Electrolytic capacitor based on n-type conductive polymer, and manufacturing process therefor

Abstract

Provided are an electrolytic capacitor based on an n-type conductive polymer, and a manufacturing process therefor. The electrolytic capacitor comprises a wound body which is formed by sequentially laminating a negative electrode foil, electrolytic paper, and a positive electrode foil having an oxide film dielectric formed on the surface thereof and then winding same. An n-type conductive polymer electrolyte layer is provided in the wound body, the material of the n-type conductive polymer electrolyte layer comprising one or more n-type conductive polymers, and the n-type conductive polymer containing the following repeating units having a conjugated structure carrying a negative charge: formula (I), wherein X is one of an oxygen atom, a sulfur atom, a selenium atom, a tellurium atom and a nitrogen atom; when X is a nitrogen atom, R is one of a hydrogen atom, a linear alkyl group and an isomeric alkyl group; when X is one of an oxygen atom, a sulfur atom, a selenium atom and a tellurium atom, R is not present; Y+ represents a cation; and the repeating units having a conjugated structure carrying a negative charge may be the same or different. The formed capacitor has a low ESR and high stability.

Description

Electrolytic capacitor based on n-type conductive polymer and its preparation process Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to an electrolytic capacitor based on an n-type conductive polymer and a preparation process thereof. Background Art

[0002] Conductive polymers can be divided into two categories based on their preparation methods and conductive mechanisms: intrinsically conductive polymers and composite conductive polymers. Intrinsically conductive polymers possess a π-conjugated structure, which allows for sufficient delocalization of charge carriers within the backbone, resulting in conductivity. Since conjugated polymers with π-conjugated structures typically have very low carrier concentrations, exhibiting semiconductor properties, external agents (such as doping) are necessary to increase the carrier concentration and modify the original band structure to create favorable conditions for electron delocalization and achieve conductivity. Doping can be categorized as p-type doping and n-type doping. P-type doping generally refers to the process of partially oxidizing the π-conjugated backbone of an organic conjugated polymer to produce freely mobile cationic charge carriers. This process was first discovered in trans-polyacetylene. By treating trans-polyacetylene with reagents such as iodine, approximately 85% of the positive charge can be delocalized across more than 15 repeating units, resulting in an increase in the conductivity of polyacetylene by more than seven orders of magnitude. At present, a variety of p-type conductive polymers have been developed, including poly (3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI) and polypyrrole (PPy).

[0003] Despite significant breakthroughs in the synthesis and preparation of conductive polymers, most doping methods still focus on p-type doping, resulting in hole-dominated charge transport behavior in these polymers. The development of n-type conductive polymers lags far behind, primarily due to low doping efficiency and poor stability. For example, the conductivity of lithium-doped n-type polyacetylene is significantly lower than that of iodine-doped p-type polyacetylene, and it also struggles to maintain stability in air.

[0004] In the current capacitor industry, both solid-liquid hybrid and solid aluminum electrolytic capacitors use PEDOT as a conductive polymer. PEDOT is a p-type doped conductive polymer material that conducts electricity through cationic carriers (holes). It has the following characteristics in capacitor applications: ① Its main chain carries a positive charge, making it a long-term capacitor cathode. During its long-term use as a capacitor cathode, PEDOT is easily attacked by oxygen during the process of storing and outputting electrons, resulting in dedoping problems, a decrease in conductivity, and capacitor failure. ② The equivalent series resistance (ESR) of a capacitor is largely determined by the conductivity of the conductive polymer, and the upper limit of PEDOT's conductivity is typically less than 500 S / cm. ③ The thermal decomposition temperature of currently synthesized PEDOT is generally below 200°C. This low thermal decomposition temperature makes it difficult to adapt to high-temperature operating environments above 150°C when used as a working electrolyte in solid-state capacitors, leading to a bottleneck in the research of high-temperature solid-state capacitors. Currently, there are almost no solid-state capacitors on the market that can operate at temperatures exceeding 150°C. ④PEDOT is insoluble in solvents. In actual production, it needs to be dispersed in water with a dispersant to form a dispersion liquid. However, its dispersion degree is very low and it is easy to agglomerate, which requires a very high timeliness of use.

[0005] Summary of the Invention

[0006] To address the technical problems of existing p-type conductive polymer materials used in electrolytic capacitors, such as easy dedoping, low conductivity, poor thermal stability, and poor dispersibility of impregnation solutions, the present invention provides an electrolytic capacitor based on an n-type conductive polymer and a preparation process thereof. By combining the n-type conductive polymer with process improvements, a capacitor negative electrode electrolyte with a conductivity exceeding 500 S / cm can be obtained, and an electrolytic capacitor with ultra-low ESR and ultra-high stability can be realized.

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] The present invention provides an electrolytic capacitor based on an n-type conductive polymer, comprising a wound body formed by stacking a negative electrode foil, an electrolytic paper, and a positive electrode foil having an oxide film dielectric formed on the surface in sequence;

[0009] It is characterized in that: the winding body has an n-type conductive polymer electrolyte layer;

[0010] The material of the n-type conductive polymer electrolyte layer includes one or more n-type conductive polymers, and the n-type conductive polymer has the following repeating units with negatively charged conjugated structures:

[0011] wherein X is one of oxygen, sulfur, selenium, tellurium, and nitrogen; when X is nitrogen, R is one of hydrogen, linear alkyl, and isomeric alkyl; when X is one of oxygen, sulfur, selenium, and tellurium, R is absent; Y + represents a cation; the repeating units of the negatively charged conjugated structure are the same or different.

[0012] Furthermore, the conductivity of the n-type conductive polymer is 500 S / cm to 8000 S / cm; the molecular weight of the n-type conductive polymer is at least 1 kDa, preferably the molecular weight of the n-type conductive polymer is 100 kDa to 5000 kDa;

[0013] The cation is selected from one or more of hydrogen ions, quaternary ammonium ions, pyridinium ions, and metal ions.

[0014] Furthermore, the weight proportion of the n-type conductive polymer electrolyte layer in the wound body is at least 1%.

[0015] Furthermore, the electrolytic capacitor further includes an electrolyte for impregnating the wound body, a shell for accommodating the wound body and the electrolyte, and a sealing member for sealing the shell;

[0016] The electrolyte comprises the following components: a solvent, a solute and an additive;

[0017] The solvent is selected from an aprotic polar solvent or a protic polar solvent; the aprotic polar solvent is selected from one or more of gamma-butyrolactone (GBL), sulfolane (SFL), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N-methylformamide (NMF); the protic polar solvent is selected from one or more of ethylene glycol, glycerol, diethylene glycol, triethylene glycol, polyglycerol, polyglycerol ether, and other polyols containing multiple hydroxyl groups;

[0018] The solute is selected from one or more of organic acids, inorganic acids, and organic bases; the organic acid is selected from one or more of phthalic acid, isophthalic acid, terephthalic acid, maleic acid, adipic acid, benzoic acid, malonic acid, succinic acid, and boronized disalicylic acid;

[0019] The organic base is selected from organic amines and / or imidazoline compounds; the organic amine is selected from primary amines, secondary amines, tertiary amines, etc., the primary amines include methylamine, ethylamine, propylamine, etc., the secondary amines are selected from dimethylamine, diethylamine, ethylmethylamine, dibutylamine, diisopropylamine, etc., the tertiary amines are selected from trimethylamine, triethylamine, tributylamine, ethyldiisopropylamine, etc.; the imidazoline is selected from ethyldimethylimidazoline, 1,2,3,4-tetramethylimidazoline, etc.;

[0020] The additive is selected from nitro compounds, such as p-nitrobenzoic acid, m-nitroacetophenone, p-nitrobenzyl alcohol, etc.

[0021] Furthermore, the housing is made of metal;

[0022] The electrolytic paper is selected from artificial fibers and / or natural fibers; artificial fibers such as polyester fibers, polyamide fibers, polypropylene fibers, aramid fibers, cellulose fibers (such as viscose fibers, acetate fibers, cuprammonium fibers, etc.); natural fibers such as abaca, Spanish grass, cotton fibers, etc.

[0023] The positive electrode foil and the negative electrode foil are respectively made of aluminum valve metal; and lead-out guide pins are respectively provided on the positive electrode foil and the negative electrode foil.

[0024] Another aspect of the present invention provides a process for preparing the above-mentioned electrolytic capacitor based on n-type conductive polymer, comprising the following steps:

[0025] (1) Winding the positive electrode foil, electrolytic paper, and negative electrode foil in sequence into a first winding body of required specifications, subjecting the first winding body to at least one forming treatment, wherein the forming treatment includes forming first and then drying, to obtain a second winding body;

[0026] (2) forming an electrolyte layer having the n-type conductive polymer in the second wound body to obtain a third wound body;

[0027] (3) After being placed in a housing and sealed, the housing is powered and aged to obtain an electrolytic capacitor based on an n-type conductive polymer.

[0028] Furthermore, the process of forming the electrolyte layer having the n-type conductive polymer in step (2) is: placing the second winding body in an n-type conductive polymer solution and performing at least one impregnation treatment, the impregnation treatment including first impregnation and then drying; the n-type conductive polymer solution contains one or more of the n-type conductive polymers.

[0029] Furthermore, the n-type conductive polymer solution comprises 0.1 wt% to 10 wt% of the n-type conductive polymer, and the balance is an organic solution to make up 100 wt%. The organic solution is selected from one or more of aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, amines, esters, ethers, ketones, dimethyl sulfoxide, amides (such as N,N-dimethylformamide and N-methylformamide), and sulfolane. It should be understood that amines and amides are not the same substance. Amines include primary amines, secondary amines, and tertiary amines. Preferably, the n-type conductive polymer solution comprises 0.5 wt% to 3 wt% of the n-type conductive polymer, and the balance is an organic solution to make up 100 wt%.

[0030] Furthermore, the process of forming the electrolyte layer having the n-type conductive polymer in step (2) is as follows: the second wound body is subjected to the steps of impregnation with an n-type conductive polymer monomer solution, drying, impregnation with an oxidant solution, and drying at least once in a step-by-step impregnation manner to obtain a third wound body, wherein the n-type conductive polymer monomer solution contains one or more n-type conductive polymer monomers;

[0031] Alternatively, the process of forming the electrolyte layer having the n-type conductive polymer in step (2) is: dripping a mixed solution containing one or more n-type conductive polymer monomers and an oxidant into the second wound body at least once by drip irrigation, then heating and polymerizing the mixed solution at least once, and then drying the mixed solution to obtain a third wound body;

[0032] The n-type conductive polymer monomer has the following structure:

[0033] wherein X is one of an oxygen atom, a sulfur atom, a selenium atom, a tellurium atom, and a nitrogen atom; when X is a nitrogen atom, R is one of a hydrogen atom, a linear alkyl group, and an isomeric alkyl group; when X is one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom, R does not exist.

[0034] Furthermore, in step (2) of adopting the stepwise impregnation method, the n-type conductive polymer monomer solution contains 0.1 wt% to 5 wt% of the n-type conductive polymer monomer and the balance is supplemented to 100 wt% of the organic solution;

[0035] The heating polymerization in step (2) using the drip irrigation method is carried out at 50° C. to 150° C. under nitrogen protection, preferably at 70-120° C., more preferably 80-100° C., and most preferably 80° C.; wherein the mixed solution containing one or more n-type conductive polymer monomers and an oxidant comprises the n-type conductive polymer monomers, the oxidant, and an organic solution, wherein the mass concentration of the n-type conductive polymer monomers is 1wt% to 5wt%, and the mass concentration of the oxidant is 1wt% to 5wt%;

[0036] The oxidant solution contains 0.1wt% to 10wt% of an oxidant and an organic solution whose balance is supplemented to 100wt%; the oxidant is selected from one or more of oxygen, peroxides, metal salts, persulfates, perborates, hypohalites, quinone compounds, and perbenzoic acids; and the organic solution is selected from one or more of aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, amines, esters, ethers, ketones, dimethyl sulfoxide, amides, and sulfolane.

[0037] Furthermore, in step (2) of the stepwise impregnation method, after the steps of impregnating and drying the oxidant solution, the step of impregnating the additive compound solution is further included, wherein the additive compound solution contains 1 wt% to 5 wt% of the additive compound and the balance is an organic solution supplemented to 100 wt%;

[0038] In step (2) of using drip irrigation, the mixed solution further includes an additive compound, and the mass concentration of the additive compound in the mixed solution is 1 wt% to 5 wt%;

[0039] The additive compound is selected from one or more of pyridine compounds and quaternary ammonium salt compounds.

[0040] Furthermore, the impregnation in step (2) is performed by pressurized impregnation or vacuum negative pressure impregnation;

[0041] The drying temperature in step (2) is 80° C. to 150° C., and the drying time is 5 min to 300 min.

[0042] Furthermore, the drying temperature in step (1) is 80° C. to 150° C. and the drying time is 5 min to 300 min;

[0043] Before forming the first wound body, the lead-out guide pins are riveted to the positive electrode foil and the negative electrode foil respectively; the formation in step (1) is to immerse the first wound body in a forming liquid, and then apply a forming voltage that is the same as the anode foil voltage of the first wound body, and the forming liquid is used to repair and form a new dielectric aluminum oxide film. The forming liquid can use one or more of an aqueous solution of ammonium dihydrogen phosphate, an aqueous solution of ammonium borate, an aqueous solution of boric acid, and an aqueous solution of ammonium adipate.

[0044] Furthermore, step (3) further comprises immersing the third wound body in an electrolyte, and immersing the third wound body in the electrolyte for 5 minutes to 10 minutes using a relative negative pressure of -90 KPa;

[0045] In step (3), when the electrolyte is used, the electrolytic capacitor is a solid-liquid hybrid electrolytic capacitor; otherwise, the electrolytic capacitor is a solid electrolytic capacitor.

[0046] Beneficial technical effects:

[0047] The present invention includes solid-state capacitors and solid-liquid hybrid capacitors. Unlike traditional capacitors, the present invention uses an n-type conductive polymer as the capacitor's electrolyte. The n-type conductive polymer has good solution processing performance and can be configured into solutions of different concentrations, with high production adaptability. It acts as a negative electrode in the capacitor. Since the main chain of the n-type conductive polymer used is negatively charged, it is more compatible with the capacitor's negative electrode. The n-type conductive polymer has an electrical conductivity of 500S / cm to 8000S / cm. As the capacitor's negative electrode, it conducts electricity through electrons, resulting in a capacitor with high capacitance and low ESR. In addition, the n-type conductive polymer has high air thermal stability, is not prone to dedoping reactions, and is not easily decomposed at high temperatures. The capacitor can maintain high capacitance and low ESR after 4000 hours of operation under double 85 conditions, showing good stability. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. Technology and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and methods should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments can have different values.

[0050] In addition, it should be noted that the use of words such as "first" and "second" to describe the winding body is only for the convenience of distinguishing the winding bodies in each preparation step. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0051] In the following examples, experimental methods without specific conditions are generally measured according to national standards. If there are no corresponding national standards, they are measured according to the general international standards or the standards proposed by relevant companies. Unless otherwise stated, all parts are by weight and all percentages are by weight.

[0052] The raw material 3,7-dihydrobenzo[1,2-b:4,5-b']dithiophene-2,6-dione used in the following examples was prepared according to the methods disclosed in Chemistry Letters, 1983, 905-908 and Organic Electronics, 2016, 35, 41-46; the CAS number of the raw material 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione used is 30272-74-3.

[0053] Example 1

[0054] An electrolytic capacitor based on an n-type conductive polymer is prepared by impregnating a DMSO solution of the n-type conductive polymer to prepare a 16V 470μF 6.3×11 solid-state capacitor. The preparation process of the solid-state capacitor includes the following steps:

[0055] (1) Cutting the positive electrode foil, electrolytic paper, and negative electrode foil to corresponding widths, and winding the positive electrode foil, electrolytic paper, and negative electrode foil in sequence into a first winding body of required specifications, butt-welding the first winding body on a stainless steel bar, and then placing it in a conversion liquid for conversion treatment, taking it out and drying it, repeating the above "first conversion treatment, then drying treatment" process twice to obtain a second winding body; wherein the conversion treatment is to immerse the first winding body in the conversion liquid, and then apply a conversion voltage of 25VF, and the conversion liquid is used to repair and form a new dielectric aluminum oxide film. In this case, the conversion liquid is an aqueous solution of ammonium adipate with a mass concentration of 8%;

[0056] (2) placing the second wound body in an n-type conductive polymer solution, and using a hydraulic impregnation device to pressurize and impregnate the solution at room temperature under a pressure of 0.8 MPa for 10 minutes, followed by vacuum drying at 80°C for 150 minutes. Repeat the above steps of pressurizing and impregnating followed by vacuum drying twice to obtain a third wound body;

[0057] The n-type conductive polymer solution was prepared by the following method: 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 mmol) and oxidant duroquinone (1.5 mmol) were dissolved in 10 mL of dimethyl sulfoxide (DMSO). After vacuum degassing, the mixture was stirred at 80°C under a relative negative pressure of -0.08 MPa for 8 h. The solution was then diluted with DMSO to a solid content of approximately 15 mg / mL and dialyzed against a DMSO solution using a dialysis bag (molecular weight cutoff = 10 kDa). The remaining solution in the dialysis bag was the n-type conductive polymer solution (containing 1 wt% of n-type conductive polymer I and the remainder being DMSO). The reactions involved were as follows:

[0058] The number average molecular weight of the n-type conductive polymer I obtained by the above reaction is Mn =323kDa, the dispersion coefficient is 2.41, the average conductivity is 6400S / cm, and m in the structural formula is 0.7-0.9n; the hydrogen ions are brought by the hydrogen removed from the raw materials themselves and the water in the solvent or the environment;

[0059] (3) fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor;

[0060] The semi-finished capacitor is charged and aged to obtain a finished solid-state capacitor.

[0061] The performance of the solid-state capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0062] Example 2

[0063] An electrolytic capacitor based on an n-type conductive polymer is prepared by impregnating an N,N-dimethylacetamide (DMAc) solution of the n-type conductive polymer to prepare a 16V 470μF 6.3×11 solid-state capacitor. The preparation process of the solid-state capacitor includes the following steps:

[0064] Step (1) is the same as step (1) of Example 1;

[0065] (2) placing the second wound body in a sealed container containing an n-type conductive polymer solution and vacuum impregnating the solution. The vacuum degree during vacuum impregnation is 0.1 MPa, the impregnation temperature is 50° C., and the impregnation time is 20 min. The solution is then vacuum dried at 80° C. for 150 min. The above steps of vacuum impregnation followed by vacuum drying are repeated twice to obtain a third wound body.

[0066] The n-type conductive polymer solution was prepared by the following method: 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 mmol), 3,7-dihydrobenzo[1,2-b:4,5-b']dithiophene-2,6-dione (1 mmol) and copper acetate (0.1 mmol) as an oxidant were dissolved in 10 mL of DMAc, and the mixture was stirred at 65°C for 30 minutes under air atmosphere. The solution was then diluted with DMAc to a solid content of about 20 mg / mL, and filtered through a polytetrafluoroethylene filter membrane with a diameter of 0.22 μm to obtain an n-type conductive polymer solution (containing 2 wt% of n-type conductive polymer II and the balance being DMAc). The reaction involved is as follows:

[0067] The number average molecular weight M of the n-type conductive polymer II obtained by the above reaction is n=2468kDa, average conductivity is 1260S / cm, n1:n2≈1, m≈0.6(n1+n2), y≈0.05m, z≈0.01m;

[0068] (3) fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor;

[0069] The semi-finished capacitor is charged and aged to obtain a finished solid-state capacitor.

[0070] The performance of the solid-state capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0071] Example 3

[0072] An electrolytic capacitor based on an n-type conductive polymer is prepared by in-situ polymerization of the n-type conductive polymer monomer using step-by-step impregnation to produce a 16V 470μF 6.3×11 solid-state capacitor. The preparation process of the solid-state capacitor includes the following steps:

[0073] Step (1) is the same as step (1) of Example 1;

[0074] (2) 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 mmol) was dissolved in 5 mL of DMSO to obtain an n-type conductive polymer monomer solution, and manganese acetate (1 mmol) was dissolved in 5 mL of DMSO as an oxidant to obtain an oxidant solution;

[0075] The second wound body was placed in the above-mentioned n-type conductive polymer monomer solution and impregnated at room temperature and normal pressure for 10 minutes, then removed and vacuum dried at 80°C for 30 minutes; then placed in the above-mentioned oxidant solution and impregnated at room temperature and normal pressure for 2 minutes, then removed and vacuum dried at 80°C for 5 minutes; the steps of impregnation with the n-type conductive polymer monomer solution, vacuum drying, impregnation with the oxidant solution, and vacuum drying were repeated three times to obtain a third wound body, and the monomers were in situ polymerized under the above-mentioned sequence to obtain the corresponding n-type conductive polymer (the above in situ polymerization is a precipitation reaction, and its molecular weight cannot be measured, but the same reaction conditions can be used to obtain polymer powder. The average conductivity of the n-type conductive polymer obtained in this case was 680 S / cm as determined by powder tableting).

[0076] (3) fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor;

[0077] The semi-finished capacitor is charged and aged to obtain a finished solid-state capacitor.

[0078] The performance of the solid-state capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0079] Example 4

[0080] An electrolytic capacitor based on an n-type conductive polymer is disclosed. In this embodiment, a drip irrigation method is used to in-situ polymerize n-type conductive polymer monomers to prepare a 16V 470μF 6.3×11 solid-state capacitor. The preparation process of the solid-state capacitor includes the following steps:

[0081] Step (1) is the same as step (1) of Example 1;

[0082] (2) 3,7-Dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 mmol) and duroquinone oxidant (1.5 mmol) were dissolved in 5 mL of DMSO and stirred at 60°C for 30 minutes to obtain a monomer-oxidant mixed solution;

[0083] The monomer-oxidant mixed solution was injected into the second wound body using a quantitative syringe, and heated and polymerized at 80°C for 3 hours under a nitrogen atmosphere. Then, vacuum dried at 80°C for 30 minutes. The heating, polymerization, and vacuum drying steps were repeated twice to obtain a third wound body. The monomers were in situ polymerized according to the above steps to obtain the corresponding n-type conductive polymer (the molecular weight of the polymer obtained by the above in situ polymerization could not be measured, but the polymer powder was obtained under the same reaction conditions. The average conductivity of the n-type conductive polymer obtained in this case was 4200 S / cm as determined by tableting).

[0084] (3) Fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor; charging and aging the semi-finished capacitor to obtain a finished solid-state capacitor.

[0085] The performance of the solid-state capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0086] Example 5

[0087] An electrolytic capacitor based on an n-type conductive polymer is disclosed. In this embodiment, a drip irrigation method is used to in-situ polymerize the n-type conductive polymer monomer. During polymerization, additives can form counterions for the conductive polymer. This is used to prepare a 16V 470μF 6.3×11 solid-state capacitor. The preparation process for this solid-state capacitor includes the following steps:

[0088] Step (1) is the same as step (1) of Example 1;

[0089] (2) 3,7-Dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 mmol), duroquinone (1.5 mmol) as an oxidant, and 1-ethylpyridinium bromide (1 mmol) as an additive were dissolved in 5 mL of DMSO and stirred at 60°C for 30 minutes to obtain a monomer-oxidant-additive mixed solution;

[0090] The mixed solution was injected into the second wound body using a quantitative syringe, and heated and polymerized at 80°C for 3 hours under a nitrogen atmosphere, followed by vacuum drying at 80°C for 30 minutes. The heating, polymerization, and vacuum drying steps were repeated twice. The chemical reaction formula involved is as follows:

[0091] The molecular weight of the polymer obtained by in situ polymerization cannot be measured, but the same reaction conditions can be used to obtain polymer powder. The average conductivity of the n-type conductive polymer III obtained in this case was 1800 S / cm through tablet testing, where m≈0.8n and y≈0.7m.

[0092] (3) Fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor; charging and aging the semi-finished capacitor to obtain a finished solid-state capacitor.

[0093] The performance of the solid-state capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0094] Comparative Example 1

[0095] This comparative example provides a method for preparing a 16V 470μF 6.3×11 solid-state capacitor using a p-type conductive polymer PEDOT:PSS dispersion. The preparation method is as follows:

[0096] Step (1) is the same as step (1) of Example 1;

[0097] (2) using a commercially available PEDOT:PSS aqueous solution, wherein the mass fraction of PEDOT:PSS is in the range of 1% to 3%, and the diameter of the solid matter particles in the dispersion is not greater than 100 nm; using a hydraulic impregnation device to place the second wound body into the PEDOT:PSS aqueous solution for pressure impregnation, the impregnation conditions being the same as those in step (2) of Example 1; repeating the above steps of first pressurizing impregnation and then vacuum drying twice to obtain a third wound body;

[0098] Step (3) is the same as step (3) of Example 1;

[0099] The performance of the solid-state capacitor obtained in this comparative example was tested, and the test results are shown in Table 1.

[0100] Example 6

[0101] An electrolytic capacitor based on an n-type conductive polymer is prepared by impregnating a DMSO solution of an n-type conductive polymer to prepare a 16V 470μF 6.3×11 solid-liquid hybrid capacitor. The preparation process of the solid-liquid hybrid capacitor includes the following steps:

[0102] Steps (1) and (2) are the same as steps (1) and (2) of Example 1;

[0103] (3) placing the third wound body into a sealed container containing an electrolyte for vacuum impregnation at a relative negative pressure of -90 kPa for 10 minutes; the electrolyte formulation is: 15 wt% ethylene glycol, 50 wt% γ-butyrolactone, 15 wt% sulfolane, and 20 wt% tetrabutylammonium hexafluorophosphate;

[0104] The third winding body impregnated with the electrolyte is fixed in an aluminum shell, assembled and sealed to obtain a semi-finished capacitor; the semi-finished capacitor is charged and aged to obtain a finished solid-liquid hybrid capacitor.

[0105] The performance of the solid-liquid hybrid capacitor obtained in this embodiment was tested, and the test results are shown in Table 1.

[0106] Example 7

[0107] An electrolytic capacitor based on an n-type conductive polymer is prepared by impregnating a DMSO solution of the n-type conductive polymer to prepare a 2.5V 1.1mF 6.3×8 solid-state capacitor. The preparation process of the solid-state capacitor includes the following steps:

[0108] Step (1) is the same as step (1) of Example 1;

[0109] (2) The n-type conductive polymer solution prepared in step (2) of Example 1 (containing n-type conductive polymer I at a concentration of 1 wt % and the balance being DMSO) was diluted with DMSO to a solid content of 0.5 wt %, and the diluted solution was homogenized using a homogenizer to obtain an n-type conductive polymer solution with a solid content of 0.5 wt %;

[0110] The second wound body was placed in a sealed container containing an n-type conductive polymer solution (solid content of 0.5 wt%) and vacuum impregnated at a vacuum degree of 0.1 MPa, an impregnation temperature of 50° C., and an impregnation time of 5 minutes. The second wound body was then vacuum dried at 80° C. for 150 minutes. The above vacuum impregnation followed by vacuum drying was repeated twice to obtain a third wound body.

[0111] (3) Fixing the third winding body in an aluminum shell, assembling and sealing it to obtain a semi-finished capacitor; charging and aging the semi-finished capacitor to obtain a finished solid-state capacitor.

[0112] Test Case

[0113] The capacitors made from n-type conductive polymers in the examples and the solid-state capacitors made from p-type conductive polymer PEDOT:PSS in the comparative examples were subjected to relevant electrical performance tests. Capacitance (CAP), loss tangent (DF), equivalent series resistance (ESR), and leakage current (LC) were tested in accordance with GB / T6346.25-2018, "Fixed Capacitors for Electronic Equipment - Part 25: Sectional Specification for Surface-Mounted Conductive Polymer Solid Electrolyte Aluminum Fixed Capacitors." The capacitance and loss tangent were tested at 20°C and 120Hz, the equivalent series resistance at 20°C and 100Hz, and the leakage current at 20°C and 2 minutes. The initial performance of the capacitors is shown in Table 1. The capacitors from the examples and comparative examples were then tested for electrical performance after operating continuously for 1000-4000 hours at 85°C and 85% humidity (double 85 conditions). The test results are detailed in Table 2.

[0114] Table 1 Initial performance of capacitors of embodiment and comparative example

[0115] Table 2 Performance of capacitors in the embodiment and comparative example under double 85 continuous working conditions for different time periods

[0116] As can be seen from Tables 1 and 2, when Example 1 is compared with Comparative Example 1, the solid-state or solid-liquid hybrid capacitor prepared using the n-type conductive polymer of the present invention has a relatively higher capacity extraction rate than the capacitor prepared using the p-type conductive polymer PEDOT, and the high-frequency ESR value is also significantly reduced. This is because the preparation method based on the n-type conductive polymer of the present invention can make the capacitor completely impregnated, and the n-type conductive polymer has a higher conductivity than the p-type; more importantly, the solid-state or solid-liquid hybrid capacitor prepared using the n-type conductive polymer of the present invention has more stable device performance under dual 85 conditions, which is beneficial to extending the service life of the capacitor under extreme conditions.

[0117] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An electrolytic capacitor based on an n-type conductive polymer, comprising a winding body formed by stacking a negative electrode foil, an electrolytic paper, and a positive electrode foil with an oxide film dielectric formed on the surface in sequence; Features: The winding body has an n-type conductive polymer electrolyte layer; The material of the n-type conductive polymer electrolyte layer includes one or more n-type conductive polymers, and the n-type conductive polymer has the following repeating units with negatively charged conjugated structures: wherein X is one of oxygen, sulfur, selenium, tellurium and nitrogen; when X is nitrogen, R is one of hydrogen, linear alkyl and isomeric alkyl; when X is one of oxygen, sulfur, selenium and tellurium, R is absent; Y + represents a cation; the repeating units of the negatively charged conjugated structure are the same or different.

2. An electrolytic capacitor based on n-type conductive polymer according to claim 1, characterized in that: The conductivity of the n-type conductive polymer is 500 S / cm to 8000 S / cm; the molecular weight of the n-type conductive polymer is at least 1 kDa; The cation is selected from one or more of hydrogen ions, quaternary ammonium ions, pyridinium ions, and metal ions.

3. An electrolytic capacitor based on n-type conductive polymer according to claim 1 or 2, characterized in that: The electrolytic capacitor further includes an electrolyte for impregnating the wound body, a case for accommodating the wound body and the electrolyte, and a sealing member for sealing the case.

4. The electrolytic capacitor based on n-type conductive polymer according to claim 3, characterized in that: The housing is made of metal; The electrolytic paper is selected from artificial fibers and / or natural fibers; The positive electrode foil and the negative electrode foil are respectively made of aluminum valve metal; and lead-out guide pins are respectively provided on the positive electrode foil and the negative electrode foil.

5. A process for preparing an electrolytic capacitor based on an n-type conductive polymer according to any one of claims 1 to 4, characterized in that: The following steps are included: (1) winding a positive electrode foil, an electrolytic paper, and a negative electrode foil in sequence into a first winding body of required specifications, subjecting the first winding body to at least one chemical formation treatment, wherein the chemical formation treatment includes chemical formation followed by drying, to obtain a second winding body; (2) forming an electrolyte layer having the n-type conductive polymer in the second wound body to obtain a third wound body; (3) After being placed in a housing and sealed, the product is powered on for aging, thereby obtaining an electrolytic capacitor based on an n-type conductive polymer.

6. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 5, characterized in that: The process of step (2) forming an electrolyte layer having the n-type conductive polymer is: placing the second winding body in an n-type conductive polymer solution for at least one impregnation treatment, the impregnation treatment comprising first impregnation and then drying; the n-type conductive polymer solution contains one or more of the n-type conductive polymers.

7. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 6, characterized in that: The n-type conductive polymer solution contains 0.1 wt% to 10 wt% of the n-type conductive polymer and an organic solution; The organic solvent is selected from one or more of aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, amines, esters, ethers, ketones, dimethyl sulfoxide, amides, and sulfolane.

8. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 5, characterized in that: The process of forming the electrolyte layer having the n-type conductive polymer in step (2) is as follows: the second winding body is subjected to the steps of impregnation with an n-type conductive polymer monomer solution, drying, impregnation with an oxidant solution, and drying at least once in a step-by-step impregnation manner to obtain a third winding body, wherein the n-type conductive polymer monomer solution contains one or more n-type conductive polymer monomers; Alternatively, the process of forming the electrolyte layer having the n-type conductive polymer in step (2) is: dripping a mixed solution containing one or more n-type conductive polymer monomers and an oxidant into the second winding body at least once by drip irrigation, then heating and polymerizing the mixed solution at least once, and then drying the mixed solution to obtain a third winding body; The n-type conductive polymer monomer has the following structure: Wherein X is one of oxygen atom, sulfur atom, selenium atom, tellurium atom and nitrogen atom; when X is nitrogen atom, R is one of hydrogen atom, linear alkyl group and isomeric alkyl group; when X is one of oxygen atom, sulfur atom, selenium atom and tellurium atom, R does not exist.

9. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 8, characterized in that: In step (2) of adopting the stepwise impregnation method, the n-type conductive polymer monomer solution contains 0.1wt% to 5wt% of the n-type conductive polymer monomer and an organic solution; the oxidant solution contains 0.1wt% to 10wt% of an oxidant and an organic solution; The heating polymerization in step (2) of the drip irrigation method is carried out at 50° C. to 150° C. under nitrogen protection; wherein the mixed solution containing one or more n-type conductive polymer monomers and an oxidant comprises the n-type conductive polymer monomer, the oxidant and an organic solution, the mass concentration of the n-type conductive polymer monomer is 1wt% to 5wt%, and the mass concentration of the oxidant is 1wt% to 5wt%; The oxidant is selected from one or more of oxygen, peroxide, metal salt, persulfate, perborate, hypohalite, quinone compound, and perbenzoic acid; the organic solution is selected from one or more of aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, amines, esters, ethers, ketones, dimethyl sulfoxide, amides, and sulfolane.

10. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 9, characterized in that: In step (2) of adopting the stepwise impregnation method, after the steps of impregnating and drying the oxidant solution, an impregnation step of an additive compound solution is also included, wherein the additive compound solution contains an additive compound; The mixed solution in step (2) of using drip irrigation also includes an additive compound; The additive compound includes one or more of pyridine compounds and quaternary ammonium salt compounds.

11. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 6 or 8, characterized in that: The impregnation in step (2) is performed by pressurized impregnation or vacuum negative pressure impregnation; The drying temperature in step (2) is 80° C. to 150° C. and the drying time is 5 min to 300 min.

12. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 5, characterized in that: The drying temperature in step (1) is 80°C to 150°C and the drying time is 5min to 300min; Before forming the first winding body, the lead-out guide pins are riveted to the positive electrode foil and the negative electrode foil respectively; the formation in step (1) is to immerse the first winding body in a formation liquid, and then apply a formation voltage that is the same as the anode foil voltage of the first winding body.

13. The process for preparing an electrolytic capacitor based on an n-type conductive polymer according to claim 5, characterized in that: Step (3) further comprises immersing the third wound body in an electrolyte, and immersing the third wound body in the electrolyte for 5 minutes to 10 minutes using a relative negative pressure of -90 KPa.

Images