Internal series type multilayer ceramic capacitor

Abstract

The invention relates to the technical field of energy storage, in particular to an internal serial multilayer ceramic capacitor. The invention relates to an internal serial multilayer ceramic capacitor, which comprises a ceramic dielectric layer, an inner electrode and a terminal electrode, the inner electrodes and the ceramic dielectric layers are alternately stacked; the end electrodes are located on the two sides perpendicular to the stacking direction and connected with the inner electrodes through the ceramic dielectric layers, and the ceramic dielectric layers are arranged on the two sides, parallel to the stacking direction, of the capacitor. The multilayer ceramic capacitor is simple in preparation process, high in operability and relatively low in total cost; the serial number of elements can be greatly reduced, and the welding workload is reduced; and by combining with a rare earth ion doped lead-based anti-ferroelectric material, the internal serial multilayer ceramic capacitor is prepared, can be used for an energy storage capacitor, and has a good application prospect in a pulse power system.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to an internal series type multilayer ceramic capacitor. Background Art

[0002] The booming economy has led to a continuous increase in demand for renewable energy such as solar energy, wind energy, and thermal energy, prompting the research and development of new energy storage devices to become a scientific research focus. As electronic products are increasingly moving towards miniaturization and high integration, capacitors are facing technical bottlenecks in the transition to ultra-micro size, ultra-large capacity, and ultra-thin form, which sets more stringent standards for the dielectric breakdown strength, energy storage efficiency, and energy storage density of capacitors. In this context, ceramic-based dielectric energy storage capacitors, with their excellent ultra-high power density characteristics, have shown extensive application potential in many fields such as hybrid systems and pulse medical technology. However, the current capacitor electrode structure on the market generally adopts a two-end lead design, and the internal electrode structure is relatively simple. Although the introduction of conductive plates as connecting wires can reduce the internal inductance of the capacitor to a certain extent, this method is limited in energy storage density due to the large number of conductive plates required and the complicated welding process. In addition, this structure is prone to induce a large circular current inside the capacitor, which has no substantial help in improving the breakdown field strength, and thus it is difficult to effectively reduce the inductance. What’s worse, as the capacitor capacity increases and its height rises, the breakdown electric field strength decreases, directly shortening its service life.

[0003] Chinese invention patent CN110867321B, March 6, 2020, discloses a multilayer ceramic capacitor, including an effective electrode layer and a reinforcement, wherein the reinforcement is arranged at least one of the upper surface of the effective electrode layer, the inside of the effective electrode layer, and the lower surface of the effective electrode layer; the two end faces of the effective electrode layer and the reinforcement are in contact with the end electrode; by arranging a high-strength material layer evenly distributed in the ceramic dielectric layer of the MLCC through the multilayer ceramic capacitor, the flexural strength and bending strength of the MLCC are greatly improved while ensuring the original electrical properties of the capacitor, and the internal electrode structure is relatively simple and does not involve an internal series structure. Summary of the invention

[0004] The present invention provides an inner series type multilayer ceramic capacitor, comprising: a ceramic dielectric layer, an inner electrode and an end electrode; the inner electrode and the ceramic dielectric layer are alternately stacked; the end electrode is located on both sides perpendicular to the stacking direction and connected to the inner electrode through the ceramic dielectric layer, wherein the ceramic dielectric layer is arranged on both sides of the capacitor parallel to the stacking direction; The overlapping portion of the internal electrode A and the internal electrode B perpendicular to the stacking direction is circular or elliptical.

[0005] The number of the inner electrodes A arranged in the same layer is 2-4.

[0006] The spacing between the inner electrodes A in the same layer is c, and 0.5 mm≤c≤3 mm.

[0007] The length and width of the ceramic dielectric layer are W and Y respectively, and the thickness is t; the inner electrode includes an inner electrode A and an inner electrode B, the length and width of the inner electrode A are d and h respectively, and the length and width of the inner electrode B are b and h respectively; the width of the pore between the inner electrode A and the end electrode is a; wherein, 10 mm≤W≤60 mm, 10 mm≤Y≤60 mm, 1 mm≤d≤5 mm, 2mm≤b≤10 mm, 0.4 mm≤h≤4 mm, and 8 mm≤t≤25 mm.

[0008] Optional, 10 mm≤W≤40 mm, 10 mm≤Y≤30 mm, 1 mm≤d≤3 mm, 2 mm≤b≤5mm, 0.4mm≤h≤2 mm, 15mm≤t≤25 mm, 0.5 mm≤c≤1.5 mm.

[0009] The layers of the multilayer ceramic capacitor are alternately stacked according to the internal electrodes A, the ceramic dielectric layers, the internal electrodes B, and the ceramic dielectric layers.

[0010] The inner electrode is a Pt electrode, a silver-palladium electrode or a copper electrode, and the terminal electrode is a silver electrode.

[0011] The width of the gap between the inner electrode A and the end electrode is a, 0.5 mm≤a≤2 mm.

[0012] Optionally, the number of the inner electrodes A arranged in the same layer is 2.

[0013] Optionally, the inner electrode A includes a shoe-shaped electrode, and the inner electrode B includes an elliptical electrode.

[0014] The raw materials for preparing the ceramic dielectric layer include rare earth ion-doped lead-based antiferroelectric materials, the chemical formula of which is Pb (1.01 - 1.5z-y) M z Ca y (Zr 1-x Sn x ) 0.995 O 3 , wherein M includes any one or more of the rare earth elements La, Sm, Nd, Eu, Gd, Pr, Dy and Yb, 0.008≤z≤0.05, 0.01≤y≤0.05, 0.1≤x≤0.5.

[0015] Optional, 0.008≤z≤0.03, 0.01≤y≤0.03, 0.2≤x≤0.4.

[0016] The dielectric layer is a rare earth ion doped lead-based antiferroelectric material system, and the chemical formula is Pb (1.01-1.5z-y) M z Ca y (Zr 1-x Sn x ) 0.995 O 3 , M includes any one or more of the rare earth elements La, Sm, Nd, Eu, Gd, Pr, Dy and Yb, and the subscript numbers in the general formula represent the molar ratio of the elements. 3 The structure is perovskite structure, Pb 2+ Located at the corner of oxygen octahedron, O 2- Exists at the oxygen octahedral face center, Zr 4+ and Sn 4+ The antiferroelectric ceramic material contains Pb in the A-site. 2+ In addition, one or more elements are selected from the components consisting of Ca, La, Sm, Nd, Eu, Gd, Pr, Dy and Yb to construct antiferroelectric ceramics, which can enhance the field-induced antiferroelectric-ferroelectric phase transition electric field and reduce hysteresis loss. 2+ The radius is closer, and the above rare earth ions simultaneously replace Pb at the A position 2+ , which can achieve the synchronous enhancement of the field-induced phase change electric field and the breakdown electric field, and further improve the Pb(Zr,Sn)O 3 Energy storage performance of thick film materials.

[0017] The raw materials for preparing the ceramic dielectric layer also include solvent, plasticizer, dispersant, binder and homogenizer.

[0018] Optionally, based on the weight percentage of the rare earth ion-doped lead-based antiferroelectric material, the raw materials for preparing the ceramic dielectric layer also include 50-70wt% of a solvent, 8-15wt% of a plasticizer, 0.1-2wt% of a dispersant, 5-10wt% of a binder, and 1-5wt% of a homogenizer.

[0019] The solvent includes a benzene solvent and an alcohol solvent.

[0020] Optionally, the weight ratio of the benzene solvent to the alcohol solvent is 1:(0.8-1.2).

[0021] The dispersant comprises a phosphate ester, preferably tributyl phosphate.

[0022] The binder is not limited, but is preferably polyvinyl butyral.

[0023] The plasticizer comprises polyethylene glycol, tributyl phthalate and cyclohexanone, and the weight ratio of the polyethylene glycol, tributyl phthalate and cyclohexanone is 1:(0.8-1.5):(1-1.5).

[0024] The method for preparing the inner series type multilayer ceramic capacitor comprises the following steps: S1, pre-treating a rare earth ion-doped lead-based antiferroelectric material to obtain a tape-cast ceramic powder, and then mixing it with the remaining raw materials for preparing the ceramic dielectric layer, performing tape-casting molding, and obtaining a ceramic dielectric film as the ceramic dielectric layer; S2, using a screen printer to print a ceramic dielectric film and an inner electrode A to obtain an A configuration, and printing a ceramic dielectric film and an inner electrode B to obtain a B configuration; S3, hot pressing and stacking the A configuration and the B configuration in sequence, cold isostatic pressing, slicing, debinding, sintering, coating the terminal electrodes, sintering the terminal electrodes, and obtaining an internal series type multilayer ceramic capacitor.

[0025] The thickness of the ceramic dielectric film is 5-30 μm.

[0026] The temperature of the hot pressing is 40-60° C., the pressure is 50-60 MPa, and the holding time is 5-30 min.

[0027] The debinding temperature is 500-600°C, the heating rate is 0.5-5°C / min, and the temperature is kept for 5-8 hours.

[0028] The sintering temperature is 1100-1250° C., the heating rate is 1-8° C. / min, the cooling rate is 1-10° C. / min, and the heat preservation is 2-4 hours. Optionally, the preparation of the tape-cast ceramic powder comprises the following steps: Weigh the corresponding element oxide powders, mix them evenly by wet high-energy ball milling, the mass ratio of material: ball: ethanol is (0.5-1.0): (1.0-2.0): (1.0-2.0), and the mixing time is 12-24 h to obtain a uniformly mixed solution; Drying is performed, and then grinding is performed, and the powder before calcination is obtained by passing through a 50-100 mesh sieve; Before pre-sintering, the powder is placed in a crucible and compacted, and multi-step pre-sintering is performed at a temperature of 750°C to 950°C, a heating rate of 1 to 8°C / min, a cooling rate of 1 to 10°C / min, and a holding time of 1 to 5 h to obtain a pre-sintered material; The obtained pre-burned material is ground, and after passing through a 50-100 mesh sieve, the sieved powder is mixed and crushed by wet high-energy ball milling, with a mass ratio of material: ball: ethanol of (0.5-1.0): (1.0-2.0): (1.0-2.0), and the mixing time is 12-24 h to obtain a mixed uniform solution; The obtained mixed uniform solution is dried, ground after drying, and passed through a 200-300 mesh sieve to obtain a tape-cast ceramic powder.

[0029] The stacking method of the stacking layers is: n ceramic dielectric layers + m layers of A configuration and B configuration alternately + n ceramic dielectric layers are stacked in sequence, and the ceramic dielectric layers on both sides are used to protect the internal series ceramic capacitors, wherein 5≤n≤15, 2≤m≤12.

[0030] Beneficial Effects 1. The overlapping portion of the inner electrode A and the inner electrode B perpendicular to the stacking direction is circular or elliptical, which effectively improves the breakdown field strength.

[0031] 2. The number of the inner electrodes A (21) arranged in the same layer is 2-4, and the obtained inner series multilayer ceramic capacitor has improved energy storage density and greatly prolonged service life.

[0032] 3. The multilayer ceramic capacitor of the present application has a simple preparation process, high operability and low overall cost.

[0033] 4. The multilayer ceramic capacitor designed by the present invention can greatly reduce the number of components connected in series and reduce the welding labor.

[0034] 5. The dielectric layer is a rare earth ion-doped lead-based antiferroelectric material system, and its general chemical formula is Pb(1.01-1.5zy)MzCay (Zr1-xSnx)0.995O3, where M includes any one or more of the rare earth elements La, Sm, Nd, Eu, Gd, Pr, Dy and Yb, which can further increase the energy storage density.

[0035] 6. This application starts from the structure of multilayer ceramic capacitors and specifically designs a corresponding screen printing template, wherein the size of the template can be freely adjusted according to needs.

[0036] 7. In the present application, rare earth ion doped lead-based antiferroelectric materials are combined to prepare an inner series type multilayer ceramic capacitor, which can be used as an energy storage capacitor and has good application prospects in pulse power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The following are structural diagrams of the circular opposed electrode inner-series multilayer ceramic capacitor prepared in Example 1, including (a) a top view, (b) a stereoscopic view, (c) a front view, and (d) a side view.

[0038] Figure 2 These are the molding structure diagrams of the circular opposed electrode multilayer ceramic capacitor prepared in Example 2, (a) top view cross-sectional view, (b) stereoscopic view, and (c) front view cross-sectional view.

[0039] Figure 3 1 is a diagram of the channel structure of the ceramic capacitor designed for Example 1, wherein from left to right are (a) A configuration, (b) B configuration, and (c) stacked configuration.

[0040] Figure 4 The inner electrode screen printing templates designed for Example 1 include, from left to right: (a) A-configuration screen printing template, and (b) B-configuration screen printing template.

[0041] Figure 5 The internal electrode configuration and screen printing template designed for Example 1 are as follows: (a) internal electrode configuration, (b) screen printing template.

[0042] Figure 6 The internal electrode configuration and screen printing template designed for Example 2 are as follows: (a) internal electrode configuration, (b) screen printing template.

[0043] Figure 7 This is a sequential process design diagram of screen printing and hot pressing lamination in Example 1, (a) screen printing, (b) screen printing product, (c) lamination.

[0044] Figure 8 2 are the breakdown electric field curves of the embodiments and comparative examples.

[0045] Fig. 9 The energy storage density and energy storage efficiency curves of the embodiments and comparative examples are shown.

[0046] Among them, 1. ceramic dielectric layer; 2. internal electrode; 3. end electrode; 21. internal electrode A; 22. internal electrode B. DETAILED DESCRIPTION

[0047] Example 1 An internal series type multilayer ceramic capacitor, such as Figure 1 As shown, the capacitor includes: a ceramic dielectric layer 1, an inner electrode 2 and an end electrode 3; the inner electrode 2 and the ceramic dielectric layer 1 are alternately stacked; the end electrode 3 is located on both sides perpendicular to the stacking direction and is connected to the inner electrode 2 through the ceramic dielectric layer 1, wherein the ceramic dielectric layer 1 is arranged on both sides parallel to the stacking direction of the capacitor; the length and width of the ceramic dielectric layer 1 are W and Y respectively, and the thickness is t; the inner electrode 2 includes an inner electrode A21 and an inner electrode B22, the length and width of the inner electrode A21 are d and h respectively, and the length and width of the inner electrode B22 are b and h respectively; the width of the pore between the inner electrode A21 and the end electrode 3 is a; wherein W=30mm, Y=15mm, d=1.5mm, b=2.7mm, h=1mm, t=25mm, c=0.7mm; the overlapping part of the inner electrode A and the inner electrode B perpendicular to the stacking direction is circular.

[0048] The layers of the multilayer ceramic capacitor are alternately stacked according to the internal electrode A21, the ceramic dielectric layer 1, the internal electrode B22, and the ceramic dielectric layer 1.

[0049] The inner electrodes A 21 are arranged in pairs in the same layer, and the margin of the paired electrodes is a, where a=1 mm.

[0050] like Figure 3 As shown, the inner electrode A 21 comprises a shoe-shaped electrode, and the inner electrode B 22 comprises an elliptical electrode.

[0051] The raw materials for preparing the ceramic dielectric layer 1 include rare earth ion-doped lead-based antiferroelectric materials, the general chemical formula of which is Pb (1.01 - 1.5z-y) M z Ca y (Zr 1-x Sn x ) 0.995 O 3 , wherein M is the rare earth element La, z=0.02, y=0.03, x=0.4. According to the weight percentage of the rare earth ion-doped lead-based antiferroelectric material, the raw materials for preparing the ceramic dielectric layer 1, according to the weight percentage, also include 30% of xylene and 30% of anhydrous ethanol as solvents, 0.7% of tributyl phosphate as a dispersant, 7% of polyvinyl butyral (Sinopharm Chemical Reagent Co., Ltd.) as a binder, and a plasticizer consisting of 3% of polyethylene glycol (Sinopharm Chemical Reagent Co., Ltd.), 3% of tributyl phthalate and 4% of cyclohexanone by weight.

[0052] The inner electrode 2 is a Pt electrode, and the terminal electrode 3 is a silver electrode.

[0053] The method for preparing the inner series type multilayer ceramic capacitor comprises the following steps: S1, pre-treating the material of the rare earth ion-doped lead-based antiferroelectric material to obtain a cast ceramic powder, and then mixing it with the remaining raw materials for preparing the ceramic dielectric layer 1, first vacuum-debubbling the obtained cast slurry, and then casting it using a casting machine, adjusting the casting machine to obtain a film of the required thickness, which can be about 20 µm; cutting the obtained film into rectangles with a length and width of W and Y respectively, to obtain a dielectric layer film to obtain a ceramic dielectric film; S2, print the template using a screen printer ( Figure 4 ) The ceramic dielectric film and the inner electrode A 21 are printed to obtain the A configuration ( Figure 3 ), the ceramic dielectric film and the inner electrode B 22 are printed to obtain the B configuration; S3, hot pressing and laminating the A configuration and the B configuration in sequence, cold isostatic pressing, slicing, debinding, sintering, coating the terminal electrode 3, sintering the terminal electrode 3, and obtaining an internal series type multilayer ceramic capacitor.

[0054] The tape-cast ceramic powder is a rare earth ion-doped lead-based antiferroelectric material.

[0055] Preparation of the tape-cast ceramic powder: weigh an appropriate amount of CaCO 3 Powder,La 2 O 3 Powder, Pb 3 O 4 Powder, ZrO 2 Powder, SnO 2 The powder is used as the raw material powder, wherein z=0.02, y=0.03, and x=0.4, and the ingredients are prepared according to the stoichiometric amount of Pb, La, Ca, Zr, and Sn in the chemical formula; wet high-energy ball milling is performed to mix uniformly, the mass ratio of material: ball: ethanol is 1:1:1.5, and the mixing time is 20 h to obtain a uniformly mixed solution; the uniformly mixed solution is dried, and then ground and passed through an 80-mesh sieve to obtain a pre-sintered powder; the pre-sintered powder is placed in a crucible for compaction, and multi-step pre-sintering is performed, after the temperature is increased to 950°C at 4°C / min, the temperature is decreased to 900°C at 8°C / min, the temperature is decreased to 850°C at 6°C / min, the temperature is decreased to 800°C at 5°C / min, and the temperature is kept for 1.5 h to obtain a pre-burned material; the pre-burned material is ground, and after passing through an 80-mesh sieve, the sieved powder is mixed and crushed by wet high-energy ball milling, the mass ratio of material: ball: ethanol is 1:1.2:1.5, the mixing time is 20 h, and a mixed uniform solution is obtained; the obtained mixed uniform solution is dried, ground after drying, and passed through a 300-mesh sieve to obtain a cast ceramic powder.

[0056] The specific steps of step S3 are: hot pressing and laminating the A configuration and the B configuration, such as Figure 7As shown, the stacking method is n layers of blank dielectric layers + m layers of A configuration and B configuration alternating + n layers of blank dielectric layers, and the blank layer is used to protect the inner series type ceramic capacitor, wherein n=10, m=4; the number of effective dielectric layers is 3, the hot pressing temperature is 50°C, the pressure is 60 MPa, and the holding time is 10 min; static pressing, the pressure is 200 MPa, the holding time is 15 min, and then cutting is performed to obtain the inner series type multilayer ceramic capacitor green body; the green body is subjected to debinding sintering, and the extrusion stacking method is used for sintering, the debinding temperature is 550°C, the heating rate is 5°C / min, and the heat preservation is 6 h, the sintering temperature is 1160°C, the heating rate is 5°C / min, the cooling rate is 8°C / min, and the heat preservation is 3 h to obtain the inner series type multilayer ceramic capacitor green body; the cut surface of the green body is polished, and after polishing, the end electrode 3 is coated, and after the end electrode 3 is coated, the end electrode 3 is sintered to obtain a single inner series type multilayer ceramic capacitor.

[0057] Example 2 The specific implementation is the same as in Example 1; the difference is that in Example 2 b =3 mm, d =1.7 mm, h =1.3 mm; M is Nd, x=0.4, z=0.008, y=0.03.

[0058] Example 3 The specific implementation is the same as in Example 1; the difference is that in Example 2, b =2 mm, d =1.3 mm, h =0.8 mm; said M is Sm, x=0.4, z=0.008, y=0.03.

[0059] Comparative Example 1 The specific implementation method is the same as that of Example 1; except that, in Comparative Example 1, Figure 5 The traditional rectangular electrode template shown is used for screen printing of internal electrodes. A single electrode is a rectangle with a length of m and a width of n. The dielectric layer film is screen printed with internal electrodes, where: m=4 mm, n=1.5 mm. The dielectric layer printed with electrodes is subjected to hot pressing lamination, cold isostatic pressing, slicing, debinding, sintering, end electrode coating, and sintering end electrodes to obtain a traditional rectangular opposed electrode multilayer ceramic capacitor.

[0060] Comparative Example 2 The specific implementation method is the same as in Example 1; the difference is that in Comparative Example 2, Figure 6The designed screen printing template is shown in the figure. A single electrode is an ellipse with a length of g and a width of e. The inner electrode is screen printed on the dielectric layer film, where: g = 2.7 mm, e = 1 mm. The dielectric layer printed with the electrode is hot pressed and laminated, cold isostatically pressed, sliced, debonded, sintered, coated with end electrodes, and sintered end electrodes to obtain a circular opposed electrode multilayer ceramic capacitor, as shown in FIG. Figure 2 shown.

[0061] Performance Testing Methods The following performance tests were carried out in the embodiments and comparative examples, and the test data are listed in Table 1.

[0062] Test the electrical properties of capacitors (Radiant's ferroelectric integrated test system): Breakdown electric field ( Figure 8 ), energy storage density and energy storage efficiency ( Fig. 9 and Table 1).

[0063] Table 1

[0064] Combining Table 1 and Figure 8-9 It can be obtained that the internal series multilayer ceramic capacitor prepared in the present application has excellent breakdown electric field, energy storage density and energy storage efficiency.

Claims

1. An inner series type multilayer ceramic capacitor, characterized in that: include: A ceramic dielectric layer (1), an internal electrode (2) and an end electrode (3); the internal electrode (2) and the ceramic dielectric layer (1) are alternately stacked; the end electrode (3) is located on both sides perpendicular to the stacking direction and is connected to the internal electrode (2) through the ceramic dielectric layer (1), wherein the ceramic dielectric layer (1) is arranged on both sides of the capacitor parallel to the stacking direction; and the overlapping portion of the internal electrode A (21) and the internal electrode B (22) perpendicular to the stacking direction is circular or elliptical.

2. The inner series type multilayer ceramic capacitor according to claim 1, characterized in that: The number of the inner electrodes A (21) arranged in the same layer is 2-4.

3. The inner series type multilayer ceramic capacitor according to claim 2, characterized in that: The spacing between the inner electrodes A (21) in the same layer is c, and 0.5 mm≤c≤3 mm.

4. The inner series type multilayer ceramic capacitor according to claim 3, characterized in that: 0.5 mm≤c≤1.5 mm.

5. The inner series type multilayer ceramic capacitor according to claim 1, characterized in that: The width of the gap between the inner electrode A (21) and the end electrode (3) is a, 0.5 mm≤a≤2 mm.

6. The inner series type multilayer ceramic capacitor according to claim 1 or 5, characterized in that: The length and width of the ceramic dielectric layer (1) are W and Y respectively, and the thickness is t; the inner electrode (2) comprises an inner electrode A (21) and an inner electrode B (22), wherein 10 mm≤W≤60 mm, 10 mm≤Y≤60 mm, and 8 mm≤t≤25 mm.

7. The inner series multilayer ceramic capacitor according to claim 6, wherein the length and width of the inner electrode A (21) are d and h respectively, the length and width of the inner electrode B (22) are b and h respectively, 1 mm≤d≤5 mm, 2 mm≤b≤10 mm, 0.4 mm≤h≤4 mm.

8. The inner series type multilayer ceramic capacitor according to claim 7, characterized in that: 15mm≤t≤25mm.

9. The inner series type multilayer ceramic capacitor according to claim 8, characterized in that: The layers of the multilayer ceramic capacitor are alternately stacked according to the internal electrode A (21), the ceramic dielectric layer (1), the internal electrode B (22), and the ceramic dielectric layer (1).

10. The inner series type multilayer ceramic capacitor according to claim 9, characterized in that: The number of layers of the inner electrode A (21) is 2-12.

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