Wet electrolytic capacitor containing gelling working electrolyte

Abstract

The invention provides a wet electrolytic capacitor. The capacitor comprises an anode, a cathode, and a working electrolyte in communication with the anode and the cathode, the anode comprising an anodized tablet formed from a pressed and sintered powder. The working electrolyte is in the form of a gel and includes an ammonium salt of an organic acid, inorganic oxide particles, a gelation activator, an acid, and a solvent system including water. The working electrolyte has a pH value of from about 5.0 to about 8.0.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 401,361, filed on August 26, 2022, which is incorporated herein by reference. Background Art

[0003] High voltage electrolytic capacitors are used as energy storage devices in many applications including implantable medical devices. These capacitors need to have a high energy density because it is necessary to minimize the overall size of the implantable device. This is especially true for implantable cardioverter defibrillator ("ICD"), also known as implantable defibrillator, because the high voltage capacitor used to transmit the defibrillation pulse can occupy one-third of the volume of the ICD. Typically, metal foil (e.g., aluminum foil) is used for electrolytic capacitors due to its small size. Because the electrostatic capacitance of a capacitor is proportional to its electrode area, the surface of the metal foil can be roughened or chemically converted to increase its effective area before forming the dielectric film. The capacitance of an electrolytic capacitor depends on the roughness (surface area) of the anode foil and the thickness and dielectric constant of the oxide film.

[0004] Due to the limited surface area available by etching the metal foil, attempts have also been made to use porous sintered pellets in wet electrolytic capacitors - i.e., "wet tantalum" capacitors. For example, tantalum pellets can be formed by compressing a powder under high pressure and sintering at high temperature to form a sponge-like structure that is very strong and dense, but also has a high porosity. The porosity of the resulting tantalum pellet provides a large internal surface area. However, despite its high surface area, tantalum pellets may still exhibit high DCL and sensitivity of capacitance to frequency, particularly at high voltages often encountered in medical devices. Further attempts have been made to overcome these problems using gelled electrolytes. However, gelled electrolytes exhibit instability or degradation within the capacitor, as well as unpredictable gelation times. That is, it has proven difficult to provide a gelled electrolyte that can gel within the time required for production while maintaining good electrical properties and without the use of external energy or catalysis.

[0005] Therefore, there is a need for an improved wet electrolytic capacitor for use in implantable medical devices, such as defibrillators. Summary of the invention

[0006] According to one aspect of the present disclosure, a wet electrolytic capacitor is disclosed, the wet electrolytic capacitor comprising an anode, a cathode, and a working electrolyte connected to the anode and the cathode, the anode comprising an anodic oxide pressed sheet formed by pressed and sintered powder. The working electrolyte is in gel form and has a pH value of about 5.0 to about 8.0. In addition, as measured at a temperature of 37°C and a rated voltage (e.g., 282V in an example as discussed below), the wet electrolytic capacitor exhibits a leakage current (DCL) of about 625 micro-ohms or less.

[0007] According to another aspect of the present disclosure, a working electrolyte for a wet electrolytic capacitor is disclosed. The electrolyte includes about 1 wt.% to about 40 wt.% of at least one organic acid ammonium salt, about 0.01 wt.% to about 10 wt.% of at least one acid, about 0.5 wt.% to about 20 wt.% of inorganic oxide particles, about 0.01 wt.% to about 1 wt.% of a gelling activator, about 30 wt.% to about 80 wt.% of water, and about 5 wt.% to about 40 wt.% of at least one co-solvent (secondary solvent). The working electrolyte is in the form of a gel and has a pH value of about 5.0 to about 8.0, and the working electrolyte has a conductivity of about 10 millisiemens / cm to about 100 millisiemens / cm measured at a temperature of 25°C.

[0008] According to another aspect of the present disclosure, a method for forming a wet electrolytic capacitor is disclosed. The method includes: forming a mixture, the mixture comprising an ammonium salt of an organic acid, inorganic oxide particles, a gelling activator, an acid, and a solvent system including water; inducing gelation of the mixture so that the mixture exhibits a first phase angle δ of about 50° to 90°; connecting the gelled mixture to an anode, a cathode, or both, wherein the anode is an anodized pressed sheet formed from a pressed and sintered powder; then, further gelling the mixture to form a working electrolyte, the working electrolyte exhibiting a second phase angle δ of 0° to about 20°, wherein the working electrolyte exhibits the second phase angle during about 18 hours or less, and the working electrolyte also has a pH value of about 5.0 to about 8.0.

[0009] Other features and aspects of the present invention are described in more detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The remainder of this specification more particularly describes a complete and enabling disclosure of the present invention (including the best mode thereof) for one of ordinary skill in the art with reference to the accompanying drawings, in which:

[0011] Figure 1is a perspective view of an embodiment of a wet electrolytic capacitor of the present invention;

[0012] Figure 2 is a top view of an embodiment of an anode that can be used in a capacitor of the present invention;

[0013] Figure 3 yes Figure 2 A front view of an anode of; and

[0014] Figure 4 Yes Description Figure 2 The anode and the casing component are assembled to form Figure 1 A perspective view of the capacitor shown.

[0015] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

[0016] definition

[0017] As used herein, when used to modify a value, the term "about", "approximately" or "generally" means that the value can be increased or decreased by 10% and remain within the disclosed aspects, such as 7.5%, such as 5%, such as 4%, such as 3%, such as 2%, such as 1%, or any range or value therebetween. In addition, when used to describe the amount of a substance in a material, the term "substantially free" is not limited to being completely or completely absent, and may correspond to the lack of any perceptible or detectable amount of the substance in the material. Thus, for example, when the amount of a substance in a material is less than the precision of an instrument or test recognized by industry for measuring the amount of a substance in a material, the material is "substantially free" of the substance. In certain example embodiments, when the amount of a substance in a material is less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5% or less than 0.1% by weight, the material may be "substantially free" of the substance. DETAILED DESCRIPTION

[0018] Those skilled in the art will appreciate that the present discussion is merely a description of exemplary aspects and is not intended to limit the broader aspects of the invention, which are embodied in the exemplary constructions.

[0019] The present disclosure relates to a wet electrolytic capacitor comprising an anodic oxidized porous anode body, a cathode and a working electrolyte, which is an electroactive material that provides a connection path between the anode and the cathode. The working electrolyte has a neutral pH and exists in the form of a viscoelastic gel, which helps to chemically stabilize the electrolyte and improve the wetting uniformity of the anode-cathode interface. Contrary to conventional wisdom, the capacitor of the present invention can be formed from such a gel and still achieve relatively high capacitance and energy density without exhibiting high equivalent series resistance (ESR) and / or DC leakage current (DCL). Without being limited by theory, the inventors believe that this unique combination of electrical properties can be achieved by selectively controlling various aspects of the working electrolyte. For example, the working electrolyte includes an ammonium salt of an organic acid, inorganic oxide particles, an acid, a gelling activator and an aqueous solvent system. When used in appropriate concentrations, the combination of these ingredients can produce a gelled electrolyte, but still have high conductivity and a neutral pH.

[0020] That is, the inventors surprisingly discovered that by carefully controlling the amount of certain gelling activators, the gelling time can be carefully and meticulously regulated while maintaining excellent electrical properties. Without being bound by theory, the inventors believe that even small amounts of specific gelling activators can initiate crosslinking and / or self-assembly between individual gelling activator particles and between inorganic oxide particles contained in the working electrolyte, so that customized amounts of gelling activators can be used in combination with inorganic oxide particles to prepare working electrolytes having narrow gelling time ranges and excellent electrical properties (including high conductivity and low leakage current). Surprisingly, the inventors have discovered that gelling can be initiated even with small amounts of gelling activators without the need for strong acids, high temperatures, or controlled energy typically required for gelling with inorganic oxide particles.

[0021] For example, in one aspect, the working electrolyte according to the present invention exhibits a gelation time (the phase angle of the specific viscosity and the gelation time (also referred to as the gelation phase angle) will be discussed in more detail below) of about 80 hours or less, such as about 72 hours or less, such as about 60 hours or less, such as about 48 hours or less, such as about 36 hours or less, such as about 24 hours or less, such as about 22 hours or less, such as about 20 hours or less, such as about 18 hours or less, such as about 16 hours or less, such as about 14 hours or less, such as about 12 hours or less, such as about 5 minutes or more, such as about 15 minutes or more, such as about 30 minutes or more, such as about 45 minutes or more, such as about 1 hour or more, such as about 2 hours or more, such as about 4 hours or more, such as about 6 hours or more, such as about 8 hours or more, or any value or range therebetween. For example, in one aspect, the gelation time can be tailored to between about 2 hours to about 20 hours, such as between about 4 hours to about 18 hours, such as between about 6 hours to about 12 hours, or any range or value therebetween. That is, as described above, by employing the gelation described herein, a working electrolyte having a highly specific gelation time can be formed, which can improve the stability of the formed capacitor, as well as improve the impregnation of the anode and / or cathode, at least in part due to the improved processing predictability of the working electrolyte.

[0022] In addition, the above-mentioned gelation time can be exhibited without high temperature, such as solidifying in any one or more time periods of the above-mentioned time periods at room temperature (23°C). However, on the one hand, according to the present disclosure, the gelation time can be further adjusted using an elevated temperature. Therefore, on the one hand, the gelation according to any one or more of the above-mentioned time periods or ranges can be carried out at a temperature of less than 100°C, such as about 90°C or lower, such as about 80°C or lower, such as about 70°C or lower, such as about 60°C or lower, such as about 50°C or lower, such as about 40°C or lower, such as about 30°C or lower, or any range or value therebetween. Of course, as described above, on the one hand, gelation is carried out at room temperature without heating.

[0023] In addition, the inventors have found that the gelation time can be adjusted even with a very small amount of gelation activator. In one aspect, the content of the gelation activator in the working electrolyte is about 0.01 wt.% or more, such as about 0.02 wt.% or more, such as about 0.03 wt.% or more, such as about 0.04 wt.% or more, such as about 0.05 wt.% or more, such as about 0.06 wt.% or more, such as about 0.07 wt.% or more, such as about 0.08 wt.% or more, such as about 0.09 wt.% or more, such as about 0.1 wt.% or more, based on the weight of the working electrolyte. Such as about 0.2wt.% or more, such as about 0.25wt.% or more, such as up to about 2wt.% or less, such as about 1.75wt.% or less, such as about 1.5wt.% or less, such as about 1.25wt.% or less, such as about 1wt.% or less, such as about 0.9wt.% or less, such as about 0.8wt.% or less, such as about 0.7wt.% or less, such as about 0.6wt.% or less, such as about 0.5wt.% or less, or any range or value therebetween. For example, on the one hand, based on the weight of the working electrolyte, the content of the gelling activator in the working electrolyte is about 0.01wt.% to about 2wt.%, such as about 0.05wt.% to about 0.1wt.%, or any range or value therebetween.

[0024] In addition, as described above, it has been found that capacitors formed according to the present disclosure maintain or even improve electrical performance while improving gelation time without an external energy source, compared to capacitors that do not include a gelation activator. For example, as measured at a temperature of 37° C. and a rated voltage, leakage current (DCL) (generally referring to the current flowing from one conductor to an adjacent conductor through an insulator) can be maintained at a relatively low level, such as about 650 micro-ohms or less, such as about 625 micro-ohms or less, such as about 600 micro-ohms or less, such as about 575 micro-ohms or less, such as about 550 micro-ohms or less, such as about 525 micro-ohms or less, such as about 500 micro-ohms or less, or any range or value therebetween. After a charging time of about 60 seconds to about 300 seconds, the leakage current can be measured using a leakage tester (e.g., a Keithley 2400 Series Source Meter) at a temperature of 37° C. and a certain rated voltage (e.g., in an example described below, such as 282V). The equivalent series resistance (ESR) - the degree to which a capacitor acts as a resistor when charged and discharged in an electronic circuit - measured with a 2 volt bias and a 1 volt signal at a frequency of 120 Hz can also be about 15,000 milliohms or less, such as about 10,000 milliohms or less, such as about 5,000 milliohms or less, such as about 1 milliohm to about 4,500 milliohms.

[0025] Surprisingly, such ESR and leakage current values ​​can be maintained even after aging alone or together with high temperature for a considerable period of time. Without being bound by theory, the inventors have found that the gelled electrolyte as described herein is highly resistant to degradation, such as by preventing the occurrence of "bare spots" of voids between the anode and cathode. That is, such a gelled electrolyte provides a more reliable gelation of the gelled electrolyte, thereby forming a more uniform and stable gel that maintains excellent electrical properties even during a considerable period of use. For example, at room temperature alone, or even at a temperature in the range of about 100°C to about 250°C (in some embodiments, at a temperature in the range of about 100°C to about 200°C (e.g., 100°C, 125°C, 150°C, 175°C, or 200°C)), the leakage current value and / or ESR value can be maintained for about 100 hours or longer, in some embodiments from about 300 hours to about 2500 hours, and in some embodiments from about 400 hours to about 1500 hours (e.g., 500 hours, 600 hours, 700 hours, 800 hours, 900 hours, 1000 hours, 1100 hours, or 1200 hours).

[0026] The highly conductive gelled electrolyte can also work synergistically with the cathode system to achieve the desired electrical properties. Without being limited by theory, the inventors believe that charging the capacitor to a high voltage (e.g., greater than the formation voltage) can increase the charge density. Still, since the conductive polymer is generally amorphous, it can dissipate and / or absorb the heat associated with the high voltage. During discharge, the conductive polymer also "relaxes" and allows ions in the electrolyte to move out of the polymer layer. Through this expansion and relaxation mechanism, the charge density near the electrode can be increased without chemically reacting with the electrolyte.

[0027] Various embodiments of the invention will now be described in further detail.

[0028] 1. Working electrolyte electrolytes

[0029] As described above, the working electrolyte is in the form of a viscoelastic "gel", which is generally defined as a solid or semi-solid colloidal suspension comprising a continuous phase and a dispersed phase, wherein at least one of the phases is solid and at least one of the phases is liquid. For example, when the gelling activator and the inorganic oxide particles are crosslinked or self-assembled to form a continuous phase, a hydrogel can be formed, and the solvent comprises water as a dispersed phase, which is trapped in the crosslinked and / or self-assembled network structure. Regardless of its specific form, the viscoelastic gel in the capacitor is in the form of a semi-solid or solid state, so it is not easy to flow at room temperature. This property can be represented by the phase angle δ of viscoelasticity, which is the degree of phase difference between the sinusoidal time variation of stress and the sinusoidal time variation of shear rate. The phase angle δ of an ideal elastic solid is 0° (in phase), and the phase angle δ of an ideal viscous liquid is 90° (out of phase). In the present invention, the phase angle δ exhibited by the gelled electrolyte is generally 0° to about 20°, in some embodiments about 0.1° to about 5°, and in some embodiments about 0.2° to about 2°. Another parameter that can characterize the viscoelastic behavior of the gel is the storage modulus G', which is determined by dividing the "in-phase" component of the stress (representing solid-like behavior) by the maximum strain. The storage modulus exhibited by the gelled electrolytes of the present invention is typically about 5 kilopascals (KPa) or greater, in some embodiments about 10 kPa or greater, and in some embodiments about 15 kPa to about 50 kPa. The phase angle and storage modulus can be determined at room temperature (e.g., 25°C) by dynamic oscillation testing (e.g., frequency of 10 Hz, pressure of 5 Pa) using a rheometer with a cone-plate configuration.

[0030] The conductivity of the working electrolyte is high, measured at a temperature of 25° C. using any known conductivity meter (e.g., Oakton Con Series 11 conductivity meter), and the conductivity is generally in the range of about 10 millisiemens per centimeter (“mS / cm”) to about 100 millisiemens per centimeter (“mS / cm”), in some embodiments in the range of about 20 mS / cm to about 90 mS / cm, and in some embodiments in the range of about 24 mS / cm to about 80 mS / cm. Within the above range, the electric field is as strong as the dielectric, but can extend into the electrolyte to a length (Debye length) sufficient to cause significant charge separation. This extends the potential energy of the dielectric into the electrolyte, allowing the formed capacitor to store more potential energy than would be predicted by the thickness of the dielectric. In other words, the capacitor can be charged to a voltage approaching or even exceeding the formation voltage of the dielectric. The ratio of the voltage to which the capacitor can be charged to the formation voltage can be, for example, about 0.80 to about 2.00, about 0.85 to about 1.50 in some embodiments, and about 0.86 to about 1.20 in some embodiments. For example, the voltage to which the capacitor can be charged can be about 150V to about 500V, about 180V to about 260V in some embodiments, and about 200V to about 240V in some embodiments. Similarly, the range of the formation voltage can be about 180V to about 320V, about 200V to about 280V in some embodiments, and about 220V to about 250V in some embodiments. The working electrolyte is also neutral and therefore has a pH value of about 5.0 to about 8.0, about 5.5 to about 7.5 in some embodiments, and about 6.0 to about 7.0 in some embodiments. Among other factors, such pH can enhance the ability of the hydrogen ions present in the aqueous electrolyte to interact with the cathode material, thereby achieving maximum capacitance and energy density.

[0031] To achieve a combination of high conductivity and neutral pH, the working electrolyte comprises a combination of a certain concentration of ammonium salt, inorganic oxide particles, acid, gelling activator and solvent system. The properties and concentrations of these components are selectively controlled to help achieve the desired electrical properties of the capacitor. In this regard, various embodiments of the components of the electrolyte will now be described in more detail below.

[0032] A. Gelating activator activator)

[0033] The gelling activator can be present in any content as discussed above. On the one hand, the gelling activator can be a self-assembling gelator, a cross-linking gelator or a combination thereof. That is, as described above, in the case of also being applicable to implantable medical devices, a suitable gelling activator should have sufficient activity to initiate crosslinking and / or self-assembly between the gelling activator and between the inorganic oxide particles. Therefore, it should be clear from the discussion herein that the gelling activator is a compound that can initiate gelling in the absence of external energy, and is different from the inorganic oxide particles discussed herein.

[0034] For example, on the one hand, as will be discussed in more detail below, cross-linked gelling agent can be selected to form a cross-linked network between each gelation activator particle and / or between inorganic oxide particles. That is to say, the cross-linking between each particle forms a gel, and this gel retains the liquid phase of the electrolyte. Similarly, self-assembly gelling agent (such as amphipathic self-assembly gelling agent) can self-assemble so that the hydrophobic part and the hydrophilic part of the self-assembly gelling agent interact, thereby retain the liquid phase of the electrolyte, and form gel by the self-assembled structure. In addition, as mentioned above, surprisingly found that self-assembly gelling agent and / or cross-linked gelling agent can form a structure comprising inorganic oxide particles, without sacrificing gel structure, thereby allowing the use of a very small amount of gelling agent to form a stable gel.

[0035] Therefore, in one aspect, suitable gelling activators may include: sugar or its derivatives, vitamins or their derivatives, glycerol or its derivatives, or a combination thereof and C 1 -C 36 Fatty C 1 -C 36 An ester formed from an alkanoic acid; an organometallic compound; or any combination of an ester and an organometallic compound. Suitable organometallic compounds may have the general formula:

[0036]

[0037] in,

[0038] M is an organometallic atom, such as silicon, titanium, etc. In one aspect, M is silicon;

[0039] R 1 , R 2 and R 3 are independently alkyl (e.g., methyl, ethyl, propyl, etc.) or hydroxyalkyl (e.g., hydroxymethyl, hydroxyethyl, hydroxypropyl, etc.), wherein R 1 , R 2 and R 3 At least one of them is a hydroxyalkyl group;

[0040] n is an integer from 0 to 8, in some embodiments an integer from 1 to 6, and in some embodiments an integer from 2 to 4 (e.g., 3); and

[0041] X is an organic functional group or an inorganic functional group, such as a glycidyl group, a glycidyloxy group, a mercapto group, an amino group, a vinyl group, and the like.

[0042] In some aspects, R in formula (II) 1 , R 2 and R 3 At least one of the 3 ). For example, R 1 , R 2 and R 3 Each of R may be a hydroxyalkyl group. However, in other embodiments, R 1 It can be an alkyl group (e.g., CH 3 ), and R 2 and R 3 It can be a hydroxyalkyl group (e.g., OCH 3 ).

[0043] In yet another aspect, X can be an amino group. Suitable amino-functional organosilane compounds can include, for example, monoamino-functional silanes having the general formula:

[0044]

[0045] in,

[0046] R 1 , R 2 and R 3 As defined above;

[0047] R 4 and R 5 are independently hydrogen, alkyl, independently alkyl, alkenyl, aryl, heteroaryl, cycloalkyl, heterocyclyl, halogen, haloalkyl, hydroxyalkyl, or alternatively, N, R 4 and R 5 Together with one or more additional atoms, form a ring structure (e.g., heteroaryl or heterocyclyl); and

[0048] Z is an organic group that connects the nitrogen atom to the silicon atom, such as an alkyl group (eg, ethyl or propyl), an aryl group (eg, phenyl), or the like.

[0049] Examples of monoaminofunctional organosilane compounds may include, for example, primary amine compounds (e.g., 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltri(methoxy-ethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, etc.); secondary amine compounds (e.g., 3-aminopropyltriethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltri(methoxy-ethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, etc.); Amine compounds (for example, N-butylaminopropyltrimethoxysilane, N-ethylaminoisobutyltrimethoxysilane, n-methylaminopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, 3-(N-allylamino)propyltrimethoxysilane, cyclohexylaminomethyl)triethoxysilane, N-cyclohexylaminopropyltrimethoxysilane, N-ethylaminoisobutylmethyldiethoxysilane, (phenylaminoethyl)methyl-diethoxysilane, N-phenylaminomethyltrimethoxysilane, N-methylaminopropylmethyl-dimethoxysilane, etc.); tertiary amine compounds (for example, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, diethylaminomethyltriethoxysilane, (N,N-diethyl-3-aminopropyl)trimethoxysilane, etc.); and combinations thereof.

[0050] In addition, the gelling activator may be only the organometallic compound as described above, or in addition to the organometallic compound as described above, the gelling activator may also be sugar or its derivatives, vitamins or their derivatives, glycerol or its derivatives, or a combination thereof and C 1 -C 36 Esters of fatty alkanoic acids.

[0051] That is, the fatty alkanoic acid can be a saturated or unsaturated fatty acid having an alkyl group containing from 1 to 36 carbon atoms, such as, in one aspect, from 1 to 22 carbon atoms. Suitable fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, oleic acid, and mixtures thereof.

[0052] In addition, suitable sugars or derivatives thereof, vitamins or derivatives thereof, glycerol or derivatives thereof include: sucrose, mannitol, sorbitol, erythritol, xylitol, lactitol, isomalt, maltitol, hydrogenated starch hydrolysate, arabitol, galactitol, glycerol, threitol, ribitol, fucitol, iditol, heptyl alcohol, their derivatives, and / or their combinations; water-soluble vitamins (such as ascorbic acid) or derivatives thereof; and monoglycerol, diglycerol and triglycerol, or their combinations. In one aspect, the derivatives may include any one or more of the above-mentioned substances, such as sorbitan derived from sorbitol. However, no matter which sugar or derivatives thereof, vitamin or derivatives thereof, glycerol or derivatives thereof are selected, in one aspect, the sugar or derivatives thereof, vitamin or derivatives thereof, glycerol or derivatives thereof are selected so that the ester has amphiphilicity.

[0053] However, as described above, in one aspect, the self-assembling gelation activator comprises an ester bond that bonds a sugar or a derivative thereof, a vitamin or a derivative thereof, a glycerol or a derivative thereof, or a combination thereof to a fatty acid. Thus, in one aspect, a sugar or a derivative thereof, a vitamin or a derivative thereof, a glycerol or a derivative thereof, or a combination thereof to a C 1 -C 36 Suitable esters of fatty alkanoic acids may include ascorbic acid alkanoate, sorbitan alkanoate, monoalkanoic acid triglyceride, sucrose alkanoate, or combinations thereof. For example, in one aspect, sugar or its derivatives, vitamin or its derivatives, glycerol or its derivatives, or combinations thereof are combined with C 1 -C 36 Suitable esters of fatty alkanoic acids can be ascorbyl palmitate, ascorbyl caprate, ascorbyl laurate, ascorbyl caprylate, ascorbyl myristate, ascorbyl oleate, sorbitan monostearate, sorbitan laurate, sorbitan caprylate, sorbitan myristate, sorbitan oleate, glycerol palmitate, glycerol monocaprate, glycerol monocaprylate, glycerol monostearate, glycerol monooleate, sucrose palmitate, sucrose monocaprate, sucrose monostearate, sucrose laurate, sucrose caprylate, sucrose myristate, sucrose oleate, or combinations thereof.

[0054] B. Ammonium salt

[0055] The organic acid used to form the ammonium salt may be a weak acid in the sense that the first acid dissociation constant (pK) of the organic acid measured at 25°C is a1) is typically from about 0 to about 11, in some embodiments from about 1 to about 10, and in some embodiments from about 2 to about 10. Any suitable weak organic acid can be used in the present invention, such as carboxylic acids, such as acrylic acid, methacrylic acid, malonic acid, succinic acid, salicylic acid, sulfosalicylic acid, adipic acid, maleic acid, malic acid, oleic acid, gallic acid, tartaric acid (e.g., dextrotartaric acid, mesotartaric acid, etc.), citric acid, formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, phthalic acid, isophthalic acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, itaconic acid, trifluoroacetic acid, barbituric acid, cinnamic acid, benzoic acid, 4-hydroxybenzoic acid, aminobenzoic acid, etc., mixtures thereof, etc. Polybasic acids (e.g., dibasic acids, tribasic acids, etc.) are particularly suitable for forming salts, such as adipic acid (pK a1 is 4.43 and pK a2 5.41), α-tartaric acid (pK a1 is 2.98 and pK a2 is 4.34), meso-tartaric acid (pK a1 is 3.22 and pK a2 is 4.82), oxalic acid (pK a1 is 1.23 and pK a2 is 4.19), lactic acid (pK a1 is 3.13, pK a2 is 4.76 and pK a3 6.40), etc. Although the actual amount may vary depending on the specific type of salt used, its solubility in the solvent system, and the presence of other ingredients, the content of ammonium salt in the electrolyte is generally about 1 wt.% to about 40 wt.%, in some embodiments, about 2 wt.% to about 30 wt.%, in some embodiments, about 3 wt.% to about 25 wt.%, and in some embodiments, about 4 wt.% to about 20 wt.%.

[0056] C. Acid

[0057] One or more acids may also be used to help achieve the desired pH and conductivity values. Suitable acids may include, for example, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid, etc.; organic acids, including carboxylic acids such as acrylic acid, methacrylic acid, malonic acid, succinic acid, salicylic acid, sulfosalicylic acid, adipic acid, maleic acid, malic acid, oleic acid, gallic acid, tartaric acid, citric acid, formic acid, acetic acid, ethylenediaminetetraacetic acid, etc. acid, "EDTA"), glycolic acid, oxalic acid, propionic acid, phthalic acid, isophthalic acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, itaconic acid, trifluoroacetic acid, barbituric acid, cinnamic acid, benzoic acid, 4-hydroxybenzoic acid, aminobenzoic acid, etc.; sulfonic acids, such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfonic acid, styrenesulfonic acid, naphthalene disulfonic acid, hydroxybenzenesulfonic acid, etc.; polymeric acids, such as poly (acrylic) acid or poly (methacrylic) acid and copolymers thereof (e.g., maleic acid-acrylic acid copolymer, sulfonic acid-acrylic acid copolymer, styrene-acrylic acid copolymer), carrageenan, carboxymethyl cellulose, alginic acid, etc. EDTA may be particularly suitable for use in the present invention because EDTA can not only reduce the pH of the electrolyte, but also act as a complexing agent for any metal impurities in the particles that may be present. In any case, as described above, it should be clear that the gelation process of the working electrolyte discussed herein does not require the use of strong acids, large amounts of acid and / or low pH to initiate gelation.

[0058] Although the total concentration of the acid can vary, the content of the acid in the electrolyte is generally about 0.01wt.% to about 5wt.%, about 0.05wt.% to about 4wt.% in some embodiments, and about 0.1wt.% to about 2wt.% in some embodiments. In a particular embodiment, a mixture of different acids, such as a mixture of an inorganic acid and an organic acid, can be used. In such an embodiment, the inorganic acid (e.g., phosphoric acid) can account for about 0.005wt.% to about 5wt.% of the electrolyte, about 0.01wt.% to about 3wt.% in some embodiments, and about 0.05wt.% to about 1wt.% in some embodiments, and similarly, the organic acid (e.g., EDTA) can account for about 0.005wt.% to about 5wt.% of the electrolyte, about 0.01wt.% to about 3wt.% in some embodiments, and about 0.05wt.% to about 1wt.% in some embodiments.

[0059] D. Aqueous solvent system

[0060] The electrolyte is aqueous because it contains an aqueous solvent, such as water (e.g., deionized water). For example, water (e.g., deionized water) can account for about 20 wt% to about 95 wt% of the electrolyte, in some embodiments about 30 wt% to about 90 wt%, and in some embodiments about 40 wt% to about 85 wt%. A co-solvent can also be used to form a solvent mixture. Suitable co-solvents may include, for example, glycols (e.g., ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycol, ethoxydiglycol, dipropylene glycol, etc.); glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, isopropyl glycol ether, etc.); alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, and butanol); ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone); esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, methoxypropyl acetate, ethylene carbonate, propylene carbonate, etc.); amides (e.g., dimethylformamide, dimethylacetamide, dimethyloctanoic acid / capric acid fatty acid amide, and N-alkylpyrrolidone); sulfoxides or sulfones (e.g., dimethyl sulfoxide (DMSO) and sulfolane), and the like. Such mixtures typically contain water in an amount of about 60 wt.% to about 95 wt.%, in some embodiments about 65 wt.% to about 90 wt.%, and in some embodiments about 70 wt.% to about 87.5 wt.%, of the solvent system, and the co-solvent content is about 5 wt.% to about 40 wt.%, in some embodiments about 10 wt.% to about 35 wt.%, and in some embodiments about 12.5 wt.% to about 30 wt.%. Similarly, when such mixtures are used, water typically accounts for about 30 wt.% to about 80 wt.%, in some embodiments about 35 wt.% to about 75 wt.%, and in some embodiments about 45 wt.% to about 65 wt.%, of the electrolyte, and the co-solvent may account for about 5 wt.% to about 40 wt.%, in some embodiments about 10 wt.% to about 35 wt.%, and in some embodiments about 12.5 wt.% to about 30 wt.%.

[0061] That is, as described above, the present disclosure has found that by using a small amount of gelling activator, a smaller amount of co-solvent can be used without affecting the gelling effect of the gelling activator and the inorganic oxide particles. Surprisingly, a smaller amount of co-solvent can also contribute to the excellent conductivity of the working electrolyte, which will be discussed in more detail below.

[0062] E. Inorganic oxide particles

[0063] As described above, inorganic oxide particles are also used in the electrolyte to form a gel having a certain desired viscosity. The amount of particles in the electrolyte can depend on the desired degree of gelation and the specific properties and concentrations of the other components in the electrolyte. However, the inorganic oxide particles generally account for about 0.5 wt.% to about 15 wt.% of the electrolyte, in some embodiments, about 1 wt.% to about 10 wt.%, and in some embodiments, about 2.5 wt.% to about 5 wt.%.

[0064] Depending on the desired result, the particles can have various forms, shapes and sizes. For example, the shape of the particles can be spherical, crystalline, rod-shaped, disc-shaped, tubular, linear, etc. The average size of the particles can be less than about 1000 nanometers, in some embodiments, from about 1 nanometer to about 500 nanometers, in some embodiments, from about 2 nanometers to about 200 nanometers, and in some embodiments, from about 4 nanometers to about 50 nanometers. As used herein, the average size of a particle refers to its average length, width, height and / or diameter. The particles also typically have a high specific surface area, such as about 50 square meters per gram (50 m 2 / g) to about 1000m 2 / g, in some embodiments about 100m 2 / g to about 600m 2 / g, and in some embodiments about 150m 2 / g to about 400m 2 / g. The term "specific surface area" generally refers to the surface area measured by the physical gas adsorption (BET) method described by Bruanauer, Emmet and Teller in the Journal of the American Chemical Society, Vol. 60, 1938, p. 309, using nitrogen as the adsorbed gas. This test can be performed using a QUANTACHROME Corporation, Syosset, New York. The particles can be prepared by measuring the amount of nitrogen adsorbed on the solid surface by a surface area analyzer that detects changes in the thermal conductivity of a flowing mixture of the adsorbent and an inert carrier gas (e.g., helium). In addition, the particles can also be relatively nonporous or solid. That is, the pore volume of the particles can be less than about 0.5 milliliters per gram (0.5 ml / g), in some embodiments less than about 0.4 milliliters per gram, in some embodiments less than about 0.3 ml / g, and in some embodiments from about 0.2 ml / g to about 0.3 ml / g. Without being limited by theory, it is believed that particles with such small size, high surface area, and solid properties can increase the gelation rate and enhance the uniformity and stability of the resulting suspension.

[0065] Inorganic oxide particles can be formed from a variety of materials, including but not limited to silicon dioxide, aluminum oxide, zirconium oxide, magnesium oxide, titanium dioxide, iron oxide, zinc oxide, copper oxide, etc., and combinations thereof. Particles can also be formed using a fumed process, a precipitation process, etc. However, since the fumed deposited particles have a larger specific surface area and a smaller particle size, they are particularly suitable for use in the present invention. For example, fumed silica is an amorphous SiO 2 , which can be prepared by gas phase hydrolysis of silicon tetrachloride in a hydrogen and oxygen flame. Three-dimensional branched chain aggregates are formed by fusion of primary particles in the flame. During cooling, these aggregates agglomerate into a fine powder having a particle size within the above range. Commercially suitable fumed silica particles may include, for example, those available from Cabot Corporation under the name of of particles.

[0066] For example, fumed silica has silanol groups, which can react under the initiation of a gelation activator to form a cross-linked network between each inorganic oxide particle, and the silanol groups can be cross-linked and / or self-assembled with the gelation initiator. In one example, a gel is formed by forming siloxane crosslinks (such as when an organometallic gelation activator is used) or by forming siloxane crosslinks and a self-assembled phase (such as when an acrylate is used), which traps the liquid phase of the electrolyte.

[0067] F. Other additives

[0068] The working electrolyte may also contain other ingredients that help improve the electrical properties of the capacitor. For example, a depolarizer may be used in the electrolyte to help inhibit the release of hydrogen at the cathode of the electrolytic capacitor, which may otherwise cause the capacitor to bulge and ultimately fail. When a depolarizer is used, the depolarizer typically comprises about 0.01 wt.% to about 5 wt.%, in some embodiments about 0.05 wt.% to about 2 wt.%, and in some embodiments about 0.1 wt.% to about 1 wt.% of the electrolyte. Suitable depolarizers may include nitroaromatic compounds such as 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 2-nitroacetophenone, 3-nitroacetophenone, 4-nitroacetophenone, 2-nitroanisole, 3-nitroanisole, 4-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, 2-nitrobenzyl alcohol, 3-nitrobenzyl alcohol, 4-nitrobenzyl alcohol, 2-nitrophthalic acid, 3-nitrophthalic acid, 4-nitrophthalic acid, etc. Nitroaromatic depolarizers particularly suitable for use in the present invention are nitrobenzoic acid and its anhydride or salt substituted with one or more alkyl groups (e.g., methyl, ethyl, propyl, butyl, etc.). Specific examples of such alkyl-substituted nitrobenzoic acid compounds include, for example, 2-methyl-3-nitrobenzoic acid; 2-methyl-6-nitrobenzoic acid; 3-methyl-2-nitrobenzoic acid; 3-methyl-4-nitrobenzoic acid; 3-methyl-6-nitrobenzoic acid; 4-methyl-3-nitrobenzoic acid; anhydrides or salts thereof, and the like.

[0069] The components of the electrolyte can be combined in a variety of ways before and / or after they are added to the capacitor. In a particular embodiment, the electrolyte can be gelled, or at least the gelling process can be initiated, by combining a gelling activator with the ammonium salt of an organic acid, the inorganic oxide particles, the acid and the solvent system before the electrolyte is contacted with the anode and / or cathode.

[0070] Once gelled, the electrolyte can be added to the capacitor in a variety of different ways. For example, in one embodiment, after the anode and cathode are placed in the desired configuration, the electrolyte only needs to be added to the capacitor. For example, this can be achieved by using a charging port. The anode can also be pre-impregnated with the gelled electrolyte, such as by dip coating, vacuum assisted impregnation or other techniques to improve the impregnation of the anode in the electrolyte before placement in the capacitor. Impregnation of the anode with the gelled electrolyte can further improve the degree of contact between the anode and the electrolyte. In either case, the inventors were surprised to find that the electrolyte can have a low initial viscosity and fluidity, so that the electrolyte can be accurately added to the capacitor. For example, the initial viscosity of the gel (e.g., 1 hour or less after gelation initiation, or any time period above with respect to gelation time, in one example, such as about 6 hours or more) can be in the range of about 1 centipoise to about 40 centipoise, in some embodiments, in the range of about 2 centipoise to about 30 centipoise, and in some embodiments, in the range of about 3 centipoise to about 10 centipoise when measured at 25°C using a Brookfield LVT viscometer (spindle No. 3, 60 rpm). Similarly, the initial phase angle δ of the gel is about 50° to 90°, in some embodiments, about 60° to 90°, and in some embodiments, about 80° to 90°, and the initial storage modulus G' of the gel is about 1 kPa or less, in some embodiments, about 0.1 kPa or less, and in some embodiments, 0 kPa to about 0.01 kPa.

[0071] However, after the electrolyte is added to the capacitor, the electrolyte can continue to gel until the viscosity increases, such as reaching a viscosity, phase angle δ and / or storage modulus G' within the above-mentioned target range. The "semi-solid" or "solid" transition can occur after a relatively long period of time after causing gelation, such as about 2 hours to about 24 hours, in some embodiments about 4 hours to about 18 hours, and in some embodiments about 6 hours to about 12 hours, or any range or value discussed above. The transition can also occur before and / or after the anode is added to the capacitor and contacted with the cathode. If necessary (for example, if the anode is impregnated before adding the capacitor element), additional "filling" electrolyte can be added to ensure good electrical contact between the impregnated anode and cathode. The filling electrolyte can be formed according to the present invention, or can be formed by other known components.

[0072] two, cathode

[0073] The cathode comprises at least one substrate. On the one hand, the substrate can be coated with a conductive polymer. The substrate can include metals such as tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), their alloys (e.g., conductive oxides), their composite materials (e.g., metals coated with conductive oxides), etc. Titanium and tantalum and their alloys are particularly suitable for use in the present invention. As is well known to those skilled in the art, the geometric configuration of the substrate can generally vary, such as in the form of containers, cans, foils, sheets, screens, nets, etc. For example, in one embodiment, the metal substrate is formed into a shell having a generally cylindrical shape. However, it should be understood that any geometric configuration can be used in the present invention, such as D-shaped, rectangular, triangular, prism-shaped, etc. Optionally, the shell can selectively include a cover covering the anode and the electrolyte, and the cover can be formed of the same or different material as the shell.

[0074] The substrate may be roughened to increase its surface area and to increase the extent to which the conductive polymer can adhere to it. For example, in one embodiment, the surface is chemically etched, such as by applying a solution of a corrosive substance (e.g., hydrochloric acid) to the surface. The surface may also be electrochemically etched, such as by applying a voltage to a solution of a corrosive substance to cause it to electrolyze. The voltage may be raised to a level high enough to induce "sparking" at the surface of the substrate, which is believed to produce a localized surface temperature high enough to etch the substrate. This technique is commonly used in Germany Dreissig et al. In the U.S. patent application with publication number 2010 / 0142124, a more detailed description is provided. In addition to chemical or electrochemical roughening techniques, mechanical roughening can also be used. For example, in one embodiment, the surface of the metal substrate can be subjected to abrasive blasting by pushing a stream of abrasive media (e.g., sand) to at least a portion of the surface of the substrate.

[0075] The conductive polymer coating may be formed of one or more layers. The materials used for such coatings may vary. The total thickness of the solid electrolyte is typically from about 1 μm to about 50 μm, and in some embodiments from about 5 μm to about 20 μm. For example, in one embodiment, the material includes a conductive polymer, which may be an intrinsic conductive polymer having a repeating unit of the following formula (I):

[0076]

[0077] in,

[0078] R is (CH 2 ) a -O-(CH 2 )b -L, where L is a bond or HC([CH 2 ] c H);

[0079] a is 0 to 10, in some embodiments 0 to 6, and in some embodiments 1 to 4 (e.g., 1);

[0080] b is 1 to 18, in some embodiments 1 to 10, and in some embodiments 2 to 6 (e.g., 2, 3, 4, or 5);

[0081] c is 0 to 10, in some embodiments 0 to 6, and in some embodiments 1 to 4 (e.g., 1);

[0082] Z is an anion, such as SO 3 - 、C(O)O - , BF 4 - CF 3 SO 3 - , SbF 6 - 、N(SO 2 CF 3 ) 2 - , C 4 H 3 O 4 - , ClO 4 - wait;

[0083] X is a cation such as a hydrogen ion, an alkali metal ion (eg, a lithium ion, a sodium ion, a bismuth ion, a cesium ion, or a potassium ion), an ammonium ion, or the like.

[0084] In a particular embodiment, Z in formula (I) is a sulfonate ion, such that the intrinsically conductive polymer comprises repeating units of the following formula (II):

[0085]

[0086] wherein R and X are as defined above. In formula (I) or (II), a is preferably 1, and b is preferably 3 or 4. Likewise, X is preferably sodium or potassium.

[0087] If necessary, the polymer can be a copolymer comprising other types of repeating units. In this embodiment, the repeating unit of formula (I) generally accounts for about 50mol.% or more of the total content of the repeating unit of formula (I) and / or (II) in the copolymer, in some embodiments about 75mol.% to about 99mol.%, and in some embodiments about 85mol.% to about 95mol.%. Of course, the polymer can also be a homopolymer comprising 100mol.% of the repeating unit of formula (I) and / or formula (II).

[0088] In another embodiment, the intrinsically conductive polymer has repeating thiophene units of the following general formula (III):

[0089]

[0090] in,

[0091] a and b are as defined above;

[0092] R 5 is an optionally substituted C 1 -C 6 a straight-chain or branched alkyl group (e.g., a methyl group), or a halogen atom (e.g., a fluorine atom);

[0093] X is a hydrogen atom, an alkali metal (such as Li, Na or K), NH(R 1 ) 3 or HNC 5 H 5 , where R 1 are each independently a hydrogen atom or an optionally substituted C 1 -C 6 alkyl.

[0094] Specific examples of such homopolymers include poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulfonic acid, salt) and poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulfonic acid, salt). Specific examples of thiophene compounds used to form such repeating units are described in U.S. Pat. No. 9,718,905 and may include, for example, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate -yl)methoxy]-1-isopropyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-fluoro-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy] ][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, potassium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, ammonium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, triethylammonium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, and the like, and combinations thereof. Each of the above-exemplified thiophene monomers can be prepared from thieno[3,4-b]-1,4-dioxin-2-methanol and a branched sultone compound according to a known method (eg, Journal of Electroanalytical Chemistry, Vol. 443, pp. 217-226 (1998)).

[0095] Intrinsically conductive polymers can be formed by various techniques well known to those skilled in the art. For example, in one particular embodiment, 3,4-ethylenedioxythiophene salts can be polymerized in the presence of an oxidation catalyst. Derivatives of these monomers can also be used, for example, dimers or trimers of the above compounds. The derivatives can be composed of the same or different monomer units and can be used in pure form or mixed with each other and / or with the monomers. Oxidized or reduced forms of these precursors can also be used. The oxidation catalyst can be a transition metal salt, such as a salt of an inorganic or organic acid containing the following: ammonium, sodium, gold, iron (III), copper (II), chromium (VI), cerium (IV), manganese (IV), manganese (VII) or ruthenium (III) cations. Particularly suitable transition metal salts include: halides (e.g., FeCl 3 or HAuCl 4 ); other inorganic acid salts (such as Fe(ClO 4 ) 3 , Fe 2 (SO 4 ) 3 NH 4 ) 2 S 2 O 8 Or Na 3 Mo 12 PO 4 0); and salts of organic acids and inorganic acids including organic groups. Examples of salts of inorganic acids having organic groups include, for example, C 1 To C 20 Iron (III) salts of sulfuric acid monoesters of alkanols (e.g., iron (III) salts of lauryl sulfate). Similarly, examples of salts of organic acids include, for example, C 1 To C 20 An iron (III) salt of an alkanesulfonic acid (e.g., methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid or dodecanesulfonic acid); an iron (III) salt of an aliphatic perfluorosulfonic acid (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid or perfluorooctanesulfonic acid); C 1 To C 20 an iron(III) salt of an aliphatic carboxylic acid (e.g., 2-ethylhexyl carboxylic acid); an iron(III) salt of an aliphatic perfluorocarboxylic acid (e.g., trifluoroacetic acid or perfluorooctanoic acid); 1 To C 20 Iron (III) salts of alkyl-substituted aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid); iron (III) salts of cycloalkanesulfonic acids (e.g., camphorsulfonic acid), etc. Mixtures of the above-mentioned salts can also be used.

[0096] Oxidative polymerization usually occurs in the presence of one or more solvents. Suitable solvents may include, for example, water, glycols (e.g., ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycol, ethoxydiglycol, dipropylene glycol, etc.); glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, isopropyl glycol ether, etc.); alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, and butanol); ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone); esters (e.g., ethyl acetate, butyl acetate, diethylene glycol ether acetate, methoxypropyl acetate, ethylene carbonate, propylene carbonate, etc.); amides (e.g., dimethylformamide, dimethylacetamide, dimethyl caprylic acid / capric acid fatty acid amide, and N-alkylpyrrolidone); sulfoxides or sulfones (e.g., dimethyl sulfoxide (DMSO) and cyclopentane); phenolic compounds (e.g., toluene, xylene, etc.), etc. Water is a particularly suitable solvent for the reaction. The temperature at which the reaction takes place typically varies between about -20°C and about 140°C, and in some embodiments between about 20°C and about 100°C. After the reaction is complete, any salt impurities may be removed using known filtration techniques.

[0097] Regardless of how the polymer is formed, the polymer is considered to be "intrinsically" conductive, having a positive charge located on the backbone, and the positive charge is at least partially compensated by anions covalently bonded to the polymer. For example, the polymer can have a relatively high specific conductivity in a dry state, about 1 Siemens / cm (S / cm) or more, about 10 S / cm or more in some embodiments, about 20 S / cm or more in some embodiments, and about 50 S / cm to about 500 S / cm in some embodiments. Due to its intrinsic conductivity, the solid electrolyte does not require the addition of traditional dopants such as polystyrene sulfonic acid. In fact, the solid electrolyte can be substantially free of such dopants. However, it should be understood that in certain embodiments of the present invention, dopants can be used. However, when used, the content of the dopant present in the solid electrolyte is generally about 5 wt.% or less, about 2 wt.% or less in some embodiments, and about 1 wt.% or less in some embodiments.

[0098] The polymer is also typically highly soluble in water, which enables the polymer to be more easily and efficiently applied to the anode. The soluble polymer can also more easily impregnate the small pores formed by the high specific charge powder, so that the resulting solid electrolyte has a "film-like" configuration and covers at least a portion of the anode in a substantially uniform manner. This improves the quality of the oxide formed and its surface coverage, thereby enhancing the electrical performance of the capacitor assembly.

[0099] i. Inner Layer

[0100] Solid electrolytes are generally formed by one or more "inner" conductive polymer layers. In this context, the term "inner" refers to one or more layers formed by the same material, directly or through another layer (e.g., an adhesive layer) covering the substrate. For example, the inner layer generally comprises an intrinsic conductive polymer as described above. By using this polymer, the inventors found that the capacitor element can exhibit better performance at high voltages. In a particular embodiment, the inner layer is generally free of non-intrinsically conductive polymers (extrinsically conductive polymers), and is therefore mainly formed by intrinsic conductive polymers. More specifically, the intrinsic conductive polymer can account for about 50wt.% or more of the inner layer, about 70wt.% or more in some embodiments, and about 90wt.% or more (e.g., 100wt.%) in some embodiments. One or more inner layers can be used. For example, the solid electrolyte generally comprises 2 to 30 inner layers, 4 to 20 inner layers in some embodiments, and about 5 to 15 inner layers (e.g., 10 layers) in some embodiments. However, it should be understood that, on the one hand, the inner layer can include non-intrinsically conductive polymers, or, on the one hand, it is generally free of intrinsic conductive polymers.

[0101] However, when the inner layer includes an intrinsic conductive polymer, the inner layer can be coated in the form of a solution. The concentration of the polymer can vary according to the desired viscosity and the specific manner in which the layer is applied to the anode. However, the polymer generally accounts for about 0.1wt% to about 10wt% of the solution, about 0.4wt% to about 5wt% in some embodiments, and about 0.5wt% to about 4wt% in some embodiments. Similarly, the solvent can account for about 90wt% to about 99.9wt% of the solution, about 95wt% to about 99.6wt% in some embodiments, and about 96wt% to about 99.5wt% in some embodiments. Although other solvents can certainly be used, it is generally desired that water is the main solvent so that the solution is considered to be an "aqueous" solution. In most embodiments, for example, water accounts for at least 50wt.% of the solvent used, at least about 75wt.% in some embodiments, and about 90wt.% to 100wt.% in some embodiments. When a solution is used, the solution can be applied to the anode using any known technique, such as dipping, casting (e.g., curtain coating, spin coating, etc.), printing (e.g., gravure printing, offset printing, screen printing, etc.), etc. The resulting conductive polymer layer can be dried and / or washed after being applied to the anode.

[0102] ii. Outer Layer

[0103] The solid electrolyte may comprise only an "inner layer" and / or an "outer layer", so that the solid electrolyte is substantially formed of the same material. However, in other embodiments, the solid electrolyte may also comprise one or more "outer" conductive polymer layers, which are formed of a material different from the inner layer and are covered on the inner layer and / or on the substrate (if the inner layer is not present). For example, the outer layer may be formed by a dispersion of non-intrinsic conductive polymer particles. In a particular embodiment, the outer layer is mainly formed by such non-intrinsic conductive polymer particles, because they account for about 50 wt.% or more of the corresponding outer layer, about 70 wt.% or more in some embodiments, and about 90 wt.% or more (e.g., 100 wt.%) in some embodiments. One or more outer layers may be used. For example, the solid electrolyte may comprise 2 to 30 outer layers, 4 to 20 outer layers in some embodiments, and about 5 to 15 outer layers in some embodiments, optionally, each of the outer layers is formed by a dispersion of non-intrinsic electrical polymer particles.

[0104] When a non-intrinsic conductive polymer is used, the non-intrinsic conductive polymer may, for example, have a repeating unit of the following formula (IV):

[0105]

[0106] in,

[0107] R 7 Is a straight or branched chain C 1 To C 18 Alkyl groups (e.g., methyl, ethyl, n-propyl or isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, etc.); C 5 To C 12 Cycloalkyl groups (e.g., cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc.); C 6 To C 14 Aryl group (eg, phenyl, naphthyl, etc.); C 7 To C 18 Aralkyl groups (e.g., benzyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5-xylyl, 2,6-xylyl, 3,4-xylyl, 3,5-xylyl, mesityl, etc.); C 1 To C 4 a hydroxyalkyl group or a hydroxy group; and

[0108] q is an integer from 0 to 8, in some embodiments from 0 to 2, and in one embodiment is 0. In a specific embodiment, "q" is 0 and the polymer is poly(3,4-ethylenedioxythiophene). A commercially suitable example of a monomer suitable for forming such a polymer is 3,4-ethylenedioxthiophene, which is commercially available from Heraeus under the name Clevios TM M.

[0109] The polymers of formula (III) are generally considered to be "non-intrinsic" conductive, requiring the presence of a separate counterion that is not covalently bonded to the polymer. The counterion can be a monomer or polymer anion that counteracts the charge of the conductive polymer. For example, the polymer anion can be an anion of a polymeric carboxylic acid (e.g., polyacrylic acid, polymethacrylic acid, polymaleic acid, etc.) and a polymeric sulfonic acid (e.g., polystyrene sulfonic acid (PSS), polyvinyl sulfonic acid, etc.). The acid can also be a copolymer, such as a copolymer of ethylene carboxylic acid and ethylene sulfonic acid with other polymerizable monomers (such as acrylates and styrene, etc.). Similarly, suitable monomer anions include, for example, C 1 To C 20 anions of alkylsulfonic acids (e.g., dodecylsulfonic acid); anions of aliphatic perfluorosulfonic acids (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, or perfluorooctanesulfonic acid); C 1 To C 20 anion of an aliphatic carboxylic acid (e.g., 2-ethylhexyl carboxylic acid); anion of an aliphatic perfluoroformic acid (e.g., trifluoroacetic acid or perfluorooctanoic acid); optionally C 1 To C 20 Anions of alkyl-substituted aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid); anions of cycloalkylsulfonic acids (e.g., camphorsulfonic acid or tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexafluoroarsenate, or hexachloroantimonate); and the like. Particularly suitable counter anions are polymeric anions, such as anions of polymeric carboxylic acids or polymeric sulfonic acids (e.g., polystyrenesulfonic acid (PSS)). The molecular weight of such polymeric anions is typically in the range of about 1,000 to about 2,000,000, and in some embodiments in the range of about 2,000 to about 500,000.

[0110] The average size (e.g., diameter) of the extrinsic conductive particles is typically from about 1 nanometer to about 150 nanometers, from about 2 nanometers to about 50 nanometers in some embodiments, and from about 5 nanometers to about 40 nanometers in some embodiments. The diameter of the particles can be determined using known techniques (such as by ultracentrifugation, laser diffraction, etc.). The shape of the particles can also vary. For example, in one particular embodiment, the particles are spherical. However, it should be understood that the present invention also contemplates other shapes, such as plate-shaped, rod-shaped, disk-shaped, bar-shaped, tube-shaped, irregular shapes, etc. The concentration of the particles in the dispersion can vary depending on the desired viscosity of the dispersion and the particular manner in which the dispersion is coated onto the capacitor element. However, the particles generally make up from about 0.1 wt.% to about 10 wt.% of the dispersion, from about 0.4 wt.% to about 5 wt.% in some embodiments, and from about 0.5 wt.% to about 4 wt.% in some embodiments.

[0111] The dispersion can also include one or more binders to further enhance the adhesion of the polymeric layer and also improve the stability of the particles within the dispersion. The binder can be organic in nature, such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyacrylate, polyacrylamide, polymethacrylate, polymethacrylamide, polyacrylonitrile, styrene / acrylic ester, vinyl acetate / acrylic ester, and ethylene / vinyl acetate copolymer, polybutadiene, polyisoprene, polystyrene, polyether, polyester, polycarbonate, polyurethane, polyamide, polyimide, polysulfone, melamine formaldehyde resin, epoxy resin, silicone resin, or cellulose. Crosslinking agents can also be used to enhance the adhesion ability of the binder. Such crosslinking agents can include, for example, melamine compounds, masked isocyanates, or functional silanes such as 3-glycidoxypropyltrimethoxysilane, tetraethoxysilane, and the hydrolysis product of tetraethoxysilane; or crosslinkable polymers such as polyurethane, polyacrylate, or polyolefin, and a subsequent crosslinking reaction occurs.

[0112] Dispersants can also be used to improve the ability to coat the layer onto the anode. Suitable dispersants include solvents such as aliphatic alcohols (e.g., methanol, ethanol, isopropanol, and butanol), aliphatic ketones (e.g., acetone and methyl ethyl ketone), aliphatic carboxylic acid esters (e.g., ethyl acetate and butyl acetate), aromatic hydrocarbons (e.g., toluene and xylene), aliphatic hydrocarbons (e.g., hexane, heptane, and cyclohexane), chlorinated hydrocarbons (e.g., dichloromethane and dichloroethane), aliphatic nitriles (e.g., acetonitrile), aliphatic sulfoxides and aliphatic sulfones (e.g., dimethyl sulfoxide and sulfolane), aliphatic carboxylic acid amides (e.g., N-methylacetamide, dimethylacetamide, and dimethylformamide), aliphatic ethers and araliphatic ethers (e.g., diethyl ether and anisole), water, and mixtures of any of the above solvents. A particularly suitable dispersant is water.

[0113] In addition to those ingredients mentioned above, other ingredients may also be used in the dispersion. For example, conventional fillers may be used, the size of which is from about 10 nanometers to about 100 microns, in some embodiments from about 50 nanometers to about 50 microns, and in some embodiments from about 100 nanometers to about 30 microns. Examples of such fillers include calcium carbonate, silicates, silicon dioxide, calcium sulfate or barium sulfate, aluminum hydroxide, glass fibers or beads, wood flour, cellulose powder, carbon black, conductive polymers, and the like. The filler may be introduced into the dispersion in powder form, but may also be present in another form, such as fibers.

[0114] Surface active substances such as ionic surfactants or nonionic surfactants can also be used in the dispersion. In addition, adhesives such as organofunctional silanes or their hydrolyzates, for example, 3-glycidyloxypropyltrialkoxysilane, 3-aminopropyl-triethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane can also be used. The dispersion may also contain additives that improve conductivity, such as ether-containing compounds (e.g., tetrahydrofuran), lactone-containing compounds (e.g., γ-butyrolactone or γ-valerolactone), amide- or lactam-containing compounds (e.g., caprolactam, N-methylcaprolactam, N,N-dimethylacetamide, N-methylacetamide, N,N-dimethylformamide (DMF), N-methylformamide, N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone or pyrrolidone), sulfones and sulfoxides (e.g., sulfolane (tetrahydrothiophene sulfone) or dimethyl sulfoxide (DMSO)), sugars or sugar derivatives (e.g., sucrose, glucose, fructose or lactose), sugar alcohols (e.g., sorbitol or mannitol), furan derivatives (e.g., 2-furancarboxylic acid or 3-furanic acid), and alcohols (e.g., ethylene glycol, glycerol, diethylene glycol or triethylene glycol).

[0115] The dispersion can be applied using various known techniques, such as by spin coating, injection, pouring, dripping, injecting, spraying, doctor blading, brushing, printing (e.g., inkjet printing, screen printing, or pad printing), or dipping. The viscosity of the dispersion is typically from about 0.1 mPas to about 100,000 mPas (measured at a shear rate of 100 s-1), in some embodiments from about 1 mPas to about 10,000 mPas, in some embodiments from about 10 mPas to about 1500 mPas, and in some embodiments from about 100 mPas to about 1000 mPas.

[0116] However, as described above, like intrinsic conductive polymers, thiophene monomers of non-intrinsic conductive polymers can be chemically polymerized in the presence of an oxidation catalyst. The oxidation catalyst generally includes transition metal cations, such as iron (III), copper (II), chromium (VI), cerium (IV), manganese (IV), manganese (VII), ruthenium (III) cations, etc. Dopants can also be used to provide excess charge to the conductive polymer and stabilize the conductivity of the polymer. Dopants generally include inorganic anions or organic anions, such as ions of sulfonic acid. In certain embodiments, the oxidation catalyst used in the precursor solution has both catalytic function and doping function, because the oxidation catalyst includes cations (e.g., transition metal ions) and anions (e.g., sulfonic acid). For example, the oxidation catalyst can be a transition metal salt including iron (III) cations, such as iron (III) halides (e.g., FeCl 3 ) or other iron(III) salts of inorganic acids (such as Fe(ClO 4 ) 3 or Fe 2 (SO 4 ) 3 ) and iron (III) salts of organic acids and inorganic acids including organic groups. Examples of iron (III) salts of inorganic acids having organic groups include, for example, C 1 To C 20 Iron (III) salts of sulfuric acid monoesters of alkanols (e.g., iron (III) salts of lauryl sulfate). Similarly, examples of iron (III) salts of organic acids include, for example, C 1 To C 20 An iron (III) salt of an alkanesulfonic acid (e.g., methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid or dodecanesulfonic acid); an iron (III) salt of an aliphatic perfluorosulfonic acid (e.g., trifluoromethanesulfonic acid, perfluorobutanesulfonic acid or perfluorooctanesulfonic acid); C 1 To C 20 an iron(III) salt of an aliphatic carboxylic acid (e.g., 2-ethylhexanoic acid); an iron(III) salt of an aliphatic perfluorocarboxylic acid (e.g., trifluoroacetic acid or perfluorooctanoic acid); optionally 1 To C 20 Iron (III) salts of alkyl-substituted aromatic sulfonic acids (e.g., benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid); Iron (III) salts of cycloalkanesulfonic acids (e.g., camphorsulfonic acid), etc. Mixtures of the above-mentioned iron (III) salts may also be used. Iron (III)-p-toluenesulfonate, iron (III)-o-toluenesulfonate and mixtures thereof are particularly suitable. A commercially suitable example of iron (III)-p-toluenesulfonate is available from Heraeus Clevios under the name Clevios TM C.

[0117] On the other hand, the oxidation catalyst and the monomer can be applied sequentially or together so that the polymerization reaction occurs in situ on the substrate. Suitable coating techniques can include screen printing, dipping, electrophoretic coating and spraying, and can be used to form a conductive polymer coating. As an example, the monomer can first be mixed with the oxidation catalyst to form a precursor solution. Once the mixture is formed, the mixture can be applied to the substrate and then polymerized to form a conductive coating on the surface. Alternatively, the oxidation catalyst and the monomer can be applied sequentially. For example, in one embodiment, the oxidation catalyst is dissolved in an organic solvent (e.g., butanol) and then applied as an impregnation solution. The substrate can then be dried to remove the solvent from the substrate. Thereafter, the substrate can be immersed in a solution containing the monomer. Polymerization is typically carried out at a temperature of about -10°C to about 250°C, and in some embodiments at a temperature of about 0°C to about 200°C, depending on the oxidant used and the desired reaction time. Suitable polymerization techniques such as those described above can be used in Biler Still other methods for applying such conductive coatings can be described in more detail in U.S. Pat. Sakata No. 5,457,862, Sakata et al., U.S. Pat. No. 5,473,503, Sakata et al., U.S. Pat. No. 5,729,428 and Kudoh et al., U.S. Pat. No. 5,812,367.

[0118] If necessary, one or more of the above-mentioned coating steps can be repeated until the desired coating thickness is reached. In some embodiments, only a relatively thin coating is formed at one time. The total target thickness of the coating can usually vary according to the desired performance of the capacitor. Typically, the thickness of the conductive polymer coating formed is from about 0.2 microns (μm) to about 50 μm, from about 0.5 μm to about 20 μm in some embodiments, and from about 1 μm to about 5 μm in some embodiments. It should be understood that the thickness of the coating is not necessarily the same at all locations on the substrate. However, the average thickness of the coating on the substrate usually falls within the above range.

[0119] Optionally, the conductive polymer layer can be optionally healed. The repair can be performed after each application of the conductive polymer layer, or can be performed after the entire coating is applied. In some embodiments, the conductive polymer can be repaired by immersing the component in an electrolyte solution and then applying a constant voltage to the solution until the current drops to a pre-selected level. If necessary, this repair can be completed in multiple steps. For example, the electrolyte solution can be a dilute solution of monomers, catalysts, and dopants in an alcoholic solvent (e.g., ethanol). If necessary, the coating can also be cleaned to remove various by-products and excess reagents, etc.

[0120] three. anode

[0121] The anode is typically formed from a valve metal composition. The specific charge of the composition may vary, such as from about 2000 μF*V / g to about 80,000 μF*V / g, in some embodiments from about 5,000 μF*V / g to about 40,000 μF*V / g or more, and in some embodiments from about 10,000 μF*V / g to about 20,000 μF*V / g. The valve metal composition comprises a valve metal (i.e., a metal capable of oxidation) or a compound of a valve metal, such as tantalum, niobium, aluminum, hafnium, titanium, their alloys, their oxides, and their nitrides. For example, the valve metal composition may comprise a conductive oxide of niobium, such as niobium oxide having an atomic ratio of niobium to oxygen of 1:1.0±1.0, in some embodiments 1:1.0±0.3, in some embodiments 1:1.0±0.1, and in some embodiments 1:1.0±0.05. Niobium oxide may be NbO 0.7 、NbO 1.0 、NbO 1.1 and NbO 2 Examples of such valve metal oxides are Fife U.S. Patent No. 6,322,912, Fife et al., U.S. Pat. No. 6,391,275, Fife et al., U.S. Pat. No. 6,416,730, Fife U.S. Patent No. 6,527,937, Kimmel et al., U.S. Pat. No. 6,576,099, Fife et al., U.S. Pat. No. 6,592,740, Kimmel et al., U.S. Pat. No. 6,639,787 and Kimmel et al., described in U.S. Pat. No. 7,220,397, and also in Schnitter U.S. Patent Application Publication No. 2005 / 0019581, Schnitter et al., U.S. Patent Application Publication No. 2005 / 0103638, Thomas et al., is described in U.S. Patent Application Publication No. 2005 / 0013765.

[0122] To form the anode, a powder of a valve metal composition is typically used. The powder may include particles of various shapes, such as nodular, angular, flake, etc., and mixtures thereof. Particularly suitable powders are tantalum powders available from Cabot Corp. (e.g., C255 flake powder, TU4D flake / spherical powder, etc.) and tantalum powders available from HC Starck (e.g., NH175 spherical powder). The valve metal composition may be formed using techniques known to those skilled in the art. For example, the precursor tantalum powder may be reduced to a tantalum salt (e.g., potassium fluorotantalate (K 2 Tf 7 ), sodium fluorotantalate (Na 2 Tf 7 ), tantalum pentachloride (TaCl 5 ) and the like). The precursor powder may initially contain particles in a granular form, and then known techniques may be used to deform the precursor powder or flatten the precursor powder into a sheet-like form. The technique of reducing the thickness of the particles includes mechanically grinding the powder to grind the particles into a smaller size. In the present invention, any of the various grinding techniques may be used to achieve the desired particle properties. For example, the powder may be dispersed in a fluid medium (e.g., ethanol, methanol, fluorinated liquid, etc.) to form a slurry. The slurry may then be mixed with a grinding medium (e.g., a metal ball, such as a tantalum ball) in a mill. The number of grinding media may generally vary depending on the size of the mill, such as from about 100 to about 2000, and in some embodiments from about 600 to about 1000. The starting powder, fluid medium, and grinding media may be mixed in any proportion. For example, the ratio of the starting valve metal powder to the grinding media may be from about 1:5 to about 1:50. Similarly, the ratio of the volume of the fluid medium to the combined volume of the starting valve metal powder can be from about 0.5: 1 to about 3: 1, in some embodiments from about 0.5: 1 to about 2: 1, and in some embodiments from about 0.5: 1 to about 1: 1. Some examples of mills that can be used with the present invention are described in U.S. Pat. Nos. 5,522,558, 5,232,169, 6,126,097, and 6,145,765.

[0123] Grinding can be carried out for any predetermined duration required to achieve the target specific surface area. For example, the grinding time can range from about 30 minutes to about 40 hours, in some embodiments from about 1 hour to about 20 hours, and in some embodiments from about 5 hours to about 15 hours. Grinding can be carried out at any desired temperature, including at room temperature or elevated temperature. After grinding, the fluid medium can be separated from or removed from the powder, such as by air drying, heating, filtration, evaporation, etc. For example, optionally, the powder is optionally subjected to one or more acid leaching steps to remove metal impurities. Such acid leaching steps are well known in the art and any of various acids can be used, such as inorganic acids (e.g., hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, sulfuric acid, nitric acid, etc.) and organic acids (e.g., citric acid, tartaric acid, formic acid, oxalic acid, benzoic acid, malonic acid, succinic acid, adipic acid, phthalic acid, etc.).

[0124] Although not necessary, any technique known in the art can be used to agglomerate the powder. Such powder can be agglomerated in various ways, such as by carrying out one or more heat treatment steps at a temperature of about 700 °C to about 1400 °C, in some embodiments at a temperature of about 750 °C to about 1200 °C, and in some embodiments at a temperature of about 800 °C to about 1100 °C. The heat treatment can be carried out in an inert atmosphere or a reducing atmosphere. For example, the heat treatment can be carried out in an atmosphere containing hydrogen or a hydrogen-releasing compound (e.g., ammonium chloride, calcium hydride, magnesium hydride, etc.) to partially sinter the powder and reduce the content of impurities (e.g., fluorine). If necessary, agglomeration can also be carried out in the presence of a gettering material (e.g., magnesium). After the heat treatment, the particles can be passivated by gradually introducing air. Other suitable agglomeration techniques are also described in U.S. Patent No. 6,576,038 to Rao, Wolf et al. U.S. Patent No. 6,238,456 to Pathare et al. U.S. Patent No. 5,954,856 to Rerat U.S. Patent No. 5,082,491 to Getz U.S. Patent No. 4,555,268 to Albrecht et al. people U.S. Patent No. 4,483,819 to Getz et al. U.S. Patent No. 4,441,927 to Bates et al. and U.S. Patent No. 4,017,302 to

[0125] Regardless of the specific method used, the resulting powder can have specific properties that enhance its ability to be formed into a capacitor anode. For example, the particles used for the anode can be generally flat. The degree of flatness is generally defined by the "aspect ratio", which is the average diameter or width of the particles divided by the average thickness ("D / T"). For example, the aspect ratio of the particles can be from about 2 to about 100, in some embodiments from about 3 to about 50, and in some embodiments from about 4 to about 30. The specific surface area of ​​the particles can also be about 0.5 m 2 / g to about 10.0m 2 / g, in some embodiments about 0.7m 2 / g to about 5.0m 2 / g, and in some embodiments about 1.0 m 2 / g to about 4.0m 2 / g. The term "specific surface area" is defined in more detail above. In addition, the bulk density (also called the Scott density) is generally about 0.1 grams per cubic centimeter (g / cm 3 ) to about 2 grams per cubic centimeter (g / cm 3 ), in some embodiments about 0.2 g / cm 3 To about 1.5g / cm 3 , and in some embodiments about 0.4 g / cm 3 About 1g / cm 3 . "Bulk density" can be determined using a flow meter funnel and a density cup. More specifically, the sample can be poured into the cup through a funnel until the sample completely fills and overflows the edge of the cup, and then the sample can be scraped flat with a scraper without shaking so that the sample is flush with the top of the cup. The scraped sample is transferred to a balance and weighed to the nearest 0.1 gram to determine the density value. Such an apparatus is commercially available from Alcan Aluminum Corp. of Elizabeth, New Jersey. The average size (e.g., width) of the particles can also be from about 0.1 microns to about 100 microns, in some embodiments from about 0.5 microns to about 70 microns, and in some embodiments from about 1 micron to about 50 microns.

[0126] To facilitate the fabrication of the anode, the powder may also include certain additional components. For example, the powder may optionally be mixed with a binder and / or a lubricant to ensure that the particles adhere sufficiently to each other when they are pressed to form an anode body. Suitable binders can include, for example, poly(vinyl butyral), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl pyrrolidone), cellulose polymers (such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose and methyl hydroxyethyl cellulose), random polypropylene, random polyethylene, polyethylene glycol (for example, Dow Chemical Co.), polystyrene, poly(butadiene / styrene), polyamide, polyimide and polyacrylamide, high molecular weight polyether, copolymers of ethylene oxide and propylene oxide, fluoropolymers (such as polytetrafluoroethylene, polyvinylidene fluoride and fluoroolefin copolymers), acrylic polymers (such as sodium polyacrylate, poly(lower alkyl acrylate), poly(lower alkyl methacrylate) and copolymers of lower alkyl acrylate and methacrylate), and fatty acids and waxes (such as stearic acid and other soapy fatty acids, vegetable waxes, microwaxes (refined paraffin) etc.). The binder can be dissolved and dispersed in a solvent. Exemplary solvents can include water and alcohols etc. When used, the weight percentage of the binder and / or lubricant in the total mass may vary between about 0.1% and about 8%. However, it should be understood that the binder and / or lubricant are not essential to the present invention.

[0127] The resulting powder can be compacted to form a tablet using any conventional powder compacting equipment. For example, a die can be used, which is a single-station compactor comprising a die and one or more punches. Alternatively, an anvil die can be used, which uses only a die and a single lower punch. There are several basic types of single-station die presses, such as cam, elbow / joint and eccentric / crank presses, which have different functions, such as single-action, double-action, floating die, movable platen, opposing ram, spiral, impact, hot pressing, embossing or sizing. The powder can be compacted around the anode lead. The lead can be made of any conductive material, such as tantalum, niobium, aluminum, hafnium, titanium, etc., and their conductive oxides and / or nitrides.

[0128] After pressing, any binder / lubricant can be removed by heating the pressed tablets under vacuum at a certain temperature (e.g., about 150° C. to about 500° C.) for several minutes. Alternatively, the binder / lubricant can also be removed by contacting the pressed tablets with an aqueous solution, such as Bishop et al.Described in U.S. Pat. No. 6,197,252. Thereafter, the pressed sheet is sintered to form a porous, complete substance. The inventors have found that certain sintering conditions can lead to an increase in the specific charge of the resulting anode, as well as an increase in the breakdown voltage of the resulting capacitor. More specifically, the pressed sheet is typically sintered at a temperature of about 800°C to about 2000°C, at a temperature of about 1200°C to about 1800°C in some embodiments, and at a temperature of about 1500°C to about 1700°C for about 5 minutes to about 100 minutes, and in some embodiments for about 8 minutes to about 15 minutes. This can be done in one or more steps. If necessary, sintering can be carried out in an atmosphere that limits the transfer of oxygen atoms to the anode. For example, sintering can be carried out in a reducing atmosphere, such as a vacuum, an inert gas, hydrogen, etc. The pressure of the reducing atmosphere can be about 10 Torr to about 2000 Torr, about 100 Torr to about 1000 Torr in some embodiments, and about 100 Torr to about 930 Torr in some embodiments. A mixed gas of hydrogen and other gases (e.g., argon or nitrogen) may also be used. When using flaky particles, the flaky particles may be more able to withstand the high sintering temperatures and prolonged sintering times typically used in forming an anode, and produce a porous sintered body with low shrinkage and a large specific surface area.

[0129] During sintering, the tablet shrinks due to the growth of metallurgical bonds between particles. Since shrinkage usually increases the density of the tablet, a lower pressing density ("green compact") can be used, so that the desired target density can still be achieved. For example, the target density of the tablet after sintering is usually about 5 grams per cubic centimeter to about 8 grams per cubic centimeter. However, due to the existence of shrinkage, the tablet does not need to be pressed into such a high density, on the contrary, it can be pressed into a density of less than about 6.0 grams per cubic centimeter, about 4.5 grams per cubic centimeter to about 5.5 grams per cubic centimeter in some embodiments. Among other aspects, being able to use a lower green compact density can significantly save costs and improve processing efficiency. It should be understood that the compression density across the tablet is not always uniform, especially if the compression occurs in the direction perpendicular to the longitudinal axis of the lead. That is, the compression density is determined by dividing the amount of material by the volume of the pressed tablet. The volume of the tablet is proportional to the compression length in the direction perpendicular to the longitudinal axis of the lead. The density is inversely proportional to the compression length. Thus, the compressed length at those locations adjacent to the leads is substantially shorter than the compressed length at the rest of the compact. Likewise, the compaction density at those locations adjacent to the leads is greater. For example, the density at those locations of the compact adjacent to the leads is typically at least about 10% higher, and in some cases at least about 20% higher, than the compaction density at the rest of the compact.

[0130] Due to the thin nature of planar anodes, it is sometimes desirable to control the manner in which the anode lead is inserted to limit the extent to which the lead may be pulled out of the anode due to stresses applied during manufacturing. For example, in one embodiment, at least a portion of the lead in the anode is bent at an angle relative to the longitudinal axis of the lead. This "bend" reduces the ease with which the lead can be pulled out in the longitudinal direction after the anode has been pressed and sintered. For example, referring to Figure 2 and Figure 3 , shows an embodiment of a planar anode 200 including an anode lead 220. The anode lead includes a first portion 221 extending from the anode 200 in a longitudinal direction ("y" direction). In the anode body, the lead 200 also includes a second portion 222 bent at an angle "α" relative to the first portion 221. The angle "α" is typically about 40° to about 120°, about 60° to about 110° in some embodiments, and about 80° to about 100° (e.g., about 90°) in some embodiments. Such a curved configuration can be achieved in a variety of different ways. For example, in one embodiment, the powder can be partially filled into a die, and then the "pre-bent" anode lead can be inserted into the die. Thereafter, the mold can be filled with powder and the entire assembly can be pressed into a tablet.

[0131] In addition to the geometric configuration of the anode lead, the extent to which the anode lead is inserted into the anode can also be controlled to help minimize the likelihood of it being pulled out during manufacturing. That is, the deeper the anode lead is inserted, the less likely it is to be pulled out of the anode. Of course, inserting the lead too deeply may change the uniformity of the compaction density, which can affect the electrical properties produced by the anode. In this regard, the inventors have found that the ratio of the length of the anode lead inserted to the total length of the anode is generally from about 0.1 to about 0.6, and in some embodiments from about 0.2 to about 0.5. For example, in Figure 2 In the middle, the length "L 1 ” represents the length of the anode lead 220 inserted into the anode 200, and the length “L” represents the entire length of the anode 200. In some cases, the length “L” of the anode 200 can be in the range of about 1 mm to about 80 mm, in some embodiments in the range of about 10 mm to about 60 mm, and in some embodiments in the range of about 20 mm to about 50 mm. Similarly, the length “L 1 " can be from about 1 mm to about 40 mm, in some embodiments from about 2 mm to about 20 mm, and in some embodiments from about 5 mm to about 15 mm. The width "W" of the anode can also be from about 0.05 mm to about 40 mm, in some embodiments from about 0.5 mm to about 25 mm, and in some embodiments from about 2 mm to about 10 mm.

[0132] The thickness of the anode is usually small to improve the electrical performance and volumetric efficiency of the resulting capacitor. Figure 3 In the embodiment, the thickness of the planar anode 200 is represented by the dimension "H". Typically, the thickness of the anode is about 5 mm or less, in some embodiments, about 0.05 mm to about 4 mm, and in some embodiments, about 0.1 mm to about 3.5 mm. The ratio of the length of the anode to the thickness of the anode is about 5 to about 50, in some embodiments, about 6 to about 30, and in some embodiments, about 7 to about 20. Although in Figure 2 shaped, it should be understood that the anode may have any other desired shape, such as square, rectangular, circular, oval, triangular, etc. Polygonal shapes having more than four (4) sides (e.g., hexagons, octagons, heptagons, pentagons, etc.) are particularly desirable due to their relatively high surface areas.

[0133] The anode also includes a dielectric formed by anodizing the sintered anode ("anodizing") such that a dielectric layer is formed on and / or within the anode. For example, a tantalum (Ta) anode can be anodized to form tantalum pentoxide (Ta). 2 O 5 ). Typically, anodization is performed by first applying a solution to the anode, such as immersing the anode in an electrolyte. Aqueous solvents (e.g., water) and / or non-aqueous solvents (e.g., ethylene glycol) can be used. In order to enhance conductivity, compounds that can dissociate in a solvent to form ions can be used. Examples of such compounds include, for example, acids, such as those described below with respect to an electrolyte. For example, an acid (e.g., phosphoric acid) can account for about 0.01 wt.% to about 5 wt.% of the anodizing solution, about 0.05 wt.% to about 0.8 wt.% in some embodiments, and about 0.1 wt.% to about 0.5 wt.% in some embodiments. A mixture of acids can also be used if necessary.

[0134] A current is passed through the anodizing solution to form a dielectric layer. The value of the formation voltage controls the thickness of the dielectric layer. For example, the power supply can first be set to a constant current mode until the desired voltage is reached. Thereafter, the power supply can be switched to a constant potential mode to ensure that the desired dielectric thickness is formed over the entire surface of the anode. Of course, other known methods, such as pulse or step constant potential methods, can also be used. The temperature of the anodizing solution can range from about 10°C to about 200°C, in some embodiments from about 20°C to about 150°C, and in some embodiments from about 30°C to about 100°C. The formed dielectric layer can be formed on the surface of the anode and in the pores of the anode. When a powder is used, the specific characteristics of the powder can enable the resulting anode to achieve a high specific charge even at the high formation voltage often used in the present invention. For example, within the range noted above, the specific charge of the anode may still be able to reach about 2,000 μF*V / g to about 20,000 μF*V / g, in some embodiments about 5,000 μF*V / g to about 15,000 μF*V / g or more, and in some embodiments about 8,000 μF*V / g to about 12,000 μF*V / g.

[0135] The particular manner in which the components are incorporated into the capacitor is not critical and may be accomplished using a variety of techniques. However, in most embodiments, the anode is positioned within the housing. For example, referring to Figure 1 and Figure 4 , showing that the capacitor 10 includes Figure 2 and Figure 3 One embodiment of an anode 200 is shown in FIG. Although only one anode is shown, it should be understood that multiple anodes (eg, stacked) may be used, such as Ziarniak et al. 7,483,260. In the illustrated embodiment, the anode 200 can be positioned within a housing 12 comprised of a first housing member 14 and a second housing member 16. The first housing member 14 has a side wall 18 connected to a peripheral side wall 20 that extends to an edge 22. The second housing member 16 is plate-shaped and includes a second face wall 24 having a peripheral edge 26. The housing member 14 and the housing member 16 can be hermetically sealed together by welding (e.g., laser welding) the overlapping edges 22 and 26 that are in contact with each other. The housing member 14 and / or the housing member 16 can be similar to the metal substrate described above so that a conductive polymer coating (not shown in the figure) can be deposited on its inner surface. Alternatively, a separate metal substrate can be located adjacent to the housing member 14 and / or the housing member 16 and coated with a conductive polymer coating.

[0136] Although not shown, one or more separators can be used that help isolate the anode and the cathode coated with the conductive polymer from each other. Examples of suitable materials for this purpose include, for example, porous polymer materials (e.g., polypropylene, polyethylene, etc.), porous inorganic materials (e.g., glass fiber felt, porous cellophane, etc.), ion exchange resin materials, etc. Specific examples include ionic perfluorosulfonic acid polymer membranes (e.g., Nafion from E.I. DuPont deNemeours & Co.) TM The separators include sulfonated fluorocarbon polymer membranes, polybenzimidazole (PBI) membranes, and polyether ether ketone (PEEK) membranes. Although preventing the anode and cathode from making direct contact, the separator allows the ionic current of the electrolyte to flow to the electrodes.

[0137] In addition, although not shown, it should be understood that a capacitor according to the present disclosure may include more than one anode, such as a multi-anode structure. Thus, although only one anode is shown, it should be understood that multiple anodes (e.g., stacked) may be employed, for example, as described in U.S. Pat. No. 7,483,260 to Ziarniak et al., or multiple anodes may be deployed with different cross-sections that combine to form a cross-section of a corresponding housing, for example, as described in U.S. Pat. No. 9,870,868 to Laforge et al.

[0138] A feedthrough 30 may also be used, which electrically insulates the anode lead 200 from the housing 12. The feedthrough 30 extends from inside the housing 12 to outside the housing 12. A hole 34 may be provided on the peripheral sidewall 20 of the housing member 14, through which the feedthrough 30 passes. For example, the feedthrough 30 may be a glass-to-metal seal ("GTMS") comprising a ferrule (not shown) having an internal cylindrical hole with a constant inner diameter. Thus, the insulating glass may provide an airtight seal between the hole and the anode lead 200 passing therethrough. After assembly and sealing (e.g., welding), the electrolyte may optionally be introduced into the housing through a charging port. The capacitor may be filled by placing it in a vacuum chamber so that the charging port extends into a reservoir of the electrolyte. When the chamber is evacuated, the pressure inside the capacitor decreases. When the vacuum is released, the pressure inside the capacitor re-equilibrates, and the electrolyte is sucked into the capacitor through the charging port.

[0139] Regardless of the specific configuration of the capacitor of the present invention, the capacitor of the present invention can exhibit excellent electrical properties. For example, the capacitor can exhibit high volumetric efficiency, such as about 50,000 μF*V / cm2 measured at a frequency of 120 Hz and room temperature (e.g., 25° C.). 3 To about 300,000μF*V / cm 3 , in some embodiments about 60,000 μF*V / cm 3 To about 200,000μF*V / cm 3 , and in some embodiments about 80,000 μF*V / cm 3 To about 150,000μF*V / cm 3 Volumetric efficiency is determined by multiplying the component's formation voltage by its capacitance and then dividing the resulting value by the volume of the component. For example, for a component with a capacitance of 520 μF, the formation voltage might be 175 volts, resulting in a product of 91,000 μF*V. If the volume occupied by the component is approximately 0.8 cm 3 , the resulting volumetric efficiency is about 113,750 μF*V / cm 3 .

[0140] Capacitors can also exhibit high energy density, making them suitable for high pulse applications. Energy density is usually calculated according to the formula E = 1 / 2*CV 2 Where C is the capacitance in farads (F) and V is the operating voltage of the capacitor in volts (V). For example, the capacitance can be measured using a capacitance meter (e.g., a Keithley 3330 precision LCZ meter with Kelvin leads, 2 volts bias, 1 volt signal) at an operating frequency of 10 Hz to 120 Hz (e.g., 120 Hz) and a temperature of 25° C. For example, a capacitor may exhibit approximately 2.0 joules per cubic centimeter (2.0 J / cm 3 ) or higher, in some embodiments about 3.0 J / cm 3 , in some embodiments about 3.5 J / cm 3 To about 10.0J / cm 3 , and in some embodiments about 4.0 J / cm 3 To about 8.0J / cm 3 Similarly, the capacitance may be about 1 millifarad per square centimeter (“mF / cm 2 ”) or higher, in some embodiments about 2 mF / cm 2 or higher, in some embodiments about 5 mF / cm 2 To about 50mF / cm 2, and in some embodiments about 8 mF / cm 2 To about 20mF / cm 2 The capacitor may also exhibit a relatively high "breakdown voltage" (the "BDV" voltage at which the capacitor fails), such as about 180 volts or more, in some embodiments about 200 volts or more, such as about 250 volts or more, such as about 300 volts or more, such as about 350 volts or more, such as about 375 volts or more, or any range between these values, such as in one aspect, about 350 volts to about 425 volts.

[0141] The electrolytic capacitors of the present invention can be used in various applications, including but not limited to: medical devices, such as implantable defibrillators, pacemakers, cardioverters, neurostimulators, drug delivery devices, etc.; automotive applications; military applications, such as radar systems; consumer electronics, such as radios, televisions, etc. For example, in one embodiment, the capacitor can be used in an implantable medical device configured to provide therapeutic high voltage (e.g., between about 500 volts and about 850 volts, or ideally, between about 600 volts and about 900 volts) treatment to a patient. The device can include a hermetically sealed and biologically inert container or housing. One or more leads are electrically coupled between the device and the patient's heart through a vein. The cardiac electrodes are also configured to sense cardiac activity and / or provide voltage to the heart. At least a portion of the lead (e.g., the end of the lead) can be configured to be adjacent to or in contact with one or more of the ventricles and atria of the heart. The device can also include a capacitor bank, which typically includes two or more capacitors connected in series and coupled to a battery, which is located inside or outside the device and supplies energy to the capacitor bank. Due in part to the high conductivity, the capacitors of the present invention have excellent electrical properties and are therefore suitable for use in capacitor banks for implantable medical devices.

[0142] The present invention may be better understood with reference to the following examples.

[0143] Example 1

[0144] The electrolyte solution used to form the working electrolyte used in the capacitor of the present invention was prepared according to the following table:

[0145]

[0146] According to Table 1, the electrolyte (A) and the additive (B) form a working electrolyte. As shown, Sample 1 and Sample 2 each contain a gelling activator as described herein. The conductivity is measured at room temperature (22° C. to 25° C.).

[0147] Table 1

[0148] Sample 1 Sample 2 A. Electrolyte (wt.%) 81.27 81.29 B. Additives (wt.%) 18.69 18.7 Sorbitan monostearate (wt.%) 0.4 0 3-Aminopropyltrimethoxysilane (wt.%) 0 0.01 pH 6.63 6.55 Conductivity (mS / cm) 24.05 24.01 BDV 375 403

[0149] To form a working electrolyte, the components of Part A are first combined and ultrasonically treated to mix the materials. The components of Part B are also combined and mixed, then mixed with the corresponding gelling activator, and ultrasonically treated to mix the materials. After mixing, Part A and Part B are combined and tested as shown in Table 1. In addition, the gelling properties of the additives and gelling activators are tested according to Tables 2 and 3, wherein each sample maintains the above-mentioned Part A and Part B, and only the amount of the gelling activator is changed. For each of the samples in this article, the SMS sample gelled at 37°C, the APTMS sample gelled at room temperature, and all performance tests were performed at room temperature (22°C to 25°C).

[0150] Table 2

[0151]

[0152] Table 3

[0153]

[0154] As shown, the gelation activator according to the present invention initiates gelation at low concentrations and can be varied to adjust the gelation time. In addition, as shown in Table 2, according to the process of this example, single fumed silica (0wt.% SMS, as a control in Tables 2 and 3) does not initiate gelation.

[0155] Example 2

[0156] An open cell capacitor was prepared using the electrolyte of Example 1 as follows. The anode with leads was placed in a plastic vial, and the working electrolyte discussed in Example 1 was added to the vial so that the electrolyte just covered the anode within one hour after the electrolyte was formed. The vial containing the anode, cathode and electrolyte was placed in a vacuum chamber and evacuated to about 30 inches of Hg for 2 to 4 hours to allow the electrolyte to penetrate into the porous anode.

[0157] The test cells were assembled as follows: a rectangular sheet of cellulose separator (e.g., PXW7D separator from Nippon Kodoshi Corporation) with dimensions (length and width) approximately 10% larger than the cathode foil was pressed onto the electrolyte-coated cathode so that the separator extended beyond all four edges of the cathode foil, and then the separator was trimmed to the size of the cathode, followed by sandwiching the anode, which had previously been soaked in electrolyte, between the two separator-cathode foils. The entire cathode-separator-anode-separator-cathode assembly was filled with working electrolyte, gently secured together, and then placed back under vacuum for 30 minutes to remove entrapped air. Each of the following samples was prepared from the same working electrolyte stock and made into individual capacitor elements according to the above process.

[0158] The capacitance and equivalent series resistance (ESR) of the capacitor unit were tested at a frequency of 40Hz to 10,000Hz using commercially available instruments (e.g., Agilent 4294A precision impedance analyzer), and the capacitor unit was subjected to a series of charge and discharge cycles using different load resistors to evaluate the energy capacity of the device. Specifically, the open cell capacitor was charged to a predetermined voltage using a Keithley 2400 digital source meter at a current of 5 mA to 10 mA, and then the open cell capacitor was discharged to a load resistor of 10,000 ohms or 50 ohms. The discharge voltage at both ends of the resistor was recorded using a Tektronix 784A oscilloscope to change over time. The cumulative energy was calculated from the measured discharge voltage by integrating the voltage squared by the load resistance relative to time. In addition, the capacitor unit was charged to a predetermined voltage, and then the voltage was maintained for up to 300 seconds, while monitoring the voltage at both ends of the 1,000 ohm series resistor, i.e., the leakage current. The results are listed in Tables 4 and 5 below.

[0159] Table 4

[0160] Sample 1-1 Sample 1-2 Capacitance(μF) 567 578 1.07 1.09 DCL(microohm) 483 502 Energy transferred (joules) 20.65 21.08

[0161] Table 5

[0162] Sample 2-1 Sample 2-2 Sample 2-3 Sample 2-4 Capacitance(μF) 578.1 577.0 578.3 578.2 ESR(Ohm) 1.26 1.31 1.34 1.24 DCL(microohm) 677 542 529 960 Energy transferred (joules) 21.05 21.11 21.08 21.19

[0163] Without departing from the spirit and scope of the present invention, those of ordinary skill in the art may practice these and other modifications and variations of the present invention. In addition, it should be understood that the aspects of the various embodiments may be replaced with each other in whole or in part. In addition, those of ordinary skill in the art will appreciate that the foregoing description is only exemplary and is not intended to limit the present invention, which is further described in the appended claims.

Claims

1. A wet electrolytic capacitor, the wet electrolytic capacitor include: an anode comprising an anodic oxide pressed pellet formed from pressed and sintered powder; cathode; as well as a working electrolyte in communication with the anode and the cathode, wherein the working electrolyte is in gel form and has a pH of about 5.0 to about 8.0; and The wet electrolytic capacitor exhibits a leakage current (DCL) of about 625 micro-ohms or less measured at a temperature of 37° C. and a rated voltage.

2. The wet electrolytic capacitor according to claim 1, in, The working electrolyte includes an ammonium salt of an organic acid, inorganic oxide particles, an acid, a gelling activator, and a solvent system including water.

3. The wet electrolytic capacitor according to claim 2, in, The gelation activator is a self-assembling gelator, a cross-linking gelator or a combination thereof.

4. The wet electrolytic capacitor according to claim 2, in, The gelling activator comprises: sugar or its derivatives, vitamins or their derivatives, glycerol or its derivatives, or a combination thereof and C 1 -C 36 An ester formed from a fatty alkanoic acid; an organometallic compound; or any combination of the ester and the organometallic compound.

5. The wet electrolytic capacitor according to claim 4, in, The organometallic compound has the following general formula: in, M is an organometallic atom, preferably, wherein M is silicon; R 1 , R 2 and R 3 are independently alkyl or hydroxyalkyl, wherein R 1 , R 2 and R 3 At least one of them is a hydroxyalkyl group; n is an integer from 0 to 8; X is an organic functional group or an inorganic functional group.

6. The wet electrolytic capacitor according to claim 4, in, The organometallic compound is a primary amine, a secondary amine, a tertiary amine, or a combination thereof. Preferably, the organometallic compound is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltri(methoxy-ethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane; or a combination thereof.

7. The wet electrolytic capacitor according to claim 4, in, The sugar or its derivative, the vitamin or its derivative, the glycerol or its derivative, or a combination thereof and C 1 -C 36 The ester formed from fatty alkanoic acid is ascorbyl alkanoate, sorbitan alkanoate, monoalkanoic acid triglyceride, sucrose alkanoate, or a combination thereof.

8. The wet electrolytic capacitor according to claim 7, in, The gelling activator is ascorbyl palmitate, ascorbyl caprate, ascorbyl laurate, ascorbyl caprylate, ascorbyl myristate, ascorbyl oleate, sorbitan monostearate, sorbitan laurate, sorbitan caprylate, sorbitan myristate, sorbitan oleate, glycerol palmitate, glycerol monocaprate, glycerol monocaprylate, glycerol monostearate, glycerol monooleate, sucrose palmitate, sucrose monocaprate, sucrose monostearate, sucrose laurate, sucrose caprylate, sucrose myristate, sucrose oleate, or a combination thereof.

9. The wet electrolytic capacitor according to claim 4, in, The gelling activator is a sorbitan alkanoate, preferably sorbitan monostearate or 3-aminopropyltrimethoxysilane.

10. The wet electrolytic capacitor according to claim 2, in, The gelling activator is present in the working electrolyte in an amount of about 0.01 wt.% to about 2 wt.%, preferably about 0.05 wt.% to about 0.1 wt.%, based on the weight of the working electrolyte.

11. The wet electrolytic capacitor according to claim 2, in, The solvent system also includes a co-solvent.

12. The wet electrolytic capacitor according to claim 11, in, The co-solvent is ethylene glycol, wherein the ethylene glycol is present in the working electrolyte.

13. The wet electrolytic capacitor according to claim 11, in, Water comprises about 35 wt. % to about 85 wt. % of the electrolyte, and ethylene glycol comprises about 25 wt. % or less of the working electrolyte.

14. The wet electrolytic capacitor according to claim 1, in, The working electrolyte exhibits an electrical conductivity of about 10 millisiemens per centimeter to about 100 millisiemens per centimeter measured at a temperature of 25°C.

15. The wet electrolytic capacitor according to claim 1, in, The anode is planar and has a thickness of about 5 mm or less, preferably, wherein the planar anode has a D-shape or a cylindrical shape.

16. The wet electrolytic capacitor according to claim 1, in, The powder is formed from tantalum particles, preferably, wherein the tantalum particles are plate-like particles having an aspect ratio of about 2 to about 100, and / or wherein the cathode comprises a metal substrate, optionally, the metal substrate comprises titanium.

17. The wet electrolytic capacitor according to claim 1, further comprising a conductive polymer layer disposed on the cathode. in, The conductive polymer is a substituted polythiophene, and preferably, the substituted polythiophene is poly(3,4-ethylenedioxythiophene).

18. An implantable medical device comprising the wet electrolytic capacitor according to claim 1.

19. A working electrolyte for a wet electrolytic capacitor, the working electrolyte comprising about 1 wt.% to about 40 wt.% of at least one organic acid ammonium salt, about 0.01 wt.% to about 10 wt.% of at least one acid, about 0.5 wt.% to about 20 wt.% of inorganic oxide particles, about 0.01 wt.% to about 2 wt.% of a gelling activator, about 30 wt.% to about 80 wt.% of water, and about 5 wt.% to about 40 wt.% of at least one co-solvent, in, The working electrolyte is in a gel form and has a pH value of about 5.0 to about 8.0, and the working electrolyte has a conductivity of about 10 millisiemens per centimeter to about 100 millisiemens per centimeter measured at a temperature of 25°C.

20. The working electrolyte according to claim 19, in, The gelling activator comprises: sugar or its derivatives, vitamins or their derivatives, glycerol or its derivatives, or a combination thereof and C 1 -C 36 An ester formed from a fatty alkanoic acid; an organometallic compound; or any combination of the ester and the organometallic compound.

21. The working electrolyte according to claim 20, in, The organometallic compound has the following general formula: in, M is an organometallic atom, preferably, wherein M is silicon; R 1 , R 2 and R 3 are independently alkyl or hydroxyalkyl, wherein R 1 , R 2 and R 3 At least one of them is a hydroxyalkyl group; n is an integer from 0 to 8; X is an organic functional group or an inorganic functional group, and / or Wherein, the sugar or its derivative, the vitamin or its derivative, the glycerol or its derivative, or a combination thereof and the C 1 -C 36 The ester formed from fatty alkanoic acid is ascorbyl alkanoate, sorbitan alkanoate, monoalkanoic acid triglyceride, sucrose alkanoate, or a combination thereof.

22. A method for forming a wet electrolytic capacitor, the method include: forming a mixture comprising an ammonium salt of an organic acid, inorganic oxide particles, a gelling activator, an acid, and a solvent system comprising water; Initiating gelation of the mixture so that the mixture exhibits a first phase angle δ of about 50° to 90°; placing the gelled mixture in communication with an anode, a cathode, or both, wherein the anode comprises an anodized pellet formed from a pressed and sintered powder; and Subsequently, the mixture is further gelled to form a working electrolyte, the working electrolyte exhibiting a second phase angle δ of 0° to about 20°, wherein the working electrolyte also has a pH of about 5.0 to about 8.0, The working electrolyte exhibits the second phase angle during a period of about 4 hours to about 24 hours.

23. The method according to claim 22, in, The amount of the gelling activator used in the working electrolyte is such that the second phase angle is exhibited between about 6 hours and about 12 hours.

24. The method according to claim 22, in, The mixture was subjected to ultrasonic dispersion.

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