JP2004362956A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery equipped with a current breaking mechanism suitable for constructing the secondary battery with high capacity and a high output. <P>SOLUTION: The secondary cell is constructed by housing an electrode group 3 formed by winding a positive electrode plate and negative electrode plate through a separator, and jointing a positive electrode current collector plate 14 at one end, and jointing a negative electrode current collector plate 5 at the other end, in an external case 2 formed into a bottomed cylinder shape with a spacer 4 arranged at the positive electrode current collector plate 14 side, and by welding a protrusion part 14a of the positive electrode current collector plate 14 to a bottom part 2b of the external case 2 at a welding point A, and by sealing the opening part of the external case 2 by a sealing member 20. When internal pressure of the battery is increased in accordance with temperature increase of the battery due to overcharge or the like, and swelling generated at the bottom part 2b becomes large, electric connection between the positive electrode current collector plate 14 and the external case 2 is broken by the breakage of the welding point A, and a current circuit is broken. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary battery having a structure suitable for forming a high-capacity, high-output battery of 5 A / h or more.
[0002]
[Prior art]
At present, a power supply device using a lead storage battery or a nickel-hydrogen storage battery has been put into practical use as a battery for an electric vehicle or a hybrid vehicle using both an internal combustion engine and an electric motor. There is a demand for higher capacity and higher output, and lithium-ion secondary batteries are expected to achieve this. However, since the lithium ion secondary battery uses a flammable non-aqueous electrolyte with a high energy density, it immediately shuts off the current circuit when an electrical fault such as overcharge or external short circuit occurs. It is necessary to provide a structure that performs In addition, when the battery temperature rises for some reason and the pressure inside the battery rises, it is necessary to provide a structure for releasing the abnormal internal pressure to the outside and shutting off the current circuit before reaching the limit pressure.
[0003]
FIG. 8 shows a configuration of releasing an abnormal internal pressure and interrupting a current in a lithium ion secondary battery according to the related art. The sealing plate 62 for closing an opening of a cylindrical outer case 61 accommodating a power generation element is abnormal. An internal pressure release structure and a current interruption structure are provided.
[0004]
The sealing plate 62 has a cap 68 serving as an electrode terminal, a ring-shaped PTC element 67, and a thin plate serving as an explosion-proof valve 66, which is superimposed on an inner gasket 69. The peripheral portion of the disk holder 64 is folded back and caulked together with the thin plate to be formed, so that it is integrally formed. The sealing plate 62 is swaged and fixed to the outer case 61 via the outer gasket 63 to seal the opening of the outer case 61. The explosion-proof valve 66 has an easily breakable portion 66a formed in a C-shape and is welded to the current cutoff valve 65 at a welding point A at a central portion bulging into the inside of the battery. Since the positive or negative lead drawn from the electrode group is joined to the disk holder 64, a current circuit is provided by the current cutoff valve 65 from the disk holder 64, the explosion-proof valve 66 from the welding point A, and the cap through the PTC element 67. The cap 68 serves as a positive or negative terminal.
[0005]
When the temperature of the secondary battery having the sealing plate 62 having the above-described structure rises to a high temperature state due to overcharging, external heating, or the like, the reaction between the positive and negative electrode active materials and the electrolytic solution and the vaporization of the electrolytic solution, Gases are generated due to decomposition or the like, and abnormal heat is accelerated due to heat generated by the gas. The pressure inside the outer case 61 is abnormally increased due to a further temperature rise. The pressure increase in the outer case 61 extends from the opening formed in the disc holder 64 to the current cutoff valve 65 and pushes the current cutoff valve 65 outward, so that the increased internal pressure also acts on the explosion-proof valve 66 welded thereto. I do. When the pushing pressure applied to the explosion-proof valve 66 exceeds a predetermined pressure, the bulging portion of the explosion-proof valve 66 is reversed, so that the welding with the current cutoff valve 65 at the welding point A is broken, and the explosion-proof valve 66 and the current cutoff valve 65 are disconnected. If the connection between the battery and the current circuit is cut off, the current circuit is cut off, and if the cause of the temperature rise is an electrical one such as overcharging, the cause factor is eliminated. When the cause of the temperature rise is not electrical or when the internal pressure further rises, the explosion-proof valve 66 breaks from the easily breakable portion 66a, so that the gas in the outer case 61 passes through the opening formed in the cap 68. Since the external case 61 is released to the outside, the outer case 61 is prevented from being broken.
[0006]
A number of proposals have been made for a secondary battery having the above-described current interrupting structure and explosion-proof structure provided on a sealing plate in addition to the one proposed by the present applicant (see Patent Document 1) (Patent Document 2). reference).
[0007]
[Patent Document 1]
JP-A-09-129195 (pages 2-3, FIG. 1)
[0008]
[Patent Document 2]
JP-A-08-315798 (pages 3 and 4, FIG. 1)
[0009]
[Problems to be solved by the invention]
The current interrupting structure provided in the sealing plate according to the above prior art is effective for application to a relatively small lithium ion secondary battery, but has a high capacity and a high output as the object of the present invention is. It is not suitable for application to secondary batteries. That is, the current path is the disk holder 64, the current cutoff valve 65, the explosion-proof valve 66, the PTC element 67, and the cap 68, and the contact resistance and the long current path therebetween are formed. There are problems that arise.
[0010]
In addition, applying such a structure of the sealing plate 62 to a high-capacity, high-output battery also has a problem of sealing, and since there are many components, there is a problem that the number of assembling steps is large and the cost is high.
[0011]
In addition, the cause of the battery falling into an abnormal state includes mechanical or thermal factors, in addition to the above-described electrical factors such as overcharge, and in a battery having a high energy density such as a lithium ion secondary battery, It is necessary to ensure the safety associated with them. In particular, this is an important issue when configuring a high-capacity, high-output battery. The electrical factor is the above-mentioned overcharge, external short-circuit, or internal short-circuit, and the thermal factor is a case where the battery is exposed to a high-temperature environment, and the battery temperature rises. Since the internal pressure of the battery rises even when the battery is not in the state, the current cutoff mechanism is activated when the internal pressure rises to the limit, and the use of the secondary battery whose function is reduced due to exposure to high temperature is stopped. Further, when the internal pressure further increases, the explosion-proof valve is activated, and the abnormal internal pressure is released to the outside to prevent the battery from exploding. The mechanical factor is damage to the secondary battery due to crushing or the like, and suppresses occurrence of a failure when external pressure is applied. This can be solved by increasing the strength of the outer case, but the weight of the battery increases. Therefore, it is necessary to make the structure hard to be crushed even by an external pressure and to prevent a trouble from being caused by a slight deformation.
[0012]
An object of the present invention is to provide a secondary battery provided with a current interrupting structure suitable for a high-capacity, high-output secondary battery, having a reliable current interrupting function with a simple structure.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a secondary battery according to the present invention is configured such that a positive electrode plate and a negative electrode plate are cylindrically wound via a separator to form an electrode group, and a positive electrode plate is provided at one end of the electrode group. Or one of the negative electrode plates is connected to one of the electrode plates, and a current collector plate having a projection formed at the center with a diameter substantially equal to the diameter of the electrode plate group is disposed, and the one current collector plate is provided at the other end of the electrode plate group. The other current collecting plate connected to one of the unconnected positive electrode plate and the negative electrode plate and provided with an electrode terminal at the center is disposed, and the one current collecting plate is formed with a central opening that penetrates the protrusion. The electrode group is accommodated in an outer case formed in a bottomed cylindrical shape by disposing spacers such that one current collector plate is located on the bottom side of the outer case, and the bottom portion of the outer case and one projecting portion of the one current collector plate Are welded to each other, and the electrode group is impregnated with the electrolytic solution. By parts exposed, characterized in that formed by sealing with a sealing member.
[0014]
According to the above configuration, when the internal pressure of the battery increases for some reason, the bottom of the outer case, which is most likely to be deformed by the increase of the internal pressure, bulges outward. Since the bottom of the outer case penetrates the central opening of the spacer and is welded to the protrusion of the current collector, the bulge of the bottom of the outer case is restrained by the one current collector via the spacer, but the welding strength When the bulge exceeds the threshold value, the welding between the projection of the current collector and the outer case is broken. Since the outer case is connected to the one current collector plate by welding to form one electrode of the battery, the connection is cut off by the breakage of the welded portion, so that the current circuit of the secondary battery is cut off. Therefore, the current circuit is interrupted when the pressure in the outer case rises abnormally due to an electrical cause such as overcharging, so that a high capacity, high output secondary battery can be configured with a simple structure.
[0015]
The spacer in the above configuration is preferably made of anodized aluminum, or a resin made of a heat-resistant and electrolyte-resistant solution, or a metal coated with a heat-resistant and electrolyte-resistant resin, or made of ceramic. Thus, when a bulge occurs at the bottom of the outer case, the strength that suppresses the movement of the current collector plate following the swelling is obtained, and at the same time, a protrusion is formed between the bottom of the outer case and the one current collector plate. Can be configured so that only the welded portion is insulated from the other portions.
[0016]
Further, the sealing member is provided with an opening through which the electrode terminal penetrates and explosion-proof means for externally releasing abnormal internal pressure in the outer case, and a lid plate fixed to the opening end of the outer case at the peripheral edge, By providing a sealing means for sealing between the electrode terminals, an insulating means for insulating between the lid and the electrode terminals, and a fixing means for fixing the electrode terminals to the lid, a high capacity is provided. , The opening end of the outer case containing the high-power generating element can be securely sealed, and when the pressure inside the outer case rises abnormally, the explosion-proof means releases the abnormal inner pressure to the outside to prevent the rupture of the outer case can do.
[0017]
Further, by providing an insulating coating material for insulatingly covering the peripheral surface of the electrode plate group, insulation between the electrode plate group and the outer case can be reliably ensured and an internal short circuit can be prevented.
[0018]
In addition, by forming the cylindrical body in a cylindrical space formed at the center of the electrode group, the electrode group is deformed toward the cylindrical space when external pressure is applied to the outer case or due to internal pressure. Can be prevented from occurring.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. Note that the present embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0020]
FIG. 1 shows a configuration of a secondary battery 1 according to the present embodiment, which is configured as a lithium ion secondary battery. Electrode group 3 is accommodated together with the electrolytic solution in outer case 2 formed in a bottomed cylindrical shape, and a positive electrode plate connected to a positive electrode plate constituting electrode group 3 is provided on bottom 2 b side of outer case 2. A protruding portion 14 a provided on the power plate (one current collector) 14 is welded, and a spacer 4 is interposed between the positive current collector 14 and the bottom of the outer case 2. Further, on the other surface of the electrode plate group 3, a negative electrode current collector plate (the other current collector plate) 5 is provided so as to be connected to the negative electrode plate constituting the electrode plate group 3, and the negative electrode current collector plate 5 has a negative electrode terminal ( (Electrode terminals) 11 are joined. The open end of the outer case 2 exposes the negative electrode terminal 11 to the outside, and includes a cover plate 6, an O-ring (sealing means) 7, an insulating ring (insulating means) 8, and an insulating plate (insulating means) 9. Insulation between the lid plate 6 and the negative electrode terminal 11 is performed and sealing is performed by a sealing member 20 made of a material. The insulating sealing state is fixed by a push nut (fixing means) 10. Is fixed to the flange portion 2a. With this configuration, the secondary battery 1 has the outer case 2 as a positive electrode and the negative terminal 11 as a negative electrode.
[0021]
The electrode plate group 3 is formed in a cylindrical shape by winding a positive electrode plate and a negative electrode plate via a separator. Here, the positive electrode plate is formed by applying a positive electrode mixture containing lithium cobalt oxide as a positive electrode active material and polyvinylidene fluoride as a binder on both surfaces of a positive electrode core material formed of aluminum foil. Is formed. When the positive electrode mixture is applied to the positive electrode core material, the positive electrode mixture is not applied to the edge to which the positive electrode current collector plate 14 is joined, and the positive electrode core material is exposed to the edge. I do. In addition, the negative electrode plate is formed by applying a negative electrode mixture containing graphite as a negative electrode active material and polyvinylidene fluoride as a binder on both surfaces of a negative electrode core material formed of a copper foil. When the negative electrode mixture is applied to the negative electrode core material, the negative electrode mixture is not applied to the edge to which the negative electrode current collector plate 5 is joined, and the negative electrode core material is exposed to the edge. I do.
[0022]
When the electrode plate group 3 having the above configuration is accommodated in the outer case 2, the positive electrode current collector 14 is joined to one end face located on the bottom 2 b side of the outer case 2. As shown in FIG. 2, the positive electrode current collector plate 14 has a protrusion 14 a projecting toward the bottom 2 b on the surface of the outer case 2, which is on the bottom 2 b side, in the center of the disk, and A welding portion 14b projecting toward the group 3 is formed. As described above, since the positive electrode core material is exposed at one end of the positive electrode plate, when the positive electrode core material is wound and formed into the electrode plate group 3, the positive electrode plate is spirally wound on one end surface of the electrode plate group 3. The core is exposed. By pressing the welded portion 14b against the exposed positive electrode core material and welding the positive electrode core material and the welded portion 14b at a plurality of locations, the positive electrode current collector plate 14 has an internal resistance against the positive electrode plate of the electrode plate group 3. Are connected to less states.
[0023]
When the electrode plate group 3 is accommodated in the outer case 2, the negative electrode current collector 5 is joined to the other end face located on the opening end side of the outer case 2. As shown in FIG. 3, the negative electrode current collector plate 5 is formed with a welded portion 5 a that protrudes toward the electrode plate group 3 in the diameter direction, and has two cut-and-raised portions on the outer surface of the secondary battery 1. A portion 5b is formed. As described above, since the negative electrode core material is exposed at the other end of the negative electrode plate, when the negative electrode core material is wound and formed on the electrode plate group 3, the negative electrode plate is spirally wound around the other end surface of the electrode plate group 3. The core is exposed. By pressing the welded portion 5a against the exposed negative electrode core material and welding between the negative electrode core material and the welded portion 5a at a plurality of locations, the negative electrode current collector plate 5 has an internal resistance to the negative electrode plate of the electrode plate group 3. Are connected to less states. A flange 11a formed on the negative electrode terminal 11 is fitted and inserted under the cut-and-raised portion 5b, and the cut-and-raised portion 5b and the flange 11a are welded to each other. Electrical connection is made at the same time as the negative electrode terminal 11 is fixed.
[0024]
The outer case 2 is formed by forming an aluminum plate into a bottomed cylindrical shape by deep drawing, and also has an outwardly open flange portion 2a at an open end, as shown in FIGS. When the electrode group 3 in which the positive electrode current collector 14 and the negative electrode current collector 5 are joined to each other is inserted into the outer case 2, the spacer 4 is provided on the bottom 2 b side of the outer case 2.
[0025]
As shown in FIG. 2, the spacer 4 has an opening 4 a formed at the center thereof for passing a protrusion 14 a formed on the positive electrode current collector 14, and the thickness of the spacer 4 is the height of the protrusion 14 a. It is formed equivalently. The spacer 4 is required to have heat resistance and electrolyte resistance at the same time as being insulative. In this case, anodized aluminum is used. However, the spacer 4 is formed of a resin-coated metal or a resin or ceramic. You can also use what you have done.
[0026]
As described above, the spacer 4 is disposed on the bottom 2b of the outer case 2, and the electrode group 3 in which the positive electrode current collector 14 and the negative electrode current collector 5 are joined is inserted. Penetrates through the opening 4 a of the spacer 4, and the top comes into contact with the bottom 2 b of the outer case 2. Laser welding is performed between the abutting protruding portion 14a and the bottom 2b of the outer case 2 by laser light emitted from outside the bottom 2b. For this welding, electron beam welding can be applied. An electrolytic solution is injected into the outer case 2 accommodating the electrode group 3, and the electrode group 3 is impregnated with the electrolytic solution.
[0027]
The electrolyte solution is a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) or lithium borofluoride (LiBF ₄ ) as a solute, ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), or gamma-butyrolactone. (GBL), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and other non-aqueous solvents.
[0028]
As shown in FIG. 4, the opening of the outer case 2 containing the electrode group 3 impregnated with the electrolytic solution is sealed by a sealing member 20. In order to insulate and seal the outer case 2 from the negative electrode terminal 11, as shown in FIG. 5, an O-ring 7 is arranged on a step of the negative electrode terminal 11, and an insulating ring 8 is arranged. The cover plate 6 is arranged so as to compress the O-ring 7, the insulating plate 9 is arranged thereon, and finally the push nut 10 is crimped to the negative terminal 11. With this sealing structure, the negative electrode terminal 11 is insulated from the cover plate 6 by the cover plate 6 and the insulating ring 8 and the insulating plate 9, and the sealed state in which the negative electrode terminal 11 is exposed from the exterior case 2 to the outside is the O-ring 7. Maintained by
[0029]
As shown in FIGS. 6 (a) and 6 (b), the lid plate 6 closes an opening of the outer case 2 by caulking a thin portion 6a formed therearound to a flange 2a of the outer case 2. I do. First, as shown in FIG. 6A, primary caulking is performed to bend the thin portion 6a of the cover plate 6 so as to surround the flange portion 2a. Next, as shown in FIG. 6B, the opening of the outer case 2 is sealed by a secondary caulking process in which the thin portion 6a enclosing the flange portion 2a and the flange portion 2a are both bent. At this time, by applying a sealant to the peripheral surface of the thin portion 6a, a minute gap is also sealed, so that complete sealing is achieved.
[0030]
The cover plate 6 is provided with an explosion-proof valve 12 as shown in FIG. 4, and when the pressure in the sealed outer case 2 rises abnormally, the rise in the internal pressure proceeds even after the current cutoff mechanism described later is operated. In this case, the explosion-proof valve 12 is opened to release the abnormally increased internal pressure to the outside.
[0031]
When a failure occurs in the charge / discharge circuit or control circuit to which the secondary battery 1 having the above configuration is connected and the battery is exposed to overcharge or the like, the positive / negative electrode active material and the electrolytic solution are contained in the outer case 2. And the decomposition of the electrolytic solution occurs, and the pressure inside the outer case 2 abnormally rises due to the generation of gas. Since the outer case 2 has a cylindrical shape, the deformation mainly reaches the bottom 2b when the internal pressure increases.
[0032]
As shown in FIG. 7A, in a normal state, the bottom 2b is flat, but when the internal pressure of the outer case 2 rises abnormally, swelling occurs. Since the bottom 2b of the outer case 2 is welded to the projection 14a of the positive electrode current collector 14 at the center thereof, the swelling due to the increase in the internal pressure is centered around the welding point A as shown in FIG. It becomes a ring-shaped bulge. At this time, since the spacer 4 is provided between the positive electrode current collector 14 and the bottom 2b, the positive current collector 14 is prevented from moving following the outward bulge of the bottom 2b. As a result, a ring-shaped bulge as shown in FIG. When the pressure in the outer case 2 further increases, the height of the ring-shaped bulge increases, and the movement of the positive electrode current collector 14 is suppressed by the spacer 4, so that the space between the bottom 2b and the protrusion 14a at the welding point A is obtained. A force acts in a direction to break the welding. When the bulge of the bottom portion 2b exceeds the welding strength at the welding point A, the welding point A is broken and the bottom portion 2b becomes an arc-shaped bulge as shown in FIG.
[0033]
Since the joint between the projection 14a and the bottom 4b is broken at the welding point A, the electrical connection between the outer case 2 serving as a positive electrode terminal and the positive electrode current collector plate 14 is interrupted. 1 is released from a state such as overcharging. As a result, overcharging of the secondary battery 1 is stopped. However, when the internal pressure does not stop rising or when the internal pressure increases due to an increase in the battery temperature due to external heating, when the internal pressure increases to the limit state, the lid Since the explosion-proof valve 12 provided on the plate 6 is opened and the abnormal internal pressure is released to the outside, the state in which the secondary battery 1 ruptures is prevented.
[0034]
Causes of the battery falling into an abnormal state include mechanical or thermal factors in addition to the above-mentioned electrical factors such as overcharging, and in batteries with a high energy density such as lithium ion secondary batteries, It is necessary to ensure the accompanying safety. In particular, this is an important issue when configuring a high-capacity, high-output battery. In the secondary battery 1 according to the present embodiment, when the outer peripheral surface of the electrode group 3 is covered with an insulating material such as a heat-shrinkable tube, the electrode group 3 is deformed by the external pressure applied to the outer case 2. In addition, it is possible to prevent the negative electrode plate of the electrode plate group 3 from contacting the outer case 2 and causing an internal short circuit. Further, when the positive electrode plate and the negative electrode plate are wound in a cylindrical shape with a separator interposed therebetween, the cylindrical space generated in the center is a space in which the electrode plate group 3 is easily deformed by external pressure. It is preferable that an insulating cylindrical member is inserted into the cylindrical space to prevent deformation of the electrode plate group 3. The cylindrical member may be configured as a core for winding a positive electrode plate and a negative electrode plate via a separator.
[0035]
In the structure described above, the outer case 2 is made of aluminum to reduce the weight, but it can also be formed by deep drawing a nickel plated plate or a stainless plate. In this case, the negative electrode plate forming the electrode plate group 3 is connected to the outer case 2, the outer case 2 is used as a negative electrode, and the positive electrode plate forming the electrode plate group is connected to the electrode terminal serving as the negative electrode terminal 11. The terminal 11 is changed to a positive terminal.
[0036]
Although the present embodiment has been described with reference to an example in which the present invention is applied to a lithium ion secondary battery, it is effective to apply a similar configuration to a secondary battery or a primary battery such as a nickel-hydrogen storage battery.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to configure a secondary battery provided with a current interrupting function for interrupting a current circuit when a battery internal pressure is abnormally increased with a simple configuration, and the internal resistance increases due to the current interrupting function. Therefore, the present invention has an effect that is suitable for forming a high-capacity, high-output secondary battery constituting a power battery power supply such as an automobile power supply.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a secondary battery according to an embodiment.
FIG. 2 is a perspective view showing a configuration of a positive electrode current collector plate and a spacer.
FIG. 3 is a perspective view showing a configuration of a negative electrode current collector plate and a negative electrode terminal.
FIG. 4 is a perspective view showing a configuration of a sealing member.
FIG. 5 is a partial cross-sectional view showing a closing structure for closing an opening of the outer case.
FIG. 6 is a partial cross-sectional view showing a caulking structure between an outer case and a cover plate.
FIG. 7 is a sectional view showing the operation of the current interruption function in order.
FIG. 8 is a cross-sectional view showing a configuration of a current interruption mechanism according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Outer case 3 Electrode group 4 Spacer 5 Negative current collector (other current collector)
6 cover plate 7 O-ring (sealing means)
8 Insulation ring (insulation means)
9 Insulating plate (insulating means)
10. Push nut (fixing means)
11 Negative electrode terminal (electrode terminal)
14 Positive current collector (one side current collector)
20 Sealing member

Claims (8)

A positive electrode plate and a negative electrode plate are wound into a cylindrical shape via a separator to form an electrode plate group,
One end of the electrode plate group is connected to one of the positive electrode plate and the negative electrode plate, and a current collector plate having a projection formed in the center with a diameter substantially equal to the diameter of the electrode plate group is arranged,
At the other end of the electrode plate group, the other current collector plate provided with an electrode terminal at the center connected to one of the positive electrode plate or the negative electrode plate not connected to the one current collector plate is arranged,
The one current collector plate is provided with a spacer having a central opening formed to penetrate the protruding portion, and the poles are arranged such that the one current collector plate is located on the bottom side in an outer case formed in a bottomed cylindrical shape. The board group is housed,
The bottom of the outer case and the protrusion of the one current collector plate are welded together, the electrode group is impregnated with the electrolytic solution, and the open end of the outer case is sealed by a sealing member to expose the electrode terminals to the outside. A secondary battery characterized in that: The secondary battery according to claim 1, wherein the spacer is formed of anodized aluminum. The secondary battery according to claim 1, wherein the spacer is formed of a heat-resistant and electrolyte-resistant resin. The secondary battery according to claim 1, wherein the spacer is formed by coating a metal with a heat-resistant and electrolyte-resistant resin. The secondary battery according to claim 1, wherein the spacer is formed of ceramic. The sealing member is provided with an opening through which the electrode terminal is penetrated and explosion-proof means for externally releasing abnormal internal pressure in the outer case, and a lid plate fixed to the opening end of the outer case at a peripheral portion; 2. The sealing device according to claim 1, further comprising: a sealing means for sealing between the cover and the electrode, an insulating means for insulating between the lid and the electrode terminal, and a fixing means for fixing the electrode terminal to the lid. Next battery. The secondary battery according to claim 1, further comprising an insulating coating material that insulates a peripheral surface of the electrode group. The secondary battery according to claim 1, wherein a cylindrical body is inserted into a cylindrical space formed at a center portion of the electrode group.

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