JPH09129213A - Manufacture of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a battery having the terminal part of a sealing plate with a terminal and a strip type tab fixed at least at two positions and with uniform welding strength by improving a welding method. SOLUTION: This method has the end of the strip type tab 7 of one electrode and the terminal part of a sealing plate 12 having another electrode terminal connected to each other at two or more positions. Furthermore, the connection part is formed to position the end of the strip type tab 7 at the terminal part, and lay a support electrode 16 on the surface of the sealing plate 12 at the opposite side of the terminal part. Also, a plurality of point electrodes are kept in contact with the strip type tab 7 via a travel distance adjustment mechanism. Thereafter, a direct spot welding process is implemented under the application of weld current across the support electrode 16 and a plurality of the point electrodes evenly pressed with a presser mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a battery having a structure in which a terminal and an electrode having the same polarity as the terminal are electrically connected by a strip-shaped tab.

[0002]

2. Description of the Related Art As a battery used for portable electric equipment or the like, a manganese battery, a carbon rod such as an alkali manganese battery, or a battery for electrically connecting an active material and a terminal with a collector rod, a lithium battery, A sealing plate having a positive electrode terminal, in which an electrode group made by interposing a separator between a positive electrode and a negative electrode represented by an alkaline secondary battery is housed in a metal case, and having a positive electrode terminal attached to the opening of the metal case. It is known that the positive electrode housed in the metal case has a structure in which it is electrically connected by a strip-shaped tab.

A battery having a structure in which the terminal and the electrode are electrically connected by a strip tab is manufactured by, for example, the following method. First, an electrode group is produced by interposing a separator between a positive electrode having a strip tab and a negative electrode. The electrode group is housed in a bottomed cylindrical container in which a step is formed by expanding the opening in advance, or the electrode group is housed in a bottomed cylindrical container and then externally placed in the container. A bead is inserted to form a step. In this way, the electrolytic solution is injected into the container containing the electrode group. Then, the sealing plate having the positive electrode terminal is housed in a bottomed cylindrical insulating gasket formed of synthetic resin and having a hole at the bottom. After connecting the tip of the band-shaped tab to the lower surface of the sealing plate, the insulating gasket accommodating the sealing plate is placed on the stepped portion in the container. Continuing, the opening of the container is reduced in diameter, a bent portion is formed by bending the upper end of the opening inward, and the sealing plate is caulked and fixed to the container by the repulsive elastic force of the insulating gasket. Thus, the battery is manufactured.

Conventionally, one point is fixed to the lower surface of the sealing plate and the tip of the strip-shaped tab by spot welding. However, since the welding area easily varies, there is a problem that the discharge characteristics of the battery deteriorate when the welding area becomes small.

For this reason, the lower surface of the sealing plate and the tip of the strip-shaped tab are fixed by spot welding at two points. In the spot welding, the tip of the strip-shaped tab is arranged on the lower surface of the sealing plate, the support electrode is arranged on the upper surface of the sealing plate, and 2 is formed on the tip of the strip-shaped tab.
This is performed by arranging two spot electrodes and applying a welding current between the support electrode and the spot electrode while pressing the tip of the strip-shaped tab with the two spot electrodes.

By the way, since the strip tab is a thin plate made of metal such as nickel, wrinkles and distortion are likely to occur during handling. On the other hand, since the sealing plate is housed in the insulating gasket, the peripheral edge of the lower surface of the sealing plate projects by the thickness of the insulating gasket. Therefore, since the strip-shaped tabs are arranged on the surface having irregularities, extra wrinkles and distortion are likely to occur.

The two spot electrodes are integrated, and the two spot electrodes move up and down together by the same distance. If such a spot electrode is arranged at the tip of the strip-shaped tab having wrinkles or distortion, the contact between any one of the electrodes and the strip-shaped tab becomes insufficient, so that the welding current varies and the welding strength varies. The problem arises. As a result, in the battery manufactured by such a method, the current concentrates on one of the connection points of the strip-shaped tab and the sealing plate, which has a higher welding strength, so that the current collecting efficiency of the positive electrode is reduced and The operating voltage drops. Further, when the battery is externally short-circuited and an abnormal current flows through the strip-shaped tab, the abnormal current concentrates on a connection point having a high welding strength, so that this connection point is excessively heated and, as a result, the temperature of the battery is reduced. May be abnormally high.

As the sealing plate having the positive electrode terminal, a sealing plate having a hat-shaped positive electrode terminal fixed by welding, a sealing plate having a cap-shaped positive electrode terminal fixed by caulking, and the like are used. The sealing plate to which the hat-shaped positive electrode terminal is fixed by welding is widely used because it can be manufactured more easily than the sealing plate to which the cap-shaped positive electrode terminal is caulked and fixed. However, if the positive electrode terminal is fixed to the sealing plate by welding, the positive electrode terminal may be fixed to the sealing plate in a slightly inclined state depending on welding conditions. Even if such a sealing plate is used for a battery, the battery characteristics are not hindered. However, if the sealing plate and the band-shaped lead are fixed at two points by the spot welding described above, the sealing plate and the strip-shaped lead are Since the contact between one side and the strip-shaped tab becomes insufficient, the welding strength varies,
The same problem as described above occurs.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to improve a welding method by using a battery in which a terminal portion of a sealing plate having a terminal and a strip tab are fixed at at least two places and with uniform welding strength. It is to provide a manufacturing method.

[0010]

In the method of manufacturing a battery according to the present invention, an electrode group and an electrolytic solution produced by interposing a separator between one electrode having a strip-shaped tab and the other electrode are used for the other electrode terminal. A structure that is housed in a container that also serves as the container, the opening of the container is sealed by a sealing plate having a one-pole terminal, and the tip end portion of the strip tab and the terminal portion of the sealing plate are connected at two or more points. In the method for manufacturing a battery having, the connection between the tip of the strip-shaped tab and the terminal of the sealing plate adjusts the moving distance according to the support electrode for supporting the sealing plate and the unevenness of the welding location. Using a plurality of point electrodes having a moving distance adjusting mechanism and a pressurizing mechanism for pressurizing a welding point, the tip portion of the strip tab is arranged at the terminal portion of the sealing plate, and the sealing plate Support on the surface opposite to the terminal After arranging a pole, the plurality of point electrodes are moved to the tip end portion of the strip tab by a distance corresponding to the unevenness of the tip portion by the movement distance adjusting mechanism and brought into contact with each other, and then the plurality of point electrodes are pressed by the pressing mechanism. It is characterized in that it is carried out by a method comprising a step of performing direct spot welding in which a welding current is applied between the supporting electrode and the plurality of point electrodes while applying pressure evenly to the point electrodes.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A battery (for example, a cylindrical battery) manufactured by the method according to the present invention will be described below with reference to FIG. An electrode group 5 made by stacking a positive electrode 2, a separator 3 and a negative electrode 4 and spirally winding them is housed in a bottomed cylindrical container 1 that also serves as a negative electrode terminal. The positive electrode 2 has a lead portion 6 formed at an end portion along the longitudinal direction and a strip-shaped tab 7 formed on the lead portion 6. The negative electrode 4 is arranged at the outermost periphery of the electrode group 5 and is in electrical contact with the container 1. The electrolyte is
It is housed in the container 1. A sealing member 8 having an explosion-proof function and a positive electrode terminal is arranged in the upper opening of the container 1. An insulating gasket 10 made of synthetic resin and having a bottomed cylindrical shape with a hole 9 opened at the bottom is arranged in a compressed state between the peripheral edge of the sealing member 8 and the inner surface of the upper opening of the container 1. The insulating gasket 10 can be formed of, for example, a polyamide-based synthetic resin such as nylon 6,6. The sealing member 8 is caulked and fixed to the container 1 while the insulating gasket 10 is compressed. As shown in FIG. 2, the sealing member 8 has a cap shape having a circular sealing plate 12 having a gas vent hole 11 in the center, an elastic valve body 13 made of, for example, synthetic rubber, and a plurality of gas passage holes 14. It is composed of the positive electrode terminal 15. The strip-shaped tab 7 is fixed to the lower surface of the sealing plate 12 at two points at the tip.

Next, a method of manufacturing the above-mentioned battery will be described. (First step) The electrode group 5 is manufactured so that the negative electrode 4 is located at the outermost periphery with the separator 3 interposed between the positive electrode 2 having the lead portion 6 and the strip-shaped tab 7 and the negative electrode 4. . The electrode group 5 and the electrolytic solution are housed in the container 1.

Next, the positive electrode 2, the negative electrode 4, the separator 3 and the electrolytic solution will be described. 1) Positive Electrode 2 The positive electrode 2 is made of a current collector filled with a paste containing a positive electrode active material, and has a lead portion 6 at an end portion along the longitudinal direction.
Having. The lead portion 6 has a strip-shaped tab 7.

The lead portion 6 and the strip-shaped tab 7 can be made of nickel, for example. For the positive electrode, for example, after preparing a paste containing a positive electrode active material, a conductive agent, a binder, and water, the current collector is filled with the paste, dried, and then pressure-molded by a press. Can be manufactured by.

Examples of the positive electrode active material include nickel compounds. Examples of the nickel compound include nickel hydroxide, nickel hydroxide in which zinc and cobalt are coprecipitated, and nickel oxide. Among them, it is preferable to use nickel hydroxide in which zinc and cobalt are coprecipitated.

The conductive agent may be, for example, one or more selected from cobalt compounds and metallic cobalt. Examples of the cobalt compound include cobalt hydroxide (Co (OH) ₂ ) and cobalt monoxide (CoO). Especially,
It is preferable to use a conductive material composed of cobalt hydroxide, cobalt monoxide, or both cobalt hydroxide and cobalt monoxide.

Examples of the binder include hydrophobic polymers such as polytetrafluoroethylene (PTFE), polyethylene and polypropylene, such as carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl methyl cellulose (HPMC) such as poly. Examples thereof include polyacrylic acid salts such as sodium acrylate (SPA), hydrophilic polymers such as polyvinyl alcohol (PVA) and polyethylene oxide, and rubber-based polymers such as latex.

As the current collector, for example, nickel,
Examples thereof include a net-like, sponge-like, fibrous, or felt-like porous metal body formed of a metal such as stainless steel or an alkali resistant material such as a resin plated with nickel. 2) Negative Electrode 4 This negative electrode 4 preferably has a structure in which a current collector is filled with a paste containing a negative electrode active material.

For such a negative electrode, for example, after preparing a paste containing a negative electrode active material, a conductive material, a binder and water, the paste is filled in a current collector, dried and then pressed. It can be produced by pressure molding.

As the negative electrode active material, it is possible to use a substance which directly participates in a charge / discharge reaction or a substance which occludes / releases a substance directly involved in a charge / discharge reaction. Examples of the former include powders of cadmium compounds such as cadmium metal and cadmium hydroxide. Examples of the latter include a hydrogen storage alloy that stores and releases hydrogen. Among them, the secondary battery provided with the negative electrode containing the hydrogen storage alloy is capable of discharging a large current and less likely to cause environmental pollution as compared with the secondary battery provided with the negative electrode containing the powder of the cadmium compound. Therefore, it is preferable.

The hydrogen storage alloy is not particularly limited as long as it can store hydrogen electrochemically generated in the electrolytic solution and can easily release the stored hydrogen during discharge. . For example, LaNi ₅ , MmN
i ₅ (Mm; misch metal), LmNi ₅ (Lm; lanthanum-enriched misch metal), or Ni
A part of Al, Mn, Co, Ti, Cu, Zn, Zr,
Examples thereof include a multi-element type substituted by elements such as Cr and B, or a TiNi type, TiFe type, ZrNi type, or MgNi type. Among them, the general formula LmNi
_x Mn _y A _z (However, A is Al, shows at least one metal selected from Co, the atomic ratio x, y, z is the total value of 4.8 ≦ x + y + z ≦ 5.4) hydrogen represented by It is desirable to use an occlusion alloy. The cylindrical secondary battery provided with the negative electrode containing the hydrogen storage alloy having such a composition can have improved discharge capacity and charge / discharge cycle life.

Examples of the conductive material include nickel powder, cobalt oxide, titanium oxide, carbon black and the like. In particular, it is preferable to use the carbon black as a conductive material.

As the binder, the same binder as described above for the positive electrode can be used. Examples of the current collector include a two-dimensional substrate such as a punched metal, an expanded metal, a perforated rigid plate, and a nickel net, a felt-like metal porous body, and a three-dimensional substrate such as a sponge-like metal substrate. Can be. 3) Separator 3 As the separator 3, for example, a nonwoven fabric made of a polyolefin fiber, such as a nonwoven fabric made of polyethylene fiber, a nonwoven fabric made of ethylene-vinyl alcohol copolymer fiber, or a nonwoven fabric made of polypropylene fiber, provided with a hydrophilic functional group,
For example, a nonwoven fabric made of polyamide fiber such as nylon 6,6 can be used. Examples of a method for imparting a hydrophilic functional group to the polyolefin fiber nonwoven fabric include a corona discharge treatment, a sulfonation treatment, a graft copolymerization, and the application of a surfactant or a hydrophilic resin. 4) Electrolyte solution Examples of the electrolyte solution include sodium hydroxide (Na).
OH) aqueous solution, lithium hydroxide (LiOH) aqueous solution, potassium hydroxide (KOH) aqueous solution, NaOH and L
An alkaline electrolyte such as a mixed solution of iOH, a mixed solution of KOH and LiOH, a mixed solution of KOH, LiOH and NaOH can be used. (Second step) The sealing member 8 which also has the explosion-proof function and the positive electrode terminal is housed in the insulating gasket 10. (Third Step) First, the supporting electrode used in this step will be described with reference to FIG.

The support electrode 16 has a prismatic shape with a rectangular recess 17 formed at the center of the lower end. Since the supporting electrode having such a structure has a large contact area with the sealing member,
It is possible to disperse the welding current, and it is possible to avoid welding defects that occur when a large current flows.

Next, a plurality of point electrodes provided with a moving distance adjusting mechanism for adjusting the moving distance according to the unevenness of the welding spot and a pressurizing mechanism for uniformly applying pressure to the welding spot will be described with reference to FIG. .

The balance head 18, which also serves as the moving distance adjusting mechanism and the pressing mechanism, has two point electrodes 19a and 19b at the lower end. The moving distance adjusting mechanism,
When the balance head 18 main body is lowered to lower the two point electrodes 19a and 19b, and either one of the electrodes comes into contact with the welding point, the contacted electrodes are removed even if the balance head 18 main body is further lowered. Only the electrode which is fixed at that position but is not in contact with the electrode is lowered to contact the welded portion.

A welding process using the support electrode and the point electrode described above will be described. As shown in FIG. 3, the supporting electrode 17 is arranged on the sealing plate 12 of the sealing member 8 so that the recess 16 of the electrode 17 surrounds the top of the positive electrode terminal 15. As shown in FIG. 5, the tip of the strip-shaped tab 7 is arranged on the surface of the sealing plate opposite to the terminal 15 which is the terminal portion of the sealing plate 12. Since the gasket 10 is arranged on the peripheral edge of the terminal portion and protrudes by the thickness of the gasket compared to the vicinity of the center, the strip-shaped tab 7 is arranged in a slightly bent state on the terminal portion. The balance head 18 body is lowered to lower the two electrodes 19a and 19b. When one of the electrodes comes into contact with the tip of the strip-shaped tab 7, the moving distance adjusting mechanism is driven and only the other electrode descends to move the two electrodes 19a as shown in FIG. , 19b are brought into contact with the front end of the strip-shaped tab 7. Therefore, even when the band-shaped tab 7 is wrinkled or distorted due to the arrangement of the band-shaped tab 7 as described above, or when the sealing member having the defective welding is used, the movement distance adjusting mechanism 2 The electrodes 19a and 19b of the book can be moved to a distance corresponding to the unevenness of the welding location and brought into contact with the welding location. As a result, the pressure adjusting mechanism of the balance head 18 can apply a pressure evenly to the two electrodes 19a and 19b, so that the electrode 17 and the two electrodes 19 can be applied.
When a welding current is passed between a and 19b, the welding current flows evenly, and the terminal portion of the sealing plate 12 and the strip-shaped tab 7 can be fixed uniformly and with high welding strength. Therefore, it is possible to avoid the electric current from concentrating on one of the welding points of the strip-shaped tab, so that it is possible to realize a battery with a high operating voltage and a high safety in which the temperature rise during the external short circuit is suppressed. be able to. (Fourth step) The sealing member housed in the insulating gasket is placed on the stepped portion of the container, the opening of the container is reduced in diameter, and the upper end of the opening is bent inward to form the container. A cylindrical battery is manufactured by caulking and fixing the sealing member via the insulating gasket.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. Example <Preparation of Paste Type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to 0.3 parts by weight of carboxymethyl cellulose and polytetrafluoroethylene with respect to the nickel hydroxide powder. 0.5 parts by weight of the suspension (specific gravity 1.5, solid content 60% by weight) in terms of solid content is added, and 45 parts by weight of water as a dispersion medium is added to the solid content and kneaded to obtain a paste. Was prepared. Subsequently, this paste was filled in a nickel-plated fiber substrate as a conductive substrate except for the end portion on the longitudinal direction side, dried, and rolled by roller pressing. A paste-type positive electrode was produced by attaching a strip-shaped tab having a lead portion to a portion not filled with paste by resistance welding. The tab with lead is formed of nickel, for example, and the tab portion has a thickness of 0.15 m.
m, the width is 4 mm.

<Preparation of paste type negative electrode> Commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn, A
LmNi _4.0 Co _0.4 M by a high frequency furnace using
A hydrogen storage alloy having a composition of n _0.3 Al _0.3 was prepared. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. 0.5 parts by weight of sodium polyacrylate based on 100 parts by weight of the obtained alloy powder,
1.25 parts by weight of carboxymethylcellulose (CMC) and a dispersion of polytetrafluoroethylene (specific gravity 1.5, solid content 60 wt%) were converted to solid content.
A paste was prepared by mixing 5 parts by weight and 1.0 part by weight of carbon powder as a conductive material with 50 parts by weight of water as a dispersion medium. This paste was applied to a punched metal, dried, and then pressure-molded to produce a paste-type negative electrode.

Next, a separator made of a hydrophilic non-woven fabric made of polyolefin fiber was interposed between the negative electrode and the positive electrode and spirally wound to form an electrode group. The electrode group is housed in a bottomed cylindrical container that also serves as a negative electrode terminal in which a step portion having a shape protruding inward is formed at the lower end of the opening by expanding the opening portion in advance. An electrolytic solution containing 7N KOH and 1N LiOH was housed in.

On the other hand, the sealing member 21 shown in FIG. 6 was prepared. The sealing member 21 is made of nickel-plated steel, has a circular sealing plate 23 having a gas passage hole 22 in the center, and an elastic member arranged on the sealing plate 23 so as to close the gas passage hole 22. The valve body 24 and a positive electrode terminal cap 26 having a plurality of gas vent holes 25 are fixed on the sealing plate by resistance welding in a slightly inclined state so as to surround the elastic valve body. A bottomed cylindrical shape having a circular hole at the bottom was formed, and the sealing member was placed in an insulating gasket made of nylon 6,6.

As shown in FIG. 7, the insulating gasket 27 is used.
The supporting electrode 17 is arranged on the sealing plate 23 of the sealing member 21 housed therein so that the recess 16 surrounds the protruding portion of the positive electrode terminal 26, and the terminal portion of the sealing plate 23, that is, the terminal 26 is The front end of the strip-shaped tab 7 was arranged on the surface opposite to the fixed surface in a slightly bent state. The balance head 18 is lowered to lower the two electrodes 19
a and 19b were lowered. When the electrode 19a comes into contact with the tip of the strip-shaped tab 7, the movement distance adjusting mechanism is driven and only the other electrode 19b descends so that the two electrodes 19a and 19b are attached to the tip of the strip-shaped tab 7. Was touched by.

When the two electrodes 19a, 19b are brought into contact with the tip end of the strip-shaped tab 7, the pressure applying mechanism of the balance head 18 is driven to drive the two electrodes 19a, 19b.
The tip of the strip-shaped tab 7 was pressed by b, the strip-shaped tab 7 and the sealing member 21 were sandwiched between the electrode 17 and the electrodes 19a and 19b, and pressure was applied evenly to the two welding points. In this state, a welding current was passed between the electrode 17 and the electrodes 19a and 19b to fix the strip tab 7 to the terminal portion of the sealing plate 23 of the sealing member 21 by direct spot welding. After placing the sealing member 21 housed in the insulating gasket 27 on the stepped portion of the container, the opening portion is reduced in diameter, and the upper end of the opening portion is bent inward to close the sealing member. The nickel-metal hydride secondary battery of AA size shown in FIG. 1 described above was manufactured by caulking and fixing it in the container through. Comparative Example 1 The AA size nickel-hydrogen secondary battery shown in FIG. 1 was manufactured by the same method as in Example except that two point electrodes having no moving distance adjusting mechanism were used.

That is, as shown in FIG. 8, a prismatic support electrode 32 having a rectangular recess 31 in the center is arranged in the sealing plate 23 of the sealing member 21 so that the recess 31 surrounds the protruding portion of the terminal 26. Then, the tip end of the strip-shaped tab 7 was arranged on the surface of the sealing plate 23 opposite to the terminal 26, which is the terminal portion, with the tip thereof slightly bent. Two point electrodes 33a and 33b having no moving distance adjusting mechanism are arranged at the tip of the strip-shaped tab 7. Since the positive electrode terminal 26 is fixed to the sealing plate 23 in an inclined state, a gap is generated between the point electrode 33b and the sealing plate 23. A welding current is caused to flow between the support electrode 32 and the two point electrodes 33a, 33b while pressing the tip of the band-shaped tab 7 with the two point electrodes 33a, 33b, and the band-shaped tab 7 is sealed. It was fixed to the terminal portion of the plate 23 by direct spot welding. Comparative Example 2 Sealing member 2 by series spot welding described below
The AA size nickel-hydrogen secondary battery shown in FIG. 1 was manufactured by the same method as that of the example except that 1 and the strip tab 7 were fixed at two points.

As shown in FIG. 9 described above, a support member 35 made of an insulating material is formed in the sealing plate 23 in the shape of a prism having a rectangular recess 34 opened in the center, and the recess 34 protrudes from the terminal 26. Is disposed so as to surround the
The strip-shaped tab 7 was arranged on the surface opposite to the surface to which the terminal 26 as the terminal portion of FIG. At the same time, the two point electrodes 36 (− side) and 37 (+ side) equipped with the same balance head as in the embodiment are lowered, and the moving distance adjusting mechanism of the balance head adjusts the two electrodes at the tip of the strip-shaped tab 7. Point electrode 3
6, 37 are brought into contact with each other, and a welding current is caused to flow between the two point electrodes 36, 37 while uniformly applying pressure to each of the point electrodes 36, 37 by the pressing mechanism of the balance head. The strip-shaped tab 7 is attached to the sealing plate 2
It was fixed to the terminal portion of No. 3 by series spot welding.

100 pieces of each of the obtained secondary batteries of Example 1 and Comparative Examples 1 and 2 were prepared, and the tensile welding strength and its variation (standard deviation σ) were examined, and the results are shown in Table 1 below.

Further, the obtained Example 1 and Reference Examples 1 and 2 were obtained.
After charging 150% at 0.3 C, the secondary discharge battery was measured for an intermediate discharge operating voltage when discharged at 2 C, and the results are also shown in Table 1 below. Furthermore, regarding the secondary batteries of Example 1 and Comparative Examples 1 and 2, the temperature of the wall surface of the container when externally short-circuited was measured, and the results are also shown in Table 1 below.

[0038]

[Table 1]

As is clear from Table 1, Example 1 in which the terminal portion of the sealing plate and the strip-shaped tab were fixed at two points by direct spot welding using two point electrodes provided with a moving distance adjusting mechanism and a pressure adjusting mechanism. It is understood that the secondary battery of No. 2 can fix the terminal portion of the sealing plate and the strip-shaped tab evenly and with high welding strength. In addition, the secondary battery of the example,
It can be seen that the battery voltage is higher than in Comparative Examples 1 and 2, and the temperature rise due to the abnormal current during an external short circuit can be suppressed.

On the other hand, similarly to the embodiment, a comparative example in which the terminal portion of the sealing plate and the strip-shaped tab are fixed at two points by using two point electrodes which are direct spot welding but have no moving distance adjusting mechanism. In No. 1, the contact between one of the two point electrodes and the strip-shaped tab was insufficient, so that the welding current fluctuated and splash occurred, resulting in low welding strength. On the other hand, when the terminal portion of the sealing plate and the strip tab are fixed at two points by series spot welding as in Comparative Example 2, the distance between the electrodes is reduced due to the narrow width of the strip tab and the reactive current increases. Weld strength was significantly reduced.

In addition, in the above-mentioned embodiment, the description is applied to the nickel-hydrogen secondary battery, but the present invention is also applicable to the nickel-cadmium secondary battery, the lithium battery and the lithium-ion secondary battery.

In the above-mentioned embodiment, an example applied to a cylindrical battery provided with a spiral electrode group produced by spirally winding a separator between a positive electrode having a strip tab and a negative electrode is described. However, the present invention can be similarly applied to a prismatic battery including an electrode group having a laminated structure produced by alternately stacking the positive electrode and the negative electrode with the separator interposed therebetween.

In the above embodiment, the strip-shaped tab having the lead portion is used, but a tab having no lead portion may be used. In the above embodiment, the number of connection points between the strip-shaped tab and the terminal portion of the sealing plate is two, but the number of connection points may be three, four, or more than two.

In the above embodiment, the explosion-proof mechanism is an elastic valve which is a return-type safety valve that opens when the gas pressure in the battery exceeds a predetermined value to release the gas to the outside, and then seals the battery again. Although the body is used, a valve membrane, which is a non-return type safety valve, may be used as the explosion-proof mechanism. The valve membrane may be arranged between the sealing plate and the positive electrode terminal so as to cover the gas vent hole of the sealing plate.

In the above-mentioned embodiment, the sealing plate having the structure in which the positive electrode terminal and the sealing plate are fixed by welding is used, but the sealing plate having the structure in which the sealing plate and the positive electrode terminal are integrated by caulking and fixing is used. Can be used.

In the above-described embodiment, an example in which the sealing plate having one pole terminal is applied to the battery having a structure in which it is attached to the opening of the container which also serves as the other pole terminal by caulking and fixing it through the insulating gasket is explained. Can be similarly applied to a battery having a structure in which is attached to the container by laser seam welding. In the battery having such a structure, a sealing plate having a hole in the center as the sealing plate, and a hermetically sealed plate made of glass so that both ends of the sealing plate protrude from the upper and lower surfaces of the sealing plate. What has a positive electrode pin terminal attached by a seal is used.
Therefore, when connecting the leading end of the strip-shaped tab and the terminal of the sealing plate, the supporting electrode is arranged on the sealing plate so that the recess surrounds the positive electrode pin terminal, and the supporting electrode is arranged. The tip of the positive electrode pin terminal projected on the surface opposite to the surface serves as the terminal portion of the sealing plate, and the tip portion of the strip-shaped tab is arranged on the terminal portion. After moving a plurality of point electrodes to the tip portion of the strip-shaped tab by a moving distance adjusting mechanism of a balance head for a distance corresponding to the unevenness of the tip portion and bringing them into contact with each other, the pressing mechanism uniformly applies to the plurality of point electrodes. Direct spot welding may be performed in which a welding current is applied between the support electrode and the plurality of point electrodes while applying pressure.

[0047]

As described above in detail, according to the method of manufacturing a battery of the present invention, the terminal portion of the sealing plate having the terminal and the tip end portion of the strip-shaped tab are connected at least at two positions evenly and with high welding strength. It is possible to improve battery characteristics such as battery voltage, suppress temperature rise at the time of external short circuit, and improve battery safety and reliability. Play.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a battery (for example, a cylindrical battery) manufactured by a method according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a sealing member having the explosion-proof function and the positive electrode terminal of FIG.

FIG. 3 is a partial sectional view showing a welding step of the manufacturing method according to the present invention.

FIG. 4 is a front view showing a welding step of the manufacturing method according to the present invention.

FIG. 5 is a plan view showing the arrangement of strip-shaped tabs in the welding process of the manufacturing method according to the present invention.

FIG. 6 is an enlarged cross-sectional view showing a sealing member having an explosion-proof function and a positive electrode terminal, which is used in an example according to the present invention.

FIG. 7 is a partial cross-sectional view showing a welding process of an example according to the present invention.

FIG. 8 is a partial cross-sectional view showing a welding process in Comparative Example 1.

9 is a partial cross-sectional view showing a welding process in Comparative Example 2. FIG.

[Explanation of symbols]

7 ... band-shaped tab, 10 ... insulating gasket, 12 ... sealing plate,
15 ... Positive electrode terminal, 16 ... Supporting electrode, 19b ... Point electrode.

Claims (1)

[Claims] 1. An electrode group produced by interposing a separator between one electrode having a strip-shaped tab and the other electrode and an electrolytic solution are housed in a container that also serves as the other electrode terminal, and the opening of the container is On the other hand, it is sealed with a sealing plate having a pole terminal,
In the method of manufacturing a battery having a structure in which the tip portion of the strip tab and the terminal portion of the sealing plate are connected at two or more points, the connection between the tip portion of the strip tab and the terminal portion of the sealing plate is the Using a supporting electrode for supporting the sealing plate, and a plurality of point electrodes having a moving distance adjusting mechanism for adjusting the moving distance according to the unevenness of the welding location and a pressure mechanism for pressurizing the welding location, The tip portion of the strip-shaped tab is arranged on the terminal portion of the sealing plate, the support electrode is arranged on a surface of the sealing plate opposite to the terminal portion, and the plurality of point electrodes are arranged on the tip portion of the strip-shaped tab. Is moved by the movement distance adjusting mechanism by a distance corresponding to the unevenness of the tip and brought into contact with the supporting electrode and the plurality of points while uniformly applying pressure to the plurality of point electrodes by the pressing mechanism. Between the electrodes A method for manufacturing a battery, which is performed by a method including a step of performing direct spot welding in which a welding current is passed.