阅读说明：本技术 二次电池 (Secondary battery ) 是由 福田祐辅 柴冈浩行 麦间勲 横泽友美 于 2019-06-10 设计创作，主要内容包括：本发明的二次电池(102)具备外装罐(2)、和密闭外装罐(2)的开口(3)的封口体(14),和与电解液一起被收纳于外装罐(2)的内部的电极组(104),和设于电极组(104)和封口体(14)之间的、具有设于面向电极组(104)的电极组贯通孔(9)的位置的集电体中央贯通孔(29)的正极集电体(28)；封口体(14)包括在中央具有排气孔(19)的盖板(16),和设于从盖板(16)的外侧堵塞排气孔(19)的位置的阀体(20),和与盖板(16)电连接、并以将阀体(20)向着盖板(16)按压的状态收纳于内部的正极端子(22)；正极集电体(28)的集电体中央贯通孔(29)的内径尺寸DC在排气孔(19)的内径尺寸DL以下。(A secondary battery (102) of the present invention comprises an outer can (2), a sealing body (14) for sealing an opening (3) of the outer can (2), an electrode group (104) housed inside the outer can (2) together with an electrolyte, and a positive electrode collector (28) provided between the electrode group (104) and the sealing body (14) and having a collector center through hole (29) provided at a position facing an electrode group through hole (9) of the electrode group (104); the sealing body (14) comprises a cover plate (16) with an exhaust hole (19) in the center, a valve body (20) arranged at the position for blocking the exhaust hole (19) from the outer side of the cover plate (16), and a positive electrode terminal (22) which is electrically connected with the cover plate (16) and is accommodated in the interior of the cover plate (16) in a state that the valve body (20) is pressed towards the cover plate; the inner diameter DC of the collector central through hole (29) of the positive electrode collector (28) is less than or equal to the inner diameter DL of the exhaust hole (19).)

1. A secondary battery is provided with

A terminal doubling as an electrode, an outer can (2) having an opening (3), and

A sealing body (14) for sealing the opening (3) of the outer can (2), and

A secondary battery having an internal housing member housed together with an electrolyte in the exterior can (2),

The sealing body (14) comprises a cover plate (16) which is fitted into the opening (3) and has a vent hole (19) at the center, a valve body (20) which is provided at a position where the vent hole (19) is closed from the outside of the cover plate (16), and a lid member (22) which is electrically connected to the cover plate (16) and accommodates the valve body therein in a state where the terminal serving as the other electrode is pressed toward the cover plate,

The internal housing member includes a specific through hole having an inner diameter size equal to or smaller than an inner diameter size of the exhaust hole (19) at a position facing the exhaust hole (19).

2. The secondary battery according to claim 1,

The internal housing member includes an electrode group (4) which is formed by superposing the one electrode and the other electrode with a separator (10), is spirally wound, includes an electrode group through hole (9) penetrating the spirally wound center portion, and is cylindrical as a whole,

The specific through hole is the electrode group through hole (9).

3. The secondary battery according to claim 1,

The internal housing member includes an electrode group (104) which is formed into a cylindrical shape as a whole and includes an electrode group through hole (9) penetrating through a center portion of the spirally wound electrode group, the electrode group (104) being formed by laminating the one electrode and the other electrode with a separator (10), and a current collector (28) which is provided between the electrode group (104) and the sealing body (14) and has a current collector center through hole (29) provided at a position corresponding to the electrode group through hole of the electrode group,

The specific through-hole is at least one of the electrode group through-hole (9) and the current collector center through-hole (29).

4. The secondary battery according to claim 1,

the internal housing member includes an electrode group (104) which is formed into a cylindrical shape as a whole and includes an electrode group through hole (9) penetrating through a spirally wound center portion of the spirally wound electrode group, a current collector (28) which is provided on an upper portion of the electrode group (104) and has a current collector center through hole (29) provided at a position facing the electrode group through hole of the electrode group, and a current collecting lead (34) which is provided between the current collector (28) and the sealing member (14),

The current collecting reed (34) has a top wall (50) on the side of the sealing body, a bottom wall (36) on the side of the current collector opposite to the top wall (50), and a pair of side walls (42, 44) extending between the side edge of the top wall (50) and the side edge of the bottom wall (36) and facing each other,

The top wall (50) includes a top wall through hole (59) provided at a position facing the exhaust hole (19),

The bottom wall (36) includes a bottom wall through hole (51) provided at a position facing the current collector central through hole (29),

The specific through-hole is at least one of the electrode group through-hole (9), the current collector center through-hole (29), the top wall through-hole (59), and the bottom wall through-hole (51).

5. The secondary battery according to claim 3,

When the specific through hole is the current collector central through hole (29), the inner diameter of the exhaust hole (19) is DL, and the inner diameter of the current collector central through hole (29) is DC, the relation that DL is larger than or equal to DC is satisfied.

6. The secondary battery according to claim 4,

When the specific through hole is set as the current collector center through hole (29), the inner diameter of the exhaust hole (19) is set as DL, the inner diameter of the top wall through hole (59) is set as DT, the inner diameter of the bottom wall through hole (51) is set as DB, and the inner diameter of the current collector center through hole (29) is set as DC, the relation of DL ≧ DT ≧ DB ≧ DC is satisfied.

Technical Field

The present invention relates to a secondary battery, and more particularly to a secondary battery including a safety valve for discharging gas generated in the battery.

Background

In secondary batteries, various types of batteries have been developed in order to expand the applications. As one of such batteries, for example, a sealed alkaline secondary battery as shown below is known.

The sealed alkaline secondary battery includes a cylindrical outer can, an electrode group housed in the outer can together with an alkaline electrolyte, and a sealing member sealing an opening of the outer can. The sealing member includes a positive electrode terminal.

The following describes the steps of manufacturing the sealed alkaline secondary battery.

First, a positive electrode and a negative electrode are prepared. The positive electrode is formed by holding a positive electrode mixture containing a positive electrode active material, a positive electrode additive, a resin binder, and the like on a positive electrode base material. The negative electrode is formed by holding a negative electrode mixture containing a negative electrode active material, a negative electrode additive, a resin binder, and the like on a negative electrode base material. The prepared positive electrode and negative electrode are stacked with a resin separator interposed therebetween, wound around a winding core, and spirally wound (winding step). Then, the winding core is pulled out from the central portion of the spiral shape, and the portion from which the winding core is pulled out becomes a through hole. In this way, an electrode group having a through-hole (hereinafter, referred to as an electrode group through-hole) formed at the center thereof and having a substantially cylindrical shape as a whole can be obtained. The positive electrode of the electrode group is electrically connected to a strip-shaped collector bar made of a conductive material.

The electrode assembly obtained was housed in a bottomed cylindrical outer can. Next, an alkaline electrolyte is injected into the outer can. Here, in the injection step of injecting the alkaline electrolyte into the outer can, the alkaline electrolyte is injected through the electrode group through-hole. Thereby, the electrode group is impregnated with the alkaline electrolyte.

Then, the tip of the collector bar is welded to the sealing body. Therefore, the closure is caulked and fixed to the portion of the opening at the upper end of the outer container. Thus, a sealed alkaline secondary battery in which the opening of the outer can is sealed with the sealing member can be obtained.

However, in alkaline secondary batteries, a high-efficiency charge-discharge type capable of charging and discharging with higher efficiency is being developed. As the high-efficiency charge/discharge type battery, for example, a battery including a collector plate, a battery including a collector lead in addition to the collector plate, and the like are known.

First, a battery including a current collecting plate will be described.

In a battery including a current collector plate, in the production process of an electrode group, a positive electrode and a negative electrode are disposed in a state of being slightly offset from each other in the axial direction of the electrode group in a winding process, and a separator having a predetermined size is disposed at a predetermined position between the positive electrode and the negative electrode. In this state, the positive electrode, the separator, and the negative electrode are wound. As a result, the end edge of the positive electrode protrudes spirally from one end surface side of the electrode group, and the end edge of the negative electrode protrudes spirally from the other end surface side of the electrode group.

A positive electrode current collector formed of a metal plate material is welded to an end edge portion of the protruding positive electrode. On the other hand, a negative electrode current collector formed of a metal plate material is welded to the end edge of the protruding negative electrode. Thereby, the positive electrode and the positive electrode current collector are electrically connected in a wide range, and the negative electrode current collector are electrically connected in a wide range, so that the current collecting efficiency can be improved. As a result, it is possible to charge and discharge a battery including the current collector with high efficiency.

A battery including a current collecting lead other than the current collecting plate will be described. As such a battery including a current collector and a current collecting reed, for example, a battery as shown in japanese patent laid-open No. 2001-143684 is generally known.

The current collecting reed is a metal cylindrical body having a rectangular or elliptical cross-sectional shape, and is disposed between a current collector on the positive electrode side (hereinafter referred to as a positive electrode current collector) and the sealing member, and connects the sealing member and the positive electrode current collector. As a result, the positive electrode terminal of the sealing member is electrically connected to the positive electrode of the electrode group.

Here, the form of the current collecting lead is explained more specifically. In the current collecting reed, the peripheral wall portion is welded to the positive electrode current collector and the sealing member, respectively. Here, the peripheral wall of the tubular body has a portion welded to the positive electrode current collector as a bottom wall, a portion welded to the sealing member as a top wall, and a portion extending between the bottom wall and the top wall as a side wall. By making the distance between the bottom wall and the top wall as short as possible, that is, the length of the side wall in the direction along the axis of the battery as short as possible, the current-carrying path inside the battery can be shortened. The current collecting reed is formed of a metal plate material having a thickness larger than that of the current collecting bar. According to the above configuration, the internal resistance of the battery can be further reduced, and more efficient charge and discharge can be realized.

In the current collecting plate and the current collecting lead described above, in the step of injecting the alkaline electrolyte into the outer can, the through-holes are provided at positions coaxial with the axis of the electrode group through-hole so that the alkaline electrolyte is smoothly introduced into the electrode group through-hole of the electrode group. Here, the through hole provided in the positive electrode current collector is defined as a current collector center through hole, the through hole provided in the top wall of the current collecting lead is defined as a top wall through hole, and the through hole provided in the bottom wall of the current collecting lead is defined as a bottom wall through hole.

However, in the case of a sealed alkaline secondary battery, when the positive electrode and the negative electrode are erroneously charged (erroneous charging), overcharged, short-circuited from the outside, or put into fire by mistake, there is a possibility that gas in the battery is abnormally generated, the pressure in the battery is increased, and the outer can is deformed, and the battery is broken. Therefore, in order to prevent such rupture of the battery, the sealed alkaline secondary battery is provided with a safety valve that opens and releases the gas generated in the battery to the outside when the pressure of the gas exceeds a certain value.

Such a safety valve is usually provided in the sealing body. Here, the structure of the sealing body having the safety valve is, for example, as follows.

the sealing body is a cover plate having an exhaust hole, and is provided with a cover plate fitted to an opening of the outer can, a valve body disposed so as to close the exhaust hole, and a positive electrode terminal for housing the valve body.

The cover plate is a circular plate made of metal and fitted to the opening of the outer can. The exhaust hole is arranged in the central part of the cover plate.

The positive electrode terminal has, for example, a cylindrical peripheral wall, an opening located at one end of the peripheral wall, a flange provided on the periphery of the opening, and an end wall located at the other end opposite to the opening. The positive terminal has a flange portion welded to the lid plate in a state where the valve body is accommodated inside. Further, a deaeration hole is provided in the peripheral wall of the positive electrode terminal.

The valve body is formed of an elastic material, such as a rubber-like material, and has a cylindrical shape, for example. The valve body is accommodated in the positive electrode terminal, compressed between the end wall of the positive electrode terminal and the cover plate, and closed until reaching a predetermined pressure, thereby maintaining the sealing performance of the battery.

In the above valve body, if the gas in the battery is abnormally generated, the pressure of the gas in the battery rises, and exceeds a predetermined pressure, the valve body is elastically deformed by the pressure of the gas, and the vent hole of the lid plate is opened. Thus, the gas in the battery is discharged to the outside through the vent hole and the degassing hole of the positive electrode terminal, and the rupture of the battery is prevented. Then, as the pressure of the gas in the battery decreases, the valve body returns to its original shape, the vent hole of the lid plate closes, and the battery is sealed again.

In the current collecting reed described above, the top wall is welded to the cover plate of the sealing member. The top wall through hole provided in the top wall is located at a portion facing the gas discharge hole of the cover plate, and therefore, when the valve body opens the gas discharge hole of the cover plate, the flow of gas through the gas discharge hole is not obstructed.

However, when the sealed alkaline secondary battery is erroneously charged, overcharged, short-circuited from the outside, or accidentally ignited, the gas in the battery is abnormally generated and the battery is still hot. Here, if the temperature of the battery is high enough to melt the resin, the resin separator melts, and the resin components contained in the positive electrode mixture and the negative electrode mixture melt. If the resin is melted in this way, a melt of the resin is formed, and the melt may separate from the electrode group and become chips. Such fragments of the melt are likely to be generated mainly in the electrode group through-holes of the electrode group. When the internal pressure of the battery rises, the valve body deforms, and the safety valve opens, fragments of the melt generated in the through hole of the electrode group are sucked into the portion of the vent hole of the lid plate together with the discharged gas. That is, when the safety valve is opened, a flow of gas from the inside of the battery in a high pressure state to the outside of the battery in a low pressure state compared to the inside of the battery is generated, and along with this flow, fragments of the molten material in the electrode group through hole of the electrode group move in the electrode group through hole, fly out of the electrode group through hole, and are collected in the portion of the vent hole of the lid plate. As a result, the molten material fragments may block the exhaust holes of the cover plate. If the vent hole is closed, the safety valve is deactivated, and therefore, even if the internal pressure of the battery rises, the gas cannot be discharged to the outside. As a result, the battery may be broken.

Therefore, it is desired to develop a secondary battery with high safety that can reliably release gas to the outside without inhibiting the operation of a safety valve even when the battery is heated to a high temperature and the resin component inside melts to form a melt.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a secondary battery having higher safety than conventional ones.

In order to achieve the above object, according to the present invention, there is provided a secondary battery comprising a terminal serving as one electrode, an outer can having an opening, a sealing member for sealing the opening of the outer can, and an internal housing member housed in the outer can together with an electrolyte, wherein the sealing member comprises a lid plate fitted to the opening and having a gas discharge hole at the center, a valve body provided at a position for closing the gas discharge hole from the outside of the lid plate, and a lid member having a terminal serving as the other electrode electrically connected to the lid plate and housed therein in a state where the valve body is pressed toward the lid plate; the internal housing member includes a specific through hole having an inner diameter not larger than an inner diameter of the exhaust hole at a position facing the exhaust hole.

Preferably, the internal housing member includes an electrode group which is formed by laminating the one electrode and the other electrode with a separator, spirally wound, and has a cylindrical shape as a whole including an electrode group through hole penetrating through a center portion of the spirally wound electrode group, and the specific through hole is configured as the electrode group through hole.

Preferably, the internal housing member includes an electrode group which is formed by laminating the one electrode and the other electrode with a separator, is spirally wound, has a cylindrical shape as a whole and includes an electrode group through hole penetrating through a center portion of the spirally wound electrode group, and a current collector which is provided between the electrode group and the sealing body and has a current collector center through hole provided at a position corresponding to the electrode group through hole of the electrode group; the specific through-hole is at least one of the electrode group through-hole and the current collector center through-hole.

Preferably, the internal housing member includes an electrode group which is cylindrical as a whole and includes an electrode group through hole penetrating through a center portion of the spirally wound electrode group, a current collector which is provided on an upper portion of the electrode group and has a current collector central through hole provided at a position facing the electrode group through hole of the electrode group, and a current collecting tab which is provided between the current collector and the sealing member; the current collecting reed has a top wall located on the side of the sealing body, a bottom wall located on the side of the current collector and opposite to the top wall, and a pair of side walls extending between side edges of the top wall and the bottom wall and facing each other; the top wall includes a top wall through hole provided at a position facing the gas discharge hole, the bottom wall includes a bottom wall through hole provided at a position facing the current collector center through hole, and the specific through hole is at least one of the electrode group through hole, the current collector center through hole, the top wall through hole, and the bottom wall through hole.

Preferably, the specific through hole is the current collector center through hole, the inner diameter of the exhaust hole is DL, and the inner diameter of the current collector center through hole is DC, and the relationship of DL ≧ DC is satisfied.

Preferably, the specific through hole is the current collector center through hole, the inner diameter of the exhaust hole is DL, the inner diameter of the top wall through hole is DT, the inner diameter of the bottom wall through hole is DB, and the inner diameter of the current collector center through hole is DC, and the relationship of DL ≧ DT ≧ DB ≧ DC is satisfied.

A secondary battery according to the present invention is a secondary battery including a terminal serving as one electrode, an outer can having an opening, a sealing body for sealing the opening of the outer can, and an internal housing member housed in the outer can together with an electrolyte, wherein the sealing body includes a lid plate fitted to the opening and having a gas discharge hole at a center thereof, a valve body provided at a position for closing the gas discharge hole from an outside of the lid plate, and a lid member having a terminal serving as the other electrode electrically connected to the lid plate and housed in the interior of the lid plate in a state where the valve body is pressed toward the lid plate; the internal housing member includes a specific through hole having an inner diameter not larger than an inner diameter of the exhaust hole at a position facing the exhaust hole. In the secondary battery of the present invention, even when a melt is generated in a high-temperature state and fragments of the melt move from the specific through-holes of the internal housing member toward the vent holes of the lid plate, the fragments of the melt are prevented from spreading beyond the range of the vent holes because the specific through-holes are equal to or smaller than the vent holes, and the vent holes are not completely closed. As a result, the battery can be prevented from breaking by suppressing the inhibition of the operation of the safety valve. Therefore, if the present invention is applied, a secondary battery having higher safety than the conventional secondary battery can be obtained.

Drawings

fig. 1 is a partial sectional view showing a nickel-hydrogen secondary battery according to a first embodiment of the present invention.

Fig. 2 is a partial sectional view illustrating a nickel-hydrogen secondary battery according to a second embodiment of the present invention.

Fig. 3 is a plan view showing a positive electrode collector of a second embodiment of the present invention.

Fig. 4 is a partial sectional view showing a nickel-hydrogen secondary battery according to a third embodiment of the present invention.

Fig. 5 is a plan view showing a positive electrode collector of a third embodiment of the present invention.

Fig. 6 is a perspective view showing the current collecting reed in a state where the bottom wall side is on the upper side.

Fig. 7 is a perspective view showing the current collecting reed in a state where the top wall side is on.

Fig. 8 is a plan view showing an intermediate product of the current collecting reed.

Detailed Description

[ first embodiment ]

A cylindrical nickel-metal hydride secondary battery (hereinafter, referred to as a battery) 101 having an FA size will be described as an example of the secondary battery of the present invention with reference to the drawings.

The battery 101 includes an outer can 2 having a cylindrical shape with a bottom having an open upper end, the outer can 2 having conductivity, and a bottom wall thereof serving as a negative electrode terminal. The exterior can 2 contains a predetermined amount of an alkaline electrolyte (not shown) and an electrode group 4 constituting a part of the internal containing member.

As shown in fig. 1, the opening 3 of the outer can 2 is closed by a sealing member 14. The sealing body 14 includes a conductive disk-shaped cover plate 16, a valve element 20 disposed on the cover plate 16, and a positive electrode terminal (cover member) 22 similarly provided on the cover plate 16.

an annular insulating gasket 18 is disposed on the outer peripheral portion of the lid plate 16 so as to surround the lid plate 16, and the insulating gasket 18 and the lid plate 16 are fixed to the opening edge 17 of the outer can 2 by caulking the opening edge 17 of the outer can 2. That is, the lid plate 16 and the insulating gasket 18 cooperate with each other to seal the opening 3 of the outer can 2.

Here, the lid plate 16 has a vent hole 19 in the center. Then, a rubber valve body 20 is provided on the outer surface 16a of the cover 16 at a position to close the exhaust hole 19. The positive terminal 22 is electrically connected to the outer surface 16a of the cover 16 so as to cover the valve body 20.

The positive electrode terminal 22 has a cylindrical peripheral wall 24, an opening 25 located at one end of the peripheral wall 24, a flange 26 provided at the periphery of the opening 25, and an end wall 27 located at the other end opposite to the opening 25. The positive terminal 22 presses the valve body 20 against the cover 16. The positive electrode terminal 22 has a degassing hole 23 in a peripheral wall 24.

Normally, the exhaust hole 19 is hermetically closed by a valve body 20. If gas is generated inside the outer tank 2 and the pressure of the gas rises, the valve body 20 is compressed by the pressure of the gas, and the vent hole 19 is opened. As a result, the gas is discharged from the exterior can 2 to the outside through the gas discharge hole 19 and the degassing hole 23 of the positive electrode terminal 22. That is, the vent hole 19, the valve body 20, and the degassing hole 23 of the positive electrode terminal 22 form a safety valve for the battery 101.

The electrode group 4 includes a positive electrode 6, a negative electrode 8, and a separator 10 each having a strip shape, and is wound in a spiral shape with the separator 10 interposed between the positive electrode 6 and the negative electrode 8. That is, the positive electrode 6 and the negative electrode 8 are stacked on each other with the separator 10 interposed therebetween. The electrode group 4 is formed in a cylindrical shape as a whole. The outermost periphery of the electrode group 4 is formed by a part (outermost peripheral part) of the negative electrode 8, and is in contact with the inner peripheral wall of the outer can 2. That is, the negative electrode 8 and the outer can 2 are electrically connected to each other.

In the outer can 2, a bus bar 33 is disposed between a part of the electrode group 4 and the lid 16. Specifically, one end of the collector bar 33 is connected to the positive electrode 6, and the other end is connected to the cap plate 16. Therefore, the positive electrode terminal 22 and the positive electrode 6 are electrically connected to each other via the collector bar 33 and the lid plate 16.

The negative electrode 8 has a conductive negative electrode substrate formed in a belt shape, and a negative electrode mixture is held in the negative electrode substrate.

The negative electrode substrate is a band-shaped metal material, and a large number of through holes (not shown) penetrating in the thickness direction thereof are distributed. As such a negative electrode substrate, for example, a punched metal sheet can be used.

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

The negative electrode mix 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 as a negative electrode active material, and a hydrogen storage alloy generally used for a nickel-hydrogen secondary battery is suitably used. The binder described above serves to bind the particles of the hydrogen storage alloy and the conductive material to each other and also to bind the negative electrode mixture to the negative electrode substrate. Here, as the conductive material, a conductive material generally used for a nickel-hydrogen secondary battery is suitably used. The binder is not particularly limited as long as it is a binder generally used for a negative electrode of a nickel-hydrogen secondary battery, and for example, a resin-based material can be used. Specifically, a hydrophilic polymer, a hydrophobic polymer, a resin material such as carboxymethyl cellulose, or the like can be used.

The negative electrode 8 can be produced, for example, as follows.

First, a hydrogen absorbing alloy powder as an aggregate of hydrogen absorbing alloy particles, a conductive material, a binder and water are kneaded to prepare a negative electrode mixture paste. The obtained negative electrode mixture paste was applied to a negative electrode substrate and dried. After drying, the negative electrode substrate to which the negative electrode mixture containing the hydrogen storage alloy particles and the like is attached is rolled to increase the packing density of the hydrogen storage alloy, and then cut into a predetermined shape. Thereby, the negative electrode 8 can be obtained.

Next, the positive electrode 6 will be described.

The positive electrode 6 includes a conductive positive electrode base material and a positive electrode mixture held by the positive electrode base material. Specifically, the positive electrode base material has a porous structure having a large number of pores, and the positive electrode mixture is held in the pores and on the surface of the positive electrode base material.

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

The positive electrode mixture contains nickel hydroxide particles as positive electrode active material particles, a cobalt compound as a conductive material, a binder, and the like. The binder described above serves to bind the nickel hydroxide particles and the conductive material to each other and also to bind the nickel hydroxide particles and the conductive material to the positive electrode base material. Here, the binder is not particularly limited as long as it is a binder generally used for a positive electrode of a nickel-hydrogen secondary battery, and for example, a resin-based material can be used. Specifically, a resin material such as carboxymethyl cellulose, methyl cellulose, PTFE (polytetrafluoroethylene) dispersion, HPC (hydroxypropyl cellulose) dispersion, or the like can be used.

The positive electrode 6 can be produced, for example, as follows.

First, a positive electrode mixture slurry containing a positive electrode active material powder as an aggregate of positive electrode active material particles (nickel hydroxide particles), a conductive material, water, and a binder is prepared. The obtained positive electrode mixture slurry is filled in, for example, foamed nickel, and dried. After that, the foamed nickel filled with the nickel hydroxide particles or the like is subjected to roll pressing and cutting. This makes it possible to obtain the positive electrode 6 holding the positive electrode mixture. A collector bar 33 is welded to a predetermined position of the obtained positive electrode 6.

Next, as the separator 10, a strip body formed of a resin material, for example, a product obtained by applying a hydrophilic functional group to a nonwoven fabric made of polyamide fibers, or a strip body obtained by applying a hydrophilic functional group to a nonwoven fabric made of polyolefin fibers such as polyethylene or polypropylene, can be used.

The positive electrode 6 and the negative electrode 8 manufactured as described above are wound in a spiral shape with the separator 10 interposed therebetween. Thereby, the electrode group 4 is formed.

In the electrode group 4, the positive electrode 6, the negative electrode 8, and the separator 10 are wound around a winding core having a predetermined outer diameter, and after the winding operation, the winding core is pulled out, so that an electrode group through-hole 9 is formed in the center of the electrode group 4 so as to penetrate the center.

The obtained electrode group 4 was housed in the outer can 2. Next, a predetermined amount of alkaline electrolyte is injected into the outer can 2. The electrode group 4 is impregnated with the alkaline electrolyte solution, and a charge-discharge reaction between the positive electrode 6 and the negative electrode 8 proceeds. As the alkaline electrolyte, an alkaline electrolyte containing at least one of KOH, NaOH, and LiOH as a solute is preferably used.

Next, the other end of the current collecting bar 33 is welded to a predetermined position of the lid plate 16, and then the sealing body 14 is disposed in a state where the insulating gasket 18 is disposed on the outer periphery of the lid plate 16 at the upper end opening of the exterior can 2 housing the electrode group 4 and the alkaline electrolyte. After that, the opening 3 of the outer can 2 is sealed by caulking the opening edge 17 of the outer can 2. In this way, the battery 101 of the first embodiment sealed by the cap plate 16 having the positive electrode terminal 22 can be obtained.

As shown in fig. 1, in the battery 101 of the first embodiment, an electrode group 4 constituting a part of an internal housing member is housed in an outer can 2, and the electrode group 4 has an electrode group through-hole 9 as a specific through-hole at a position facing a gas discharge hole 19 of a sealing member 14. The inner Diameter (DG) of the electrode group through hole 9 is set to be equal to or smaller than the inner Diameter (DL) of the exhaust hole 19 (DL ≧ DG). That is, the electrode group through hole 9 has the same or smaller inner diameter size as the air vent hole 19.

In the battery 101 thus obtained, when the battery 101 is overcharged or the like, short-circuited from the outside, or accidentally ignited, gas is abnormally generated in the battery 101, and the battery 101 becomes hot. In this case, the resin component contained in the electrode group 4 may melt to generate a molten material of the resin component. The molten material is mainly generated in the electrode group through-hole 9 of the electrode group 4. In the battery in such a situation, the gas flow from the inside of the battery in a high-pressure state to the outside of the battery at a lower pressure than the inside of the battery is generated by the vent hole 19 opening in accordance with the operation of the safety valve. The fragments of the melt move in the electrode group through-holes 9 with the flow of the gas, fly out of the electrode group through-holes 9, and strike the exhaust holes 19 of the lid plate 16. In this case, fragments of the melt may adhere to the portion of the vent hole 19, block the vent hole 19, and disable the safety valve. However, in the battery 101 of the first embodiment described above, the electrode group through-hole 9, which is a specific through-hole, in the electrode group 4 constituting a part of the internal housing member has an inner diameter equal to or smaller than the inner diameter of the gas discharge hole 19, and therefore, the diffusion of fragments of the melt passing through the electrode group through-hole 9 in a range wider than the inner diameter of the electrode group through-hole 9 is suppressed. Therefore, the fragments of the melt are suppressed from covering the entirety of the exhaust hole 19. I.e. to prevent the vent hole 19 from being blocked by fragments of melt. As a result, the safety valve can be prevented from becoming inoperative, and the safety of the battery 101 can be improved.

As described above, the battery according to the first embodiment of the present invention can be said to be a secondary battery having higher safety than the conventional one.

[ second embodiment ]

The battery 102 of the second embodiment will be described with reference to fig. 2 and 3. In describing the battery 102 of the second embodiment, the same components as those of the battery 101 of the first embodiment as already described are denoted by the same reference numerals as those of the battery 101 of the first embodiment, and detailed description thereof will be omitted, and portions different from the battery 101 of the first embodiment will be described in detail.

In the electrode group 104 included in the battery 102, an end edge portion of the positive electrode 6 is exposed from one end surface in a spiral shape, and an end edge portion of the negative electrode 8 is exposed from the other end surface in a spiral shape. Here, the end edge of the exposed positive electrode 6 serves as a positive electrode connecting end edge portion 32, and the end edge of the exposed negative electrode 8 serves as a negative electrode connecting end edge portion (not shown). A positive electrode current collector 28 constituting a part of an internal housing member described later and a negative electrode current collector (not shown) constituting a part of the internal housing member are welded to the exposed positive electrode connecting end edge portion 32 and negative electrode connecting end edge portion, respectively.

The negative electrode 108 can be produced, for example, as follows.

First, a hydrogen absorbing alloy powder as an aggregate of hydrogen absorbing alloy particles, a conductive material, a binder and water are kneaded to prepare a negative electrode mixture paste. The obtained negative electrode mixture paste was applied to a negative electrode substrate and dried. After drying, the negative electrode substrate to which the negative electrode mixture including the hydrogen storage alloy particles and the like is attached is subjected to roll pressing and cutting. Thereby, an intermediate product of the negative electrode was obtained. The intermediate product of the negative electrode has a rectangular shape as a whole. Then, the negative electrode mixture is removed from a predetermined end edge portion of the intermediate product of the negative electrode, which is to be the negative electrode connecting end edge portion. Thus, the predetermined end edge portion becomes the negative electrode connecting end edge portion in the state where the negative electrode substrate is exposed. This results in a negative electrode 108 having a negative electrode connecting end edge portion. Here, the method of removing the negative electrode mixture is not particularly limited, and for example, the negative electrode mixture is preferably removed by applying ultrasonic vibration. The region other than the negative electrode connecting end edge portion holds the negative electrode mixture.

The positive electrode 106 can be manufactured, for example, as follows.

First, a positive electrode mixture slurry containing a positive electrode active material powder as an aggregate of positive electrode active material particles (nickel hydroxide particles), a conductive material, water, and a binder is prepared. The obtained positive electrode mixture slurry is filled in, for example, foamed nickel, and dried. After that, the foamed nickel filled with the nickel hydroxide particles or the like is subjected to roll pressing and cutting. Thus, an intermediate product of the positive electrode was obtained. The intermediate product of the positive electrode has a rectangular shape as a whole. Then, a predetermined end edge portion of the intermediate product of the positive electrode to be the positive electrode connecting end edge portion 32 is subjected to removal of the positive electrode mixture, so that the positive electrode base material is exposed. Next, the end edge portion from which the positive electrode mixture was removed was subjected to compression processing in the thickness direction of the intermediate product of the positive electrode to produce a positive electrode connection end edge portion 32. By performing the compression processing in this way, the positive electrode base material is in a dense state, and therefore the positive electrode connecting end edge portion 32 is in a state of being easily welded. In addition, the positive electrode connecting end edge portion 32 may be easily welded by joining a Ni-plated steel thin plate to the positive electrode connecting end edge portion 32. This results in positive electrode 106 having positive electrode connecting end edge portion 32. Here, the method for removing the positive electrode mixture is not particularly limited, and for example, a method of removing by applying ultrasonic vibration is suitably used. The region other than the positive electrode connecting end edge portion 32 is filled with the positive electrode mixture.

the positive electrode 106 and the negative electrode 108 manufactured as described above are wound in a spiral shape with the separator 10 interposed therebetween, thereby forming the electrode group 104. Specifically, during winding, the positive electrode 106 and the negative electrode 108 are disposed in a state slightly shifted from each other in the direction along the axial direction of the electrode group 104, and the separator 10 having a predetermined size is disposed at a predetermined position between the positive electrode 106 and the negative electrode 108, and the winding operation is performed in this state. As a result, the electrode group 104 having a cylindrical shape can be obtained. The resulting electrode set 104 is patterned as follows: on one end side of the electrode group 104, the positive electrode connecting end edge portion 32 of the positive electrode 106 protrudes from the negative electrode 108 adjacent to the positive electrode with the separator 10 interposed therebetween, and on the other end side of the electrode group 104, the negative electrode connecting end edge portion of the negative electrode 108 protrudes from the positive electrode 106 adjacent to the negative electrode with the separator 10 interposed therebetween.

The electrode group 104 is formed in a cylindrical shape having an electrode group through hole 9 as a whole. Then, in the electrode group 104, the positive electrode collector 28 is connected to the positive electrode connection end edge portion 32 forming one end portion of the cylindrical shape of the electrode group 104, and the negative electrode collector is connected to the negative electrode connection end edge portion forming the other end portion of the cylindrical shape of the electrode group 4.

The negative electrode current collector is not particularly limited, and a conventionally used metal plate having a disk shape is preferably used, for example. The prepared negative electrode current collector is welded to the negative electrode connecting end edge portion on the other end side of the electrode group 104.

Next, the positive electrode collector 28 will be described.

The positive electrode current collector 28 is a plate-like body formed of a conductive material, and the shape in plan view is not particularly limited, and any shape such as a circular plate shape or a polygonal shape can be adopted. The size of the positive electrode collector 28 is set to be smaller than the outer diameter of the electrode group 4 and to be able to cover the positive electrode connecting end edge portion 32 of the positive electrode 106 protruding from one end side of the electrode group 104.

In the present embodiment, as shown in fig. 3, a plate material having a decagonal shape in plan view is used. Specifically, the positive electrode current collector 28 is a decagonally-shaped Ni-plated steel sheet as a whole, and includes a circular current collector central through hole 29 located at the center, and 6 slits 30 radially extending so as to surround the current collector central through hole 29. The slits 30 are formed by punching, and preferably, projections (burrs) extending downward (toward the electrode group 104) are formed at the edge portions of the slits 30.

As shown in fig. 2, in the battery 102, a current collector tab 35 is interposed between the positive electrode current collector 28 and the sealing member 14, and the current collector tab 35 is electrically connected to the positive electrode current collector 28 connected to the positive electrode 106 of the electrode group 104 and the sealing member 14 having the positive electrode terminal 22.

The current collecting tab 35 used in the present embodiment is formed of a metal thin plate, and has one end connected to the lid plate 16 of the sealing member 14 and the other end connected to the positive electrode current collector 28.

Next, an example of the steps of assembling the battery 102 will be described.

First, the electrode group 104 as described above is prepared. Then, the negative electrode current collector is joined to the other end side of the electrode group 104, and then the electrode group 104 is housed in the outer can 2. Then, the negative electrode current collector is resistance welded to the bottom wall of the outer can 2.

Next, the positive electrode current collector 28 is placed on one end side of the electrode group 104, and the positive electrode connecting end edge portion 32 of the electrode group 104 and the positive electrode current collector 28 are resistance-welded. At this time, the current is concentrated on the portion where the burrs of the slit 30 of the positive electrode collector 28 and the positive electrode connecting end edge portion 32 contact each other, and a welded portion is formed at this portion, and the positive electrode connecting end edge portion 32 of the positive electrode 106 and the positive electrode collector 28 are welded to each other.

Next, the inner surface 16b of the lid plate 16 of the sealing body 14 is resistance-welded to one end of the current collecting tab 35, and then the other end of the current collecting tab 35 is resistance-welded to a predetermined position of the positive electrode current collector 28.

Next, after a predetermined amount of alkaline electrolyte is injected into outer can 2, sealing body 14 with insulating gasket 18 provided on the outer periphery of lid plate 16 is disposed at the upper end opening of outer can 2. After that, the opening 3 of the outer can 2 is sealed by caulking the opening edge 17 of the outer can 2. Thus, the battery 102 is formed.

As shown in fig. 2, in the battery 102 according to the second embodiment, a positive electrode current collector 28 constituting a part of an internal housing member is housed in the outer can 2, and the positive electrode current collector 28 has a current collector center through hole 29 as a specific through hole at a position facing the gas discharge hole 19 of the sealing member 14. Therefore, the inner Diameter (DC) of the current collector central through hole 29 is set to be equal to or smaller than the inner Diameter (DL) of the exhaust hole 19 (DL ≧ DC). That is, the collector central through hole 29 has the same or smaller inner diameter size as the gas discharge hole 19.

In the battery 102 according to the second embodiment, the size of the inner Diameter (DG) of the electrode group through hole 9 of the electrode group 104, which is not a specific through hole, is not particularly limited.

In the battery 102 thus obtained, when the battery 102 is overcharged or the like, short-circuited from the outside, or accidentally ignited, gas is abnormally generated in the battery 102, and the battery 102 becomes hot. In this case, the resin component contained in the electrode group 104 may be melted to generate a molten material of the resin component. The molten material is mainly generated in the electrode group through hole 9 of the electrode group 104. In the battery in such a situation, the gas flow from the inside of the battery in a high-pressure state to the outside of the battery at a lower pressure than the inside of the battery is generated by the vent hole 19 opening in accordance with the operation of the safety valve. The fragments of the melt move in the electrode group through-holes 9 with the flow of the gas, fly out of the electrode group through-holes 9, and strike the exhaust holes 19 of the lid plate 16. In this case, fragments of the melt may adhere to the portion of the vent hole 19, block the vent hole 19, and disable the safety valve. However, in the battery 102 of the second embodiment described above, the inner diameter of the collector center through hole 29, which is a specific through hole, in the positive electrode collector 28 constituting a part of the internal housing member is equal to or smaller than the inner diameter of the gas discharge hole 19, and therefore, the fragments of the melt passing through the collector center through hole 29 are suppressed from spreading over a wider range than the inner diameter of the collector center through hole 29. Therefore, the fragments of the melt are suppressed from covering the entirety of the exhaust hole 19. I.e. to prevent the vent hole 19 from being blocked by fragments of melt. As a result, the safety valve can be prevented from becoming inoperative, and the safety of the battery 102 can be improved.

as described above, the battery according to the second embodiment of the present invention can be said to be a secondary battery having higher safety than the conventional one.

In the battery 102 according to the second embodiment, the electrode group through-hole 9 of the electrode group 104 may not be a specific through-hole. In this case, the relationship between the inner Diameter (DL) of the exhaust hole 19, the inner Diameter (DC) of the current collector center through hole 29, and the inner Diameter (DG) of the electrode group through hole 9 is preferably such that DL is not less than DC.gtoreq.DG.

[ third embodiment ]

Battery 103 according to the third embodiment will be described with reference to fig. 4 to 8. In describing the battery 103 of the third embodiment, the same components as those of the battery 101 of the first embodiment and the battery 102 of the second embodiment already described are denoted by the same reference numerals as those of the battery 101 of the first embodiment and the battery 102 of the second embodiment, and detailed description thereof will be omitted, and portions different from the battery 101 of the first embodiment and the battery 102 of the second embodiment will be described in detail.

First, the positive electrode collector 128 will be explained.

The positive electrode collector 128 of the present embodiment is similar to the positive electrode collector 28 of the second embodiment, except that a protruding collector protrusion 31 is provided on the side opposite to the electrode group 104 side by press working at a predetermined position around the collector central through hole 29, as shown in fig. 5. The number of the current collector protrusions 31 is not particularly limited, and for example, 4 as shown in fig. 5 are preferably provided.

As shown in fig. 4, in battery 103, current collector 128 and sealing member 14 are electrically connected to positive electrode collector 128 connected to positive electrode 106 of electrode group 104 and sealing member 14 having positive electrode terminal 22 via current collector tab 34.

As is apparent from fig. 4, current collecting tab 34 used in the present embodiment has top wall 50 connected to lid plate 16 of sealing body 14, bottom wall 36 connected to positive electrode current collector 128, and a pair of side walls 42 and 44 respectively present between end edges 46 and 48 on both sides of top wall 50 and end edges 38 and 40 on both sides of bottom wall 36.

The current collecting lead 34 will be described with reference to fig. 6 and 7. Fig. 6 shows a state in which the bottom wall 36 is on the upper side and the top wall 50 is on the lower side, and fig. 7 shows a state in which the bottom wall 36 is on the lower side and the top wall 50 is on the upper side.

As is apparent from fig. 6, the bottom wall 36 is rectangular and has a circular bottom wall through hole 51 at the center. The bottom wall through-hole 51 is provided to prevent the alkaline electrolyte from accumulating on the bottom wall 36 and to smoothly diffuse the alkaline electrolyte into the electrode group 104. Here, the imaginary circle indicated by reference numeral 56 indicates a welding planned portion to be a welding portion in the case of performing resistance welding. In the present embodiment, the welding planned portion (bottom wall welding planned portion) 56 of the bottom wall 36 has 4 positions, and is located in the vicinity of 4 corner portions of the bottom wall 36 so as to surround the bottom wall through hole 51.

As can be seen in fig. 7, the top wall 50 is located opposite the bottom wall 36 and is generally rectangular in shape. Specifically, the top wall 50 is formed by 2 portions connected at the center in the short side direction thereof by a connecting portion 53 extending in the longitudinal direction. That is, the top wall 50 is formed by closely contacting one of the divided first half portions 52 and the other of the divided second half portions 54.

Specifically, the first half portion 52 and the second half portion 54 have opposing portions 52c, 54c opposing the bottom wall 36, and protruding portions 52a, 52b, 54a, 54b extending from the opposing portions 52c, 54c in the longitudinal direction of the top wall 50.

A semicircular first semicircular notch 55 facing the connection portion 53 is provided at the center of the facing portion 52c of the first half body 52. A semicircular second semicircular notch 57 facing the connection portion 53 is provided at the center of the facing portion 54c of the second half portion 54. The first semicircular notch 55 and the second semicircular notch 57 are located at positions opposite to each other, and form a circular top wall through hole 59 as a whole. When current collecting reed 34 is joined to sealing body 14, top wall through hole 59 faces exhaust hole 19 of lid plate 16.

The protruding portions 52a, 52b, 54a, and 54b are provided with spring projections 58 (see fig. 7) protruding toward the sealing member 14. The reed projection 58 is used as a portion for concentrating a welding current when resistance welding is performed. That is, in the resistance welding, the reed protrusion 58 is pressurized, and in this state, the reed protrusion 58 is melted by heat generated by a large current intensively flowing to the reed protrusion 58, and welding between the components is performed. The reed protrusion 58 serves as a welding-scheduled portion (top wall welding-scheduled portion) 68 on the top wall 50.

The spring projection 58 is formed by, for example, press working. Reference numeral 60 in fig. 6 denotes a concave portion formed on the back side of the reed protrusion 58 when the reed protrusion 58 is provided on the protruding portions 52a, 52b, 54a, and 54 b.

These projecting portions 52a, 52b, 54a, 54b extend outward from the opposing portions 52c, 54c opposing the bottom wall 36, and do not overlap the bottom wall 36. Therefore, when the current collecting lead 34 is resistance-welded to the sealing member 14, the electrode rods of the resistance welding machine can be brought into contact with the extending portions 52a, 52b, 54a, and 54b without interfering with the bottom wall 36. Further, the projecting portions 52a, 52b, 54a, and 54b project outward from the opposing portions 52c and 54c opposing the bottom wall 36, thereby improving the stability of the current collecting tabs 34 when the current collecting tabs 34 are joined to the sealing body 14.

As shown in FIG. 6, the side walls 42, 44 extend from the end edges 38, 40 on opposite sides of the bottom wall 36 to the end edges 46, 48 on opposite sides of the top wall 50. The shape of the side walls 42 and 44 in plan view is not particularly limited, and may be any shape such as a rectangle or a trapezoid.

The current collecting lead 34 can be manufactured as follows, for example.

First, an intermediate product 62 of the current collecting lead 34 formed of a thin plate having a substantially H-shaped plan view as shown in fig. 8 is prepared by processing a thin plate made of metal. The long portions of the intermediate product 62 on both sides are a first half body scheduled region 70 to be the first half body 52 and a second half body scheduled region 72 to be the second half body 54. The regions connected to the inside of the first half scheduled region 70 and the second half scheduled region 72 are scheduled side wall regions 74 and 76 to be the side walls 42 and 44. Then, a region sandwiched between the side wall scheduled region 74 and the side wall scheduled region 76 is a bottom wall scheduled region 78 which becomes the bottom wall 36.

The intermediate product 62 is provided with the spring tab portions 58 at predetermined positions on both end portions of the first half body scheduled region 70 and the second half body scheduled region 72 by press working. The portions of the reed projections 58 are fused by resistance welding to form welded portions.

In the intermediate product 62, the first semicircular notch 55 and the 2 nd semicircular notch 57 are provided at the centers of the side edges of the first half body scheduled region 70 and the second half body scheduled region 72 by punching.

in the intermediate product 62, a circular bottom wall through hole 51 is provided at the center of the bottom wall planned region 78.

The periphery of the bottom wall through hole 51 of the bottom wall planned region 78 is in contact with the collector protrusion 31 of the positive electrode collector 128, and a planned bottom wall welding planned portion 56 where a welded portion is formed by resistance welding is assumed to be 4, the planned bottom wall welding planned portion 56 being indicated by an imaginary circle.

In the intermediate product 62 obtained by performing the press working and the die cutting working, the current collecting tabs 34 shown in fig. 6 and 7 are formed by bending portions of an imaginary bending line 80 imaginary between the first half portion scheduled region 70 and the side wall scheduled region 76, an imaginary bending line 82 imaginary between the side wall scheduled region 76 and the bottom wall scheduled region 78, an imaginary bending line 84 imaginary between the bottom wall scheduled region 78 and the side wall scheduled region 74, and an imaginary bending line 86 imaginary between the side wall scheduled region 74 and the second half portion scheduled region 72. Further, the predetermined sidewall regions 74 and 76 are preferably formed in a curved shape. The first half 52 and the second half 54 are closely attached and connected at their respective distal ends to form a top wall 50 including a top wall through hole 59.

Next, an example of the assembly process of the battery 103 will be described.

First, the electrode group 104 as described above is prepared. Then, the negative electrode current collector is joined to the other end side of the electrode group 104, and then the electrode group 104 is housed in the outer can 2. Then, the negative electrode current collector is resistance welded to the bottom wall of the outer can 2.

Next, the positive electrode collector 128 is placed on one end side of the electrode group 104, and the positive electrode connecting end edge portion 32 of the electrode group 104 and the positive electrode collector 128 are resistance-welded. At this time, the current is concentrated on the portion where the burrs of the slit 30 of the positive electrode collector 128 and the positive electrode connecting end edge portion 32 are in contact, and a welded portion is formed at this portion, and the positive electrode connecting end edge portion 32 of the positive electrode 6 and the positive electrode collector 128 are welded.

subsequently, a predetermined amount of alkaline electrolyte is injected into the outer can 2. The alkaline electrolyte injected into the exterior can 2 is held in the electrode group 104, and most of it is held in the separator 10. The alkaline electrolyte causes an electrochemical reaction (charge-discharge reaction) to proceed during charge and discharge between the positive electrode 6 and the negative electrode 8. As the alkaline electrolyte, an aqueous solution containing at least one of KOH, NaOH, and LiOH as a solute is preferably used.

On the other hand, in another step, inner surface 16b of lid plate 16 of sealing body 14 and top wall 50 of current collecting tab 34 are resistance-welded to form a composite of sealing body 14 and current collecting tab 34. Specifically, the current is concentrated on the portions of the first half portion 52 and the second half portion 54, which are the top walls 50 of the current collecting tabs 34, where the tab projecting portions 58 contact the inner surface 16b of the lid plate 16 of the sealing member 14, and the welded portions are formed at these portions, whereby a composite body in which the sealing member 14 and the current collecting tabs 34 are welded is obtained.

Next, the above-described composite is placed on the upper portion of the positive electrode current collector 28. At this time, the position of the composite is aligned with respect to the slits 30 of the positive electrode collector 28 so that the portions 56 to be welded on the bottom walls 36 of the current collecting tabs 34 are in contact with the collector protrusions 31 of the positive electrode collector 28. An insulating gasket 18 is disposed on the outer peripheral edge of the lid plate 16 of the sealing member 14, and the lid plate 16 is attached to the upper end opening of the outer can 2 with the insulating gasket 18 interposed therebetween.

Then, a current is applied between the positive electrode terminal 22 and the negative electrode terminal of the battery 103 while applying a pressure, and resistance welding (projection welding) is performed. At this time, the current is concentrated on the portion where the collector protrusion 31 of the positive electrode collector 128 contacts the bottom wall welding portion 56 on the bottom wall 36 of the collector reed 34, and a welded portion is formed at this portion, and the positive electrode collector 128 and the bottom wall 36 of the collector reed 34 are welded.

After completion of the welding as described above, the opening 3 of the outer can 2 is sealed by caulking the opening edge 17 of the outer can 2. Thus, the battery 103 is formed.

As shown in fig. 4, in the battery 103 of the third embodiment, the electrode group 104, the positive electrode collector 128, and the current collecting lead 34, which are components of the internal housing member, are housed in the outer can 2. In each of the electrode group 104, the positive electrode collector 128, and the current collecting lead 34, a through hole is provided at a position facing the gas discharge hole 19 of the sealing member 14. Specifically, the top wall through hole 59, the bottom wall through hole 51, the current collector center through hole 29, and the electrode group through hole 9. In the present embodiment, the current collector center through hole 29 among these through holes is a specific through hole. Therefore, the inner Diameter (DC) of the collector center through hole 29, which is a specific through hole, is set to be equal to or smaller than the inner Diameter (DL) of the exhaust hole 19 (DL ≧ DC). That is, the collector central through hole 29 has the same or smaller inner diameter size as the gas discharge hole 19.

The inner diameter of the top wall through hole 59, the bottom wall through hole 51, and the electrode group through hole 9 is not particularly limited except for the collector center through hole 29 which is a specific through hole. In the present embodiment, the inner diameter Dimension (DG) of the electrode group through hole 9, the inner diameter Dimension (DT) of the top wall through hole 59, and the inner diameter Dimension (DB) of the bottom wall through hole 51 are set to values larger than the inner diameter Dimension (DC) of the current collector center through hole 29.

In the battery 103 thus obtained, when overcharged or the like, when short-circuited from the outside, when the battery is exposed to fire by mistake or the like, gas is abnormally generated in the battery 103, and the battery 103 becomes high in temperature. In this case, the resin component contained in the electrode group 104 may be melted to generate a molten material of the resin component. The molten material is mainly generated in the electrode group through hole 9 of the electrode group 104. In the battery in such a situation, the gas flow from the inside of the battery in a high-pressure state to the outside of the battery at a lower pressure than the inside of the battery is generated by the vent hole 19 opening in accordance with the operation of the safety valve. The fragments of the melt move in the electrode group through-holes 9 with the flow of the gas, fly out of the electrode group through-holes 9, and strike the exhaust holes 19 of the lid plate 16. In this case, fragments of the melt may adhere to the portion of the vent hole 19, block the vent hole 19, and disable the safety valve. However, in the battery 103 of the third embodiment described above, the inner diameter of the collector central through hole 29, which is a specific through hole, in the positive electrode collector 128 constituting a part of the internal housing member is equal to or smaller than the inner diameter of the gas discharge hole 19, and therefore, the fragments of the melt passing through the collector central through hole 29 are suppressed from spreading over a wider range than the inner diameter of the collector central through hole 29. Therefore, the fragments of the melt are suppressed from covering the entirety of the exhaust hole 19. I.e. to prevent the vent hole 19 from being blocked by fragments of melt. As a result, the safety valve can be prevented from becoming inoperative, and the safety of battery 103 can be improved.

as described above, the battery according to the third embodiment of the present invention can be said to be a secondary battery having higher safety than the conventional one.

In the third embodiment of the present invention, at least one of the through holes of the constituent members included in the internal housing member is set as the specific through hole. Then, the inner diameter of the specific through hole is set to be equal to or smaller than the inner diameter of the exhaust hole 19. Even if a melt of the resin component is generated in the battery and fragments thereof fly out of the specific through-hole and toward the gas discharge hole 19, the fragments do not spread over a range equal to or larger than the inner diameter of the specific through-hole, and therefore, even if the fragments reach the gas discharge hole 19, the whole gas discharge hole 19 is not covered. Therefore, the operation of the safety valve is prevented from being hindered, and the battery is prevented from being broken.

In a preferred embodiment, when the inner diameter of the exhaust hole 19 is DL, the inner diameter of the top wall through hole 59 is DT, the inner diameter of the bottom wall through hole 51 is DB, and the inner diameter of the current collector center through hole 29 is DC, the relationship of DL ≧ DT ≧ DB ≧ DC is satisfied.

In the battery 103 according to the third embodiment, the electrode group through-hole 9 of the electrode group 104 may not be a specific through-hole. In this case, the relationship between the inner Diameter (DL) of the gas discharge hole 19, the inner Diameter (DT) of the top wall through hole 59, the inner Diameter (DB) of the bottom wall through hole 51, the inner Diameter (DC) of the collector center through hole 29, and the inner Diameter (DG) of the electrode group through hole 9 is preferably DL ≧ DT ≧ DB ≧ DC ≧ DG.

In recent years, various devices have been increasingly downsized, and efficient charging and discharging are also required for the small devices. Under such circumstances, a small-sized battery called FA-shaped, AA-shaped, or AAA-shaped used in small-sized devices is required to be able to be charged and discharged with higher efficiency.

Among these small batteries, it is necessary to further reduce the size of the components as compared with the case of a large battery called a D-shaped or C-shaped battery having an outer diameter of 19mm or more. With the miniaturization of the constituent members, the exhaust holes become more easily clogged with the melt. If the vent hole is clogged, rupture of the battery is more likely to occur due to malfunction of the safety valve.

In view of the above situation, in the present invention, even when a melt is generated and reaches the vent hole, the vent hole can be prevented from being completely covered, and the safety valve can be prevented from being inactivated, and therefore, the present invention is effective for suppressing rupture of a small battery having excellent charge and discharge characteristics at a high rate, specifically, a battery having a diameter of less than 19 mm.