Preparation method of winding core for winding type capacitor and capacitor

Abstract

The invention discloses a preparation method of a winding core for a winding type capacitor, and the method comprises the steps: providing a flexible substrate which is a foil of Ni, Cu, Al or stainless steel, and serves as a bottom electrode; the upper portion of the flexible substrate is coated with a ceramic dielectric layer, the ceramic dielectric layer comprises an amorphous-nanocrystalline material, the crystallinity of the amorphous-nanocrystalline material ranges from 15% to 50%, and the grain size ranges from 5 nm to 40 nm; coating a top electrode layer above the ceramic dielectric layer; and coating an isolation layer above the top electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to a method for preparing a winding core for a wound capacitor and a capacitor. Background Art

[0002] As one of the three major passive components, capacitors have important and widespread applications and are virtually ubiquitous in electronic and electrical devices. Film capacitors use thin film materials as the dielectric. Film capacitor structures can be broadly categorized into two types: wound-type and laminated. Wrap-up film material is wound and stamped, then encased in a housing. Laminated film capacitors consist of multiple layers of film stacked together, then encased in a housing. Due to their ease of manufacture, wound-type film capacitors are currently the most commonly used type.

[0003] Currently, the dielectric material used in wound film capacitors is mostly polymer film. This is because polymer film allows for flexible wound capacitors, significantly increasing capacitance through its structure. However, polymer film suffers from a low dielectric constant, resulting in a low capacitance density. Furthermore, due to inherent limitations of polymer materials, its operating temperature is relatively low.

[0004] Ceramic materials have high dielectric constants and high-temperature resistance, but they are brittle, making it difficult to achieve wound capacitor configurations. Furthermore, existing ceramic dielectric materials have limited capacity, making it difficult to produce high-capacity capacitor materials. While prior art reports have documented the use of ceramic materials as dielectrics for wound capacitors, the impact of ceramic materials on capacitance performance has not been studied, making it impossible to determine the optimal performance of the capacitor. Prior art has not explored how to produce wound capacitors that combine high flexibility, high-temperature resistance, and high capacitance. Summary of the Invention

[0005] The present invention provides a method for preparing a winding core for a wound capacitor and a capacitor, so as to solve the problems of low heat resistance temperature and low capacity of existing wound capacitors.

[0006] In a first aspect, the present invention provides a method for preparing a winding core for a wound capacitor, characterized in that the preparation method comprises:

[0007] S1. Providing a flexible substrate (1), wherein the flexible substrate (1) is a foil of Ni, Cu, Al or stainless steel, and the flexible substrate (1) serves as a bottom electrode;

[0008] S21, preparing a precursor solution;

[0009] S22, precursor solution coating;

[0010] S23, drying and pyrolysis, through steps S21 to S23, coating a ceramic dielectric layer (2) on the flexible substrate; the ceramic dielectric layer comprises an amorphous-nanocrystalline material, the amorphous-nanocrystalline material has a crystallinity of 15 to 50% and a grain size of 5 to 40 nm;

[0011] S3, coating a top electrode layer (3) above the ceramic dielectric layer, and;

[0012] S4. Coating an insulating layer (4) above the top electrode.

[0013] The wound capacitors in the prior art mostly use polymer materials as the dielectric layer. Although polymer materials have good flexibility, their dielectric constant is low and their heat resistance temperature is low. Therefore, their application is limited for high-capacity, high-temperature resistant capacitors. The ceramic dielectric layer obtained by the chemical deposition method of the present invention contains amorphous-nanocrystalline materials, and ceramic dielectric materials are used as the dielectric layer. The crystallinity of the amorphous-nanocrystalline materials is 15-50%, and the grain size is 5-40nm. By using the above-mentioned amorphous-nanocrystalline materials and controlling their crystallization properties, it is possible to achieve higher heat resistance and dielectric constant while improving the overall flexibility, thereby improving the performance of the wound capacitor and expanding its scope of use.

[0014] In an optional embodiment, the preparation of the precursor solution specifically includes:

[0015] Dissolve one or more of lanthanum nitrate, lead acetate, zirconium n-propoxide, tetrabutyl titanate, barium nitrate, bismuth acetate, and ferric nitrate in a solvent. Sodium acetate may also be added. Heat in a solvent at 60-150°C for 0.5-3 hours. Subsequently, the resulting mixture is continuously stirred under ambient conditions for 1-3 hours to ensure complete dissolution, thereby obtaining a clear and transparent dielectric precursor solution. The concentration of the precursor solution is 0.1-0.4M. The solvent used is one or more of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid.

[0016] In an optional embodiment, the precursor solution coating specifically includes:

[0017] The precursor solution obtained above is deposited on a flexible substrate. Specifically, a process such as spin coating, spray coating, brushing, or dipping can be used. Taking the spin coating process as an example, the spin coating speed is 3000-6000 rpm and the duration is 10-60 seconds. The spin coating can be repeated several times according to the coating requirements.

[0018] In an optional embodiment, the drying and pyrolysis specifically includes:

[0019] The wet film obtained by S2 deposition is baked at 100-300°C for 0.5-5 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 350-500°C for 0.5-5 minutes to eliminate residual organic matter. The film is finally crystallized at a temperature of 250-750°C for 1-20 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, which improves the flexibility of the ceramic and ensures that it will not be damaged or cracked when wound. In this way, a ceramic dielectric layer deposited on the substrate can be obtained.

[0020] Through research, the applicant discovered that by improving the chemical deposition process, the crystallization properties of the deposited film can be adjusted to obtain an amorphous-nanocrystalline material with a crystallinity of 15-50% and a grain size of 5-40 nm. Furthermore, through testing, it was found that the capacitor core prepared from the amorphous-nanocrystalline material with the above crystallinity and grain size can achieve higher heat resistance and dielectric constant while improving overall flexibility.

[0021] In an optional embodiment, the ceramic dielectric layer is an oxide of one or more of La, Pb, Zr, Ti, Ba, Bi, and Fe.

[0022] In an optional embodiment, the ceramic dielectric layer further includes Na oxide.

[0023] In an optional embodiment, the top electrode layer is formed by evaporation, sputtering or spraying.

[0024] In an optional embodiment, the insulating layer is paper or polymer material.

[0025] In an optional embodiment, the thickness of the flexible substrate is 10-100 μm, and the thickness of the ceramic dielectric layer is 50-1000 nm.

[0026] In an optional embodiment, the core further includes a protective layer located above the dielectric layer, the protective layer has a thickness of 5 to 50 nm, and the protective layer is PbO, Bi2O3, or K2O.

[0027] In an optional embodiment, the dielectric constant of the ceramic dielectric layer is 40-800.

[0028] In an optional embodiment, the maximum strain e of the winding core is greater than 1%, and the maximum strain e is calculated as follows:

[0029]

[0030] Where t is the core thickness and r is the winding radius.

[0031] In an optional embodiment, step S5 is further included, wherein two or more layers of winding cores are stacked and a final winding core is obtained through a winding process.

[0032] The capacitor core prepared by the above method has a ceramic dielectric layer comprising an amorphous-nanocrystalline material with a crystallinity of 15-50% and a grain size of 5-40 nm. The inventors, through experimental comparison, found that by controlling the crystallinity of the amorphous-nanocrystalline material in the ceramic dielectric layer to 15-50% and a grain size of 5-40 nm, not only can the overall flexibility of the core be improved, but also higher heat resistance and dielectric constant can be achieved, thus resolving the low capacitance and poor heat resistance issues of existing wound capacitors.

[0033] In a second aspect, the present invention provides a capacitor comprising a capacitor core prepared by the above method.

[0034] a conductive component, the conductive component comprising a first tab connected to an inner electrode of the wound component and a second tab connected to an outer electrode of the wound component;

[0035] and a packaging component in which the wound component is completely housed.

[0036] In an optional embodiment, the packaging assembly includes a shell for accommodating the winding assembly, and a sealing structure at one end for sealing.

[0037] In an optional embodiment, the operating temperature range of the capacitor is -80 to 150°C.

[0038] For the technical effects that may be achieved by the capacitor disclosed in the second aspect, please refer to the above description of the technical effects that may be achieved by the first aspect or various possible solutions in the first aspect, and no further details will be given here.

[0039] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 A schematic diagram of a winding core according to one embodiment of the present invention;

[0042] Figure 2A schematic diagram of a winding core according to one embodiment of the present invention;

[0043] Figure 3 A schematic diagram of a winding core according to one embodiment of the present invention;

[0044] Names in the accompanying drawings:

[0045] 1-Flexible substrate, 2-Ceramic dielectric layer, 3-Top electrode, 4-Isolation layer, 5-Protective layer. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0047] As mentioned earlier, the dielectric material currently used in wound film capacitors is mostly polymer film. This is because polymer film allows for flexible wound capacitors, significantly increasing capacitance through its structure. However, it suffers from the disadvantage of a low dielectric constant. Furthermore, due to inherent limitations of polymer materials, its operating temperature is relatively low.

[0048] Ceramic materials have high dielectric constants and high-temperature resistance, but their brittleness makes them difficult to achieve in wound capacitor configurations. Furthermore, existing ceramic dielectric materials have limited capacity, making it difficult to produce high-capacity capacitor materials. While prior art reports have documented the use of ceramic materials as dielectrics for wound capacitors, no research has been conducted on how to create wound capacitors that combine high flexibility, high-temperature resistance, and high capacitance. Furthermore, no research has been conducted on the impact of ceramic materials on capacitor performance, making it difficult to determine the optimal performance of the capacitor.

[0049] Therefore, the present invention aims to provide a method for preparing a winding core for a wound capacitor and a capacitor.

[0050] Based on this, an embodiment of the present invention provides a method for preparing a winding core for a wound capacitor, the method comprising:

[0051] S1. Providing a flexible substrate, wherein the flexible substrate is a foil of Ni, Cu, Al or stainless steel, and the flexible substrate serves as a bottom electrode;

[0052] S21, preparing a precursor solution;

[0053] S22, precursor solution coating;

[0054] S23, drying and pyrolysis, through steps S21 to S23, coating a ceramic dielectric layer on the flexible substrate; the ceramic dielectric layer comprises an amorphous-nanocrystalline material, the amorphous-nanocrystalline material has a crystallinity of 15-50% and a grain size of 5-40 nm;

[0055] S3, coating a top electrode layer on top of the ceramic dielectric layer, and;

[0056] S4. Coating an insulating layer on the top electrode.

[0057] The ceramic dielectric layer prepared by the chemical deposition method of the present invention comprises an amorphous-nanocrystalline material. The ceramic dielectric material used as the dielectric layer has a crystallinity of 15-50% and a grain size of 5-40nm. Through experimental comparison, the inventors found that by controlling the crystallinity of the amorphous-nanocrystalline material in the ceramic dielectric layer to 15-50% and the grain size to 5-40nm, not only can the overall flexibility of the winding core be improved, but also higher heat resistance and dielectric constant can be achieved, solving the problems of low capacitance and poor heat resistance in prior art wound capacitors.

[0058] To better understand the technical solutions provided by the embodiments of the present invention, the following briefly introduces the application scenarios to which the technical solutions provided by the embodiments of the present invention are applicable. It should be noted that the application scenarios described below are only for the purpose of illustrating the embodiments of the present invention and are not intended to limit the scope of the present invention. During specific implementation, the technical solutions provided by the embodiments of the present invention can be flexibly applied according to actual needs.

[0059] like Figure 1 As shown, the winding core used for the wound capacitor in this embodiment includes a flexible substrate 1, and the flexible substrate is used as the bottom electrode. In addition, it also includes a ceramic dielectric layer 2 located on the flexible substrate layer, and the ceramic dielectric layer contains amorphous-nanocrystalline material. Through experiments, it was found that when the crystallinity of the amorphous-nanocrystalline material is 15-50% and the grain size is 5-40nm, the overall flexibility of the winding core can be guaranteed, and the heat resistance and dielectric constant of the winding core can be improved. In addition, the winding core also includes a top electrode layer 3 located on the ceramic dielectric layer, and an insulating layer 4 located on the top electrode layer. The thickness of the flexible substrate 1 is 10-100μm, and the thickness of the ceramic dielectric layer 2 is 50-1000nm.

[0060] Specifically, the ceramic dielectric layer 2 comprises one or more oxides of La, Pb, Zr, Ti, Ba, Bi, and Fe. These metal oxides can be used as ceramic dielectric layer materials. These metal oxides include single oxides of these elements, mixtures of these oxides, and co-oxides of these elements. In an optional embodiment, Na oxides can also be added, or Na can be co-oxides formed with these elements to form the ceramic dielectric layer 2.

[0061] Ceramic electrolytes can be prepared by chemical deposition process. Specifically, they can be prepared by the following steps:

[0062] S1, prepare precursor solution.

[0063] Dissolve one or more of lanthanum nitrate, lead acetate, zirconium n-propoxide, tetrabutyl titanate, barium nitrate, bismuth acetate, and ferric nitrate in a solvent. Sodium acetate may also be added. Heat in a solvent at 60-150°C for 0.5-3 hours. Subsequently, the resulting mixture is continuously stirred under ambient conditions for 1-3 hours to ensure complete dissolution, thereby obtaining a clear and transparent dielectric precursor solution. The concentration of the precursor solution is 0.1-0.4M. The solvent used is one or more of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid.

[0064] S2, precursor solution coating.

[0065] The precursor solution obtained above is deposited on a flexible substrate. Specifically, a process such as spin coating, spray coating, brushing, or dipping can be used. Taking the spin coating process as an example, the spin coating speed is 3000-6000 rpm and the duration is 10-60 seconds. The spin coating can be repeated several times according to the coating requirements.

[0066] S3, drying and pyrolysis.

[0067] The wet film obtained by S2 deposition is baked at 100-300°C for 0.5-5 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 350-500°C for 0.5-5 minutes to eliminate residual organic matter. The film is finally crystallized at a temperature of 250-750°C for 1-20 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, which improves the flexibility of the ceramic and ensures that it will not be damaged or cracked when wound. In this way, a ceramic dielectric layer deposited on the substrate can be obtained.

[0068] In addition, the ceramic dielectric layer may be obtained by deposition methods other than the above-mentioned deposition methods, such as vacuum evaporation, magnetron sputtering, ion beam sputtering, ion plating, molecular beam epitaxy, chemical vapor deposition, and physical vapor deposition.

[0069] The flexible substrate material can be a foil of Ni, Cu, Al, or stainless steel. These metal foils offer excellent flexibility and winding properties, allowing them to maintain good performance even with large winding curvatures. Furthermore, these metal foils offer excellent electrical conductivity and can be used directly as the bottom electrode, eliminating the need for a separate bottom electrode layer. This simplifies the manufacturing process, reduces costs, and improves the capacitor's performance stability.

[0070] Flexible substrates are not limited to the foils of the above-mentioned metal materials. In addition to the above, mica sheets pre-plated with oxide electrodes or metal electrodes can also be used as flexible substrate materials. Mica sheets have good flexibility and are suitable for use as substrates. In order to ensure the use of capacitors, an electrode layer must be pre-plated on the mica sheet. The electrode layer can be single-sided metallized, double-sided metallized, or a series-type bimetallized structure. The electrode layer can be an oxide electrode or a metal electrode. When using an oxide electrode, LaNiO3 or SrRuO3 materials can be selected. When using a metal electrode, metal materials such as Ag, Ni or Cu can be selected. Of course, it is not limited to the oxide electrodes or metal electrodes mentioned above. Any oxide or conductive metal with an electrode function can be regarded as an equivalent alternative to this solution.

[0071] The top electrode is made of commonly used electrode materials in the prior art, such as the aforementioned Ag, Ni, or Cu. Pt or Au can also be used as the top electrode material. The top electrode material can be prepared by evaporation, sputtering, or spraying. The specific process details can be referred to the existing technology and will not be described in detail in this technology. The above-mentioned bottom electrode layer and top electrode layer can be connected to the first and second contacts of the capacitor via the inner electrode and outer electrode, respectively, to form the two electrode interfaces of the capacitor.

[0072] In addition, to prevent the bottom electrode from contacting the top electrode after winding, the top electrode layer 3 is covered with an insulating layer 4. The insulating layer 4 is made of a material with good insulation performance and easy to wind, such as paper or polymer material.

[0073] like Figure 2 As shown, the winding core also includes a protective layer 5 located above the dielectric layer 2. Because the dielectric layer contains elements such as Pb and Bi, they may volatilize after prolonged use. Therefore, to improve the performance of the capacitor, a protective layer 5 can be added above the dielectric layer 2. The protective layer 5 can be made of materials such as PbO, Bi2O3, or K2O, and its thickness can be 5 to 50 nm. The protective layer 5 can be prepared by evaporation, sputtering, or spraying.

[0074] By partially crystallizing the ceramic dielectric layer and controlling the crystallinity and grain size, better heat resistance and higher flexibility can be achieved. In addition, the dielectric constant of the dielectric layer is 40 to 800. Regarding the flexibility of the core, this technology uses the maximum strain e of the core to characterize it. The specific test method is: the core is wound with the smallest possible curvature radius, and the maximum strain is calculated based on the thickness t of the core and the winding radius r. The maximum strain e can be obtained, that is:

[0075]

[0076] The maximum strain e of the winding core obtained according to the present invention should be greater than 1%.

[0077] like Figure 3 As shown, the winding core of the present invention can be a multi-layer winding core formed by stacking multiple layers of winding cores and then winding them. By stacking multiple layers, the capacity of the capacitor can be further increased.

[0078] The present technology also provides a capacitor, which includes the above-mentioned winding core wound to form a winding component, and the winding component includes an inner electrode and an outer electrode, and the inner electrode and the outer electrode are respectively connected to the bottom electrode and the top electrode.

[0079] The capacitor further includes a conductive member comprising a first tab connected to the inner electrode of the jellyroll and a second tab connected to the outer electrode of the jellyroll.

[0080] The capacitor also includes an encapsulation component for housing the wound component, which is completely contained within the encapsulation component. The encapsulation assembly includes a housing for housing the wound component and a sealing structure at one end for sealing. The capacitor's conductive component passes through the sealing structure, with one end connected to the interior of the capacitor and the other end extending outward from the capacitor.

[0081] The capacitor prepared by using the winding core has an operating temperature range of -80 to 150°C.

[0082] After introducing the application scenarios of the embodiments of the present invention, the preferred implementation methods of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

[0083] In addition, although the embodiments of the present invention provide method operation steps as shown in the following embodiments or drawings, more or less operation steps may be included in the method based on routine or without creative labor. In the steps where there is no necessary causal relationship logically, the execution order of these steps is not limited to the endpoints of the scope disclosed in this article and any value is not limited to the precise range or value, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, between the endpoint values ​​of each range, between the endpoint values ​​of each range and a separate point value, and between the separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered to be specifically disclosed in this article.

[0084] Based on the process described above, seven representative examples are selected below and their related performances are tested.

[0085] Example 1:

[0086] Metal Au is selected as a flexible substrate, which is used as the bottom electrode. The thickness of the substrate is 50 μm. The ceramic dielectric layer is prepared by chemical deposition process:

[0087] S1, prepare precursor solution.

[0088] Lanthanum nitrate and lead acetate were dissolved in a mixture of ethylene glycol and acetic acid and heated at 250°C for 0.5 hours. The resulting mixture was then stirred at ambient conditions for 2 hours to ensure complete dissolution, resulting in a clear and transparent dielectric precursor solution. The concentration of the precursor solution was 0.2M.

[0089] S2, precursor solution coating.

[0090] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 3000 rpm and the duration is 20 seconds.

[0091] S3, drying and pyrolysis.

[0092] The wet film obtained by S2 deposition was baked at 150°C for 2 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 400°C for 3 minutes to eliminate residual organic matter. The film was finally crystallized at 650°C for 3 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0093] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0094] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0095] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0096] Example 2:

[0097] Metal Cu was selected as a flexible substrate, which served as the bottom electrode. The thickness of the substrate was 50 μm. The ceramic dielectric layer was prepared by chemical deposition process:

[0098] S1, prepare precursor solution.

[0099] Zirconium n-propoxide and tetrabutyl titanate were dissolved in a mixture of ethylene glycol and acetic acid. The mixture was heated at 100°C for 2 hours. The resulting mixture was then stirred at ambient conditions for 3 hours to ensure complete dissolution, resulting in a clear and transparent dielectric precursor solution. The concentration of the precursor solution was 0.25M.

[0100] S2, precursor solution coating.

[0101] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 4000 rpm and the duration is 30 seconds.

[0102] S3, drying and pyrolysis.

[0103] The wet film obtained by S2 deposition was baked at 200°C for 2 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 450°C for 5 minutes to eliminate residual organic matter. The film was finally crystallized at 500°C for 8 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0104] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0105] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0106] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0107] Example 3:

[0108] Metal Al was selected as a flexible substrate, which served as the bottom electrode. The thickness of the substrate was 50 μm. A ceramic dielectric layer was prepared by chemical deposition process:

[0109] S1, prepare precursor solution.

[0110] Barium nitrate, bismuth acetate, and ferric nitrate were dissolved in a mixture of ethylene glycol and acetic acid. The mixture was heated at 150°C for 2 hours. The resulting mixture was then stirred at ambient conditions for 1 hour to ensure complete dissolution, resulting in a clear and transparent dielectric precursor solution. The concentration of the precursor solution was 0.3 M.

[0111] S2, precursor solution coating.

[0112] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 5000 rpm and the duration is 20 seconds.

[0113] S3, drying and pyrolysis.

[0114] The wet film obtained by S2 deposition was baked at 180°C for 4 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 400°C for 4 minutes to eliminate residual organic matter. The film was finally crystallized at 500°C for 20 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0115] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0116] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0117] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0118] Example 4:

[0119] Metal Ni is selected as a flexible substrate, which is used as the bottom electrode. The thickness of the substrate is 50 μm. The ceramic dielectric layer is prepared by chemical deposition process:

[0120] S1, prepare precursor solution.

[0121] Zirconium n-propoxide, tetrabutyl titanate, bismuth acetate, and sodium acetate were dissolved in a mixed solvent of ethylene glycol and acetic acid. The mixture was heated at 150°C for 0.5 hours. The resulting mixture was then stirred at ambient conditions for 1.5 hours to ensure complete dissolution, resulting in a clear, transparent dielectric precursor solution. The concentration of the precursor solution was 0.15 M.

[0122] S2, precursor solution coating.

[0123] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 4500 rpm and the duration is 20 seconds.

[0124] S3, drying and pyrolysis.

[0125] The wet film obtained by S2 deposition was baked at 150°C for 5 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 400°C for 1 minute to eliminate residual organic matter. The film was finally crystallized at 650°C for 30 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0126] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0127] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0128] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0129] Example 5:

[0130] Metal Cu was selected as a flexible substrate, which served as the bottom electrode. The thickness of the substrate was 50 μm. The ceramic dielectric layer was prepared by chemical deposition process:

[0131] S1, prepare precursor solution.

[0132] Lanthanum nitrate and lead acetate were dissolved in a mixture of ethylene glycol and acetic acid and heated at 250°C for one hour. The resulting mixture was then stirred at ambient conditions for two hours to ensure complete dissolution, resulting in a clear, transparent dielectric precursor solution. The concentration of the precursor solution was 0.05M.

[0133] S2, precursor solution coating.

[0134] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 3000 rpm and the duration is 20 seconds.

[0135] S3, drying and pyrolysis.

[0136] The wet film obtained by S2 deposition was baked at 100°C for 1 minute to promote the evaporation of the organic solvent, and then pyrolyzed at 250°C for 1 minute to eliminate residual organic matter. The film was finally crystallized at 180°C for 2 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0137] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0138] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0139] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0140] Example 6:

[0141] Metal Ni is selected as a flexible substrate, which is used as the bottom electrode. The thickness of the substrate is 50 μm. The ceramic dielectric layer is prepared by chemical deposition process:

[0142] S1, prepare precursor solution.

[0143] Lanthanum nitrate and lead acetate were dissolved in a mixture of ethylene glycol and acetic acid and heated at 250°C for 0.5 hours. The resulting mixture was then stirred at ambient conditions for 2 hours to ensure complete dissolution, resulting in a clear and transparent dielectric precursor solution. The concentration of the precursor solution was 0.2M.

[0144] S2, precursor solution coating.

[0145] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 4000 rpm and the duration is 20 seconds.

[0146] S3, drying and pyrolysis.

[0147] The wet film obtained by S2 deposition was baked at 150°C for 2 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 400°C for 3 minutes to eliminate residual organic matter. The film was finally crystallized at 150°C for 10 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0148] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0149] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0150] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0151] Example 7:

[0152] Metal Ni was selected as a flexible substrate, which served as the bottom electrode. The thickness of the substrate was 50 μm. It was prepared by chemical deposition process:

[0153] Metal Ni is selected as a flexible substrate, which is used as the bottom electrode. The thickness of the substrate is 50 μm. The ceramic dielectric layer is prepared by chemical deposition process:

[0154] S1, prepare precursor solution.

[0155] Lanthanum nitrate and lead acetate were dissolved in a mixture of ethylene glycol and acetic acid and heated at 200°C for one hour. The resulting mixture was then stirred at ambient conditions for two hours to ensure complete dissolution, resulting in a clear, transparent dielectric precursor solution. The concentration of the precursor solution was 0.6 M.

[0156] S2, precursor solution coating.

[0157] The precursor solution obtained above is deposited on a flexible substrate, specifically, by spin coating, spray coating, brushing, dipping, etc. Taking the spin coating process as an example, the spin coating speed is 4000 rpm and the duration is 30 seconds.

[0158] S3, drying and pyrolysis.

[0159] The wet film obtained by S2 deposition was baked at 300°C for 4 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 500°C for 5 minutes to eliminate residual organic matter. The film was finally crystallized at 800°C for 30 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, thus obtaining a ceramic dielectric layer deposited on the substrate.

[0160] A layer of Ag is plated on the ceramic dielectric layer as a top electrode layer. The thickness of the top electrode layer is 100 μm.

[0161] Finally, a paper insulating layer was applied to the top electrode layer to obtain a core material. The maximum strain e and dielectric constant ε of the core material were tested.

[0162] The next step is to prepare the above-mentioned core into capacitor material. The 30cm long and 2cm wide core material is wound using the existing conventional winding method to form a wound component containing an inner electrode and an outer electrode, and the inner electrode and the outer electrode are connected to the bottom electrode and the top electrode respectively. The first tab and the second tab are connected to the bottom electrode and the top electrode respectively. Finally, the obtained component is packaged in a packaging component, wherein the wound component is placed in the outer shell of the packaging component, and the outer shell is sealed with a sealing structure to obtain the final capacitor product. The temperature range T of the capacitor and the capacitor capacitance C are tested.

[0163] The performance of the winding core provided in the embodiments of the present invention and the capacitors prepared from the winding core are tested below. Specifically, the tested performance includes: the maximum strain e of the winding core, where this parameter can be bent using a fixture and the bending curvature obtained by imaging; and the dielectric constant ε of the winding core, which can be obtained by testing with an LCR meter at 1kHz and calculating. It should be familiar to those skilled in the art.

[0164] Also, the operating temperature range T of the capacitor, which can be obtained by testing with an external LCR meter in an environmental test chamber; and the capacitor capacitance C, which can be obtained by testing with an LCR meter at 1kHz.

[0165] By testing 7 sets of cores and the corresponding capacitor performance, the results are as follows:

[0166]

[0167]

[0168] According to the above results, this technology can improve the overall flexibility of the winding core by controlling the crystallinity and grain size of the ceramic dielectric layer, and can also achieve higher heat resistance and dielectric constant, thereby solving the problems of low capacity and poor heat resistance of wound capacitors in the existing technology and expanding the operating range of wound capacitors.

[0169] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0170] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a winding core for a wound capacitor, characterized in that: The preparation method comprises: S1. Providing a flexible substrate (1), wherein the flexible substrate (1) is a foil of Ni, Cu, Al or stainless steel, and the flexible substrate (1) serves as a bottom electrode; S21, preparing a precursor solution; S22, precursor solution coating; S23, drying and pyrolysis, through steps S21 to S23, coating a ceramic dielectric layer (2) on the flexible substrate; the ceramic dielectric layer comprises an amorphous-nanocrystalline material, the amorphous-nanocrystalline material has a crystallinity of 15 to 50% and a grain size of 5 to 40 nm; S3, coating a top electrode layer (3) above the ceramic dielectric layer, and; S4. Coating an insulating layer (4) above the top electrode.

2. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The preparation of the precursor solution specifically includes: Dissolve one or more of lanthanum nitrate, lead acetate, zirconium n-propoxide, tetrabutyl titanate, barium nitrate, bismuth acetate, and ferric nitrate in a solvent. Sodium acetate may also be added. Heat in a solvent at 60-150°C for 0.5-3 hours. Subsequently, the resulting mixture is continuously stirred under ambient conditions for 1-3 hours to ensure complete dissolution, thereby obtaining a clear and transparent dielectric precursor solution. The concentration of the precursor solution is 0.1-0.4M. The solvent used is one or more of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid.

3. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The precursor solution coating specifically includes: The precursor solution obtained above is deposited on a flexible substrate. Specifically, a process such as spin coating, spray coating, brushing, or dipping can be used. Taking the spin coating process as an example, the spin coating speed is 3000-6000 rpm and the duration is 10-60 seconds. The spin coating can be repeated several times according to the coating requirements.

4. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The drying pyrolysis specifically comprises: The wet film obtained by S2 deposition is baked at 100-300°C for 0.5-5 minutes to promote the evaporation of the organic solvent, and then pyrolyzed at 350-500°C for 0.5-5 minutes to eliminate residual organic matter. The film is finally crystallized at a temperature of 250-750°C for 1-20 minutes to ensure partial crystallization and form an amorphous-nanocrystalline composite, which improves the flexibility of the ceramic and ensures that it will not be damaged or cracked when wound. In this way, a ceramic dielectric layer deposited on the substrate can be obtained.

5. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The ceramic dielectric layer (2) is one or more oxides of La, Pb, Zr, Ti, Ba, Bi, and Fe.

6. The method for preparing a winding core for a wound capacitor according to claim 5, wherein: The ceramic dielectric layer (2) further comprises Na oxide.

7. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The top electrode layer (3) is formed by evaporation, sputtering or spraying process.

8. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The insulating layer (4) is made of paper or polymer material.

9. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The thickness of the flexible substrate (1) is 10 to 100 μm, and the thickness of the ceramic dielectric layer (2) is 50 to 1000 nm.

10. The method for preparing a winding core for a wound capacitor according to claim 9, wherein: The winding core further comprises a protective layer (5) located above the dielectric layer (2), the thickness of the protective layer (5) is 5 to 50 nm, and the protective layer (5) is PbO, Bi2O3 or K2O.

11. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The dielectric constant of the ceramic dielectric layer is 40-800.

12. The method for preparing a winding core for a wound capacitor according to claim 1, wherein: The maximum strain e of the winding core is greater than 1%, and the maximum strain e is calculated as follows: Where t is the core thickness and r is the winding radius.

13. The method for preparing a winding core for a wound capacitor according to any one of claims 1 to 12, characterized in that: The method further includes step S5 of stacking two or more layers of winding cores and obtaining a final winding core through a winding process.

14. A capacitor, characterized in that: The capacitor comprises a winding core obtained according to claim 13 .

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