A method for preparing a high temperature resistant poly 3,4-ethylenedioxythiophene chip-type laminated aluminum electrolytic capacitor

Abstract

The invention relates to the technical field of capacitor preparation, in particular to a method for preparing a high-temperature resistant poly (3,4-ethylenedioxythiophene) sheet-type laminated aluminum electrolytic capacitor, comprising aluminum foil treatment, chemical polymerization, electrochemical polymerization, coating a carbon-containing conductive layer, coating a silver-containing conductive layer, lamination bonding, epoxy resin encapsulation and aging. In the process of chemical polymerization and electrochemical polymerization, a polysulfonic acid with a large molecular weight and a high melting point is introduced as a dopant and a cross-linking agent, and cross-linking between poly (3,4-ethylenedioxythiophene) molecular chains is achieved through the interaction between sulfonic acid radicals and positively charged poly (3,4-ethylenedioxythiophene) molecular chains, thereby improving the thermal stability of poly (3,4-ethylenedioxythiophene) molecular chains, and further obtaining poly (3,4-ethylenedioxythiophene) with a regular structure and high temperature resistance, so that the prepared aluminum electrolytic capacitor has the advantages of low leakage current, small equivalent series resistance, stable capacitance and the like when used for a long time in a high-temperature environment.

Description

Technical Field

[0001] The invention relates to the technical field of capacitor preparation, in particular to a method for preparing a high-temperature resistant poly 3,4-ethylenedioxythiophene sheet-type laminated aluminum electrolytic capacitor. Background Art

[0002] Poly (3,4-ethylenedioxythiophene) is a commonly used conductive polymer with many advantages, including high conductivity, excellent optical properties, high stability, easy processability, and environmental protection. It can be widely used in the preparation of electronic components in various fields such as flexible electronic devices, organic optoelectronic devices, sensors, and energy storage devices, and has broad application prospects in the field of electronics.

[0003] However, the poly(3,4-ethylenedioxythiophene) molecular chain is a linear structure, which will be oxidized when used in a high temperature environment, resulting in molecular chain breakage and degradation. When used for a long time in a high temperature environment, the poly(3,4-ethylenedioxythiophene) chip-type laminated aluminum electrolytic capacitor will be affected, resulting in changes in its performance, including decreased conductivity and capacity, which will in turn affect the performance and stability of the capacitor and shorten its service life. Therefore, improving the comprehensive performance of the poly(3,4-ethylenedioxythiophene) chip-type laminated aluminum electrolytic capacitor used in a high temperature environment can meet its application and development trend in the field of electronic materials. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type laminated aluminum electrolytic capacitor, so that the prepared aluminum electrolytic capacitor has the advantages of low leakage current, small equivalent series resistance, stable capacitance, etc. when used for a long time in a high-temperature environment, and has significant economic value and social benefits.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a high temperature resistant poly 3,4-ethylenedioxythiophene chip-type laminated aluminum electrolytic capacitor comprises the following steps:

[0007] S1. Aluminum foil treatment: Place the aluminum foil in an oven and dry it at 105°C for 20 minutes;

[0008] S2, preparing a monomer mixture: ethanol and deionized water are mixed in a certain proportion, and then a certain mass of polysulfonic acid is added, and the mixture is stirred at a speed of 500 rpm for 5 minutes to be fully mixed, and finally 3,4-ethylenedioxythiophene monomer is added, and the mixture is stirred at a speed of 500 rpm for 15 minutes to obtain a monomer mixture;

[0009] S3, preparing an oxidizing solution: adding a certain mass fraction of an oxidant to deionized water, stirring at a speed of 500 rpm for 5 minutes, to obtain an oxidizing solution;

[0010] S4, chemical polymerization: the aluminum foil is immersed in the oxidizing solution for a certain period of time and then immediately immersed in deionized water, then immediately taken out and dried for 3 minutes, after the drying is completed, the aluminum foil is taken out and immersed in the monomer mixture for a certain period of time, then dried for 3 minutes, and the above steps are repeated 3 times, and then immersed in the monomer mixture, washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0011] S5, electrochemical polymerization: The first layer of poly (3,4-ethylenedioxythiophene) coated aluminum foil in S4 was connected to an external electrode as an anode, with a 2 cm 2 The carbon conductive electrode is used as the cathode, and constant current polymerization is carried out in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L polysulfonic acid at 10° C. for 24 hours, and then washed and dried to obtain a second layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0012] S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

[0013] Preferably, the volume ratio of deionized water to ethanol in step S2 is 2:8 to 8:2.

[0014] Preferably, the polysulfonic acid in step S2 is one or more of polyaniline sulfonic acid, diphenylamine sulfonic acid, tetrakis(4-sodium sulfonate phenyl)porphyrin, cobalt phthalocyanine tetrasulfonic acid, pyrene tetrasulfonic acid, pyrene disulfonic acid, and pyrene trisulfonic acid; and the added amount of the polysulfonic acid is 1 to 30%.

[0015] Preferably, the oxidant in step S3 is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide or potassium dichromate; and the added amount of the oxidant is 1-20%.

[0016] Preferably, in step S4, the time for immersing the aluminum foil in the oxidizing solution and the monomer mixture is 1 to 100 seconds.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The invention introduces a polysulfonic acid with a large molecular weight and a high melting point as a dopant and a crosslinking agent during the chemical polymerization and electrochemical polymerization process of preparing a poly 3,4-ethylenedioxythiophene sheet-type aluminum electrolytic capacitor, and realizes crosslinking between the poly 3,4-ethylenedioxythiophene molecular chains through the interaction between the sulfonic acid radical and the poly 3,4-ethylenedioxythiophene molecular chains with a positive charge, thereby improving the thermal stability of the poly 3,4-ethylenedioxythiophene molecular chains, and further obtaining a poly 3,4-ethylenedioxythiophene with a regular structure and high temperature resistance, so that the finally prepared aluminum electrolytic capacitor has the advantages of low leakage current, small equivalent series resistance, stable capacitance and the like when used for a long time in a high temperature environment, and the prepared electrode sheet has high surface regularity and an adjustable internal structure, and the preparation process has the advantages of being environmentally friendly and easy for industrial production and the like. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1:

[0021] S1. Aluminum foil treatment: 3VF aluminum foil (effective area 3.5 mm × 4.0 mm) was placed in an oven and dried at 105 °C for 20 min;

[0022] S2, preparing a monomer mixture: ethanol and deionized water were prepared into a 5L solution at a ratio of 7:3, then 400g of polyaniline sulfonic acid was added, and stirred at 500rpm for 5min to fully mix. Finally, 100g of 3,4-ethylenedioxythiophene monomer was added, and stirred at 500rpm for 15min to obtain a monomer mixture;

[0023] S3, preparing an oxidizing solution: adding 200 g of potassium dichromate oxidant to 5 L of deionized water, stirring at 500 rpm for 5 min to obtain an oxidizing solution;

[0024] S4, chemical polymerization: the aluminum foil was immersed in the oxidizing solution for 40 seconds and then immediately immersed in deionized water, then immediately taken out and dried in a 60°C oven for 3 minutes. After the drying, the aluminum foil was taken out and immersed in the monomer mixture for 60 seconds, and then dried for 3 minutes. The above steps were repeated 3 times, and then washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0025] S5, electrochemical polymerization: The first layer of poly 3,4-ethylenedioxythiophene coated aluminum foil in step S4 is connected to an external electrode as an anode, and a 2 cm 2The carbon conductive electrode is used as the cathode, and constant current polymerization is carried out in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L polyaniline sulfonic acid at 10° C. for 24 hours, and then washed and dried to obtain a second layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0026] S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

[0027] Embodiment 2:

[0028] S1. Aluminum foil treatment: 3VF aluminum foil (effective area 3.5 mm × 4.0 mm) was placed in an oven and dried at 105 °C for 20 min;

[0029] S2, prepare a monomer mixture: prepare 5L of solution by mixing ethanol and deionized water in a ratio of 8:2, then add 600g of pyrenetetrasulfonic acid, stir at 500rpm for 5min to mix well. Finally, add 100g of 3,4-ethylenedioxythiophene monomer, stir at 500rpm for 15min to obtain a monomer mixture;

[0030] S3, preparing an oxidizing solution: adding 150 g of ammonium persulfate oxidant to 5 L of deionized water, stirring at 500 rpm for 5 min to obtain an oxidizing solution;

[0031] S4, chemical polymerization: the aluminum foil was immersed in the oxidizing solution for 50 seconds and then immediately immersed in deionized water, then immediately taken out and dried in a 60°C oven for 3 minutes. After drying, the aluminum foil was taken out and immersed in the monomer mixture for 80 seconds, and then dried for 3 minutes. The above steps were repeated 3 times, and then washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0032] S5, electrochemical polymerization: The first layer of poly 3,4-ethylenedioxythiophene coated aluminum foil in step S4 is connected to an external electrode as an anode, and a 2 cm 2 The carbon conductive electrode is used as the cathode, and constant current polymerization is carried out in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L pyrenetetrasulfonic acid at 10° C. for 24 hours, and then washed and dried to obtain a second layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0033] S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

[0034] Example 3

[0035] S1. Aluminum foil treatment: 3VF aluminum foil (effective area 3.5 mm × 4.0 mm) was placed in an oven and dried at 105 °C for 20 min;

[0036] S2, preparing a monomer mixture: preparing a 5 L solution of ethanol and deionized water in a ratio of 3:7, then adding 800 g of tetrakis (4-sodium sulfonate phenyl) porphyrin, stirring at 500 rpm for 5 min to fully mix, and finally adding 100 g of 3,4-ethylenedioxythiophene monomer, stirring at 500 rpm for 15 min to obtain a monomer mixture;

[0037] S3, preparing an oxidizing solution: adding 180 g of sodium persulfate oxidant to 5 L of deionized water, stirring at 500 rpm for 5 min to obtain an oxidizing solution;

[0038] S4, chemical polymerization: the aluminum foil was immersed in the oxidizing solution for 60 seconds and then immediately immersed in deionized water, then immediately taken out and dried in a 60°C oven for 3 minutes. After drying, the aluminum foil was taken out and immersed in the monomer mixture for 75 seconds, and then dried for 3 minutes. The above steps were repeated 3 times, and then washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0039] S5, electrochemical polymerization: The first layer of poly 3,4-ethylenedioxythiophene coated aluminum foil in step S4 is connected to an external electrode as an anode, and a 2 cm 2 The carbon conductive electrode is used as the cathode. Constant current polymerization is carried out for 24 hours in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L tetrakis(4-sodium sulfonate phenyl)porphyrin at 10°C, and then the electrode sheet coated with the second layer of poly 3,4-ethylenedioxythiophene is prepared by washing and drying.

[0040] S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

[0041] Comparative Example 1

[0042] S1. Aluminum foil treatment: 3VF aluminum foil (effective area 3.5 mm × 4.0 mm) was placed in an oven and dried at 105 °C for 20 min;

[0043] S2, preparing a monomer mixture: ethanol and deionized water were prepared into a 5L solution at a ratio of 8:2, and then 600g of p-toluenesulfonic acid was added, and stirred at 500rpm for 5min to fully mix. Finally, 100g of 3,4-ethylenedioxythiophene monomer was added, and stirred at 500rpm for 15min to obtain a monomer mixture;

[0044] S3, preparing an oxidizing solution: adding 150 g of ammonium persulfate oxidant to 5 L of deionized water, stirring at 500 rpm for 5 min to obtain an oxidizing solution;

[0045] S4, chemical polymerization: the aluminum foil was immersed in the oxidizing solution for 60 seconds and then immediately immersed in deionized water, then immediately taken out and dried in a 60°C oven for 3 minutes. After drying, the aluminum foil was taken out and immersed in the monomer mixture for 75 seconds, and then dried for 3 minutes. The above steps were repeated 3 times, and then washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet;

[0046] S5, electrochemical polymerization: The first layer of poly 3,4-ethylenedioxythiophene coated aluminum foil in step S4 is connected to an external electrode as an anode, and a 2 cm 2 The carbon conductive electrode is used as the cathode. Constant current polymerization is carried out in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L p-toluenesulfonic acid at 10°C for 24 hours, and then washed and dried to obtain a second layer of poly 3,4-ethylenedioxythiophene coated electrode sheet.

[0047] S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

[0048] The 2.5V / 330μF capacitors prepared in the above Examples 1, 2 and 3 were tested for capacitance (C), leakage current (Lc) and equivalent series resistance (ESR) in a high temperature environment according to GB / T 6346.25-2018. The test results are shown in Table 1:

[0049] Table 1 Performance test results

[0050]

[0051] Through observation of the results of the three groups of embodiments, under the same heat treatment conditions, the capacitor prepared in Embodiment 2 has better comprehensive performance.

[0052] Subsequently, life tests were conducted on Example 2 and Comparative Example 1 at 145° C. and with a rated voltage of 2.5 V. The results are shown in Table 2, wherein the values ​​in brackets are percentages of performance changes.

[0053] Table 2 Performance test results

[0054]

[0055] Through the observation of Example 2 and Comparative Example 1, under the same conditions, the numerical change rates of the capacitance, leakage current and equivalent series resistance of the capacitor prepared in Example 2 are all smaller than the change rates of the capacitance, leakage current and equivalent series resistance of the capacitor prepared in Comparative Example 1, which indicates that the present invention can produce a poly (3,4-ethylenedioxythiophene) chip-type laminated aluminum electrolytic capacitor with low leakage current, small equivalent series resistance and stable capacitance when used for a long time in a high-temperature environment.

[0056] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a high temperature resistant poly 3,4-ethylenedioxythiophene chip-type laminated aluminum electrolytic capacitor, characterized in that: The following steps are involved: S1. Aluminum foil treatment: Place the aluminum foil in an oven and dry it at 105 °C for 20 min; S2, preparing a monomer mixture: ethanol and deionized water are mixed in a certain proportion, and then a certain mass of polysulfonic acid is added, and the mixture is stirred at a speed of 500 rpm for 5 min to be fully mixed, and finally 3,4-ethylenedioxythiophene monomer is added, and the mixture is stirred at a speed of 500 rpm for 15 min to obtain a monomer mixture, wherein the polysulfonic acid in step S2 is one or more of polyaniline sulfonic acid, diphenylamine sulfonic acid, tetrakis(4-sodium sulfonate phenyl)porphyrin, cobalt phthalocyanine tetrasulfonic acid, pyrene tetrasulfonic acid, pyrene disulfonic acid, and pyrene trisulfonic acid; the addition amount of the polysulfonic acid is 1-30%; S3, preparing an oxidizing solution: adding a certain mass fraction of an oxidant to deionized water, stirring at 500 rpm for 5 minutes, to obtain an oxidizing solution; S4, chemical polymerization: the aluminum foil is immersed in the oxidizing solution for a certain period of time and then immediately immersed in deionized water, then immediately taken out and dried for 3 minutes, after the drying is completed, the aluminum foil is taken out and immersed in the monomer mixture for a certain period of time, and then dried for 3 minutes, and the above steps are repeated 3 times, and then immersed in the monomer mixture, washed and dried to obtain the first layer of poly 3,4-ethylenedioxythiophene coated electrode sheet; S5, electrochemical polymerization: The first layer of poly 3,4-ethylenedioxythiophene coated aluminum foil in S4 was connected to an external electrode as an anode, and a 2 cm2 carbon conductive electrode was used as a cathode. Constant current polymerization was performed at 10 °C in an aqueous solution containing 0.4 mol / L 3,4-ethylenedioxythiophene monomer and 0.3 mol / L polysulfonic acid for 24 hours, and then washed and dried to obtain a second layer of poly 3,4-ethylenedioxythiophene coated electrode sheet; S6. The outer surface of the electrode sheet prepared in step S5 is coated with a carbon-containing conductive layer and a silver-containing conductive layer to obtain a monolithic capacitor element. The monolithic capacitor element is subjected to lamination bonding, epoxy resin encapsulation and aging to obtain the high-temperature resistant poly (3,4-ethylenedioxythiophene) chip-type aluminum electrolytic capacitor.

2. The method for preparing a high temperature resistant poly (3,4-ethylenedioxythiophene) chip-type laminated aluminum electrolytic capacitor according to claim 1, characterized in that: The volume ratio of deionized water to ethanol in step S2 is 2:8-8:

2.

3. The method for preparing a high temperature resistant poly 3,4-ethylenedioxythiophene chip-type laminated aluminum electrolytic capacitor according to claim 1, characterized in that: The oxidant in step S3 is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide or potassium dichromate; the added amount of the oxidant is 1-20%.

4. The method for preparing a high temperature resistant poly 3,4-ethylenedioxythiophene chip type laminated aluminum electrolytic capacitor according to claim 1, characterized in that: In step S4, the time for the aluminum foil to be immersed in the oxidizing solution and the monomer mixture is 1 to 100 seconds.

Images