Hybrid polymer capacitor

Abstract

The present invention relates to a hybrid polymer capacitor (100) comprising several layers between an anode layer (1) and a cathode layer (6), the hybrid polymer capacitor (100) comprising a non-hydrated metal oxide layer (2) having a thickness of at least 100 nm in the stacking direction, a hydrated metal oxide layer (3) arranged on the surface of the non-hydrated metal oxide layer (2), and a liquid electrolyte having a conductivity of at least 200 μS / cm at 30° C. and a water content of at least 0.5%, the hydrated metal oxide layer and the non-hydrated metal oxide layers (2, 3) being impregnated with the liquid electrolyte.

Description

Technical Field

[0001] The present invention relates to a hybrid polymer capacitor.

Background Art

[0002] Hybrid polymer capacitors are used in electronic circuits where a high capacitance and voltage range, low ESR, enhanced ripple current capability, or wide operating temperature range are required in a compact design. Capacitor manufacturers can provide hybrid polymer capacitors with a low voltage range. For example, Patent Document 1 or Patent Document 2 discloses state-of-the-art hybrid polymer capacitors. The capacitors are limited to low operating voltages. The maximum breakdown voltages disclosed total 119V.

[0003] When an operating voltage exceeding 150V is used, hybrid polymer capacitors are highly sensitive to short circuits (breakdowns) between the anode and cathode electrodes. Therefore, other capacitor types such as film capacitors are used in electronic circuits at operating voltages higher than 150V.

[0004] So far, capacitor manufacturers have not been able to develop and produce high-voltage hybrid polymer capacitors because they have not been reliable enough for use in commercial electronic circuits. However, for example, for electric vehicle chargers and inverters, capacitor voltage classes of 400V or higher become relevant.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] The present invention provides an improved hybrid polymer capacitor, which includes several layers positioned between an anode layer and a cathode layer.

[0007] The anode layer forms the anode electrode of the capacitor, and the cathode layer forms the cathode electrode of the capacitor.

[0008] Furthermore, a non-hydrated metal oxide layer is provided. The non-hydrated metal oxide layer, also referred to as the oxide layer below, has a thickness of at least 100 nm in the stacking direction. In this specification, the stacking direction is the direction in which the anode layer and cathode layer face each other and several layers are stacked. Therefore, the stacking direction is also the direction of the electric field applied to the capacitor and the direction of the current in the case of capacitor breakdown.

[0009] In this specification, the oxide layer serves as an electrical insulating layer between the anode and the cathode.

[0010] In a preferred embodiment, the thickness of the non-hydrated metal oxide layer may be greater than 110 nm or greater than 120 nm.

[0011] In a preferred embodiment, the anode comprises an anode foil containing one or more anode layers, and the cathode comprises a cathode foil containing one or more cathode layers. Both the anode and the cathode may contain a metal, preferably aluminum. Aluminum has advantageous electrochemical properties suitable for applications in capacitors.

[0012] The anode and cathode layers can further provide a porous structure with advantageously large surface areas. Pores may be actively etched in the anode or cathode material. In particular, the surface of the cathode layer may include a roughened, spongy, or grape-like structure to increase the surface area.

[0013] The capacitor further comprises a liquid electrolyte having a conductivity of at least 200 μS / cm and a water content of at least 0.5% (for the electrolyte, the percentage is defined as w / w% (weight of water / total weight of electrolyte)) as measured at 30°C. The conductivity of the liquid electrolyte may be significantly higher than 200 μS / cm. In particular, the conductivity may be 2500 μS / cm in total at 30°C. The surface of the oxide layer is impregnated with the liquid electrolyte.

[0014] The minimum thickness of the electrically insulating oxide layer is essential to providing a specific breakdown voltage for the capacitor. The breakdown voltage is determined experimentally as follows: To determine the breakdown voltage, a 1000Ω series resistor is provided to the capacitor, and it is subjected to a voltage increase starting from 0V in 1V / s steps. The resulting current is measured. The voltage value at which the resulting current exceeds 500μA is identified as the breakdown voltage.

[0015] The oxide layer may contain separate voids having diameters in the nanometer range. Such voids may be densely distributed throughout the oxide layer. Increasing the thickness of the oxide layer may result in a greater number of voids, and the void density may also increase. During operation, the separate voids may condense to form larger void structures that can reach the surface of the oxide layer.

[0016] Therefore, conductive materials such as polymer nanoparticles that may be provided on the surface of the oxide layer may penetrate the void and form conductive paths through the oxide layer, which could cause a decrease in the breakdown voltage of the capacitor.

[0017] A specific liquid electrolyte having a conductivity of at least 200 μS / cm measured at 30°C and a water content of at least 0.5% is suitable for improving the oxide layer during the operation of the capacitor due to its oxidizing ability. Thus, the formation of unwanted void structures that could impair the electrical insulation properties of the oxide layer and lower the breakdown voltage is at least suppressed or even avoided.

[0018] The liquid electrolyte is impregnated into the layers of the capacitor, particularly the oxide layer. The electrolyte has the ability to oxidize the anode metal to improve the oxide layer and to avoid or close unwanted void structures within the oxide layer. The water content of the electrolyte is preferably 0.5% to 7% or 0.5% to 5%, more preferably 0.5% to 3%. Effective re-oxidation is improved by the optimized water content of the liquid electrolyte as described above.

[0019] Therefore, the capacitor can withstand voltages exceeding 150V, preferably exceeding 250V, and more preferably at least 400V or 450V.

[0020] Furthermore, the spark voltage at which the liquid electrolyte begins to form a thicker oxide layer is preferably higher than 400V at 85°C.

[0021] The spark voltage is a characteristic of the electrolyte measured in a beaker above the electrolyte, which has no separator layer and only a defined distance between the anode and cathode foils. The breakdown voltage is higher than the spark voltage because the separator layer of the capacitor limits the total amount of electrolyte and restricts the movement of ions in the electrolyte.

[0022] Hybrid polymer capacitors are less expensive than film capacitors because they are smaller components for the same capacitance, and because of their superior heat dissipation capabilities, which leads to more economical and compact heat sink and cooling unit designs. The hybrid polymer capacitor according to the present invention can replace film capacitors at operating voltages exceeding 150V.

[0023] Furthermore, the hybrid polymer capacitor can enhance reliability due to its described self-healing properties.

[0024] In a preferred embodiment, the anode layer contains aluminum and the oxide layer contains aluminum oxide Al2O3, also known as alumina. Preferably, the layer consists of these materials.

[0025] Aluminum has advantageous electrochemical properties. Furthermore, alumina is a well-known good electrical isolator and is suitable for application in capacitors.

[0026] In one embodiment, the oxide layer is applied directly to the surface of the anode layer.

[0027] In the stacking direction, the oxide layer and the anode layer are adjacent to each other. The oxide layer may contain an oxidized anode material. In particular, the oxide layer may be formed by oxidizing the anode layer with a strong forming electrolyte, such as an aqueous dicarboxylic acid or borate type solution, which is different from the liquid electrolyte used during the operation of the capacitor in the manufacturing process.

[0028] Furthermore, some layers of the capacitor include a hydrated metal oxide layer disposed on the surface of a non-hydrated metal oxide layer. The non-hydrated metal oxide layer is disposed on the surface of the oxide layer opposite the anode in the stacking direction. The hydrated metal oxide layer may have a thickness of at least 10 nm in the stacking direction.

[0029] The hydrated oxide layer serves as a protective layer against the non-hydrated oxide layer. The non-hydrated oxide layer is formed by applying an aqueous solution of an oxidation electrolyte during the manufacturing process. The hydrated metal oxide layer can be formed by a specific hydration process, such as boiling, using a suitable forming salt as a pretreatment and performing a special temperature profile treatment during the annealing step of the anode foil.

[0030] In particular, the hydrated oxide layer prevents, at least partially, the penetration of conductive polymer nanoparticles into the bulk of the oxide layer, thus preventing sparking and increasing the breakdown voltage. Combined with the oxidizing capacity of the liquid electrolyte, the hydrated oxide layer thus prevents electrical short circuits through the oxide layer.

[0031] The hydrated oxide layer is less dense but more homogeneous than the unhydrated oxide layer. Therefore, the preferred thickness of the hydrated oxide layer is at least 10 nm.

[0032] In particular, the hydrated oxide layer may contain hydrated alumina, which is hydrated Al2O3, i.e., Al2O3·xH2O, where x is between 0.1 and 3.0 (including the limiting value).

[0033] In one embodiment, the unhydrated oxide layer, the hydrated oxide layer, or both oxide layers are doped with phosphorus. For example, the phosphorus anion PO4 3- However, it is added to the oxide layer formation solution. The minimum atomic percentage of phosphorus in the oxide layer is preferably at least 0.01%. Anions are added to stabilize the layer structure, avoid the formation of unwanted void structures, and thus improve the breakdown characteristics of the capacitor.

[0034] In one embodiment, the non-hydrated oxide layer, which is preferably an alumina layer, includes a stack of amorphous oxide layers and crystalline oxide layers, particularly an amorphous alumina layer and a crystalline alumina layer.

[0035] In a preferred embodiment, the oxide layer comprises an amorphous Al2O3 layer and a crystalline γ-Al2O3 layer, with a layer thickness ratio of >0.1 (thickness of the crystalline layer / thickness of the amorphous layer). The amorphous layer may be coated directly onto the surface of the anode layer. The crystalline layer may be coated directly onto the surface opposite the amorphous layer. The amorphous layer has fewer structural defects than the crystalline layer and therefore better sealing properties, but the crystalline layer can be coated to a greater thickness, so the breakdown voltage of the capacitor can be increased by the combination of both layers.

[0036] In one embodiment, the rated voltage of the capacitor is greater than 150V, preferably greater than 250V. More preferably, the rated voltage of the capacitor is at least 400V or 450V.

[0037] Therefore, the present invention enables the use of hybrid polymer capacitors at extended rated voltages higher than 150V. Compared to other types of capacitors, hybrid polymer capacitors also offer a superior capacitance-to-volume ratio, low ESR (equivalent series resistance) at high frequencies, and low ESR at low temperatures.

[0038] Hybrid polymer capacitors, due to their small component size and superior heat dissipation capabilities, allow for more economical and compact designs of heat sinks and cooling units, thus fulfilling the requirements for miniaturization and cost reduction. Therefore, for the same capacitance, hybrid polymer capacitors are smaller and less expensive than, for example, film capacitors.

[0039] In one embodiment, a polymer layer containing a conductive polymer is placed between one or more oxide layers, which are an unhydrated oxide layer and an arbitrary hydrated oxide layer, and a cathode layer on the opposite side.

[0040] The polymer effectively functions as a layer in the cathode of the capacitor.

[0041] The polymer is preferably applied by impregnating the capacitor layer with a dispersion of the conductive polymer. This ensures that the conductive polymer nanoparticles are applied to the outer surface of the oxide layer that is not facing the anode or another oxide layer. The applied nanoparticles then aggregate to form a polymer layer.

[0042] Furthermore, polymer nanoparticles can penetrate the hydrated oxide layer and the unhydrated oxide layer, as well as other adjacent layers such as the separator layer or cathode layer, thereby increasing the conductivity of these layers.

[0043] The polymer layer preferably comprises a PEDOT:PSS polymer material, which means poly(3,4-ethylenedioxythiophene)polystyrene sulfonate, a polymer mixture of two ionomers (PEDOT and PSS). This material exhibits desirable properties for use as a conductive polymer in capacitors.

[0044] The properties of the hybrid polymer material PEDOT:PSS result in a favorable low ESR level for capacitors, even at low temperatures.

[0045] Preferably, a separator layer having a separator withstand factor of at least 5% is placed between the polymer layer and the cathode layer. More preferably, the resistivity is at least 15%.

[0046] The separator layer is sandwiched between the anode layer and the cathode layer to prevent direct contact between the electrodes.

[0047] The breakdown phenomenon of a capacitor depends not only on the capacitor's rated voltage but also on the characteristics of the insulating oxide layer and separator.

[0048] The characteristics of the separator layer are, at a minimum, its material type, density, and thickness. More specifically, these characteristics are determined by the separator resistivity, which determines the breakdown voltage.

[0049] The separator can be impregnated with a liquid electrolyte to fill all the pores within the separator that the polymer nanoparticles could not reach during the polymer impregnation process.

[0050] Furthermore, after impregnation, the electrolyte fills the pores in the anode and cathode foils. In this way, since there are no or minimal voids remaining within the electrodes, the capacitance of the capacitor can be maximized.

[0051] In one embodiment, the separator layer has a minimum thickness of 50 μm.

[0052] In one embodiment, the density of the separator layer is at least 0.30 g / cm³. 3 That is the case.

[0053] The aforementioned characteristics of both separator layers increase the resistivity of the separator layer, and therefore the breakdown voltage of the capacitor.

[0054] In this specification, resistivity is defined as the basic weight of the separator divided by the rated voltage of the capacitor.

[0055] The basic weight of the separator is g / m 2 It is defined as the density × thickness of the separator in units of units.

[0056] In one embodiment, the separator layer comprises a single or multi-layered natural and / or artificial fiber material. Preferably, the average mass / area ratio of the separator layer is 8.0 g / m². 2 It is larger than that.

[0057] In one embodiment, the separator layer includes a filter film layer, and the filter film material may include PET, nylon, PTFE (polytetrafluoroethylene), and / or PES (polyethersulfone). The filter film may contain pores with a diameter larger than 0.22 μm. If the pore size is very large and the film becomes fragile, the separator may include an additional support layer.

[0058] The pores allow for the impregnation of the separator layer with conductive polymers and liquid electrolytes.

[0059] In one embodiment, an intermediate electrolyte layer is placed between the polymer layer and the separator layer. The intermediate electrolyte layer may be provided to increase the breakdown voltage.

[0060] The intermediate electrolyte layer contains an intermediate electrolyte. The intermediate electrolyte may be a conductive viscous material placed between the polymer layer and the separator layer. The intermediate electrolyte may be in contact with the polymer layer. The intermediate electrolyte may be in contact with the separator layer. The intermediate electrolyte may differ from the liquid electrolyte described above in terms of its composition.

[0061] An intermediate electrolyte can prevent the liquid electrolyte from excessively contacting the polymer layer, thereby preventing the liquid electrolyte from damaging, degrading, or causing the polymer layer to swell. Because the intermediate electrolyte is placed between the liquid electrolyte and the polymer layer, it allows for the use of more aggressive materials with superior oxidizing capabilities as the liquid electrolyte. Therefore, the use of an intermediate electrolyte enables the use of materials other than GBL (γ-butyrolactone) and sulfolane solvents as the liquid electrolyte. This, in turn, allows for the construction of capacitors capable of withstanding higher voltages.

[0062] The liquid electrolyte may also be a conductive viscous material. The voltage may be applied to the liquid electrolyte via the cathode foil. The liquid electrolyte may also act as the second electrode of the capacitor.

[0063] The liquid electrolyte and the intermediate electrolyte may have different compositions. For example, the liquid electrolyte may contain ethylene glycol, while the intermediate electrolyte may not contain ethylene glycol. In this case, the intermediate electrolyte without ethylene glycol can ensure that the polymer is not damaged by ethylene glycol. At the same time, the liquid electrolyte containing ethylene glycol can ensure that the advantageous properties of ethylene glycol can be utilized.

[0064] The intermediate electrolyte may contain a polyol and a conductive salt. The conductive salt can ensure that the intermediate electrolyte is conductive.

[0065] In further embodiments, one or more of the carbon layer, titanium layer, titanium oxide layer, and silicon dioxide layer are placed between the cathode layer and the separator layer. Furthermore, the cathode foil can be oxidized. Thus, the cathode foil may have an artificially formed cathode oxide layer. The cathode oxide layer can be thicker than the natural oxide, which has a thickness of 2 nm to 3 nm. These layers protect the cathode metal material and provide further resistance, thus enabling a further improvement in breakdown voltage.

[0066] In one embodiment, several layers between the anode layer and the cathode layer are stacked in the order described above.

[0067] In particular, some layers may be stacked in the following order. Any layer may be omitted. The order of the layers may be anode layer, (unhydrated) oxide layer, hydrated oxide layer, polymer layer, intermediate electrolyte layer, separator layer, and cathode layer. The layers may be in contact with adjacent layers in the above order. Here again, any layer may be omitted.

[0068] In different embodiments, the hybrid polymer capacitor may be either a flat-stacked or wound-type capacitor. [Brief explanation of the drawing]

[0069] The present invention will be described in more detail below with reference to the attached figures. The present invention is not limited to the combination of features or elements shown in the figures and embodiments.

[0070] In the figures, similar or clearly identical elements are marked with the same reference numeral. The figures and their proportions are not scalable. [Figure 1] This is a schematic diagram of a first embodiment of the hybrid polymer capacitor according to the present invention. [Figure 2] This is a TEM partial cross-sectional view of an anode foil having a coated layer. [Figure 3] This figure shows an illustrative test film for measuring the resistance of polymer films. [Figure 4] This is a schematic diagram of a second embodiment of a hybrid polymer capacitor containing a viscous electrolyte layer. [Figure 5] This is a schematic diagram of a third embodiment of a hybrid polymer capacitor containing a carbon layer. [Figure 6] This is a schematic diagram of a third embodiment of a hybrid polymer capacitor containing a titanium layer and a silicon dioxide layer. [Modes for carrying out the invention]

[0071] Figure 1 shows a first embodiment of the hybrid polymer capacitor 100 according to the present invention.

[0072] The overall geometric shape of the capacitor 100 can be designed as either a wound capacitor 100 or a flat-stack capacitor 100. Housings for different types of capacitors 100 with both geometric shapes are possible.

[0073] The hybrid polymer capacitor 100 includes a stack of several layers.

[0074] The capacitor 100 is incorporated into an electrical circuit and includes at least two electrodes, an anode and a cathode, connected to tabs or terminals for external electrical contact. In particular, the anode and cathode electrodes are electrically connected to external positive and negative pins by using lead tabs. The capacitor may be integrated into the electrical circuit, for example, as an electrical filter or as a storage component.

[0075] The anode, in the embodiment shown, includes a metal anode foil 1. The foil preferably includes one anode layer 1 made of aluminum.

[0076] In this example, anode foil 1 is porous in order to increase the surface area of ​​the layer.

[0077] An oxide layer 2 is applied to the surface of the anode foil 1. The oxide layer 2 contains an oxidized anode metal material. In particular, the oxide layer 2 is applied by anodizing the anode metal material. In this embodiment, the oxide layer 2 contains oxidized aluminum, especially alumina (Al2O3).

[0078] The oxide layer 2 preferably has a thickness of 100 nm or more. This minimum thickness of the oxide layer 2 is necessary to provide the minimum allowable breakdown voltage required for the capacitor 100.

[0079] In this example, oxide layer 2 comprises several layers. Oxide layer 2 includes an amorphous Al2O3 layer 2a and a crystalline γ-Al2O3 layer 2b, and the layer thickness ratio (thickness of the crystalline layer / thickness of the amorphous layer) is >0.1. The amorphous layer 2a is coated directly onto the surface of the anode foil 1. The crystalline layer 2b is coated directly onto the opposite side of the amorphous layer 2a.

[0080] The two layers 2a and 2b are also shown in Figure 2. Figure 2 shows a TEM (transmission electron microscopy) partial cross-sectional view of the anode foil 1 coated with layers 2a and 2b.

[0081] The initial leakage current at the anode electrode remains low and stable during the operation of capacitor 100. However, the oxide layer 2 contains isolated voids having diameters in the nanometer range, which are densely distributed on the oxide layer 2. During operation, the isolated voids may condense into larger void structures, reach the surface of the oxide layer 2, and further interact with conductive polymer nanoparticles on the surface of the oxide layer 2, causing a decrease in the breakdown voltage of capacitor 100.

[0082] Therefore, the stability of the oxide layer can be enhanced by a series of chemical or thermal relaxation and improvement processes during manufacturing, which can further reduce the initial leakage current of the capacitor 100 during operation.

[0083] A hydrated oxide layer 3 is applied to the surface of the oxide layer 2 opposite to the anode foil 1. The hydrated oxide layer 3 contains a hydrated anode metal material.

[0084] In this embodiment, the hydrated oxide layer 3 contains hydrated alumina, which is hydrated Al2O3, i.e., Al2O3·xH2O, where x is selected from the range of 0.1 to 3.0.

[0085] The preferred minimum thickness of the oxide layer 2 is 10 nm. The oxide layer 2 and the hydrated oxide layer 3 are formed by coating an aqueous solution of a strong oxidizing electrolyte during the manufacturing process of the capacitor 100.

[0086] The hydrated oxide layer 3 protects the oxide layer 2 as follows.

[0087] Firstly, the hydrated oxide layer 3 is an additional electrical insulating layer to increase the breakdown voltage.

[0088] Secondly, the oxide layer 2 contains natural cracks and voids on the surface of the layer, which are generated, for example, by mechanical or thermal stress. The hydrated oxide layer 3 is a less dense but more homogeneous layer, which prevents, for example, conductive polymer nanoparticles from penetrating the bulk of the oxide layer 2.

[0089] In this way, the hydrated oxide layer 3 prevents the sparking phenomenon in the oxide layer 2 due to its extremely high conductivity.

[0090] Therefore, a sufficient thickness of more than 10 nm of hydrated oxide is required.

[0091] The oxide layer 2 and the hydrated oxide layer 3 are preferably doped with a phosphorus-containing material at least 0.01% atomic percentage to stabilize their structures and avoid the void formation process.

[0092] The polymer layer 4 is deposited on the surface of the hydrated oxide layer 3 opposite to the oxide layer 2 and the anode foil 1. The polymer layer 4 is conductive and contains a conductive polymer, preferably PEDOT:PSS, which means poly(3,4-ethylenedioxythiophene)polystyrene sulfonate, which is a polymer mixture of two ionomers (PEDOT and PSS).

[0093] The polymer is applied by impregnating it with a dispersion of conductive polymer. This allows the conductive polymer nanoparticles to penetrate adjacent layers such as the separator layer 5 and the cathode foil 6, thereby increasing the conductivity of these layers. On the other hand, the hydrated oxide layer 3 prevents the conductive polymer nanoparticles from penetrating the unhydrated oxide layer 2.

[0094] The polymer in polymer layer 4 is homogeneously distributed to improve the electrical performance of capacitor 100, such as capacitance and ESR.

[0095] The liquid working electrolyte of capacitor 100 has a high oxidizing ability for the anode metal, and can penetrate the polymer film and oxide layer 2 to repair oxide defects.

[0096] The conductivity of polymer layer 4 cannot be measured directly. However, film resistance is the inverse of conductivity. Film resistance is the electrical resistance of a polymer layer of a specific thickness over a defined distance. Film resistance can be measured experimentally by applying a current to the polymer test film 200 via a temporary electrode.

[0097] Figure 3 shows an illustrative test film 200. A MYLAR foil 201 measuring 11.5 cm × 21.5 cm was cut and mounted in a sample holder. 2 ml of viscous polymer sample was coated onto the foil. The polymer sample was smoothly dispersed using a hand coater to form polymer film 202.

[0098] Subsequently, the polymer film 202 was dried in an oven at 180°C for 60 minutes. Several silver electrodes 203 were coated onto the polymer film 202 and dried in an oven at 130°C for 20 minutes. The electrodes 203 should be at least 2 cm in length and 2 cm apart from each other.

[0099] As shown in Figure 1, the separator layer 5 is deposited on the surface of the polymer layer 4 opposite to the oxide layer 2 and the anode foil 1.

[0100] The separator layer 5 is placed between the anode and the cathode to avoid direct contact between the electrodes.

[0101] The breakdown phenomenon of capacitor 100 also depends on the characteristics of the separator, such as the type, density, and thickness of the material. More specifically, these characteristics are determined by the separator resistivity, which determines the breakdown voltage. The separator is impregnated with a liquid electrolyte to fill all pores in the separator that the polymer nanoparticles could not reach during impregnation. In this way, the capacitance of capacitor 100 can be maximized.

[0102] The separator layer 5 contains natural and / or artificial fiber material arranged in a single or multi-layer configuration, with an average mass / area ratio of 8.0 g / m². 2It should be higher.

[0103] In this embodiment, the separator includes a filter film layer, and the filter film material may include PET, nylon, PTFE (polytetrafluoroethylene), and / or PES (polyethersulfone). The filter film contains pores with a diameter greater than 0.22 μm. In further embodiments, the separator may include an additional support layer to support a porous and fragile film.

[0104] The separator has a minimum thickness of 50 μm and a density of 0.30 g / cm² to allow for the application of voltages higher than 200 V. 3 It may have a minimum density of . The resulting low efficiency should be higher than 5%, preferably higher than 15%.

[0105] On the side of the separator layer 5 opposite to the polymer layer 4, a metal cathode foil 6 containing a cathode layer 6 is arranged to form the cathode of the capacitor 100. The surface of the cathode foil 6 may have a spongy or grape-like structure and be roughened on the outer surface, and may be stabilized by chemical phosphate treatment and / or by thermal or electrochemical oxidation treatment.

[0106] The liquid electrolyte is impregnated onto the separator and the surfaces of the anode and cathode. The liquid electrolyte has the ability to oxidize the anode metal, particularly aluminum. The conductivity of the liquid electrolyte at 30°C should be at least 200 μS / cm. The water content of the electrolyte should be 0.5% to 5%, preferably 0.5% to 3% (by weight).

[0107] The electrolyte can improve the oxide layer 2, which can therefore withstand voltages exceeding 150V, preferably exceeding 250V, and more preferably at least 400V.

[0108] During the lifespan of capacitor 100, defects may occur on the surface of oxide layer 2. Therefore, a low-conductivity electrolyte is used to repair defects on the surface of oxide layer 2 by oxidation of the anode metal. The high oxidation capacity of the electrolyte relates to a high spark voltage.

[0109] In addition, effective oxidizing capacity is improved by optimizing the water content of the electrolyte, which is a liquid electrolyte.

[0110] The liquid electrolyte has the added advantage of filling the pores in all layers and thus maximizing the capacitance that could be reduced by incomplete contact between the polymer layer 4 and the hydrated or unhydrated oxide layers 2 and 3. Such incomplete contact can lead to a decrease in capacitance during the capacitor's lifetime.

[0111] The breakdown voltage of the capacitor 100 is strongly dependent on the total conductivity between the anode foil 1 and the cathode foil 6.

[0112] Furthermore, the breakdown voltage also depends on the quality of the oxide layer 2 coated on the anode foil 1. In particular, the surface stability of the oxide layer 2 plays an important role. The quality of the oxide layer 2 is influenced by the content of phosphorus-containing substances that stabilize the oxide layer 2 against hydration and sparking phenomena during the lifetime of the capacitor 100.

[0113] In another embodiment shown in Figure 4, the capacitor 100 is fabricated with an additional viscous electrolyte layer 7 between the separator 5 and the polymer layer 4 to increase the breakdown voltage.

[0114] In further embodiments shown in Figures 5 and 6, an additional layer is placed between the cathode foil 6 and the separator layer 5.

[0115] In Figure 5, the carbon layer 8 is coated on the surface of the cathode foil 6.

[0116] In Figure 6, a titanium layer 9, or alternatively a titanium oxide layer 2 and a silicon dioxide layer 10, are placed between the cathode foil 6 and the separator layer 5. These layers 9 and 10 can further increase the breakdown voltage.

[0117] Reference sign 1 anode foil / layer 2. Oxide layer 2a Amorphous oxide layer 2b Crystalline oxide layer 3. Hydrated oxide layer 4 Polymer layer 5 Separator layer 6 Cathode foil 7 Electrolyte layer 8 Carbon layer 9 Titanium layer 10. Silicon dioxide layer 100 Capacitors 200 test films 201 MYLAR Foil 202 Polymer Film 203 Test electrodes

Claims

1. A hybrid polymer capacitor comprising several layers between an anode layer and a cathode layer, comprising a non-hydrated metal oxide layer having a thickness of at least 100 nm in the stacking direction, a hydrated metal oxide layer disposed on the surface of the non-hydrated metal oxide layer, and further comprising a liquid electrolyte having an conductivity of at least 200 μS / cm and a water content of at least 0.5% at 30°C, wherein the hydrated metal oxide layer and the non-hydrated metal oxide layer are impregnated with the liquid electrolyte.

2. The hybrid polymer capacitor according to claim 1, wherein the non-hydrated metal oxide layer is directly coated on the surface of the anode layer.

3. The hybrid polymer capacitor according to claim 1 or 2, wherein the hydrated metal oxide layer has a thickness of at least 10 nm in the stacking direction.

4. The hybrid polymer capacitor according to claim 1 or 2, wherein the hydrated metal oxide layer and / or the unhydrated metal oxide layer comprises a metal oxide, particularly aluminum oxide, alumina.

5. The hybrid polymer capacitor according to claim 1 or 2, wherein the hydrated metal oxide layer and the unhydrated metal oxide layer are doped with phosphate anions.

6. The hybrid polymer capacitor according to claim 1 or 2, wherein the non-hydrated metal oxide layer includes a stack of an amorphous metal oxide layer and a crystalline metal oxide layer.

7. The hybrid polymer capacitor according to claim 1 or 2, wherein a polymer layer containing a conductive polymer is disposed between one or more hydrated metal oxide layers and one or more unhydrated metal oxide layers on one side and the cathode layer on the opposite side.

8. The hybrid polymer capacitor according to claim 7, wherein the polymer layer comprises a PEDOT:PSS polymer material.

9. The hybrid polymer capacitor according to claim 7, wherein a separator layer having a separator resistivity of at least 5% is disposed between the polymer layer and the cathode layer.

10. The hybrid polymer capacitor according to claim 9, wherein the separator resistivity is at least 15%.

11. The hybrid polymer capacitor according to claim 9, wherein the separator layer has a minimum thickness of 50 μm.

12. The density of the separator layer is at least 0.30 g / cm³ ３ The hybrid polymer capacitor according to claim 9.

13. The average mass / area ratio of the separator layer is 8.0 g / m². ２ A hybrid polymer capacitor according to claim 9, which is larger than the above.

14. The hybrid polymer capacitor according to claim 9, wherein the intermediate electrolyte layer is disposed between the polymer layer and the separator layer.

15. The hybrid polymer capacitor according to claim 9, wherein one or more of the carbon layer, titanium layer, titanium oxide layer, and silicon dioxide layer are disposed between the cathode layer and the separator layer.

16. The hybrid polymer capacitor according to claim 1 or 2, wherein the several layers between the anode layer and the cathode layer are stacked in the order described.

17. A hybrid polymer capacitor according to claim 1 or 2, which is a flat-stacked or wound-type capacitor.

18. The hybrid polymer capacitor according to claim 1 or 2, wherein the water content of the liquid electrolyte is 0.5% to 7%.

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