Electrode for alkaline rechargeable battery and alkaline rechargeable battery

Abstract

The present invention provides an electrode for an alkaline rechargeable battery and an alkaline rechargeable battery that suppress the increase in internal pressure of the battery. The electrode for an alkaline rechargeable battery includes a strip-shaped core and an electrode mixture layer carried on the core. The electrode is opposite to a gas generating electrode via a separator, and is wound together with the gas generating electrode and the separator to form a spiral shape. The electrode has: a first circumference, which is the first circumference where the winding starts in the spiral shape and is only opposite to the gas generating electrode; a middle part, which is the middle part after the second circumference, and the inner surface and the outer surface are opposite to the gas generating electrode; and an outermost circumference, which is the outermost circumference, and only the inner surface is opposite to the gas generating electrode. The electrode mixture layer contains a substance that produces a reaction that consumes the gas generated at the end of the charge of the battery. The substance is contained most in the first circumference.

Description

Technical Field

[0001] The present invention relates to an electrode for an alkaline secondary battery and an alkaline secondary battery using the electrode. Background Art

[0002] As one of the alkaline rechargeable batteries, nickel-metal hydride rechargeable batteries are known. Compared with nickel-cadmium rechargeable batteries, nickel-metal hydride rechargeable batteries have higher capacity and better environmental safety. Therefore, nickel-metal hydride rechargeable batteries are used for various purposes such as various portable devices and hybrid electric vehicles. For nickel-metal hydride rechargeable batteries, various uses have been found on the one hand, and on the other hand, low cost is expected.

[0003] For example, as shown in Japanese Patent Gazette No. 2012-256522, it is proposed to thin the mixture layer at the winding start and winding end parts of the negative electrode containing a hydrogen storage alloy that are not opposite to the positive electrode, thereby achieving low cost of nickel-hydrogen rechargeable batteries while maintaining battery performance.

[0004] However, in a nickel-metal hydride secondary battery in which the material mixture layer at the winding start portion of the negative electrode that does not face the positive electrode is thinned, the internal pressure of the battery tends to increase.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an alkaline secondary battery electrode and an alkaline secondary battery which contribute to suppressing the increase in the internal pressure of the battery. Summary of the invention

[0006] According to one embodiment of the present invention, an electrode for an alkaline rechargeable battery is included in an electrode group stored in a container of an alkaline rechargeable battery, and is configured to include a strip-shaped core and an electrode mixture layer carried on the core. The alkaline rechargeable battery electrode is opposite to a gas generating electrode that generates gas at the end of charging of the alkaline rechargeable battery via a separator, and is wound together with the gas generating electrode and the separator to form a spiral shape, and has: a first circumference, which is the first circumference starting from the winding in the spiral shape, and only the outer surface is opposite to the gas generating electrode; a middle part, which is the middle part after the second winding in the spiral shape, and the inner surface and the outer surface are opposite to the gas generating electrode; and an outermost circumference, which is the outermost circumference of the winding in the spiral shape, and only the inner surface is opposite to the gas generating electrode. The electrode mixture layer contains a reactant, and the reactant generates a reaction that consumes the gas generated at the end of charging of the alkaline rechargeable battery. The first circumference contains more reactants than the middle part and the outermost circumference. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a perspective view showing a partially cutaway portion of an alkaline secondary battery according to an embodiment.

[0008] Figure 2 yes Figure 1 A transverse cross-sectional view of an alkaline rechargeable battery is shown.

[0009] Figure 3 It is shown for Figure 1 An expanded view of the negative electrode of an alkaline rechargeable battery is shown.

[0010] Figure 4 This is a table showing the relationship between the amount of the hydrogen storage alloy applied to the first peripheral portion of the negative electrode and the internal pressure of the battery.

[0011] Figure 5 It is a graph showing the relationship between the amount of the hydrogen storage alloy applied to the first peripheral portion of the negative electrode and the internal pressure of the battery. DETAILED DESCRIPTION

[0012] Next, a nickel-metal hydride rechargeable battery (hereinafter referred to as a battery) including an electrode according to an embodiment will be described in detail. The battery to which the present invention is applied is not particularly limited, and for example, Figure 1 2 AA size cylindrical batteries are shown.

[0013] like Figure 1 As shown, the battery 2 has a housing 10 in the shape of a bottomed cylinder with an open top. The bottom wall 35 of the housing 10 is conductive and functions as a negative terminal. A cover plate 14 in the shape of a conductive disk and a ring-shaped insulating seal 12 surrounding the cover plate 14 are arranged in the opening of the housing 10, and the opening edge of the housing 10 is riveted to fix the insulating seal 12 to the opening edge of the housing 10. That is, the cover plate 14 and the insulating seal 12 cooperate with each other to airtightly block the opening of the housing 10.

[0014] The cover plate 14 has an exhaust hole 16 in the center, and a rubber valve body 18 is arranged on the outer surface of the cover plate 14 to block the exhaust hole 16. In addition, a positive terminal 20 with a cylindrical shape with a flange is fixed to the outer surface of the cover plate 14 to cover the valve body 18, and the positive terminal 20 presses the valve body 18 against the cover plate 14. In addition, the positive terminal 20 is provided with a vent not shown. Therefore, the exhaust hole 16 is usually closed by the valve body 18 in an airtight manner.

[0015] On the other hand, if gas is generated in the housing 10 and the internal pressure thereof increases, the valve body 18 is compressed by the internal pressure to open the exhaust hole 16, and the gas is discharged from the housing 10 through the exhaust hole 16 and the vent hole of the positive terminal 20. That is, the exhaust hole 16, the valve body 18 and the positive terminal 20 form a safety valve for the battery.

[0016] The outer case 10 accommodates an electrode group 22. The electrode group 22 is composed of a strip-shaped positive electrode 24, a negative electrode 26, and a separator 28, and is wound in a spiral shape with the separator 28 interposed between the positive electrode 24 and the negative electrode 26. That is, the positive electrode 24 and the negative electrode 26 overlap each other via the separator 28.

[0017] In the outer case 10, the positive lead 30 is arranged between one end of the electrode group 22 and the cover plate 14, and each end of the positive lead 30 is connected to the positive electrode 24 and the cover plate 14, respectively. That is, the positive terminal 20 of the cover plate 14 and the positive electrode 24 are electrically connected to each other via the positive lead 30 and the cover plate 14. In addition, a circular insulating member 32 is arranged between the cover plate 14 and the electrode group 22, and the positive lead 30 extends through the cutout provided in the insulating member 32. A circular insulating member 34 is also arranged between the electrode group 22 and the bottom of the outer case 10.

[0018] A predetermined amount of alkaline electrolyte (not shown) is injected into the housing 10. The alkaline electrolyte is impregnated in the positive electrode 24, the negative electrode 26, and the separator 28, and a charge-discharge reaction is performed between the positive electrode 24 and the negative electrode 26. In addition, the type of the alkaline electrolyte is not particularly limited, but examples thereof include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, and aqueous solutions mixed with two or more of the above. In addition, the concentration of the alkaline electrolyte is not particularly limited, and for example, an 8N (predetermined degree) electrolyte can be used.

[0019] Reference Figure 2 In the electrode group 22 , the positive electrodes 24 and the negative electrodes 26 are alternately overlapped in the radial direction of the electrode group 22 with the separator 28 interposed therebetween.

[0020] Specifically, the electrode group 22 is formed by preparing a strip-shaped positive electrode 24, a negative electrode 26, and a separator 28, respectively, and winding these positive electrode 24 and negative electrode 26 into a spiral shape from one end side thereof using a winding core via the separator 28. Therefore, one end (winding start end) 36, 38 of the positive electrode 24 and the negative electrode 26 is positioned on the center side of the electrode group 22, and the other end (winding end end) 40, 42 of the positive electrode 24 and the negative electrode 26 is positioned on the outer peripheral side of the electrode group 22. In the first circumference (innermost circumference) 58 wound in a spiral shape at an angle of approximately 360° from the winding start end 36, only one surface of the negative electrode 26, that is, the outer peripheral surface side, faces the positive electrode 24 via the separator 28, and the other surface of the negative electrode 26, that is, the inner peripheral surface side, does not face the positive electrode 24.

[0021] On the other hand, the separator 28 is not wound around the outer periphery of the electrode group 22, and the outermost peripheral portion 50 of the negative electrode 26 forms the outer periphery of the electrode group 22. That is, the radially outer surface (outer surface) 52 of the electrode group in the outermost peripheral portion 50 of the negative electrode 26 is not covered by the separator 28 and is exposed, and the outer surface 52 is in contact with the peripheral wall of the outer shell, so that the negative electrode 26 and the outer shell 10 are electrically connected to each other. In addition, the radially inner surface (inner surface) 54 of the electrode group in the outermost peripheral portion 50 of the negative electrode 26 is opposite to the positive electrode 24 via the separator 28. That is, the outermost peripheral portion 50 of the negative electrode 26 is opposite to the positive electrode 24 only at the inner surface 54.

[0022] In the negative electrode 26, the middle portion 56 is continuous inside the outermost peripheral portion 50, and the first peripheral portion 58 is continuous near the winding center of the electrode group 22 further inside the middle portion 56. The middle portion 56 is a portion where both the outer surface 52 and the inner surface 54 of the negative electrode 26 face the positive electrode 24 via the separator 28, and is wound in a spiral shape and extends to the vicinity of the winding center of the electrode group 22. The first peripheral portion 58 is positioned at the center of the electrode group 22, and its outer surface 52 faces the positive electrode 24 via the separator 28.

[0023] Thus, the negative electrode 26 wound into a spiral shape is constructed to include: a first peripheral portion 58, of which only the outer surface 52 is opposite to the positive electrode 24 from the center of the winding; an intermediate portion 56, which is continuous with the first peripheral portion 58 and is located radially outside the first peripheral portion 58, and both the outer surface 52 and the inner surface 54 are opposite to the positive electrode 24; and an outermost peripheral portion 50, which is continuous with the intermediate portion 56 and is located radially outside the intermediate portion 56, and only the inner surface 54 is opposite to the positive electrode 24.

[0024] Furthermore, since the winding core is pulled out after winding, a space 44 corresponding to the shape of the winding core exists in the center portion of the electrode group 22 .

[0025] As the material of the separator 28, for example, a nonwoven fabric made of polyamide fibers or a nonwoven fabric made of polyolefin fibers such as polyethylene and polypropylene to which a hydrophilic functional group is imparted can be used.

[0026] The positive electrode 24 is composed of a conductive positive electrode substrate having a porous structure and a positive electrode mixture held in the pores of the positive electrode substrate. As the positive electrode substrate, for example, a nickel-plated mesh, sponge, or fiber-shaped metal body can be used.

[0027] The positive electrode mixture includes positive electrode active material particles, a conductive agent and a binder. The binder can play the following role: while bonding the positive electrode active material particles and the conductive agent to each other, the positive electrode mixture is bonded to the positive electrode substrate. The positive electrode active material particles are nickel hydroxide particles or high-order nickel hydroxide particles. In addition, the nickel hydroxide particles can form a solid solution containing cobalt, zinc, cadmium, etc. If the positive electrode mixture is maintained in the pores of the positive electrode substrate, a positive electrode mixture layer is formed.

[0028] As the conductive agent, one or more selected from cobalt compounds such as cobalt oxide (CoO), cobalt hydroxide (Co(OH)2) and cobalt (Co) can be used. The conductive agent is added to the positive electrode mixture as needed, and as a method of addition, in addition to the powder method, it can also be included in the positive electrode mixture in the coating method covering the surface of the positive electrode active material.

[0029] Negative electrode 26 Figure 3 As shown, there is a conductive negative electrode core 60 in a strip shape, and a negative electrode mixture 62 is carried on the negative electrode core 60. The negative electrode core 60 is composed of a sheet-shaped metal material with through holes distributed therein, for example, a stamped metal sheet or a sintered substrate formed by die-forming and sintering metal powder can be used. In addition, the negative electrode core 60 is an example of a core. If the negative electrode mixture is retained on the negative electrode core, a negative electrode mixture layer is formed. The negative electrode mixture layer is an example of an electrode mixture layer.

[0030] The negative electrode mixture 62 includes hydrogen storage alloy particles that can store and release hydrogen as negative electrode active materials, a conductive agent, and a binder. Here, as a binder, a hydrophilic or hydrophobic polymer can be used, and as a conductive agent, graphite, carbon black, Ketjen black, etc. can be used. The negative electrode mixture 62 is not only filled in the through hole of the negative electrode core 60, but also maintained in layers on both sides of the negative electrode core 60.

[0031] As the hydrogen storage alloy in the hydrogen storage alloy particles, a general hydrogen storage alloy is used without particular limitation.

[0032] [Example]

[0033] 1. Battery production

[0034] <Example 1>

[0035] (1) Preparation of positive electrode 24

[0036] Nickel hydroxide powder containing 2.5 mass % of zinc and 1.0 mass % of cobalt was added to a cobalt sulfate aqueous solution. While stirring the cobalt sulfate aqueous solution, a 1 mol / l sodium hydroxide aqueous solution was gradually added dropwise to react, and during the reaction, a precipitate was generated while maintaining the pH at 11. Then, the generated precipitate was filtered and washed with water, and then vacuum dried to obtain a nickel hydroxide powder whose surface was covered with 5 mass % of cobalt hydroxide.

[0037] The obtained nickel hydroxide powder covered with cobalt hydroxide was added to a 25% by mass sodium hydroxide aqueous solution. At this time, when the mass of the nickel hydroxide powder covered with cobalt hydroxide is set to P and the mass of the sodium hydroxide aqueous solution is set to Q, their mass ratio is P:Q=1:10. The sodium hydroxide aqueous solution to which the nickel hydroxide powder was added was heated for 8 hours while being stirred while maintaining the temperature at 85°C.

[0038] Thereafter, the nickel hydroxide powder after the heat treatment was washed with water and dried at 65° C., thereby obtaining a nickel positive electrode active material powder in which the surfaces of the nickel hydroxide particles were covered with high-order cobalt oxide.

[0039] 3 parts by mass of zinc oxide powder, 2 parts by mass of cobalt hydroxide powder, and 50 parts by mass of an aqueous solution containing 0.2% by mass of hydroxypropyl cellulose powder as a binder are added to 95 parts by mass of the obtained nickel positive electrode active material powder and kneaded to prepare a positive electrode mixture slurry. The active material slurry is filled into a nickel foam as a positive electrode substrate, dried, rolled, and cut to a specified size to obtain a nickel positive electrode plate.

[0040] (2) Preparation of negative electrode 26

[0041] Various metal materials of La, Sm, Mg, Ni and Al are mixed at a prescribed molar ratio and then charged into an induction melting furnace to be melted, and are cooled to produce an ingot.

[0042] The ingot was heat treated at 1000°C for 10 hours in an argon atmosphere to homogenize it, and then mechanically crushed in an argon atmosphere to obtain a rare earth-Mg-Ni hydrogen storage alloy powder. The particle size distribution of the obtained rare earth-Mg-Ni hydrogen storage alloy powder was measured using a laser diffraction / scattering particle size distribution measuring device (device name: SRA-150 manufactured by Microtrac). As a result, the average particle size corresponding to 50% of the mass-based integral was 35 μm.

[0043] The composition of the hydrogen storage alloy powder was analyzed by high frequency plasma spectrometry (ICP), and the composition was La 0.30 Sm 0.70 Mg0.10 Ni 3.30 Al 0.2 Furthermore, when the hydrogen storage alloy powder was subjected to X-ray diffraction measurement (XRD measurement), the crystal structure was Ce2Ni7 type.

[0044] 0.5 parts by mass of Ketjen black powder, 1.0 parts by mass of styrene butadiene rubber powder, 0.25 parts by mass of sodium polyacrylate powder, 0.05 parts by mass of carboxymethyl cellulose powder and 20 parts by mass of water were added to 100 parts by mass of the obtained hydrogen storage alloy powder and kneaded at 25°C to prepare a negative electrode mixture paste.

[0045] The negative electrode mixture paste was applied to both sides of the punched metal sheet as the negative electrode core to form a negative electrode mixture layer. The amount of mixture applied was set to 180 mg / cm2 in the first periphery 58. 2 , the middle part 56 is set to 174mg / cm 2 , the outermost part 50 is set to 105 mg / cm 2 The alloy conversion amount of the hydrogen storage alloy at this time is 177 mg / cm 2 , the middle part 56 is 171mg / cm 2 , the outermost part 50 is 103mg / cm 2 After the paste is dried, the negative electrode core body with the hydrogen storage alloy powder attached thereto is further roll-pressed to increase the amount of alloy per volume, and is cut to a specified size to produce a plate-shaped negative electrode mixture sheet.

[0046] (3) Assembly of NiMH rechargeable batteries

[0047] The positive electrode 24 and the negative electrode 26 produced by the above process are spirally wound relative to each other via a separator and housed in a casing 10, a specified amount of 8N electrolyte obtained by mixing KOH, NaOH, and LiOH in a weight ratio of 11:2.6:1.0 is added, and the opening of the casing 10 is blocked with a cover plate 14 to produce a cylindrical nickel-metal hydride rechargeable battery (battery A) with a nominal capacity of 1500mAh.

[0048] <Example 2>

[0049] The positive electrode 24 was prepared in the same manner as in Example 1. The amount of the negative electrode mixture applied was set to 193 mg / cm2 in the first peripheral portion 58. 2 , set the middle part 56 to 173 mg / cm 2 , the outermost portion 50 is set to 105 mg / cm 2 The negative electrode 26 is manufactured. The alloy conversion amount of the hydrogen storage alloy at this time is 189 mg / cm in the first peripheral portion 58. 2 , the middle part 56 is 170mg / cm2 , the outermost part 50 is 103mg / cm 2 A nickel-metal hydride rechargeable battery (battery B) similar to the battery of Example 1 was produced except that the amount of negative electrode mixture applied was different from that of Example 1.

[0050] <Example 3>

[0051] The positive electrode 24 was prepared in the same manner as in Example 1. The amount of the negative electrode mixture applied to the first peripheral portion 58 was set to 220 mg / cm 2 , set the middle part 56 to 169 mg / cm 2 , the outermost portion 50 is set to 105 mg / cm 2 The negative electrode 26 is manufactured. The alloy conversion amount of the hydrogen storage alloy at this time is 216 mg / cm in the first peripheral portion 58. 2 , the middle part 56 is 166mg / cm 2 , the outermost part 50 is 103mg / cm 2 A nickel-metal hydride rechargeable battery (battery C) similar to the battery of Example 1 was produced except that the amount of negative electrode mixture applied was different from that of Example 1.

[0052] <Comparative Example 1>

[0053] The positive electrode 24 was prepared in the same manner as in Example 1. The amount of the negative electrode mixture applied to the first peripheral portion 58 was set to 175 mg / cm 2 , set the middle part 56 to 175 mg / cm 2 , the outermost portion 50 is set to 105 mg / cm 2 The negative electrode 26 is manufactured. The alloy conversion amount of the hydrogen storage alloy at this time is 172 mg / cm in the first peripheral portion 58 and the middle portion 56. 2 , the outermost part 50 is 103mg / cm 2 A nickel-metal hydride rechargeable battery (battery D) similar to the battery of Example 1 was prepared except that the amount of the negative electrode mixture applied was different from that of Example 1.

[0054] <Comparative Example 2>

[0055] The positive electrode 24 was prepared in the same manner as in Example 1. The amount of the negative electrode mixture applied to the first peripheral portion 58 was set to 230 mg / cm 2 , set the middle part 56 to 168 mg / cm 2 , the outermost portion 50 is set to 105 mg / cm 2 The negative electrode 26 is manufactured. The alloy conversion amount of the hydrogen storage alloy at this time is 226 mg / cm in the first peripheral portion 58. 2 , the middle part 56 is 165mg / cm 2 , the outermost part 50 is 103mg / cm2 A nickel-metal hydride rechargeable battery (battery E) similar to the battery of Example 1 was produced except that the amount of negative electrode mixture applied was different from that of Example 1.

[0056] 2. Evaluation of NiMH rechargeable batteries

[0057] (1) Initial activation treatment

[0058] Batteries A to E were charged at a charging current of 0.4 A (0.1 C) for 16 hours and discharged at a discharging current of 0.8 A (0.2 C) to 1.0 V. This was repeated five times, with one cycle constituting one charge and discharge cycle, to perform initial activation treatment on each battery.

[0059] (2) Battery internal pressure characteristics

[0060] For Batteries A to E, a pressure sensor was attached to the bottom of the outer casing 10, and the batteries were charged at an ambient temperature of 25° C. with a charging current of 1.5 A for 90 minutes, and the internal pressure of each battery A to E was measured. Figure 4 The figure shows the relationship between the negative electrode mixture dosage, hydrogen storage alloy dosage, alloy dosage ratio of the first peripheral portion 58 and the outermost peripheral portion 50 relative to the middle portion 56, battery internal pressure and battery manufacturing yield rate of each battery's negative electrode 26. Figure 5 2 shows the relationship between the amount of hydrogen storage alloy in the first peripheral portion 58 and the internal pressure of the battery.

[0061] Depend on Figure 4 and Figure 5 It can be seen that the internal pressure of the battery is 0.69 MPa, 0.58 MPa, and 0.50 MPa in the batteries A, B, and C of Examples 1, 2, and 3, respectively, and 0.99 MPa in the battery D of Comparative Example 1. If the batteries A to C of Examples 1 to 3 are compared with the battery D of Comparative Example 1, it can be seen that the internal pressure of the battery is reduced by increasing the coating amount of the combined dosage of the first peripheral portion 58 of the spiral negative electrode 26. In the nickel-hydrogen rechargeable battery, oxygen is generated as gas from the positive electrode 24 at the end of charging, and the oxygen reacts with hydrogen on the surface of the negative electrode 26 to become water and is consumed. When the electrode group 22 is wound in a spiral shape and housed in the outer case 10, there is a space 44 with a hollow center. The gas generated inside the battery 2 accumulates in the space 44, so the gas consumption reaction is likely to occur at the first peripheral portion 58 of the negative electrode 26 close to the space 44. Therefore, by increasing the amount of hydrogen storage alloy in the first peripheral portion 58 of the negative electrode 26, the amount of hydrogen that reacts with oxygen can be increased, thereby increasing the reaction rate of the gas consumption reaction. As a result, it is considered that the amount of oxygen inside the outer casing 10 can be reduced to reduce the internal pressure of the battery.

[0062] On the other hand, the oxygen near the outermost portion 50 of the negative electrode 26 is less than the oxygen accumulated in the space 44. Therefore, even if the amount of alloy coated per unit area of ​​the outermost portion 50 is less than that of the middle portion 56, the impact on the increase in the internal pressure of the battery is small.

[0063] Specifically, in Battery A of Example 1, the amount of alloy in the first peripheral portion 58 increased by 3%, and the battery internal pressure decreased by about 30% compared to Battery D of Comparative Example 1. According to the measured values ​​of Battery B of Example 2 and Battery C of Example 3, it can be seen that if the amount of hydrogen storage alloy in the first peripheral portion 58 is further increased, the battery internal pressure gradually decreases.

[0064] However, it can be seen from the battery E of comparative example 2 that if the combined amount of the first peripheral portion 58 is increased to exceed the prescribed amount, the battery manufacturing yield rate decreases, although the battery internal pressure does not increase compared to the battery D of comparative example 1. This is because the size of the outer case 10 that accommodates the electrode group 22 is constant, and therefore, if the combined amount of the first peripheral portion 58 relative to the middle portion 56 exceeds 30 parts by mass, short circuit failures increase.

[0065] Thus, according to the present disclosure, by increasing the amount of the negative electrode mixture applied to the first peripheral portion 58 of the electrode 26 , it is possible to prevent the internal pressure of the battery from rising, and to manufacture a nickel-metal hydride secondary battery with higher safety.

[0066] According to the alkaline secondary battery electrode of the present disclosure, the reaction material in the first peripheral portion generates from the gas generating electrode and consumes the gas accumulated in the remaining space in the battery, thereby suppressing the increase in the internal pressure of the battery.

Claims

1. An electrode for an alkaline rechargeable battery, contained in an electrode group accommodated in a container of an alkaline rechargeable battery, characterized in that: The composition includes: a ribbon-shaped core; and an electrode mixture layer supported on the core, The electrode for the alkaline rechargeable battery is opposite to the gas generating electrode that generates gas at the end of charging of the alkaline rechargeable battery via a separator, and is wound together with the gas generating electrode and the separator to form a spiral shape, and has: a first peripheral portion, which is the first peripheral portion where the winding starts in the spiral shape, and only the outer surface is opposite to the gas generating electrode; a middle portion, which is the middle portion after the second circle of the winding in the spiral shape, and the inner surface and the outer surface are opposite to the gas generating electrode; and an outermost peripheral portion, which is the outermost peripheral portion of the winding in the spiral shape, and only the inner surface is opposite to the gas generating electrode, The electrode mixture layer contains a reaction material, which produces a reaction that consumes the gas generated at the end of charging of the alkaline rechargeable battery. The reactant is hydrogen, The electrode mixture layer comprises a hydrogen storage alloy capable of storing and releasing the hydrogen, The alloy amount ratio of the hydrogen storage alloy constituting the electrode mixture layer is higher in the first peripheral portion than in either the intermediate portion or the outermost peripheral portion.

2. The electrode for alkaline rechargeable battery according to claim 1, wherein The reactive substance is present most in the first peripheral portion, the reactive substance is less in the middle portion than in the first peripheral portion, and the reactive substance is less in the outermost peripheral portion than in the middle portion.

3. The electrode for alkaline rechargeable battery according to claim 1 or 2, characterized in that: The gas is oxygen.

4. The electrode for alkaline rechargeable battery according to claim 3, wherein The hydrogen storage alloy exists more in the first peripheral portion than in the middle portion and the outermost peripheral portion.

5. The electrode for alkaline rechargeable battery according to claim 4, characterized in that The hydrogen storage alloy is present most in the first peripheral portion, the hydrogen storage alloy is less in the middle portion than in the first peripheral portion, and the hydrogen storage alloy is less in the outermost peripheral portion than in the middle portion.

6. The electrode for alkaline rechargeable battery according to claim 1, wherein When the alloy ratio of the hydrogen storage alloy in the middle portion is assumed to be 100%, the alloy ratio of the hydrogen storage alloy in the first peripheral portion does not exceed 130%.

7. An alkaline rechargeable battery, characterized in that: include: container; as well as an electrode group housed in the container together with an alkaline electrolyte, The electrode group is wound in a spiral shape in a state where the positive electrode and the negative electrode overlap with each other via a separator. The positive electrode is the gas generating electrode according to claim 1, The negative electrode is the electrode for an alkaline secondary battery according to claim 1 or 2.

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