JP2017073470A - Capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor to which a high voltage can be applied.SOLUTION: In a capacitor 1, the area of first and second internal electrode layers 9 and 11, which are floating electrodes, is 95% or more of the area of first and second principal faces 19 and 21 along the first and second internal electrode layers 9 and 11 (i.e. the area of surfaces of upside and downside solid electrolyte layers 3 and 7 of outermost layers of a base 17). This makes it difficult for a lithium ion to move across the first and second internal electrode layers 9 and 11, which are floating electrodes with a voltage applied between first and second external electrodes 13 and 15 of the capacitor 1. Thus, a voltage applied to the capacitor 1 is almost uniformly distributed to interfaces of the external electrodes 13 and 15 and the internal electrode layers 9 and 11. Therefore, the oxidizing/reducing reaction which tends to be caused at each electrode interface can be suppressed. As a result, a voltage applied to the capacitor 1 can be made higher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a capacitor (capacitor) that stores and discharges electric charge, and more particularly to a capacitor using a solid electrolyte having lithium ion conductivity.

  Conventionally, a capacitor using an electrolyte material is known as a capacitor using an electrolyte material. However, in recent years, for example, a solid capacitor having a pair of electrodes on the surface of a dielectric layer is known. It has been. A solid capacitor is also known in which a pair of electrodes is provided on the surface of a solid electrolyte layer having lithium ion conductivity.

  As this type of solid capacitor, a capacitor having a laminated structure in which solid electrolytes and electrodes (internal electrodes) are alternately laminated, that is, a dielectric capacitor having a MLCC (Multi-Layer Ceramic Capacitor) structure (so-called side-drawing type solid capacitor) ) Is disclosed (see Patent Documents 1 to 4).

  In these MLCC structure solid capacitors, each internal electrode is electrically connected to each external electrode formed on a pair of side surfaces outside the solid capacitor. That is, one internal electrode is connected to one external electrode, and the other internal electrode is connected to the other external electrode. For example, in a capacitor in which a single layer structure (capacitor portion) in which a pair of electrodes are provided on both sides of a single dielectric layer or the like is disposed in a plurality of layers, the capacitor portions are connected in parallel.

Further, for example, Patent Document 1 below discloses a technique for disposing a float electrode in a capacitor in order to prevent a withstand voltage drop due to stacking deviation of each capacitor portion.
Further, in Patent Documents 2 and 3 below, in a dielectric capacitor, in order to prevent an electric field from concentrating on an end portion of the internal electrode and causing dielectric breakdown, a float electrode is disposed in the capacitor to increase the withstand voltage of the capacitor. Techniques for improving are disclosed.

  Patent Document 4 below discloses the basic structure and characteristics of a solid electrolyte capacitor (here, an electric double layer capacitor) using a solid electrolyte between electrodes.

JP 07-135124 A Japanese Patent Laid-Open No. 01-220421 JP-A-01-220422 JP 2008-130844 A

However, the above-described prior art has the following problems, and improvements are desired.
Specifically, in the solid electrolyte capacitor described in the above cited reference 4, when a voltage higher than a certain voltage is applied, an oxidation-reduction reaction occurs at the electrode interface. Therefore, the voltage at which the capacitor can operate stably is low, and the capacitor is high. There was a problem that voltage could not be applied.

  As a countermeasure, it is conceivable to employ a float electrode structure as described in the above cited documents 1 to 3 for a solid electrolyte capacitor. In this case, ions are connected to the interface between the electrode connected to the external power source and the float electrode. Therefore, there is a possibility that the voltage applied to the capacitor is distributed to each electrode interface and the oxidation-reduction reaction at each electrode interface is suppressed.

  However, even when the float electrodes described in the above cited references 1 to 3 are employed, the suppression of the oxidation-reduction reaction at the electrode interface is not sufficient, and it is not easy to apply a high voltage to the capacitor.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a capacitor capable of applying a high voltage.

  (1) In the capacitor according to the first aspect of the present invention, a solid electrolyte layer mainly composed of a solid electrolyte having lithium ion conductivity and an internal electrode layer are alternately stacked, and at least one surface in the stacking direction. And a first external electrode and a second external electrode formed on the solid electrolyte layer on one surface side and the other surface side of the substrate, respectively. The internal electrode layer is an independent float electrode that is electrically separated from the external electrodes, and is disposed along the one or the other surface of the substrate. The area of the internal electrode layer is 95% or more of the area of the surface.

  The capacitor according to the first aspect includes a so-called solid electrolyte capacitor with a float electrode. In this capacitor, the area of the internal electrode layer that is a float electrode is equal to one surface along the internal electrode layer ( For example, it is 95% or more of the area of the first main surface) or the other surface (for example, the second main surface) (that is, the area of the solid electrolyte layer as the outermost layer of the substrate).

  This makes it difficult for lithium ions to move beyond the float electrode when a voltage is applied to both external electrodes of the capacitor, so the voltage applied to the capacitor is distributed almost evenly at the interface between the external electrode and the float electrode. Is done. Therefore, the oxidation-reduction reaction that easily occurs at each electrode interface can be suppressed, and as a result, the voltage applied to the capacitor can be increased.

  Here, the “solid electrolyte layer” is a layer having characteristics as a solid electrolyte (characteristics capable of moving ions (here, lithium ions) by an electric field applied from the outside: ion conductivity).

The “main component” indicates that the corresponding component is the most abundant component (for example, 50% by volume or more).
Furthermore, the internal electrode layer is an electrode layer disposed inside the capacitor.

The float electrode is an electrode that is not electrically connected to the surroundings, that is, an insulated electrode (floating electrode: floating electrode).
(2) In the capacitor according to the second aspect of the present invention, the base has a plurality of the float electrodes.

  In the second aspect, the base has a structure having a plurality of float electrodes. That is, a first capacitor portion having a solid electrolyte layer between the first external electrode and the internal electrode layer, and a second capacitor portion having a solid electrolyte layer between the second external electrode and the internal electrode layer. In addition, one or a plurality of third capacitor portions having a solid electrolyte layer between a pair of opposed internal electrode layers can be employed.

  As a result, the capacitor has three or more capacitor portions, so that the applied voltage of the capacitor can be increased according to the number of float electrodes (that is, as the number increases).

In addition, when there are a plurality of float electrodes, there is an advantage that the capacitor does not become short-circuited unless all the float electrodes are short-circuited.
(3) In the capacitor according to the third aspect of the present invention, the float electrode is exposed on a side surface between the one surface and the other surface.

In the third aspect, since the float electrode is exposed to the side surface, it is possible to effectively suppress the movement of lithium ions so as to avoid the float electrode.
Thereby, the applied voltage of the capacitor can be further increased.

It is a perspective view which shows the capacitor of 1st Embodiment. It is sectional drawing which fractures | ruptures the capacitor of 1st Embodiment in the lamination direction (Z direction) of each layer, and shows the torn surface. (A) is sectional drawing which fractures | ruptures the capacitor of 2nd Embodiment in the lamination direction of each layer, and shows the fracture surface, (b) is a cross section which fractures | ruptures the capacitor of 3rd Embodiment in the lamination direction of each layer, and shows the fracture surface FIG. It is a graph which shows the relationship between the applied voltage of a capacitor, and the electric current which flows into a capacitor about the sample of Example 1 and Comparative Examples 1-3. It is a graph which shows the relationship between the applied voltage of a capacitor, and the electric current which flows into a capacitor about the sample of Example 2 and Comparative Examples 4-6.

[First Embodiment]
a) First, the configuration of the capacitor according to the first embodiment will be described.
In the following description, explanation will be made using each direction such as the top and bottom of the figure, but each direction is only a direction defined for concisely explaining the relative positional relationship of each part. The direction in which the capacitor is oriented is arbitrary. For example, “upper and lower” indicating directions in the following description is the same as the “upper and lower” directions in FIG.

As shown in FIG. 1, the capacitor 1 according to the first embodiment is a monolithic ceramic chip capacitor having a flat plate shape (cuboid shape).
This capacitor 1 includes three solid electrolyte layers 3, 5, 7 and two internal electrode layers 9, 11 and two external electrodes 13, 15 in the vertical direction (stacking direction: Z direction) in FIG. Are laminated.

  That is, the capacitor 1 includes the solid electrolyte layers 3, 5, 7 and the internal electrode layers 9, 11 that are alternately stacked, and the upper solid electrolyte layer 3 and the lower side on both sides (as the outermost layer) in the stacking direction. A substrate 17 on which the solid electrolyte layer 7 is disposed is provided. Then, the first external electrode 13 is formed on one surface 19 (first main surface on the upper side in FIG. 2) in the stacking direction of the base body 17, and the other surface 21 (second main surface on the lower side in FIG. 2): A second external electrode 15 is formed on the back surface.

  Specifically, the capacitor 1 includes a central solid electrolyte layer 5 at the center in the stacking direction, a first internal electrode layer 9 is disposed above the central solid electrolyte layer 5, and a first internal electrode layer 9 is The upper solid electrolyte layer 3 (which constitutes one main surface 19) is disposed, and the first external electrode 13 is disposed above the upper solid electrolyte layer 3.

  On the other hand, the second internal electrode layer 11 is disposed below the central solid electrolyte layer 5, and the lower solid electrolyte layer 7 (which constitutes the second main surface 21) is disposed below the second internal electrode layer 11. The second external electrode 15 is disposed below the lower solid electrolyte layer 7.

Hereinafter, each configuration will be described in more detail.
The upper solid electrolyte layer 3, the central solid electrolyte layer 5, and the lower solid electrolyte layer 7 are solid electrolytes having lithium ion conductivity, such as Li _1.5 Al _0.5 Ge _0.5 (PO ₄ ) ₃ (hereinafter referred to as LAGP). May be written).

  The thicknesses (Z1, Z3) of the upper and lower solid electrolyte layers 3 and 7 are, for example, 150 μm, and the thickness (Z2) of the central solid electrolyte layer 5 is, for example, 16.5 μm. In addition, each thickness is not limited to this, For example, it is good also considering the thickness of each solid electrolyte layer 3, 5, 7 as the same.

The first internal electrode layer 9 and the second internal electrode layer 11 are made of, for example, platinum (Pt), and the first external electrode 13 and the second external electrode 15 are also made of platinum.
Separately, the solid electrolyte layers 3, 5, 7 are, for example, Li ₇ La ₃ Zr ₂ O ₁₂ (hereinafter sometimes referred to as LLZ), and the internal electrode layers 9, 11 are, for example, nickel (Ni ).

In particular, in the first embodiment, each internal electrode layer 9, 11 is an independent float electrode that is not electrically connected to each external electrode 13, 15.
The solid electrolyte layers 3, 5, 7, the internal electrode layers 9, 11 and the external electrodes 13, 15 are arranged in parallel.

  Among these, the 1st internal electrode layer 9 is arrange | positioned along the 1st main surface 19 of the base | substrate 17, The area of the 1st internal electrode layer 9 is the area (namely, upper side solid electrolyte layer of the 1st main surface 19). 3 of the upper surface 3).

  Similarly, for example, the second internal electrode layer 11 is disposed along the second main surface 21 of the substrate 17, and the area of the second internal electrode layer 11 is the area of the second main surface 21 (that is, the lower solid). 95% or more of the area of the lower surface of the electrolyte layer 7).

  Furthermore, the end portions of the internal electrode layers 9 and 11 (that is, the end portions in the plane direction (XY direction) in which the internal electrode layers 9 and 11 spread) are the side surfaces of the capacitor 1 (the first main surface 19 and the second main surface). The side surface between the base member 17 and the base member 17 is exposed to the side surface 23 extending in the XY direction and extending in the Z direction. The internal electrode layers 9 and 11 do not have to be exposed on the side surface 23.

b) Next, only the outline of the manufacturing method of the capacitor 1 of the first embodiment will be briefly described.
The contents of each process, which is a manufacturing procedure of the capacitor 1, will be described in detail in Examples 1 and 2 described later. For example, in the case of Example 1, the following procedures (1) to (8) can be adopted. In the case of Example 2, the following procedures (1) to (7) can be adopted.

  In the following description, the case where the base body 17 is manufactured using a flat base material having a plurality of unfired base bodies will be described as an example. However, the present invention is not limited to this. For example, you may produce the base | substrate 17 independently.

(1) Calcination powder production process (2) Ground powder production process (3) Slurry production process (4) Sheet production process (5) Internal electrode printing process (6) Laminate production process (7) Firing process (8) External Electrode Formation Step c) Next, the effect of the capacitor 1 of the first embodiment will be described.

  In the capacitor 1 of the first embodiment, the areas of the first and second internal electrode layers 9 and 11 that are float electrodes are the first and second main electrodes along the first and second internal electrode layers 9 and 11. It is 95% or more of the area of the surfaces 19 and 21 (that is, the surface area of the upper and lower solid electrolyte layers 3 and 7 of the outermost layer of the substrate 17).

Thereby, when a voltage is applied to the first and second external electrodes 13 and 15 of the capacitor 1 (for example, when a direct current or an alternating current with a low frequency (for example, 1 Hz or less) is applied), lithium ions are float electrodes. It becomes difficult to move beyond the first and second internal electrode layers 9 and 11. Therefore, the voltage applied to the capacitor 1 is distributed almost evenly to the interface between the first and second external electrodes 13 and 15 and the first and second internal electrode layers 9 and 11.
Therefore, since the oxidation-reduction reaction that easily occurs at each electrode interface can be suppressed, the voltage applied to the capacitor 1 can be increased as a result.

  Further, in the capacitor 1 of the first embodiment, since a plurality (two layers) of float electrodes are formed on the substrate 17, the applied voltage of the capacitor 1 is made higher than in the case of a single layer of float electrodes. It becomes possible to do. In addition, when there are a plurality of float electrodes, there is an advantage that the capacitor will not be short-circuited unless all the float electrodes are short-circuited.

  Furthermore, in the capacitor 1 of the first embodiment, the float electrode is exposed at the side surface 23 between the two main surfaces 19 and 21, so that lithium ions can effectively move so as to avoid the float electrode. Can be suppressed. As a result, the applied voltage of the capacitor 1 can be further increased.

In addition, the capacitor 1 of the first embodiment has an advantage that the manufacturing process can be simplified and the manufacturing cost can be reduced because it is not necessary to form the electrode patterning and side electrodes used in the MLCC structure.
[Second Embodiment]
Next, the capacitor of the second embodiment will be described, but the description of the same content as that of the first embodiment will be omitted. In addition, the same number is used for the same structure as 1st Embodiment.

  As shown in FIG. 3A, the capacitor 31 of the second embodiment includes a base 33, and the first external electrode 13 and the second external on both sides in the stacking direction of the base 33, as in the first embodiment. An electrode 15 is provided.

  In particular, in the second embodiment, the substrate 33 includes the upper solid electrolyte layer 3 and the lower solid electrolyte layer 7 similar to those in the first embodiment, and between the upper solid electrolyte layer 3 and the lower solid electrolyte layer 7. 1 includes an internal electrode layer 35 (which is a float electrode).

The second embodiment has the same effects as the first embodiment and has the advantage that the structure is simple and the manufacturing is easy.
[Third Embodiment]
Next, the capacitor of the third embodiment will be described, but the description of the same content as that of the first embodiment will be omitted. In addition, the same number is used for the same structure as 1st Embodiment.

  As shown in FIG. 3B, the capacitor 41 according to the third embodiment includes a base body 43, and similarly to the first embodiment, the first external electrode 13 and the second external electrode are formed on both sides of the base body 43 in the stacking direction. An electrode 15 is provided.

  In particular, in the third embodiment, the base body 43 includes the upper solid electrolyte layer 3 and the lower solid electrolyte layer 7 similar to those of the first embodiment, and between the upper solid electrolyte layer 3 and the lower solid electrolyte layer 7. Are provided with a plurality (two layers) of solid electrolyte layers (that is, the first central solid electrolyte layer 45 and the second central solid electrolyte layer 47).

  In addition, among the total of four solid electrolyte layers 3, 45, 47, and 7, between the adjacent solid electrolyte layers 3, 45, 47, and 7, the first and second (which are float electrodes), respectively. The third internal electrode layers 49, 51 and 53 are laminated.

  The area of each internal electrode layer 49, 51, 53 is, for example, the same as that of each solid electrolyte layer 3, 45, 47, 7 (100%), but each solid electrolyte layer 3, 45, 47, 7 It may be 95% or more of the area.

  The third embodiment has the same effects as the first embodiment, and has more float electrodes than the first embodiment, so that a higher voltage than the first embodiment can be applied to the capacitor 41. Further, since the area of each internal electrode layer 49, 51, 53 is the same (100%) as the area of each solid electrolyte layer 3, 45, 47, 7, a high voltage is applied to the capacitor 41 also from this point. can do.

  Therefore, there is an advantage that the electric capacity (capacitance) can be further increased as compared with the first embodiment.

Next, Example 1 of the capacitor will be described in detail.
Here, the capacitor of Example 1 having a structure corresponding to the first embodiment (however, the solid electrolyte is LAGP) and the capacitors of Comparative Examples 1 to 3 having a configuration that is not the present invention will be described.

a) First, a method for manufacturing the capacitor of Example 1 will be described.
<Calcined powder production process>
First, in order to produce Li _1.5 Al _0.5 Ge _0.5 (PO ₄ ) ₃ (LAGP), which is a solid electrolyte, lithium carbonate, germanium oxide as starting materials so as to have a molar ratio of LAGP A predetermined amount of aluminum oxide and diammonium hydrogen phosphate were weighed and mixed to prepare a mixed material.

  The mixed material was mixed with ethyl alcohol using a nylon pot and zirconia cobblestone. After the mixture was dried, it was calcined by holding it at 900 ° C. for 2 hours in an air atmosphere with an alumina crucible to prepare a calcined powder of LAGP.

<Crushed powder preparation process>
Next, the calcined powder of LAGP was pulverized for 36 hours using a nylon pot and zirconia spherulite together with ethyl alcohol and dried to prepare a pulverized powder of LAGP.

<Slurry production process>
Next, the pulverized powder of LAGP, a binder (acrylic resin), and a plasticizer (dioctyl phthalate) were mixed with a methyl ethyl ketone / toluene mixed solvent to prepare a slurry of LAGP.

<Sheet preparation process>
Next, the slurry of LAGP was applied by a doctor blade method to a carrier film made of PET having a Si treatment on one side to produce a sheet having a thickness of about 30 μm.

<Internal electrode printing process>
Next, this sheet was punched into a predetermined size, and a Pt electrode material serving as an internal electrode layer was printed on one surface of the sheet by screen printing so as to be overlapped five times with a predetermined pattern. The material of the Pt electrode is a paste formed by adding a binder and a solvent at a ratio of 4.5 vol% of Pt powder.

<Laminated body production process>
Next, two sheets of screen-printed Pt electrode material and 17 sheets punched out were prepared, and the LAGP stack of Example 1 was laminated so as to have the structure of the first embodiment (see FIG. 2). The body was made.

  Here, as Comparative Example 1, a laminate of 19 sheets on which the Pt electrode material was not printed was produced, and as Comparative Example 2, two sheets on which the Pt electrode material was printed once and a sheet that was punched out. A laminate of 17 sheets was produced, and as Comparative Example 3, a laminate of 2 sheets printed with the Pt electrode material three times and 17 sheets just punched out was produced.

  Note that, when the number of times of printing differs, the coverage described later changes. That is, the coverage increases as the number of times of printing increases. Accordingly, the coverage can be adjusted by examining the relationship between the number of times of printing (in the same material and conditions) and the coverage in advance.

  Each of the laminates of Example 1 and Comparative Examples 1 to 3 was heated to 80 ° C. by WIP (Warm Isostatic Press) and held at 196 MPa for 1000 seconds to perform high pressure pressing to produce each base material. did.

After that, each base material was subjected to break processing along the product shape with a CO ₂ laser processing machine, and was cut into individual pieces along the break grooves to produce unfired substrates.
<Baking process>
Next, the unfired substrate was heated to 280 ° C. in an air atmosphere to remove the binder, and then baked by holding at 850 ° C. for 20 hours in the air atmosphere.

<External electrode formation process>
Next, first and second external electrodes were formed by Pt sputtering on the front surface (first main surface) and the back surface (second main surface) of the fired substrate.

  In this way, the capacitor of Example 1 having a flat plate shape of 5 mm in length, 10 mm in width, and 0.32 mm in thickness, in which the float electrode was arranged, was produced. In addition, the capacitor of Comparative Examples 1-3 was similarly produced from each said laminated body.

b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.
<Section observation>
In this evaluation, in order to investigate the coverage of the float electrode, cross-sectional observation of each capacitor sample of Example 1 and Comparative Examples 1 to 3 was performed using Nikon's Nexiv (VMR-6555). In addition, this cross section is a cross section when the capacitor (and hence the base body) is broken along the stacking direction (Z direction).

  Here, the coverage is a value indicating the ratio of the area where the float electrode exists and the area where it does not exist on the plane parallel to the float electrode. That is, when the float electrode (internal electrode layer) is viewed from the cross section, the length L where the electrodes are connected and the length l where the electrodes are completely disconnected are used, and “{L / (l + L)} × 100”. Thus, the coverage (%) was obtained.

Since the float electrode is parallel to both main surfaces of the substrate, this coverage corresponds to “the ratio of the area of the internal electrode layer to the area of the main surface of the substrate”.
As a result of cross-sectional observation, the coverage of each sample was 0% in Comparative Example 1, 69.6% in Comparative Example 2, 93.5% in Comparative Example 3, and 98.3% in Example 1. In addition, when calculating | requiring a coverage, each sample observed the cross section of multiple places (five places) at random, and calculated | required the average value. Although it is desirable that the number of observation points on the cross section is large, it is sufficient that there are at least five observation points.

<Current-voltage characteristics>
In addition, in order to measure the withstand voltage of each sample, a voltage was applied to the external electrode of each sample at a sweep rate of 5 mV / s from 0 V to 10 V using a Solartron 1287, and the current at that time was measured. did. The result is shown in FIG.

As is clear from FIG. 4, Comparative Example 1 had current peaks at about 3.6 V and about 4.6 V, and the current increased drastically as the voltage increased.
In Comparative Examples 2 and 3, it was confirmed that when the coverage was high, the peak of the current shifted to the high voltage side and the peak height was low as compared with Comparative Example 1.

  Moreover, about the comparative examples 1-3, when the sample was confirmed after the voltage application, the negative electrode side was blackened. Therefore, it is presumed that when a voltage was applied to the sample, an oxidation-reduction reaction occurred at the interface between the solid electrolyte and the negative electrode and a reaction current was flowing.

  On the other hand, in Example 1, there was no sharp increase or peak in current up to 10 V, and the negative electrode after voltage application did not change. Therefore, in Example 1, the effect is expressed in the float electrode, and it is estimated that the reaction at the interface between the solid electrolyte and the negative electrode is suppressed.

Next, a second embodiment of the capacitor will be described in detail.
Here, the capacitor of Example 2 having a structure corresponding to the first embodiment (however, the solid electrolyte is LLZ) and the capacitors of Comparative Examples 4 to 6 having a configuration that is not the present invention will be described.

a) First, a method for manufacturing the capacitor of the second embodiment will be described.
<Calcined powder production process>
First, in order to produce Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) which is a solid electrolyte, a predetermined amount of lithium carbonate, lanthanum hydroxide, and zirconium oxide are weighed as starting materials so as to have a molar ratio of LLZ. And mixed to prepare a mixed material.

  The mixed material was mixed with ethyl alcohol using a nylon pot and zirconia cobblestone. After the mixture was dried, it was calcined by holding at 1100 ° C. for 10 hours in an air atmosphere with an alumina crucible to prepare a LLZ calcined powder.

<Crushed powder preparation process>
Next, the calcined powder of LLZ was pulverized for 36 hours using a nylon pot and zirconia spherulite together with methyl ethyl ketone and dried to prepare a pulverized powder of LLZ.

<Slurry production process>
Next, pulverized powder of LLZ, a binder (butyral resin), and a plasticizer (dioctyl phthalate) were mixed with a methyl ethyl ketone / toluene mixed solvent to prepare a slurry of LLZ.

<Sheet preparation process>
Next, the slurry of LLZ was applied to a PET carrier film Si-treated on one side by a doctor blade method to produce a sheet having a thickness of about 30 μm.

<Internal electrode printing process>
Next, this sheet was punched into a predetermined size, and a Ni electrode material serving as an internal electrode layer was printed on one surface of the sheet by screen printing in a predetermined pattern five times. The material for the Ni electrode is a paste obtained by adding a binder and a solvent at a ratio of 4.3 vol% Ni powder.

<Laminated body production process>
Next, two sheets of Ni electrode material screen-printed and 17 punched sheets were prepared, and the structure of the first embodiment (see FIG. 2) was used, so that the LLZ layer of Example 2 was laminated. The body was made.

  Here, as Comparative Example 4, a laminate of 19 sheets on which no Ni electrode material was printed was prepared, and as Comparative Example 5, two sheets of Ni electrode material printed once and a sheet that had only been punched out A laminate of 17 sheets was produced, and as Comparative Example 6, a laminate of 2 sheets of Ni electrode material printed three times and 17 sheets of punched sheets was produced.

And each laminated body of these Examples 2 and Comparative Examples 4-6 was hold | maintained at 196 MPa for 1000 seconds, heating to 80 degreeC by WIP, and carried out the high pressure press, and produced each base material.
Next, the surface of each base material and the back surface were screen-printed with a material for a Ni electrode serving as an external electrode in a predetermined pattern.

After that, each base material was subjected to break processing along the product shape with a CO ₂ laser processing machine, and was cut into individual pieces along the break grooves to produce unfired substrates.
<Baking process>
Next, the unfired substrate was heated to 300 ° C. in an air atmosphere to remove the binder, and then fired by holding at 1200 ° C. for 2 hours in a hydrogen-nitrogen mixed atmosphere.

  Thus, a plate-like capacitor of Example 2 having a vertical length of 5 mm, a horizontal width of 10 mm, and a thickness of 0.32 mm in which a float electrode was arranged was manufactured. In addition, the capacitors of Comparative Examples 4 to 6 were produced in the same manner from the respective laminates.

b) Next, evaluation (experimental example) for confirming the performance of the capacitor will be described.
<Section observation>
In the same manner as in Example 1, in order to investigate the coverage of the float electrode, the cross-sectional observation of each capacitor sample of Example 2 and Comparative Examples 4 to 6 was performed using Nexiv (VMR-6555) manufactured by Nikon. The coverage was determined.

  As a result of cross-sectional observation, the coverage of each sample was 0% in Comparative Example 4, 65.6% in Comparative Example 5, 90.1% in Comparative Example 6, and 95.3% in Example 2. In addition, the covering rate observed the cross section of multiple places (5 places) at random for each sample, and calculated | required the average value.

<Current-voltage characteristics>
Similarly to Example 1, in order to measure the withstand voltage of each sample, a voltage was applied to the external electrode of each sample at a sweep rate of 5 mV / s from 0 V to 10 V using Solartron 1287. The current at that time was measured. The result is shown in FIG.

As is clear from FIG. 5, Comparative Example 4 had current peaks at about 2 V, about 3 V, and about 4 V, and the current increased dramatically as the voltage increased.
Similar to LAGP, it was confirmed that in Comparative Examples 5 and 6, when the coverage was higher than that in Comparative Example 4, the current peak shifted to the high voltage side and the peak height was also low.

  Moreover, about these comparative examples 4-6, when the sample was confirmed after the voltage application, the negative electrode side was blackened. Therefore, it is presumed that when a voltage was applied to the sample, an oxidation-reduction reaction occurred at the interface between the solid electrolyte and the negative electrode and a reaction current was flowing.

  On the other hand, in Example 2, there was no sharp increase or peak in current up to 5 V, and the negative electrode after voltage application did not change. Therefore, in Example 2, it is presumed that the float electrode was effective, and the reaction at the interface between the solid electrolyte and the negative electrode was suppressed.

  As a result of the above Examples 1 and 2, etc., when the coverage of the float electrode is increased, the effect of the float electrode is increased. When the coverage is 95% or more, the effect of the float electrode is exhibited up to a direct current or a low frequency. I understand that I can do it. That is, it can be seen that the oxidation-reduction reaction at the interface between the solid electrolyte and the electrode is suppressed, and the operating limit voltage of the capacitor is improved.

In addition, this invention is not limited to the said embodiment and Example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
(1) For example, the number of float electrodes is not limited to the above-described embodiment, and may be changed as appropriate.

(2) As the solid electrolyte, Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) and Li _1.5 Al _0.5 Ge _0.5 (PO ₄ ) ₃ (LAGP) can be used. The lithium ion conductor can be used.

For _{example, Li 1 + x Al x Ge} 2-x (PO 4) 3, Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP), Li x Zr y Nb z (PO 4) 3 (LZNP ), Li _1.2 Zr _1.9 Ca _0.1 (PO ₄ ) ₃ (LZCP), Li _7-x La ₃ Zr _2-x Nb _x O ₁₂ (LLZN), Li _7-x La ₃ Zr _{2− x Ta x O 12 (LLZT)} , Li 3x La 2 / 3x Ti 1 / 3x O 3 (LLT), Li 6 BaLa 2 Ta 2 O 12 (LBLT), Li 3 BO 3, Li 3 PO 4 A lithium ion conductor such as _-x Ni _x (LiPON), LiS-P ₂ S ₅ (LPS), or Li ₁₀ GeP ₂ S ₁₂ (LGPS) can be employed.

  (3) The solid electrolyte layer is preferably composed only of the above-described solid electrolyte having lithium ion conductivity. However, the solid electrolyte layer may contain a material other than the solid electrolyte in a range of less than 50% by volume. Can be adopted.

  In addition, as materials other than the solid electrolyte contained in the solid electrolyte layer, for example, a material having electrical insulation (that is, electrical insulation related to electron conductivity and ion conductivity) such as barium titanate (BT) can be employed. Examples of the material having electrical insulation include metal oxides such as strontium titanate, alumina, zirconia, and silica, and resins such as polyethylene, polypropylene, ABS, acrylic, epoxy, and polyimide.

Furthermore, oxides of elements constituting the solid electrolyte can be employed as materials other than the solid electrolyte contained in the solid electrolyte body. Examples of the oxide material of the element constituting the solid electrolyte include AlPO ₄ , TiO ₂ , LaTiO _{3 and the} like.

  As a method of forming the solid electrolyte layer, a sheet (green sheet) is prepared using the slurry containing the above-described solid electrolyte material, and the green sheet is fired under a predetermined condition, so that the solid electrolyte layer (accordingly) Various known methods such as a method of forming a laminate can be employed.

  (4) As a material for the internal electrode layer and the external electrode, various known conductive materials such as Au, Pt, Pd, Ag, Ni, and Cu can be adopted. As a method for forming this electrode layer, various known methods such as a screen printing method using a slurry or paste containing the conductive material can be employed. For example, a thin film method, a coating method, a thermal spraying method, a sputtering method, a plating method, or the like can be adopted.

DESCRIPTION OF SYMBOLS 1, 31, 41 ... Capacitor 3, 5, 7, 45, 47 ... Solid electrolyte layer 9, 11, 35, 49, 51, 53 ... Internal electrode layer 13, 15 ... External electrode 17, 33, 43 ... Base | substrate 19 ... 1st main surface 21 ... 2nd main surface 23 ... Side surface

Claims (3)

A solid electrolyte layer mainly composed of a solid electrolyte having lithium ion conductivity and an internal electrode layer are alternately laminated, and the solid electrolyte layer is disposed on at least one surface side and the other surface side in the lamination direction. A substrate,
A first external electrode and a second external electrode respectively formed on the solid electrolyte layer on one surface side and the other surface side of the substrate;
A capacitor comprising:
The internal electrode layer is an independent float electrode that is electrically separated from the external electrodes, and the area of the internal electrode layer disposed along the one or other surface of the base is the surface A capacitor characterized by being 95% or more of the area.   The capacitor according to claim 1, wherein the base has a plurality of the float electrodes.   The capacitor according to claim 1, wherein the float electrode is exposed on a side surface between the one surface and the other surface.

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