Gaskets for electrochemical cells, and electrochemical cells

Abstract

To provide a gasket for an electrochemical cell that has excellent sealing properties and can form an electrochemical cell that has a large electric capacity and can be reflow-soldered.SOLUTION: A gasket 30 comprises: a base 31 that extends over the whole circumference in a circumferential direction and is arranged between a bottom of a positive electrode can and an opening edge of a negative electrode can; an outer wall part 41 that projects upward from an outer peripheral part of the base 31 and extends over the whole circumference along the circumferential direction, and is closely adhered to an inner peripheral surface of the positive electrode can and an outer peripheral surface of the negative electrode can; and an inner wall part 51 that projects upward from the base 31 on the inside of the outer wall part 41 and extends over the whole circumference along the circumferential direction. The inner peripheral surface of the outer wall part 41 includes a guide part 43 that extends in an axial direction with a fixed inner diameter, and a sealant holding part 44 that is located between the guide part 43 and the base 31 and can hold a sealant having fluidity. The outer peripheral surface of the outer wall part 41 includes a tapered part 56 that extends over the whole circumference in the circumferential direction. The tapered part 56 gradually increases its diameter from a lower part toward an upper part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a gasket for an electrochemical cell, and to an electrochemical cell. [Background technology]

[0002] Some electrochemical cell containers are sealed by crimping the openings of a pair of metal cans with a gasket sandwiched between them. Technologies have been developed to improve the sealing performance of this type of electrochemical cell in order to increase its reliability.

[0003] In recent years, small non-aqueous electrolyte secondary batteries, which are a type of electrochemical cell, are required to be compatible with reflow soldering in order to improve the efficiency of soldering when mounted on a circuit board. In reflow soldering, the internal pressure is likely to increase due to heating during mounting, so further improvement in sealing performance is required. For example, Patent Document 1 discloses a ring-shaped gasket for electrochemical cells having an outer wall and an inner wall, in which a plurality of ring-shaped protrusions that hold a sealant are formed on the inner surface of the outer wall. This gasket is said to have improved sealing performance compared to conventional gasket shapes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-216855 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, electrochemical cells that can be reflow soldered are required to have a large electric capacity without increasing the mounting area. If the electric capacity is increased by making the electrochemical cell thicker, the peripheral walls of the pair of metal cans will be enlarged in the height direction, and the pressure applied during crimping may be dispersed, making it difficult to ensure sufficient sealing.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS The present invention provides a gasket for an electrochemical cell that has excellent sealing properties and allows the formation of an electrochemical cell that is reflow solderable and has a large electric capacity, and an electrochemical cell equipped with the gasket. [Means for solving the problem]

[0007] The gasket for an electrochemical cell of the present invention is an annular gasket provided in an electrochemical cell having a bottomed cylindrical positive electrode can, and a topped cylindrical negative electrode can inserted inside the positive electrode can and forming an accommodation space between the positive electrode can and the topped cylindrical negative electrode can for accommodating a positive electrode and a negative electrode, the gasket having a base extending all around in a circumferential direction and disposed between a bottom of the positive electrode can and an opening edge of the negative electrode can, a first gasket protruding from an outer periphery of the base in a first direction in the axial direction of a central axis of the base and extending all around along the circumferential direction, and interposing between an inner circumferential surface of the positive electrode can and an outer periphery of the negative electrode can. the inner peripheral surface of the outer wall portion includes a guide portion extending in the axial direction with a constant inner diameter, and a sealant holding portion located between the guide portion and the base and capable of holding a flowable sealant; the outer peripheral surface of the outer wall portion includes a tapered portion extending around the entire circumferential direction, and the tapered portion gradually increases in diameter from the second axial direction to the first axial direction.

[0008] According to the present invention, by inserting the peripheral wall of the negative electrode can into the inside of the sealant holding part in which the sealant is held, the sealant is disposed between the sealant holding part and the peripheral wall of the negative electrode can, so that the sealability between the gasket and the negative electrode can is ensured. In addition, since a guide part extending in the axial direction with a constant inner diameter is formed on the opposite side of the base part, sandwiching the sealant holding part in the axial direction, when the negative electrode can is inserted inside the outer wall part, the peripheral wall part of the negative electrode can can be smoothly guided toward the sealant holding part. Furthermore, since the part between the inner circumferential surface of the outer wall part and the tapered part becomes thicker toward the tip side (first direction), the gasket with the negative electrode can attached is inserted into the positive electrode can, and the opening edge of the positive electrode can is narrowed by crimping, so that the thick part of the outer wall part of the gasket can be pressed against the negative electrode can to hold the negative electrode can in the second direction. In particular, when the peripheral wall of the negative electrode can has a double-cylinder structure in which the peripheral wall is folded back at the edge of the opening of the negative electrode can, the thick portion of the outer wall of the gasket can be pressed against the edge of the outer peripheral cylinder in the first direction to hold the negative electrode can in the second direction. Therefore, even in an electrochemical cell that has an increased thickness in order to increase the electric capacity, it is possible to prevent moisture from entering the inside through the opening of the positive electrode can along the surface of the gasket. Therefore, by using the gasket, an electrochemical cell that has excellent sealing properties and a large electric capacity and can be reflow soldered can be formed.

[0009] In the above-mentioned gasket for an electrochemical cell, the tapered portion may overlap at least the guide portion when viewed in a radial direction.

[0010] According to the present invention, the provision of the guide portion in the outer wall portion allows the portion extending with a constant inner diameter to be formed thick, thereby making it easier to attach the negative electrode can to the gasket and ensuring excellent sealing performance.

[0011] In the above-mentioned gasket for an electrochemical cell, the sealant holding portion may protrude radially inward from the guide portion, extend along the circumferential direction over the entire circumference, and include a plurality of protrusions provided in the axial direction.

[0012] According to the present invention, a groove is formed between adjacent convex portions in the axial direction, so that the sealant holding portion can easily hold the flowable sealant in the groove. Also, the groove between the convex portions extends all around in the circumferential direction, so that the sealant holding portion can hold the sealant all around. Furthermore, since the convex portions protrude radially inward beyond the guide portion, the outer wall portion can be reliably brought into contact with the outer peripheral surface of the negative electrode can. Therefore, by using the gasket, an electrochemical cell with excellent sealing properties can be formed.

[0013] In the above-mentioned gasket for an electrochemical cell, the first direction edge of the inner wall portion may be located in the second direction further than central positions in the axial direction of the first direction edge of the base portion and the first direction edge of the outer wall portion.

[0014] According to the present invention, the amount of displacement of the inner wall can be reduced when the base is pressurized by the negative electrode can pressed in the second direction, compared to a configuration in which the edge of the inner wall in the first direction is located further in the first direction than the center position. This can prevent the inner wall from exerting a load on the contents of the electrochemical cell. Therefore, the use of the gasket can prevent defects such as internal short circuits, resulting in a highly reliable electrochemical cell.

[0015] In the above-mentioned gasket for an electrochemical cell, a dimension of the base in the axial direction may be larger than maximum dimensions of each of the outer wall portion and the inner wall portion in a radial direction.

[0016] According to the present invention, it is possible to ensure the thickness of the outer wall, particularly in the portion close to the base. This ensures the strength of the gasket in an electrochemical cell that has an increased thickness due to an increase in electrical capacity. In addition, a sufficient amount of gasket is disposed between the bottom of the positive electrode can and the opening edge of the negative electrode can, so that the positive electrode can and the negative electrode can can be sufficiently tightly attached to the gasket during the crimping process of the positive electrode can. Therefore, by using the gasket, an electrochemical cell with excellent sealing properties can be formed.

[0017] The gasket for an electrochemical cell described above may further include a gate portion protruding radially inward from an inner circumferential surface of the base, wherein an outer surface of the gate portion has an inclined surface facing in a direction inclined toward the first direction relative to the radial direction, and the inclined surface extends in the first direction from the radial inside to the radial outside on a longitudinal cross section along the central axis.

[0018] According to the present invention, when the gasket is injection molded, the molten resin flows from the cavity corresponding to the gate portion of the mold into the cavity corresponding to the base portion. The molten resin that flows into the cavity corresponding to the base portion of the mold flows into the cavity corresponding to the inner wall portion. At this time, the inner surface of the mold corresponding to the inclined surface of the gate portion extends in the first axial direction, that is, in the direction from the base portion toward the inner wall portion, from the inside to the outside in the radial direction, so that the molten resin can be actively guided into the cavity corresponding to the inner wall portion of the mold. In particular, when the base portion is formed thick, the resin is likely to accumulate in the cavity corresponding to the base portion of the mold, so that the inner wall portion can be reliably formed by the above-mentioned action. Therefore, when the gasket is formed by injection molding, the occurrence of molding defects such as insufficient filling can be suppressed.

[0019] In the above-mentioned gasket for an electrochemical cell, the inner wall portion may be tapered in the first direction on the longitudinal cross section.

[0020] According to the present invention, it is possible to easily fill a cavity corresponding to an inner wall portion of a mold with molten resin to its deepest portion, and therefore, when forming a gasket by injection molding, it is possible to more reliably prevent molding defects such as insufficient filling.

[0021] The electrochemical cell of the present invention comprises the above-mentioned gasket for an electrochemical cell, the positive electrode can and the negative electrode can, wherein the positive electrode can has a bottom and a positive electrode can peripheral wall portion extending in the first direction from an outer peripheral edge of the bottom, and the negative electrode can has a top and a negative electrode can peripheral wall portion extending in the first direction from an outer peripheral edge of the top, and the negative electrode can peripheral wall portion is disposed between the outer wall portion and the inner wall portion and is in contact with the sealant holding portion over its entire circumference.

[0022] According to the present invention, since the above-mentioned gasket is provided, it is possible to provide an electrochemical cell which has excellent sealing properties and a large electric capacity and can be subjected to reflow soldering.

[0023] In the above electrochemical cell, the negative electrode can peripheral wall portion includes a double cylinder portion extending in the first direction from the opening edge of the negative electrode can toward the top, the double cylinder portion having an inner cylinder portion extending in the axial direction and an outer cylinder portion surrounding the inner cylinder portion from the outside in the radial direction, and the first direction edge of the inner wall portion may be located in the second direction further than the first direction edge of the outer cylinder portion.

[0024] According to the present invention, compared to a configuration in which the edge of the inner wall in the first direction is located further in the first direction than the edge of the outer tubular portion in the first direction, when the base is pressurized by the negative electrode can pressed in the second direction, the amount of displacement of the inner wall can be reduced. This makes it possible to prevent the inner wall from exerting a load on the contents of the electrochemical cell. This makes it possible to prevent the occurrence of defects such as internal short circuits. Therefore, it is possible to provide a highly reliable electrochemical cell. Effect of the Invention

[0025] According to the present invention, a reflow solderable electrochemical cell can be formed which has excellent sealing properties and high capacitance. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view of a battery according to an embodiment. [Diagram 2]FIG. 2 is a longitudinal cross-sectional view showing the battery according to the embodiment, illustrating the state before the exterior body is sealed. [Diagram 3] FIG. 2 is a longitudinal sectional view showing the gasket of the embodiment. [Figure 4] FIG. 2 is a vertical cross-sectional view showing the negative electrode can of the embodiment. [Diagram 5] FIG. 11 is a longitudinal sectional view showing a gasket according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, components having the same or similar functions are given the same reference numerals. Then, duplicated descriptions of those components may be omitted. The nonaqueous electrolyte secondary battery (electrochemical cell) of the embodiment is a secondary battery in which an active material used as a positive electrode or a negative electrode and a separator are housed in a container. In the following description, the nonaqueous electrolyte secondary battery is simply referred to as a battery.

[0028] FIG. 1 is a cross-sectional view of a battery according to an embodiment. As shown in FIG. 1, the battery 1 of the embodiment is a so-called coin (button) type battery. The battery 1 of the embodiment is a small coin type battery with an outer diameter of about 5 mm and a thickness of about 2 mm. However, the outer diameter of the battery 1 is not limited to these values. The battery 1 includes an exterior body 3 having a circular shape in a plan view, a positive electrode 5, a negative electrode 7, and a separator 9 disposed in the exterior body 3, and an electrolyte 11 filled in the exterior body 3. The exterior body 3 includes a positive electrode can 20 and a negative electrode can 60 attached to the positive electrode can 20 via an insulating gasket 30. Details of the exterior body 3 will be described later.

[0029] The positive electrode 5 and the negative electrode 7 are arranged facing each other with a separator 9 interposed therebetween. The positive electrode 5 is electrically connected to the inner surface of a positive electrode can 20 via a positive electrode current collector 13. The negative electrode 7 is electrically connected to the inner surface of a negative electrode can 60 via a negative electrode current collector 15. The positive electrode 5 may be directly connected to the positive electrode can 20 so that the positive electrode can 20 functions as a current collector. The negative electrode 7 may be directly connected to the negative electrode can 60 so that the negative electrode can 60 functions as a current collector. The positive electrode 5, the negative electrode 7, and the separator 9 are impregnated with the electrolyte 11 filled in the exterior body 3.

[0030] In the positive electrode 5, the type of the positive electrode active material is not particularly limited, but for example, it is preferable to use a material containing lithium manganese oxide as the positive electrode active material. The content of the positive electrode active material in the positive electrode 5 is determined in consideration of the discharge capacity required for the battery 1, and can be in the range of 50 to 95 mass %. If the content of the positive electrode active material is equal to or more than the lower limit of the above-mentioned preferable range, a sufficient discharge capacity is easily obtained, and if it is equal to or less than the upper limit of the preferable range, the positive electrode 5 is easily formed.

[0031] The positive electrode 5 may contain a conductive assistant (hereinafter, the conductive assistant used in the positive electrode 5 may be referred to as a "positive electrode conductive assistant"). Examples of the positive electrode conductive assistant include carbonaceous materials such as furnace black, ketjen black, acetylene black, and graphite. The positive electrode conductive assistant may be used alone or in combination of two or more of the above.

[0032] The positive electrode 5 may contain a binder (hereinafter, the binder used in the positive electrode 5 may be referred to as a "positive electrode binder"). For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), etc. may be selected as the positive electrode binder. In addition, the positive electrode binder may be one of the above alone or two or more of them may be used in combination. The content of the positive electrode binder in the positive electrode 5 may be, for example, 1 to 20 mass %. As the positive electrode current collector 13, a conductive resin adhesive containing carbon as a conductive filler, etc. may be used.

[0033] In addition, in this embodiment, the positive electrode active material may contain, in addition to the lithium manganese oxide, another positive electrode active material, for example, one or more of other oxides such as molybdenum oxide, lithium iron phosphate compound, lithium cobalt oxide, lithium nickel oxide, and vanadium oxide.

[0034] In the negative electrode 7, the type of the negative electrode active material is not particularly limited, but for example, it is preferable that the negative electrode active material contains silicon oxide. In addition, in the negative electrode 7, the negative electrode active material is preferably made of silicon oxide represented by SiOx (0≦x<2).

[0035] In addition, the negative electrode 7 may contain other negative electrode active materials in addition to the above SiOx (0≦x<2) as the negative electrode active material, for example, other negative electrode active materials such as Si and C. When granular SiOx (0≦x<2) is used as the negative electrode active material, the particle diameter (D50) thereof is not particularly limited, and may be selected, for example, from a range of 0.1 to 30 μm, or from a range of 1 to 10 μm. If the particle diameter (D50) of SiOx is less than the lower limit of the above range, for example, when the battery 1 is stored or used in a harsh high-temperature and high-humidity environment, or reactivity due to reflow treatment increases, the battery characteristics may be impaired, and if the particle diameter (D50) exceeds the upper limit, the discharge rate may be reduced.

[0036] The content of the negative electrode active material in the negative electrode 7, i.e., SiOx (0≦x<2), is determined in consideration of the discharge capacity required for the battery 1, and can be selected from a range of 50 mass % or more, and can be selected from a range of 60 to 80 mass %. In the negative electrode 7, if the content of the negative electrode active material made of the above elements is equal to or more than the lower limit of the above range, a sufficient discharge capacity is easily obtained, and if it is equal to or less than the upper limit, the negative electrode 7 is easily formed.

[0037] The negative electrode 7 may contain a conductive assistant (hereinafter, the conductive assistant used in the negative electrode 7 may be referred to as a "negative electrode conductive assistant"). The negative electrode conductive assistant is the same as the positive electrode conductive assistant.

[0038] The negative electrode 7 may contain a binder (hereinafter, the binder used in the negative electrode 7 may be referred to as the "negative electrode binder"). As the negative electrode binder, polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), polyamide-imide (PAI), or the like can be selected.

[0039] The negative electrode binder may be one of the above, or two or more of them may be used in combination. When polyacrylic acid is used as the negative electrode binder, the polyacrylic acid may be adjusted to a pH of 3 to 10 in advance. In this case, the pH can be adjusted by using, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide. The content of the negative electrode binder in the negative electrode 7 is, for example, in the range of 1 to 20 mass%.

[0040] The separator 9 is interposed between the positive electrode 5 and the negative electrode 7. In the battery 1 of this embodiment, a lithium body 17 such as lithium foil is provided between the negative electrode 7 and the separator 9. The separator 9 is an insulating film having a large ion permeability and mechanical strength. For example, the separator 9 may be made of glass such as alkali glass, borosilicate glass, quartz glass, lead glass, or a nonwoven fabric made of a resin such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyamide-imide (PAI), polyamide, or polyimide (PI). Among them, it is preferable to use a glass nonwoven fabric as the separator 9, and it is more preferable to use a borosilicate glass nonwoven fabric. The glass nonwoven fabric has excellent mechanical strength and a large ion permeability, and therefore can reduce the internal resistance and improve the discharge capacity. The thickness of the separator 9 is determined in consideration of the size of the battery 1, the material of the separator 9, and the like. The thickness of the separator 9 can be, for example, 5 to 300 μm.

[0041] The electrolyte 11 is usually a non-aqueous solvent in which a supporting salt is dissolved. The non-aqueous solvent of the electrolyte 11 of this embodiment contains tetraglyme (TEG) as a main solvent, diethoxyethane (DEE) as a sub-solvent, and further contains ethylene carbonate (EC) and vinylene carbonate (VC) as additives. The non-aqueous solvent is usually determined in consideration of the heat resistance and viscosity required for the electrolyte 11. In addition to tetraglyme, triglyme, penta-glyme, diglyme, etc. can be used as the main solvent for constituting the glyme-based solvent.

[0042] The electrolyte 11 of this embodiment uses a non-aqueous solvent containing ethylene carbonate (EC), tetraglyme (TEG), and diethoxyethane (DEE). By adopting such a configuration, DEE and TEG solvate the Li ions forming the supporting salt. At this time, since DEE has a higher donor number than TEG, DEE selectively solvates with the Li ions. In this way, DEE and TEG solvate the Li ions forming the supporting salt, and protect the Li ions. As a result, even if moisture penetrates into the inside of the non-aqueous electrolyte secondary battery under a high-temperature and high-humidity environment, it is possible to prevent moisture from reacting with Li, thereby suppressing a decrease in discharge capacity and improving storage characteristics.

[0043] The ratio of each of the above solvents in the nonaqueous solvent in the electrolytic solution 11 is not particularly limited, and may be selected from the following ranges: TEG: 30% by mass to 48.5% by mass, DEE: 30% by mass to 48.5% by mass, EC: 0.5% by mass to 10% by mass, VC: 2% by mass to 13% by mass (total 100%). When the ratios of TEG, DEE, and EC contained in the nonaqueous solvent are within the above ranges, the above-mentioned effect of protecting the Li ions by DEE solvating them can be obtained.

[0044] Even within the above range, the VC content is preferably in the range of 2.5% by mass to 10% by mass, more preferably in the range of 5.0% by mass to 7.5% by mass. The upper limit of the TEG and DEE contents is preferably 48.25% by mass or less, more preferably 48% by mass or less. When the VC content is in the range of 2% by mass to 13% by mass, the change in thickness of the exterior body 3 consisting of the positive electrode can 20 and the negative electrode can 60 is small even when heated during reflow soldering, and the increase in internal resistance can also be reduced. Furthermore, when the VC content is in the range of 2.5% by mass to 10.0% by mass, the change in thickness of the storage container 2 can be made smaller even when heated during reflow soldering, and the increase in internal resistance can also be made smaller. Even within these ranges, the VC content is most preferably in the range of 5.0% by mass to 7.5% by mass.

[0045] As a supporting salt, for example, LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiN(CF 3 SO 3 ) 2 , LiN(FSO 2 ) 2 Lithium salts of organic acids such as LiPF 6 , LiBF 4 , LiB(C 6 H 5 ) 4 Examples of the supporting salt include inorganic acid lithium salts such as LiCl and LiBr. Among them, it is preferable to use a lithium salt that is a compound having lithium ion conductivity as the supporting salt, and LiN(CF 3 SO 2 ) 2 , LiN(FSO 2 ) 2 , LiBF 4 It is particularly preferable to use LiN(CF) from the viewpoints of heat resistance, low reactivity with moisture, and sufficient storage properties. 3 SO 2 ) 2 The supporting salt is preferably one of the above-mentioned salts, or a combination of two or more of the above-mentioned salts may be used.

[0046] The content of the supporting salt in the electrolytic solution 11 can be determined taking into consideration the type of the supporting salt, etc. For example, the content of the supporting salt in the electrolytic solution 11 is preferably 0.1 to 3.5 mol / L, more preferably 0.5 to 3 mol / L, and particularly preferably 1 to 2.5 mol / L. If the concentration of the supporting salt in the electrolytic solution 11 is too high or too low, the electrical conductivity may decrease, which may adversely affect the battery characteristics.

[0047] The exterior body 3 will now be described in detail. The exterior body 3 includes a bottomed cylindrical positive electrode can 20, an annular gasket 30 fitted inside the positive electrode can 20, and a topped cylindrical negative electrode can 60 inserted into the opening of the positive electrode can 20 and assembled to the positive electrode can 20 via the gasket 30. The exterior body 3 forms a storage space between the positive electrode can 20 and the negative electrode can 60 to store the positive electrode 5 and the negative electrode 7. The positive electrode can 20 and the negative electrode can 60 are arranged at a distance from each other with the gasket 30 in between. The exterior body 3 is sealed by squeezing the opening edge 21 of the positive electrode can 20 by crimping, and pressing the gasket 30 against the outer peripheral surface of the negative electrode can 60. The positive electrode can 20, the negative electrode can 60, and the gasket 30 are arranged so that their respective central axes are located on a common axis. Hereinafter, this common axis will be referred to as axis O, the direction along axis O will be referred to as the axial direction, the direction perpendicular to axis O and extending radially from axis O will be referred to as the radial direction, and the direction going around axis O will be referred to as the circumferential direction. Additionally, within the axial direction, the direction toward the opening of positive electrode can 20 will be defined as "upward" (first direction), and the direction opposite to upward will be defined as "downward" (second direction). Additionally, a cross section along axis O will be referred to as a "longitudinal cross section."

[0048] Fig. 2 is a longitudinal sectional view showing the battery of the embodiment, illustrating the state before the exterior body is sealed. Note that in Fig. 2, the illustration of the contents such as the positive electrode 5 and the negative electrode 7 is omitted. As shown in Fig. 2, the positive electrode can 20 is formed in a cylindrical shape that opens upward. The positive electrode can 20 includes a disk-shaped bottom 22 and a positive electrode can peripheral wall 24 that extends upward from the outer periphery of the bottom 22 all around toward an opening edge 21 of the positive electrode can 20. The positive electrode can 20 is formed by drawing a stainless steel plate. For example, SUS316L, SUS329J4L, or the like can be used as the positive electrode can 20.

[0049] 3 is a vertical cross-sectional view showing the gasket of the embodiment, in which gasket 30 is shown alone before being attached to positive electrode can 20 and negative electrode can 60. As shown in FIG. 3 , the gasket 30 includes a base 31 extending circumferentially around the entire circumference, a gate portion 36 protruding radially inward from the inner surface of the base 31, an outer wall portion 41 extending upward around the entire circumference from the outer periphery of the base 31, and an inner wall portion 51 extending upward around the entire circumference from the inner periphery of the base 31 inside the outer wall portion 41.

[0050] Base 31 has bottom surface 32 facing downward, top surface 33 facing upward between outer wall 41 and inner wall 51, and inner circumferential surface 34 extending upward from the inner circumferential edge of bottom surface 32. The outer circumferential portion of bottom surface 32 is formed into a curved surface that protrudes downward and radially outward, following the inner shape of the boundary between bottom 22 and positive can peripheral wall 24 of positive can 20. The lower portion of inner circumferential surface 34 extends upward and radially inward from the inner circumferential edge of bottom surface 32. The upper portion of inner circumferential surface 34 extends upward in the axial direction from the upper end edge of the lower portion of inner circumferential surface 34.

[0051] The gate portion 36 is provided around the entire circumference in the circumferential direction. The gate portion 36 is formed on the boundary between the upper and lower parts of the inner circumferential surface 34. However, the gate portion 36 may be formed on one of the upper and lower parts of the inner circumferential surface 34. The outer surface of the gate portion 36 has an upper surface 37 (inclined surface) that faces in a direction inclined upward from the radial direction. The upper surface 37 is inclined with respect to the radial direction on a vertical cross section, and extends upward from the inner side to the outer side in the radial direction, connecting to the upper part of the inner circumferential surface 34. However, the upper surface 37 may be connected to the inner circumferential surface of the inner wall portion 51.

[0052] The outer wall portion 41 is formed in a cylindrical shape. The inner peripheral surface of the outer wall portion 41 includes a chamfered portion 42, a guide portion 43, a sealant holding portion 44, and a curved portion 45. The chamfered portion 42, the guide portion 43, the sealant holding portion 44, and the curved portion 45 are provided over the entire circumference in the circumferential direction. The chamfered portion 42 is formed on the upper end opening edge of the outer wall portion 41. The chamfered portion 42 faces upward and radially inward. The guide portion 43 is adjacent to the lower side of the chamfered portion 42. The guide portion 43 extends downward from the chamfered portion 42. The guide portion 43 extends in the axial direction with a constant inner diameter.

[0053] The sealant holding portion 44 is adjacent to the lower side of the guide portion 43. The sealant holding portion 44 has an uneven structure capable of holding a sealant having fluidity. As the sealant, for example, asphalt, epoxy resin, polyamide resin, butyl rubber adhesive, etc. can be used. The sealant is applied to the sealant holding portion 44, and then dried before use. The sealant holding portion 44 includes a plurality of convex portions 46 (five in the illustrated example) protruding radially inward and provided in the axial direction on the vertical cross section, and a groove portion 47 formed between the convex portions 46 adjacent to each other in the vertical direction. The convex portions 46 and the groove portion 47 are formed in an annular shape and extend over the entire circumference in the circumferential direction. The convex portions 46 taper radially inward. The tip of the convex portion 46 is located radially inward from the guide portion 43. The bottom of the groove portion 47 is located at the same position as the guide portion 43 in the radial direction.

[0054] The curved portion 45 is adjacent to the lower side of the sealant holding portion 44. The curved portion 45 is recessed radially outward and downward. The curved portion 45 extends in an arc shape on a vertical cross section. A lower end of the curved portion 45 smoothly connects to the top surface 33 of the base 31.

[0055] The inner wall portion 51 is formed in a cylindrical shape. The upper end edge 51a of the inner wall portion 51 is located below the height center 41C of the outer wall portion 41. The height center 41C of the outer wall portion 41 is the center position in the axial direction of the upper end edge (top surface 33) of the base portion 31 and the upper end edge 41a of the outer wall portion 41. The upper end edge 51a of the inner wall portion 51 is located at approximately the same position in the axial direction as the upper end edge of the sealant holding portion 44. In the illustrated example, the upper end edge 51a of the inner wall portion 51 is located slightly above the upper end edge of the sealant holding portion 44. The inner peripheral surface 52 of the inner wall portion 51 extends with a constant inner diameter in the axial direction. The inner peripheral surface 52 of the inner wall portion 51 has the same inner diameter as the upper portion of the inner peripheral surface 34 of the base portion 31, and is continuous with the inner peripheral surface 34 of the base portion 31. The outer peripheral surface 53 of the inner wall portion 51 extends at an angle with respect to the axial direction. The outer peripheral surface 53 of the inner wall portion 51 is smoothly connected to the top surface 33 of the base portion 31. The lower end of the outer peripheral surface 53 extends in an arc shape on the vertical cross section. The lower end of the outer peripheral surface 53 is recessed with a smaller radius of curvature than the curved portion 45 of the inner peripheral surface of the outer wall portion 41. The outer peripheral surface 53 extends radially inward from the bottom to the top. As a result, the inner wall portion 51 becomes gradually thinner from the bottom end to the top. The outer peripheral surface 53 extends in a straight line on the vertical cross section, except for its lower end.

[0056] The outer peripheral surface of the gasket 30 is provided from the base portion 31 to the outer wall portion 41. The outer peripheral surface of the gasket 30 includes a tapered portion 56. The tapered portion 56 overlaps the guide portion 43 and the sealant holding portion 44 when viewed from the radial direction. The upper end portion 56u of the tapered portion 56 is provided above the guide portion 43 when viewed from the radial direction. The lower end portion 56l of the tapered portion 56 is provided below the sealant holding portion 44 when viewed from the radial direction. In this embodiment, the tapered portion 56 is formed on the entire outer peripheral surface of the gasket 30. The tapered portion 56 gradually expands in diameter from the bottom to the top and extends radially outward. In other words, the tapered portion 56 extends radially outward from the lower end portion 56l when viewed from the top. As a result, the tapered portion 56 faces in a direction inclined downward from the outside in the radial direction. The tapered portion 56 extends linearly on the vertical cross section.

[0057] The axial dimension of the base 31 of the gasket 30 is larger than the maximum radial dimension of the outer wall portion 41 and the maximum radial dimension of the inner wall portion 51. The vertical dimension of the base 31 of the gasket 30 is the distance between the top surface 33 and the bottom surface 32 of the base 31.

[0058] The gasket 30 is preferably formed of a resin having a heat deformation temperature of 230° C. or higher. If the resin material used for the gasket 30 has a heat deformation temperature of 230° C. or higher, the gasket 30 is significantly deformed by heating during reflow soldering or use of the battery 1, and leakage of the electrolyte 11 can be prevented. Examples of materials for the gasket 30 include polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexane dimethylene terephthalate resin, polyether sulfone resin (PES), polyamino bismaleimide resin, polyetherimide resin, and fluororesin. Furthermore, glass fibers, mica whiskers, ceramic fine powder, etc. may be added to these materials in an amount of 30 mass % or less and these materials may be suitably used.

[0059] FIG. 4 is a vertical cross-sectional view showing the negative electrode can of the embodiment. As shown in FIG. 4, the negative electrode can 60 is formed in a cylindrical shape that opens downward. The negative electrode can 60 has a disk-shaped top 62 and a negative electrode can peripheral wall 64 that extends downward from the outer periphery of the top 62 all around toward an opening edge 61 of the negative electrode can 60. The negative electrode can 60 is formed by drawing a stainless steel plate. For example, SUS316L, SUS329J4L, or SUS304 can be used as the negative electrode can 60. Alternatively, for example, a clad material obtained by crimping copper, nickel, or the like onto stainless steel may be used as the negative electrode can 60.

[0060] The outer peripheral surface of negative electrode can peripheral wall 64 extends from the outer peripheral edge of top 62 toward opening edge 61 of negative electrode can 60 so as to expand in diameter. Negative electrode can peripheral wall 64 includes a double cylindrical portion 71 that extends upward from opening edge 61 of negative electrode can 60 toward top 62, and a step portion 65 that connects top 62 and double cylindrical portion 71.

[0061] The step portion 65 extends uniformly around the entire circumference in the circumferential direction. The step portion 65 includes a first curved portion 66, a second curved portion 67, and a third curved portion 68. The first curved portion 66 is connected to the outer peripheral edge of the top portion 62. The first curved portion 66 extends downward from the outer peripheral edge of the top portion 62. The first curved portion 66 is curved 90°. The first curved portion 66 is curved at a constant first radius of curvature on the vertical cross section on the outer peripheral surface of the negative electrode can peripheral wall portion 64. The second curved portion 67 extends radially outward from the lower end edge of the first curved portion 66. The second curved portion 67 is curved 90°. The second curved portion 67 is curved at a constant second radius of curvature on the vertical cross section on the outer peripheral surface of the negative electrode can peripheral wall portion 64. The second radius of curvature is smaller than the first radius of curvature. The third curved portion 68 extends downward from the outer peripheral edge of the second curved portion 67. The third curved portion 68 is curved at 90°. The third curved portion 68 is curved at a constant third radius of curvature on the vertical cross section on the outer peripheral surface of the negative electrode can peripheral wall portion 64. The third radius of curvature is smaller than the first radius of curvature. In the illustrated example, the third radius of curvature is equal to the second radius of curvature. Note that, as long as the lower end of the third curved portion 68 is continuous with the upper edge 72a of the inner cylinder portion 72 described later, the second curved portion 67 and the third curved portion 68 may be curved at an obtuse angle of less than 90°. In addition, in the illustrated example, a portion extending linearly in the axial direction on the vertical cross section is provided between the first curved portion 66 and the second curved portion 67, but the presence or absence of this linearly extending portion is not particularly limited.

[0062] The double cylinder portion 71 has an integral structure folded back at the opening edge 61 of the negative electrode can 60. The double cylinder portion 71 includes an inner cylinder portion 72 extending downward from the lower edge of the step portion 65 over the entire circumference, an outer cylinder portion 73 surrounding the inner cylinder portion 72 from the outside in the radial direction, and a folded back portion 74 provided at the opening edge 61 of the negative electrode can 60 and connecting the inner cylinder portion 72 and the outer cylinder portion 73.

[0063] The inner cylindrical portion 72 extends in the axial direction with a constant inner diameter and a constant outer diameter, continuing from the third curved portion 68. An upper end edge 72a of the inner cylindrical portion 72 coincides in the axial direction with the center of curvature of the third curved portion 68 on the longitudinal cross section.

[0064] The folded portion 74 connects the lower edge of the inner cylindrical portion 72 and the lower edge of the outer cylindrical portion 73. The folded portion 74 extends radially outwardly, curving 180° from the lower edge of the inner cylindrical portion 72. The lower surface of the folded portion 74 extends in a convex curved shape that protrudes downward on a vertical cross section.

[0065] The outer cylinder portion 73 extends upward from the folded portion 74 over the entire circumference. The outer cylinder portion 73 extends in the axial direction along the outer peripheral surface of the inner cylinder portion 72 with a constant inner diameter and a constant outer diameter. The inner peripheral surface of the outer cylinder portion 73 may be in contact with the outer peripheral surface of the inner cylinder portion 72, or may be slightly spaced from the outer peripheral surface of the inner cylinder portion 72. The outer diameter of the outer cylinder portion 73 is equal to the inner diameter of the guide portion 43 of the gasket 30. The upper end edge 73a of the outer cylinder portion 73 is formed in a flat shape perpendicular to the axial direction. The upper end edge 73a of the outer cylinder portion 73 is located on the top portion 62 side (upper) than the center 60C between both ends in the axial direction of the negative electrode can 60. The upper end edge 73a of the outer cylinder portion 73 is located above the upper end edge 72a of the inner cylinder portion 72. In other words, the outer cylinder portion 73 protrudes upward from the inner cylinder portion 72. Upper edge 73a of outer cylinder portion 73 is located below upper edge 68a of third curved portion 68. Upper edge 68a of third curved portion 68 coincides with the boundary between second curved portion 67 and third curved portion 68 on the outer peripheral surface of negative can peripheral wall portion 64, and is the point on the vertical cross section where the intersection angle between the tangent direction of the outer peripheral surface of negative can peripheral wall portion 64 and the axial direction is maximum.

[0066] A chamfered portion 75 is formed at the upper end of the outer peripheral surface of the outer tube portion 73. The chamfered portion 75 is formed over the entire circumference in the circumferential direction. In the illustrated example, the chamfered portion 75 has a so-called square chamfered shape. However, the normal direction of the chamfered portion 75 is not limited to a direction inclined at 45° with respect to the radial direction. The chamfered portion 75 may also have a so-called round chamfered shape.

[0067] As shown in FIG. 2, the negative electrode can 60 is attached to the gasket 30 with a sealant (not shown) applied to the sealant holding portion 44 of the gasket 30. The double cylinder portion 71 of the negative electrode can 60 is inserted into the annular groove between the outer wall portion 41 and the inner wall portion 51 of the gasket 30. The lower end edge of the double cylinder portion 71 (opening edge 61 of the negative electrode can 60) abuts against the top surface 33 of the base portion 31 of the gasket 30. The inner peripheral surface of the outer wall portion 41 of the gasket 30 is in close contact with the outer peripheral surface of the outer cylinder portion 73 of the double cylinder portion 71 over the entire circumference. The outer peripheral surface of the outer cylinder portion 73 is in contact with at least the entire sealant holding portion 44 of the inner peripheral surface of the outer wall portion 41 of the gasket 30. In the illustrated example, the double cylinder portion 71 is inserted inside the outer wall portion 41 so that the outer cylinder portion 73 crushes the convex portion 46 (see FIG. 3) of the sealant holding portion 44 of the gasket 30. The chamfered portion 75 and the upper edge 73a of the outer cylinder portion 73 are located above the sealant holding portion 44 and below the upper edge 41a of the outer wall portion 41. The negative electrode can 60 is attached to the gasket 30 and inserted inside the positive electrode can 20 together with the gasket 30. The negative electrode can 60 is positioned so that the top portion 62 protrudes upward from the positive electrode can 20.

[0068] The gasket 30 is inserted into the opening of the positive electrode can 20 from above. The bottom surface 32 of the base 31 of the gasket 30 is in contact with the upper surface of the bottom 22 of the positive electrode can 20. The outer peripheral surface of the gasket 30 is in close contact with the inner peripheral surface of the positive electrode can peripheral wall 24 over the entire circumference. The outer peripheral surface of the gasket 30 is in contact with the inner peripheral surface of the positive electrode can peripheral wall 24 over the entire axial length. Here, the gasket 30 is formed so that the tapered portion 56 of the outer peripheral surface faces downward rather than radially outward when it is alone, so that when it is inserted into the positive electrode can 20, it is pressed radially inward by the positive electrode can peripheral wall 24. As a result, the outer wall portion 41 of the gasket 30 is deformed so that the portion spaced radially from the negative electrode can 60 is displaced radially inward. In the illustrated example, the portion of the outer wall portion 41 of the gasket 30 located above the outer cylinder portion 73 of the negative electrode can 60 is displaced radially inward. As a result, the upper part of guide portion 43 on the inner peripheral surface of outer wall portion 41 of gasket 30 bulges radially inward above outer circumferential surface of outer tubular portion 73 of negative electrode can 60 .

[0069] As shown in FIG. 1, the positive electrode can 20 is crimped so as to squeeze the upper part of the positive electrode can peripheral wall 24. The opening edge 21 of the positive electrode can 20 is squeezed radially inward from the upper end edge 73a of the outer tubular portion 73 of the negative electrode can 60. By squeezing the upper part of the positive electrode can peripheral wall 24, the gasket 30 is deformed so that the part that was radially spaced from the negative electrode can 60 is displaced radially inward. As a result, the outer wall 41 of the gasket 30 is disposed from the radial outside of the outer tubular portion 73, passing above the outer tubular portion 73, to above the third curved portion 68. The outer wall 41 is in close contact with the chamfered portion 75 and the upper end edge 73a of the outer tubular portion 73 of the negative electrode can 60, and the third curved portion 68 of the step portion 65 from above. The negative electrode can 60 is also pressed downward by the upper part of the positive electrode can peripheral wall 24 via the gasket 30. Accordingly, the base 31 of the gasket 30 is pressed by the opening edge 61 of the negative electrode can 60 , so that the outer circumferential surface 53 of the inner wall 51 deforms to fit the inner circumferential surface of the negative electrode can peripheral wall 64 .

[0070] As described above, the inner peripheral surface of the outer wall portion 41 of the gasket 30 of the battery 1 of this embodiment includes the guide portion 43 that extends in the axial direction with a constant inner diameter, and the sealant holding portion 44 that is located between the guide portion 43 and the base portion 31 and is capable of holding a sealant. The outer peripheral surface of the outer wall portion 41 includes a tapered portion 56 that extends over the entire circumference in the circumferential direction and gradually increases in diameter from the bottom to the top.

[0071] According to this configuration, by inserting the negative electrode can peripheral wall portion 64 inside the sealant holding portion 44 holding the sealant, the sealant is disposed between the sealant holding portion 44 and the negative electrode can peripheral wall portion 64, so that the sealability between the gasket 30 and the negative electrode can 60 can be ensured. In addition, since the guide portion 43 extending in the axial direction with a constant inner diameter is formed on the opposite side of the base portion 31 with the sealant holding portion 44 in the axial direction, when the negative electrode can 60 is inserted inside the outer wall portion 41, the negative electrode can peripheral wall portion 64 can be smoothly guided toward the sealant holding portion 44. Furthermore, since the portion between the inner circumferential surface of the outer wall portion 41 and the tapered portion 56 becomes thicker toward the upper side, the gasket 30 with the negative electrode can 60 attached is inserted into the positive electrode can 20, and the opening edge 21 of the positive electrode can 20 is squeezed by crimping, so that the thick portion of the outer wall portion 41 of the gasket 30 can be pressed against the negative electrode can 60 to hold the negative electrode can 60 downward. In particular, when the negative electrode can peripheral wall 64 has a double-tube structure folded back at the opening edge 61, the thick portion of the outer wall 41 of the gasket 30 can be pressed against the upper edge 73a of the outer tube 73 to hold the negative electrode can 60 downward. Therefore, even in a battery 1 that has an increased thickness to increase the electric capacity, it is possible to prevent moisture from entering the inside through the opening of the positive electrode can 20 along the surface of the gasket 30. Therefore, by using the gasket 30 of this embodiment, a battery 1 that has excellent sealing properties and a large electric capacity and can be reflow soldered can be formed. In addition, since the battery 1 includes the above-mentioned gasket 30, it becomes a battery that has excellent sealing properties and a large electric capacity and can be reflow soldered.

[0072] Moreover, tapered portion 56 overlaps at least guide portion 43 when viewed from the radial direction. With this configuration, the provision of guide portion 43 in outer wall portion 41 allows the portion extending at a constant inner diameter to be formed thick. This makes it easier to attach negative electrode can 60 to gasket 30 while ensuring excellent sealing performance.

[0073] The sealant holding portion 44 includes a plurality of protrusions 46 provided in the axial direction, which protrude radially inward from the guide portion 43 and extend all around along the circumferential direction. As a result, a groove 47 is formed between the protrusions 46 adjacent to each other in the axial direction, so that the sealant holding portion 44 can easily hold the sealant having fluidity in the groove 47. In addition, the groove 47 between the protrusions 46 extends all around along the circumferential direction, so that the sealant holding portion 44 can hold the sealant all around. Furthermore, since the protrusions 46 protrude radially inward from the guide portion 43, the outer wall portion 41 can be reliably brought into contact with the outer peripheral surface of the negative electrode can 60. Therefore, by using the gasket 30, a battery 1 having excellent sealing properties can be formed.

[0074] The upper edge 51a of the inner wall 51 is located below the height center 41C of the outer wall 41 in the axial direction. With this configuration, the amount of displacement of the inner wall 51 can be reduced when the base 31 is pressed by the negative electrode can 60 pressed downward, compared to a configuration in which the upper edge of the inner wall is located above the height center 41C of the outer wall 41. This can prevent the inner wall 51 from applying a load to the positive electrode 5, the negative electrode 7, the separator 9, and the like. Therefore, the use of the gasket 30 can prevent defects such as an internal short circuit from occurring, and therefore a highly reliable battery 1 can be formed.

[0075] The dimension of the base 31 in the axial direction is larger than the maximum dimension of each of the outer wall 41 and the inner wall 51 in the radial direction. With this configuration, the thickness of the outer wall 41 can be secured, particularly in the portion close to the base 31. This ensures the strength of the gasket 30 in the battery 1, which has an increased thickness due to an increase in electric capacity. In addition, since a sufficient amount of the gasket 30 is disposed between the bottom 22 of the positive electrode can 20 and the opening edge 61 of the negative electrode can 60, the positive electrode can 20 and the negative electrode can 60 can be sufficiently tightly attached to the gasket 30 during the crimping process of the positive electrode can 20. Therefore, by using the gasket 30, the battery 1 can be formed with excellent sealing properties.

[0076] The gasket 30 further includes a gate portion 36 protruding radially inward from the inner peripheral surface of the base portion 31. The upper surface 37 of the gate portion 36 extends upward from the radially inner side to the radially outer side on the longitudinal section. According to this configuration, when the gasket 30 is injection molded, the molten resin flows from a cavity portion of the mold corresponding to the gate portion 36 to a cavity portion of the mold corresponding to the base portion 31. The molten resin that flows into the cavity portion of the mold corresponding to the base portion 31 flows into the cavity portion of the mold corresponding to the inner wall portion 51. At this time, the inner surface of the mold corresponding to the upper surface 37 of the gate portion 36 extends upward from the radially inner side to the radially outer side, that is, in the direction from the base portion 31 to the inner wall portion 51, so that the molten resin can be actively guided to the cavity portion of the mold corresponding to the inner wall portion 51. In particular, when the base portion 31 is formed thick, the resin is likely to accumulate in the cavity portion of the mold corresponding to the base portion 31, so that the inner wall portion 51 can be reliably formed by the above-mentioned action. Therefore, when the gasket 30 is formed by injection molding, the occurrence of molding defects such as insufficient filling can be suppressed.

[0077] Inner wall portion 51 tapers upward in a vertical cross section. This makes it easier to fill the molten resin to the deepest part of the cavity in the mold corresponding to inner wall portion 51. Therefore, when forming gasket 30 by injection molding, the occurrence of molding defects such as insufficient filling can be more reliably suppressed.

[0078] The upper edge 51a of the inner wall 51 is located below the upper edge 73a of the outer tubular portion 73 of the negative electrode can 60. With this configuration, the amount of displacement of the inner wall 51 can be reduced when the base 31 is pressed by the negative electrode can 60 pressed downward, compared to a configuration in which the upper edge of the inner wall is located above the upper edge 73a of the outer tubular portion 73. This can prevent the inner wall 51 from applying a load to the positive electrode 5, the negative electrode 7, the separator 9, etc. This can prevent the occurrence of defects such as an internal short circuit. This can therefore provide a highly reliable battery 1.

[0079] In the first embodiment shown in Fig. 2, the axial dimension of the base 31 of the gasket 30 is larger than the maximum radial dimension of the outer wall portion 41 and the maximum radial dimension of the inner wall portion 51, but the relationship in size between the base, the outer wall portion, and the inner wall portion is not limited to this. As shown in Fig. 5, the axial dimension of the base 131 of the gasket 130 may be smaller than the maximum radial dimension of the outer wall portion 41. Although not shown, the axial dimension of the base of the gasket may be smaller than the maximum radial dimension of the inner wall portion.

[0080] In the above embodiment, the inner wall portion 51 is gradually thinner from the lower end toward the upper end, but the shape of the inner wall portion is not limited to this. As shown in Fig. 5, the inner wall portion 151 may extend in the axial direction with a constant thickness.

[0081] In the above embodiment, the upper edge 51a of the inner wall portion 51 is located slightly above the upper edge of the sealant holding portion 44, but the positional relationship between the upper edge of the inner wall portion and the sealant holding portion is not limited to this. As shown in Fig. 5, the upper edge 151a of the inner wall portion 151 may be located below the upper edge of the sealant holding portion 44.

[0082] The present invention is not limited to the above-described embodiment explained with reference to the drawings, and various modifications are possible within the technical scope of the present invention. For example, in the above embodiment, gasket 30 contacts the upper surface of bottom 22 of positive electrode can 20, but the separator and positive electrode may be disposed between the gasket and the bottom of the positive electrode can, for example.

[0083] In the above embodiment, the convex portion 46 and the groove portion 47 of the sealant holding portion 44 are formed in an annular shape, but the shapes of the convex portion and the groove portion are not limited to this. For example, the convex portion and the groove portion may be formed in a spiral shape. The sealant holding portion may have a plurality of convex portions provided independently in the circumferential direction and the axial direction. The sealant holding portion may have a plurality of recesses provided independently. The sealant holding portion may be formed by roughening.

[0084] In the above embodiment, the chamfered portion 42 is formed on the outer wall portion 41 of the gasket 30, but the outer wall portion does not necessarily have to be formed with a chamfered portion. The guide portion may extend in the axial direction with a constant inner diameter from the upper end opening edge of the outer wall portion.

[0085] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0086] REFERENCE SIGNS LIST 1...battery (electrochemical cell) 5...positive electrode 7...negative electrode 20...positive electrode can 22...bottom 24...positive electrode can peripheral wall 30,130...gasket 31,131...base 34...inner peripheral surface of base 36...gate portion 37...upper surface (inclined surface) 41...outer wall 43...guiding portion 44...sealant retaining portion 46...projection 51,151...inner wall 56...tapered portion 60...negative electrode can 61...opening edge of negative electrode can 62...top 64...negative electrode can peripheral wall 71...double cylinder portion 72...inner cylinder portion 73...outer cylinder portion O...axis

Claims

1. 1. An annular gasket provided in an electrochemical cell having a cylindrical positive electrode can with a bottom, and a cylindrical negative electrode can with a top that is inserted into the positive electrode can and forms an accommodation space between the positive electrode can and the negative electrode can, a base portion extending circumferentially around the entire circumference and disposed between a bottom portion of the positive electrode can and an opening edge of the negative electrode can; an outer wall portion that protrudes from an outer periphery of the base in a first direction in an axial direction of a central axis of the base and extends entirely around the base along the circumferential direction, and is in close contact with an inner circumferential surface of the positive electrode can and an outer circumferential surface of the negative electrode can; an inner wall portion that protrudes inwardly from the base portion toward the outer wall portion in the first direction and extends entirely around the circumference along the circumferential direction; A gate portion protruding radially inward from an inner circumferential surface of the base portion; Equipped with The inner circumferential surface of the outer wall portion is a guide portion extending in the axial direction with a constant inner diameter; a sealant holding portion located between the guide portion and the base portion and capable of holding a sealant having flowability; Equipped with The outer circumferential surface of the outer wall portion includes a tapered portion extending over the entire circumference in the circumferential direction, The tapered portion gradually increases in diameter from the second direction in the axial direction to the first direction, a dimension of the base portion in the axial direction is greater than a maximum dimension of each of the outer wall portion and the inner wall portion in the radial direction; The entire gate portion protrudes from the inner circumferential surface of the base portion, an outer surface of the gate portion has an inclined surface that faces a direction inclined toward the first direction with respect to the radial direction, The inclined surface extends in the first direction from the inner side to the outer side in the radial direction on a longitudinal cross section along the central axis. Gaskets for electrochemical cells.

2. The tapered portion overlaps at least the guide portion when viewed from a radial direction.

10. A gasket for an electrochemical cell according to claim 1.

3. The sealant holding portion includes a plurality of protrusions provided in the axial direction, the protrusions protruding radially inward from the guide portion and extending over the entire circumference along the circumferential direction. A gasket for an electrochemical cell according to claim 1 or 2.

4. an edge of the inner wall portion in the first direction is located in the second direction relative to a center position in the axial direction of an edge of the base portion in the first direction and an edge of the outer wall portion in the first direction; A gasket for an electrochemical cell according to any one of claims 1 to 3.

5. The inner wall portion tapers in the first direction on the longitudinal cross section.

5. A gasket for an electrochemical cell according to claim 4.

6. A gasket for an electrochemical cell according to any one of claims 1 to 5; The positive electrode can and the negative electrode can, Equipped with the positive electrode can has a bottom and a positive electrode can peripheral wall extending in the first direction from an outer periphery of the bottom, the negative electrode can has a top and a negative electrode can peripheral wall extending in the second direction from an outer periphery of the top, the negative electrode can peripheral wall portion is disposed between the outer wall portion and the inner wall portion and is in contact with the sealing agent holding portion over the entire periphery; Electrochemical cell.

7. the negative electrode can peripheral wall portion includes a double cylinder portion extending in the first direction from an opening edge of the negative electrode can toward the top portion, The double cylinder portion has an inner cylinder portion extending in the axial direction and an outer cylinder portion surrounding the inner cylinder portion from the outside in the radial direction, an edge of the inner wall portion in the first direction is located in the second direction further than an edge of the outer tubular portion in the first direction; 7. The electrochemical cell of claim 6.

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