JP2002289170A - Alkaline secondary battery - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an alkaline secondary battery that suppresses an internal short circuit during manufacturing and use, provides a high manufacturing yield, and is excellent in reliability and safety. SOLUTION: A positive electrode 15, a negative electrode 16, and a separator 17 including a lead 19 and an active material-containing mixture which are welded to at least a part of an end portion of a conductive substrate 18 along a winding direction.
The positive electrode 15, the negative electrode 16, and the separator 17 are spirally wound, and the lead welding end 24 of the positive electrode inner peripheral region excluding at least the positive electrode outermost peripheral region L on one spiral surface is formed. Protruding electrode group 14
A positive electrode current collector plate 26 welded to at least a part of the protruding lead welding end portion 24; and a container 11 accommodating at least the electrode group 14 and the positive electrode current collector 26 and also serving as a negative electrode terminal. It is characterized by having.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline secondary battery such as a nickel hydride secondary battery and a nickel cadmium secondary battery.

[0002]

2. Description of the Related Art A hydrogen storage alloy forms a negative electrode containing the same. When an electrode such as a nickel electrode is used as a counter electrode (positive electrode) in an alkaline electrolyte, hydrogen ions are occluded in the negative electrode during charging and during discharge. The occluded hydrogen ions are released from the negative electrode, and the released hydrogen ions are oxidized to return to water. For this reason, the hydrogen storage alloy is used as a negative electrode material of a secondary battery. As an example of such a secondary battery, a nickel-metal hydride secondary battery is known. This nickel hydrogen secondary battery has high energy density and volumetric efficiency, is friendly to the natural environment, and has high reliability.
A nickel-hydrogen secondary battery is a semi-permanent power supply because it can repeatedly secure or store power by a charging operation and drive (discharge) a load using the secured or stored power as a power source. It is widely put into practical use as an operating power supply for various equipment systems such as portable photographing machines. In recent years, as a substitute for a nickel cadmium secondary battery, it has been put to practical use as a power supply for a power tool or a hybrid vehicle that requires a large current discharge characteristic.

[0003] One of the typical constitutions employed in nickel-metal hydride secondary batteries is that a positive electrode and a negative electrode are placed in a container (battery outer can) also serving as a negative electrode terminal, and a separator is interposed therebetween to form a spiral. One having a configuration in which an electrode group having a wound structure is sealed is used. Specifically, a positive electrode containing an active material such as nickel hydroxide, and a negative electrode containing a hydrogen storage alloy are arranged in a separator therebetween and spirally wound to form an electrode group as an electromotive element. Make it. After accommodating the obtained electrode group in a container, injecting an alkaline electrolyte, connecting the electrode group to an external terminal, and closing the opening of the container to obtain a nickel-hydrogen secondary battery. .

In recent years, there has been a demand for higher output and further miniaturization of nickel-metal hydride secondary batteries used as power supplies for power tools and hybrid vehicles. To satisfy this demand, the positive electrode and the negative electrode have been thinned. To increase the number of turns of the spiral electrode group by making it long,
2. Description of the Related Art By electrically connecting a positive electrode and an external terminal via a positive electrode current collector plate, current collection of the positive electrode at two or more points has been performed.

The welding between the positive electrode current collector and the positive electrode is performed, for example, by projecting an end of the positive electrode from one of the spiral surfaces of the electrode group and welding the positive electrode current collector to the protruding end.

However, in a secondary battery provided with a positive electrode current collector plate, in the step of storing an electrode group for manufacturing a secondary battery in a container, the protruding positive electrode end comes into contact with the inner wall of the container also serving as a negative electrode terminal. As a result, there is a problem that an internal short circuit easily occurs and the yield is low. In addition, this secondary battery is inferior in safety because when the container is deformed by an impact due to dropping, vibration, or the like, the protruding positive end comes into contact with the inner wall of the container to cause an internal short circuit. In particular, when caulking is adopted as a method for sealing the container, the distance between the protruding positive electrode end and the inner wall of the container becomes short, so that an internal short circuit frequently occurs during manufacturing and during use.

Therefore, it has been practiced to arrange an insulating ring at least around the protruding positive electrode end to prevent contact between the protruding positive electrode end and the inner wall of the container.

[0008]

However, when the insulating ring is fitted to the protruding positive electrode end, the outermost part of the protruding positive electrode end is pushed outward by the insulating ring and comes into contact with the inner wall of the container. As a result, an internal short circuit occurs, and the production yield is further reduced. In addition, even if it does not come into contact with the inner wall of the container, the outermost peripheral portion of the positive electrode end is tilted toward the inner wall of the container due to the fitting of the insulating ring. If vibration is applied to the secondary battery or an impact is applied due to a drop or the like, the insulating ring is easily detached, and an internal short circuit occurs during use.

An object of the present invention is to provide an alkaline secondary battery which suppresses an internal short circuit during manufacturing and use, provides a high manufacturing yield, and is excellent in reliability and safety.

[0010]

According to the present invention, there is provided an alkaline secondary battery comprising: a conductive substrate; a lead welded to at least a part of an end of the conductive substrate along a winding direction; A positive electrode including an active material-containing mixture that is retained except for at least the lead welded end, including a negative electrode, and a separator disposed between the positive electrode and the negative electrode,
An electrode group in which the positive electrode, the negative electrode, and the separator are spirally wound, and the lead welding end of a positive electrode inner peripheral region excluding at least a positive electrode outermost peripheral region in one spiral surface protrudes in the spiral surface; And a positive electrode current collector plate welded to at least a part of the protruding lead welding end, and a container accommodating at least the electrode group and the positive electrode current collector and also serving as a negative electrode terminal. It is assumed that.

According to the present invention, a conductive substrate, a lead welded to at least a part of an end portion of the conductive substrate along a winding direction, and at least the lead welding end portion of the conductive substrate are removed. Positive electrode containing the active material-containing mixture that is held, and a negative electrode, comprising a separator disposed between the positive electrode and the negative electrode, the positive electrode, the negative electrode and the separator are spirally wound, and The lead welding end portion of the positive electrode inner peripheral region excluding at least the positive electrode outermost peripheral region in one spiral surface is welded to the electrode group protruding on the spiral surface and at least a part of the protruding lead welding end portion. A positive electrode current collector plate, having a bottomed cylindrical shape, an end of an opening is bent inward, and has a step portion having a shape protruding inward, at least the electrode group and the positive electrode current collector Stored A container that also serves as a negative electrode terminal, a sealing member disposed at an opening of the container, and a sealing member disposed on the step in the container and compressed by the bent portion at the opening of the container. And an insulating gasket for fixing the same.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of an alkaline secondary battery according to the present invention will be described.

[0013] The alkaline secondary battery comprises a conductive substrate, a lead welded to at least a part of an end of the conductive substrate along a winding direction, and at least the lead welded end of the conductive substrate. A positive electrode including the active material-containing mixture to be retained, a negative electrode, a separator disposed between the positive electrode and the negative electrode, the positive electrode, the negative electrode and the separator are spirally wound, and An electrode group in which the lead welded end of the positive electrode inner peripheral region excluding at least the positive electrode outermost peripheral region in the spiral surface protrudes, and a positive electrode current collector plate welded to at least a part of the protruded lead welded end. , An alkaline electrolyte, and a container that accommodates at least the electrode group, the positive electrode current collector, and the alkaline electrolyte and also serves as a negative electrode terminal.

Here, the outermost peripheral region of the positive electrode means one round from the end face of the winding end of the positive electrode as a starting point. FIG. 1 shows a cross-sectional view of an example of a spiral electrode group. The spiral electrode group 1 includes:
It is manufactured by spirally winding a positive electrode 2 and a negative electrode 3 with a separator 4 interposed therebetween. The outermost periphery of the electrode group 1 is the negative electrode 3. The outermost peripheral region of the positive electrode is one turn from the end face 5 at the end of winding, that is, from the end face 5 at the end of winding to a location indicated by a straight line 6.

Hereinafter, the positive electrode, the positive electrode current collector, the negative electrode, the separator, and the alkaline electrolyte will be described.

1) Positive Electrode The conductive substrate preferably has a three-dimensional porous structure. Examples of the conductive substrate having such a three-dimensional porous structure include a sintered metal fiber substrate, a substrate having a foamed shape, a substrate having a felt shape, and the like. The conductive substrate having a three-dimensional porous structure can be formed of, for example, nickel, stainless steel, or a nickel-plated metal.

It is preferable that at least the surface of the lead is formed of nickel. Examples of such a terminal plate include a nickel plate, a nickel-plated steel plate (NPS plate), and the like.

The shape of the lead can be, for example, an elongated shape such as a band shape or a ribbon shape.

As a method for welding the lead to the conductive substrate, for example, ultrasonic welding, spot welding, or laser irradiation welding can be adopted.

In order to protrude the lead welded end of the positive electrode inner peripheral region excluding at least the outermost positive electrode region on one spiral surface of the electrode group from the spiral surface, for example, the following (I) or (II) Can be adopted.

(I) Eliminate at least the lead welding end of the outermost region of the positive electrode.

(II) The width of at least the outermost peripheral area of the lead welding end of the positive electrode is reduced.

Examples of the active material include nickel hydroxide. As the nickel hydroxide, nickel hydroxide in which at least one metal selected from zinc and cobalt is eutectic, or non-eutectic nickel hydroxide can be used. 1 selected from zinc and cobalt
A positive electrode including nickel hydroxide in which more than one kind of metal is eutectic can improve charge efficiency and charge / discharge cycle characteristics in a high temperature state.

A conductive layer containing cobalt oxyhydroxide (CoOOH) can be formed on the surface of the nickel hydroxide.

The active material-containing layer may contain a binder. Examples of the binder include a fluorine-based resin such as polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), a polyacrylate (eg, sodium polyacrylate and potassium potassium acrylate), acrylic acid and vinyl Copolymer with alcohol,
A copolymer of acrylate and vinyl alcohol, a water-soluble cellulose derivative (for example, methyl cellulose (M
C), carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC)), polyacrylamide (PA), polyvinylpyrrolidone (PV
P), polyethylene oxide (PEO), PFD and the like. One or two or more kinds selected from the above-mentioned kinds can be used as such a binder.

The thickness of the positive electrode is preferably in the range of 0.3 mm to 0.4 mm.

2) Positive electrode current collector plate The positive electrode current collector plate is, for example, a nickel plate, a stainless steel plate,
It can be formed from a nickel-plated metal plate.

The shape of the positive electrode current collector plate is not particularly limited as long as the internal resistance of the secondary battery can be reduced, and may be, for example, a circular plate, an elliptical plate, a rectangular plate, or the like.

The positive electrode current collector preferably has a connection terminal for connection to an external positive terminal (for example, a sealing member having a positive terminal).

It is preferable that one or two or more projections are formed on the surface of the positive electrode current collector plate that faces the lead welding end. With such a configuration, the welding current can be concentrated on the protrusions during resistance welding, so that the welding strength between the positive electrode current collector and the lead welding end can be increased.

At least one gas vent hole can be formed in the positive electrode current collector plate. The shape of the vent hole can be, for example, circular, elliptical, rectangular or the like.

The thickness of the positive electrode current collector plate is preferably in the range of 0.15 to 2 mm.

3) Negative electrode The negative electrode includes a conductive substrate and a negative electrode mixture held on the conductive substrate and containing a hydrogen storage alloy. Also,
It is also possible to use a cadmium negative electrode instead of this negative electrode.

The hydrogen storage alloy is not particularly limited as long as it can store hydrogen electrochemically generated in an electrolytic solution and can easily release the stored hydrogen during discharge. . For example, LaNi ₅ , MmN
i ₅ (Mm is Misch metal enriched in Ce), LmNi
₅ (Lm is La-enriched misch metal), and part of Ni of these alloys is Al, Mn, Co, Ti, Cu, Zn,
Examples thereof include a multi-element-based material substituted with at least one element selected from Zr, Cr and B, a TiNi-based material, and a TiFe-based material. Among them, the general formula LmNi _w Co _x M
_ny Al _z (where Lm is at least one or more rare earth elements, and the total value of atomic ratios w, x, y and z is 5 ≦ w +
x + y + z ≦ 5.5) or a hydrogen storage alloy having the general formula AB _x (where A is Ti and / or Zr, and B is Mn, Ni, V, Co, C
r, Al, Fe, Cu, Mo, La, Ce, Pr and N
at least one element selected from the group consisting of
The atomic ratio x is represented by 1.8 ≦ x ≦ 2.5), and it is preferable to use a hydrogen storage alloy containing a C14 or C15 Laves phase as a main phase.

The negative electrode mixture may contain a binder. As the binder, one or more kinds selected from the polymers described for the positive electrode described above can be used.

It is desirable that the negative electrode mixture contains a conductive material. As the conductive material, for example, graphite, carbon black, or the like can be used.

Examples of the conductive substrate include a conductive substrate having a two-dimensional porous structure such as punched metal, expanded metal, and nickel net, and a three-dimensional porous material such as a felt-like metal porous body and a sponge-like metal porous body. And a conductive substrate having a porous structure.

The thickness of the negative electrode is preferably in the range of 0.2 mm to 0.3 mm.

4) Separator Examples of the separator include a nonwoven fabric made of a polyamide fiber, a nonwoven fabric made of a polyolefin fiber such as polyethylene and polypropylene, or a nonwoven fabric provided with a hydrophilic functional group.

The thickness of the separator is 0.1 mm to 0.1
It is preferable to set it within the range of 5 mm.

5) Alkaline Electrolyte Examples of the alkaline electrolyte include a potassium hydroxide (KOH) aqueous solution, a mixed solution of sodium hydroxide (NaOH) and lithium hydroxide (LiOH), potassium hydroxide (KOH) and LiOH Of KOH, LiOH and N
A mixed solution of aOH or the like can be used.

The alkaline secondary battery preferably further includes a negative electrode current collector plate from the viewpoint of lowering the internal resistance and further improving the high rate discharge characteristics. In this case, as the negative electrode, a conductive substrate having a two-dimensional porous structure,
Using a negative electrode mixture that is held except for at least the end portion along the winding direction of the conductive substrate, and projecting the negative electrode end surface on the mixture non-holding region side to the other spiral surface of the electrode group It is desirable to weld a negative electrode current collector plate to at least a part of the negative electrode end face. The conductive substrate in the mixture non-holding area is
It may be open or non-porous. Further, the negative electrode current collector plate is preferably brought into contact with the inner surface of the bottom of the container. At this time, the negative electrode current collector plate is preferably welded to the inner surface of the bottom of the container.

The negative electrode current collector plate can be formed of, for example, a nickel plate, a stainless steel plate, or a nickel-plated metal plate. The shape of the negative electrode current collector plate is not particularly limited as long as the internal resistance of the secondary battery can be reduced. For example, a circular plate, an elliptical plate, a rectangular plate, or the like can be used. Further, the thickness of the negative electrode current collector plate is preferably in the range of 0.15 to 2 mm.

One example of the alkaline secondary battery described above is shown in FIGS.

FIG. 2 is a longitudinal sectional view showing an example of the alkaline secondary battery according to the present invention, FIG. 3 is a plan view showing a positive electrode included in the alkaline secondary battery of FIG. 2, and FIG. FIG. 5 is a plan view for explaining a method for producing an electrode group in the alkaline secondary battery of FIG. 2, FIG. 5 is a plan view showing a positive electrode current collector plate with connection terminals included in the alkaline secondary battery of FIG. 2, and FIG. , FIG.
It is a perspective view which shows the principal part of the back surface of this positive electrode current collector plate.

The metal container 11 also serving as a negative electrode terminal has a cylindrical shape with a bottom, and has a bent portion 12 formed by bending the vicinity of the upper end of the opening inward, and an annular step having an inwardly projecting shape. A part 13. This container 11
For example, it is formed from steel whose surface is plated with nickel. An electrode group 14 is housed in the container 11. The electrode group 14 includes a strip-shaped positive electrode 15 and a strip-shaped negative electrode 16.
And a band-like separator 17 disposed between the band-like positive electrode 15 and the band-like negative electrode 16. The strip-shaped positive electrode 15 has a conductive substrate 18 in which the outermost peripheral region L of the positive electrode is cut out of one end along the winding direction, and an active portion held by the conductive substrate 18 except for the notched end. It includes a substance-containing mixture and a band-shaped lead 19 welded to one of the mixture non-holding regions. The mixture holding region of the positive electrode 15 is indicated by reference numeral 20. on the other hand,
The strip-shaped negative electrode 16 includes a conductive substrate 22 having a two-dimensional porous structure in which one end along the winding direction is a non-porous region (plain portion) 21, and a non-porous region 21 on both surfaces of the conductive substrate 22. And a layered negative electrode mixture 23 which is retained excluding. As shown in FIG. 3, the electrode group 14 has, at one end along the winding direction, an end to which the lead 19 of the positive electrode 15 is welded (hereinafter, referred to as a lead welded end 24) serving as the negative electrode 16 and the separator 17. And the other end of the negative electrode 16
The positive electrode 15 and the separator 1 are shifted in such a manner that the non-porous region 21 of the
It is manufactured by spirally winding the negative electrode 7 and the negative electrode 16. When producing the electrode group 14, it is preferable to wind the positive electrode 15 so that the lead 19 is located inside.

The non-porous region 21 of the negative electrode 16 of the electrode group 14
Are welded to, for example, a disk-shaped negative electrode current collector plate 25 (for example, made of nickel or steel whose surface is nickel-plated). After being stored in the container 11, the negative electrode current collector plate 25 is welded near its center to the bottom surface of the container 11.

As shown in FIG. 2 described above, the lead welded end 24 of the inner peripheral region of the positive electrode except for the outermost peripheral region 15 (L) of the positive electrode on one spiral surface of the electrode group 14 protrudes from the spiral surface. Or it is exposed.

As shown in FIG. 5, a disk-shaped positive current collector plate 2
6 has a band-shaped tab 27 as a connection terminal having a part of the peripheral edge extended in a band shape. Further, a gas vent hole 28 is opened at the center of the positive electrode current collector plate 26. further,
A plurality of grooves 29 are formed radially in the positive electrode current collector plate 26. As shown in FIG. 6, at least one surface of the positive electrode current collector 26 has a burr 30 (projection) formed around the groove 29 when the groove 29 is punched. The projecting surface of the burr 30 of the positive electrode current collector 26 is in contact with the end face of the lead welding end 24, and the lead welding end 2
A plurality of portions of the end surface of the positive electrode current collector plate 26 have burrs 30
Welded to. The strip-shaped tab 27 is folded back to the positive electrode current collector 26 side.

By the way, the alkaline electrolyte is filled in the container 1
1. It is a rectangular tube with a bottom and a hole 31 at the bottom.
The insulating gasket 32, which is open,
1 is disposed on the step 13. The insulating gasket 32 is formed of, for example, an insulating resin such as nylon or polypropylene. A circular sealing plate 33 as a sealing member having an explosion-proof function and a positive electrode terminal is housed in the insulating gasket 32. Circular sealing plate 3
3 has a gas vent hole 34 opened in the center,
A protruding positive terminal 35 disposed on the sealing plate 33 so as to surround the gas vent hole 34, and the gas vent hole 34 is closed in a space surrounded by the sealing plate 33 and the positive terminal 35. An elastic valve element 36 arranged in a compressed state. The positive electrode terminal 35 has a plurality of gas vent holes 37.
Is open. The insulating gasket 32 is compressed at the bent portion 12, and the sealing plate 33 is moved by the repulsive elastic force generated in the insulating gasket 32 by the compression.
Is fixed by caulking through an insulating gasket 32 in the opening. The tip of the strip tab 27 is welded to the lower surface of the sealing plate 33.

In FIGS. 2 to 6 described above, the negative electrode current collector plate 25 is connected to the end surface of the non-porous region 21 of the negative electrode 16. However, the present invention is not limited to this. May be connected to the end face of the non-porous region, and these strip-shaped conductive members may be connected to the inner surface of the container bottom by spot welding or the like.

In FIGS. 2 to 6 described above, the grooves 29 are provided in the positive electrode current collector plate 26. However, holes are opened instead of the grooves, and burrs around the holes are used as the projections 30. Can be.

Further, in FIGS. 2 to 6 described above, the example of the above (I) in which the lead welding end of the outermost peripheral region L of the positive electrode is deleted has been described. As described in (II), the width (width in the direction orthogonal to the winding direction) of the lead welded end portion of the outermost peripheral region L of the positive electrode may be narrower than the inner peripheral region of the positive electrode.

According to the alkaline secondary battery described above,
At least one of the spiral surfaces of the electrode group has a protruding lead welding end in the inner peripheral region of the positive electrode except for the outermost peripheral region of the positive electrode. And a sufficient distance between the container and the inner wall of the container. As a result, when the electrode group is stored in the container for manufacturing the secondary battery, the lead welding end does not contact the inner wall of the container, so that an internal short circuit can be prevented, and a high manufacturing yield can be obtained. In addition, even if the container is deformed due to impact such as dropping or vibration applied to the secondary battery, since the lead welded end does not contact the inner wall of the container, an internal short circuit can be prevented. Safety can be improved. Therefore, it is possible to prevent an internal short circuit during the use of the secondary battery without using the insulating ring, and at the same time, it is possible to simplify the manufacturing process as compared with the case where the insulating ring is used, and The rate of occurrence of insulation failure can be reduced.

Further, this nickel-hydrogen secondary battery can realize excellent large-current discharge characteristics.

That is, welding of the positive electrode current collector to the lead welding end is performed by resistance welding in a state where the electrode group is housed in the container. Therefore, when the lead welding end portion of the outermost region of the positive electrode is projected and the positive electrode current collector is to be welded to this location, the welding electrode comes into contact with the inner wall of the container, and the container and the positive electrode current collector are welded. Poor welding is likely to occur. In order to avoid such poor welding, the lead welding end in the outermost peripheral region of the positive electrode is not originally welded to the positive electrode current collector plate, and is a portion that does not affect the current collection. Therefore, the current collecting efficiency of the positive electrode is not impaired without protruding the lead welding end portion of the outermost peripheral region of the positive electrode, and excellent large current discharge characteristics can be secured.

[0057]

Embodiments of the present invention will be described below in detail with reference to the drawings and FIGS.

FIG. 7 is a plan view showing a positive electrode included in a nickel hydride secondary battery of a comparative example, and FIG. 8 is a longitudinal sectional view showing a nickel hydride secondary battery of a comparative example.

(Example) <Preparation of paste-type positive electrode> Nickel hydroxide powder 60 parts by mass, nickel oxyhydroxide 20 parts by mass, nickel powder 1
0.4% by weight of carboxymethylcellulose (CMC) in a mixture containing 0 parts by weight and 10 parts by weight of cobalt powder
An aqueous solution was added and kneaded to prepare a paste.

On the other hand, a foamed nickel porous body having a porosity of 97% and a thickness of 1.5 mm was prepared as a conductive substrate having a three-dimensional porous structure, and the end face at one end along the longitudinal direction was prepared. 0.7mm thickness up to 2mm inside area
mm to form a low porosity region. A portion corresponding to the positive electrode outermost peripheral region L in the low porosity region was deleted by cutting.

The obtained paste was filled in a porous nickel body, dried and pressed to obtain an active material-containing mixture holding substrate. After cutting this mixture holding substrate into a strip,
The mixture held in the low porosity region was removed by ultrasonic vibration to provide a conductive substrate exposed region. A band-shaped lead 19 having a width of 2 mm was formed on one conductive substrate exposed area.
Then, a nickel plate having a thickness of 0.02 mm was welded to obtain a positive electrode 15 having a thickness of 0.3 mm.

<Preparation of Paste Type Negative Electrode> The composition passed through a 200-mesh sieve was LmNi _4.2 Co _0.2 Mn _0.3 Al
_For 100 parts by mass of the hydrogen storage alloy powder represented by _0.3 , 0.5 parts by mass of sodium polyacrylate, 0.125 parts by mass of carboxymethyl cellulose (CMC), 1.5 parts by mass of a dispersion of polytetrafluoroethylene, and carbon black One part by mass was added and kneaded with water to prepare a paste. This paste is applied to both surfaces of a punched metal as a conductive substrate having a non-porous region (uncoated portion) at one end on the longitudinal direction, dried, and then roll-formed by a roller press to form a negative electrode mixture holding substrate. Obtained. The negative electrode 16 having a thickness of 0.25 mm was produced by removing the negative electrode mixture 23 at a portion having a width of 2 mm at one end along the longitudinal direction of the mixture holding substrate to expose the non-porous region 21.

Next, as shown in FIG. 3, the thickness of the cathode 15, the anode 16, and the separator 17 is 0.1
A lead-welded end 24 of the positive electrode 15 is connected to the negative electrode 16 at one end along the winding direction by using a 2 mm polyamide nonwoven fabric.
And the non-porous region 21 of the negative electrode 16 at the other end protrudes as compared with the positive electrode 15 and the separator 17 and is stacked so as to be shifted from each other,
The electrode group 14 was produced by spirally winding this laminate.

In the obtained electrode group 14, the lead welding end does not exist in the outermost peripheral region 15 (L) of the positive electrode on one spiral surface, and the inner peripheral region excluding the outermost peripheral region 15 (L) of the positive electrode. The lead welded end 24 of the region was projected or exposed on the spiral surface.

Subsequently, a disk-shaped negative electrode current collector plate 25 is provided at a plurality of positions on the end face of the non-porous region 21 of the negative electrode 16 of the electrode group 14.
Was spot welded. After storing such an electrode group 14 in the bottomed cylindrical container 11, the vicinity of the center of the negative electrode current collector plate 25 was spot-welded to the bottom inner surface of the container 11. A positive current collector plate 26 having a strip-shaped terminal 27 is disposed on the lead welding end 24 of the electrode group 14 such that the projecting surface of the burr 30 contacts the lead welding end 24. Eight spots of the lead welded ends 24 were spot-welded to the burrs 30 of the plate 26.

Thereafter, an alkaline electrolyte containing potassium hydroxide as a main component was accommodated. Next, the step 1 in the container 11
3, an insulating gasket 32 in which a sealing member having an explosion-proof function and a positive electrode terminal is accommodated is arranged. After the diameter of the opening of the container 11 is reduced, the end of the opening is bent inward. The above-mentioned FIG. 2 is secured by caulking and fixing a sealing member to the opening portion of FIG.
A 4/5 A cylindrical nickel-metal hydride secondary battery having the structure shown in FIG.

(Comparative Example) A positive electrode 40 having a structure shown in FIG. 7 was produced in the same manner as in the above-described embodiment, except that the strip-shaped lead 19 was welded to the entire end of the conductive substrate 18 along the winding direction. did.

Next, the positive electrode 40, the negative electrode 16 similar to that described in the above-described embodiment, and the separator 17 similar to that described in the above-described embodiment are connected to the positive electrode 40 at one end along the winding direction. The lead welding end 41 protrudes compared to the negative electrode 16 and the separator 17, and the non-porous region 21 of the negative electrode 16 protrudes compared to the positive electrode 40 and the separator 17 at the other end. The electrode group 42 was produced by spirally winding the laminate.

In the obtained electrode group 42, the lead welded end 41 of the entire positive electrode 40 protruded or exposed on one spiral surface.

Subsequently, a disc-shaped negative electrode current collector plate 25 is provided at a plurality of positions on the end face of the non-porous region 21 of the negative electrode 16 of the electrode group 42.
Was spot welded. After such an electrode group 42 was housed in the bottomed cylindrical container 11, the vicinity of the center of the negative electrode current collector 25 was spot-welded to the bottom inner surface of the container 11. Further, a positive electrode current collector plate 26 having a strip-shaped terminal 27 is disposed on the lead welded end 41 of the electrode group 42 such that the projecting surface of the burr 30 contacts the lead welded end 41. Eight spots in the inner peripheral portion of the burr 30 of the plate 26 excluding the outermost periphery of the lead welding end 41 were spot-welded.

An insulating ring 44 having one open end 43 bent inward was prepared. The insulating ring 44 was inserted between the outermost periphery of the lead welding end 41 and the inner peripheral surface of the container 11 and between the peripheral surface of the positive electrode current collector 26 and the inner peripheral surface of the container 11.

Next, an alkaline electrolyte having the same composition as that described in the above-mentioned embodiment was accommodated. Then, container 1
1, an insulating gasket 32 in which a sealing member having an explosion-proof function and a positive electrode terminal is accommodated is arranged on the step portion 13;
After reducing the diameter of the opening of the container 11, the end of the opening is bent inward to fix the sealing member to the opening of the container 11 via the insulating gasket 32 to fix the structure shown in FIG. A 4/5 A size cylindrical nickel-metal hydride secondary battery was assembled.

For the secondary batteries of Examples and Comparative Examples, a DC voltage of 500 V was applied between the positive electrode and the negative electrode before the negative electrode current collector was welded to the inner surface of the container bottom after the electrode group was housed in the container. The insulation resistance between the positive and negative electrodes at that time was measured, and those having a resistance value equal to or less than a predetermined value were regarded as having insulation failure, and the number thereof was measured to evaluate the insulation failure rate. The results are shown in Table 1 below.

Further, with respect to the secondary battery of the comparative example, after inserting and arranging the insulating ring, before storing the alkaline electrolyte,
A DC voltage of 500 V is applied between the positive electrode and the negative electrode, and the insulation resistance between the positive and negative electrodes at that time is measured. The insulation failure rate was evaluated. The results are shown in Table 1 below.

Further, with respect to the secondary batteries of Examples and Comparative Examples, each secondary battery was freely dropped three times from a height of 75 cm onto hardwood, and then a DC voltage of 500 V was applied between the positive terminal and the negative terminal. Was applied, the insulation resistance between the positive and negative terminals at that time was measured, and those having a resistance value equal to or less than a predetermined value were regarded as having insulation failure, the number thereof was measured, and the insulation failure rate was evaluated. The results are shown in Table 1 below.

[0076]

[Table 1]

As is clear from Table 1, the secondary batteries of the examples have no insulation failure both in the case where the electrode group is housed in the container and in the drop test. On the other hand, in the secondary battery of the comparative example, it can be seen that insulation failure occurs in both steps when the electrode group is housed in the container and when the insulating ring is inserted.

The secondary batteries of Examples and Comparative Examples were charged at 1 C for 1.2 hours, paused for 30 minutes, and then discharged to 1.0 V at 15 C. It was confirmed that a large current discharge capacity comparable to that of the comparative example was obtained.

[0079]

As described above, according to the alkaline secondary battery of the present invention, the manufacturing process can be simplified without impairing the charge / discharge characteristics such as the large current discharge characteristics, and the manufacturing yield can be reduced. It has a remarkable effect that it can be increased and reliability and safety can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a spiral electrode group.

FIG. 2 is a longitudinal sectional view showing an example of the alkaline secondary battery according to the present invention.

FIG. 3 is a plan view showing a positive electrode included in the alkaline secondary battery of FIG. 2;

FIG. 4 is a plan view for explaining a method of manufacturing an electrode group in the alkaline secondary battery of FIG. 2;

FIG. 5 is a plan view showing a positive electrode current collector plate with connection terminals included in the alkaline secondary battery of FIG. 2;

FIG. 6 is a perspective view showing a main part on the back surface of the positive electrode current collector plate of FIG. 5;

FIG. 7 is a plan view showing a positive electrode included in a nickel-hydrogen secondary battery of a comparative example.

FIG. 8 is a longitudinal sectional view showing a nickel-metal hydride secondary battery of a comparative example.

[Description of Signs] 11 ... container, 14 ... electrode group, 15 ... positive electrode, 16 ... negative electrode, 17 ... separator, 18 ... conductive substrate, 19 ... lead, 20 ... mixture holding area, 21 ... non-porous area, 22 ... Conductive substrate, 23 ... Negative electrode mixture, 24 ... Lead welded end, 26 ... Positive electrode current collector, 27 ... Tab, 33 ... Sealing plate.

Claims (2)

[Claims] 1. A conductive substrate, a lead welded to at least a part of an end of the conductive substrate along a winding direction, and an active material held on the conductive substrate except for at least the lead welded end. Positive electrode containing the mixture, comprising a negative electrode, a separator disposed between the positive electrode and the negative electrode, the positive electrode, the negative electrode and the separator are spirally wound, and at least one of the spiral surface An electrode group in which the lead weld end of the positive electrode inner peripheral region excluding the positive electrode outermost peripheral region protrudes on the spiral surface; and a positive electrode current collector plate welded to at least a part of the protruded lead weld end, An alkaline secondary battery, comprising: a container accommodating at least the electrode group and the positive electrode current collector and also serving as a negative electrode terminal. 2. The positive electrode according to claim 1, wherein the lead welding end does not exist at least in the outermost peripheral region, or at least the width of the lead welding end in the outermost peripheral region is narrow. Item 7. The alkaline secondary battery according to Item 1.