WO2012164808A1

WO2012164808A1 - Rectangular secondary battery

Info

Publication number: WO2012164808A1
Application number: PCT/JP2012/002545
Authority: WO
Inventors: 尚士細川; 佑治大竹
Original assignee: パナソニック株式会社
Priority date: 2011-05-30
Filing date: 2012-04-12
Publication date: 2012-12-06
Also published as: JP2014149916A

Abstract

A rectangular secondary battery comprises: a flat electrode group having first and second end faces facing each other, in which a first collector plate having at least one through-hole is connected to the first end face; an electrolyte; a rectangular battery case having a bottom and housing the electrode group and the electrolyte; and a sealing plate sealing the battery case and having an explosion-proof valve. The first end face faces the sealing plate with the first collector plate in between, and the second end face faces the bottom portion of the battery case. In the rectangular secondary battery, at least part of the through-hole of the first collector plate is made to face the explosion-proof valve.

Description

Square secondary battery

The present invention relates to a bottomed prismatic battery case that houses an electrode group and a prismatic secondary battery that includes a sealing plate that seals the opening thereof, and is particularly provided on an end surface of the electrode group that faces the sealing plate. The present invention relates to the structure of the current collector plate.

In recent years, secondary batteries that can be used repeatedly have been used as power sources for driving portable electronic devices or mobile communication devices from the viewpoint of resource saving or energy saving. Further, such secondary batteries are being studied and put into practical use as a driving power source for vehicles and the like from the viewpoint of reducing the amount of fossil fuel used and the amount of carbon dioxide emitted.

In a secondary battery used as a power source for driving these vehicles, an exposed portion of a current collector sheet (core material) made of a metal foil of positive and negative electrodes is projected on opposite end faces of a wound or stacked electrode group. A structure for collecting current by connecting a current collecting plate to the portion by welding or the like (hereinafter referred to as an end face current collecting structure) is employed. By using the end face current collection structure, the current collection resistance of the secondary battery can be reduced, and the output of the secondary battery can be increased.

Various methods have been studied as a method of connecting the electrode and the current collector plate in the end face current collector structure. For example, it has been proposed to connect a current collector plate to a surface formed by bundling the current collector sheets of positive and negative electrodes (see Patent Documents 1 to 3).

Such an end face current collection structure can increase the contact area between the current collector sheet and the current collector plate, and is therefore advantageous in reducing the current collection resistance of the secondary battery. Output can be realized.

JP 2005-302719 A JP 2005-267945 A JP 2005-108535 A

As described above, when adopting a structure in which the current collector plate is installed on the end surface where the current collector sheets are bundled, increasing the current collector plate increases the contact area between the current collector sheet and the current collector plate. Therefore, the current collecting resistance can be further reduced. However, when the current collector plate is enlarged, there is a problem in that the current collector plate impedes discharge of gas generated in the electrode group.

In a secondary battery, when an abnormality such as overcharge occurs, the battery becomes hot, the active material and the electrolyte rapidly undergo a decomposition reaction, and a large amount of gas may be generated in the electrode group. Such gas is normally discharged from the end face of the electrode group to the outside of the electrode group. However, in the end face current collecting structure as described above, since the current collecting plate is installed on the end face of the electrode group, the discharge path of the gas generated inside the electrode group is obstructed. Therefore, the gas discharge efficiency decreases.

The above problem becomes apparent particularly in a prismatic secondary battery having a flat electrode group. In the cylindrical electrode group as shown in Patent Document 3, a space is usually provided at the center of the electrode group. Therefore, the gas generated inside the electrode group passes through this space and is discharged outside the electrode group. However, since such a space does not exist in the flat electrode group, it is difficult to discharge the gas generated inside the electrode group to the outside as compared with the cylindrical electrode group.

In addition, in a square type secondary battery such as Patent Documents 1 and 2, an electrode group in which positive and negative current collecting plates are installed on both end faces is housed in a bottomed case, and a seal provided with an explosion-proof valve for emergency The case is sealed with a plate. Both end faces of the electrode group are not opposed to the explosion-proof valve and have a relationship of forming an angle of 90 degrees. Therefore, after the gas generated inside the electrode group at the time of abnormality is exhausted from the end face of the electrode group, it must pass through the gap between the electrode group and the battery case, and follow a narrow path. And after finally reaching the explosion-proof valve, it is discharged outside the battery case.

In the structure of the prismatic secondary battery as described above, when a large amount of gas is generated inside the electrode group at the time of abnormality, the gas discharge is easily hindered by a narrow path between the electrode group and the battery case. Therefore, it is difficult for the gas generated inside the electrode group to be discharged, and there is a high possibility that the battery case is deformed due to an increase in the battery internal pressure.

The present invention has been made in view of the above, and an object of the present invention is to efficiently generate a large amount of gas generated inside the electrode group at the time of abnormality in a prismatic secondary battery having an end face current collecting structure. It is to discharge from the group to the outside and to the outside of the battery case.

The present invention has a flat electrode group, an electrolyte, and the electrode group each having a first end face and a second end face facing each other, and a first current collector plate having at least one through hole connected to the first end face. And a bottomed rectangular battery case that contains the electrolyte, and a sealing plate that seals the battery case and has an explosion-proof valve, and the first end surface is connected to the sealing plate via a first current collector plate. The second end face faces the bottom of the battery case, and the electrode group is formed by winding or laminating the first electrode and the second electrode with a separator interposed therebetween. The electrode includes a first core material and a first electrode mixture layer attached to the first core material, and the second electrode includes a second core material and a second electrode mixture attached to the second core material. And an end portion of the first electrode on the first end surface, and one end portion of the second electrode and The one end portion of the protruding first electrode is an exposed portion of the first current collector and is welded to the first current collector plate, and the first current collecting plate is welded to the first current collecting plate. The present invention relates to a prismatic secondary battery in which at least a part of the through hole of the electric plate is opposed to the explosion-proof valve.

The fact that at least a part of the through hole of the first current collector plate is opposed to the explosion proof valve is that when the through hole is viewed from the front of the explosion proof valve after the electrode group is stored in the battery case, This can be confirmed by at least partly overlapping at least part of the explosion-proof valve.

According to the present invention, the gas generated inside the electrode group at the time of abnormality passes through the shortest distance formed by the through hole and the explosion-proof valve formed in the first current collector plate and is discharged to the outside of the battery case. That is, even in the prismatic secondary battery having the end face current collecting structure, the discharge of the gas generated inside the electrode group at the time of abnormality is not hindered by the current collecting plate or the battery case.

While the novel features of the invention are set forth in the appended claims, the invention will be further described by reference to the following detailed description, taken in conjunction with the other objects and features of the invention, both in terms of construction and content. It will be well understood.

1 is an external perspective view of a prismatic secondary battery according to an embodiment of the present invention. It is the front view which made the cross section the case of the square secondary battery which concerns on one Embodiment of this invention. It is a figure which shows the positional relationship of the positive / negative electrode plate and separator of an electrode group which concern on one Embodiment of this invention. It is a perspective view of the 1st current collecting plate concerning one embodiment of the present invention. It is a top view of the 1st current collecting plate concerning one embodiment of the present invention. It is a disassembled perspective view which shows the internal structure of the square secondary battery which concerns on one Embodiment of this invention.

When the secondary battery is placed in an abnormal state such as overcharge, the temperature becomes high, the electrode active material and the electrolyte may rapidly decompose, and a large amount of gas may be generated from the inside of the electrode group. Such gas is normally discharged from the end face of the electrode group to the outside of the electrode group. However, in the case of a secondary battery adopting an end face current collecting structure, since the current collecting plate is installed on almost the entire end face of the electrode group, discharge of gas generated inside the electrode group is hindered by the current collecting plate, Emission efficiency decreases. Also, if the end face of the electrode group is not opposite to the explosion-proof valve, the gas generated inside the electrode group at the time of abnormality passes through a narrow path between the battery case and the electrode group and is discharged to the outside. As a result, the discharge efficiency also decreases.

Therefore, in the secondary battery of the present invention, a through hole is provided in a part of the first current collector plate, and at least a part of the through hole is opposed to the explosion-proof valve. As a result, when a large amount of gas is generated inside the electrode group at the time of abnormality, the shortest communication path that connects the outside of the battery case and the end face of the electrode group when the explosion-proof valve is activated due to the pressure increase in the battery case Is formed. A large amount of gas generated inside the electrode group can be efficiently discharged to the outside of the battery case through this communication path, and the expansion of the electrode group and the deformation of the battery case can be prevented in advance. .

That is, the prismatic secondary battery of the present invention has a flat first electrode having a first end face and a second end face facing each other, and a first current collector plate having at least one through hole connected to the first end face. And a bottomed square battery case for housing the group, electrolyte, electrode group and electrolyte, and a sealing plate for sealing the battery case and having an explosion-proof valve. The first end surface faces the sealing plate via the first current collector plate, and the second end surface faces the bottom of the battery case.

The electrode group is configured by winding or laminating the first electrode and the second electrode via a separator. The first electrode includes a first core material and a first electrode mixture layer attached to the first core material, and the second electrode includes a second core material and a second electrode mixture attached to the second core material. Agent layer. One end of the first electrode protrudes from the one end of the second electrode and one end of the separator at the first end surface, and the one end of the protruding first electrode does not have the first electrode mixture layer. It is an exposed part of the first current collector. The exposed portion of the first current collector is welded to the first current collector plate to constitute an end face current collection structure. And the through-hole of the 1st current collecting plate is provided in the position where the at least one part opposes the explosion-proof valve provided in the sealing board.

Here, the explosion-proof valve is a pressure release valve that opens when the pressure inside the battery rises and discharges the gas inside the battery to the outside. Generally, the material of the sealing plate is made thin. Provided. Therefore, it can be confirmed that at least a part of the through hole is opposed to the explosion-proof valve by at least a part of the through hole overlapping at least a part of the thin-walled region.

Here, the one end portion of the second electrode may protrude beyond the one end portion of the first electrode and the one end portion of the separator on the second end face of the electrode group. And the one end part of the protruding 2nd electrode is good also as an exposed part of the 2nd collector which does not have the 2nd electrode mixture layer. The exposed portion of the second current collector can be welded to the bottom of the battery case.

The electrode group may have a second current collector plate connected to the second end face thereof. In this case, the exposed portion of the second current collector may be welded to the second current collector plate, and the second current collector plate may be welded directly to the battery case or to the battery case via a lead piece or the like.

The shortest width of the through hole provided in the first current collector plate is preferably 1 mm or more, and more preferably 3 mm or more. By sufficiently securing the shortest width of the through hole, it is possible to prevent the through hole from being blocked even when the gas generated inside the electrode group at the time of abnormality includes a solid substance.

Gas generation can occur at various points in the electrode group. Therefore, the through hole is preferably formed in a region including the center of the first current collector plate. The explosion-proof valve is also preferably formed in a region including the center of the sealing plate corresponding to the position of the through hole. Furthermore, from the viewpoint of reliably operating the explosion-proof valve and ensuring a sufficient gas release path, the operation area of the explosion-proof valve is larger than the opening area of the through hole and is opposed to the entire opening area of the through hole. It is preferable.

The operation area of the explosion-proof valve is a part that preferentially deforms when the battery internal pressure rises. Therefore, when the explosion-proof valve is a thin portion provided on the sealing plate, the area of the thin portion is the operating area. However, the entire working area need not be opened or cleaved. For example, a part of the thin portion may be opened or cleaved.

In a preferred embodiment of the present invention, the first current collector plate has a strip shape in which both short sides are rounded, and at least a part of the short sides and both sides of the through hole are on the first end face side. Has a convex surface. The convex surface is in surface contact with the first end surface, and at least a part of the convex surface is welded to the exposed portion of the core material of the first electrode disposed on the first end surface. In such a structure, a gap is formed between the peripheral edge portion of the through hole and the first end surface.

Next, an embodiment of the present invention will be described with reference to the drawings. However, the following embodiments are merely illustrative of the prismatic secondary battery and the components thereof of the present invention, and the present invention is not limited to the following embodiments.

FIG. 1A is an external perspective view of a prismatic secondary battery according to an embodiment of the present invention, and FIG. 1B is a front view in cross section of the same secondary battery case.
The prismatic secondary battery 100 according to the present invention has a rectangular shape or a rectangular shape as viewed from the front, and has a flat shape with a smaller thickness than its width and height. Inside the battery case 1, a flat electrode group 13 having a first end face and a second end face facing each other as shown in FIG. 1B is housed together with an electrolyte (not shown). The electrode group 13 is configured by winding the first electrode 15 and the second electrode 17 through a separator 19. The shape of the electrode group 13 is also flat, and the shapes of the first end face and the second end face perpendicular to the winding axis are substantially elliptical.

The opening of the battery case 1 is sealed by a sealing plate 3 having an explosion-proof valve 5. A first current collecting plate 21 having a through hole 23 is connected to the first end face of the electrode group 13, and the first current collecting plate 21 faces the sealing plate 3. On the other hand, the second end face of the electrode group 13 faces the bottom of the battery case 1. Since the sealing plate 3 is welded to the opening end of the battery case 1, the battery case 1 and the sealing plate 3 have the same polarity.

FIG. 2 is a diagram showing a positional relationship between the positive electrode plate, the negative electrode plate, and the separator of the electrode group according to the embodiment of the present invention.
The first electrode 15 includes a strip-shaped first core material and a first electrode mixture layer 15b attached to the first core material, and the second electrode 17 includes a strip-shaped second core material and a second core material. And the second electrode mixture layer 17b attached to the substrate. However, one end portion along the longitudinal direction L of the first electrode 15 protrudes from one end portion of the second electrode 17 and one end portion of the separator 19, and the one end portion along the longitudinal direction L of the second electrode 17 It protrudes from one end of one electrode 15 and one end of the separator 19. That is, one end of the positive electrode plate 15 and one end of the negative electrode plate 17 protrude from the separator 19 in opposite directions.

An exposed portion 15a of the first core material that does not have the first electrode mixture layer 15b is provided at one end portion of the protruding first electrode 15. Similarly, an exposed portion 17a of the second core member that does not have the second electrode mixture layer 17b is provided at one end portion of the protruding second electrode 17. The exposed portion 15 a of the first core material protrudes in a spiral shape from the first end surface of the electrode group 13, and the exposed portion 17 a of the second core material protrudes in a spiral shape from the second end surface of the electrode group 13.

The end face current collecting structure is formed by welding the first current collecting plate 21 to the first end face where the exposed portion 15a of the first core member is present. On the other hand, a similar end face current collecting structure is formed on the second end face where the exposed portion 17 a of the second core member is present by welding to the bottom of the battery case 1.

A current collector plate (second current collector plate) may be welded to the second end surface where the exposed portion 17a of the second core member is present, like the first end surface. In this case, the battery collector 1 and the sealing plate 3 are made to have the same polarity as the second electrode 17 by welding the second current collector plate directly to the battery case or by welding it to the battery case via a lead piece or the like. can do.

Here, the through hole 23 provided in the first current collector plate 21 is positioned so that at least a part thereof is opposed to the explosion-proof valve 5 provided in the sealing plate 3. The explosion-proof valve 5 opens to release the internal pressure when the internal pressure of the battery case 1 increases. Therefore, the gas generated inside the electrode group at the time of abnormality passes through the shortest distance formed by the through hole 23 and the explosion-proof valve 5 and is discharged to the outside of the battery case 1. That is, a decrease in gas discharge efficiency that obstructs the first current collecting plate 21 is suppressed to a minimum. Therefore, even in the prismatic secondary battery adopting the end face current collecting structure, the gas generated inside the electrode group can be smoothly discharged to the outside. Therefore, it is possible to prevent the electrode group 13 and the battery case 1 from expanding and deforming.

The configuration of the explosion-proof valve 5 is not particularly limited, but in FIG. 1, it is provided by forming a part of the sealing plate 3 thin. When the battery internal pressure exceeds the set upper limit, the thickness of the thin portion is adjusted so as to be opened or cleaved. You may form the groove | channel and recessed part which promote cleavage in a thin part. The through hole 23 is formed in a region including the center of the first current collector plate 21, and the explosion-proof valve 5 is also formed in a region including the center of the sealing plate 3.

A first external terminal 9 electrically connected to the first current collector plate 21 is provided at a position closer to one side than the explosion-proof valve 5 in the longitudinal direction of the sealing plate 3, and a position closer to the other side is provided. A second external terminal 7 having the same polarity as the sealing plate 3 is provided. Since the sealing plate 3 has the same polarity as the first electrode 15, the first external terminal 9 is inserted into the sealing plate 3 through a pipe 11 made of an insulating member such as a gasket.

The second external terminal 7 is formed by using a liquid injection port for injecting an electrolyte into the battery case 1. When the injection of the electrolyte is finished, the injection port is sealed with a plug and can be used as the second external terminal 7.

FIG. 3A is a perspective view showing an example of a first current collector plate, and FIG. 3B is a top view of the same first current collector plate. FIG. 4 is an exploded perspective view showing the structure near the first end face of the electrode group.

The first current collecting plate 21 includes a flat base portion 25, a first protrusion 27 that protrudes from the base portion 25 toward the first end surface, and a second protrusion that protrudes toward the sealing plate 3 side. 28. At least one through hole 23 is formed in the base material portion 25. The convex surface (preferably flat surface) of the first protrusion 27 is in surface contact with the first end surface of the electrode group 13, and at least a part of the convex surface of the first electrode 15 disposed on the first end surface. It is welded to the exposed portion 15a of the core material by laser welding or the like. The first protrusion 27 is preferably formed in a rib shape so as to extend substantially perpendicular to the edge of the exposed portion 15 a of the core material of the first electrode 15 on the first end face of the electrode group 13.

The convex surface of the second projecting portion 28 is convex in the opposite direction to the first projecting portion 27, and the height from the base material portion 25 is also higher than that of the first projecting portion 27. The first external terminal 9 is fixed to the sealing plate 3 in a state of penetrating the sealing plate 3, and the distal end portion of the first external terminal 9 is inserted into the terminal hole 28 a of the second protruding portion 28, thereby One current collecting plate 21 is fixed in a state where a certain distance from the sealing plate 3 is maintained. Note that the tip end portion of the first external terminal 9 may be formed in a screw shape, and a screw groove may be provided on the inner surface of the terminal hole 28a.

More specifically, the first current collecting plate 21 has a strip shape in which both short sides are rounded, and the first end face side is provided on at least a part of the short sides and both sides of the through hole 23. A first protrusion 27 having a flat surface is formed. According to such a structure, a sufficient contact area between the first end surface and the first current collector plate 21 can be ensured, and at the peripheral portion of the through hole 23, the first current collector plate 21 and the first end surface are disposed. A void can be formed in the surface. This gap advantageously acts on gas movement when the gas is discharged from the inside of the electrode group 13 to the outside.

The position of the 1st protrusion part 27 in the negative electrode current collecting plate 21 is not limited to the position shown in FIG. Moreover, the number of the 1st protrusion parts 27 is not specifically limited, either. Furthermore, the cross-sectional shape of the protrusion 27 is not limited to a trapezoid with a flat top surface as shown in FIG. For example, the cross-sectional shape may be a polygon other than a trapezoid, may be a substantially semicircle, or may be a shape including a straight line portion and an arc portion. However, the protrusion 27 having a trapezoidal cross-sectional shape can be easily formed, and the connection strength between the protrusion 27 and the first end surface can be easily secured.

As the material of the first current collector plate 21, a material known as a positive electrode or a negative electrode current collector plate of a secondary battery can be used without any particular limitation. For example, copper, a copper alloy, nickel, a nickel alloy, or the like can be used for the negative electrode current collector plate. Moreover, iron, nickel, a nickel alloy, etc. can be used for a positive electrode current collecting plate. The thickness of the first current collector plate is not particularly limited, but may be, for example, 100 μm to 1000 μm.

Although the through-hole 23 should just be formed in at least one part of the base material part 25 of the 1st current collecting plate 21, when the through-hole 23 is seen from right above the explosion-proof valve 5, as shown in FIG. The through hole 23 is formed at a position where at least a part of the through hole 23 overlaps the explosion-proof valve 5. By forming the through hole 23 at such a position, a communication path that connects the explosion-proof valve 5, the through hole 23, and the first end face of the electrode group 13 with the shortest distance is formed, and gas generated inside the electrode group is efficiently generated. Thus, it can be discharged outside the battery case.

In FIG. 4, the operating area of the explosion-proof valve 5 (thin wall area) is larger than the opening area of the through hole 23, and the operating area of the explosion-proof valve 5 (thin wall area) is the entire opening area of the through hole 23. Is opposite. Since the explosion-proof valve 5 and the through-hole 23 have such a relationship, the explosion-proof valve can be reliably operated and a sufficient gas discharge path can be secured.

Although the through hole 23 can be formed in a part of the first protrusion 27 of the first current collector plate 21, the first protrusion 27 is a region connected to the first end face of the electrode group 13 by welding. . Therefore, it is better not to provide the through hole 23 in the first projecting portion 27 from the viewpoint of improving the reliability of the welded portion.

The through hole 23 is formed in a region including the center of the first current collector plate in FIG. 1, and the explosion-proof valve 5 is also formed in a region including the center of the sealing plate 3 in FIG. The position is not limited to this. Moreover, the through-hole 23 should just be a shape which can pass the gas generate | occur | produced inside the electrode group, and the shape is not limited to a substantially elliptical shape as shown in FIG. For example, a perfect circular or rectangular through hole may be provided. Further, the number of through holes 23 is not particularly limited. Regardless of whether the number of through holes 23 is one or more, it is considered that substantially the same effect can be obtained.

However, the shortest width of the through hole is preferably 1 mm or more, and more preferably 3 mm or more. By setting the shortest width of the through hole to 1 mm or more, a sufficient area of the through hole can be ensured, and the gas generated inside the electrode group at the time of abnormality can be more easily discharged. In addition, solids may be mixed in the gas generated at the time of abnormality. By setting the shortest width of the through-hole to 1 mm or more, the through-hole 23 is prevented from being blocked by the solid. Can do. However, if the shortest width is too large, the strength of the first current collector plate 21 may be insufficient. Therefore, it is desirable to design the size (opening area) of the through-hole 23 in consideration of the strength and energization performance of the first current collecting plate 21.

The peripheral part of the through hole 23 of the first current collecting plate 21 has a small cross-sectional area, and stress and current tend to concentrate. Therefore, although depending on the material and thickness of the first current collector plate 21, the cross-sectional area of the portion where the through hole 23 is provided in the cross section perpendicular to the longitudinal direction of the first current collector plate is the cross section including the through hole 23. It is preferable to be 80% or less of the whole.

The method for producing the first current collector plate 21 is not particularly limited. For example, the first current collecting plate 21 may be collectively formed by a press forming method, or may be bent. The through hole 23 may be provided at the end of the manufacturing process of the first current collector plate 21, or after the through hole is formed in the base material that is the material of the first current collector plate 21, the base material is processed. The first current collecting plate 21 may be used. Further, when the first current collecting plate 21 is formed, the through holes 23 may be formed at the same time. As a method for forming the through hole 23, a general method such as cutting, laser processing, or electric discharge machining can be used.

The projected area of the first current collecting plate on the first end face of the electrode group is preferably smaller than the area of the first end face, and is 95% or less of the area of the first end face. It is desirable from the viewpoint of preventing a short circuit with the plate. However, from the viewpoint of securing the contact area between the first current collecting plate 21 and the electrode core and the number of welding points, the projected area of the first current collecting plate on the first end face of the electrode group is 80 of the first end face of the electrode group. % Or more is preferable. By using such a first current collector plate, a sufficient contact area and the number of welding points can be ensured, and the connection resistance between the first current collector plate 21 and the electrode core material can be reduced.

An insulating plate (not shown) such as a resin member may be disposed between the first current collecting plate 21 and the sealing plate 3 from the viewpoint of more reliably preventing an internal short circuit. Further, in order to ensure insulation between the battery collector 1 and the exposed portion 15a of the core material of the first current collector plate 21 and the first electrode 15, the core material of the first current collector plate 21 and the first electrode 15 is exposed. An insulating material such as a resin member may be disposed so as to surround the portion 15a.

The secondary battery may be a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, or an aqueous battery such as a nickel metal hydride secondary battery. As materials and structures of the positive electrode plate, the negative electrode plate, the separator, and the electrolyte, which are constituent elements of the secondary battery, known materials and structures can be employed without any particular limitation. Further, the structure of the positive electrode plate and the negative electrode plate, for example, the thickness of the electrode core material, the thickness of the electrode mixture layer, the content of each component in the electrode mixture layer, etc. is not particularly limited, and is within a known range. I just need it. The electrode group 13 may have a stacked structure in which a plurality of positive plates and a plurality of negative plates are stacked via a separator.

The first electrode may be a positive electrode plate or a negative electrode plate. If the first electrode is a negative electrode plate, the battery case and the sealing plate are connected to the positive electrode plate, and thus have a positive polarity, and the first external terminal 9 has a negative polarity. On the other hand, if the first electrode is a positive electrode plate, the battery case and the sealing plate are connected to the negative electrode plate, and thus have a negative polarity, and the first external terminal 9 has a positive polarity.

As described above, the present invention is useful as a power source for driving portable electronic devices, mobile communication devices or vehicles.

Although the present invention has been described in terms of the presently preferred embodiments, such disclosure should not be construed as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains after reading the above disclosure. Accordingly, the appended claims should be construed to include all variations and modifications without departing from the true spirit and scope of this invention.

1: battery case, 3: sealing plate, 5: explosion-proof valve, 7: injection port (second external terminal), 9: first external terminal, 11: pipe, 13: electrode group, 15: first electrode, 15a: exposed portion of the first current collector, 15b: first electrode mixture layer, 17: second electrode, 17a: exposed portion of the second current collector, 17b: second electrode mixture layer, 19: separator, 21, first current collector plate, 23: through hole, 25: base material portion, 27: first protruding portion, 28: second protruding portion, 28a: terminal hole

Claims

A flat electrode group having a first end face and a second end face facing each other, and a first current collector plate having at least one through hole connected to the first end face, an electrolyte, and the electrode group and the electrolyte A bottomed rectangular battery case to be housed, and a sealing plate for sealing the battery case and having an explosion-proof valve;
The first end surface is opposed to the sealing plate via a first current collector plate, and the second end surface is opposed to the bottom of the battery case,
The electrode group is formed by winding or laminating a first electrode and a second electrode via a separator, and the first electrode includes a first core material and a first electrode attached to the first core material. Including a mixture layer, and the second electrode includes a second core material and a second electrode mixture layer attached to the second core material,
One end portion of the first electrode protrudes from the one end portion of the second electrode and one end portion of the separator at the first end surface, and the one end portion of the protruding first electrode is protruded from the first current collector. An exposed portion of the first current collector welded to the plate,
A prismatic secondary battery, wherein at least a part of the through hole of the first current collector plate faces the explosion-proof valve.
The one end of the second electrode protrudes from the one end of the first electrode and the one end of the separator at the second end surface, and the one end of the protruding second electrode is the bottom of the battery case. The prismatic secondary battery according to claim 1, which is an exposed portion of the second current collector welded to the second current collector.
The electrode group includes a second current collector plate connected to the second end face,
One end portion of the second electrode protrudes from the one end portion of the first electrode and one end portion of the separator at the second end surface, and the one end portion of the protruding second electrode is the second current collector. The prismatic secondary battery according to claim 1, which is an exposed portion of the second current collector welded to a plate.
The prismatic secondary battery according to any one of claims 1 to 3, wherein a minimum width of the through hole is 1 mm or more.
The at least one through hole is formed in a region including the center of the first current collector plate,
The explosion-proof valve is formed in a region including the center of the sealing plate,
The square two-dimensional structure according to any one of claims 1 to 4, wherein an operating area of the explosion-proof valve is larger than an opening area of the through hole and is opposed to the entire opening area of the through hole. Next battery.
The first current collector plate has a strip shape with a short side portion rounded, and has a convex surface on the first end face side on at least a part of the short side portion and on both sides of the through hole. The convex surface is in surface contact with the first end surface;
The prismatic secondary battery according to any one of claims 1 to 5, wherein a gap is formed between a peripheral edge portion of the through hole and the first end surface.