Electrochemical device and method for producing same

Abstract

This electrochemical device comprises: an electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a bottomed cylindrical case for accommodating the electrode group; and a gasket for sealing an opening portion of the cylindrical case. The gasket has a tubular shape with a through-hole, and at least one bottom surface of the tubular shape is continuous with an outer circumferential side surface of the tubular shape via a tapered surface which is inclined with respect to the outer circumferential side surface. One part of the gasket along the outer peripheral side surface is compressed by means of diametrical contraction of a portion of an outer circumference of the cylindrical case, thereby forming a compressed portion. At least a partial region of the tapered surface is a rough surface having a surface roughness that is greater than that of the outer peripheral side surface in the compressed portion.

Description

[Technical field]

[0001] The present disclosure relates to electrochemical devices and methods for making the same. [Background technology]

[0002] As an example of the configuration of an electrochemical device typified by a nonaqueous electrolyte battery, Patent Document 1 describes a slim lithium battery in which a negative electrode current collector wrapped with lithium and a separator and an organic electrolyte are inserted and injected into a positive electrode case containing a cylindrical positive electrode active material, and a gasket is inserted into the opening of the case, the battery having a hole in the center that is 0.1 to 0.3 mm smaller than the outer diameter of the current collector, an outer diameter that is 0.1 to 0.3 mm smaller than the inner diameter of the case, and the opening is sealed with a cylindrical gasket that has rubber elasticity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 02-12156 Summary of the Invention

[0004] The cylindrical gasket shown in Patent Document 1 is manufactured, for example, by molding a sheet in which a plurality of gaskets arranged two-dimensionally and connecting parts continuous with each of the plurality of gaskets are integrally formed, for example, by compression molding. The formed sheet is punched out and the gaskets are separated from the connecting parts, so that the plurality of gaskets in the sheet are separated into individual pieces. For example, the connecting parts located around the outer peripheral side surface of the cylindrical gasket are thinned. The thinned connecting parts are pulled and broken by punching, and the gaskets are separated from the sheet.

[0005] At this time, a fractured portion is formed on the outer peripheral side surface of the cylindrical gasket due to tension. This fractured portion is rougher than other portions, and a protruding portion protruding from the outer peripheral side surface may be formed as a burr on the fractured portion. This fractured portion may interfere with the inner side surface of the case when the gasket is inserted into the opening of the case, making it difficult to insert the gasket at the desired position or causing variation in the insertion position of the gasket. As a result, the productivity of the electrochemical device decreases. In addition, the sealing performance of the gasket may decrease, and the reliability of the electrochemical device may decrease.

[0006] An electrochemical device according to one aspect of the present disclosure includes an electrode group having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, a bottomed cylindrical case having an opening and accommodating the electrode group, and a gasket for sealing the opening of the cylindrical case. The gasket is cylindrical with a through hole extending along an axis, and has an outer peripheral side extending in an axial direction along the axis, a first bottom surface connected to one end of the outer peripheral side surface and opening at one end of the through hole, and a second bottom surface connected to the other end of the outer peripheral side surface and opening at the other end of the through hole. The first bottom surface of the cylindrical shape is continuous with the outer peripheral side surface of the cylindrical shape via a tapered surface that is inclined relative to the outer peripheral side surface. A portion of the gasket along the outer peripheral side surface is compressed by reducing the diameter of a part of the outer periphery of the cylindrical case to form a compressed portion. At least a portion of the tapered surface is a rough surface having a surface roughness greater than that of the outer peripheral side surface in the compressed portion.

[0007] In a method for producing an electrochemical device according to another aspect of the present disclosure, a gasket is obtained that is cylindrical and has a through hole, and a bottom surface where one end of the through hole of the cylindrical shape is open is continuous with an outer peripheral side surface of the cylindrical shape via a tapered surface that is inclined with respect to the outer peripheral side surface. A cylindrical case having an opening and a bottom is prepared. With an electrode group having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and an electrolyte contained in the cylindrical case, the gasket is inserted into the opening of the cylindrical case so that the bottom surface of the gasket faces the electrode group, and the opening of the cylindrical case is sealed. In the step of obtaining the gasket, a molded sheet is prepared that has a connecting portion having a surface that is continuous with the bottom surface, and in which a plurality of gaskets including the gasket are arranged one-dimensionally or two-dimensionally so as to be connected via the connecting portion. The connecting portion is broken so that a fracture surface inclined with respect to the outer peripheral side surface is formed, and the gasket is separated from the molded sheet.

[0008] According to the present disclosure, it is possible to realize a highly reliable electrochemical device that has excellent productivity and sealing performance when sealing with a gasket. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view and a bottom view illustrating a schematic example of a configuration of a gasket used in an electrochemical device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates an example of a molded sheet for producing the gasket illustrated in FIG. [Diagram 3] FIG. 3 is a side view illustrating another example of the configuration of a gasket used in an electrochemical device according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a partially cross-sectional front view of an electrochemical device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An electrochemical device according to one embodiment of the present disclosure comprises an electrode group having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, a bottomed cylindrical case that houses the electrode group, and a gasket that seals an opening of the cylindrical case.

[0011] In the present disclosure, the electrochemical device is a concept that includes batteries such as lithium ion secondary batteries and lithium primary batteries, and capacitors such as lithium ion capacitors and electric double layer capacitors. The positive and negative electrodes of the electrochemical device may be polarized electrodes or non-polarized electrodes. The positive and / or negative electrodes may be polarized electrodes that develop capacity by forming an electric double layer due to the adsorption of ions to the active material. Alternatively, the positive and / or negative electrodes may be non-polarized electrodes that develop capacity by the progress of a Faraday reaction in which lithium ions are reversibly absorbed and released. The electrochemical device may develop capacity by the absorption and / or release of lithium ions, or may develop capacity by the absorption and desorption of lithium ions to and from the active material or by chemical interaction.

[0012] The gasket has a cylindrical shape with a through hole extending along an axis, and has an outer peripheral side surface and two bottom surfaces opposed to each other via the outer peripheral side surface and a tapered surface. A first bottom surface on one side of the cylindrical shape is continuous with the outer peripheral side surface of the cylindrical shape via a tapered surface that is inclined with respect to the outer peripheral side surface.

[0013] A portion of the gasket along the outer peripheral side surface is compressed by reducing the diameter of a portion of the outer periphery of the cylindrical case to form a compressed portion. The repulsive force of the gasket at the compressed portion ensures sealing between the gasket and the cylindrical case.

[0014] At least a part of the tapered surface is a rough surface having a surface roughness greater than that of the outer peripheral side surface of the compressed portion. The area of ​​the tapered surface that is rougher than the outer peripheral side surface includes, for example, a fracture surface formed by cutting a molded sheet in which a plurality of gaskets are arranged one-dimensionally or two-dimensionally into individual pieces by, for example, a punching process. In the molded sheet, for example, the fracture surface is formed by applying a tensile stress to a connecting portion that connects a plurality of gaskets to break the sheet. The fracture surface may be formed in the tapered surface by cutting the connecting portion.

[0015] Like the first bottom surface of one of the cylindrical shapes, the second bottom surface of the other may be continuous with the outer peripheral side surface of the cylindrical shape via a second tapered surface inclined relative to the outer peripheral side surface. The first bottom surface of one side and / or the second bottom surface of the other side may be provided with an annular protruding portion extending to surround the through hole and / or an uneven surface. The functions of these second tapered surface, protruding portion, and uneven surface will be described later.

[0016] In the electrochemical device according to an embodiment of the present disclosure, a fracture surface is formed on the tapered surface of the gasket, so that when the gasket is inserted into the opening of the cylindrical case to seal the cylindrical case, the fracture surface is prevented from interfering with the inner surface of the case. This makes it easy to seal the cylindrical case with the gasket, and dramatically improves productivity. In addition, since the gasket can be inserted and fixed at a desired position with high precision, the sealing performance of the gasket can be maintained at a high level, and the reliability of the electrochemical device can be maintained at a high level.

[0017] Fig. 1 is a diagram showing a schematic example of a configuration of a gasket 13 used in an electrochemical device according to an embodiment of the present disclosure. The side view of Fig. 1 is a diagram seen from the side direction of the gasket 13, and the bottom view of Fig. 1 is a diagram seen from one bottom surface 13a of the gasket 13 (a bottom surface having a tapered surface 13d).

[0018] The gasket 13 shown in Fig. 1 is cylindrical and has a through hole 13h extending along an axis 13p in the center. The through hole 13h is closed by a current collecting rod 14 (see Fig. 4). The current collecting rod functions as an external terminal by being inserted into the through hole 13h with one end exposed to the outside. The axis 13p extends in an axial direction D13.

[0019] The gasket 13 has cylindrical bottom surfaces 13a and 13b and an outer peripheral side surface 13c connecting the bottom surfaces 13a and 13b. The bottom surface 13a is continuous with the outer peripheral side surface 13c via a tapered surface 13d. At least a part of the region 13X of the tapered surface 13d is a fracture surface 13k formed by breaking the gasket from a molded sheet, and has a surface roughness (arithmetic mean roughness) larger than that of the outer peripheral side surface 13c in the compressed portion 13f that contacts the reduced diameter portion 35 (see FIG. 4). The bottom surface 13a is connected to one end 13ca of the outer peripheral side surface 13c in the axial direction D13, and one end 13ha of the through hole 13h opens. The bottom surface 13b is connected to the other end 13cb of the outer peripheral side surface 13c in the axial direction D13, and the other end 13hb of the through hole 13h opens.

[0020] In addition, an annular protruding portion 131 extending so as to surround the through hole 13h is provided on the bottom surface 13b of the gasket 13. In Fig. 1, the outer peripheral surface of the annular protruding portion 131 is tapered with respect to the bottom surface 13b, but the outer peripheral surface of the protruding portion 131 may be configured so as to be perpendicular to the bottom surface 13b.

[0021] Fig. 2 is a cross-sectional view showing a schematic example of a molded sheet 100 before the gaskets 13 shown in Fig. 1 are divided into individual pieces. In Fig. 2, the molded sheet 100 has a structure in which a plurality of gaskets 13 are connected one-dimensionally or two-dimensionally via connecting parts 102, and the plurality of gaskets 13 and the connecting parts 102 together form a single sheet. The molded sheet 100 is manufactured by, for example, compression molding.

[0022] The connecting portion 102 is in the form of a plate or film having two main surfaces 102a, 102b opposite to each other. However, the connecting portion 102 does not need to completely fill the space between the gaskets 13, and an area (e.g., a through hole) that is not filled by either the gaskets 13 or the connecting portion 102 may be formed in the molded sheet 100.

[0023] One main surface 102a of the connecting portion 102 is continuous with the bottom surface 13a of the gasket 13. The other main surface 102b of the connecting portion 102 is continuous with the end of the bottom surface 13a side of the outer peripheral side surface 13c of the gasket 13. By separating the gasket 13 from the connecting portion of such a molded sheet 100, a cross section inclined with respect to the bottom surface 13a and the outer peripheral side surface 13c is formed, and a tapered surface 13d is formed.

[0024] For example, by applying force to molded sheet 100 from bottom surface 13a in a direction perpendicular to bottom surface 13a, connecting portion 102 is subjected to tensile stress and breaks, and gasket 13 is punched out from molded sheet 100, and gasket 13 is separated. At this time, by punching out so as to form fracture surface 13k inclined with respect to bottom surface 13a and outer peripheral side surface 13c, gasket 13 having a cross section is obtained in part of tapered surface 13d.

[0025] The surface roughness (arithmetic mean roughness) Ra of the outer peripheral side surface 13c of the compressed portion 13f that contacts the reduced diameter portion 35 (see FIG. 4) is, for example, 0.006 mm or less. In contrast, the surface roughness (arithmetic mean roughness) Ra of the tapered surface 13d that is the fracture surface 13k may be, for example, more than 0.006 mm, and may be 0.009 mm or more, or 0.015 mm or more.

[0026] The direction from one bottom surface 13a of the cylindrical shape to the other bottom surface 13b is the axial direction D13 along the axis 13p. The maximum height of the tapered surface 13d in the axial direction D13 based on one bottom surface 13a of the cylindrical shape is h1. The height from the end 13cb of the outer peripheral side surface 13c on the other bottom surface 13b side in the axial direction D13 based on one bottom surface 13a of the cylinder is h2. The ratio h1 / h2 of the height h1 to the height h2 may be in the range of 0.04 to 0.43. If the ratio h1 / h2 is 0.04 or more, the connecting portion 102 in the molded sheet 100 can be made sufficiently thick, and the molded sheet 100 can be easily peeled off from the mold for molding, improving productivity. On the other hand, if the ratio h1 / h2 is 0.43 or less, the tapered surface of the gasket does not overlap with the reduced diameter portion of the cylindrical case 11, and it is easy to maintain stable sealing. When a second tapered surface, which will be described later, is formed between the bottom surface 13b and the outer peripheral side surface 13c, the height h2 takes into consideration the height of the second tapered surface.

[0027] The ratio h2 / R of the height h2 to the outer diameter (diameter) R of the outer peripheral side surface 13c may be 0.18 or more and 1.6 or less, or 0.23 or more and 1.6 or less. The smaller the ratio h2 / R, the smaller the thickness of the gasket (height in the axial direction D13) is relative to the outer diameter R, and the smaller the volume occupied by the gasket in the cylindrical case 11 becomes, so that it is easier to realize a high capacity by increasing the amount of electrolyte to be filled and the amount of electrode active material. On the other hand, the larger the ratio h2 / R, the more the sealing performance of the gasket can be improved, and it is easier to obtain a high sealing pressure resistance, thereby improving the reliability of the electrochemical device. When the ratio h2 / R is in the range of 0.18 or more and 1.6 or less, it is easy to achieve both a high capacity and high reliability due to the high sealing performance of the gasket.

[0028] During use of the electrochemical device, the pressure inside the cylindrical case may increase. If the gasket bulges to a certain extent due to an increase in internal pressure, the repulsive force applied from the gasket to the inner surface of the cylindrical case may decrease, and the sealing performance may decrease. For this reason, it is preferable that the gasket has a structure capable of suppressing bulging due to an increase in internal pressure, or is made of a material capable of suppressing bulging. In general, from the viewpoint of suppressing bulging of the gasket due to an increase in internal pressure, the larger the ratio h2 / R, the better.

[0029] In addition, the larger the ratio h2 / R, the wider the tolerance for the height position of the tapered portion, improving product productivity. By making the gasket have a ratio h2 / R of 1.6 or less, it is possible to obtain sufficient deformation resistance against internal pressure under normal use conditions.

[0030] For example, when a rubber material is used for the gasket, a stable sealing repulsive force is obtained and the sealing performance is improved by using a rubber material such as butyl rubber for the gasket. On the other hand, rubber materials are easily deformed when the internal pressure increases. When the ratio h2 / R is less than 0.23, if a rubber material with a Young's modulus of about 0.05 GPa or less is used, the rigidity may be insufficient from the viewpoint of suppressing bulging. In this case, the gasket may have a laminated structure having at least two layers, a rubber material layer (e.g., a butyl rubber layer) and a fluororesin layer. This improves the rigidity of the gasket, and it is possible to achieve both a high sealing repulsive force and suppression of bulging of the gasket. The Young's modulus of the fluororesin may be 0.4 GPa or more as a general value.

[0031] More specifically, for example, when considering an electrochemical device with a cylindrical case having an outer diameter of 6.4 mm, a gasket with a height h2 of 1.2 mm, an outer diameter R of 6.6 mm (unloaded state), and a ratio h2 / R of 0.18 can be used. In this case, the height of the fluororesin layer is, for example, 0.7 mm, and the height of the rubber material layer is, for example, 0.5 mm, and the height of the gasket can be thinned to less than 1.5 mm, so that the internal volume of the electrochemical device can be increased, and the amount of electrolyte and the amount of electrode active material enclosed in the case can be increased compared to the conventional configuration. Therefore, it is possible to provide an electrochemical device with a higher capacity and higher reliability. In addition, the void in the case excluding the amount of electrolyte and the amount of electrode active material can be increased, so that the reflow resistance can be improved and the characteristics can be maintained for a longer period of time.

[0032] The outer diameter of the gasket may be larger than the outer diameter (diameter) of the cylindrical case. In this case, the gasket is press-fitted into the cylindrical case, improving the adhesion between the outer surface of the fluororesin layer of the gasket and the inner surface of the case. In addition, the adhesion between the rubber material layer having the same diameter as the fluororesin layer and the inner surface of the case is also improved, which prevents the electrolyte from leaking out from the gap between the inner surface of the case and the outer surface of the gasket when the gasket is inserted into the case, thereby improving productivity. In addition, the amount of reduction in diameter when forming a reduced diameter portion in the cylindrical case can be reduced.

[0033] When the gasket has a laminated structure having at least two layers, a rubber material layer and a fluororesin layer, the tapered surface 13d is formed in the rubber material layer, and the compressed portion 13f that comes into contact with the reduced diameter portion 35 (see FIG. 4) of the cylindrical case is formed in the rubber material layer.

[0034] When the ratio h2 / R is 0.23 or more, even if the gasket 13 is made of a rubber material alone, it can maintain its deformation resistance against internal pressure, and a highly reliable electrochemical device can be provided with less expensive gasket components.

[0035] Taper angle θ of tapered surface 13d 1For example, θ is equal to or greater than 4.6° and less than 90°. 1 When the angle θ between the tapered surface 13d and the outer peripheral side surface 13c (axial direction D13) is 4.6° or more, the burrs formed on the fractured surface 13k protrude beyond the outer peripheral side surface 13c, and the burrs are sufficiently prevented from interfering with the inner surface of the case when the gasket is inserted into the opening of the cylindrical case. 2 may be, for example, 2.3° or more and 45° or less.

[0036] 1, an annular protruding portion 131 extending to surround the through hole 13h is provided on the bottom surface 13b of the gasket 13. The protruding portion 131 is provided on the bottom surface of the gasket 13 on the side not facing the electrode group (i.e., the bottom surface opposite the tapered surface 13d across the outer circumferential side surface 13c), and serves to suppress the occurrence of leakage current between the current collecting rod blocking the through hole 13h and the cylindrical case through water droplets or the like adhering to the bottom surface.

[0037] In the electrochemical device, the gasket 23 is locally compressed by providing a reduced diameter portion 35 to a part of the outer periphery of the cylindrical case 11, and the opening of the cylindrical case 11 is sealed. In addition, a curled portion 31 is formed at the end of the opening side of the cylindrical case 11 (see FIG. 4). At this time, if the bottom surface 13b on the side not facing the electrode group is flat, a step is formed between the bottom surface 13b and the curled portion 31 formed along the bottom surface 13b, and a recess 13t may be formed in the bottom surface 13b. If water droplets or the like adhere to this recess 13t, the current collector rod end 32 and the curled portion 31 of the cylindrical case 11 may be short-circuited through the water droplets or the like, causing a leakage current to flow. By forming the protruding portion 131 on the bottom surface 13b, even when a curled portion is formed at the end of the opening side of the cylindrical case 11, current leakage through water droplets or the like between the current collector rod end 32 and the curled portion 31 of the cylindrical case 11 can be suppressed.

[0038] The outer diameter of the protruding surface of the annular protruding portion 131 is, for example, 0.39 to 0.86 times the outer diameter R of the outer peripheral side surface 13c. When the outer diameter of the protruding surface is 0.39 times or more of R, the thickness of the protruding portion 131 in the radial direction can be sufficiently ensured, and molding is easy. When the outer diameter of the protruding surface is 0.86 times or less of R, the gasket position can be well maintained against the internal pressure of the cylindrical case during normal use, and high sealing reliability can be achieved.

[0039] The protruding portion 131 suppresses current leakage between the current collecting rod end 32 and the curled portion 31 of the cylindrical case 11. Therefore, by extending the curled portion 31 inward toward the outer peripheral side surface of the protruding portion 131, the opening ratio obtained by dividing the inner diameter of the curled portion tip by the outer diameter of the case can be reduced. This makes it possible to suppress the intrusion of moisture from the outside, and improve the long-term reliability of the electrochemical device. It also makes it possible to suppress swelling of the gasket on the opening surface of the case of the product during reflow.

[0040] More specifically, for example, when the outer diameter R of the outer peripheral side surface 13c is 3.6 mm and the inner diameter of the through hole 13h is 1 mm, the radial thickness of the protruding portion 131 is preferably 0.2 mm or more, since this makes it easy to mold the gasket and maintain high productivity. Therefore, in this case, the outer diameter (diameter) of the protruding surface of the protruding portion 131 is preferably 1.4 mm or more, and is preferably 0.39 times or more the outer diameter R of the outer peripheral side surface 13c. In this case, compared to the conventional configuration in which the inner diameter of the tip of the curled portion is 2.6 mm and the case outer diameter is 4.5 mm, the inner diameter of the tip of the curled portion can be reduced to 1.5 mm, and the opening ratio can be reduced by 40% or more.

[0041] The outer peripheral side surface of the annular protruding portion 131 may be perpendicular to the bottom surface 13b, but it is more preferable to make the outer diameter of the protruding surface of the protruding portion 131 smaller than the outer diameter of the bottom surface 13b side of the protruding portion 131 in a tapered shape as shown in Fig. 1. In this case, the molded sheet 100 shown in Fig. 2 is formed by compression molding, and releasability is improved when the molded sheet 100 is removed from the mold, improving the productivity of the gasket and making it possible to provide a more inexpensive electrochemical device.

[0042] At least one of the bottom surfaces of the cylindrical gasket may be formed with an uneven surface or a matte finish. In the bottom view and bottom view of FIG. 1, a concentric uneven surface 132 is formed on the bottom surface 13a of the gasket 13 with the through hole 13h as the center. The gasket 13 is usually adhesive. The uneven surface 132 reduces the contact area and suppresses the sticking of the gaskets 13 to each other even when the gaskets 13 are put into a feeder for sealing a cylindrical case and come into contact with each other in the feeder. This makes it easier to handle the gasket and dramatically improves productivity.

[0043] The uneven surface 132 may be formed on the bottom surface 13b. In the case where the protruding portion 131 is provided on the bottom surface 13b, the protruding surface of the protruding portion 131 may be the uneven surface 132.

[0044] Furthermore, uneven surface 132 can function to limit the breaking position where tapered surface 13d is formed by punching molded sheet 100 to the position of the recessed portion of uneven surface 132. In this case, tapered surface 13d is formed so as to be continuous with the recessed portion of uneven surface 132. By adopting this shape configuration, the roundness of the outer peripheral shape of bottom surface 13a can be further improved.

[0045] The gasket 23 may be located at a position where the height of the center of gravity from the bottom surface 13a in the axial direction D13 is in the range of 0.45·H to 0.498·H, relative to the maximum distance H between one bottom surface 13a and the other bottom surface 13b of the gasket 13. In this case, by applying vibration of a specific frequency, a difference in the amplitude induced between the bottom surface 13a and the bottom surface 13b occurs, so that it is possible to control the gaskets so that they face in the same direction (for example, the bottom surface 13b is upward) during transportation, thereby dramatically improving productivity. More preferably, the gasket 23 is located at a position where the height of the center of gravity from the bottom surface 13a is in the range of 0.46·H to 0.49·H.

[0046] In this disclosure, the maximum distance H, maximum height h1 and height h2 of the gasket 23 are dimensions of the gasket 23 in an unloaded state when the gasket is removed from the electrochemical device and not inserted into the cylindrical case 11.

[0047] When protruding portion 131 is provided on bottom surface 13b and / or uneven surface 132 is provided on bottom surface 13a, maximum distance H is the height taking into consideration protruding portion 131 and uneven surface 132. In other words, maximum distance H is the maximum height of gasket 13 from a reference surface when gasket 13 is placed on the reference surface with bottom surface 13a facing down.

[0048] Furthermore, when the protruding portion 131 is provided on the bottom surface 13a, the above-mentioned maximum height h1 and height h2 are obtained by subtracting the height of the protruding portion 131 from the maximum height of the tapered surface 13d from the reference surface when the gasket 13 is placed on the reference surface with the bottom surface 13a facing down, and from the height of the outer peripheral side surface 13c from the reference surface (when the gasket has a second tapered surface 13e, the height of the second tapered surface 13e from the reference surface). Height h2 means the distance from one bottom surface 13a to the other bottom surface 13b.

[0049] By providing tapered surface 13d, gasket 13 usually has its center of gravity shifted toward bottom surface 13b. In order to position the center of gravity of the gasket at 0.45·H to 0.498·H from bottom surface 13a, for example, protruding portion 131 is provided on bottom surface 13b. Gasket 13 may have a multilayer structure in which multiple materials are laminated in axial direction D13 of gasket 13, and a layer of a higher density material among the multiple materials may be disposed on bottom surface 13a.

[0050] In the gasket 13, in addition to the tapered surface 13d provided on the side of the bottom surface 13a, another tapered surface may be provided on the bottom surface 13b. That is, the other bottom surface of the cylindrical gasket may be continuous with the cylindrical outer peripheral side surface via a second tapered surface inclined with respect to the outer peripheral side surface. The second tapered surface is formed at an arbitrary inclination angle depending on the mold used during molding. Therefore, the surface roughness of the second tapered surface is equivalent to the surface roughness of the outer peripheral side surface at the reduced diameter portion.

[0051] 3 is a schematic side view showing an example of a gasket 23 provided with a second tapered surface 13e that is continuous with the bottom surface 13b and the outer peripheral side surface 13c. In the example of FIG. 3, the gasket 23 is provided with annular protruding parts 131 that extend to surround the through-hole 13h on both the bottom surface 13a and the bottom surface 13b. The protruding surface of the protruding part 131 may be provided with an uneven surface or a matte finish. The angle that the second tapered surface 13e forms with the outer peripheral side surface 13c is the angle θ that the tapered surface 13d forms with the outer peripheral side surface 13c. 2 The heights of the two protruding portions 131 provided on the bottom surfaces 13a and 13b are also approximately the same. As a result, the overall shape of the gasket 13 is symmetrical with respect to the plane 13s perpendicular to the axis 13p of the cylindrical shape (except for the difference in surface roughness between the tapered surface 13d and the second tapered surface 13e).

[0052] In this case, when the gasket 23 is transported to the open end of the cylindrical case 11, it is not necessary to align the orientation of the gasket 23. For example, in FIG. 3, the gasket 23 may be transported with the bottom surface 13a facing upward, or with the bottom surface 13b facing upward. The gasket 23 may be inserted into the cylindrical case 11 so that the bottom surface 13a faces the electrode group, or the gasket 23 may be inserted into the cylindrical case so that the bottom surface 13b faces the electrode group. In either case, the gasket can be accurately inserted and fixed to the open end of the cylindrical case, and similar sealing performance can be obtained, thereby improving productivity.

[0053] The structure of the electrochemical device may be a configuration including a wound electrode group formed by spirally winding a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween, or a configuration including a single-layer or laminated electrode group formed by laminating a strip-shaped positive electrode and a strip-shaped negative electrode with a separator interposed therebetween. When the configuration of the present disclosure is applied to a cylindrical electrochemical device, the ratio of the outer diameter to the height does not matter.

[0054] One of the positive electrode or the negative electrode in the electrode group is electrically connected to a current collector bar, which is a current collector having a bar or rod shape. The current collector bar closes the through hole of the gasket, and one end of the current collector bar is exposed to the outside. The end of the current collector bar exposed to the outside functions as an external terminal. The other of the positive electrode or the negative electrode in the electrode group may be electrically connected to the cylindrical case. In this case, one of the current collector bar and the cylindrical case constitutes a positive electrode external terminal, and the other constitutes a negative electrode external terminal.

[0055] A plurality of (for example, two) through holes may be provided in the gasket. In this case, a plurality of current collecting rods are provided in the same number as the through holes. Each of the plurality of current collecting rods closes the corresponding through hole of the gasket, and one end of the current collecting rod is exposed to the outside. Of the plurality of current collecting rods, one or more current collecting rods are electrically connected to one of the positive electrode or the negative electrode in the electrode group, and the other one or more current collecting rods are electrically connected to the other of the positive electrode or the negative electrode in the electrode group. In this case, of the plurality of current collecting rods, one or more current collecting rods electrically connected to the positive electrode constitute a positive electrode external terminal, and one or more current collecting rods electrically connected to the negative electrode constitute a positive electrode external terminal.

[0056] A method for manufacturing an electrochemical device according to an embodiment of the present disclosure includes the steps of (i) obtaining a gasket having a cylindrical shape with a through hole in the center, one of which has a first bottom surface that is continuous with the cylindrical outer circumferential side surface via a tapered surface that is inclined with respect to the outer circumferential side surface, (ii) preparing a cylindrical case with a bottom, and (iii) inserting the gasket into an opening of the cylindrical case so that the first bottom surface faces the electrode group and sealing the opening of the cylindrical case in a state in which an electrode group having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and an electrolyte are contained in the cylindrical case. The step (ii) of obtaining a gasket includes the steps of: preparing a molded sheet having a connecting portion having a surface that is continuous with the first bottom surface, and in which a plurality of the gaskets are arranged one-dimensionally or two-dimensionally so as to be connected via the connecting portion; and breaking the connecting portion so as to form a fracture surface 13k that is inclined with respect to the outer circumferential side surface, and separating the gasket from the molded sheet.

[0057] Below, each component of the electrochemical device according to one embodiment of the present disclosure will be described in detail using a cylindrical pin-type lithium primary battery as an example.

[0058] (positive electrode) The positive electrode may include a positive electrode mixture layer (positive electrode active material layer) and a positive electrode current collector that holds the positive electrode mixture layer. The positive electrode mixture layer includes a positive electrode active material, and further includes a conductive agent, a binder, and the like, as necessary. The positive electrode current collector is, for example, a metal foil, and is formed into a strip shape suitable for winding. The material of the positive electrode current collector is not limited to this, but may include aluminum, an aluminum alloy, and the like.

[0059] The positive electrode current collector may include an expanded metal. In this case, the positive electrode can be obtained by, for example, pressing a wet positive electrode mixture prepared by adding a positive electrode active material, additives such as a conductive material and a binder, and an appropriate amount of water in a thickness direction so as to fill the mesh of the expanded metal, and then drying the mixture.

[0060] The positive electrode active material contained in the positive electrode includes manganese dioxide. A positive electrode containing manganese dioxide exhibits a relatively high voltage and has excellent pulse discharge characteristics. The manganese dioxide may be in a mixed crystal state containing a plurality of crystal states. The positive electrode may contain manganese oxides other than manganese dioxide. Examples of manganese oxides other than manganese dioxide include MnO, Mn 3 O 4 , Mn 2 O 3 , Mn 2 O 7 The main component of the manganese oxide contained in the positive electrode is preferably manganese dioxide.

[0061] A part of the manganese dioxide contained in the positive electrode may be doped with lithium. If the amount of lithium doped is small, a high capacity can be ensured. Manganese dioxide and manganese dioxide doped with a small amount of lithium are LixMnO 2 (0≦x≦0.05). The average composition of the manganese oxides contained in the positive electrode is LixMnO 2(0≦x≦0.05). The Li ratio x should be 0.05 or less in the initial discharge state of the lithium primary battery. The Li ratio x generally increases as the discharge of the lithium primary battery progresses. Theoretically, the oxidation number of manganese contained in manganese dioxide is 4. However, if other manganese oxides are contained in the positive electrode or if lithium is doped into manganese dioxide, the oxidation number of manganese may be reduced from 4. For this reason, LixMnO 2 In this case, the average oxidation state of manganese is allowed to be slightly lower than 4.

[0062] The positive electrode may contain other positive electrode active materials used in lithium primary batteries. Examples of other positive electrode active materials include graphite fluoride. The percentage of LixMnO in the overall positive electrode active material is 2 The proportion may be 90% by mass or more.

[0063] As the manganese dioxide, electrolytic manganese dioxide is preferably used. If necessary, electrolytic manganese dioxide that has been subjected to at least one of neutralization, washing, and calcination may be used. Electrolytic manganese dioxide is generally obtained by electrolysis of an aqueous manganese sulfate solution.

[0064] The positive electrode may be made of another positive electrode active material used in lithium primary batteries. For example, when the positive electrode is made of graphite fluoride, it is possible to maintain performance at higher temperatures, thereby realizing a lithium primary battery with excellent long-term reliability.

[0065] Examples of the binder include fluororesin, rubber particles, and acrylic resin.

[0066] The conductive agent may be, for example, a conductive carbon material, such as natural graphite, artificial graphite, carbon black, or carbon fiber.

[0067] (Negative electrode) The negative electrode may contain metallic lithium or a lithium alloy, or may contain both metallic lithium and a lithium alloy. For example, a composite containing metallic lithium and a lithium alloy may be used in the negative electrode.

[0068] Examples of the lithium alloy include a Li-Al alloy, a Li-Sn alloy, a Li-Ni-Si alloy, a Li-Pb alloy, etc. The content of metal elements other than lithium contained in the lithium alloy is preferably 0.05 to 15 mass % from the viewpoints of ensuring discharge capacity and stabilizing internal resistance.

[0069] The metallic lithium, the lithium alloy, or a composite thereof may be formed into any shape and thickness depending on the shape, dimensions, performance specifications, etc. of the lithium primary battery.

[0070] A sheet of metallic lithium, a lithium alloy, or a composite thereof may be used for the negative electrode. The sheet is obtained, for example, by extrusion. More specifically, in a cylindrical battery, a foil of metallic lithium or a lithium alloy having a shape having a longitudinal direction and a transverse direction is used.

[0071] In the case of a cylindrical battery, a long tape having a resin base material and an adhesive layer may be attached to at least one main surface of the negative electrode along the longitudinal direction. The main surface means the surface facing the positive electrode. The width of this tape is preferably 0.5 mm or more and 3 mm or less. This tape serves to prevent the negative electrode from being cut and causing current collection failure when the lithium component of the negative electrode is consumed by a reaction at the end of discharge.

[0072] Examples of materials that can be used for the resin substrate include fluororesins, polyimides, polyphenylene sulfide, polyethersulfone, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, etc. Among these, polyolefins are preferred, and polypropylene is more preferred.

[0073] The adhesive layer includes at least one component selected from the group consisting of, for example, a rubber component, a silicone component, and an acrylic resin component. Specifically, the rubber component may be synthetic rubber, natural rubber, or the like. Examples of synthetic rubber include butyl rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, neoprene, polyisobutylene, acrylonitrile-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butadiene block copolymer. Examples of silicone components include organic compounds having a polysiloxane structure, silicone-based polymers, and the like. Examples of silicone-based polymers include peroxide-curing silicone, addition reaction silicone, and the like. As the acrylic resin component, a polymer containing an acrylic monomer such as acrylic acid, methacrylic acid, an acrylic acid ester, or a methacrylic acid ester can be used, and examples thereof include homopolymers or copolymers of acrylic monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. The adhesive layer may contain a crosslinking agent, a plasticizer, and a tackifier.

[0074] (electrolyte) The electrolyte (nonaqueous electrolyte) may be, for example, a nonaqueous electrolytic solution in which lithium salt or lithium ions are dissolved in a nonaqueous solvent.

[0075] (Non-aqueous solvent) The non-aqueous solvent may be an organic solvent that can be generally used in non-aqueous electrolytes for lithium primary batteries. The non-aqueous solvent may be an ether, an ester, a carbonate ester, or the like. The non-aqueous solvent may be dimethyl ether, γ-butyl lactone, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, or the like. The non-aqueous electrolyte may contain one type of non-aqueous solvent, or may contain two or more types of non-aqueous solvents.

[0076] From the viewpoint of improving the discharge characteristics of the lithium primary battery, the non-aqueous solvent preferably contains a cyclic carbonate having a high boiling point and a chain ether having a low viscosity even at low temperatures. The cyclic carbonate preferably contains at least one selected from the group consisting of propylene carbonate (PC) and ethylene carbonate (EC), and PC is particularly preferred. The chain ether preferably has a viscosity of 1 mPa·s or less at 25°C, and particularly preferably contains dimethoxyethane (DME). The viscosity of the non-aqueous solvent is measured at 25°C at a shear rate of 10,000 (1 / s) using a microsample viscometer m-VROC manufactured by Rheosens.

[0077] The form of the electrolyte is not limited to a liquid, but may be a gel or a solid (polymer solid electrolyte).

[0078] (Lithium salts) The non-aqueous electrolyte may contain a lithium salt other than the cyclic imide component. Examples of the lithium salt include lithium salts used as solutes in lithium primary batteries. Examples of such lithium salts include LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiClO 4 , LiBF 4 , LiPF 6 , LiRaSO 3 (Ra is a fluoroalkyl group with 1 to 4 carbon atoms), LiFSO 3 , LiN(SO 2 Rb)(SO 2 Rc) (Rb and Rc are each independently a fluoroalkyl group having 1 to 4 carbon atoms), LiN(FSO 2 ) 2 , LiPO 2 F 2 , LiB(C 2 O 4 ) 2 , LiBF 2 (C 2 O 4The non-aqueous electrolyte may contain one or more of these lithium salts.

[0079] The concentration of lithium ions contained in the electrolyte (total concentration of lithium salts) is, for example, 0.2 to 2.0 mol / L, and may be 0.3 to 1.5 mol / L.

[0080] The electrolyte may contain additives as necessary. Examples of such additives include propane sultone, vinylene carbonate, etc. The total concentration of such additives contained in the non-aqueous electrolyte is, for example, 0.003 to 5 mol / L.

[0081] (Separator) A lithium primary battery usually includes a separator interposed between a positive electrode and a negative electrode. As the separator, a porous sheet formed of an insulating material having resistance to the internal environment of a lithium primary battery may be used. Specifically, a synthetic resin nonwoven fabric, a synthetic resin microporous film, or a laminate thereof may be used.

[0082] Examples of synthetic resins used for nonwoven fabrics include polypropylene, polyphenylene sulfide, polybutylene terephthalate, etc. Examples of synthetic resins used for microporous membranes include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, etc. The microporous membrane may contain inorganic particles as necessary.

[0083] The thickness of the separator is, for example, 5 μm to 100 μm The separator may be a single layer film made of one material, or a composite film or multilayer film made of two or more materials.

[0084] (gasket) The material of the gasket is not particularly limited, and may be appropriately selected in consideration of the stability against the electrolyte, heat resistance, etc. Specifically, polypropylene, polyethylene, polyphenylene sulfide, polyether ketone, polyamide, polyimide, liquid crystal polymer, copolymer of perfluoroalkoxyethylene, etc. may be used. These may be used alone or in a mixture of two or more kinds, and may also be used in combination with a filler such as inorganic fiber.

[0085] The gasket may include, for example, a rubber material. The gasket may be composed of a single layer of a rubber material layer containing the rubber material, or may have a multi-layer structure of a rubber material layer and a fluororesin layer. As the rubber material, butyl rubber (isobutylene-isoprene copolymer) (IIR) is preferable. Butyl rubber can obtain stable elasticity by peroxide crosslinking or resin crosslinking, and can obtain a stable sealing repulsive force. Butyl rubber has low gas permeability and high insulating properties compared to other rubber materials, so that the performance of the electrochemical device can be maintained high even during long-term storage.

[0086] The material of the fluororesin layer is preferably PTFE (polytetrafluoroethane), PVDF (polyvinylidene fluoride), PFA (perfluoroalkoxyalkane), ETFE (ethylene-tetrafluoroethylene copolymer), or FEP (perfluoroethylene-propene copolymer).When forming a multilayer structure of a butyl rubber layer and a fluororesin layer, in order to improve the adhesion at the interface with the rubber material layer, it is preferable to roughen the surface of the fluororesin layer on the butyl rubber layer side by corona treatment, plasma treatment, sodium treatment, application of an organic solvent containing active sodium dissolved therein, or the like, and perform compression molding in a state where the adhesion with the butyl rubber layer is improved.

[0087] Compression molding is performed on a single layer of butyl rubber only, or on a multi-layer of fluororesin and butyl rubber. A portion of the molded sheet is punched out to obtain individual pieces of the gasket, and at the same time, a tapered surface can be formed on part of the butyl rubber layer during the punching operation. A configuration in which a fracture surface 13k of the butyl rubber layer is formed on part of the tapered surface allows for a gasket to be obtained with higher productivity.

[0088] (Current collector rod) Examples of materials for the current collector rod include copper, aluminum, stainless steel, iron, nickel, palladium, gold, silver, platinum, etc. These may be used alone or as an alloy containing two or more kinds.

[0089] The outer diameter of the current collecting rod can be appropriately set in consideration of the size of the battery, the strength of the current collecting rod, workability, etc. The outer diameter of the current collecting rod at the portion inserted into the through hole of the gasket may be, for example, 0.5 to 50 mm, or 0.5 to 10 mm. In particular, when the battery is a small battery such as a pin-type battery, the outer diameter of the current collecting rod at the portion inserted into the through hole of the gasket may be 1 to 6 mm, or 1 to 4 mm.

[0090] (Cylindrical case) Examples of the material for the cylindrical case include silver, copper, iron, nickel, palladium, gold, platinum, aluminum, stainless steel, etc. The thickness of the cylindrical case can be appropriately set, but may be 50 to 500 μm or 100 to 300 μm in consideration of strength and processability.

[0091] Fig. 4 shows a front view of a cylindrical lithium primary battery according to an embodiment of the present disclosure, with a portion of the battery in cross section. In Fig. 4, the lithium primary battery 10 includes a cylindrical case 11, a wound electrode group 12 housed in the case 11, and a gasket 13 that seals the case 11. The wound electrode group 12 includes a current collector 14, a negative electrode 15, a positive electrode 16, and a separator 17 that separates the negative electrode 15 and the positive electrode 16. A non-aqueous electrolyte is in contact with the wound electrode group 12.

[0092] The current collecting rod 14 is electrically connected to the negative electrode 15 at the winding start position (innermost circumference) of the wound electrode group 12. One end of the current collecting rod 14 is inserted into a through hole 13h of the gasket 13. The opening side end of the cylindrical case 11 is sealed by forming a reduced diameter portion 35, whereby the opening of the cylindrical case 11 is sealed by the gasket 13. One end of the current collecting rod 14, that is, a current collecting rod end portion 32, is exposed to the outside of the cylindrical case 11 and is used as an external negative electrode terminal of the lithium primary battery 10.

[0093] A positive electrode 16 is wound around the outermost circumference of the wound electrode group 12. A positive electrode current collector (not shown) is exposed at this outermost positive electrode 16, and the positive electrode current collector is in contact with the inner circumferential surface of the cylindrical case 11 so as to apply pressure thereto. This electrically connects the cylindrical case 11 and the positive electrode 16. An insulating cover 34 is provided on the outer surface of the cylindrical case 11, and the portion not provided with the insulating cover 34 is used as an external positive electrode terminal of the lithium primary battery 10. An insulating cap 33 is provided at the other end of the current collecting rod 14 to prevent a short circuit from occurring between the cylindrical case 11 and the current collecting rod 14. [Industrial Applicability]

[0094] The electrochemical device of the present disclosure maintains high sealing performance even after long-term use, and therefore can be suitably used, for example, as the main power source for various meters or a memory backup power source. [Explanation of symbols]

[0095] 10 Pin-type lithium primary battery (electrochemical device) 11 Cylindrical case 12 winding electrode group 13,23 Gasket 13a Bottom surface (1st bottom surface) 13b Bottom surface (second bottom surface) 13c Outer side 13d Tapered surface 13e Second tapered surface 13f Compression section 13h through hole 13k fracture surface 13p axis 131 Protruding part 132 Uneven surface 14 Current collector rod 15 negative electrode 16 positive electrode 17 Separator 31 Curl Section 32 Collector rod end 33 Insulating cap 34 Insulating cover 35 Reduced diameter part 100 Molded Sheet 102 Connection part

Claims

1. an electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a cylindrical case having an opening and a bottom that houses the electrode group; a gasket that seals an opening of the cylindrical case; Equipped with The gasket is tubular and has a through hole extending along an axis, and has an outer peripheral side surface extending in an axial direction along the axis, a first bottom surface connected to one end of the outer peripheral side surface and at which one end of the through hole opens, and a second bottom surface connected to the other end of the outer peripheral side surface and at which the other end of the through hole opens, The first bottom surface of the cylindrical shape is continuous with the outer peripheral side surface of the cylindrical shape via a first tapered surface that is inclined with respect to the outer peripheral side surface, a portion of the gasket along the outer circumferential side surface is compressed by reducing a diameter of a part of the outer circumferential surface of the cylindrical case to form a compressed portion, An electrochemical device, wherein at least a portion of the first tapered surface is a rough surface having a surface roughness greater than that of the outer peripheral side surface of the compressed portion.

2. the first tapered surface has a fracture surface of the gasket; The electrochemical device of claim 1 , wherein the roughened surface of the first tapered surface includes the fractured surface.

3. 2. The electrochemical device according to claim 1, wherein a ratio h1 / h2 of a maximum height h1 of the first tapered surface in the axial direction, based on the first bottom surface of the cylindrical shape, to a height h2 of the other end of the outer peripheral side surface in the axial direction, based on the first bottom surface of the cylindrical shape, is in the range of 0.04 to 0.

43.

4. 2. The electrochemical device according to claim 1, wherein a ratio h2 / R of a height h2 of the other end of the outer peripheral side surface in the axial direction, based on the first bottom surface of the cylindrical shape, to an outer diameter R of the outer peripheral side surface is 0.18 or more and 1.6 or less.

5. 2. The electrochemical device according to claim 1, wherein the gasket has an annular protruding portion provided on one of the first and second bottom surfaces of the cylindrical shape that does not face the electrode group and extending to surround the through hole.

6. The electrochemical device according to claim 1 , wherein at least one of the first bottom surface and the second bottom surface of the cylindrical gasket is formed with an uneven surface or a matte finish.

7. The uneven surface is formed on at least one of the first bottom surface and the second bottom surface of the cylindrical gasket, The electrochemical device according to claim 6 , wherein the first tapered surface is continuous with a concave portion of the uneven surface.

8. 2. The electrochemical device according to claim 1, wherein a height of a center of gravity of the gasket in the axial direction from the first bottom surface is in a range of 0.45·H to 0.498·H, with respect to a maximum distance H between the first bottom surface and the second bottom surface of the cylindrical shape of the gasket.

9. The electrochemical device according to any one of claims 1 to 8, wherein the second bottom surface of the cylindrical gasket is continuous with the other end of the outer peripheral side surface via a second tapered surface that is inclined relative to the outer peripheral side surface.

10. The electrochemical device of claim 9 , wherein the overall shape of the gasket is symmetrical with respect to a plane perpendicular to the axis.

11. 9. The electrochemical device according to claim 1, wherein the gasket comprises butyl rubber or a laminated structure of a butyl rubber layer and a fluororesin layer.

12. obtaining a gasket having a cylindrical shape with a through hole, the bottom surface of the cylindrical shape at which one end of the through hole is open being continuous with an outer peripheral side surface of the cylindrical shape via a tapered surface that is inclined with respect to the outer peripheral side surface; preparing a cylindrical case having an opening and a bottom; a step of inserting the gasket into the opening of the cylindrical case such that the bottom surface of the gasket faces the electrode group, and sealing the opening of the cylindrical case, in a state in which an electrode group having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and an electrolyte are contained in the cylindrical case; Including, the step of sealing the opening of the cylindrical case includes a step of compressing a portion of an outer periphery of the cylindrical case by reducing a diameter of the outer periphery of the cylindrical case, the portion being along an outer periphery of the gasket inserted into the opening of the cylindrical case, to form a compressed portion; The step of obtaining the gasket comprises: A step of preparing a molded sheet having a connecting portion having a surface continuous with the bottom surface, the molding sheet including the gasket being arranged one-dimensionally or two-dimensionally so as to be connected via the connecting portion; A step of breaking the connecting portion to form a fracture surface inclined with respect to the outer peripheral side surface, and separating the gasket from the molded sheet; Including, A method for manufacturing an electrochemical device, wherein the surface roughness of the fractured surface is greater than that of the outer peripheral side surface of the gasket in the compressed portion.

Images