JP2016149300A - Alkaline secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline secondary battery which has further excellent high rate discharge characteristics.SOLUTION: A nickel hydrogen secondary battery 1 includes: an outer package 2; a sealing body 14 to which a positive electrode terminal 22 is electrically connected and which seals an opening of the outer package 2; an electrode group 4 which is formed by overlapping and spirally winding a positive electrode 6 and a negative electrode 8 via a separator 10 and housed in the outer package 2 together with an alkaline electrolyte; and a positive electrode current collector 28 which is arranged and installed between the sealing body 14 and the electrode group 4 and energizes the positive electrode terminal 22 and the positive electrode 6. The positive electrode current collector 28 has a connection plate 27. The electrode group 4 has a protrusion end edge 32 which is the end edge of the positive electrode 6 opposed to the connection plate 27 and protruding to the connection plate 27 side. The protrusion end edge 32 includes a connection piece 50, which is bent toward the radial outside of the electrode group, at the tip. The connection piece 50 and the connection plate 27 are joined to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alkaline secondary battery.

  A cylindrical nickel-hydrogen secondary battery is known as a kind of alkaline secondary battery. In this nickel-metal hydride secondary battery, an electrode group formed by spirally winding a positive electrode and a negative electrode that are stacked with a separator sandwiched between them is placed on a bottomed cylindrical outer can containing an alkaline electrolyte. The upper end opening of the outer can is formed by being sealed with a cover plate electrically connected to the positive terminal.

  Here, a strip-like positive electrode lead is used for electrical connection between the positive electrode and the positive electrode terminal. Specifically, one end of the positive electrode lead is joined to a part of the positive electrode, and the other end of the positive electrode lead is joined to the cover plate, whereby the positive electrode and the positive electrode terminal are electrically connected.

  The above-mentioned nickel metal hydride secondary battery is used in various devices such as portable electronic devices, power tools, and hybrid electric vehicles because it has a higher capacity and better environmental safety than nickel cadmium secondary batteries. The use is expanding. As the applications are expanding in this way, higher performance is desired for nickel-hydrogen secondary batteries, and in particular, high-rate discharge characteristics can be improved so that large currents can be output efficiently. It is desired.

  In order to improve the high rate discharge characteristics, it is necessary to make the internal resistance of the battery as low as possible. Therefore, in order to reduce the internal resistance of the battery, measures are taken to electrically connect the positive electrode and the positive electrode terminal with a positive electrode current collector interposed therebetween. As a battery including such a positive electrode current collector, for example, a battery disclosed in Patent Document 1 is known.

  In the manufacturing process of the battery represented by Patent Document 1, first, when forming the electrode group, the upper end edge of the positive electrode is arranged and wound so as to protrude from the upper end edge of the negative electrode. The edge of the positive electrode is projected in a spiral shape. The protruding edge portion of the positive electrode is hereinafter referred to as a protruding edge portion. On the other hand, a positive electrode current collector provided with a circular connection disk and a strip-shaped connection ribbon formed integrally with the connection disk is prepared. In this positive electrode current collector, the connection disk is bonded to the protruding end edge of the positive electrode, and the connection ribbon is bonded to the lid plate. Thereby, the positive electrode and the positive electrode terminal are electrically connected via the positive electrode current collector and the lid plate.

  In this positive electrode current collector, the connection disk is in contact with the protruding edge of the positive electrode over a wide range. That is, compared with the conventional nickel-hydrogen secondary battery in which the positive electrode lead is in contact with the positive electrode only in a range corresponding to its width, the battery of Patent Document 1 is in contact with the positive electrode in a range wider than the width of the positive electrode lead. A positive electrode current collector. For this reason, the battery of patent document 1 becomes low in internal resistance of a battery compared with the conventional nickel hydride secondary battery. As a result, the high rate discharge characteristic of the battery of Patent Document 1 is improved.

JP-A 63-4562

  By the way, in the various devices as described above, power consumption has increased in recent years, and accordingly, nickel hydride secondary batteries mounted on these devices are required to be discharged at a higher rate. .

  However, the nickel metal hydride secondary battery of Patent Document 1 does not sufficiently meet the above-described requirements, and further improvement in high-rate discharge characteristics is required.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide an alkaline secondary battery with higher high-rate discharge characteristics.

  In order to achieve the above object, according to the present invention, a bottomed cylindrical outer can including a negative electrode terminal and a seal in which a positive electrode terminal is electrically connected to seal the upper end opening of the outer can A cylindrical electrode group which is formed by winding a body, a positive electrode and a negative electrode over a separator and wound in a spiral, and is housed together with an alkaline electrolyte in the outer can, and the sealing body and the electrode group A positive electrode current collector that is disposed between the positive electrode terminal and the positive electrode, and the positive electrode current collector has a metal connection plate, and the electrode group includes the connection plate The edge of the positive electrode facing the electrode has a protruding edge that protrudes toward the connecting plate, and the protruding edge is bent at the tip thereof toward the radially outer side of the electrode group. Includes a piece, and the bent piece and the connection plate are joined together Alkaline secondary battery is provided.

  Preferably, four or more bent pieces are provided per circumference of the wound positive electrode.

  Further, it is preferable that the bent piece is positioned at a portion of the protruding end edge portion excluding the outermost peripheral portion of the positive electrode.

  More preferably, the length of the bent piece extending radially outward of the electrode group is S, the thickness of the positive electrode is t1, the thickness of the separator is t2, and the thickness of the negative electrode is t3. When the total thickness of these t1, t2, and t3 is T, the structure satisfies the relationship of S <T.

  In the alkaline secondary battery according to the present invention, the protruding edge portion of the positive electrode includes a bent piece, and the bent piece is joined to the connection plate of the positive electrode current collector. The contact area is larger than before. Thereby, the internal resistance of the battery is lower than before, and the high rate discharge characteristics of the battery are improved.

1 is a partial cross-sectional view showing a cylindrical nickel-metal hydride secondary battery according to the present invention. It is the top view shown roughly in the state which expand | deployed the positive electrode integrated in the nickel-hydrogen secondary battery of FIG. It is a top view of a connection piece. It is a top view of the intermediate product of a positive electrode. It is the top view which showed the upper part of the electrode group roughly. It is a top view of a positive electrode collector. It is the top view which showed roughly the state by which the positive electrode electrical power collector (it shows with the virtual line) was piled up on the upper part of the electrode group.

Hereinafter, an alkaline secondary battery according to the present invention will be described with reference to the drawings.
As an alkaline secondary battery according to an embodiment to which the present invention is applied, an AA size cylindrical nickel-hydrogen secondary battery (hereinafter referred to as a battery) 1 shown in FIG. 1 will be described as an example.

  As shown in FIG. 1, the battery 1 includes an outer can 2 having a bottomed cylindrical shape with an open upper end. The outer can 2 has conductivity, and the bottom wall functions as a negative electrode terminal. In the outer can 2, an electrode group 4 is accommodated together with a predetermined amount of an alkaline electrolyte (not shown).

  The opening 3 of the outer can 2 is closed by a sealing body 14. The sealing body 14 includes a disc-shaped lid plate 16 having conductivity, a valve body 20 disposed on the lid plate 16, and a positive electrode terminal 22. A ring-shaped insulating packing 18 is disposed on the outer periphery of the cover plate 16 so as to surround the cover plate 16. The insulating packing 18 and the cover plate 16 are formed by caulking the opening edge 17 of the outer can 2. 2 is fixed to the opening edge 17. That is, the lid plate 16 and the insulating packing 18 cooperate with each other to seal the opening 3 of the outer can 2. Here, the lid plate 16 has a central through hole 19 in the center, and a rubber valve body 20 is disposed on the outer surface of the lid plate 16 so as to close the central through hole 19. Furthermore, a flanged cylindrical positive terminal 22 is electrically connected to the outer surface of the cover plate 16 so as to cover the valve body 20. The positive terminal 20 presses the valve body 18 toward the cover plate 16. Further, the positive electrode terminal 22 has a gas vent hole 23 on a side surface.

  Normally, the central through hole 19 is airtightly closed by the valve body 20. On the other hand, if gas is generated in the outer can 2 and its internal pressure increases, the valve body 20 is compressed by the internal pressure, and the central through hole 19 is opened. As a result, gas is released from the outer can 2 to the outside through the central through hole 19 and the gas vent hole 23 of the positive terminal 22. That is, the central through hole 19, the valve body 20, and the gas vent hole 23 of the positive electrode terminal 22 form a safety valve for the battery 1.

  The electrode group 4 includes a strip-like positive electrode 6, a negative electrode 8, and a separator 10, which are wound in a spiral shape with the separator 10 sandwiched between the positive electrode 6 and the negative electrode 8. That is, the positive electrode 6 and the negative electrode 8 are overlapped with each other via the separator 10. Such an electrode group 4 has a cylindrical shape as a whole.

  The alkaline electrolyte injected into the outer can 2 is held in the electrode group 4, and most of the alkaline electrolyte is held in the separator 10. And charging / discharging reaction advances between the positive electrode 6 and the negative electrode 8 through this alkaline electrolyte.

  The negative electrode 8 has a conductive negative electrode core having a strip shape, and a negative electrode mixture is held in the negative electrode core.

  The negative electrode core is made of a band-shaped metal material in which a large number of through holes (not shown) penetrating in the thickness direction are distributed. For example, a punching metal sheet can be used as such a negative electrode core.

  The negative electrode mixture is not only filled in the through hole of the negative electrode core, but also held in layers on both surfaces of the negative electrode core.

  The negative electrode mixture includes particles of a hydrogen storage alloy, a conductive material, a binder, and the like. Here, the hydrogen storage alloy is an alloy capable of storing and releasing hydrogen, which is a negative electrode active material, and a hydrogen storage alloy generally used in nickel-hydrogen secondary batteries is preferably used. The above-described binder serves to bind the particles of the hydrogen storage alloy and the conductive material to each other and at the same time bind the negative electrode mixture to the negative electrode core. Here, as the conductive material and the binder, those generally used in nickel-hydrogen secondary batteries are preferably used.

Moreover, the negative electrode 8 can be manufactured as follows, for example.
First, a slurry of a negative electrode mixture is prepared by kneading a hydrogen storage alloy powder composed of hydrogen storage alloy particles, a conductive material, a binder, and water. The obtained negative electrode mixture slurry is applied to the negative electrode core and dried. After drying, the negative electrode core body to which the negative electrode mixture containing hydrogen storage alloy particles and the like is attached is subjected to roll rolling and cutting, whereby the negative electrode 8 is obtained.

Next, the positive electrode 6 will be described.
The positive electrode 6 includes a conductive positive electrode base material having a porous structure and having a large number of pores, and a positive electrode mixture held in the pores and on the surface of the positive electrode base material.

  As the positive electrode base material, for example, foamed nickel (nickel foam) can be used.

  The positive electrode mixture includes nickel hydroxide particles as positive electrode active material particles, a cobalt compound as a conductive agent, a binder, and the like.

  As is clear from FIG. 1, the positive electrode 6 has a part of the positive electrode 6 protruding from the adjacent negative electrode 8 on the upper end side of the electrode group 4. Hereinafter, this protruding portion is referred to as a protruding end edge portion 32. The protruding end edge 32 of the positive electrode 6 protrudes in a spiral shape on the upper end side of the electrode group 4. Here, the shape of the positive electrode 6 will be described in more detail below.

  As shown in FIG. 2, the positive electrode 6 has a substantially rectangular shape as a whole, as shown in FIG. 2, and is positioned above the main body 40 and a main body 40 that overlaps the negative electrode 8. Projecting end edge 32. The main body portion 40 is filled with a positive electrode mixture. On the other hand, the positive electrode mixture is removed in advance at the protruding edge portion 32, and the positive electrode mixture is not filled in the protruding edge portion 32. The protruding end edge portion 32 is compressed in the thickness direction and is slightly thinner than the main body portion 40. Further, the protruding end edge portion 32 includes a base end region 42 located on the main body portion 40 side and a front end region 44 located on the opposite side of the base end region 42 from the main body portion 40. In FIG. 2, reference numeral 52 indicates the winding start end portion of the positive electrode 6, and reference numeral 54 indicates the winding end end portion of the positive electrode 6. When the positive electrode 6 is incorporated into the electrode group 4, the winding start end portion 52 side is located on the radially inner side of the electrode group 4, and the winding end end portion 54 side is located on the radially outer side of the electrode group 4.

  In the tip region 44 described above, a range corresponding to the outermost circumference of the positive electrode 6 when wound (a range indicated by a reference sign V in FIG. 2, hereinafter referred to as an outermost peripheral range) is cut out. ing. That is, in the longitudinal direction of the positive electrode 6 (the direction of the arrow x in FIG. 2), the tip region 44 of the protruding end edge portion 32 is a portion excluding the outermost peripheral range V described above, that is, the electrode beyond the outermost peripheral range V. It exists only in the range to be positioned on the radially inner side of the group 4 (the range indicated by the reference symbol W in FIG. 2, hereinafter referred to as the inner peripheral range).

  Here, the length of the tip region 44 in the direction indicated by the arrow y in FIG. 2 (hereinafter referred to as the y direction) is defined as S.

  Furthermore, a plurality of cuts 46 are formed in the tip region 44 in parallel in the direction along the y direction. The lengths of these notches 44 in the y direction are the same as S.

  The distal end region 44 is bent along a virtual boundary line 48 that is hypothesized at the boundary with the proximal end region 42, and serves as a connection piece (bending piece) 50 connected to the positive electrode current collector 28 described later. Specifically, as shown in FIG. 1, the connection piece 50 is formed by bending the tip region 44 at the protruding end edge 32 of the positive electrode 6 toward the radially outer side of the electrode group 4 at approximately 90 degrees. Is done. As shown in FIG. 3, the connecting piece 50 has a rectangular shape, and the length of the first side 61 and the second side 62 corresponding to the notch 46 is the same as the length of the notch 46. S. The length of the third side 63 corresponding to the virtual boundary line 48 and the length of the fourth side 64 facing the third side 63 corresponds to the length between the notches 46 adjacent to each other and is defined as U. To do.

The positive electrode 6 can be manufactured as follows, for example.
First, a positive electrode mixture slurry containing a positive electrode active material powder composed of positive electrode active material particles, a conductive material, water, and a binder is prepared. The obtained positive electrode mixture slurry is filled in, for example, nickel foam and dried. After drying, the nickel foam filled with nickel hydroxide particles and the like is rolled and then cut. Thereby, the intermediate product 70 of the positive electrode 6 holding the positive electrode mixture is obtained.

  As shown in FIG. 4, the intermediate product 70 has a rectangular shape as a whole. Then, the positive electrode mixture is removed from the upper edge 72 of the intermediate product 70, and the positive electrode base material is exposed. Here, the method for removing the positive electrode mixture is not particularly limited, but for example, it is suitably performed by applying ultrasonic vibration. The main body 40, which is a region other than the upper edge 72, is still filled with the positive electrode mixture.

  Next, the upper end edge portion 72 from which the positive electrode mixture has been removed is compressed in the thickness direction of the intermediate product 70 to become the protruding end edge portion 32. Since the positive electrode base material is in a dense state by being compressed in this way, the protruding end edge portion 32 is easily welded.

  Thereafter, the outermost peripheral range V is cut out in the front end region 44 at the protruding end edge 32 so that the front end region 44 exists only in the inner peripheral range W. Further, a plurality of cuts 46 having a length S in the direction along the y direction are made in parallel in the remaining tip region 44. At this time, it is preferable to make the cuts 46 at equal intervals. Thereby, the positive electrode 6 as shown in FIG. 2 is obtained.

  Next, as the separator 10, for example, a polyamide fiber nonwoven fabric provided with a hydrophilic functional group, or a polyolefin fiber nonwoven fabric such as polyethylene or polypropylene provided with a hydrophilic functional group can be used.

  The positive electrode 6 and the negative electrode 8 produced as described above are spirally wound with the separator 10 interposed therebetween, whereby the electrode group 4 is formed. Specifically, during winding, the positive electrode 6 and the negative electrode 8 are arranged slightly shifted from each other in the direction along the axial direction of the electrode group 4, and a predetermined size is provided between the positive electrode 6 and the negative electrode 8. The separator 10 is disposed at a predetermined position, and the winding work is performed in this state. As a result, a cylindrical electrode group 4 as shown in FIG. 1 is obtained. As an aspect of the obtained electrode group 4, the protruding end edge 32 of the positive electrode 6 protrudes from the adjacent negative electrode 8 on one end side (the upper side in FIG. 1) of the electrode group 4. The electrode group 4 is formed by winding the positive electrode 6, the negative electrode 8, and the separator 10 with a core having a predetermined outer diameter, and the core is extracted after the winding operation. A through hole 9 is formed in the center of the electrode group 4.

  At the protruding edge portion 32 of the positive electrode 6, the tip region 44 is bent to form the connection piece 50 prior to or during the winding operation. Since a plurality of cuts 46 are formed in the tip region 44, the connection piece 50 spreads radially outward in the radial direction of the electrode group 4. For this reason, winding work can be performed smoothly. Note that the length of the connection piece 50 extending outward in the radial direction of the electrode group 4 is S.

  Here, it is preferable that four or more connection pieces 50 are included per circumference of the positive electrode 6 wound in the electrode group 4. When the number of connection pieces 50 is 4 or less, the positive electrode is difficult to wind, and the winding operation described above cannot be performed smoothly. The number of connection pieces 50 is four or more, and it is preferable that the number of connection pieces 50 is as large as possible because the winding operation is facilitated. Since the number of connection pieces 50 depends on the number of cuts 46, it is preferable to set the length U between the cuts 46 to an appropriate length.

  Further, as shown in FIGS. 1 and 5, the thickness of the positive electrode 6 is t1, the thickness of the separator 10 is t2, and the thickness of the negative electrode 8 is t3. The total thickness of these t1, t2, and t3 (t1 + t2 + t3) When the thickness is T, the relationship with the length S of the connection piece 50 preferably satisfies the relationship S <T. If the length S of the connecting piece 50 is too long, the connecting piece 50 and the negative electrode 8 may come into contact with each other due to vibration or the like, causing an internal short circuit. Therefore, if the length S of the connection piece 50 is set to a value smaller than the total thickness T of the thickness t1 of the positive electrode 6, the thickness t2 of the separator 10, and the thickness t3 of the negative electrode 8, the connection piece 50 Since possibility that 50 may contact with the negative electrode 8 which adjoins can be made lower, it is preferable. Since the separator 10 is thin, it is difficult to see in FIG. 5, so the illustration of the separator 10 is omitted.

  In the electrode group 4 as described above, the positive electrode current collector 28 is connected to one end side (upper side in FIG. 1).

Here, the positive electrode current collector 28 will be described.
The positive electrode current collector 28 is entirely made of a conductive material, and includes a plate-like connection plate 27 and a belt-like positive electrode ribbon 26 formed integrally with the connection plate 27.

  The connection plate 27 is a component joined to the positive electrode 6 protruding from the upper end of the electrode group 4. The shape of the connection plate 27 in plan view is not particularly limited, and an arbitrary shape such as a disk shape or a polygonal shape can be adopted. Further, the size of the connection plate 27 is set to a size that is smaller than the outer diameter of the electrode group 4 and can cover the positive electrode 6 protruding from the upper end of the electrode group 4.

  In the present embodiment, a substantially pentagonal plate material is used as the connection plate 27 as shown in FIG. Specifically, the connection plate 27 is a thin plate made of stainless steel having a substantially pentagonal shape as a whole, a circular central through hole 29 at the center, and five slits 30 extending radially so as to surround the central through hole 29. Is included. The central through hole 29 substantially coincides with the through hole 9 of the electrode group 4. An alkaline electrolyte is supplied to the electrode group 4 through the central through hole 29. Further, when the plurality of slits 30 are provided in the connection plate 27, the flat plate portion 31 that is a region sandwiched between the slits 30 is easy to move. For this reason, even when the electrode group 4 has some winding deviation and the protruding end edge portion 32 of the positive electrode 6 has a vertical distortion, the flat plate portion 31 of the connection plate 27 can follow the distortion. The occurrence of defects can be suppressed. Moreover, it is preferable that the slit 30 is formed by punching to generate a burr extending downward (on the electrode group 4 side) at the edge portion of the slit 30.

  The positive electrode ribbon 26 extends from one side of the five sides of the pentagon in the connection plate 27.

  In the positive electrode current collector 28 as described above, the connection plate 27 is arranged so as to overlap the upper part of the electrode group 4 so that the burr contacts the connection piece 50 of the positive electrode 6. And resistance welding is performed. At this time, the welding current concentrates on the burr part, and a part of the burr part melts and adheres to the connection piece 50 of the positive electrode 6.

  As described above, the electrode group 4 to which the positive electrode current collector 28 is attached is accommodated in the outer can 2. Since the outermost peripheral portion of the electrode group 4 is not covered with the separator 10 and is formed by a part of the negative electrode 8 (outermost peripheral portion), the negative electrode 8 is in contact with the inner peripheral wall 21 of the outer can 2. Yes. Thereby, the negative electrode 8 is electrically connected to the outer can 2 (negative electrode terminal) at the outermost peripheral portion.

  On the other hand, the tip of the positive electrode ribbon 26 extending from the connection plate 27 is resistance-welded to the lid plate 16 of the sealing body 14 and is electrically connected. Thereby, the positive electrode 6 and the positive electrode terminal 22 are electrically connected.

  In this manner, a predetermined amount of alkaline electrolyte is continuously injected into the outer can 2 containing the electrode group 4. Thereafter, the outer can 2 is sealed by the sealing body 14, whereby the battery 1 according to the present invention is obtained.

  As described above, the battery 1 according to the present invention thus obtained has the protruding edge 32 of the positive electrode 6 protruding from the upper end of the electrode group 4, and the protruding edge 32 and the positive electrode current collector. The connection plate 27 of the body 28 is resistance welded. Here, in the outermost peripheral range V of the protruding end edge portion 32, welding by point contact is performed at a portion where the upper end edge 33 intersects the burr in the slit 30 of the connection plate 27. A representative portion of the portion welded in this point contact state is indicated by reference symbol A in FIG. On the other hand, since the connection piece 50 is provided in the inner peripheral range W of the projecting end edge portion 32, welding is performed in a state where the upper surface of the connection piece 50 and the burr in the slit 30 of the connection plate 27 are in line contact. Yes. A representative portion of the portion welded in this line contact state is indicated by reference symbol B in FIG. Since the separator 10 is thin, it is difficult to see the separator 10 as well, so the illustration of the separator 10 is omitted.

  Conventionally, only welding by point contact between the upper end edge 33 of the projecting end edge portion 32 and the burr in the slit 30 of the connection plate 27 has been used. However, in the present invention, a large number of connection pieces 50 are provided in the inner circumferential range W, and the burrs of the connection pieces 50 and the slits 30 are welded in a line contact state, so that the joining range is wider than before. . For this reason, since the internal resistance of the battery 1 is lower than that of the conventional battery, the battery 1 of the present invention has a higher rate discharge characteristic than the conventional battery.

  The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the type of battery is not limited to a nickel-hydrogen secondary battery, and a nickel-cadmium secondary battery. Or a lithium ion secondary battery.

DESCRIPTION OF SYMBOLS 1 Nickel metal hydride secondary battery 2 Exterior can 4 Electrode group 6 Positive electrode 8 Negative electrode 10 Separator 14 Sealing body 18 Insulation packing 22 Positive electrode terminal 26 Positive electrode ribbon 27 Connection board 28 Positive electrode current collector 32 Projection edge part 50 Connection piece V Outermost peripheral range W Inner circumference range

Claims (4)

A cylindrical outer can with a bottom including a negative electrode terminal;
A sealing body that is electrically connected to the positive electrode terminal and seals the upper end opening of the outer can;
A positive electrode and a negative electrode are overlapped via a separator and wound in a spiral shape, and a cylindrical electrode group housed together with an alkaline electrolyte in the outer can,
A positive electrode current collector disposed between the sealing body and the electrode group and energizing the positive electrode terminal and the positive electrode;
The positive electrode current collector has a metal connection plate,
The electrode group has a protruding edge portion in which an edge portion of the positive electrode facing the connection plate protrudes toward the connection plate,
The protruding end edge portion includes a bent piece that is bent toward a radially outer side of the electrode group at a tip thereof, and the alkaline secondary battery in which the bent piece and the connection plate are joined.   The alkaline secondary battery according to claim 1, wherein four or more bent pieces are provided per circumference of the wound positive electrode.   3. The alkaline secondary battery according to claim 1, wherein the bent piece is positioned at a portion of the protruding edge portion excluding the outermost peripheral portion of the positive electrode.   The length of the bent piece extending outward in the radial direction of the electrode group is S, the thickness of the positive electrode is t1, the thickness of the separator is t2, the thickness of the negative electrode is t3, and these t1, t2 The alkaline secondary battery according to any one of claims 1 to 3, which satisfies a relationship of S <T, where T is a total thickness of t3 and t3.

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