阅读说明：本技术 一种漏电流小的固态铝电解电容器及其制备方法 (Solid-state aluminum electrolytic capacitor with small leakage current and preparation method thereof ) 是由 胡少强 刘一民 刘晓明 潘振炎 于 2021-06-11 设计创作，主要内容包括：一种漏电流小的固态铝电解电容器,包括芯包和外壳,芯包密封设置在外壳内,芯包包括阳极箔、电解纸和阴极箔,阳极箔和阴极箔之间形成有高分子导电聚合物,所述高分子导电聚合物包括PEDOT:PSS薄膜,在形成所述PEDOT:PSS薄膜的PEDOT:PSS分散液中加入有氨水,所述PEDOT:PSS分散液中PEDOT:PSS的重量浓度为0.5％-5％,PEDOT:PSS分散液的pH为4-6。在本发明中,PEDOT:PSS经过一定量的氨水处理后,在芯包中能够抑制PEDOT:PSS在阳极箔表面的降解,对甲苯磺酸因为分解产生的硫酸就少,对阳极箔表面的氧化铝的腐蚀就小,从而使得固态铝电解电容器的漏电流小。(A solid aluminum electrolytic capacitor with small leakage current comprises a core bag and a shell, wherein the core bag is arranged in the shell in a sealing mode, the core bag comprises an anode foil, electrolytic paper and a cathode foil, a high-molecular conductive polymer is formed between the anode foil and the cathode foil, the high-molecular conductive polymer comprises a PEDOT (polyethylene glycol terephthalate) PSS (Poly styrene) film, ammonia water is added into a PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid for forming the PEDOT (polyethylene glycol terephthalate) PSS film, the weight concentration of the PEDOT (polyethylene glycol terephthalate) PSS) in the PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid is 0.5% -5%, and the pH value of the PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid is 4-6. In the invention, after the PEDOT and PSS are treated by a certain amount of ammonia water, the degradation of the PEDOT and PSS on the surface of the anode foil can be inhibited in the core bag, the sulfuric acid generated by the decomposition of the p-toluenesulfonic acid is less, the corrosion to the aluminum oxide on the surface of the anode foil is less, and the leakage current of the solid aluminum electrolytic capacitor is small.)

1. The utility model provides a solid-state aluminium electrolytic capacitor that leakage current is little, includes core package and shell, the sealed setting of core package is in the shell, the core package includes anode foil, electrolytic paper and cathode foil, be formed with polymer conducting polymer between anode foil and the cathode foil, its characterized in that: the high-molecular conductive polymer comprises a PEDOT PSS film, ammonia water is added into a PEDOT PSS dispersion liquid for forming the PEDOT PSS film, the weight concentration of the PEDOT PSS in the PEDOT PSS dispersion liquid is 0.5% -5%, and the pH value of the PEDOT PSS dispersion liquid is 4-6.

2. The solid-state aluminum electrolytic capacitor with small leakage current according to claim 1, characterized in that: the weight ratio of PEDOT to PSS in PEDOT to PSS is 4:1-6: 1.

3. A method for manufacturing a solid-state aluminum electrolytic capacitor with small leakage current according to claim 1 or 2, characterized in that: comprises the following steps;

1) preparing a dispersion liquid; dispersing PEDOT (PSS) in a solvent, adding ammonia water after uniform dispersion, and stirring uniformly to obtain a dispersion liquid;

2) forming the core bag, cleaning and drying;

3) impregnating the core wrap treated in the step 1) with a pretreatment agent, and drying;

4) immersing the core bag impregnated with the pretreatment agent into the dispersion liquid obtained in the step 1), and drying; forming a PEDOT (PSS) film between the anode foil and the cathode foil;

5) impregnating with electrolyte;

6) assembling, cleaning and aging.

4. The method for manufacturing a solid aluminum electrolytic capacitor with small leakage current according to claim 3, characterized in that: the pretreatment agent in the step 2) is a silane coupling agent, and the impregnation time in the step 2) is 1-5 minutes; the drying temperature is 45-200 ℃ and the drying time is 1-3 hours.

5. The method for manufacturing a solid aluminum electrolytic capacitor with small leakage current according to claim 3, characterized in that: the electrolyte in the step 5) comprises a solvent and a solute, wherein the solvent comprises ethylene glycol; the solute comprises one or more of ammonium pelargonate, boric acid, ammonium azelate, ammonium pentaborate, mannitol and ammonium alkyl pelargonate; the additive comprises one or more of ammonium p-nitrophenylate, ammonium hypophosphite and graphite.

6. The method for manufacturing a solid aluminum electrolytic capacitor with small leakage current according to claim 3, characterized in that: the drying temperature in the step 4) is 120-180 ℃ for 20-40 minutes.

Technical Field

The invention relates to a solid aluminum electrolytic capacitor, in particular to a solid aluminum electrolytic capacitor taking PEDOT (PolyEthylenedimethylene Ether-Co-Acrylonitrile) PSS as a solid electrolyte and a preparation method thereof.

Background

The anode of the aluminum electrolytic capacitor is made of aluminum metal, a plurality of corrosion pits are formed on the surface of the anode foil, and a dielectric oxide film, namely an aluminum oxide film, is formed on the surface of the anode foil. The conductive electrolyte in contact with the oxide film plays a role of a true cathode in the electrolytic capacitor. As the true cathode of the capacitor, the quality of the electrolyte greatly affects the electrical performance of the aluminum electrolytic capacitor.

In order to achieve a large capacity of the aluminum electrolytic capacitor, an electrolytic paper is sandwiched between an anode foil and a cathode foil and wound together to form a core package; the solid aluminum electrolytic capacitor has conductive polymer adsorbed onto electrolytic paper.

In the conventional solid aluminum electrolytic capacitor, a core package is directly impregnated with a conductive high molecular polymer or impregnated with a monomer and an oxidant, such as 3, 4-ethylenedioxythiophene and iron p-toluenesulfonate, and a polymerization reaction is performed to form the conductive high molecular polymer. After the formation of the high-molecular conductive polymer, as the charge and discharge of the capacitor proceeds, the dopant is dedoped from the conductive high-molecular polymer, and an acid (e.g., sulfuric acid generated from p-toluenesulfonic acid) decomposed by the dopant corrodes the oxide film, resulting in problems in the electrical properties of the capacitor. Meanwhile, the electrochemical performance of the solid-state aluminum electrolytic capacitor is influenced by the defect of high surface roughness of the traditional PEDOT and PSS.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a solid-state aluminum electrolytic capacitor with small leakage current and a preparation method thereof; the polymer conductive polymer film of the solid aluminum electrolytic capacitor has small corrosion to the oxidation medium on the surface of the anode foil.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a solid aluminum electrolytic capacitor with small leakage current comprises a core bag and a shell, wherein the core bag is arranged in the shell in a sealing mode, the core bag comprises an anode foil, electrolytic paper and a cathode foil, a high-molecular conductive polymer is formed between the anode foil and the cathode foil, the high-molecular conductive polymer comprises a PEDOT (polyethylene glycol terephthalate) PSS (Poly styrene) film, ammonia water is added into a PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid for forming the PEDOT (polyethylene glycol terephthalate) PSS film, the weight concentration of the PEDOT (polyethylene glycol terephthalate) PSS) in the PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid is 0.5% -5%, and the pH value of the PEDOT (polyethylene glycol terephthalate) PSS dispersion liquid is 4-6.

Preferably, the weight ratio of PEDOT to PSS in the PEDOT to PSS is 4:1-6: 1.

The preparation method of the solid-state aluminum electrolytic capacitor with small leakage current comprises the following steps;

1) preparing a dispersion liquid; dispersing PEDOT (PSS) in a solvent, adding ammonia water after uniform dispersion, and stirring uniformly to obtain a dispersion liquid;

2) forming the core bag, cleaning and drying;

3) impregnating the core wrap treated in the step 1) with a pretreatment agent, and drying;

4) immersing the core bag impregnated with the pretreatment agent into the dispersion liquid obtained in the step 1), and drying; forming a PEDOT (PSS) film between the anode foil and the cathode foil;

5) impregnating with electrolyte;

6) assembling, cleaning and aging.

In the above method for manufacturing a solid aluminum electrolytic capacitor with small leakage current, preferably, the pretreatment agent in step 2) is a silane coupling agent, and the impregnation time in step 2) is 1 to 5 minutes; the drying temperature is 45-200 ℃ and the drying time is 1-3 hours.

In the above method for manufacturing a solid aluminum electrolytic capacitor with small leakage current, preferably, the electrolyte in step 5) includes a solvent and a solute, and the solvent includes ethylene glycol; the solute comprises one or more of ammonium pelargonate, boric acid, ammonium azelate, ammonium pentaborate, mannitol and ammonium alkyl pelargonate; the additive comprises one or more of ammonium p-nitrophenylate, ammonium hypophosphite and graphite.

In the above method for preparing a solid aluminum electrolytic capacitor with small leakage current, preferably, the drying temperature in the step 4) is 120-180 ℃ for 20-40 minutes.

Compared with the prior art, the invention has the advantages that: in the invention, after the PEDOT and PSS are treated by a certain amount of ammonia water, the degradation of the PEDOT and PSS on the surface of the anode foil can be inhibited in the core bag, the sulfuric acid generated by the decomposition of the p-toluenesulfonic acid is less, the corrosion to the aluminum oxide on the surface of the anode foil is less, and the leakage current of the solid aluminum electrolytic capacitor is small. Meanwhile, PEDOT: after the PSS is treated by ammonia water, the smoothness and the conductivity of the film are improved, so that the electrochemical performance of the solid-state aluminum electrolytic capacitor is enhanced to a certain extent.

Detailed Description

In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.

It should be particularly noted that when an element is referred to as being "fixed to, connected to or communicated with" another element, it can be directly fixed to, connected to or communicated with the other element or indirectly fixed to, connected to or communicated with the other element through other intermediate connecting components.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Example 1

A preparation method of a solid-state aluminum electrolytic capacitor with small leakage current comprises the following steps of 1) preparing dispersion liquid; dispersing PEDOT (PSS) in a solvent, adding ammonia water after uniform dispersion, and stirring uniformly to obtain a dispersion liquid; the weight concentration of PEDOT: PSS in the dispersion was 4%, and the pH of the PEDOT: PSS dispersion was 5.5. In this example, deionized water was used as the solvent of the dispersion. In this example, the weight ratio of PEDOT to PSS was 4:1, because the conductivity of the PEDOT to PSS film was required to be ensured.

2) The core bag is formed, washed and dried.

3) Impregnating the core wrap treated in the step 1) with a pretreatment agent, and drying; the pretreatment agent is a silane coupling agent, and the impregnation time in the step 2) is 1-5 minutes; the drying temperature is 45-200 ℃ and the drying time is 1-3 hours.

4) Impregnating the core bag impregnated with the pretreatment agent into the dispersion liquid obtained in the step 1); then drying to form a PEDOT: PSS film between the anode foil and the cathode foil, wherein the drying temperature is 120 ℃ and the time is 180 ℃ for 20-40 minutes. A film of PEDOT: PSS is formed between the anode foil and the cathode foil. During impregnation, a manner of multiple impregnation can be adopted, for example, twice impregnation is adopted, the time of the first impregnation is 2 minutes, and the temperature is normal temperature; directly drying at the temperature of 120-180 ℃ for 20-40 minutes after the first impregnation is finished; the second impregnation is performed in the same way as the first impregnation. The first impregnation and the second impregnation have the same steps and both comprise the following steps: putting the core bag into the impregnation liquid for normal-temperature impregnation for 2 minutes;

secondly, after impregnation is finished, the core bag is placed at normal temperature for 30-120 minutes to enable the core bag to naturally absorb the impregnation liquid;

and thirdly, if the bottom of the core bag has suspended liquid drops, the suspended liquid drops are sucked to be dry by using absorbent paper.

5) Impregnating with electrolyte; in this embodiment, the electrolyte is impregnated mainly for repairing the damage of the oxide film on the surface of the anode foil during the preparation process. The electrolyte may be a conventional electrolyte, for example, the electrolyte includes a solvent and a solute, and the solvent includes ethylene glycol; the solute comprises one or more of ammonium pelargonate, boric acid, ammonium azelate, ammonium pentaborate, mannitol and ammonium alkyl pelargonate; the additive comprises one or more of ammonium p-nitrophenylate, ammonium hypophosphite and graphite.

6) Assembling, cleaning and aging.

In the solid aluminum electrolytic capacitor obtained by the above method of this example, the film of PEDOT, PSS formed between the anode foil and the cathode foil was treated with ammonia. It is known that aqueous dispersions of PEDOT: PSS have a pH of 2 to 3, because in aqueous solutions the PEDOT: PSS is decomposed to some extent, which makes the dispersions acidic and this damages the oxide film on the surface of the anode foil. Of course, the damage can be repaired by the electrolyte impregnated in step 5). PSS film is formed between anode foil and cathode foil, the capacitor initially shows normal performance, but the dopant on the PEDOT chain, i.e. p-toluenesulfonic acid in this example, decomposes to generate sulfuric acid with the cycle of charging and discharging the capacitor, and damages the oxide film on the surface of the anode foil.

To verify the effect of the present example, comparative example 1, PEDOT in comparative example 1: PSS was not treated with ammonia, and the other steps were the same as in example 1.

The solid aluminum electrolytic capacitor of the comparative example and the 10 solid aluminum electrolytic capacitors of example 1 were charged and discharged 2000 times at a voltage and current of 45V and 20A, and the data are as follows:

as can be seen from the above table, the electrochemical performance of the solid-state aluminum electrolytic capacitor in example 1 is better than that of comparative example 1, and the LC value of example 1 is increased much less than that of comparative example 1.

For further illustration ammonia was used in PEDOT: PEDOT formed from PSS dispersion: the PSS film has an action mechanism in the process of uniformly coating the dispersion liquid obtained in the step 1) on an anode foil, and then drying to form PEDOT: PSS film, applied in such a way as to be spin-coated on the anode foil surface at 3500rpm for 30 seconds. For comparison, with PEDOT not treated with ammonia: the PSS dispersion was uniformly coated on the anode foil, and PEDOT: PSS film, the others being the same. The surface conductivity and roughness of the two films were measured, PEDOT treated with ammonia: the surface conductivity and the surface roughness of the PSS film are respectively 750S/cm and 0.71 nm; and PEDOT without ammonia treatment: the surface conductivity and surface roughness of the PSS film were 510S/cm and 0.91nm, respectively. From this it can be seen that by treating PEDOT with ammonia: PSS dispersion resulted in the formation of PEDOT: the PSS film has improved conductivity and reduced surface roughness. This is because, in PEDOT: adding ammonia water into the PSS dispersion, and adding PEDOT: PSS-H on PSS molecule can effectively react with PSS-NH₄Carrying out alternation; thereby breaking hydrogen bonds between PSS molecules; thereby causing the PSS units to be aggregated to a reduced extent with each other,thereby releasing part of PEDOT and improving the conductivity of the film; the degree of aggregation of the PSS units after breaking the hydrogen bonds is reduced, and the surface roughness of the film is also reduced. After film formation due to PEDOT: PSS-NH on PSS films₄The presence of (a) can inhibit the generation of sulfuric acid due to the decomposition of p-toluenesulfonic acid.