JP2008010780A - Electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical element capable of improving a yield. <P>SOLUTION: The electrochemical element includes an accommodating container 2 having a recessed shape, a pair of electrodes comprising positive poles 1a, and negative poles 1b sequentially disposed on an internal bottom of the accommodating container 2; a separator 8 interposed between a pair of the electrodes; and a sealing plate 9 disposed on an upper surface of the accommodating container 2. Protrusions 4a, 4b protruded towards the positive poles 1a and the separator 8 at least at two inner sides of the accommodating container 2 are provided, and the negative poles 1b are fixed between the upper surfaces of the protrusions 4a, 4b and the sealing plate 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a storage container having a concave shape, a pair of electrodes disposed on the inner bottom surface of the storage container, a separator interposed between the pair of electrodes, and a sealing plate disposed on the top surface of the storage container. The present invention relates to an electrochemical element provided.

  Conventionally, an electric double layer capacitor is known as one of electrochemical elements. The electric double layer capacitor is used as a small-capacity, large-capacity capacitor for a backup power source, an auxiliary power source, etc. of a cellular phone or a household electric product, and is expected to have high performance.

  The electric double layer capacitor is soldered and mounted on a printed circuit board of various electronic devices. The conventional electric double layer capacitor has a round shape such as a coin type or a button type, and requires attachment of a terminal to be soldered to the board, and the exclusive area when mounted is large. For this reason, an electric double layer capacitor including a concave container using ceramic, resin, or the like and a sealing plate having a metal portion is disclosed. As a result, the terminal attachment process and the mounting area can be reduced.

Furthermore, a rectangular parallelepiped recess is formed in the center of the upper surface, a ceramic base having a step formed between the inner surface and the bottom of the recess, a negative electrode wiring formed on the upper surface of the step, and the bottom of the recess A positive electrode disposed on the bottom surface of the recess, a separator disposed on the positive electrode, and a negative electrode disposed on the separator, a part of the negative electrode serving as the negative electrode wiring An electric double layer capacitor in contact has been proposed (see Patent Document 1).
Japanese Patent Laying-Open No. 2005-11780 (FIG. 4)

  However, in the structure of the electric double layer capacitor disclosed in Patent Document 1, current is collected from the negative electrode by contact between the negative electrode wiring formed on the upper surface of the step and the negative electrode. There was a problem that contact failure due to, and an internal short circuit occurred between the positive electrode and the negative electrode, resulting in a decrease in yield.

  In view of the above problems, an object of the present invention is to provide an electrochemical device capable of improving yield.

  In order to achieve the above object, the first feature of the present invention is that a storage container having a concave shape, a pair of electrodes composed of a lower electrode and an upper electrode arranged in order on the inner bottom surface of the storage container, An electrochemical element comprising a separator interposed between the electrodes and a sealing plate disposed on the upper surface of the storage container, and projects toward at least two inner surfaces of the storage container toward the lower electrode and the separator The gist is that the upper electrode is an electrochemical element that is provided between the upper surface of the protrusion and the sealing plate.

  According to this feature, the at least two inner surfaces of the storage container are provided with a protruding portion protruding toward the lower electrode and the separator, and the upper electrode is fixed between the upper surface of the protruding portion and the sealing plate. In addition, it is possible to suppress the displacement of the upper electrode and to improve the yield.

  The gist of the second feature of the present invention is that the electrochemical device according to the first feature further includes a wiring disposed on the upper surface of the protruding portion and in contact with the upper electrode.

  According to this feature, since the wiring further disposed on the upper surface of the protruding portion and in contact with the upper electrode, the contact area between the wiring and the upper electrode can be increased. As a result, the internal resistance of the electrochemical device can be reduced, and even if the upper electrode is misaligned, contact failure and internal short circuit can be suppressed, and the yield can be improved.

  According to a third aspect of the present invention, in the electrochemical device according to the first or second aspect, the projecting portion has two inner side faces of the storage container, three inner side faces of the storage container, or 4 of the storage container. The gist is that the separator is provided between the two inner surfaces and is fixed by being sandwiched between the protrusions.

  According to this feature, the protrusions are provided on the two inner surfaces facing the storage container, the three inner surfaces of the storage container, or the four inner surfaces of the storage container, and the separator is fixed by being sandwiched between the protrusions. Therefore, it is possible to prevent the displacement of the separators and improve the yield.

  A fourth feature of the present invention is the electrochemical device according to any one of the first to third features, further comprising a current collector made of a conductive material and disposed between the upper electrode and the separator. Is the gist.

  According to this feature, a current collector made of a conductive material, which is disposed between the upper electrode and the separator, is further provided, so that it is possible to efficiently collect current from the upper electrode, and the inside of the electrochemical device. Resistance can be reduced.

  The fifth feature of the present invention is summarized in that, in the electrochemical device according to the fourth feature, the current collector is made of a punched metal made of SUS.

  According to this feature, since the current collector is made of punched metal made of SUS, it is possible to collect current more efficiently from the upper electrode.

  A sixth feature of the present invention is the electrochemical device according to any one of the first to fifth features, wherein the thickness of the upper electrode is relative to the thickness between the upper surface of the protruding portion and the lower surface of the sealing plate. The gist is 1.0 to 1.05 times.

  According to this feature, the thickness of the upper electrode is 1.0 to 1.05 times the thickness between the upper surface of the protruding portion and the lower surface of the sealing plate. Can be suppressed. In addition, when the wiring is arranged on the upper surface of the protruding portion, the contact between the upper electrode and the wiring can be maintained well due to the increase in the component pressure, and the internal resistance of the electrochemical element can be reduced. .

  According to a seventh feature of the present invention, in the electrochemical device according to any one of the first to sixth features, the thickness of the lower electrode is 0. 0 relative to the thickness between the inner bottom surface and the upper surface of the protruding portion. The gist is that it is 95 to 1.0 times.

  According to this feature, by preventing the height of the lower electrode from exceeding the height of the protruding portion, it is possible to suppress the displacement of the separator and to prevent the occurrence of an internal short circuit.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochemical element which can improve a yield can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  In the following embodiments, an electric double layer capacitor including a storage container having a concave shape will be described as an example of an electrochemical element.

  As shown in FIG. 1, the electric double layer capacitor includes a storage container 2 having a concave shape, and a positive electrode (lower electrode) 1 a and a negative electrode (upper electrode) 1 b arranged in order on the inner bottom surface of the storage container 2. A pair of electrodes 1a, 1b, a separator 8 interposed between the pair of electrodes 1a, 1b, an electrolyte 10 impregnated in the pair of electrodes 1a, 1b and the separator 8, and a seal disposed on the upper surface of the storage container 2 And a plate 9. Projecting portions 4 a and 4 b projecting toward the positive electrode 1 a and the separator 8 are provided on at least two inner surfaces of the storage container 2, and the negative electrode 1 b is fixed between the upper surfaces of the projecting portions 4 a and 4 b and the sealing plate 9. Is done.

  In the example of FIG. 1, the protrusions 4 a and 4 b are provided on the two inner surfaces facing the storage container 2, but on the three inner surfaces of the storage container 2 or the four inner surfaces of the storage container 2. It may be provided. The separator 8 is fixed by being sandwiched between the protrusions 4a and 4b.

  The storage container 2 has a rectangular planar shape, and has a rectangular opening on the upper surface. The rectangular opening is sealed by a sealing plate 9. A current collector 7 is disposed on the inner bottom surface of the storage container 2, and a negative electrode wiring 5 b in contact with the negative electrode 1 b is disposed on the upper surfaces of the projecting portions 4 a and 4 b. For example, the negative electrode wiring 5b is disposed along the outer periphery of the storage container 2 as shown in FIG. Further, the negative electrode wiring 5 b extends through the wall surface of the storage container 2 and extends to the outer bottom surface of the storage container 2.

  The current collector 7 is electrically connected to the positive electrode wiring 5 a through the extraction electrode 6. As shown in FIG. 1 and FIG. 2B, the positive electrode wiring 5 a penetrates the wall surface of the storage container 2 and extends to the outer bottom surface of the storage container 2.

  The storage container 2 is made of at least one of resin, glass, ceramics, ceramic glass, or metal. Since these are excellent in heat resistance, an electric double layer capacitor constituted by using these is excellent in reflow soldering resistance and long-term storage stability.

  The sealing plate 9 is made of a metal material such as nickel, copper, brass, zinc, tin, gold, platinum, stainless steel (SUS444, SUS239J4L, SUS317J4L, etc.), tungsten, aluminum, Kovar, or a heat resistant resin, like the container 2. It is made of a heat resistant material such as glass, ceramics or ceramic glass. The seal ring 3 is made of a metal material such as nickel, gold, and kovar.

  The positive electrode 1a and the negative electrode 1b are produced by extracting sheet-like activated carbon made of activated carbon fiber or activated carbon powder with a punching die. The electrode material can be used as long as it is electrochemically inactive and has a large specific surface area, but it is preferable to mainly use activated carbon powder having a large specific surface area. In addition to the activated carbon powder, materials having a large specific surface area such as carbon black, metal fine particles, and conductive metal oxide fine particles can be preferably used.

  The current collector 7 may be any material having excellent conductivity and electrochemical durability, such as valve metals such as aluminum, titanium, and tantalum, noble metals such as stainless steel, gold, and platinum, graphite, and glassy carbon. Carbon-based materials such as conductive rubber containing carbon black can be preferably used.

As the separator 8, an insulating film or cloth having a high ion permeability and a predetermined mechanical strength is used. In reflow soldering, glass fibers can be used most stably, but resins such as polyphenylene sulfide, polyethylene terephthalate, polyamide, polyimide having a heat distortion temperature of 230 ° C. or higher can also be used. The hole diameter and thickness of the separator 8 are not particularly limited, and are design matters determined based on the current value of the device used and the internal resistance of the capacitor. A ceramic porous body can also be used.
The electrolytic solution 10 is an organic electrolytic solution. Here, the solvent used for the electrolytic solution 10 may be any solvent that can dissolve the electrolyte, and a known one that is generally used for an electrolytic solution of an electric double layer capacitor or a non-aqueous electrolyte secondary battery is used. be able to. For example, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, sulfolane, ethylene glycol, polyethylene glycol, vinylene carbonate, chloroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl Use carbonate, dimethoxymethane, dimethoxyethane, methoxyethoxyethane, diethoxyethane, tetrahydrofuran, 2-methyl-tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, acetonitrile, methyl formate, dioxolane, 4-methyl-1,3-dioxolane, etc. be able to.

Moreover, as electrolyte in said electrolyte solution 10, alkali metal salts, such as sodium salt and potassium salt, ammonium salt, etc. can be used. Here, as the above ammonium salt, for _{example, NH 4 ClO 4, NH 4} BF 4, NH 4 PF 6, NH 4 CF 3 SO 3, (NH 4) 2 B 10 Cl 10, (NH 4) 2 B ₁₂ Cl ₁₂ , NH ₄ N (CF ₃ SO ₂ ) ₂ , NH ₄ N (C ₂ F ₃ SO ₂ ) ₂ , NH ₄ N (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ), NH ₄ C ( CF ₃ SO ₂ ) ₃ or the like can be used. Examples of other electrolytes include (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NPF ₆ , (C ₂ H ₅ ) ₄ NCF ₃ SO ₃ , [(C ₂ H ₅ ) ₄ N] ₂ B ₁₀ Cl ₁₀ , [(C ₂ H ₅ ) ₄ N] ₂ B ₁₂ Cl ₁₂ , (C ₂ H ₅ ) ₄ N (CF ₃ SO ₂ ) ₂ , (C _{2 H 5) 4 N (C} 2 F 5 SO 2) 2, (C 2 H 5) 4 N (C 4 F 9 SO 2) (CF 3 SO 2), (C 2 H 5) 4 C (CF 3 SO ₂ ) ₃ or the like can be used.

(Function and effect)
The electric double layer capacitor according to this embodiment includes protrusions 4a and 4b protruding toward the positive electrode 1a and the separator 8 on at least two inner surfaces of the storage container 2, and the negative electrode 1b includes the protrusions 4a and 4b. Since it is fixed between the upper surface and the sealing plate 9, it is possible to suppress the displacement of the negative electrode 1b and improve the yield.

  In addition, since the negative electrode wiring 5b that is disposed on the upper surfaces of the protruding portions 4a and 4b and contacts the negative electrode 1b is provided, the contact area between the negative electrode 1b and the negative electrode wiring 5b can be increased. As a result, the internal resistance of the electric double layer capacitor cell can be reduced, and even if the negative electrode 1b is displaced, contact failure can be suppressed and the yield can be improved.

  Further, the protrusions 4a and 4b are provided on the two inner surfaces facing the storage container 2, the three inner surfaces of the storage container 2, or the four inner surfaces of the storage container 2, and the separator 8 is provided on the protrusions. Since it is sandwiched and fixed, the displacement of the separator 8 can be prevented, the occurrence of a short circuit between the positive electrode 1a and the negative electrode 1b can be suppressed, and the yield can be improved.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  The electrochemical element according to the above-described embodiment has been described using an electric double layer capacitor. However, the present invention is not limited to this, and the electrolytic solution 10 containing an electrolyte, the pair of electrodes 1a and 1b, the separator 8, and the insulation If it is an electrochemical element provided with the storage container 2 made of a conductive material, the same effect as the above-described embodiment can be expected. For example, the present invention can be similarly applied to a thin battery such as a lithium battery or a polyacene battery composed of a concave container and a sealing plate.

  In addition, an example in which the negative electrode wiring 5b is disposed on the upper surfaces of the protrusions 4a and 4b has been described. However, the present invention is not limited to this, and a current collector of the negative electrode 1b is provided on the lower surface of the sealing plate 9, 2 may be configured to be electrically connected to the negative electrode wiring 5b formed on the outer surface.

  Further, although an example in which the positive electrode 1a is the lower electrode and the negative electrode 1b is the lower electrode has been described, the positive electrode 1a may be disposed on the lower side and the negative electrode 1b may be disposed on the upper side.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  Hereinafter, the electric double layer capacitor according to the present invention will be specifically described with reference to examples, and by forming protrusions (steps) on at least two sides inside the storage container, the yield is improved and the internal resistance is increased. It will be clarified with a comparative example that the reduction is reduced. In addition, the electric double layer capacitor according to the present invention is not limited to those shown in the following examples, and can be appropriately changed and implemented without departing from the gist thereof.

(First embodiment)
In the first example, the positive electrode 1a, the negative electrode 1b, the electrolytic solution 10, and the storage container 2 were produced as follows, and an electric double layer capacitor as shown in FIG. 1 was produced.

[Production of electrodes]
To activated carbon powder having a specific surface area of 2000 m ² / g, 10 wt% acetylene black and 10 wt% polytetrafluoroethylene (PTFE) were added and kneaded to obtain a sheet having a thickness of 0.5 mm. The sheet thus obtained was punched into a 2.5 mm square to produce a positive electrode 1a, and a negative electrode 1b was produced by punching into a 2.5 mm long and 3.5 mm wide rectangle.

[Electrolyte adjustment]
Electrolyte solution 10 was prepared by using propylene carbonate as a solvent and dissolving (C ₂ H ₅ ) ₄ NBF ₄ as a solute at a concentration of 1 mol / l.

[Production of storage container]
The storage container 2 was an alumina container having an outer dimension of 5.0 mm on one side, a height of 1.25 mm, and an inner dimension of 4.0 mm. The seal ring 3 was provided at the upper end of the storage container 2, and the height from the inner bottom surface to the upper end of the seal ring 3 was 1.0 mm.

  Inside the storage container 2, protrusions 4 a and 4 b having a height of 0.5 mm from the inner bottom surface are provided on two opposing sides inside the storage container 2. On the upper surfaces of the protrusions 4a and 4b of the storage container 2, a nickel layer and a gold layer were sequentially deposited on the exposed surface of the negative electrode wiring 5b by a plating method.

  The lead electrode 6 was formed on the inner bottom surface of the storage container 2 by sequentially depositing a nickel layer and a gold layer on the exposed surface of the positive electrode wiring 5a by a plating method. A current collector 7 was formed on the upper surface of the extraction electrode 6 by depositing gold by sputtering so as to cover the extraction electrode 6.

[Production of electric double layer capacitor]
In the center of the inner bottom surface of the storage container 2 manufactured as described above, the positive electrode 1a manufactured as described above is fixed on the current collector 7 with a conductive paste, and the glass fiber separator 8 is connected to the positive electrode. The negative electrode 1b was placed on 1a so as to be in contact with the protrusions 4a and 4b provided on the two sides of the storage container 2.

  The storage container 2 in which the positive electrode 1a, the negative electrode 1b, and the separator 8 were installed was heated to 250 ° C. in a dry atmosphere having a dew point of −40 ° C. or less, and left for 15 minutes to dry the positive electrode 1a and the negative electrode 1b.

  Next, the electrolytic solution 10 prepared as described above was poured into the storage container 2 and then vacuum impregnated at 40 kPa for 30 seconds. Then, the sealing board 9 was arrange | positioned on the storage container 2, and it welded by the parallel seam welding, and obtained the electrical double layer capacitor.

(Second embodiment)
An electric double layer capacitor was fabricated in the same manner as in the first example, except that the protruding portion of the storage container 2 was provided on four sides (four inner side surfaces) and the negative electrode 1b was 3.5 mm square.

(Third embodiment)
An electric double layer capacitor was produced in the same manner as in the first example except that the thickness of the negative electrode 1b was changed to 0.53 mm.

(Fourth embodiment)
An electric double layer capacitor was produced in the same manner as in the first example except that the thickness of the negative electrode 1b was 0.47 mm.

(5th Example)
An electric double layer capacitor was produced in the same manner as in the first example except that the thickness of the positive electrode 1a was changed to 0.53 mm.

(Sixth embodiment)
An electric double layer capacitor was fabricated in the same manner as in the first example except that the thickness of the positive electrode 1a was 0.47 mm.

(Seventh embodiment)
As shown in FIG. 3, an electric double layer capacitor is formed in the same manner as in the first embodiment, except that a punching metal made of SUS316 is disposed between the negative electrode 1b and the separator 8 as the current collector 11 of the negative electrode 1b. Produced. As the punching metal, a metal having a diameter of 0.5 mmφ, an aperture ratio of 50%, and a thickness of 50 μm was used. The current collector 11 extends to the upper surfaces of the protrusions 4a and 4b, and the current collector 11 and the negative electrode wiring 5b are electrically connected on the protrusions 4a and 4b.

(Comparative example)
As shown in FIG. 4, an electric double layer capacitor was produced in the same manner as in the first example except that the protruding portion of the storage container 2 was only one side (one inner side surface).

(test)
Next, 20 cells of each of the electric double layer capacitors of the first to seventh examples and the comparative example were produced, and the internal resistance value was measured. The internal resistance value was measured with an ohm tester at 1 kHz between the positive and negative electrodes. Among the fabricated cells, there were defective cells that could not be charged. Table 1 shows the average value of the measurement results of the internal resistance value and the ratio of defective cells.

  As is apparent from the comparison between the first to seventh embodiments and the comparative example, the ratio of defective cells can be reduced and the internal resistance of the cells can be reduced by setting the protruding portions to two or four sides facing each other. Reduced. By adopting two or four sides that face each other, the structure is such that contact failure and internal short-circuiting are unlikely to occur even when the electrode arrangement is misaligned. Further, since the contact area between the negative electrode 1b and the negative electrode wiring 5b is increased, it is considered that the internal resistance is reduced.

  In comparison between the first example and the seventh example, the internal resistance of the cell was reduced in the seventh example in which the current collector 11 of the negative electrode 1b was arranged. This is considered because the current collecting property of the negative electrode 1b was improved.

  In the comparison between the first example, the third example, and the fourth example, in the fourth example in which the thickness of the negative electrode 1b is 0.47 mm, the internal resistance value of the cell is increased to 0.5 mm or more. In the first and third examples, lower internal resistance values were obtained. This is because the thickness of the negative electrode 1b is larger than the thickness between the upper surfaces of the protrusions 4a and 4b and the lower surface of the sealing plate 9, so that the constituent pressure increases, so that the negative electrode 1b and the negative electrode wiring 5b This is thought to be due to the reduction in contact resistance. In addition, although the structural pressure was increased by increasing the thickness of the negative electrode 1b, a similar effect can be obtained by forming a convex portion on the lower surface of the sealing plate 9.

  In comparison between the first example, the fifth example, and the sixth example, in the fifth example in which the thickness of the positive electrode 1a was 0.53 mm, the ratio of defective cells increased. This is because the thickness of the positive electrode 1a exceeds the height of the protrusions 4a and 4b, so that the disposition of the separator 8 occurs and a short circuit occurs between the positive electrode 1a and the negative electrode 1b. The thickness of the positive electrode 1a was able to be made into a lower defect rate in the 1st and 6th Example made into 0.5 mm or less.

  This time, an impregnation step of performing vacuum impregnation after the injection of the electrolytic solution 10 was adopted. In particular, in the second embodiment, since the opening of the concave portion constituted by the protruding portion is covered with the negative electrode 1b, the electrolytic solution 10 is hardly impregnated in the positive electrode 1a, and the above-described impregnation step is necessary. . However, this impregnation step can be omitted by applying the impregnation well. For example, when the projecting portion has two sides, three sides, or four sides, the size of the negative electrode 1b is adjusted so that the opening of the concave portion constituted by the projecting portion is not covered with the negative electrode 1b. Thus, the impregnation can be satisfactorily performed.

  The size of the electric double layer capacitor cell is not limited to the size described in this embodiment, and a larger size can be adopted.

It is sectional drawing of the electric double layer capacitor which concerns on embodiment of this invention. 2A is a top view showing a cross section between AA in FIG. 1, and FIG. 2B is a top view showing a cross section between BB in FIG. It is sectional drawing of the electric double layer capacitor which concerns on 7th Example of this invention. It is sectional drawing of the electric double layer capacitor which concerns on the comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a ... Positive electrode 1b ... Negative electrode 2 ... Storage container 3 ... Seal ring 4a, 4b ... Projection part 5a ... Positive electrode wiring 5b ... Negative electrode wiring 6 ... Extraction electrode 7 ... Current collector 8 ... Separator 9 ... Sealing plate 10 ... Electrolyte solution 11 ... current collector

Claims (7)

A storage container having a concave shape, a pair of electrodes composed of a lower electrode and an upper electrode arranged in order on the inner bottom surface of the storage container, a separator interposed between the pair of electrodes, and an upper surface of the storage container An electrochemical device comprising a sealing plate disposed,
Providing a projecting portion projecting toward the lower electrode and the separator on at least two inner side surfaces of the storage container,
The electrochemical device, wherein the upper electrode is fixed between an upper surface of the protruding portion and the sealing plate.   The electrochemical device according to claim 1, further comprising a wiring disposed on an upper surface of the protruding portion and in contact with the upper electrode. The protrusions are provided on two opposing inner surfaces of the storage container, three inner surfaces of the storage container, or four inner surfaces of the storage container,
The electrochemical device according to claim 1, wherein the separator is sandwiched and fixed between the protrusions.   The electrochemical element according to any one of claims 1 to 3, further comprising a current collector made of a conductive material, disposed between the upper electrode and the separator.   The electrochemical device according to claim 4, wherein the current collector is made of SUS punching metal.   The thickness of the upper electrode is 1.0 to 1.05 times as large as the thickness between the upper surface of the protruding portion and the lower surface of the sealing plate. 2. The electrochemical element according to item 1.   The thickness of the lower electrode is 0.95 to 1.0 times the thickness between the inner bottom surface and the upper surface of the protruding portion. The electrochemical element as described in.

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