Conductive polymer dispersion liquid and electrolytic capacitor

Abstract

The invention provides a conductive polymer dispersion liquid for an electrolytic capacitor, the conductive polymer dispersion liquid comprises a conductive polymer, a solvent and an auxiliary agent, and the mass fraction of the auxiliary agent in the conductive polymer dispersion liquid is 0.1-20%; the auxiliary agent comprises a compound A and a compound B; the compound A is selected from at least one of compounds shown in the following structural general formula: R1R2R3 (CH3) NOH, R1, R2 and R3 are independently selected from H, aliphatic groups, adamantyl, hydroxyl-substituted alkyl and benzyl, and R1, R2 and R3 are not H at the same time; and the compound B is selected from at least one of organic compounds with molecular weight less than 400 and at least two oxygen-containing polar groups. The conductive polymer dispersion liquid provided by the invention has the characteristics of low melting point, low vapor pressure and high viscosity, can effectively improve the initial capacity extraction of the electrolytic capacitor, improves the ESR, low-temperature capacitance attenuation characteristic and anti-vibration characteristic, and prolongs the service life.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytic capacitor materials, and in particular relates to a conductive polymer dispersion and an electrolytic capacitor. Background Art

[0002] An electrolytic capacitor is a polarized capacitor whose anode or positive plate is made of metal that forms an insulating oxide layer through anodic oxidation. This oxide layer acts as the dielectric of the capacitor. A solid, liquid or gel electrolyte covers the surface of this oxide layer and acts as the cathode or negative plate of the capacitor.

[0003] As one of the core materials of electrolytic capacitors, the cathode material is determined by the material's own properties, the interface relationship between the material and the dielectric layer, the material and the lead-out electrode, and the material isolation layer. Currently, there are conductive polymer systems, including polyaniline, polypyrrole, polythiophene, PBFDO, etc., which are used to prepare cathode materials, but the initial capacity lead-out, ESR, low-temperature capacity decay characteristics, and anti-vibration characteristics of the prepared electrolytic capacitors need to be further improved. Summary of the invention

[0004] Based on this, the object of the present invention is to provide a conductive polymer dispersion, which can effectively increase the initial capacity of electrolytic capacitors, improve ESR, low temperature capacity decay characteristics and anti-vibration characteristics, and extend service life.

[0005] To achieve the above object, the present invention adopts the following technical solution.

[0006] In a first aspect of the present invention, a conductive polymer dispersion for an electrolytic capacitor is provided, wherein the conductive polymer dispersion comprises a conductive polymer, a solvent and an auxiliary agent, wherein the mass fraction of the auxiliary agent in the conductive polymer dispersion is 0.1% to 20%;

[0007] The auxiliary agent comprises compound A and compound B; the compound A is selected from at least one of the compounds represented by the following general structural formula: R 1 R 2 R 3 (CH 3 )NOH, where R 1 , R 2 and R 3 are independently selected from H, aliphatic hydrocarbon, adamantyl, hydroxy-substituted alkyl, benzyl, and R 1 , R 2 and R 3 The compound B is not H at the same time; the compound B is selected from at least one organic compound having a molecular weight of less than 400 and at least two oxygen-containing polar groups.

[0008] In some embodiments, the aliphatic hydrocarbon group includes methyl, ethyl, isopropyl, tert-butyl, butyl, isooctyl, and dodecyl; and / or the oxygen-containing polar group includes hydroxyl and carboxyl.

[0009] Preferably, the compound A is selected from at least one of tetramethylammonium hydroxide, N-methyl-triethanolammonium hydroxide, N-methyl-triethylammonium hydroxide, N,N,N-trimethyl-adamantylammonium hydroxide, N,N,N-trimethyl-hydroxyethanolammonium hydroxide and N,N,N-trimethyl-benzylammonium hydroxide.

[0010] Preferably, the compound B is selected from at least one of oxalic acid, citric acid, tartaric acid, malic acid, ethylene glycol, glycerol, polyglycerol, erythritol, mannitol, gallic acid, salicylic acid, and phytic acid.

[0011] Preferably, the mass fraction of the auxiliary agent in the conductive polymer dispersion is 2% to 12%.

[0012] In some embodiments, the molar ratio of the compound A to the compound B is 1:10 to 10:1; preferably, the molar ratio of the compound A to the compound B is 3:7 to 7:3.

[0013] In some embodiments, the conductive polymer is selected from at least one of polyaniline and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, polybenzofurandione and its derivatives.

[0014] In some embodiments, the mass fraction of the conductive polymer in the conductive polymer dispersion is 0.8% to 20%.

[0015] In some embodiments, the solvent is selected from at least one of water, methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane; preferably, the mass fraction of the solvent in the conductive polymer dispersion is 60 to 99%.

[0016] According to a second aspect of the present invention, there is provided an electrolytic capacitor comprising a solid electrolyte layer formed from the conductive polymer dispersion as described above.

[0017] In some embodiments, the electrolytic capacitor is an aluminum electrolytic capacitor, an aluminum laminated electrolytic capacitor, a solid-liquid hybrid electrolytic capacitor, or a tantalum electrolytic capacitor.

[0018] The present invention provides a conductive polymer dispersion, which includes a conductive polymer, a solvent and an auxiliary agent, wherein the auxiliary agent includes compound A and compound B, wherein compound A has an oleophilic alkyl structure, which can reduce the dynamic and static surface tension of the conductive polymer dispersion, thereby better filling in the electrolytic capacitor, which is conducive to the reduction of ESR; compound B has an oxygen-containing polar group, which can drive the conductive polymer material into the holes of the dielectric layer, and through the sawtooth structure formed in the middle of the dielectric layer, the interface contact is enhanced, which is conducive to the extraction of capacity. Further, the inventors have found through research that when the compound A and the compound B are in a suitable molar ratio range, the nitrogen cation structure that can accept electrons and the oxygen atom that gives electrons can form a weak interaction, thereby achieving eutectic properties, giving the conductive polymer dispersion the characteristics of low melting point, low vapor pressure and high viscosity. The low melting point will improve the contact between the conductive polymer material and the dielectric layer at low temperatures, thereby better improving the low-temperature capacitance decay characteristics; the low vapor pressure will effectively reduce gas production when the electrolytic capacitor is under a load of 125°C, further improving the high-temperature life; the high viscosity will closely combine the conductive polymer material with other components such as the dielectric layer, thereby better improving the anti-vibration characteristics of the electrolytic capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of Example 3.

[0020] Figure 2 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of Comparative Example 1.

[0021] Figure 3 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of comparative example 2.

[0022] Figure 4 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of comparative example 3. DETAILED DESCRIPTION

[0023] The experimental methods in the following examples of the present invention without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0024] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0026] In the present invention, "at least one" refers to one or more than one. "And / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0027] This embodiment provides a conductive polymer dispersion for an electrolytic capacitor, the conductive polymer dispersion comprising a conductive polymer, a solvent and an auxiliary agent, wherein the mass fraction of the auxiliary agent in the conductive polymer dispersion is 0.1% to 20%;

[0028] The auxiliary agent comprises compound A and compound B; the compound A is selected from at least one of the compounds represented by the following general structural formula: R 1 R 2 R 3 (CH 3 )NOH, where R 1 , R 2 and R 3 are independently selected from H, aliphatic hydrocarbon, adamantyl, hydroxy-substituted alkyl, benzyl, and R 1 , R 2 and R 3 The compound B is not H at the same time; the compound B is selected from at least one organic compound having a molecular weight of less than 400 and at least two oxygen-containing polar groups.

[0029] The compound A has a lipophilic alkyl structure, which can reduce the dynamic surface tension of the conductive polymer dispersion, so that it can be better filled in the electrolytic capacitor, which is beneficial to the reduction of ESR; compound B has an oxygen-containing polar group, which can drive the conductive polymer material into the pores of the dielectric layer, and enhance the interface contact by forming a sawtooth structure in the middle of the dielectric layer, which is beneficial to the extraction of capacity. In particular, when the molar ratio of the compound A to the compound B is 1:10 to 10:1, A and B can form a eutectic structure through intermolecular interactions, so that in addition to the functions of reducing ESR of component A and attracting capacitance of component B, the eutectic component formed also has the additional functions of improving low-temperature capacity, high-temperature life and shock resistance. Preferably, the molar ratio of the compound A to the compound B is 3:7 to 7:3. Within this molar ratio range, the performance of the electrolytic capacitor can be better.

[0030] In some embodiments, the aliphatic hydrocarbon group includes methyl, ethyl, isopropyl, tert-butyl, butyl, isooctyl, and dodecyl; and / or the oxygen-containing polar group includes hydroxyl and carboxyl.

[0031] Preferably, the compound A is selected from at least one of tetramethylammonium hydroxide, N-methyl-triethanolammonium hydroxide, N-methyl-triethylammonium hydroxide, N,N,N-trimethyl-adamantylammonium hydroxide, N,N,N-trimethyl-hydroxyethanolammonium hydroxide and N,N,N-trimethyl-benzylammonium hydroxide.

[0032] Preferably, the compound B is selected from at least one of oxalic acid, citric acid, tartaric acid, malic acid, ethylene glycol, glycerol, polyglycerol, erythritol, mannitol, gallic acid, salicylic acid, and phytic acid.

[0033] Specifically, the mass fraction of the auxiliary agent in the conductive polymer dispersion can be but is not limited to 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 7.5%, 9%, 10%, 12%, 15%, 16%, 17%, 18%, 19%, 20%.

[0034] When the mass fraction of the auxiliary agent in the conductive polymer dispersion is 0.1% to 20%, the low-temperature capacity decay characteristics, high-temperature life and anti-vibration characteristics of the electrolytic capacitor can be effectively improved. When the mass fraction of the auxiliary agent in the conductive polymer dispersion is less than 0.1%, there is no obvious improvement on the performance; and when it is greater than 20%, the conductive ability of the conductive polymer in the mesopores will be diluted, resulting in an increase in reactive power. In particular, when the mass fraction of the auxiliary agent in the conductive polymer dispersion is 2% to 12%, the performance improvement effect on the electrolytic capacitor is better.

[0035] In some embodiments, the conductive polymer is selected from at least one of polyaniline and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, polybenzofurandione and its derivatives.

[0036] In some embodiments, the mass fraction of the conductive polymer in the conductive polymer dispersion is 0.8% to 20%. Specifically, the mass fraction of the conductive polymer in the conductive polymer dispersion can be, but is not limited to, 0.8%, 1%, 2%, 3%, 4%, 5%, 7.5%, 9%, 10%, 12%, 15%, 16%, 17%, 18%, 19%, 20%.

[0037] In some embodiments, the solvent is selected from at least one of water, methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane.

[0038] Preferably, the mass fraction of the solvent in the conductive polymer dispersion is 60 to 99%.

[0039] The preparation method of the conductive polymer dispersion of the present invention can be generally used by conventional preparation methods in the art. Preferably, the following preparation method can be used: (1) weighing the compound A and the compound B in proportion, mixing them evenly, to obtain a mixture; (2) adding the conductive polymer to a solvent, then adding the mixture in step (1), and then homogenizing with a homogenizer to obtain the conductive polymer dispersion.

[0040] Another embodiment of the present invention provides an electrolytic capacitor including a solid electrolyte layer formed of the conductive polymer dispersion as described above.

[0041] In some embodiments, the electrolytic capacitor is an aluminum electrolytic capacitor, an aluminum laminated electrolytic capacitor, a solid-liquid hybrid electrolytic capacitor, or a tantalum electrolytic capacitor.

[0042] In some embodiments, the preparation method of the electrolytic capacitor includes the following steps: (1) soaking the capacitor element or the anode body in the conductive polymer dispersion at a pressure of -95KPa to +100KPa for 1 to 40 minutes; taking out and drying, the drying process is 80 to 190°C for 5 to 60 minutes. (2) The process of the above step (1) is impregnated once, and the impregnation is repeated 0 to 4 times; (3) After the impregnation is completed, other post-processing processes can be used, and the sealing assembly can be assembled to obtain the electrolytic capacitor.

[0043] The following describes the invention in conjunction with specific embodiments.

[0044] Example 1

[0045] This example is used to illustrate the preparation method of the conductive polymer dispersion and electrolytic capacitor disclosed in the present invention, which includes the following steps:

[0046] (1) weighing the compound A and the compound B in proportion, mixing them evenly to obtain a mixture; adding the conductive polymer to solvent water, then adding the mixture, and then homogenizing using a homogenizer to obtain the conductive polymer dispersion;

[0047] (2) soaking the capacitor element in the conductive polymer dispersion at a pressure of -0.09 KPa for 20 minutes; taking it out and drying it at 125° C. for 60 minutes;

[0048] (3) The process of step (2) above is impregnated once, and the impregnation is repeated 3 times;

[0049] (4) After the impregnation is completed, the capacitor elements are sealed and assembled to obtain the electrolytic capacitor.

[0050] The types and amounts of compound A and compound B, and the type and amount of the conductive polymer are shown in Table 1, and the remainder is the solvent.

[0051] Embodiments 2 to 15

[0052] Examples 2 to 15 are used to illustrate a method for preparing a conductive polymer dispersion and an electrolytic capacitor disclosed in the present invention, which include most of the operations in Example 1, except for the composition of the conductive polymer dispersion, as shown in Table 1.

[0053] Comparative Examples 1 to 5

[0054] Comparative Examples 1 to 5 are used to illustrate a method for preparing a conductive polymer dispersion and an electrolytic capacitor disclosed in the present invention, which include most of the operations in Example 1, except for the composition of the conductive polymer dispersion, as shown in Table 1.

[0055] Table 1

[0056]

[0057]

[0058]

[0059] The following properties of the electrolytic capacitors prepared in the above examples and comparative examples were tested under the following conditions:

[0060] 1. Initial capacity extraction: 25℃, 120Hz;

[0061] 2. Initial ESR: 25℃, 100KHz.

[0062] 3. Low temperature capacity decay: -55℃ for 4 hours, the capacity value measured at 120Hz is the decay ratio of the initial capacity.

[0063] 4. Anti-vibration performance: 10 capacitors are placed in a 100mL PP bottle and dropped from a height of 1.5 meters onto a concrete floor. The number of drops when the capacity change rate of one capacitor is >3%.

[0064] 5. Service life: 125℃, rated voltage, ESR change rate>50%.

[0065] 6.Capacitor specification: 16V470uF.

[0066] Fill in the performance test results in Table 2.

[0067] Table 2

[0068]

[0069]

[0070] The above results show that the electrolytic capacitors of the present invention (Examples 1 to 15) have the advantages of high initial capacity extraction, low ESR, good low temperature capacity decay characteristics and anti-vibration characteristics, and long service life. The conductive polymer dispersion of the present invention comprises compound A and compound B. Compound A has an alkyl structure with lipophilicity, which can reduce the dynamic and static surface tension of the conductive polymer dispersion, thereby better filling in the electrolytic capacitor, which is conducive to reducing ESR; compound B has an oxygen-containing polar group, which can drive the conductive polymer material into the holes of the dielectric layer, and through the sawtooth structure formed in the middle of the dielectric layer, the interface contact is enhanced, which is conducive to the extraction of capacity.

[0071] By comparing Examples 1 to 13 and Examples 14 to 15, it can be seen that when the molar ratio of compound A to compound B in the conductive polymer dispersion is 1:10 to 10:1 (Examples 1 to 13), the electrolytic capacitor can obtain better comprehensive performance. This is because when the molar ratio of compound A to compound B is 1:10 to 10:1, the two can form a eutectic in the conductive polymer dispersion, further giving the conductive polymer dispersion the characteristics of low melting point, low vapor pressure and high viscosity, thereby making the relevant performance of the electrolytic capacitor better. When the molar ratio of compound A to compound B in the conductive polymer dispersion is not within the range of 1:10 to 10:1 (Examples 14 to 15), due to the presence of compound A and compound B, the relevant performance of the electrolytic capacitor is improved to a certain extent, but is slightly worse than that of Examples 1 to 13.

[0072] Compared with Example 3, the conductive polymer dispersion in Comparative Example 1 does not contain the auxiliary agent, resulting in a decrease in the initial capacity of the prepared electrolytic capacitor, deterioration in low-temperature capacity decay characteristics and anti-vibration characteristics, and a shortened service life.

[0073] Compared with Example 3, the auxiliary agent in Comparative Example 2 does not contain compound B, and the auxiliary agent in Comparative Example 3 does not contain compound A, both of which lead to deterioration of the low-temperature capacity decay, seismic resistance and high-temperature life of the prepared electrolytic capacitor.

[0074] Compared with Example 3, the content of the auxiliary agent in the conductive polymer dispersion of Comparative Example 4 is too low, resulting in no significant improvement in performance and failure to achieve the expected physical fitness improvement; the content of the auxiliary agent in the conductive polymer dispersion of Comparative Example 5 is too high, resulting in a significant increase in ESR.

[0075] Figure 1 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of Example 3; Figure 2 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of Comparative Example 1; Figure 3 This is the positive foil image after impregnation with the conductive polymer dispersion liquid of Comparative Example 2; Figure 4 This is the positive foil image after impregnation with the conductive polymer dispersion in comparative example 3. Figures 1 to 4 It can be seen from the comparison that, compared with Comparative Example 1, Comparative Examples 2 and 3, which only add Compound A or Compound B, both increase the deposition of polymer on the surface of the positive foil, which is highly related to the improvement of a certain characteristic of the capacitor by a single component. However, compared with Comparative Examples 2 and 3, in Example 3, Compound A and Compound B are added at the same time, which can form a more uniform and thick polymer layer on the positive foil, thereby effectively increasing the initial capacity of the electrolytic capacitor and reducing the ESR. The reason is that when the dispersion is solidified, the eutectic monomer is in a high-viscosity flow state, which can drive the polymer to level and hang liquid in the medium pores.

[0076] In summary, the present invention can effectively improve the ESR, low-temperature capacitance decay characteristics and anti-vibration characteristics of the electrolytic capacitor and extend its service life by optimizing the composition of the conductive polymer dispersion.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A conductive polymer dispersion for electrolytic capacitors, characterized in that: The conductive polymer dispersion comprises a conductive polymer, a solvent and an auxiliary agent, wherein the mass fraction of the auxiliary agent in the conductive polymer dispersion is 0.1% to 20%; The auxiliary agent comprises compound A and compound B; the compound A is selected from at least one of the compounds represented by the following general structural formula: R1R2R3(CH3)NOH, wherein R1, R2 and R3 are independently selected from H, aliphatic hydrocarbon group, adamantyl group, hydroxyl-substituted alkyl group, benzyl group, and R1, R2 and R3 are not H at the same time; the compound B is selected from at least one of the organic compounds having a molecular weight of less than 400 and having at least two oxygen-containing polar groups.

2. The conductive polymer dispersion according to claim 1, characterized in that The aliphatic hydrocarbon group includes methyl, ethyl, isopropyl, tert-butyl, butyl, isooctyl, and dodecyl; and / or the oxygen-containing polar group includes hydroxyl and carboxyl.

3. The conductive polymer dispersion according to claim 1, characterized in that The compound A is selected from at least one of tetramethylammonium hydroxide, N-methyl-triethanolammonium hydroxide, N-methyl-triethylammonium hydroxide, N,N,N-trimethyl-adamantylammonium hydroxide, N,N,N-trimethyl-hydroxyethanolammonium hydroxide and N,N,N-trimethyl-benzylammonium hydroxide.

4. The conductive polymer dispersion according to claim 1, characterized in that The compound B is selected from at least one of oxalic acid, citric acid, tartaric acid, malic acid, ethylene glycol, glycerol, polyglycerol, erythritol, mannitol, gallic acid, salicylic acid, and phytic acid.

5. The conductive polymer dispersion according to claim 1, characterized in that The mass fraction of the auxiliary agent in the conductive polymer dispersion is 2% to 12%.

6. The conductive polymer dispersion according to claim 1, wherein The molar ratio of the compound A to the compound B is 1:10 to 10:1; preferably, the molar ratio of the compound A to the compound B is 3:7 to 7:

3.

7. The conductive polymer dispersion according to claim 1, characterized in that the conductive polymer is at least one selected from polyaniline and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, polybenzofurandione and its derivatives. 8 . The conductive polymer dispersion according to claim 1 , wherein the mass fraction of the conductive polymer in the conductive polymer dispersion is 0.8% to 20%.

9. An electrolytic capacitor, characterized in that: The electrolytic capacitor comprises a solid electrolyte layer formed from the conductive polymer dispersion according to any one of claims 1 to 8.

10. The electrolytic capacitor according to claim 9, wherein: The electrolytic capacitor is an aluminum electrolytic capacitor, an aluminum laminated electrolytic capacitor, a solid-liquid hybrid electrolytic capacitor, or a tantalum electrolytic capacitor.

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