cool the sample dried in step S3, then immerse the substrate with the sample attached in the stripping solution to remove the film. Take out the film and dry it to obtain the final product.

7. The method for preparing the cyclic olefin copolymer / anthracene composite dielectric thin film for high-temperature energy storage according to claim 6, characterized in that, In step S1, the organic solvent is xylene; the heating temperature is 110°C; the stirring speed is 200 r / min; and the dissolution time is 24 h.

8. The method for preparing the cyclic olefin copolymer / anthracene composite dielectric thin film for high-temperature energy storage according to claim 6, characterized in that, In step S2, the substrate is a quartz plate; the time for static treatment at room temperature is 12 hours.

9. The method for preparing the cyclic olefin copolymer / anthracene composite dielectric thin film for high-temperature energy storage according to claim 6, characterized in that, In step S3, the temperature control parameter of the vacuum drying equipment is 150℃, and the drying time is 6h.

10. The method for preparing the cyclic olefin copolymer / anthracene composite dielectric film for high-temperature energy storage according to claim 6, characterized in that, The specific implementation method of step S4 is as follows: after the dried sample has cooled naturally to room temperature, the substrate with the sample attached is immersed in deionized water as a stripping solution. After the film is detached, the film is taken out and dried.

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