An electrolytic capacitor

Abstract

This invention relates to the field of electrochemical technology, specifically to an electrolytic capacitor, comprising a capacitor element, a solid electrolyte, and an additive, wherein the additive is R1 (COOCO). m The compound shown in the structural formula, wherein R1 is a substituted or unsubstituted saturated or unsaturated hydrocarbon group, and m is an integer greater than or equal to 1. The electrolytic capacitor of the present invention contains R1 (COOCO). m The compound shown in the structural formula can react with water to absorb moisture, and the acid produced after the reaction can also improve the stability of the electrolyte, reduce or eliminate the moisture that is already present in the capacitor or that enters during use, effectively reduce the sensitivity of electrolytic capacitors to moisture during use, and extend the service life of the capacitor, especially in high temperature and high humidity environments.

Description

Technical Field

[0001] The present invention relates to the field of electrochemistry technology, and particularly relates to an electrolytic capacitor. Background Art

[0002] Compared with ordinary electrolytic capacitors, solid electrolytic capacitors use solid conductive materials with high conductivity and good thermal stability as electrolytes. They not only have all the characteristics of ordinary electrolytic capacitors, but also have characteristics such as high reliability, long service life, low impedance at high frequencies, and resistance to extremely large ripple currents. In recent years, with the development trend of integration, miniaturization, and lightweight of electronic products, higher requirements are put forward for the performance of capacitors. The main technical development trends are: high temperature resistance, high efficiency, chip type, and laminated type. Correspondingly, the high reliability of capacitors is becoming more and more important. However, currently, with the long-term use of capacitors, due to reasons such as the performance of the capacitors themselves, they are prone to aging in high-temperature and high-humidity environments, reducing the service life of the capacitors.

[0003] In the prior art, for solid electrolytic capacitors, in order to help protect the capacitors from the influence of the external environment and provide good mechanical stability for them, epoxy resin is usually used for encapsulation. However, when there is a high level of moisture in the surrounding environment, it will cause the epoxy resin to slowly damage or degrade, allowing a small amount of moisture to penetrate into the interior of the capacitor, resulting in a rapid deterioration of the electrical performance of the capacitor. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an electrolytic capacitor, which effectively extends the service life of the capacitor in high-temperature and high-humidity environments through the use of additives.

[0005] The present invention adopts the following technical solutions:

[0006] An electrolytic capacitor includes a capacitor element, a solid electrolyte, and an additive. The capacitor element includes an anode foil, a cathode foil, and a separator with a dielectric layer on the surface. The solid electrolyte includes a conductive polymer, and the additive is a compound shown in the following formula I:

[0007] Formula I: R1(COOCO)

[0010] ,

[0009] , ,

[0008] ,

[0008] Where R1 is a substituted or unsubstituted saturated or unsaturated hydrocarbon group, and m is an integer greater than or equal to 1.

[0009] Further, based on the total mass of the capacitor element being 100%, the mass percentage content of the additive is A, satisfying 0 < A ≤ 80%. Preferably, it satisfies 10% ≤ A ≤ 50%.

[0010] Furthermore, the boiling point of the additive is higher than 120°C, and the boiling point of the product reacting with water is higher than 120°C. Preferably, the boiling point of the additive is higher than 200°C, and the boiling point of the product reacting with water is higher than 200°C. The high boiling point of the additive ensures that the internal pressure of the capacitor will not be excessive due to the phase change of the additive under high-temperature conditions, thus affecting the capacitor's sealing performance. Specifically, the additive is selected from one or more of phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride glycerol, polyazelite anhydride, polysaccharide anhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxobisphthalic anhydride, bisphenol A type diether dianhydride, pyromellitic anhydride, hexafluorodianhydride, and benzophenone tetracarboxylic dianhydride.

[0011] Furthermore, the conductive polymer is polythiophene or a polythiophene derivative.

[0012] The electrolytic capacitor of this invention uses R1 (COOCO). m The compound shown in the structural formula, as an additive, can reduce or eliminate the moisture present in the capacitor itself and the moisture that enters during use, effectively preventing the decrease in conductivity caused by the dedoping reaction of the conductive polymer in the capacitor. At the same time, the acid generated by the reaction of the additive with water can act as a dopant to react with the conductive polymer, giving the conductive polymer a self-healing function, thereby extending the service life of the capacitor, especially extending the service life of the capacitor in high temperature and high humidity environments. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments thereof. 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 protection scope of the present invention.

[0014] The capacitor provided by this invention can be manufactured using the following method:

[0015] S1. Cut the anode foil, cathode foil, and diaphragm to the specified width, and attach guide pins to the anode foil and cathode foil respectively;

[0016] S2. The anode foil, cathode foil and diaphragm after step S1 are stacked and wound into a capacitor element, and the core is welded onto the iron strip;

[0017] S3. Immerse the above-mentioned capacitor elements in a chemical formation solution for chemical formation treatment and then dry them;

[0018] S4. The capacitor element after step S3 is immersed in a conductive polymer dispersion for impregnation treatment.

[0019] S5. After the impregnation treatment is completed, the capacitor elements are dried.

[0020] S6. The capacitor element, which has formed a solid electrolyte after step S5, and the additives are placed in an aluminum shell and then sealed with a rubber stopper.

[0021] Examples 1-6 and Comparative Example 1

[0022] A 47uf-25v capacitor was designed and manufactured using the method described above by adding the additives shown in Table 1. The initial electrical performance parameters of the capacitor were then tested, as well as the electrical performance parameters after storage at 85°C and 85% RH for 1 hour. The results are shown in Table 2.

[0023] Table 1

[0024]

[0025] Table 2

[0026]

[0027]

[0028]

[0029] As can be seen from the comparison of Examples 1-6 and Comparative Example 1 in Table 2, after the double 85 (85℃, 85RH%, high temperature and high humidity) test, the capacitors with additives in Examples 1-6 showed significantly less electrical performance degradation than the capacitors without additives in Comparative Example 1. In Comparative Example 1, the conductivity of the capacitor decreased due to the dedoping of the conductive polymer, which led to a decrease in the capacitor's capacitance and a sharp increase in the equivalent series resistance.

[0030] Examples 7-12

[0031] A 47uf-25v capacitor was designed and manufactured using the method described above by adding the additives shown in Table 3. The initial electrical performance parameters of the capacitor were then tested, as well as the electrical performance parameters after storage at 85°C and 85% RH for 1 hour. The results are shown in Table 4.

[0032] Table 3

[0033]

[0034] Table 4

[0035]

[0036]

[0037] As shown in Table 4, with the increase of additive content, within a range not exceeding 80%, the capacitance and equivalent series resistance stability of the capacitors increased after the high temperature and high humidity storage test, that is, the resistance to high temperature and high humidity gradually improved. However, excessive additive content can also lead to a certain degree of degradation of the initial electrical performance parameters of the capacitor. This may be because these additives are mainly non-conductive substances, and when the amount added exceeds a certain level, the electrical performance of the capacitor will decrease.

[0038] The electrolytic capacitor of this invention uses R1 (COOCO). m The compound shown in the structural formula, as an additive, can reduce or eliminate the moisture present in the capacitor itself and the moisture that enters during use, effectively preventing the conductor polymer in the capacitor from undergoing a dedoping reaction that causes a decrease in conductivity. At the same time, the acid generated by the reaction of the additive with water can act as a dopant to react with the conductor polymer, giving the conductor polymer a self-healing function, thereby extending the service life of the capacitor, especially extending the service life of the capacitor in high temperature and high humidity environments.

[0039] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. An electrolytic capacitor, characterized by, The device includes a capacitor element, a solid electrolyte, an additive, an aluminum casing, and a rubber stopper for sealing the aluminum casing. The capacitor element and the additive are housed within the aluminum casing. The capacitor element includes an anode foil, a cathode foil, and a separator, all having dielectric layers on their surfaces. The solid electrolyte comprises a conductive polymer. The additive is a compound represented by Formula I. Formula I: R1(COOCO) m Where R1 is a substituted or unsubstituted saturated or unsaturated hydrocarbon group, and m is an integer greater than or equal to 1.

2. The electrolytic capacitor according to claim 1, characterized in that, With the total mass of the capacitor elements being 100%, the mass percentage of the additive is A, satisfying 0. <A≤80%。 3. The electrolytic capacitor according to claim 1, characterized in that, The additive has a boiling point higher than 120°C, and the product obtained by reacting with water has a boiling point higher than 120°C.

4. The electrolytic capacitor according to any one of claims 1-3, characterized in that, The additive is selected from one or more of the following: phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride glyceride, polyazelic anhydride, polysaccharide anhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxobisphthalic anhydride, bisphenol A type diether dianhydride, pyromellitic anhydride, hexafluorodianhydride, and benzophenone tetracarboxylic dianhydride.

5. The electrolytic capacitor according to claim 1, characterized in that, The conductive polymer is polythiophene or a polythiophene derivative.

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