High reliability aluminum electrolytic capacitor and method of making same

Abstract

The application discloses a high-reliability aluminum electrolytic capacitor and a preparation method thereof. The aluminum electrolytic capacitor comprises a core package and an electrolyte immersed in the core package. The electrolyte comprises, in terms of mass parts, 30-50 parts of an organic solvent, 10-20 parts of a composite lithium salt, 5-15 parts of an additive, and 0.05-0.15 parts of an electrolyte. The additive comprises 0.01-0.1 parts of oxazolidine and 0.48-0.51 parts of polyethylene glycol dimethyl ether. The application optimizes the electrolyte formula, introduces oxazolidine and polyethylene glycol dimethyl ether as key additives, and cooperates with the composite lithium salt, the organic solvent and the electrolyte, thereby significantly improving the anti-vibration performance and high-temperature load performance of the aluminum electrolytic capacitor. After the vibration test, the capacitance change rate can be controlled within ±0.2%. After the high-temperature load test, the capacitance attenuation amplitude is small, and the DF value and ESR remain stable. The application is particularly suitable for application scenarios with strict reliability requirements and has a wide market application prospect.

Description

Technical Field

[0001] This invention relates to the field of capacitor technology, and more specifically, to a high-reliability aluminum electrolytic capacitor and its manufacturing method. Background Technology

[0002] With the booming development of China's automotive industry, the automotive electronics industry has also entered a period of rapid growth. As a fundamental electronic component, capacitors are becoming increasingly important. However, due to the unique operating environment of automobiles, ordinary aluminum electrolytic capacitors have limitations under these stringent requirements. Therefore, with the rapid development of the new energy vehicle industry, the on-board charger (OBC), as a core component of the new energy vehicle charging system, directly affects the vehicle's charging efficiency, safety, and reliability. Aluminum electrolytic capacitors, as key electronic components in the OBC circuit, perform important functions such as filtering and energy storage, playing a crucial role in the overall performance of the OBC. Currently, aluminum electrolytic capacitors on the market for OBCs have some shortcomings, such as short service life and poor reliability under complex on-board conditions like high temperature and high ripple current, making it difficult to fully meet the increasingly demanding performance requirements of new energy vehicles. Compared with ordinary liquid aluminum electrolytic capacitors, on-board charger aluminum electrolytic capacitors have the characteristics of high reliability, long service life, vibration resistance, and tolerance to ultra-high ripple current. With the effective reduction in the cost of aluminum electrolytic capacitors, their application will become more and more widespread in the future, and the application prospects of the project products are very promising.

[0003] Chinese invention patent application CN117711826A discloses an electrolyte for an aluminum electrolytic capacitor, an aluminum electrolytic capacitor, and an on-board charger. The electrolyte comprises a β-carbon diol, an oxide film repair additive, a hydrogen scavenger, a solute, and the balance being a solvent. The hydrogen scavenger is one or more benzene ring-substituted derivatives of nitrobenzene, and the solute is a variety of saturated six-membered ring branched carboxylate salts. This technical solution can effectively meet the requirements for flashover voltage, solubility, and conductivity, increasing the flashover voltage to 500-650V and effectively ensuring solute decay. However, the above technical solution mainly focuses on improving the flashover voltage and hydrogen scavenging performance of the electrolyte to solve the electrochemical stability problem under ultra-high voltage conditions. However, during actual operation, the continuous vibrations generated by vehicle movement cause severe mechanical stress on aluminum electrolytic capacitors, leading to problems such as loosening of the capacitor core, uneven electrolyte distribution, increased equivalent series resistance (ESR), and capacitance decay. Simultaneously, the high-temperature environment generated by the on-board charger during prolonged operation accelerates the aging and decomposition of the electrolyte, resulting in electrolyte performance degradation, increased leakage current, and further capacitance reduction, ultimately affecting the reliability and lifespan of the OBC. Therefore, improving the vibration resistance and high-temperature load performance of aluminum electrolytic capacitors while ensuring the electrochemical performance of the electrolyte, so that they can maintain stable electrical performance under the complex vibration environment and high-temperature conditions of on-board vehicles, has become a pressing technical problem that needs to be solved.

[0004] Therefore, there is an urgent need to develop an aluminum electrolytic capacitor electrolyte and a corresponding aluminum electrolytic capacitor that combine excellent electrochemical performance, vibration resistance, and high-temperature load performance to meet the pressing demand for long-life components in high-reliability application scenarios (such as on-board chargers for new energy vehicles). Summary of the Invention

[0005] Therefore, it is necessary to address the above-mentioned technical problems by providing a high-reliability aluminum electrolytic capacitor and its preparation method.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a high-reliability aluminum electrolytic capacitor, comprising a core and an electrolyte impregnated in the core; The electrolyte comprises the following components by mass: Organic solvent: 30-50 parts; Composite lithium salt: 10-20 parts; Additives: 5-15 parts, wherein the additives include 0.01-0.1 parts of oxazolidine and 0.48-0.51 parts of polyethylene glycol dimethyl ether; Electrolytes: 0.05~0.15 parts.

[0007] Furthermore, the organic solvent comprises 32-34 parts of bis(fluoroethyl) carbonate, 21-22 parts of methyl-(2,2,2-trifluoroethyl) carbonate, 19.4-19.6 parts of diethyl carbonate, and 9.8-10 parts of γ-butyrolactone.

[0008] Furthermore, the composite lithium salt comprises 8.4 to 8.6 parts of lithium bis(fluorosulfonyl)imide and 3.4 to 3.5 parts of lithium bis(trifluoromethanesulfonyl)imide.

[0009] Furthermore, the additives also include 1.58-1.62 parts of vinylene carbonate, 0.87-0.93 parts of tris(trimethylsilyl)phosphate, 0.58-0.62 parts of fluorovinylene carbonate, and 0.38-0.42 parts of adiponitrile.

[0010] Furthermore, the electrolyte comprises 0.02 to 0.05 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.05 to 0.08 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0011] Furthermore, the core package includes an anode foil, a cathode foil, and electrolytic paper disposed between the anode foil and the cathode foil; The anode foil has a withstand voltage of 590~720V and a specific capacitance of 0.60~0.75μF / cm. 2 ; The specific capacitance of the cathode foil is 40~60 μF / cm³. 2 ; The density of the electrolytic paper is 0.6~0.9 g / cm³. 3 It has a thickness of 40~60μm and is composed of a mixture of polyester fiber and plant fiber.

[0012] A second aspect of this invention provides a method for preparing the high-reliability aluminum electrolytic capacitor as described in any one of the preceding claims, comprising the following steps: S1. Core package winding: The anode foil, cathode foil and electrolytic paper are wound together to form a core package; S2. Drying treatment: The core package is dried. S3. Electrolyte impregnation: The dried core package is impregnated in electrolyte to obtain an impregnated core package; S4. Dehydration treatment: The impregnated core package is dehydrated; S5, sectional waist trainer; S6. Aging treatment.

[0013] Furthermore, in step S3, the impregnation treatment adopts a cyclic vacuuming and pressurized impregnation method, cyclically applying negative and positive pressure; the impregnation treatment includes: first evacuating to -0.08~-0.10MPa and maintaining it for 5~10 minutes; then pressurizing to 0.4~0.6MPa and maintaining it for 10~15 minutes; repeating 3~5 times.

[0014] A third aspect of the present invention provides an on-board charger comprising the aluminum electrolytic capacitor described in any of the preceding claims.

[0015] The fourth aspect of this invention proposes the application of the high-reliability aluminum electrolytic capacitor described in any of the above claims in the preparation of on-board chargers for new energy vehicles.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a high-reliability aluminum electrolytic capacitor and its preparation method. By optimizing the electrolyte formulation and introducing oxazolidine and polyethylene glycol dimethyl ether as key additives under the synergistic effect of organic solvents, composite lithium salts, additives and electrolytes, the vibration resistance and high-temperature load performance of the aluminum electrolytic capacitor are improved. This avoids the problems of loosening of the core, uneven distribution of electrolyte, capacitance decay and aging decomposition of electrolyte and performance degradation caused by vibration under complex vehicle conditions of traditional aluminum electrolytic capacitors.

[0017] Regarding vibration performance, the electrolyte of this invention can effectively maintain the stability of the internal structure of the capacitor and the uniformity of electrolyte distribution, resulting in minimal capacitance change rate and stable DF value and ESR after sinusoidal vibration testing of aluminum electrolytic capacitors, thus exhibiting excellent vibration resistance. Regarding high-temperature load performance, the electrolyte formulation of this invention has good stability under high-temperature conditions, effectively maintaining the electrochemical performance of the capacitor, slowing down electrolyte aging and decomposition, and significantly extending the service life of the capacitor in high-temperature environments.

[0018] This invention is highly suitable for applications with stringent reliability requirements (such as on-board chargers for new energy vehicles), and can maintain stable electrical performance even under complex vibration environments and high-temperature conditions, thus having broad market application prospects. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 should fall within the scope of protection of the present invention.

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Example 1

[0021] This embodiment provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which includes the following steps: S1. Core winding: High-voltage and low-specific-capacitance anode and cathode foils are selected. The anode foil has a withstand voltage of 590~720V and a specific capacitance of 0.60~0.75μF / cm. 2 The specific capacitance of the cathode foil is 40~60 μF / cm³. 2 Specifically, the anode foil selected in this embodiment has a withstand voltage of 620V and a specific capacitance of 0.64μF / cm³. 2 The specific capacitance of the cathode foil is 50 μF / cm. 2 Low-density mixed fiber electrolytic paper is selected, with a density of 0.6~0.9 g / cm³. 3 The thickness is 40~60μm, and it is composed of a mixture of polyester fiber and plant fiber; specifically, the electrolytic paper used in this embodiment has a density of 0.8g / cm³. 3 The thickness is 50μm. Electrolytic paper is inserted between the anode foil and the cathode foil and wound into a core package.

[0022] S2. Drying treatment: The core package is dried.

[0023] S3. Electrolyte Impregnation: The core package treated in S2 is immersed in the electrolyte for impregnation. A cyclic vacuum and pressure impregnation method is used, cyclically applying negative and positive pressure to ensure the electrolyte fully impregnates the electrolytic paper, resulting in an impregnated core package. In this embodiment, the impregnation method is as follows: first, vacuum to -0.08~-0.10 MPa and maintain for 5~10 minutes; then, pressurize to 0.4~0.6 MPa and maintain for 10~15 minutes; repeat this cycle 3~5 times. Specifically, in this embodiment, vacuum to -0.09 MPa and maintain for 8 minutes; then pressurize to 0.5 MPa and maintain for 12 minutes; repeat 4 times.

[0024] The composition of the electrolyte is as follows: By weight, the organic solvents are: 32 parts bis(fluoroethyl) carbonate, 21 parts methyl-(2,2,2-trifluoroethyl) carbonate, 19.4 parts diethyl carbonate, and 9.8 parts γ-butyrolactone. Composite lithium salt: 8.4 parts lithium bis(fluorosulfonyl)imide and 3.4 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.58 parts vinylene carbonate, 0.88 parts tris(trimethylsilyl)phosphate, 0.58 parts fluorovinylene carbonate, and 0.38 parts adiponitrile; Electrolytes: 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate salt; it should be noted that the 1,2,3,4-tetramethylimidazolium benzoate anion used in this invention is not the same substance as 1,2,3,4-tetramethylimidazolium benzoate salt. The former (C 14 H 17 N2O2 - The benzoate anion (BSA) is an organic anion formed by the covalent linkage of a benzoate ion and a tetramethylimidazolium ring. It carries a single negative charge, exists in an ionic state, and is found only in solutions or ionic liquids. The salt (IMS) is a neutral ionic compound formed by the tetramethylimidazolium cation and the aforementioned anion through ionic bonds. It is a stable solid and serves as the carrier for the BSA. During preparation, the anion is added in solution form, while the salt is added directly in solid form. The salt dissociates in the solvent, releasing the same anion, and both act synergistically. The anion serves as a core functional unit: providing nitrogen and oxygen dual coordination sites for constructing metal-organic framework materials; regulating the solubility, thermal stability, and electrochemical window of the electrolyte; providing basic sites for catalytic reactions; and acting as a charge stabilizer to stabilize positively charged intermediates. The dissociated cations participate in ionic equilibrium and interfacial stability.

[0025] S4. Dehydration treatment: The impregnated core package is dehydrated; S5, waist-cinching assembly.

[0026] S6. Aging treatment.

[0027] The performance of the aluminum electrolytic capacitor prepared in this embodiment was tested using the following methods: (1) Initial electrical performance test: Under the condition of 25±3℃, the capacitance (CAP) and loss tangent (DF) were tested at a frequency of 120Hz using an LCR bridge tester, and the equivalent series resistance (ESR) was tested at a frequency of 100kHz; the leakage current (LC) was tested under the condition of applying rated voltage for 120s.

[0028] (2) Vibration test: Vibration was performed for 2 hours on each of the X, Y, and Z axes in the frequency range of 10~2000Hz, with an acceleration of 30g and a logarithmic sweep frequency. The capacitance change rate (ΔC / C), DF, ESR, and LC were recorded before and after the vibration.

[0029] (3) High temperature load test: Apply the rated voltage to the capacitor at 105℃ and continue the test for 1000 hours. Record the capacitance change rate (△C / C), DF, ESR and LC before and after the test.

[0030] The test results are shown in Tables 1 and 2. The test methods for subsequent embodiments and comparative examples are the same as those for this embodiment, and will not be described again.

[0031] Table 1. Vibration test performance results of Example 1 Table 2. Performance test results of high temperature load test in Example 1 Example 2

[0032] This embodiment provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Embodiment 1 in that the electrolyte formulation is different. Specifically, in this embodiment, the component ratio of the electrolyte is as follows: By weight, the organic solvents are: 32 parts bis(fluoroethyl) carbonate, 21 parts methyl-(2,2,2-trifluoroethyl) carbonate, 19.4 parts diethyl carbonate, and 9.8 parts γ-butyrolactone. Composite lithium salt: 8.4 parts lithium bis(fluorosulfonyl)imide and 3.4 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.58 parts of vinylene carbonate, 0.88 parts of tris(trimethylsilyl)phosphate, 0.58 parts of fluorovinylene carbonate, 0.38 parts of adiponitrile, and 0.05 parts of oxazolidine; Electrolytes: 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0033] The remaining steps are the same as in Example 1.

[0034] The performance of the aluminum electrolytic capacitor prepared in this embodiment was tested using the same method as in Embodiment 1. The results are shown in Tables 3 and 4.

[0035] Table 3. Vibration test performance results of Example 2 Table 4. Performance test results of high temperature load test in Example 2 Example 3

[0036] This embodiment provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Embodiment 1 in that the electrolyte formulation is different. The component ratio of the electrolyte is as follows: By weight, the organic solvents are: 32-34 parts of bis(fluoroethyl) carbonate, 21-22 parts of methyl-(2,2,2-trifluoroethyl) carbonate, 19.4-19.6 parts of diethyl carbonate, and 9.8-10 parts of γ-butyrolactone. Composite lithium salt: 8.4~8.6 parts of lithium bis(fluorosulfonyl)imide and 3.4~3.5 parts of lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.58-1.62 parts of vinylene carbonate, 0.87-0.93 parts of tris(trimethylsilyl)phosphate, 0.58-0.62 parts of fluorovinylene carbonate, 0.38-0.42 parts of adiponitrile, 0.01-0.1 parts of oxazolidine, and 0.48-0.51 parts of polyethylene glycol dimethyl ether; Electrolytes: 0.02~0.05 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.05~0.08 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0037] The specific formulation used in this embodiment is as follows (by weight): 33 parts of bis(fluoroethyl) carbonate, 21.5 parts of methyl-(2,2,2-trifluoroethyl) carbonate, 19.5 parts of diethyl carbonate, and 9.9 parts of γ-butyrolactone; 8.5 parts of lithium bis(fluorosulfonyl)imide, and 3.45 parts of lithium bis(trifluoromethanesulfonyl)imide; 1.60 parts of vinylene carbonate, 0.90 parts of tris(trimethylsilyl) phosphate, 0.60 parts of fluorovinylene carbonate, 0.40 parts of adiponitrile, 0.05 parts of oxazolidine, 0.50 parts of polyethylene glycol dimethyl ether, 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion, and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate.

[0038] The remaining steps are the same as in Example 1.

[0039] The performance of the aluminum electrolytic capacitor prepared in this embodiment was tested using the same method as in Embodiment 1. The results are shown in Tables 5 and 6.

[0040] Table 5. Vibration test performance results of Example 3 Table 6. Performance test results of high temperature load test in Example 3 Example 4

[0041] This embodiment provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Embodiment 3 in the proportions of the components in the electrolyte formulation. Specifically, in this embodiment, the component ratios of the electrolyte are as follows: By weight, the organic solvents are: 32 parts bis(fluoroethyl) carbonate, 21 parts methyl-(2,2,2-trifluoroethyl) carbonate, 19.4 parts diethyl carbonate, and 9.8 parts γ-butyrolactone. Composite lithium salt: 8.4 parts lithium bis(fluorosulfonyl)imide and 3.4 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.58 parts of vinylene carbonate, 0.87 parts of tris(trimethylsilyl)phosphate, 0.58 parts of fluorovinylene carbonate, 0.38 parts of adiponitrile, 0.01 parts of oxazolidine, and 0.48 parts of polyethylene glycol dimethyl ether; Electrolytes: 0.02 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.05 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0042] The remaining steps are the same as in Example 3.

[0043] The performance of the aluminum electrolytic capacitor prepared in this embodiment was tested using the same method as in Embodiment 1. The results are shown in Tables 7 and 8.

[0044] Table 7. Vibration test performance results of Example 4 Table 8. Performance test results of high temperature load test in Example 4 Example 5

[0045] This embodiment provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Embodiment 1 in that the electrolyte formulation is different. Specifically, in this embodiment, the component ratio of the electrolyte is as follows: By weight, the organic solvents are: 34 parts bis(fluoroethyl) carbonate, 22 parts methyl-(2,2,2-trifluoroethyl) carbonate, 19.6 parts diethyl carbonate, and 10.0 parts γ-butyrolactone. Composite lithium salt: 8.6 parts lithium bis(fluorosulfonyl)imide and 3.5 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.62 parts vinylene carbonate, 0.93 parts tris(trimethylsilyl)phosphate, 0.62 parts fluorovinylene carbonate, 0.42 parts adiponitrile, 0.1 parts oxazolidine, 0.51 parts polyethylene glycol dimethyl ether. Electrolytes: 0.05 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.08 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0046] The remaining steps are the same as in Example 1.

[0047] The performance of the aluminum electrolytic capacitor prepared in this embodiment was tested using the same method as in Embodiment 1. The results are shown in Tables 9 and 10.

[0048] Table 9. Vibration test performance results of Example 5 Table 10. Performance test results of high temperature load test in Example 5 The test results of Examples 1-5 show that the present invention significantly improves the vibration resistance and high-temperature load performance of aluminum electrolytic capacitors by optimizing the electrolyte formulation, especially by introducing oxazolidine and polyethylene glycol dimethyl ether as key additives.

[0049] Regarding vibration resistance: In Example 1, without the addition of the two components mentioned above, the capacitance after vibration was large, and the DF value and ESR increased significantly; In Example 2, with only the addition of oxazolidine, the capacitance change rate after vibration improved to about -5%, but there was still significant fluctuation; In Examples 3-5, with the simultaneous addition of oxazolidine and polyethylene glycol dimethyl ether, and with the ratio optimized to the range of this invention, the capacitance change rate after vibration could be controlled within ±0.2%, while the DF value and ESR remained basically unchanged, demonstrating excellent vibration resistance stability.

[0050] Regarding high-temperature load performance: In Example 1, the capacitance decay exceeded 10% after high-temperature load, and the DF value and ESR deteriorated significantly; in Example 2, the capacitance decay still reached more than 7% after high-temperature load; while in Examples 3-5, the capacitance change rate was controlled at around -5% after high-temperature load, and the increase in DF value and ESR was significantly reduced. This indicates that the synergistic effect of oxazolidine and polyethylene glycol dimethyl ether effectively inhibited the aging and decomposition of the electrolyte at high temperatures, and significantly improved the high-temperature durability performance of the capacitor.

[0051] The above results indicate that the synergistic effect of oxazolidine and polyethylene glycol dimethyl ether is the key to achieving the excellent vibration resistance and high-temperature load performance of this invention.

[0052] Comparative Example 1 This comparative example provides a method for preparing an aluminum electrolytic capacitor for an on-board charger. The difference between this method and Example 1 lies in the electrolyte formulation, and the absence of oxazolidine and polyethylene glycol dimethyl ether. In this comparative example, the electrolyte composition is as follows: By weight, the organic solvents are: 28 parts bis(fluoroethyl) carbonate, 23.5 parts methyl-(2,2,2-trifluoroethyl) carbonate, 23.5 parts diethyl carbonate, and 9.5 parts γ-butyrolactone. Composite lithium salt: 8.5 parts lithium bis(fluorosulfonyl)imide and 4.0 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.4 parts vinylene carbonate, 0.75 parts tris(trimethylsilyl)phosphate, 0.5 parts fluorovinylene carbonate, and 0.4 parts adiponitrile; Electrolytes: 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0053] The remaining steps are the same as in Example 1.

[0054] The performance of the aluminum electrolytic capacitor prepared in this comparative example was tested using the same method as in Example 1. The results are shown in Tables 11 and 12.

[0055] Table 11. Vibration test performance results of Comparative Example 1 Table 12. Performance test results of high temperature load test in Comparative Example 1 Comparative Example 2 This comparative example provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Comparative Example 1 in that 0.05 parts of oxazolidine are added. In this comparative example, the composition ratio of the electrolyte is: By weight, the organic solvents are: 28 parts bis(fluoroethyl) carbonate, 23.5 parts methyl-(2,2,2-trifluoroethyl) carbonate, 23.5 parts diethyl carbonate, and 9.5 parts γ-butyrolactone. Composite lithium salt: 8.5 parts lithium bis(fluorosulfonyl)imide and 4.0 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.4 parts vinylene carbonate, 0.75 parts tris(trimethylsilyl)phosphate, 0.5 parts fluorovinylene carbonate, 0.4 parts adiponitrile, 0.05 parts oxazolidine; Electrolytes: 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0056] The remaining steps are the same as in Example 1.

[0057] The performance of the aluminum electrolytic capacitor prepared in this comparative example was tested using the same method as in Example 1. The results are shown in Tables 13 and 14.

[0058] Table 13. Vibration test performance results of Comparative Example 2 Table 14. Performance test results of high temperature load test in Comparative Example 2 Comparative Example 3 This comparative example provides a method for preparing an aluminum electrolytic capacitor for an on-board charger, which differs from Comparative Example 1 in that it adds 0.05 parts of oxazolidine and 0.50 parts of polyethylene glycol dimethyl ether. In this comparative example, the composition ratio of the electrolyte is as follows: By weight, the organic solvents are: 28 parts bis(fluoroethyl) carbonate, 23.5 parts methyl-(2,2,2-trifluoroethyl) carbonate, 23.5 parts diethyl carbonate, and 9.5 parts γ-butyrolactone. Composite lithium salt: 8.5 parts lithium bis(fluorosulfonyl)imide and 4.0 parts lithium bis(trifluoromethanesulfonyl)imide; Additives: 1.4 parts vinylene carbonate, 0.75 parts tris(trimethylsilyl)phosphate, 0.5 parts fluorovinylene carbonate, 0.4 parts adiponitrile, 0.05 parts oxazolidine, and 0.50 parts polyethylene glycol dimethyl ether; Electrolytes: 0.035 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.065 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

[0059] The remaining steps are the same as in Example 1.

[0060] The performance of the aluminum electrolytic capacitor prepared in this comparative example was tested using the same method as in Example 1. The results are shown in Tables 15 and 16.

[0061] Table 15. Vibration test performance results of Comparative Example 3 Table 16. Performance test results of high temperature load test for Comparative Example 3 The test results of Comparative Examples 1-3 show that although adding oxazolidine and polyethylene glycol dimethyl ether to the original formula can improve the vibration resistance and high temperature load performance, the effect is far less than that of Examples 3-5.

[0062] Regarding vibration resistance: In Comparative Example 1, without the addition of either ingredient, the capacitance decayed severely after vibration, with a change rate as high as approximately -40% to -43%, the DF value rose to over 27%, and the ESR surged; In Comparative Example 2, with only the addition of oxazolidine, the capacitance change rate after vibration improved to approximately -17% to -18%, but significant decay still occurred; In Comparative Example 3, with the addition of both ingredients, the capacitance change rate after vibration was further reduced to approximately -10% to -11%. In contrast, Examples 3-5, by optimizing the basic ratio and adding both ingredients, achieved a capacitance change rate after vibration controlled within ±0.2%, far superior to the comparative examples.

[0063] Regarding high-temperature load performance: Comparative Example 1 showed a capacitance decrease of approximately -18% after high-temperature load, with the DF value rising to over 26% and a significant deterioration in ESR; Comparative Example 2 showed a capacitance decrease of approximately -15% to -16% after high-temperature load, with the DF value still above 20%; Comparative Example 3 showed a capacitance decrease of approximately -12% after high-temperature load, with the DF value still above 15%. In contrast, Examples 3-5 showed a capacitance change rate controlled at around -5% after high-temperature load, with the DF value only rising to around 6%, far superior to the comparative examples.

[0064] The above comparison results show that the synergistic effect of oxazolidine and polyethylene glycol dimethyl ether needs to be fully utilized in combination with the overall optimization of the basic ratio. Simply adding these two components to the comparative formulation cannot achieve the excellent vibration resistance and high temperature load performance described in this invention.

[0065] Obviously, the embodiments described above are merely some embodiments of this application, not all embodiments, and do not limit the patent scope of this application. This application can be implemented in many different forms; on the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this application.

Claims

1. A high-reliability aluminum electrolytic capacitor, characterized in that, Includes a core package and an electrolyte impregnated in the core package; The electrolyte comprises the following components by mass: Organic solvent: 30-50 parts; Composite lithium salt: 10-20 parts; Additives: 5-15 parts, wherein the additives include 0.01-0.1 parts of oxazolidine and 0.48-0.51 parts of polyethylene glycol dimethyl ether; Electrolytes: 0.05~0.15 parts.

2. The high-reliability aluminum electrolytic capacitor according to claim 1, characterized in that, The organic solvent comprises 32-34 parts of bis(fluoroethyl) carbonate, 21-22 parts of methyl-(2,2,2-trifluoroethyl) carbonate, 19.4-19.6 parts of diethyl carbonate, and 9.8-10 parts of γ-butyrolactone.

3. The high-reliability aluminum electrolytic capacitor according to claim 1, characterized in that, The composite lithium salt comprises 8.4 to 8.6 parts of lithium bis(fluorosulfonyl)imide and 3.4 to 3.5 parts of lithium bis(trifluoromethanesulfonyl)imide.

4. The high-reliability aluminum electrolytic capacitor according to claim 1, characterized in that, The additives also include 1.58-1.62 parts of vinylene carbonate, 0.87-0.93 parts of tris(trimethylsilyl)phosphate, 0.58-0.62 parts of fluorovinylene carbonate, and 0.38-0.42 parts of adiponitrile.

5. The high-reliability aluminum electrolytic capacitor according to claim 1, characterized in that, The electrolyte comprises 0.02 to 0.05 parts of 1,2,3,4-tetramethylimidazolium benzoate anion and 0.05 to 0.08 parts of 1,2,3,4-tetramethylimidazolium benzoate salt.

6. The high-reliability aluminum electrolytic capacitor according to claim 1, characterized in that, The core package includes an anode foil, a cathode foil, and electrolytic paper disposed between the anode foil and the cathode foil; The anode foil has a withstand voltage of 590~720V and a specific capacitance of 0.60~0.75μF / cm. 2 ; The specific capacitance of the cathode foil is 40~60 μF / cm³. 2 ; The density of the electrolytic paper is 0.6~0.9 g / cm³. 3 It has a thickness of 40~60μm and is composed of a mixture of polyester fiber and plant fiber.

7. A method for preparing a high-reliability aluminum electrolytic capacitor as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Core package winding: The anode foil, cathode foil and electrolytic paper are wound together to form a core package; S2. Drying treatment: The core package is dried. S3. Electrolyte impregnation: The dried core package is impregnated in electrolyte to obtain an impregnated core package; S4. Dehydration treatment: The impregnated core package is dehydrated; S5, sectional waist trainer; S6. Aging treatment.

8. The preparation method according to claim 7, characterized in that, In step S3, the impregnation treatment adopts a cyclic vacuuming and pressurized impregnation method, cyclically applying negative and positive pressure; the impregnation treatment includes: first evacuating to -0.08~-0.10MPa and maintaining it for 5~10 minutes; then pressurizing to 0.4~0.6MPa and maintaining it for 10~15 minutes; repeating 3~5 times.

9. An on-board charger, characterized in that, It includes the aluminum electrolytic capacitor as described in any one of claims 1 to 6.

10. The application of the high-reliability aluminum electrolytic capacitor according to any one of claims 1 to 6 in the preparation of on-board chargers for new energy vehicles.

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