Alkaline storage batteries and battery packs

Abstract

This prevents objects placed near the battery from being contaminated by the electrolyte. [Solution] The alkaline storage battery 1 comprises an outer casing 2, a positive electrode plate 25 and a negative electrode plate 26 arranged in an inner space 8 formed inside the outer casing 2, an alkaline electrolyte in which the positive electrode plate 25 and the negative electrode plate 26 are immersed, a cover plate 11 that closes an opening 7 connecting the inner space 8 of the outer casing to the outside of the outer casing 2, a positive electrode cap 14 that electrically contacts the positive electrode plate 25, and a valve body 15. The positive electrode cap 14 comprises a cylindrical portion 16 along the side of a cylinder and a positive electrode terminal portion 17 along one bottom surface of the cylinder. The cover plate 11 has a through hole 21 that connects the positive electrode terminal inner space 19, surrounded by the cover plate 11, the cylindrical portion 16, and the positive electrode terminal portion 17, to the inner space 8 of the outer casing. The valve body 15 closes the through hole 21 when the pressure in the inner space 8 of the outer casing is less than a threshold, and opens the through hole 21 when the pressure in the inner space 8 of the outer casing is greater than a threshold.

Description

Technical Field

[0001] The technology of the present disclosure relates to alkaline storage batteries and battery packs.

Background Art

[0002] There are known alkaline storage batteries that release gas or electrolyte from inside the battery when the pressure inside the battery becomes high due to misuse such as overcharging or short - circuiting (Patent Documents 1 to 6). Such alkaline storage batteries can prevent the sealing body from coming off the outer can due to an increase in the pressure inside the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the electrolyte released from the alkaline storage battery scatters outside the alkaline storage battery, and such an alkaline storage battery has a problem that it may contaminate an object in the vicinity of the alkaline storage battery with the electrolyte.

[0005] The disclosed technology has been made in view of the above, and aims to provide an alkaline storage battery and a battery pack that suppress contamination of objects placed near the battery with the electrolyte. [Means for solving the problem]

[0006] An alkaline storage battery according to one aspect of the present disclosure comprises an outer casing, a positive electrode and a negative electrode disposed in an internal space formed inside the outer casing, an electrolyte in which the positive electrode and the negative electrode are immersed, a cover plate that closes an opening connecting the internal space of the outer casing to the outside of the outer casing, a positive electrode cap that electrically contacts the positive electrode, and a valve body, wherein the positive electrode cap has a cylindrical portion along the side surface of a cylinder and a positive electrode terminal portion along one bottom surface of the cylinder, the cover plate has a through hole that connects the internal space of the positive electrode terminal, surrounded by the cover plate, the cylindrical portion and the positive electrode terminal portion, to the internal space of the outer casing, and the valve body closes the through hole when the pressure in the internal space of the outer casing is less than a threshold, When the pressure inside the outer can is greater than the threshold, the through-hole is opened. The side surface is divided into a first side portion and a second side portion by two straight lines. The bottom surface of one of the circles is divided into a first sector adjacent to the first side portion and a second sector adjacent to the second side portion. The central angle of the first sector is 45 degrees or more and 120 degrees or less. An exhaust hole is formed in the first cylindrical portion of the cylindrical portion that is aligned with the first side portion, allowing the internal space of the positive electrode terminal to communicate with the outside. The cylindrical portion is formed such that no hole is formed in the second cylindrical portion of the cylindrical portion that is aligned with the second side portion, allowing the internal space of the positive electrode terminal to communicate with the outside. [Effects of the Invention]

[0007] The disclosed alkaline storage batteries and battery packs can prevent objects placed near the batteries from being contaminated by the electrolyte. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is a partial cross-sectional view showing a partially cut alkaline battery of the embodiment. [Figure 2] Figure 2 is a perspective view showing the cover plate and the positive electrode cap. [Figure 3] Figure 3 is a plan view showing the positive electrode cap. [Figure 4] Figure 4 is a perspective view showing a battery pack of an embodiment. [Figure 5] Figure 5 is a schematic perspective view showing a battery pack of an embodiment. [Figure 6] Figure 6 is a schematic top view showing a battery pack. [Figure 7] Figure 7 is a top view showing the alkalinity test paper after alkaline electrolyte has been scattered from the battery sample. [Modes for carrying out the invention]

[0009] The alkaline storage battery and battery pack according to the embodiments disclosed herein will be described below with reference to the drawings. However, the technology of this disclosure is not limited by the following description. Furthermore, the same reference numerals are used for the same components, and redundant explanations are omitted.

[0010] The alkaline battery 1 of this embodiment is a nickel-metal hydride secondary battery and comprises an outer casing 2 and a sealing body 3, as shown in Figure 1. Figure 1 is a partial cross-sectional view showing the alkaline battery 1 of this embodiment in a partially cutaway state. The outer casing 2 is formed from a conductive metal material. The outer casing 2 is formed in a bottomed cylindrical shape and comprises a side wall 5 and a bottom wall 6. The side wall 5 is formed in a generally cylindrical shape and is arranged along the side surface of the cylinder. The bottom wall 6 is formed in a generally disc shape and is arranged along one bottom surface of the cylinder. The bottom wall 6 is integrally formed with the side wall 5, with its edge connected to one end of the side wall 5. An opening 7 is formed in the part of the outer casing 2 corresponding to the other bottom surface of the cylinder. An internal space 8 is formed inside the outer casing 2. The internal space 8 is connected to the outside of the outer casing 2 through the opening 7.

[0011] The sealing body 3 comprises a cover plate 11, a gasket 12, a positive electrode cap 14, and a valve body 15. The cover plate 11 is made of a conductive metal material and is generally disc-shaped. The cover plate 11 is positioned along the bottom surface of the other end of the cylinder and closes the opening 7. The gasket 12 is made of an insulator and is generally annular-shaped. The gasket 12 is sandwiched between the edge of the cover plate 11 and the side wall 5 of the outer can 2 so that the cover plate 11 does not come into contact with the outer can 2.

[0012] The positive electrode cap 14 is formed from a conductive metallic material. The positive electrode cap 14 is formed in a flanged cylindrical shape and consists of a cylindrical portion 16, a positive electrode terminal portion 17, and a flange portion 18. The cylindrical portion 16 is generally cylindrical and positioned along the side of the cylinder. The positive electrode terminal portion 17 is generally disc-shaped and positioned along one bottom surface of the cylinder. The edge of the positive electrode terminal portion 17 is connected to one end of the cylindrical portion 16 and is integrally formed with the cylindrical portion 16. The flange portion 18 is disc-shaped with an opening in the center. The flange portion 18 is integrally formed with the cylindrical portion 16 such that the edge of the opening connects to the other end of the cylindrical portion 16. In other words, the positive electrode cap 14 is formed such that the flange portion 18 protrudes outward from the other end of the cylindrical portion 16.

[0013] The positive electrode cap 14 is positioned on the opposite side of the cover plate 11 from the side facing the internal space 8 of the outer can, such that the flange portion 18 contacts the cover plate 11. The positive electrode cap 14 is fixed to the cover plate 11 by welding the flange portion 18 to the cover plate 11. The sealing body 3 has a positive electrode terminal internal space 19 formed within it, surrounded by the cover plate 11, the cylindrical portion 16 of the positive electrode cap 14, and the positive electrode terminal portion 17. A through hole 21 is formed in the center of the cover plate 11, allowing the positive electrode terminal internal space 19 to communicate with the internal space 8 of the outer can.

[0014] The valve body 15 is made of rubber. The valve body 15 is disposed in the positive electrode terminal inner space 19. When the valve body 15 is disposed in the positive electrode terminal inner space 19, the valve body 15 is elastically deformed to seal the through hole 21.

[0015] The opening edge 22 around the end on the side of the opening 7 of the side wall 5 of the outer can 2 is caulked so that the inner diameter of the opening edge 22 is smaller than the inner diameter of the portion of the side wall 5 different from the opening 7. Due to the caulking of the opening edge 22 of the outer can 2, the gasket 12 is fixed to the outer can 2 so that the sealing body 3 does not come off from the outer can 2. Due to the caulking of the opening edge 22 of the outer can 2, the gasket 12 is deformed to seal the gap formed between the cover plate 11 and the outer can 2.

[0016] The alkaline storage battery 1 further includes an electrode group 24. The electrode group 24 includes a positive electrode plate 25, a negative electrode plate 26, and a separator 27. The positive electrode plate 25 includes a positive electrode base material and a positive electrode mixture. The positive electrode base material is formed of a porous material having conductivity, has flexibility, and is formed in a strip shape. Examples of the positive electrode base material include a nickel-plated net-like, sponge-like or fibrous metal, and foamed nickel (nickel foam). The positive electrode mixture contains a positive electrode active material, a conductive material, a positive electrode additive, and a binder. The positive electrode active material is formed of nickel hydroxide in which at least one of zinc, magnesium, and cobalt is dissolved. The conductive material is formed of a material having conductivity. Examples of the conductive material include a cobalt compound or cobalt. Examples of the cobalt compound include cobalt oxide and cobalt hydroxide. The binder joins the positive electrode active material, the conductive material, and the positive electrode additive, and joins the positive electrode active material to the positive electrode base material. Examples of the binder include carboxymethyl cellulose, methyl cellulose, polytetrafluoroethylene dispersion, and hydroxypropyl cellulose dispersion. The positive electrode mixture is held inside the pores of the positive electrode base material.

[0017] The negative electrode plate 26 includes a negative electrode substrate and a negative electrode mixture. The negative electrode substrate is formed of a conductive metal, has flexibility, and is formed in a strip shape. A large number of through holes are formed in the negative electrode substrate. Examples of the negative electrode substrate include punching metal and a sintered substrate obtained by sintering metal powder. The negative electrode mixture contains hydrogen storage alloy particles, a negative electrode additive, a conductive material, and a binder. The hydrogen storage alloy particles are formed of a hydrogen storage alloy capable of absorbing and releasing hydrogen. Examples of the hydrogen storage alloy include a rare earth-Mg-Ni-based hydrogen storage alloy containing rare earth elements, magnesium, and nickel. The conductive material is formed of a material having conductivity. Examples of the conductive material include carbon black and graphite. The binder joins the hydrogen storage alloy particles, the negative electrode additive, and the conductive material, and joins the hydrogen storage alloy particles to the negative electrode substrate. Examples of the binder include polymers having hydrophilicity or hydrophobicity. The negative electrode mixture is held by the negative electrode substrate.

[0018] The separator 27 is formed of a nonwoven fabric produced from insulator fibers and is formed of a flexible sheet. Examples of the insulator include polyamide or a polyolefin such as polyethylene or polypropylene to which a hydrophilic functional group is imparted.

[0019] The electrode group 24 is formed in a cylindrical shape by winding the positive electrode plate 25, the negative electrode plate 26, and the separator 27 with the separator 27 sandwiched between the positive electrode plate 25 and the negative electrode plate 26. The positive electrode plate 25 and the negative electrode plate 26 are not in direct contact with each other because the separator 27 is sandwiched between the positive electrode plate 25 and the negative electrode plate 26. The outer peripheral surface corresponding to the side surface of the cylinder of the electrode group 24 is covered with the negative electrode plate 26. The electrode group 24 is disposed in the outer can internal space 8 such that the negative electrode plate 26 contacts the side wall 5 of the outer can 2, that is, the negative electrode plate 26 is in electrical contact with the outer can 2.

[0020] The alkaline battery 1 further comprises a lower insulating member 31, an upper insulating member 32, and a positive electrode lead 33. The lower insulating member 31 is made of an insulator and is circular in shape. The lower insulating member 31 is positioned between the electrode group 24 in the internal space 8 of the outer casing and the bottom wall 6 of the outer casing 2 so that the positive electrode plate 25 does not come into contact with the bottom wall 6 of the outer casing 2. The upper insulating member 32 is made of an insulator and is circular in shape. The upper insulating member 32 is positioned between the electrode group 24 in the internal space 8 of the outer casing and the lid plate 11 so that the negative electrode plate 26 does not come into contact with the lid plate 11. A slit 34 is formed in the upper insulating member 32. The positive electrode lead 33 is made of a conductive material. The positive electrode lead 33 is positioned between the electrode group 24 in the internal space 8 of the outer casing and the lid plate 11 and passes through the slit 34. One end of the positive lead 33 is joined to the positive plate 25, and the other end of the positive lead 33 is joined to the cover plate 11. The positive cap 14 is electrically in contact with the positive plate 25 via the positive lead 33 and the cover plate 11.

[0021] The alkaline battery 1 further comprises an alkaline electrolyte (not shown). The alkaline electrolyte is formed from an aqueous sodium hydroxide solution containing sodium hydroxide (NaOH). The alkaline electrolyte is placed in the internal space 8 of the outer casing and permeates the electrode group 24 such that the positive electrode plate 25 and the negative electrode plate 26 are immersed in the alkaline electrolyte.

[0022] Figure 2 is a perspective view showing the cover plate 11 and the positive electrode cap 14. The side surface of the cylinder along which the cylindrical portion 16 follows includes a first straight line 41 and a second straight line 42. The first straight line 41 and the second straight line 42 are perpendicular to the bottom surface of the cylinder along which the cylindrical portion 16 follows. The side surface of the cylinder along which the cylindrical portion 16 follows is divided into a first side surface portion and a second side surface portion by the first straight line 41 and the second straight line 42. The cylindrical portion 16 is formed from a first cylindrical portion 43 and a second cylindrical portion 44. The first cylindrical portion 43 coincides with the portion of the cylindrical portion 16 along which the first side surface portion follows. The second cylindrical portion 44 coincides with the portion of the cylindrical portion 16 along which the second side surface portion follows.

[0023] The positive electrode cap 14 has a first exhaust hole 45 and a second exhaust hole 46. The first exhaust hole 45 is formed at the boundary between the cylindrical portion 16 and the flange portion 18; that is, a part of the first exhaust hole 45 is formed in the cylindrical portion 16, and the other part of the first exhaust hole 45 is formed in the flange portion 18. The first exhaust hole 45 is further formed in the region of the boundary between the cylindrical portion 16 and the flange portion 18 that intersects with a first straight line 41, and intersects with the first straight line 41. The positive electrode terminal internal space 19 is connected to the outside of the outer casing 2 via the first exhaust hole 45. The second exhaust hole 46 is formed at the boundary between the cylindrical portion 16 and the flange portion 18; that is, a part of the second exhaust hole 46 is formed in the cylindrical portion 16, and the other part of the second exhaust hole 46 is formed in the flange portion 18. The second exhaust port 46 is further formed in a region of the boundary between the cylindrical portion 16 and the flange portion 18 that intersects the second straight line 42, so as to separate the first exhaust port 45 and the second exhaust port 46. The positive terminal internal space 19 is further connected to the outside of the outer casing 2 via the second exhaust port 46.

[0024] The positive electrode cap 14 does not have any holes other than the first exhaust hole 45 and the second exhaust hole 46 that connect the positive electrode terminal internal space 19 to the outside of the outer casing 2. In other words, the cylindrical portion 16 is formed such that no holes connecting the positive electrode terminal internal space 19 to the outside of the outer casing 2 are formed in the second cylindrical portion 44.

[0025] Figure 3 is a plan view showing the positive electrode cap 14. The circle, which is one of the base surfaces along which the positive electrode terminal portion 17 of the cylinder is aligned, is formed from a first sector and a second sector. The first sector is adjacent to the first side surface along which the first cylindrical portion 43 is aligned; that is, the arc of the first sector coincides with a part of the first side surface. The second sector is adjacent to the second side surface along which the second cylindrical portion 44 is aligned; that is, the arc of the second sector coincides with a part of the second side surface. The central angle θ of the first sector is 45 degrees or more and 120 degrees or less. That is, the second cylindrical portion 44 is larger than the first cylindrical portion 43, and the area of ​​the second side surface is larger than the area of ​​the first side surface.

[0026] The battery pack 51 of the embodiment comprises a plurality of alkaline batteries 52 and an electronic component 53, as shown in Figure 4. Figure 4 is a perspective view showing the battery pack 51 of the embodiment. Each of the plurality of alkaline batteries 52 is formed in the same manner as the alkaline battery 1 described above. The plurality of alkaline batteries 52 are arranged side by side and fixed to each other. The electronic component 53 is located near the plurality of alkaline batteries 52 and is fixed to the plurality of alkaline batteries 52.

[0027] Figure 5 is a schematic perspective view showing a battery pack 51 of an embodiment. Multiple alkaline batteries 52 are connected in series or in parallel. Electronic components 53 include multiple terminals (not shown), a thermistor, and a protection circuit board. The multiple terminals are connected to the multiple alkaline batteries 52 and the thermistor and are used when the multiple alkaline batteries 52 and thermistor are connected to an external device. The thermistor 55 is in thermal contact with the multiple alkaline batteries 52 and is used when the temperature of the multiple alkaline batteries 52 is measured. The protection circuit board is provided in the middle of the circuit connecting the multiple alkaline batteries 52 and the multiple terminals. The protection circuit board measures the voltage of the multiple alkaline batteries 52 and, based on the measured voltage, interrupts the circuit between the multiple terminals and the multiple alkaline batteries 52 to prevent the multiple alkaline batteries 52 from being overcharged or over-discharged.

[0028] Each of the multiple alkaline storage batteries 52 is positioned such that the center 54 of the outer surface of the second cylindrical portion 44 of the positive electrode cap 14 faces the electronic component 53, as shown in Figure 6. Figure 6 is a schematic top view of the battery pack 51. That is, each of the multiple alkaline storage batteries 52 is positioned such that the electronic component 53 is not located in the area facing the outer surface of the first cylindrical portion 43 of the positive electrode cap 14.

[0029] The alkaline battery 1 is charged when a predetermined charging voltage is applied between the positive terminal portion 17 of the positive electrode cap 14 and the bottom wall 6 of the outer casing 2. The alkaline battery 1 may be overcharged if it is charged further after being charged to its full capacity. The alkaline battery 1 is discharged so that electricity flows to the load when the positive terminal portion 17 of the positive electrode cap 14 and the bottom wall 6 of the outer casing 2 are connected to a load.

[0030] Gas may be generated in the internal space 8 of the outer casing of the alkaline battery 1 when the alkaline battery 1 is overcharged or when the positive electrode terminal portion 17 of the positive electrode cap 14 and the bottom wall 6 of the outer casing 2 are electrically short-circuited. The pressure in the internal space 8 of the outer casing rises due to the generation of gas. The through hole 21 is opened when the pressure in the internal space 8 of the outer casing exceeds a predetermined pressure, as the valve body 15 elastically deforms. The gas and alkaline electrolyte contained in the internal space 8 of the outer casing are discharged from the internal space 8 of the outer casing through the through hole 21 to the internal space 19 of the positive electrode terminal when the through hole 21 is opened. The gas and alkaline electrolyte discharged into the internal space 19 of the positive electrode terminal are then discharged to the outside of the outer casing 2 through the first exhaust hole 45 and the second exhaust hole 46, and scatter into the area facing the first exhaust hole 45 and the second exhaust hole 46. The alkaline battery 1 can lower the pressure in the internal space 8 of the outer casing 2 by causing leakage, which releases gas and alkaline electrolyte to the outside of the outer casing 2. When the pressure in the internal space 8 of the outer casing rises, a force is applied to the sealing body 3 by the pressure in the internal space 8 of the outer casing 2, causing the sealing body 3 to detach from the outer casing 2. By lowering the pressure in the internal space 8 of the outer casing 1, the alkaline battery 1 can prevent rupture, which would occur if the sealing body 3 detached from the outer casing 2 due to the pressure in the internal space 8 of the outer casing 2.

[0031] In the alkaline storage battery 1, since no holes are formed in the second cylindrical portion 44 of the positive electrode cap 14, splashing of alkaline electrolyte into the area facing the center 54 of the outer surface of the second cylindrical portion 44 can be suppressed. Therefore, in the alkaline storage battery 1, when leakage occurs, objects placed in the area facing the center 54 of the outer surface of the second cylindrical portion 44 can be prevented from being contaminated by the alkaline electrolyte.

[0032] The battery pack 51 is configured such that the center 54 of the outer surface of the second cylindrical portion 44 of each positive electrode cap 14 of the multiple alkaline batteries 52 faces the electronic component 53. This prevents the electronic component 53 from being contaminated with alkaline electrolyte when leakage occurs in the multiple alkaline batteries 52. When the electronic component 53 is contaminated with alkaline electrolyte, it may be damaged and cease to function properly. The battery pack 51 prevents the electronic component 53 from being contaminated with alkaline electrolyte even when leakage occurs in any of the multiple alkaline batteries 52, thereby preventing the electronic component 53 from ceasing to function properly.

[0033] [Evaluation test of alkaline battery 1 of the embodiment] Multiple battery samples were prepared to confirm the effectiveness of the alkaline battery 1 of the embodiment. Table 1 shows the exhaust vent information for multiple battery samples. [Table 1] The multiple battery samples include the battery sample of Example 1, the battery sample of Example 2, the battery sample of Example 3, the battery sample of Example 4, the battery sample of Comparative Example 1, the battery sample of Comparative Example 2, the battery sample of Comparative Example 3, and the battery sample of Comparative Example 4.

[0034] Multiple battery samples are manufactured in the same manner as the alkaline storage battery 1 described above, except that the exhaust vent information is different from that of the multiple exhaust vent information. For example, multiple battery samples are manufactured so that the battery size is equal to that of the AA type and the rated capacity is 1000mAh, and are subjected to an activation treatment in which discharge and charge cycles are repeated several times.

[0035] Each of the multiple exhaust vent information entries indicates the "number of exhaust vents on the positive electrode cap" and the "arrangement angle of the exhaust vents on the positive electrode cap." The "number of exhaust vents on the positive electrode cap" indicated by the exhaust vent information entry corresponding to a particular battery sample among the multiple exhaust vent information entries indicates the number of exhaust vents formed on the positive electrode cap 14 of that battery sample. The "arrangement angle of the exhaust vents on the positive electrode cap" indicated by the exhaust vent information entry corresponding to a particular battery sample among the multiple exhaust vent information entries indicates the multiple positions in which the multiple exhaust vents formed on the positive electrode cap 14 of that battery sample are each positioned.

[0036] The positions of multiple parts of the cylindrical portion 16 of the positive electrode cap 14 correspond to multiple angles. For example, the position of the part of the cylindrical portion 16 along the first straight line 41 corresponds to 0 degrees, and the position of the part of the cylindrical portion 16 along the second straight line 42 corresponds to θ degrees. For example, when the "arrangement angle of the positive electrode cap's exhaust holes" indicated by the exhaust hole information for a certain battery sample includes "0°", that exhaust hole information indicates that a first exhaust hole 45 intersecting the first straight line 41 of the cylindrical portion 16 is formed in that battery sample. Furthermore, when the "arrangement angle of the positive electrode cap's exhaust holes" indicated by the exhaust hole information for a certain battery sample includes "X°", that exhaust hole information indicates that an exhaust hole is formed in the part of the cylindrical portion 16 corresponding to X degrees. In other words, when the "arrangement angle of the positive electrode cap's exhaust holes" indicated by the exhaust hole information for a certain battery sample shows "0°, X°", that battery sample is the same as the alkaline storage battery 1 described above, manufactured so that the central angle θ is equal to X degrees.

[0037] The exhaust port information corresponding to the battery sample of Example 1 indicates that the "number of exhaust ports on the positive electrode cap" is "2," and the "arrangement angle of the exhaust ports on the positive electrode cap" is "0°, 45°." In other words, the battery sample of Example 1 is the same as the alkaline storage battery 1 described above, manufactured so that the central angle θ is equal to 45 degrees. In this case, the center 54 of the second cylindrical portion 44 is formed in the portion of the cylindrical portion 16 corresponding to 202.5 degrees in the battery sample of Example 1.

[0038] The exhaust port information corresponding to the battery sample of Example 2 indicates that the "number of exhaust ports on the positive electrode cap" is "2," and the "arrangement angle of the exhaust ports on the positive electrode cap" is "0°, 60°." In other words, the battery sample of Example 2 is the same as the alkaline storage battery 1 described above, manufactured so that the central angle θ is equal to 60 degrees. In this case, the battery sample of Example 2 has the center 54 of the second cylindrical portion 44 formed in the portion of the cylindrical portion 16 corresponding to 210 degrees.

[0039] The exhaust port information corresponding to the battery sample of Example 3 indicates that the "number of exhaust ports on the positive electrode cap" is "2," and the "arrangement angle of the exhaust ports on the positive electrode cap" is "0°, 90°." In other words, the battery sample of Example 3 is the same as the alkaline storage battery 1 described above, manufactured so that the central angle θ is equal to 90 degrees. In this case, the battery sample of Example 3 has the center 54 of the second cylindrical portion 44 formed in the portion corresponding to 225 degrees of the cylindrical portion 16.

[0040] The exhaust port information corresponding to the battery sample of Example 4 indicates that the "number of exhaust ports on the positive electrode cap" is "2," and the "arrangement angle of the exhaust ports on the positive electrode cap" is "0°, 120°." In other words, the battery sample of Example 4 is the same as the alkaline storage battery 1 described above, manufactured so that the central angle θ is equal to 120 degrees. In this case, the battery sample of Example 4 has the center 54 of the second cylindrical portion 44 formed in the portion of the cylindrical portion 16 corresponding to 240 degrees.

[0041] The exhaust vent information corresponding to the battery sample in Comparative Example 1 indicates that the "number of exhaust vents on the positive electrode cap" is "4," and the "arrangement angle of the exhaust vents on the positive electrode cap" is "0°, 90°, 180°, 270°." In other words, the battery sample in Example 3 is the same as the alkaline storage battery 1 described above, in which four exhaust vents are formed in the cylindrical portion 16 of the positive electrode cap 14 at equal intervals in the circumferential direction.

[0042] The exhaust vent information corresponding to the battery sample in Comparative Example 2 indicates that the "number of exhaust vents on the positive electrode cap" is "3," and the "arrangement angle of the exhaust vents on the positive electrode cap" is "0°, 120°, 240°." In other words, the battery sample in Example 3 is the same as the alkaline storage battery 1 described above, in which three exhaust vents are formed in the cylindrical portion 16 of the positive electrode cap 14 at equal intervals in the circumferential direction.

[0043] The exhaust vent information for the battery sample in Comparative Example 3 indicates that the "number of exhaust vents on the positive electrode cap" is "2," and the "arrangement angle of the exhaust vents on the positive electrode cap" is "0°, 150°." In other words, the battery sample in Comparative Example 3 is the same as the alkaline storage battery 1 described above, which is manufactured so that the central angle θ is equal to 150 degrees. In this case, the battery sample in Comparative Example 3 has the center 54 of the second cylindrical portion 44 formed in the portion corresponding to 255 degrees of the cylindrical portion 16.

[0044] The exhaust vent information for the battery sample of Comparative Example 4 indicates that the "number of exhaust vents on the positive electrode cap" is "2," and the "arrangement angle of the exhaust vents on the positive electrode cap" is "0°, 180°." In other words, the battery sample of Comparative Example 4 is the same as the alkaline storage battery 1 described above, in which two exhaust vents are formed in the cylindrical portion 16 of the positive electrode cap 14 at equal intervals in the circumferential direction, and is the same as the alkaline storage battery 1 described above, which is manufactured so that the central angle θ is equal to 180 degrees. In this case, the battery sample of Comparative Example 4 has the center 54 of the second cylindrical portion 44 formed in the portion of the cylindrical portion 16 corresponding to 270 degrees.

[0045] Table 1 further shows multiple electrolyte leakage ranges corresponding to multiple battery samples. The electrolyte leakage range corresponding to a particular battery sample among the multiple electrolyte leakage ranges is derived by performing an electrolyte leakage verification test on that battery sample. In the electrolyte leakage verification test, an alkaline test paper is prepared, having a hole with a diameter equal to the outer diameter of the cylindrical portion 16 of the positive electrode cap 14. The alkaline test paper is attached to the battery sample so that the cylindrical portion 16 penetrates the hole and the alkaline test paper follows the flange portion 18. The battery sample is then overcharged to five times its rated capacity, i.e., overcharged to cause leakage, with the battery sample in an upright position so that the sealing body 3 is positioned on top of the outer casing 2.

[0046] As a result of leakage from the battery sample, the alkalinity test paper 61 forms a contaminated area 62 contaminated by the alkaline electrolyte scattered from the battery sample, and an uncontaminated area 63, as shown in Figure 7. Figure 7 is a top view showing the alkalinity test paper 61 after the alkaline electrolyte has scattered from the battery sample. The contaminated area 62 and the uncontaminated area 63 are formed such that, in the plane along which the alkalinity test paper 61 lies, the boundary between the contaminated area 62 and the uncontaminated area 63 follows a half-line that starts from the central axis 64 of the cylinder along which the cylindrical portion 16 of the positive electrode cap 14 lies and passes through the cylindrical portion 16.

[0047] The electrolyte leakage range indicates the range of the contaminated area 62 within the alkalinity test paper 61. In the plane along which the alkalinity test paper 61 lies, multiple half-lines passing through the cylindrical portion 16 of the positive electrode cap 14, starting from the central axis 64 of the cylinder along which the cylindrical portion 16 lies, correspond to multiple angles. The half-line passing through the first line 41 corresponds to 0 degrees, and the half-line passing through the second line 42 corresponds to θ degrees. For example, when the electrolyte leakage range indicates "0° to 300°", it indicates that the half-line 65 along which one side of the boundary between the contaminated area 62 and the uncontaminated area 63 lies corresponds to 0 degrees, and the half-line 66 along which the other side of the boundary between the contaminated area 62 and the uncontaminated area 63 lies corresponds to 300 degrees. Furthermore, when the electrolyte leakage range is "0° to 300°", the contamination area 62 is formed between the half-line 65 and the half-line 66 such that the contamination area 62 is located on the clockwise side of the half-line 65 with the central axis 64, and the contamination area 62 is located on the counterclockwise side of the half-line 66.

[0048] The electrolyte leakage range corresponds to the direction in which the alkaline electrolyte is scattered during leakage. In other words, when the electrolyte leakage range is "0° to 300°", it indicates that the alkaline electrolyte is scattered in the direction toward the central axis 64 in the region between the semicircle 65 and the semicircle 66.

[0049] The electrolyte leakage range corresponding to the battery sample in Example 1 is "-40° to 85°". In other words, the electrolyte leakage range corresponding to the battery sample in Example 1 indicates that when leakage occurs, the alkaline electrolyte is scattered in the direction of the region between the half-line corresponding to -40° and the half-line corresponding to 85°.

[0050] The electrolyte leakage range corresponding to the battery sample in Example 2 is "-40° to 100°". In other words, the electrolyte leakage range corresponding to the battery sample in Example 2 indicates that when leakage occurs, the alkaline electrolyte is scattered in the direction of the region between the half-line corresponding to -40° and the half-line corresponding to 100°.

[0051] The electrolyte leakage range corresponding to the battery sample in Example 3 is "-30° to 30°, 60° to 120°". In other words, the electrolyte leakage range corresponding to the battery sample in Example 3 indicates that when leakage occurs, the alkaline electrolyte will scatter in the direction of the region between the half-line corresponding to -30° and the half-line corresponding to 30°, and in the direction of the region between the half-line corresponding to 60° and the half-line corresponding to 120°.

[0052] The electrolyte leakage range corresponding to the battery sample in Example 4 is "-30° to 30°, 90° to 150°". In other words, the electrolyte leakage range corresponding to the battery sample in Example 4 indicates that when leakage occurs, the alkaline electrolyte will scatter in the direction between the half-line corresponding to -30° and the half-line corresponding to 30°, and in the direction between the half-line corresponding to 90° and the half-line corresponding to 150°.

[0053] The electrolyte leakage range corresponding to the battery sample of Comparative Example 1 is "-30° to 30°, 60° to 120°, 150° to 210°, and 240° to 300°". In other words, the electrolyte leakage range corresponding to the battery sample of Comparative Example 1 indicates that when leakage occurs in the battery sample of Comparative Example 1, the alkaline electrolyte will scatter in the following directions: towards the region between the half-line corresponding to -30° and the half-line corresponding to 30°, towards the region between the half-line corresponding to 60° and the half-line corresponding to 120°, towards the region between the half-line corresponding to 150° and the half-line corresponding to 210°, and towards the region between the half-line corresponding to 240° and the half-line corresponding to 300°.

[0054] The electrolyte leakage range corresponding to the battery sample of Comparative Example 2 is "-30° to 30°, 90° to 150°, and 210° to 270°". In other words, the electrolyte leakage range corresponding to the battery sample of Comparative Example 2 indicates that when leakage occurs in the battery sample of Comparative Example 2, the alkaline electrolyte will scatter in the direction of the region between the half-line corresponding to -30° and the half-line corresponding to 30°, the region between the half-line corresponding to 90° and the half-line corresponding to 150°, and the region between the half-line corresponding to 210° and the half-line corresponding to 270°.

[0055] The electrolyte leakage range corresponding to the battery sample of Comparative Example 3 is "-30° to 30°, 120° to 180°". In other words, the electrolyte leakage range corresponding to the battery sample of Comparative Example 3 indicates that when leakage occurs in the battery sample of Comparative Example 3, the alkaline electrolyte is scattered in the direction of the region between the half-line corresponding to -30° and the half-line corresponding to 30°, and in the direction of the region between the half-line corresponding to 120° and the half-line corresponding to 180°.

[0056] The electrolyte leakage range corresponding to the battery sample of Comparative Example 4 is "-30° to 30°, 150° to 210°". In other words, the electrolyte leakage range corresponding to the battery sample of Comparative Example 4 indicates that when leakage occurs in the battery sample of Comparative Example 4, the alkaline electrolyte is scattered in the direction of the region between the half-line corresponding to -30° and the half-line corresponding to 30°, and in the direction of the region between the half-line corresponding to 150° and the half-line corresponding to 210°.

[0057] The electrolyte leakage ranges corresponding to the battery samples of Examples 1 to 4 among the multiple electrolyte leakage ranges indicate that when the battery samples of Examples 1 to 4 leak, the alkaline electrolyte does not splash onto the area where the central 54 of the outer circumferential surface of the second cylindrical portion 44 of the positive electrode cap 14 faces. In other words, the multiple electrolyte leakage ranges indicate that the alkaline storage battery 1 described above can suppress the splashing of alkaline electrolyte onto the area where the central 54 of the outer circumferential surface of the second cylindrical portion 44 faces.

[0058] The multiple electrolyte leakage locations indicate that the area over which alkaline electrolyte is scattered in the battery samples of Examples 1 to 4 is narrower than the area over which alkaline electrolyte is scattered in the battery samples of Comparative Examples 1 and 2. In other words, the multiple electrolyte leakage locations indicate that the alkaline storage battery 1 described above has a smaller area contaminated with alkaline electrolyte when leakage occurs compared to the battery samples of Comparative Examples 1 and 2.

[0059] The electrolyte leakage area corresponding to the battery sample of Example 1 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 235 degrees. The electrolyte leakage area corresponding to the battery sample of Example 2 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 220 degrees. The electrolyte leakage area corresponding to the battery sample of Example 3 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 210 degrees. The electrolyte leakage area corresponding to the battery sample of Example 4 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 180 degrees. The electrolyte leakage area corresponding to the battery sample of Comparative Example 3 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 150 degrees. The electrolyte leakage area corresponding to the battery sample of Comparative Example 4 indicates that the central angle of the area including the region where the centers 54 of the outer circumferential surfaces of the second cylindrical portion 44 of the positive electrode cap 14 face each other, within a fan-shaped region different from the area where the alkaline electrolyte is scattered, is 120 degrees. In other words, the multiple electrolyte leakage areas indicate that, among the areas different from the area where the alkaline electrolyte is scattered, the central angle of the fan-shaped area including the area where the center 54 of the outer circumferential surface of the second cylindrical portion 44 of the positive electrode cap 14 faces each other is larger as the central angle θ decreases. To put it another way, the multiple electrolyte leakage areas indicate that the alkaline storage battery 1 described above can suppress contamination of objects placed in the area where the center 54 of the outer circumferential surface of the second cylindrical portion 44 of the positive electrode cap 14 faces each other with alkaline electrolyte when leakage occurs, to a smaller central angle θ.For example, the aforementioned alkaline battery 1 has shown that, when the magnitude of the central angle θ is 90 degrees or less, it can more effectively suppress contamination of objects placed in the region opposite the central 54 with alkaline electrolyte when leakage occurs, compared to alkaline batteries with a central angle θ greater than 90 degrees. Furthermore, the aforementioned alkaline battery 1 has shown that, when the magnitude of the central angle θ is 60 degrees or less, it can more effectively suppress contamination of objects placed in the region opposite the central 54 with alkaline electrolyte when leakage occurs, compared to alkaline batteries with a central angle θ greater than 60 degrees.

[0060] [Effects of the Alkaline Battery 1 of the Embodiment] The alkaline battery 1 of this embodiment comprises an outer casing 2, a positive electrode plate 25 and a negative electrode plate 26, an alkaline electrolyte, a cover plate 11, a positive electrode cap 14, and a valve body 15. The positive electrode plate 25 and the negative electrode plate 26 are arranged in an inner space 8 formed inside the outer casing 2. The positive electrode plate 25 and the negative electrode plate 26 are immersed in the alkaline electrolyte. The cover plate 11 closes an opening 7 that connects the inner space 8 to the outside of the outer casing 2. The positive electrode cap 14 is in electrical contact with the positive electrode plate 25. The positive electrode cap 14 comprises a cylindrical portion 16 along the side of the cylinder and a positive electrode terminal portion 17 along one bottom surface of the cylinder. The cover plate 11 has a through hole 21 that connects the positive electrode terminal inner space 19, surrounded by the cover plate 11, the cylindrical portion 16, and the positive electrode terminal portion 17, to the inner space 8 of the outer casing. The valve body 15 closes the through-hole 21 when the pressure in the internal space 8 of the outer can is less than a threshold, and opens the through-hole 21 when the pressure in the internal space 8 of the outer can is greater than the threshold.

[0061] The side surface is divided into a first side portion and a second side portion by a first straight line 41 and a second straight line 42. The circle surrounding one of the bottom surfaces is divided into a first sector adjacent to the first side portion and a second sector adjacent to the second side portion. The size of the central angle θ of the first sector is 45 degrees or more and 120 degrees or less. A first exhaust hole 45 is formed in the first cylindrical portion 43 along the first side portion of the cylindrical portion 16, which connects the positive electrode terminal internal space 19 to the outside. The cylindrical portion 16 is formed such that no hole connecting the positive electrode terminal internal space 19 to the outside is formed in the second cylindrical portion 44 along the second side portion of the cylindrical portion 16.

[0062] In this embodiment, when leakage occurs, the alkaline battery 1 can suppress the scattering of alkaline electrolyte into the area opposite to the central 54 of the outer circumferential surface of the second cylindrical portion 44. Therefore, in the embodiment, by positioning the central 54 of the outer circumferential surface of the second cylindrical portion 44 to face an object, the alkaline battery 1 can suppress contamination of the object with alkaline electrolyte when leakage occurs.

[0063] Furthermore, a second exhaust port 46 is formed at the end of the first cylindrical portion 43 of the alkaline battery 1 in the embodiment on the side of the second straight line 42. The first exhaust port 45 is formed at the end of the first cylindrical portion 43 on the side of the first straight line 41. Even in this case, the alkaline battery 1 in the embodiment is positioned so that the center 54 of the outer surface of the second cylindrical portion 44 faces the object, thereby suppressing contamination of the object with the alkaline electrolyte when leakage occurs. The alkaline battery 1 in the embodiment can further prevent rupture by allowing gas or alkaline electrolyte to be discharged through the other exhaust port even when one of the exhaust ports, the first exhaust port 45 or the second exhaust port 46, is clogged when leakage occurs.

[0064] The battery pack 51 of the embodiment comprises a plurality of alkaline batteries 52, including an alkaline battery 1, and an electronic component 53 fixed to the alkaline battery 1. The electronic component 53 is located on the side of the second cylindrical portion 44 of the alkaline battery 1. In this case, the battery pack 51 of the embodiment can suppress contamination of the electronic component 53 with alkaline electrolyte when leakage occurs in the alkaline battery 1.

[0065] Incidentally, the first exhaust port 45 and the second exhaust port 46 of the alkaline storage battery 1 described above are formed at the boundary between the cylindrical portion 16 and the flange portion 18, but they may also be formed so that a part of the exhaust port is not formed on the flange portion 18. Even in this case, when leakage occurs, the alkaline storage battery 1 can suppress contamination of an object placed in the area where the center 54 of the outer circumferential surface of the second cylindrical portion 44 faces the alkaline electrolyte.

[0066] Incidentally, the first cylindrical portion 43 of the positive electrode cap 14 of the alkaline storage battery 1 described above has two exhaust holes, a first exhaust hole 45 and a second exhaust hole 46, but the second exhaust hole 46 does not necessarily have to be formed. Even when the second exhaust hole 46 is not formed, the alkaline storage battery 1 can suppress contamination of an object placed in the area where the center 54 of the outer peripheral surface of the second cylindrical portion 44 faces each other with alkaline electrolyte when leakage occurs.

[0067] Incidentally, the first cylindrical portion 43 of the positive electrode cap 14 of the alkaline storage battery 1 described above has two exhaust holes, a first exhaust hole 45 and a second exhaust hole 46, but the first cylindrical portion 43 may have three or more exhaust holes. Even when the first cylindrical portion 43 has three or more exhaust holes, the alkaline storage battery 1 can suppress contamination of an object placed in the area facing the center 54 of the outer circumferential surface of the second cylindrical portion 44 with the alkaline electrolyte when leakage occurs. When the first cylindrical portion 43 of the alkaline storage battery 1 has three or more exhaust holes, it may become difficult to manufacture the positive electrode cap 14 or the durability of the positive electrode cap 14 may decrease. For this reason, the alkaline storage battery 1 described above can make it easier to manufacture the positive electrode cap 14 and improve the durability of the positive electrode cap 14 compared to other alkaline storage batteries in which the first cylindrical portion 43 has three or more exhaust holes.

[0068] Incidentally, although the alkaline battery 1 in the embodiment described above is formed from a nickel-metal hydride battery, it may also be formed from other aqueous alkaline batteries in which gas may be generated in the internal space 8 of the outer casing. Nickel-cadmium batteries are an example of such batteries. Even when the alkaline battery 1 is formed from such a secondary battery, it is possible to suppress contamination of objects placed near the battery with alkaline electrolyte when leakage occurs.

[0069] Incidentally, although the battery pack 51 described above has two alkaline batteries, it may also have three or more alkaline batteries. Even when the battery pack 51 has three or more alkaline batteries, it is possible to suppress contamination of the electronic components 53 with alkaline electrolyte.

[0070] Although examples have been described above, the examples are not limited to those described above. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the components described above can be combined as appropriate. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the gist of the examples. [Explanation of Symbols]

[0071] 1: Alkaline storage battery 2: Outer can 3: Sealing body 7: Opening 8: Internal space of the outer can 11: Lid plate 12: Gasket 14: Positive electrode cap 15: Valve body 16: Cylindrical section 17: Positive terminal part 19: Space inside the positive terminal 21: Through hole 25: Positive plate 26: Negative plate 41: 1st straight line 42:Second straight line 43: First cylindrical section 44: Second cylindrical section 45: First exhaust port 46: Second exhaust port 51: Battery pack 52: Multiple alkaline storage batteries 53: Electronic components

Claims

1. The outer can and A positive electrode and a negative electrode are arranged in the internal space of the outer can that is formed inside the outer can, An electrolyte in which the positive electrode and the negative electrode are immersed, A lid plate that closes the opening connecting the internal space of the outer can to the outside of the outer can, A positive electrode cap that electrically contacts the positive electrode, Equipped with a valve body, The aforementioned positive electrode cap is The cylindrical part along the side of the cylinder, It has a positive terminal portion along one of the bottom surfaces of the cylinder, The lid plate has a through hole formed therein that connects the positive terminal internal space, surrounded by the lid plate, the cylindrical portion, and the positive terminal portion, to the internal space of the outer can. The valve body closes the through-hole when the pressure in the internal space of the outer can is less than a threshold, and opens the through-hole when the pressure in the internal space of the outer can is greater than the threshold. The aforementioned side surface is divided into a first side surface portion and a second side surface portion by two straight lines. The circle which is one of the base surfaces is divided into a first sector adjacent to the first side surface and a second sector adjacent to the second side surface. The magnitude of the central angle of the first sector is 45 degrees or more and 120 degrees or less. An exhaust hole is formed in the first cylindrical portion of the cylindrical portion that runs along the first side portion, thereby connecting the internal space of the positive electrode terminal with the outside. The cylindrical portion is formed such that a hole connecting the internal space of the positive electrode terminal to the outside is not formed in the second cylindrical portion along the second side portion of the cylindrical portion. Alkaline storage battery.

2. An additional exhaust port is further formed at the end of one of the two straight lines of the first cylindrical portion. The exhaust port is formed at the end of the first cylindrical portion on the other side of the two straight lines. The alkaline storage battery according to claim 1.

3. The magnitude of the central angle of the first sector is 90 degrees or less. The alkaline storage battery according to claim 1.

4. The magnitude of the central angle of the first sector is 60 degrees or less. The alkaline storage battery according to claim 1.

5. The alkaline storage battery according to claim 1, Other alkaline storage batteries fixed to the aforementioned alkaline storage battery, The alkaline battery comprises an electronic component fixed to it, The electronic component is positioned on the side of the second cylindrical portion of the alkaline battery. Battery pack.

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