JP5420315B2 - Sealed battery and method for manufacturing the same - Google Patents

Description

  The present invention relates to a sealed battery, and more particularly to a sealed battery structure of a sealed battery provided with a sealed body with a safety valve.

  Nonaqueous electrolyte secondary batteries have high energy density and high capacity, and are therefore widely used as drive power sources for portable devices and electric tools.

  Since non-aqueous electrolyte secondary batteries use a flammable organic solvent, it is required to ensure the safety of the battery. For this reason, a current interrupting mechanism that operates when the battery internal pressure rises is incorporated into a sealing body that seals the battery.

  FIG. 1 shows a sealed battery provided with a sealing body incorporating a current interruption mechanism. As shown in FIG. 1, the sealing body 10 includes a terminal cap 5, a safety valve 3 positioned on the battery inner surface of the terminal cap, a terminal plate 1 positioned on the battery inner surface of the safety valve, the safety valve 3, and the terminal plate 1. And an insulating plate 2 that separates and insulates. Here, in order to keep the conductive contact between the terminal cap 5 and the safety valve 3, the pin-shaped protrusion 3c provided on the peripheral edge 3b of the safety valve is fitted into the counterbore hole 5c provided on the flange portion 5b of the terminal cap, and the rivet Both are fixed by fixing. Further, the vicinity of the center of the safety valve 3 has a convex shape toward the inside of the battery, and the vicinity of the apex of the convex shape is welded to the terminal plate 1 (energizing contact portion 3a). A crushing groove formed by reducing the thickness of the terminal plate 1 is formed around the periphery.

  The operation of the current interruption mechanism of the sealed battery will be described. When the battery internal pressure rises, the safety valve 3 is pushed out of the battery, the crushing groove of the terminal plate 1 connected to the energizing contact portion 3a of the safety valve 3 is broken, and the current supply to the terminal cap 5 is interrupted. .

  In such a current interruption mechanism, the safety valve needs to be able to perform the above operation smoothly, and its material is required to be easily deformed. On the other hand, since the terminal cap faces the external environment, the material is constant. Strength is required. For this reason, an aluminum-based material is used for the safety valve, and an iron-based material is used for the terminal cap.

  By the way, the battery temperature of the non-aqueous electrolyte secondary battery used for the purpose of discharging with a large current such as an electric tool may become a high temperature of 80 ° C. or higher during discharging. When the battery is repeatedly exposed to high temperatures, the elasticity of resin parts such as the insulating plate 2 and the gasket 30 is lost. When the elasticity of the resin part is lost, the contact between the terminal cap 5 and the safety valve 3 located around the resin part is loosened, and the internal resistance of the battery is likely to increase or become unstable. Therefore, it is desired that the terminal cap 5 and the safety valve 3 are fixed more firmly.

  The following patent document 1 is mentioned as a technique regarding a sealing body.

Japanese Patent Publication No. 5-74904

  Patent Document 1 discloses a battery cap having a cylindrical portion and a flange portion provided on the outer periphery of the cylindrical portion, and a plurality of convex portions having a protruding height larger than the plate thickness of the battery cap. The battery cap hole is fitted into the convex portion of the metal plate, and the end surface of the convex portion of the metal plate protruding from the hole of the battery cap is pressed to fix both. A sealing body is disclosed. However, this technique has a problem that the electrical connection between the battery cap and the metal plate is a pressure contact, and the internal resistance of the battery is not stable.

  This invention solves the said subject, and it aims at providing the sealed battery provided with the sealing body with a safety valve excellent in electroconductivity.

  The present invention relating to a method for manufacturing a sealed battery for solving the above-described problems is directed to a method for manufacturing a sealed battery that is sealed by caulking and fixing a sealing body 10 to an opening of a bottomed cylindrical outer can 20. The sealing body 10 is made of an iron-based material, and has an external terminal portion 5a protruding outward from the battery, a flange portion 5b positioned at the periphery of the external terminal portion 5a, and a battery outer surface provided on the flange portion 5b. A terminal cap 5 having a hole 5c having a smaller diameter on the inner side of the battery than the side, an energizing contact portion 3a made of an aluminum-based material and projecting inward of the battery, and positioned at the periphery of the energizing contact portion 3a Preparing a safety valve 3 having a peripheral portion 3b and a pin-like protrusion 3c provided on the peripheral portion 3b, and fitting the pin-like protrusion 3c of the safety valve into the hole 5c of the terminal cap. A rivet fixing step for crushing the tip of the pin-shaped protrusion 3c to fix the pin-shaped protrusion 3c and the hole 5c to a rivet, and on the battery inner surface side of the hole 5c of the terminal cap 5, Further, a corner drop portion 5d is provided.

  Since it is difficult to produce a pin-shaped protrusion with high accuracy (a vertical rise), an R portion 3d is generated at the root of the pin-shaped protrusion 3c as shown in FIG. For this reason, when a safety valve provided with such pin-shaped protrusions and a terminal cap are rivet-fixed, as shown in FIG. 7A, the battery inner end of the hole 5c of the terminal cap and the root of the pin-shaped protrusion 3c Since the R portion 3d comes into contact with each other, a gap is generated between them. Thereafter, when the battery is caulked, the caulking force acts so as to create this gap, so that a gap is formed between the head portion of the rivet and the upper surface of the hole, and the resistance between them increases. However, in the above configuration, since the corner drop portion 5d is formed, contact with the root R portion 3d of the pin-like protrusion 3c is prevented, as shown in FIG. It is difficult to create a gap. Therefore, even if battery caulking is performed, the contact between the two is kept good. Therefore, a sealed battery having a highly conductive sealing member with a safety valve is obtained.

  Although the same effect can be obtained by removing the root R portion after forming the pin-shaped protrusions, this method requires a fine processing, and thus costs are increased. On the other hand, the processing of the terminal cap on the hole 5c side can be easily performed (at low cost) by pressing, cutting, or the like.

  The shape of the angle drop part is preferably tapered.

  The width of the corner drop portion is preferably 15 to 30% of the thickness of the terminal cap, and the height of the corner drop portion is preferably 15 to 30% of the thickness of the terminal cap.

  The said structure WHEREIN: It can be set as the structure further equipped with the welding step which irradiates and welds the high energy beam to the said terminal cap of the said rivet fixed part vicinity.

  In the above method, the terminal cap side is irradiated with a high energy ray and welded. According to this method, the high energy ray melts the iron-based material having a high melting point of the terminal cap, and the molten iron-based material is melted. Then, it flows into the rivet fixing part located in the vicinity of the irradiation spot, and the aluminum-based material (pin-like protrusion of the safety valve) of the rivet fixing part is melted by the thermal energy of the molten iron material. Thereby, since both are fixed more firmly, electroconductivity increases more.

Here, when a high energy ray is irradiated to the safety valve side, the following problems occur.
(1) When an energy that melts an aluminum-based material having a low melting point is applied, an iron-based material having a high melting point hardly melts, so that good welding cannot be performed.
(2) When energy to the extent that an iron-based material having a high melting point is dissolved is applied, the aluminum-based material having a low melting point is evaporated, and good welding cannot be performed.

  Here, the iron-based material means iron and an iron alloy, and the aluminum-based material means pure aluminum and an aluminum alloy.

  As the high energy beam, it is preferable to use a laser beam whose energy is easily controlled.

  Further, in order to efficiently flow the molten iron material into the rivet fixing portion, it is preferable to irradiate the wall surface of the hole of the terminal cap 5 with high energy rays.

  In order to prevent the terminal cap and the safety valve from rotating after rivet fixation, it is preferable that the number of holes in the terminal cap and the number of pin-shaped protrusions of the safety valve be 2 or more, respectively. Moreover, it is preferable to set the upper limit to four each from the balance of cost and effect.

  Here, the clearance between the diameter of the pin-shaped protrusion of the safety valve and the diameter of the terminal cap hole on the inner side of the battery is preferably 0.01 to 0.1 mm. It is preferable that the height of the pin-shaped protrusion of the safety valve protrudes 0.3 to 0.7 mm toward the outer side of the hole battery on the battery inner side of the terminal cap. The diameter of the terminal cap hole on the battery outer side is preferably 0.2 to 0.7 mm larger than the diameter on the battery inner side.

  Further, the welding of the terminal cap and the safety valve may be performed so as to surround the entire outer periphery of the rivet fixing portion, or may be spot welding of one to several points.

  The sealed battery manufactured by the present invention according to the above-described method for manufacturing a sealed battery has the following two configurations (two configurations depending on the presence or absence of welding).

  In a sealed battery sealed by caulking and fixing the sealing body 10 to the opening of the bottomed cylindrical outer can 20, the external terminal portion 5 a made of an iron-based material and protruding outward from the battery, and the external terminal portion A terminal cap 5 having a flange portion 5b located at the periphery of 5a, a hole 5c provided in the flange portion 5b, having a diameter smaller on the battery inner surface side than on the battery outer surface side, and an aluminum-based material A safety valve 3 having a current-carrying contact portion 3a projecting inward of the battery, a peripheral portion 3b located at the periphery of the current-carrying contact portion 3a, and a pin-like protrusion 3c provided on the peripheral portion 3b, A pin-like protrusion 3c of the safety valve is fitted into the hole 5c of the terminal cap, and a rivet fixing portion in which the tip of the pin-like protrusion 3c is crushed, and the battery cap inner side of the hole 5c of the terminal cap 5 It is characterized in that the corners off portion 5d is provided.

In a sealed battery that is sealed by caulking and fixing the sealing body 10 to the opening of the bottomed cylindrical outer can 20, the sealing body 10 is made of an iron-based material, and the external terminal portion 5 a that protrudes outward from the battery. And a terminal cap 5 having a flange portion 5b located at the periphery of the external terminal portion 5a, and an energizing contact that is made of an aluminum-based material, is located inward of the battery from the terminal cap 5 and protrudes inward of the battery. A safety valve 3 having a portion 3a and a peripheral portion 3b located at the periphery of the energizing contact portion 3a, and a welded portion 7 in which the flange portion 5b of the terminal cap 5 and the peripheral portion 3b of the safety valve 3 are welded. The welded portion 7 is located between the battery inner surface and the battery outer surface of the flange portion 5b, the safety valve material is present at the center of the welded portion 7, and the periphery thereof. The terminal cap material The terminal cap 5 located on the battery inner surface side of the welded portion 7 is provided with a hole 5c, and the hole 5c is provided in the hole 5c. A part of the hole 5c is inserted, and a corner drop part 5d is provided in the hole 5c.

  According to the present invention, a sealing body with a safety valve excellent in conductivity can be obtained, and the current extraction efficiency of a sealed battery using this can be increased.

FIG. 1 is a cross-sectional view of a sealed battery according to the present invention. FIG. 2 is a view showing a terminal cap and a safety valve of a sealing body used in the sealed battery according to the present invention. FIG. 3 is a diagram for explaining a process of rivet-fixing the terminal cap and the safety valve in the sealed battery according to the present invention. FIG. 4 is a diagram for explaining a process of producing a terminal cap in the sealed battery according to the present invention. FIG. 5 is a diagram for explaining a process for producing a safety valve in the sealed battery according to the present invention. FIG. FIG. 6 is an enlarged cross-sectional view showing the vicinity of the pin-shaped protrusion of the safety valve. FIG. 7 is an enlarged cross-sectional view showing a state in which pin-shaped protrusions are inserted into counterbore holes. FIG. 7A shows a conventional battery and FIG. 7B shows a battery of the present invention. FIG. 8 shows a welding process after rivets are fixed in a sealed battery according to the present invention.

(Embodiment 1)
The best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is an enlarged cross-sectional view of a main part of the sealed battery according to the present embodiment.

  As shown in FIG. 1, in the sealed battery according to the present embodiment, the electrode body 40 and the electrolytic solution are accommodated in the outer can 20, and the sealing body 10 is caulked and fixed via the insulating gasket 30. .

  Moreover, the sealing body 10 used for the sealed battery according to the present embodiment has a terminal plate 1 electrically connected to the positive electrode or the negative electrode via the electrode tab 8 and an external terminal portion protruding outward from the battery. A safety valve 3 interposed between the terminal cap 5, the terminal plate 1 and the terminal cap 5, which is deformed when the internal pressure of the battery rises and cuts off the electrical connection between the terminal plate 1 and the terminal cap 5; The safety valve 3 includes an insulating member 2 that prevents electrical contact between the safety valve 3 and the terminal plate 1 when the current is cut off. One electrode of the electrode body 40 and the terminal plate 1 are connected via the electrode tab 8.

  FIG. 2 shows the terminal cap 5 and the safety valve 3 used in the present invention. As shown in FIG. 2A, the terminal cap 5 includes an external terminal portion 5a protruding outward from the battery, a flange portion 5b positioned on the periphery of the external terminal portion 5a, and a counterbored hole provided in the flange portion 5b. 5c and a corner drop portion 5d provided on the inner side of the battery in the countersunk hole. As shown in FIG. 2 (b), the safety valve 3 includes an energizing contact portion 3a protruding inward of the battery, a peripheral portion 3b located at the periphery of the energizing contact portion 3a, and pin-like protrusions provided on the peripheral portion 3b. 3c. As shown in FIG. 3C, the pin-like protrusion 3c is fitted into the counterbore hole 5c, the tip of the pin-like protrusion 3c is crushed, and both are fixed by rivet fixation. For this reason, the diameter of the counterbore hole 5c is battery outer side> battery inner end of taper part> small diameter part.

  Here, the counterbore hole 5c means a hole having a large diameter portion and a small diameter portion as shown in FIG. If it is a counterbore hole, the rivet can be fixed satisfactorily using the step portion at the boundary between the large diameter portion and the small diameter portion. However, even if the hole has a shape other than that, if the hole diameter is outside the battery> inside the battery, the rivet can be fixed using the difference in diameter.

Such a terminal cap 5 and the safety valve 3 are fixed as follows.
The terminal cap 5 is disposed on the upper surface of the safety valve 3, and the pin-like protrusion 3c of the safety valve 3 is fitted into the counterbore hole 5c of the terminal cap 5 (see FIG. 3A).
Then, it presses from the up-down direction using rivet fixing tool 51a, b, and crushes the front-end | tip part of the pin-shaped protrusion 3c, and forms a rivet fixing | fixed part (refer FIG.3 (b), (c)).

  After the rivet is fixed, the peripheral portion 3b of the safety valve 3 and the flange portion 5b of the terminal cap 5 may be welded using a high energy beam (for example, a laser). This welding method is shown in FIG.

  As shown in FIG. 8A, the terminal cap near the rivet fixing portion is irradiated with high energy rays (for example, laser). As a result, the terminal cap material having a high melting point melts, the molten terminal cap material flows into the rivet fixing portion, and the safety valve material having a low melting point of the rivet fixing portion melts. After cooling, the welded portion 7 between the terminal cap 5 and the safety valve 3 is positioned between the battery inner surface and the battery outer surface of the flange portion 5b of the terminal cap 5, as shown in FIG. In the central part of the part 7, there is aluminum as the material of the safety valve 3, and at its periphery, there is a molten and solidified region 9 in which iron which is the material of the terminal cap 5 and aluminum which is the material of the safety valve 3 are united. It is formed. In the figure, only the left side of the drawing shows a state where laser irradiation is performed.

  A method for manufacturing the lithium ion secondary battery having the above structure will be described.

<Preparation of positive electrode>
A ratio of 90: 5: 5 mass ratio of a positive electrode active material made of lithium cobaltate (LiCoO ₂ ), a carbon-based conductive agent such as acetylene black or graphite, and a binder made of polyvinylidene fluoride (PVDF). The sample is dissolved in an organic solvent composed of N-methyl-2-pyrrolidone and then mixed to prepare a positive electrode active material slurry.

  Next, using a die coater or a doctor blade, this positive electrode active material slurry is applied to both surfaces of a positive electrode core made of aluminum foil (thickness: 20 μm) with a uniform thickness.

  This electrode plate is passed through a dryer to remove the organic solvent, and a dry electrode plate is produced. The dried electrode plate is rolled using a roll press and cut to produce a positive electrode plate.

As the positive electrode active material used in the lithium ion secondary battery according to the present embodiment, for example, lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate, in addition to the above lithium cobaltate Lithium such as (LiFePO ₄ ), lithium manganese nickel cobaltate (LiMn _x Ni _y Co _z O ₂ , x + y + z = 1), or an oxide obtained by substituting some of the transition metals contained in these oxides with other elements The transition metal composite oxides can be used alone or in admixture of two or more.

<Production of negative electrode>
A negative electrode active material made of artificial graphite, a binder made of styrene butadiene rubber, and a thickener made of carboxymethylcellulose are weighed in a mass ratio of 98: 1: 1 and mixed with an appropriate amount of water. A negative electrode active material slurry is prepared.

  Next, using a die coater or a doctor blade, this negative electrode active material slurry is applied to both surfaces of a negative electrode core made of copper foil (thickness: 15 μm) with a uniform thickness.

  The electrode plate is passed through a dryer to remove moisture, and a dried electrode plate is produced. Then, this dry electrode plate is rolled by a roll press machine and cut to produce a negative electrode plate.

  Here, as a negative electrode material used in the lithium ion secondary battery according to the present embodiment, for example, natural graphite, carbon black, coke, glassy carbon, carbon fiber, or a carbonaceous material such as a fired body thereof, or the carbon A mixture of the material and one or more selected from the group consisting of lithium, a lithium alloy, and a metal oxide capable of occluding and releasing lithium can be used.

<Production of electrode body>
The positive electrode, the negative electrode, and a separator made of a polyethylene microporous film are wound by a winder, and an insulating winding tape is provided to complete a wound electrode body.

<Preparation of sealing body> (Preparation step)
The central portion of the nickel-plated iron plate is pressed using a press die 61 to form the external terminal portion 5a (convex portion) (see FIG. 4A).

  Thereafter, a punched hole is made in the flange portion 5b (the outer peripheral portion of the convex portion) (see FIG. 4B).

  Thereafter, the hole is pressed from above using a press die 62 to partially widen the diameter of the hole (see FIG. 4C). At this time, the diameter of the hole on the opposite side of the pressed surface is smaller than that shown in FIG.

  Thereafter, the hole narrowed by the press is expanded by punching the hole again (see FIG. 4D).

  Thereafter, by pressing with a press die 63, the corner of the hole inside the battery is dropped to form a corner drop portion 5d (see FIG. 4E).

  Thereafter, a terminal cap 5 having a counterbore 5c is manufactured by punching into a disk shape (see FIG. 4F).

  The center part of the aluminum plate is pressed using a press die 71 to form an energization contact part (recess 3a) (see FIG. 5A).

Thereafter, the peripheral portion 3b (outer peripheral portion of the convex portion) is pressed from the lower surface using the press dies 72a, b, c to form the pin-shaped protrusion 3c (see FIG. 5B).
Thereafter, it is punched into a disc shape to produce the safety valve 3 (see FIG. 5C).

  In this manufacturing method, a concave portion is formed on the opposite surface of the pin-like protrusion 3c by deformation due to pressing (see FIG. 5C). This concave portion is an essential configuration of the present invention. It is not an element.

  In the present embodiment, the size of each part is as follows. The diameter L1 of the terminal cap 5 is 16.5 mm, the thickness is 0.5 mm, the outer diameter L3 of the counterbored hole 5d is 1.4 mm, the inner diameter L4 of the counterbored hole 5d is 1.0 mm, and the height L2 of the inner diameter portion is 0.2 mm. The width L10 of the corner drop portion 5d is 0.1 mm (20% of the thickness of the terminal cap), and the height L11 of the corner drop portion 5d is 0.1 mm (20% of the thickness of the terminal cap). The diameter of the safety valve 3 is 16.5 mm, the thickness is 0.4 mm, the height L7 of the pin-shaped protrusion 3e is 0.5 mm, and the diameter L8 is 0.9 mm. The number of pin-shaped protrusions 3e of the safety valve and counterbored holes 5d of the terminal cap is 3 respectively.

(Rivet fixing step)
Thereafter, the terminal cap 5 is disposed on the upper surface of the safety valve 3, and the pin-shaped protrusion 3c of the safety valve 3 is fitted into the counterbore hole 5c of the terminal cap 5 (see FIG. 3A).
Then, it presses from the up-down direction using rivet fixing tool 51a, b, and crushes the front-end | tip part of the pin-shaped protrusion 3c, and forms a rivet fixing | fixed part (refer FIG.3 (b), (c)).

(Welding step)
A laser beam is applied to the wall surface of the hole of the terminal cap near the rivet fixing portion (see FIG. 8A), and the rivet fixing portion is welded (see FIG. 8B).

  Thereafter, an aluminum terminal plate 1 is welded to the lower surface of the safety valve 3 via a polypropylene insulating plate 2 to produce a sealing body 10.

<Preparation of electrolyte>
An electrolyte salt is added to a nonaqueous solvent in which ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 1: 8 (when converted to 1 atm and 25 ° C.). As an electrolytic solution, LiPF ₆ dissolved at a rate of 1.0 M (mol / liter) is used.

Here, the non-aqueous solvent used in the lithium ion secondary battery according to the present embodiment is not limited to the above combinations, and for example, lithium salts such as ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone. A high-dielectric-constant solvent with high solubility of diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, anisole, 1,4-dioxane, 4-methyl-2-pentanone, cyclohexanone, acetonitrile, pro It can be used by mixing with a low viscosity solvent such as pionitrile, dimethylformamide, sulfolane, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate. Furthermore, the high dielectric constant solvent and the low viscosity solvent can be used as a mixed solvent of two or more. In addition to the LiPF ₆ described above, for example, LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiClO _4, or LiBF ₄ may be used alone or in combination of two or more. Can be used.

<Battery assembly>
The positive electrode current collector of the electrode body and the bottom of the rectangular outer can are welded, injected into the electrolytic solution and the outer can, and electricity is supplied through the terminal plate of the sealing body, the negative electrode current collector, and the electrode tab 8. After the connection, the opening of the outer can is crimped and sealed through a polypropylene gasket, and the battery according to the present embodiment having a diameter of 18 mm and a height of 65 mm is assembled.

Example 1
A battery according to Example 1 was fabricated in the same manner as in the above embodiment except that the welding step was not performed. In addition, the number of pin-shaped protrusions of the safety valve and the holes of the terminal cap was 3 respectively.

(Example 2)
A battery according to Example 2 was fabricated in the same manner as in the above embodiment. In addition, the number of pin-shaped protrusions of the safety valve and the holes of the terminal cap was 3 respectively.

(Comparative Example 1)
A battery according to Comparative Example 1 was fabricated in the same manner as in Example 1 except that the corner drop portion was not provided in the hole of the terminal cap (see FIG. 6). In addition, the number of pin-shaped protrusions of the safety valve and the holes of the terminal cap was 3 respectively.

(Comparative Example 2)
A battery according to Comparative Example 2 was fabricated in the same manner as in Example 2 except that the corner drop portion was not provided in the hole of the terminal cap (see FIG. 6). In addition, the number of pin-shaped protrusions of the safety valve and the holes of the terminal cap was 3 respectively.

(Measurement of resistance)
Thirty pieces of each battery produced in the above examples and comparative examples were produced. At this time, after rivet caulking, after laser welding, and finally after sealing the opening of the battery can (hereinafter, this point is referred to as “after battery caulking”), the sealing body at each process step, and the constant current The battery is charged at 1250 mA (1 It) until the voltage reaches 4.2 V, and then charged at a constant voltage of 4.2 V until the current reaches 62.5 mA (0.05 It). The electrical resistance of the battery seal after storage for a day was measured. The results are shown in Table 1 below.

  In Table 1 above, numerical values outside the parentheses are average values, and numerical values outside the parentheses indicate variations.

  From Table 1 above, in Example 1 in which a corner drop portion was formed in the terminal cap hole, the resistance after caulking was 0.71 mΩ and the resistance after storage was 0.78 mΩ, whereas in the terminal cap hole, It can be seen that Comparative Example 1 in which no taper is formed is extremely large at 12.99 mΩ after battery caulking and 16.73 mΩ after storage.

  This is considered as follows. In both Example 1 and Comparative Example 1, only the contact between the safety valve and the terminal cap at the rivet fixing portion is performed. Moreover, in the said manufacturing method, R part will arise in the root part of a pin-shaped protrusion. Here, in Comparative Example 1 in which a corner drop portion is not formed in the counterbore hole 5c of the terminal cap, as shown in FIG. 7A, the battery inner end portion of the terminal cap hole 5c and the pin-like protrusion 3c are formed. Since the root R portion 3d comes into contact, a gap is generated between them. Thereafter, when the battery is caulked, the caulking force acts so as to create this gap, so that a gap is formed between the head portion of the rivet and the upper surface of the hole, and the resistance between them increases. In addition, due to a decrease in elasticity of the gasket due to storage, the fixation of both is weakened, and the conductivity after storage further decreases.

  On the other hand, in Example 1, since the corner drop part 5d is formed in the counterbore hole 5c, as shown in FIG. 7B, contact with the root R part 3d of the pin-like protrusion 3c is prevented. It is difficult to create a gap between the two. Therefore, even if battery caulking is performed, the contact between the two is kept good. Thereby, high electroconductivity is maintained.

  Also, from Table 1 above, Example 2 in which the hole in the terminal cap was tapered had a resistance after the caulking of 0.11 mΩ and a resistance after storage of 0.12 mΩ, whereas the resistance in the terminal cap hole was 0.12 mΩ. It can be seen that Comparative Example 2 having no taper is 17 to 18% larger, 0.13 mΩ after battery caulking and 0.14 mΩ after storage.

  This is considered as follows. Since both Example 2 and Comparative Example 2 perform laser welding, the conductivity is higher than that of Example 1 and Comparative Example 1. However, since the influence of the gap generated at the time of rivet fixing appears also at the time of caulking after firmly fixing by laser welding, the conductivity of Comparative Example 2 is lower than that of Example 2.

  As described above, according to the present invention, a sealing body with a safety valve excellent in conductivity can be realized, and the current extraction efficiency of a sealed battery equipped with the same can be improved. Therefore, the industrial significance is great.

DESCRIPTION OF SYMBOLS 1 Terminal board 2 Insulation board 3 Safety valve 3a Current supply contact part 3b Peripheral part 3c Pin-like protrusion 3d Root R part 5 Terminal cap 5a External terminal part 5b Flange part 5c Counterbore hole 5d Corner drop part 7 Welding part 8 Electrode tab 9 Melting solidification area DESCRIPTION OF SYMBOLS 10 Sealing body 20 Exterior can 30 Insulating gasket 40 Electrode body 51 Rivet fixture 61 Press die 62 Press die 63 Press die 71 Press die 72 Press die

Claims (7)

In the method of manufacturing a sealed battery sealed by caulking and fixing the sealing body (10) to the opening of the bottomed cylindrical outer can (20),
The sealing body (10)
An external terminal portion (5a) made of an iron-based material and projecting outward from the battery, a flange portion (5b) located at the periphery of the external terminal portion (5a), and provided on the flange portion (5b), A terminal cap (5) having a hole (5c) having a smaller diameter on the inner side of the battery than on the outer side of the battery, and an energizing contact portion (3a) made of an aluminum-based material and projecting inward of the battery, Preparation step for preparing a safety valve (3) having a peripheral part (3b) located at the periphery of the energization contact part (3a) and a pin-like protrusion (3c) provided on the peripheral part (3b) When,
The pin-shaped protrusion (3c) of the safety valve is fitted into the hole (5c) of the terminal cap, and the tip of the pin-shaped protrusion (3c) is crushed so that the pin-shaped protrusion (3c) and the hole (5c) are A rivet fixing step for fixing rivets;
With
On the battery inner surface side of the hole (5c) of the terminal cap (5), a corner drop part (5d) is provided.
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 1,
The shape of the angle drop part (5d) is tapered.
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 1 or 2,
The width of the corner drop part (5d) is 15 to 30% of the thickness of the terminal cap (5), and the height of the corner drop part (5d) is 15 to 15% of the thickness of the terminal cap (5). 30%,
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 1, 2, or 3,
After the riveting step, further comprising a welding step of irradiating a high energy beam to the terminal cap of rivets fixing the vicinity, welded,
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 4,
The high energy beam is a laser;
A method for producing a sealed battery, comprising: In a sealed battery sealed by caulking and fixing a sealing body (10) to an opening of a bottomed cylindrical outer can (20),
An external terminal portion (5a) made of an iron-based material and projecting outward from the battery, a flange portion (5b) located at the periphery of the external terminal portion (5a), and provided on the flange portion (5b), A terminal cap (5) having a hole (5c) having a smaller diameter on the inner side of the battery than on the outer side of the battery, and an energizing contact portion (3a) made of an aluminum-based material and projecting inward of the battery, A safety valve (3) having a peripheral part (3b) located at the periphery of the energization contact part (3a), and a pin-like protrusion (3c) provided on the peripheral part (3b); and a pin shape of the safety valve A protrusion (3c) fitted into the hole (5c) of the terminal cap, and a rivet fixing portion in which the tip of the pin-shaped protrusion (3c) is crushed,
On the battery inner surface side of the hole (5c) of the terminal cap (5), a corner drop part (5d) is provided.
A sealed battery characterized by that. In a sealed battery sealed by caulking and fixing a sealing body (10) to an opening of a bottomed cylindrical outer can (20),
The said sealing body (10) consists of an iron-type material, and has the external terminal part (5a) which protruded outward of the battery, and the flange part (5b) located in the periphery of the said external terminal part (5a) A cap (5), made of an aluminum-based material, located inward of the battery from the terminal cap (5) and projecting inward of the battery, and on the periphery of the energized contact portion (3a) A safety valve (3) having a peripheral part (3b) positioned, and a welded part (7) in which a flange part (5b) of the terminal cap (5) and a peripheral part (3b) of the safety valve (3) are welded. ) And
The welded portion (7) is located between the battery inner surface and the battery outer surface of the flange portion (5b), the safety valve material is present at the center of the welded portion (7), and the peripheral edge thereof. The terminal cap material and the safety valve material have a melt-solidified region (9) in which
A hole (5c) is provided in the terminal cap (5) located on the battery inner surface side of the weld (7), and a part of the safety valve (3) is inserted into the hole (5c),
A corner drop part (5d) is provided in the hole (5c),
A sealed battery characterized by that.

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