WO2012133329A1

WO2012133329A1 - Method for manufacturing rectangular secondary battery

Info

Publication number: WO2012133329A1
Application number: PCT/JP2012/057779
Authority: WO
Inventors: 佑介富松; 毅典木村; 山西　伸和
Original assignee: 三洋電機株式会社
Priority date: 2011-03-31
Filing date: 2012-03-26
Publication date: 2012-10-04
Also published as: JPWO2012133329A1; JP6072676B2

Abstract

[Problem] To provide a method for manufacturing a highly reliable rectangular secondary battery in which an intermediate conductive member is disposed between stacked core-body exposed portions obtained by being divided into two and even if spattered dust occurs between a collector member and a welding electrode during resistance welding, the dust is seldom released into the outside. [Solution] At least one of a positive electrode core-body exposed portion (14) and a negative electrode core-body exposed portion is divided into two groups and at least one intermediate conductive member (24) having protrusions formed thereon is disposed between the two groups. A collector member (16) having projections projecting to the side of the intermediate conductive member (24) are disposed so that the projections face the protrusions provided on the intermediate conductive member (24) with the core-body exposed portion (14) interposed therebetween. The stacked core-body exposed portion (14) is pressed from both sides thereof by a pair of resistance welding electrodes (31) each having a resistance welding face having a larger diameter than the diameter of the projections provided on the collector member (16), and resistance welding is performed while parts of the projections contact the resistance welding faces of the resistance welding electrodes.

Description

Method for manufacturing prismatic secondary battery

The present invention relates to a method for manufacturing a prismatic secondary battery having a core exposed portion that is laminated and divided into two. Specifically, in the present invention, at least one of the laminated positive electrode core exposed portion and negative electrode core exposed portion is divided into two, and an intermediate conductive member is disposed between the two divided core exposed portions, and the core The present invention relates to a method for manufacturing a rectangular secondary battery having a current collecting structure in which a resistance welding is performed between an exposed portion and a current collecting member and between a core exposed portion and an intermediate conductive member.

In recent years, environmental protection movements have increased, and emission regulations that cause global warming, such as carbon dioxide gas, have been strengthened. Therefore, in the automobile industry, electric vehicles (EV) and hybrid electric vehicles (HEV) are actively developed in place of vehicles using fossil fuels such as gasoline, diesel oil, and natural gas. As such EV and HEV batteries, nickel-hydrogen secondary batteries and lithium ion secondary batteries are used. However, in recent years, a lightweight and high capacity battery can be obtained. Non-aqueous electrolyte secondary batteries such as secondary batteries are increasingly used.

In EV and HEV applications, it is necessary not only to respond to the environment, but also to improve the basic performance as an automobile, that is, the driving performance such as acceleration performance and climbing performance. In order to satisfy such a demand, not only simply increasing the battery capacity but also a high output battery is required. In general, non-aqueous electrolyte secondary batteries for EV and HEV use a lot of prismatic secondary batteries in which a power generation element is housed in a rectangular outer can made of an aluminum-based metal. Therefore, it is necessary to reduce the internal resistance of the battery as much as possible. For this reason, various improvements have been made to reduce the internal resistance by preventing poor welding between the positive electrode plate or the negative electrode plate core of the battery power generation element and the current collecting member.

There are mechanical caulking methods, welding methods, etc. as a method of collecting electricity by electrically connecting the core exposed portion of the electrode plate of the power generating element and the current collecting member, but for batteries that require high output. As a current collecting method, a welding method is suitable because it is easy to realize low resistance and hardly changes with time. However, an electrode body of a square sealed secondary battery such as a lithium ion secondary battery for EV and HEV has a configuration in which a positive electrode plate and a negative electrode plate are stacked or wound via a separator. The core body exposed portions of the positive electrode plate or the negative electrode plate are arranged to be located on different sides, respectively, and the core body exposed portions of the positive electrode plate are laminated and welded to the positive electrode current collector member. The core exposed portion of the plate is also laminated and welded to the negative electrode current collector. The number of stacked positive electrode core exposed portions and negative electrode core exposed portions is very large when the capacity of a square sealed secondary battery such as a lithium ion secondary battery for EV and HEV is large.

On the other hand, in Patent Document 1 below, in the electrode body in which the positive electrode plate and the negative electrode plate are wound in a flat shape with a separator interposed therebetween, the lamination width of the core exposed portion of each electrode protruding from the separator is reduced. In order to do this, an invention of an electricity storage element in which the core exposed portion of each electrode is divided into two portions and welded to a current collecting member is disclosed. Here, a configuration of a power storage element disclosed in Patent Document 1 described below will be described with reference to FIGS. 8A is a cross-sectional view of an electric double layer capacitor as a power storage element disclosed in Patent Document 1 below, FIG. 8B is a cross-sectional view taken along line VIIIB-VIIIB of FIG. 8A, and FIG. 8C is a cross-sectional view of FIG. FIG. 8 is a sectional view taken along line VIIIC-VIIIC. Moreover, FIG. 9 is a figure which shows the welding process between the core exposed part of an electrode in FIG. 8, and a current collection member.

As shown in FIGS. 8A to 8C, the power storage device 50 includes a wound electrode body 51 in which a positive electrode plate and a negative electrode plate are stacked via a separator (both not shown) and wound in a flat shape. The wound electrode body 51 is disposed in a rectangular aluminum outer can 52. Further, each of the positive electrode current collecting member 53a and the negative electrode current collecting member 53b of the electric storage element 50 is formed with U-shaped wing parts 54a to 54b at one end, respectively, and the core of the positive electrode plate. The exposed portion 55a is connected to the core exposed portion 55b of the negative electrode plate, and the other end is connected to the positive terminal 56a or the negative terminal 56b. The core body exposed portion 55a of the positive electrode plate is bundled and divided into two parts, which are welded to two locations on the outer surface side of one U-shaped wing portion 54a, respectively. The part 55b is also divided into two parts and welded to two locations on the outer surface side of the other U-shaped wing part 54b.

For example, if this welding is on the positive electrode plate side, as shown in FIG. 9, one of the core body exposed portions 55a of the positive electrode plate divided into two is arranged on the outer surface of the U-shaped wing portion 54a. Then, the horn 57 of an ultrasonic welding device (not shown) is brought into contact with the outer surface of the core exposed portion 55a, and the anvil 58 is disposed on the inner surface side of the U-shaped wing portion 54a, so that ultrasonic welding is performed. Has been done. In addition, ultrasonic welding is performed by the same method with respect to the other of the core exposed portions 55a of the two divided positive electrode plates, and the same applies to the negative electrode plate side.

On the other hand, in the case of resistance welding of the core exposed portions that are laminated and divided into two, a method of welding the divided core exposed portions one side at a time or series spot welding in which the divided core exposed portions are simultaneously welded are considered. However, series spot welding is preferable in consideration of reduction in the number of weldings. In the conventional series spot welding technique, as shown in FIG. 10, when welding the

welded members

73 and 74 at two points coaxially with a pair of

resistance welding electrodes

71 and 72, a U-shape A method of welding the upper and lower sides of the U-shaped welding part 75 with the welding part 75 in the middle interposed between them is mainly used. This method is widely used because the U-shaped welding part 75 can be easily manufactured from a plate-shaped metal plate, and because it is easy to produce a projection for easily and stabilizing resistance welding. Yes.

JP 2003-249423 A Japanese Utility Model Publication No.58-113268

According to the invention disclosed in Patent Document 1, since the exposed widths of the positive electrode core exposed portion and the negative electrode core exposed portion can be reduced, the volume efficiency of the power storage device is improved. However, in the present invention, in order to weld the positive electrode current collecting member or the negative electrode current collecting member to the positive electrode plate or the negative electrode plate, a plurality of times of welding are required, and further, a U-shape is formed during ultrasonic welding. There is a problem that the manufacturing equipment becomes complicated, such as the need to arrange an anvil inside the wing part.

Moreover, although the said patent document 1 describes that it is especially preferable to use an ultrasonic welding process for the process of connecting an electrode electrode plate, the winding number in an Example is 16 times (it is 8 in one side divided into 2 parts). The lamination thickness is 320 μm. On the other hand, in a prismatic secondary battery having a large capacity, such as a lithium ion secondary battery for EV and HEV, the number of stacked positive electrode core exposed portions and negative electrode core exposed portions is that of the invention disclosed in Patent Document 1 above. It is much more than the case, and the lamination thickness is much thicker.

Therefore, in a square sealed secondary battery having a large capacity, such as a lithium ion secondary battery for EV and HEV, superposition as a welding method between the stacked positive electrode core exposed portion and the negative electrode core exposed portion and the current collecting member is super. In order to weld in a stable state by adopting the sonic welding method, large pressurization and ultrasonic vibration are used to bring the stacked positive electrode core exposed portion and negative electrode core exposed portion into close contact with the current collecting member. Large energy is required to reach the other end side of the stacked positive electrode core exposed portion and negative electrode core exposed portion. In the invention disclosed in the above-mentioned Patent Document 1, since it is necessary to receive pressure and ultrasonic energy with the anvil disposed inside the U-shaped current collecting member, the anvil needs to have appropriate rigidity, It is technically very difficult to find a more stable welding condition while receiving a large pressure with an anvil having a size that can be supplied to the inside of the U-shaped current collecting member.

In the conventional method shown in FIG. 10, each of the positive electrode core exposed portion and the negative electrode core exposed portion can be series-welded by one-time welding. In order to eliminate the distortion of the U-shaped welding part 75, it is necessary to take measures such as supplying and taking out the pressure receiver 76 and the metal block for energization inside the U-shaped welding part.

In Patent Document 2, as shown in FIG. 11,

electrode core groups

84a and 84b in which the core body 84 of the electrode body 83 is divided into two parts on both sides of the base portion 82 of the current collecting member 81 and converged. The electrode plate core assembly apparatus 80 is shown in which a series spot welding is performed together with a pair of

contact plates

85a and 85b disposed outside the

electrode core groups

84a and 84b.

However, in the series spot welding method disclosed in Patent Document 2, the core exposed portion of the positive electrode plate or the negative electrode plate is divided into two and is directly series spot welded from both sides of the positive electrode terminal or the negative electrode terminal. However, since the welding surface of the positive electrode terminal or the negative electrode terminal is a flat surface, the welding strength between the positive electrode terminal or the negative electrode terminal and the exposed portion of the positive electrode plate or the core body of the negative electrode plate is increased, and It was difficult to reduce variations in internal resistance. *

In the case of a square sealed secondary battery having a large capacity, such as a lithium ion secondary battery for EV and HEV, the number of stacked positive electrode core exposed portions and negative electrode core exposed portions is extremely large, and the positive electrode core Aluminum or an aluminum alloy is used as the body and the positive electrode current collector, and copper or a copper alloy is used as the negative electrode core and the negative electrode current collector. Since these aluminum or aluminum alloy, copper or copper alloy is a material having low electrical resistance and good thermal conductivity, between the positive electrode core exposed portion and the positive electrode current collector and the negative electrode core exposed portion A large amount of welding energy is required to reliably weld the negative electrode current collecting member to increase the welding strength and reduce the internal resistance of the welded portion. In addition, if the welding energy is increased during resistance welding, the amount of sputtered dust generated increases, but this dust moves into the electrode body, causing internal short circuits or defective pressure resistance, leading to a decrease in manufacturing yield. become.

The present invention has been made to solve the above-described problems of the prior art, and the core exposed portion on at least one side of the stacked positive electrode core exposed portion and negative electrode core exposed portion is divided into two. Manufacturing of a prismatic secondary battery having a current collecting structure in which an intermediate conductive member is disposed between the core exposed portion and the current collecting member and between the core exposed portion and the intermediate conductive member is resistance-welded. An object of the present invention is to provide a method for manufacturing a prismatic secondary battery that can reduce the resistance of a welded portion and can reduce the amount of spatter generated during resistance welding.

In order to achieve the above object, a method for manufacturing a prismatic secondary battery according to the present invention includes: a current collecting member corresponding to each of a stacked positive electrode core exposed portion and a negative electrode core exposed portion of a stacked or wound electrode body; A method of manufacturing a prismatic secondary battery having a connected current collecting structure, the step of dividing at least one of the stacked positive electrode core exposed portion and negative electrode core exposed portion into two, Between the core exposed portions, at least one intermediate conductive member having a convex portion formed on the side in contact with the two-divided core exposed portions is disposed, and the outermost core exposed portion on the two split sides is disposed. A current collecting member having a protruding portion on the outer conductive surface on the side of the intermediate conductive member, the protruding portion having a diameter larger than the diameter of the protruding portion provided on the intermediate conductive member, and the protruding portion provided on the intermediate conductive member. To be placed so as to face each other through the core exposed part The pair of resistance welding electrodes having a resistance welding surface having a diameter larger than the diameter of the protruding portion provided on the current collecting member are pressed from both sides of the laminated core exposed portion, and a part of the protruding portion is A step of performing resistance welding while being in contact with a resistance welding surface of the electrode for resistance welding.

The current collecting member on the side of the core body exposed portion divided into two parts of the present invention may be disposed on at least one outermost surface of the core body exposed part divided into two parts. It is preferable to arrange on both outermost surfaces of the body exposed portion. However, even if a current collecting receiving member that is not directly connected to the electrode terminal is disposed on the other outermost surface of the two-divided core exposed portion, the current collecting member is substantially divided into two. The same effect as the case where it arrange | positions on both the outermost surfaces of a core exposure part can be show | played. Therefore, the “current collecting member” in the present invention is used to include such a “current collecting member”.

In the method for manufacturing a prismatic secondary battery of the present invention, for example, when current collecting members are arranged on both outermost surfaces of the core exposed portion which is laminated and divided into two, the current during resistance welding is the resistance of one resistance Electrode for welding → one current collecting member → one of the two exposed core bodies → one convex part of the intermediate conductive member → main part of the intermediate conductive member → the other convex part of the intermediate conductive member → two splits The other side of the core exposed portion on the formed side → the other current collecting member → the other resistance welding electrode, so that one current collecting member, one side of the core exposed portion divided into two and the intermediate conductive member Series welding is simultaneously performed between the other convex portion of the intermediate conductive member and the other convex portion of the intermediate conductive member and the other of the two exposed core bodies and the other current collecting member. In addition, since the convex portion of the intermediate conductive member and the protrusion provided on the current collecting member both act as projections, there is a large amount in the core exposed portion disposed between the intermediate conductive member and the current collecting member during resistance welding. Since the nugget is formed, the welding strength is increased. In the present invention, one current collecting member and the other current collecting member may be integrally formed.

Moreover, since the diameter of the resistance welding surface of the resistance welding electrode (tip surface in contact with the current collecting member) is larger than the diameter of the protruding portion provided on the current collecting member, the resistance welding electrode is connected to the protruding portion of the current collecting member. When abutting from the side opposite to the top, a sealed gap is formed between the tip of the resistance welding electrode and the protruding portion of the current collecting member. On the other hand, at the time of resistance welding, the top portion of the protruding portion of the current collecting member is opposed to the convex portion of the intermediate conductive member with the core body exposed portion on the side divided into two. For this reason, when the pair of resistance welding electrodes are pressed against each other, the projecting portion of the current collecting member and the core exposed portion divided into two parts are deformed toward the distal end side of the resistance welding electrode by the convex portion of the intermediate conductive member. The projecting portion of the deformed current collecting member is in contact with the resistance welding surface of the resistance welding electrode. In addition, the air gap formed between the protruding portion of the current collecting member and the tip of the resistance welding electrode remains in a sealed state on the outer peripheral wall side of the protruding portion of the current collecting member, and its volume is small. Become.

If resistance welding is performed in this state, the contact state between the current collecting member and the resistance welding surface of the resistance welding electrode becomes good, and thus sputtering is less likely to occur. In addition, since the current collecting member has a smaller heat capacity than the resistance welding electrode, the surface of the current collecting member is hotter during resistance welding, and the current collecting member has a gap between the protruding portion of the current collecting member and the tip of the resistance welding electrode. Since the formed gap is hermetically sealed, the sputtered dust is welded to the inner surface of the protruding portion of the current collecting member rather than the tip of the resistance welding electrode. Further, even if the resistance welding electrode is removed after resistance welding, the sputtered dust remains attached to the surface of the current collecting member and is very unlikely to peel off.

Therefore, according to the method for manufacturing a rectangular secondary battery of the present invention, it becomes difficult for spatter to occur between the resistance welding electrode and the current collecting member during resistance welding, and even if spatter is generated, Remains in a fused state on the surface of the current collecting member, so that it is less likely to scatter to the outside. Therefore, a highly reliable prismatic secondary battery in which the occurrence of defects in the prismatic secondary battery as a product is suppressed can be obtained. Can be manufactured.

Moreover, in the manufacturing method of the square secondary battery of this invention, the height of the protrusion part provided in the said current collection member as the said current collection member is lower than the height of the convex part provided in the said intermediate conductive member It is preferable to use one.

In resistance welding, if the contact area between the members to be welded increases, the energization path increases accordingly, and heat generation cannot be obtained sufficiently. When the relationship between the height of the protruding portion provided on the current collecting member and the height of the convex portion of the intermediate conductive member changes, the convex portion of the intermediate conductive member and the core exposed portion when the pressure is applied with the resistance welding electrode And the contact area of the protrusion part provided in the current collection member changes. The contact area increases as the height of the protrusion provided on the current collecting member increases, and decreases as the height of the protrusion provided on the current collecting member decreases. On the other hand, in the state after being pressurized with the resistance welding electrode, if the height of the protruding portion provided on the current collecting member is high, the base portion of the laminated core exposed portion and the convex portion of the intermediate conductive member, that is, Since the main body of the intermediate conductive member is in contact with and strongly pressed, heat is dissipated quickly in this part and heat generation is difficult. However, if the height of the protruding portion provided on the current collecting member is low, the laminated core body And the base part of the convex part of the intermediate conductive member is difficult to contact, or even if it is in contact, it is not strongly crimped, so it is difficult to dissipate heat at this part, so heat is easily generated, and resistance welding can be performed in a more stable state . According to the method for manufacturing a rectangular secondary battery of the present invention, since the height of the protrusion provided on the current collecting member is lower than the height of the protrusion provided on the intermediate conductive member, the resistance Since the area of the energization path in the state after being pressurized with the welding electrode can be reduced, resistance welding can be performed in a more stable state.

In the method for manufacturing a rectangular secondary battery of the present invention, the current collecting member is such that the height of the protruding portion provided on the current collecting member does not exceed the thickness of the current collecting member. It is preferable.

If the current collector has a height of the protruding portion provided on the current collector that does not exceed the thickness of the current collector, the current collector is nearly flat, so it is divided into two parts. Since the contact state with the exposed core is improved, the quality of the resistance welding portion is improved and the efficiency during resistance welding is improved.

In the method for manufacturing a rectangular secondary battery of the present invention, as the current collecting member, the diameter of the top of the protruding portion provided on the current collecting member is 1.5 times the diameter of the convex portion of the intermediate conductive member. It is preferable to use the above.

As the current collecting member, when the diameter of the top portion of the protruding portion provided on the current collecting member is 1.5 times or more the diameter of the convex portion of the intermediate conductive member, the current collecting member is pressed by the resistance welding electrode. Since the center shift at the time of positioning can be absorbed when the projecting portion is deformed, the above-described effect of the present invention is favorably achieved. Further, the upper limit is not critical, but if it is too large, the size of the current collecting member itself increases, so it is preferable that W1 / W2 ≦ 3.0.

In the method for manufacturing a rectangular secondary battery according to the present invention, the current collecting member includes a dent on the top of the protruding portion provided on the current collecting member that faces away from the intermediate conductive member side. It is preferable to use what is.

If the top of the protruding part provided on the current collecting member is provided with a dent facing away from the intermediate conductive member side, the back side of the dent of the protruding part formed on the current collecting member during resistance welding Since the portion corresponding to the convex portion of the intermediate conductive member enters, the positioning between the current collecting member and the intermediate conductive member is facilitated, and resistance welding can be performed in a more stable state.

Further, in the method for manufacturing a rectangular secondary battery of the present invention, in the step of performing resistance welding while pressing with the pair of resistance welding electrodes, the protrusion formed on the current collecting member and the body of the intermediate conductive member The total thickness of the stacked core exposed portions existing between the projecting portion formed on the current collecting member and the intermediate conductive member (the thickness of one core × the number of stacked layers) It is preferable to flow a resistance welding current in a larger state.

According to the method for manufacturing a rectangular secondary battery of the present invention, in the vicinity of the resistance welded portion, a portion other than the protruding portion provided on the current collecting member, the core exposed portion and the convex portion of the intermediate conductive member, that is, the main body portion. Since there is a gap between them, the projecting portion provided on the current collecting member, the core exposed portion, and the main body portion of the intermediate conductive member do not adhere to each other, and heat dissipation to the main body portion of the intermediate conductive member occurs at this portion. It is difficult and the resistance welding part tends to generate heat intensively.

Also, in the method for manufacturing a rectangular secondary battery of the present invention, a plurality of intermediate conductive members fixed to an insulating member can be used.

If a thing of such composition is used, since a plurality of middle conductive members are stably fixed to an insulating member, while being easy to insert a plurality of middle conductive members between the core exposure parts divided into two, Since the positioning can be performed stably, the quality of the resistance welded portion is improved. In addition, as an insulating member, if all the convex parts of at least a plurality of intermediate conductive members are exposed, even if the length of the intermediate conductive member has the same width, it is narrower than that. In addition, a prismatic shape, a chamfered prismatic shape, or those in which grooves and gaps are formed to facilitate holding by a holding jig can be used.

1A is a cross-sectional view of the nonaqueous electrolyte secondary battery of Embodiment 1, FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A, and FIG. 1C is taken along an IC-IC line in FIG. 1A. It is sectional drawing. 2A is a plan view of the positive electrode intermediate conductive member of Embodiment 1, FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A, and FIG. 2C is a front view. FIG. 3 is a side view showing a welding state of the first embodiment. 4A is a plan view of the resistance welding electrode, FIG. 4B is a bottom view of the resistance welding electrode, FIG. 4C is a perspective view of a protruding portion formed on the current collecting member, and FIG. 4D is a pair of resistances. FIG. 4E is an enlarged cross-sectional view showing the arrangement of each part before pressing the welding electrode, and FIG. 4E is an enlarged cross-sectional view showing the arrangement of each part after pressing the resistance welding electrode. 5A is an enlarged cross-sectional view for explaining a current path at the time of resistance welding according to the first embodiment, FIG. 5B is an enlarged cross-sectional view illustrating a spatter generation state at the time of resistance welding according to the first embodiment, and FIG. FIG. 5D is an enlarged cross-sectional view for explaining a current path at the time of resistance welding in the comparative example, FIG. 5D is an enlarged cross-sectional view showing a spatter generation state at the time of resistance welding in the comparative example, and FIG. It is an expanded sectional view which shows the generation | occurrence | production state of a sputter | spatter. 6A and 6B are cross-sectional views of a current collecting member according to a modification. FIG. 3 is a cross-sectional view corresponding to FIG. 1B in the prismatic secondary battery of Embodiment 2. 8A is a cross-sectional view of an electric double layer capacitor as a conventional power storage element, FIG. 8B is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A, and FIG. 8C is a cross-sectional view taken along line VIIIC-VIIIC in FIG. FIG. It is a figure which shows the welding process between the core exposed part of an electrode in FIG. 8, and a current collection member. It is a figure explaining the conventional series spot welding method. It is a figure explaining the series spot welding method of another prior art example.

Hereinafter, a mode for carrying out the present invention will be exemplified and described in detail. However, each embodiment shown below is illustrated in order to understand the technical idea of the present invention, and is not intended to specify the present invention to these embodiments. The present invention can be equally applied to various modifications without departing from the technical idea shown in the above-mentioned range. The electrode body for a rectangular secondary battery that can be used in the present invention was produced by winding or laminating a sheet-like positive electrode plate and a negative electrode plate in a state of being insulated from each other via a separator. In the following, a flat electrode body in which a plurality of positive electrode core exposed portions and negative electrode core exposed portions are laminated on both ends will be described as a representative of a wound electrode body.

[Embodiment 1]
First, as an example of the prismatic secondary battery according to the first embodiment of the present invention, a prismatic nonaqueous electrolyte secondary battery will be described with reference to FIG. 1A is a cross-sectional view of the prismatic nonaqueous electrolyte secondary battery of Embodiment 1, FIG. 1B is a cross-sectional view taken along line IB-IB of FIG. 1A, and FIG. 1C is an IC-IC line of FIG. 1A. FIG. This square nonaqueous electrolyte secondary battery 10 has a flat wound electrode body 11 in which a sheet-like positive electrode plate and a negative electrode plate are wound via a separator (both not shown). .

The sheet-like positive electrode plate is coated with a positive electrode active material mixture so that a positive electrode core exposed portion 14 in which a strip-shaped aluminum foil is exposed is formed on both surfaces of a positive electrode core made of aluminum foil, and dried. It is produced by rolling later. The sheet-like negative electrode plate is coated with a negative electrode active material mixture so that the negative electrode core exposed portion 15 where the strip-shaped copper foil is exposed is formed on both surfaces of the negative electrode core made of copper foil. It is made by rolling after drying. The flat wound electrode body 11 includes a sheet-like positive electrode plate and negative electrode plate, and a plurality of positive electrode core exposed portions 14 and negative electrode core exposed portions 15 at both ends in the winding axis direction. For example, it is manufactured by winding in a flat shape through a microporous separator made of polyethylene so as to be exposed.

The plurality of positive electrode core exposed portions 14 are laminated and connected to the positive electrode terminal 17 via the positive electrode current collecting member 16, and the plurality of negative electrode core exposed portions 15 are similarly laminated to form the negative electrode current collecting member 18. To the negative electrode terminal 19. The positive electrode terminal 17 and the negative electrode terminal 19 are fixed to the sealing plate 13 via insulating

members

20 and 21, respectively. Here, a pressure-sensitive current interrupting mechanism or the like may be interposed between the positive electrode current collecting member 16 and the positive electrode terminal 17 or between the negative electrode current collecting member 18 and the negative electrode terminal 19. In the rectangular nonaqueous electrolyte secondary battery 10 according to the first embodiment, the flat wound electrode body 11 manufactured as described above is inserted into the rectangular battery outer can 12, and then the sealing plate 13 is replaced with the battery. Laser welding is performed on the opening of the outer can 12, and then a non-aqueous electrolyte is injected from the electrolyte injection hole 22, and the electrolyte injection hole 22 is sealed.

On the side of the positive electrode plate, the flat wound electrode body 11 has a plurality of stacked positive electrode core exposed portions 14 divided into two parts, and an intermediate conductive member 24 for the positive electrode is sandwiched between them. On the plate side, the plurality of stacked negative electrode core exposed portions 15 are divided into two, and the negative electrode intermediate conductive member 25 is sandwiched therebetween. Also, positive current collecting members 16 are disposed on the outermost surfaces on both sides of the positive electrode core exposed portion 14 located on both sides of the positive electrode intermediate conductive member 24, and on both sides of the negative electrode intermediate conductive member 25. Negative electrode current collecting members 18 are respectively disposed on the outermost surfaces of the negative electrode core body exposed portion 15 located on both sides. The positive electrode intermediate conductive member 24 is made of aluminum, which is the same material as the positive electrode core, and the negative electrode intermediate conductive member 25 is made of copper, which is the same material as the negative electrode core, but the positive electrode intermediate conductive member 24 and the negative electrode The intermediate conductive member 25 for use may have substantially the same shape.

The positive electrode current collector 16 and the positive electrode core exposed portion 14 and the positive electrode core exposed portion 14 and the positive electrode intermediate conductive member 24 are both resistance welded, and the negative electrode current collector The negative electrode core exposed portion 15 and the negative electrode core exposed portion 15 and the negative electrode intermediate conductive member 25 are both connected by resistance welding.

Hereinafter, the shape of the positive electrode intermediate conductive member 24 and the negative electrode intermediate conductive member 25, the positive electrode core exposed portion 14, the positive electrode current collecting member 16, the resistance welding method between the positive electrode intermediate conductive member 24, and the negative electrode core exposed A resistance welding method among the portion 15, the negative electrode current collecting member 18, and the negative electrode intermediate conductive member 25 will be described in detail with reference to FIGS. However, in the first embodiment, the shape of the positive electrode intermediate conductive member 24 and the negative electrode intermediate conductive member 25 is substantially the same, and the positive electrode core exposed portion 14, the positive electrode current collecting member 16, and the positive electrode intermediate member. The resistance welding method between the conductive members 24 and the negative electrode core exposed portion 15, the negative electrode current collecting member 18, and the negative electrode intermediate conductive member 25 may be the resistance welding method between the positive electrode plate side and the negative electrode plate side. However, since it is the same, the following description will be made on the positive electrode plate side as a representative.

The positive electrode intermediate conductive member 24 of Embodiment 1 will be described with reference to FIG. 2A is a plan view of the positive electrode intermediate conductive member 24, FIG. 2B is a cross-sectional view taken along the line IIB-IIB in FIG. 2A, and FIG. 2C is a front view. In the positive electrode intermediate conductive member 24, for example, a truncated cone-shaped convex portion 24b is formed on each of two opposing surfaces of the cylindrical main body portion 24a. The height of the frustoconical convex portion 24b may be about the same as a projection (projection) generally formed on the resistance welding member, that is, about several mm. The convex portion 24b is not limited to a truncated cone shape, and a polygonal frustum shape such as a triangular frustum shape or a quadrangular frustum shape, or a hemispherical shape can also be used.

Further, the diameter and length of the cylindrical main body 24a vary depending on the flat wound electrode body 11 and the battery outer can 12 (see FIG. 1), but may be about 3 mm to several tens of mm. Here, the shape of the body portion 24a of the intermediate conductive member 24 for the positive electrode has been described as a cylindrical shape, but any shape can be used as long as it is a metal block shape such as a prismatic shape or an elliptical columnar shape. can do. Further, as a material for forming the positive electrode intermediate conductive member 24, a material made of copper, copper alloy, aluminum, aluminum alloy, tungsten, molybdenum, or the like can be used. An intermediate conductive member 24 for a positive electrode made of copper, copper alloy, aluminum or aluminum alloy is obtained by changing the portion 24b with nickel plating, changing the convex portion 24b and the vicinity thereof to a metal material that promotes heat generation such as tungsten or molybdenum. What is joined to the main body portion 24a by brazing or the like can also be used.

Next, a specific method for manufacturing the nonaqueous electrolyte secondary battery 10 of Embodiment 1 will be described. As shown in FIG. 3, a positive electrode core exposed portion 14 made of an aluminum foil of a flat wound electrode body 11 is laminated, and the laminated positive electrode core exposed portion 14 is divided into two on both sides from the winding center portion. Then, the positive electrode core exposed portion 14 was concentrated around a quarter of the electrode body thickness. Then, the positive electrode current collecting member 16 is provided on both sides of the outermost peripheral side of the positive electrode core exposed portion 14, the positive electrode intermediate conductive member 24 is provided on the inner peripheral side, and the truncated cone-shaped convex portions 24 b on both sides of the positive electrode intermediate conductive member 24. Are arranged so as to be in contact with the positive electrode core exposed portion 14 respectively. Here, the thickness of the collected aluminum foil is about 660 μm on one side, and the total number of laminated layers is 88 (44 on one side). Further, the positive electrode current collecting member 16 was manufactured by punching an aluminum plate having a thickness of 0.8 mm and bending it. The positive electrode current collecting member 16 may be manufactured from an aluminum plate by casting or the like.

Next, as shown in FIG. 3, the flat wound electrode body 11 in which the positive electrode current collecting member 16 and the positive electrode intermediate conductive member 24 are arranged between a pair of resistance welding electrodes 31 arranged vertically is provided. The pair of resistance welding electrodes 31 are respectively brought into contact with the positive electrode current collecting members 16 arranged on both sides of the outermost peripheral side of the positive electrode core exposed portion 14. Then, a pressing force is applied between the pair of resistance welding electrodes 31 at an appropriate pressure, and resistance welding is performed under a predetermined condition.

A specific configuration of the pair of resistance welding electrodes 31 and the positive electrode current collecting member 16 used in the resistance welding, a change in shape before and after the pressing force is applied to the resistance welding electrode, and the like will be described with reference to FIG. 4A is a plan view of the resistance welding electrode, FIG. 4B is a bottom view of the resistance welding electrode, FIG. 4C is a perspective view of a protruding portion formed on the current collecting member, and FIG. FIG. 4E is an enlarged cross-sectional view showing the arrangement of each part before pressing the resistance welding electrode, and FIG. 4E is an enlarged cross-sectional view showing the arrangement of each part after pressing the resistance welding electrode.

The resistance welding electrode 31 is made of, for example, copper, and as shown in FIGS. 4A and 4B, a cylindrical main body 31a and a truncated conical tip that is tapered on the resistance welding surface side of the main body 31a. The end surface of the truncated cone-shaped tip 31b is a resistance welding surface 31c. Further, as the positive electrode current collecting member 16, a member having a protruding portion 16a protruding toward the intermediate conductive member 24 side is used. The diameter W of the resistance welding surface 31c of the resistance welding electrode 31 is larger than the diameter W1 of the protruding portion 16a of the positive electrode current collecting member 16, as shown in FIG. 4D. Further, the diameter W1 of the protruding portion 16a of the positive electrode current collecting member 16 is larger than the diameter W2 of the convex portion 24b of the positive electrode intermediate conductive member 24. In this example, the protrusion 16a of the positive electrode current collecting member 16 is a protrusion having a flat top. However, the protrusion has a curved or convex shape. May be.

Between the two divided positive electrode core exposed portions 14, the convex portions 24 b on both sides of the positive electrode intermediate conductive member 24 are arranged so as to be in contact with the two divided positive electrode core exposed portions 14. It arrange | positions so that the top part of the protrusion part 16a of the current collection member 16 for positive electrodes may contact | connect the outermost surface of the positive electrode core exposure part 14 of the other side. Further, a pair of resistance welding electrodes 31 are arranged on the outermost surface side of the positive electrode current collecting member 16 on both sides.

At this time, the resistance welding surface 31c of the resistance welding electrode 31 is disposed so as to close the gap 16b based on the protruding portion 16a of the positive electrode current collecting member 16, the resistance welding electrode 31 on one side in this state, and the positive electrode The arrangement relationship among the current collecting member 16, the two-divided positive electrode core exposed portion 14, and the positive electrode intermediate conductive member 24 is shown in FIG. 4D. As apparent from the description of FIG. 4D, a sealed gap 16 b is formed between the protruding portion 16 a of the positive electrode current collecting member 16 and the resistance welding surface 31 c of the resistance welding electrode 31.

Thereafter, when a pressing force is applied so that the pair of resistance welding electrodes 31 face each other, the top of the protruding portion 16a of the positive electrode current collecting member 16 sandwiches the positive electrode core exposed portion 14 divided into two, and the positive electrode The convex portion 24 b of the intermediate conductive member 24 for use is opposed. Therefore, when the pair of resistance welding electrodes 31 are pressed so as to face each other, the top part of the protruding part 16a of the positive electrode current collecting member 16 and the positive electrode core divided into two by the convex part 24b of the positive electrode intermediate conductive member 24 Both exposed portions 14 are deformed toward the resistance welding surface 16 c at the tip of the resistance welding electrode 31, and finally the inner surface of the projecting portion 16 a of the deformed positive electrode current collecting member 16 is the resistance welding surface of the resistance welding electrode 31. Contact 31c. Therefore, the gap 16b between the protruding portion 16a of the positive electrode current collecting member 16 and the resistance welding surface 31c of the resistance welding electrode 31 is formed on the protruding portion 16a of the positive electrode current collecting member 16 as shown in FIG. 4E. It remains in a sealed state on the outer peripheral wall side, and its volume is reduced.

As shown in FIG. 3, when a resistance welding current is applied while applying a pressing force between the pair of resistance welding electrodes 31 at an appropriate pressure, the protruding portion 16a of the positive electrode current collecting member 16 and the positive electrode Since both the convex portions 24b of the intermediate conductive member 24 act as projections, the protruding portion 16a of the positive current collecting member 16 and the two-divided positive electrode core exposed portion 14 disposed between both heat well. Therefore, a large nugget is formed. Therefore, the welding strength between the positive electrode current collecting member 16 and the divided positive electrode core exposed portion 14 and between the divided positive electrode core exposed portion 14 and the positive intermediate conductive member 24 is very strong. Become.

At this time, if the positive electrode current collecting member 16 is used such that the height H of the protrusion 16a formed on the positive electrode current collecting member 16 does not exceed the thickness of the positive electrode current collecting member 16, the positive electrode current collecting member 16 is used. Since the electric member 16 is nearly flat, the contact state between the positive electrode current collecting member 16 and the positive electrode core exposed portion 14 divided into two parts becomes good. Further, when the positive electrode current collecting member 16 is used, the height H of the protruding portion 16a formed on the positive electrode current collecting member 16 is lower than the height of the convex portion 24b provided on the positive electrode intermediate conductive member 24. The contact state between the positive electrode current collector 16 and the positive electrode core exposed part 14 divided into two parts and between the divided positive electrode core exposed part 14 and the positive electrode current collector member 16 becomes good. , It becomes difficult for spatter to occur.

Moreover, since the positive electrode current collecting member 16 has a smaller heat capacity than the resistance welding electrode 31, the surface of the positive electrode current collecting member 16 becomes hot during resistance welding, and the protruding portion 16 a of the positive electrode current collecting member 16. The gap 16b formed between the resistance welding electrode 31 and the resistance welding surface 31c is in a hermetically sealed state, so that the sputtered dust is less likely to jump out to the outside. It welds to the inner surface of the protrusion part 16a of the current collection member 16 for positive electrodes rather than the resistance welding surface 31c. Note that the sputtered dust remains on the surface of the positive electrode current collecting member 16 even after the resistance welding electrode 31 is removed after resistance welding, so that it is very unlikely to peel off.

As shown in FIG. 4D, when resistance welding is performed while pressing with a pair of resistance welding electrodes 31, the protrusions 16a formed on the positive electrode current collecting member 16 and the protrusions of the positive electrode intermediate conductive member 24 are formed. Stacked positive electrode cores that exist between the projecting portion 16a formed on the positive electrode current collecting member 16 and the positive electrode intermediate conductive member 24 at a distance L between the portion other than the portion 24b, that is, the main body portion 24a. It is preferable to flow the resistance welding current in a state where it is larger than the total thickness of the exposed portion 14 (thickness of one core body × number of stacked layers) L2. With such an arrangement relationship, in the vicinity of the resistance welded portion, a portion other than the protruding portion 16a formed on the positive electrode current collecting member 16, the positive electrode core exposed portion 14 and the protruding portion 24b of the positive electrode intermediate conductive member 24, That is, since there is a gap between each of the main body portions 24a, the main body of the protruding portion 16a formed on the BR> A positive electrode current collecting member 16, the positive electrode core exposed portion 14, and the positive electrode intermediate conductive member 24 Since the portion 24a is not in close contact, heat radiation to the main body portion 24a of the intermediate conductive member 24 for the positive electrode hardly occurs at this portion, and the resistance welding portion easily generates heat intensively.

Here, the state of occurrence of spatter during resistance welding in the first embodiment and the comparative example will be described with reference to FIG. 5A is an enlarged cross-sectional view for explaining a current path at the time of resistance welding according to the first embodiment, and FIG. 5B is an enlarged cross-sectional view showing a spatter generation state at the time of resistance welding according to the first embodiment. 5C is an enlarged cross-sectional view for explaining a current path at the time of resistance welding in the comparative example, FIG. 5D is an enlarged cross-sectional view showing a spatter generation state at the time of resistance welding in the comparative example, and FIG. 5E is another comparison. It is an expanded sectional view which shows the generation | occurrence | production state of an example spatter.

As shown in FIG. 5A, the current path at the time of resistance welding according to the first embodiment is such that when a pressing force is applied between the pair of resistance welding electrodes 31 at an appropriate pressure, the protruding portion of the positive electrode current collecting member 16 The bottom surface of 16a contacts the resistance welding surface 31c of the resistance welding electrode 31, and at the same time, between the resistance welding surface 31c of the resistance welding electrode 31 and the outer peripheral wall side of the protruding portion 16a of the positive electrode current collecting member 16 The air gap 16b is formed in a sealed state. When a resistance welding current is passed in this state, as shown in FIG. 5A, the current path is concentrated at the center of the resistance welding electrode 31, so that the heat generation state of the positive electrode current collecting member 16 becomes very good. Sputtering is less likely to occur than in the comparative example shown in FIGS. 5C and 5D, and even if spattering occurs, this spattering is caused by the protruding portion of the positive current collecting member 16 as shown in FIG. 5B. It comes to stop in the space | gap 16b in the sealing state formed in the outer peripheral wall side of 16a, and it becomes difficult to jump out outside this space | gap 16b.

On the other hand, in the case of the comparative example shown in FIG. 5C and FIG. 5D, since the protruding portion 16 a is not formed on the positive electrode current collecting member 16, the current path is the entire resistance welding surface 31 c of the resistance welding electrode 16. Therefore, the degree of heat generation is inferior to that in the first embodiment described above. In addition, when spatter occurs, as shown in FIG. 5D, the sputtered dust pops out to the outside, which is likely to cause inconvenience in the manufactured square secondary battery. As shown in FIG. 5E, the shape of the protruding portion 16a of the positive electrode current collecting member 16 is hemispherical, and a portion of the protruding portion 16a is not in contact with the resistance welding surface 31c of the resistance welding electrode 16 but is in resistance. When welding is performed, sputtering easily occurs between the protruding portion 16a and the positive electrode core exposed portion 14. Further, when the shape of the protruding portion 16a is a hemispherical shape, a displacement is likely to occur when a pressing force is applied to the pair of resistance welding electrodes 31, and a part of the protruding portion 16a is resistance-welded to the resistance welding electrode 16. Since it is difficult to be deformed into a state in contact with the surface 31c, the shape of the protrusion is preferably a shape having a flat top as shown in FIG. 4D or a shape having a slightly flat substantially top.

In addition, in the said Embodiment 1, the example using the thing provided with the column-shaped main-body part 31a and the truncated cone-shaped front-end | tip part 31b was shown as the electrode 31 for resistance welding. However, a polygonal columnar shape can be used as the main body portion 31a of the resistance welding electrode 31, and a polygonal frustum shape can also be used as the tip portion 31b. Moreover, in the said Embodiment 1, the example using the thing by which the truncated cone-shaped convex part 24b was formed in the both end surfaces of the column-shaped main-body part 24a was shown as the intermediate conductive member 24 for positive electrodes. However, in the present invention, the main body portion 24a and the convex portion 24b can be in the shape of a truncated pyramid, that is, a triangular truncated cone shape, a quadrangular truncated cone shape, or a polygonal truncated pyramid shape. .

In the first embodiment, when resistance welding is performed while being pressed by the pair of resistance welding electrodes 31, the protruding portion 16 a formed on the positive electrode current collecting member 16 and the main body portion 24 a of the positive electrode intermediate conductive member 24. Is greater than the total thickness L2 of the stacked positive electrode core exposed portions 14 existing between the protruding portion 16a formed on the positive electrode current collecting member 16 and the intermediate conductive member 24 for positive electrode. An example in which resistance welding was performed in a state was shown. This is because the positive electrode current collector member 16 is such that the height of the protruding portion 16a formed on the positive electrode current collector member 16 is lower than the height of the convex portion 24b provided on the positive electrode intermediate conductive member 24. It shows that

That is, in resistance welding, if the contact area between the members to be welded increases, the energization path increases accordingly, and sufficient heat generation cannot be obtained. However, the height of the protrusion 16a formed on the positive electrode current collecting member 16 is increased. When the relationship between H and the height of the convex portion 24b of the positive intermediate conductive member 24 changes, when the pressure is applied by the pair of resistance welding electrodes 31, the convex portion 24b of the positive intermediate conductive member 24, the positive electrode core The contact area of the protrusion 16a formed on the exposed portion 14 and the positive electrode current collector 16 changes. This contact area increases when the height H of the protrusion 16a formed on the positive current collector 16 is high, and decreases when the height H of the protrusion 16a formed on the positive current collector 16 is low. Become. *

On the other hand, as shown in FIG. 4E, in a state after being pressurized with the pair of resistance welding electrodes 31, when the height H of the protruding portion 16a formed on the positive electrode current collecting member 16 is high, the layers are stacked. Since the core exposed portion 14 for the positive electrode and the base portion of the convex portion 24b of the intermediate conductive member 24 for the positive electrode, that is, the main body portion 24a of the intermediate conductive member 24 for the positive electrode are in contact and strongly pressed, heat dissipation at this portion is quick. It becomes difficult to generate heat. On the other hand, if the height of the protruding portion 16a formed on the positive electrode current collecting member 16 is low, the stacked positive electrode core exposed portion 14 and the main body portion 24a of the positive electrode intermediate conductive member 24 are difficult to contact, Alternatively, even if it is in contact, it is not strongly pressure-bonded, so it is difficult to radiate heat at this portion, so heat is easily generated, and resistance welding can be performed in a stable state.

In addition, the diameter W1 of the top part of the protrusion part 16a formed in the positive electrode current collection member 16 as the positive electrode current collection member 16 and the diameter W2 of the convex part 24b of the positive electrode intermediate conductive member 24 (both refer to FIG. 4D). If a relationship of W1 / W2 ≧ 1.5 is used, the center misalignment at the time of positioning can be absorbed when the protruding portion 24a of the positive electrode current collecting member 24 is deformed by pressing by the pair of resistance welding electrodes 31. As a result, the quality of the resistance weld is stabilized. Further, the upper limit of W1 / W2 is not critical, but if it is too large, the size of the current collecting member itself is also increased, so W1 / W2 ≦ 3.0 is preferable.

In the first embodiment, the case where the plurality of stacked positive electrode core exposed portions 14 are divided into two parts and resistance welding is performed using the positive electrode current collecting member 16 and the positive electrode intermediate conductive member 24 is described. The intermediate conductive member for positive electrode 24 may be used as the current collecting member 16 for positive electrode, and the intermediate conductive member for positive electrode 24 may be connected to the positive electrode terminal 17. In this case, instead of the positive electrode current collecting member used in the first embodiment, a weld receiving member made of a thin plate formed of the same material as the positive electrode intermediate conductive member 24 may be used.

[Modification]
As shown in FIG. 4C, the positive electrode current collecting member 16 of the first embodiment is an example in which the surface is formed with a flat protrusion 16a. FIG. 6A and FIG. As shown in FIG. 6, a recess 16c may be formed on the bottom of the protrusion 16a at a position facing the protrusion 31c of the resistance welding electrode 31. When the one having such a recess 16c is used, it corresponds to the protrusion 24b of the intermediate conductive member 24 for positive electrode on the back side of the recess 16c of the protrusion 16a formed on the current collector 16 for positive electrode during resistance welding. Therefore, the positioning between the positive electrode current collecting member 16 and the positive electrode intermediate conductive member 24 is facilitated.

[Embodiment 2]
In the first embodiment, the example in which only one intermediate conductive member 24 for positive electrode is used is shown, but a plurality of intermediate conductive members for positive electrode can be used. An example of the prismatic secondary battery of Embodiment 2 using a plurality of such positive electrode intermediate conductive members 24 will be described with reference to FIG. FIG. 7 is a cross-sectional view corresponding to FIG. 1B in the prismatic secondary battery according to the second embodiment.

The positive electrode intermediate conductive member 24 used in Embodiment 2 is the same as the positive electrode intermediate conductive member 24 of Embodiment 1, but is fixed to an insulating member 27 made of, for example, a heat-resistant resin material. When such an insulating member 27 having two positive intermediate conductive members 24 fixed thereto is used, the two positive intermediate conductive members 24 are stably fixed to the insulating member 27. Since the positive electrode intermediate conductive member 24 can be easily inserted between the two divided positive electrode core exposed portions 14 and can be stably positioned, the quality of the resistance welded portion is improved.

As the insulating member 27, as long as all the protrusions of the at least two positive electrode intermediate conductive members 24 are exposed, the positive electrode intermediate conductive member 24 may have the same width. Narrower widths may be used, and prismatic and chamfered prismatic shapes, and those formed with grooves and gaps for easy holding by a holding jig may be used. it can. The number of the positive electrode intermediate conductive members 24 may be three or more according to the capacity of the rectangular secondary battery.

DESCRIPTION OF SYMBOLS 10 ... Non-aqueous electrolyte secondary battery 11 ... Flat wound electrode body 12 ... Battery outer can 13 ... Sealing plate 14 ... Positive electrode core exposed part 15 ... Negative electrode core exposed part 16 ... Positive electrode current collecting member 16a ... ( Protruding portion 16b of the positive electrode current collecting member 16b ... Cavity 16c ... Depression (of the current collecting member for positive electrode) 17 ... Positive terminal 18 ... Current collecting member 19 for negative electrode 19 ...

Negative terminal

20, 21 ... Insulating member 22 ... Electrolyte injection Hole 24 ... Intermediate conductive member for positive electrode 24a ... Main body portion (for intermediate conductive member for positive electrode) 24b ... Convex portion for intermediate conductive member for positive electrode 25 ... Intermediate conductive member for negative electrode 27 ... Insulating member 31 ... Electrode for resistance welding 31a ... Cylindrical body part 31b ... Cylindrical tip part 31c ... Resistance welding surface

Claims

A method for manufacturing a prismatic secondary battery having a current collecting structure in which a current collecting member corresponding to each of a stacked positive electrode core exposed portion and a negative electrode core exposed portion of a stacked or wound electrode body is connected,
The step of dividing at least one of the laminated positive electrode core exposed portion and negative electrode core exposed portion into two, the side in contact with the two divided core exposed portions between the core exposed portions on the two divided sides At least one intermediate conductive member having a convex portion formed thereon, and having a diameter larger than the diameter of the convex portion provided on the intermediate conductive member on the outermost surface of the core body exposed portion on the two divided sides Disposing a current collecting member having a protruding portion having a diameter on the intermediate conductive member side so that the protruding portion is opposed to a convex portion provided on the intermediate conductive member via a core exposed portion;
Pressing with a pair of resistance welding electrodes having a resistance welding surface with a diameter larger than the diameter of the protruding portion provided on the current collecting member from both sides of the laminated core exposed portion, a part of the protruding portion is A process of performing resistance welding while being in contact with the resistance welding surface of the electrode for resistance welding,
The manufacturing method of the square secondary battery characterized by having.
The said current collection member uses the thing where the height of the protrusion part provided in the said current collection member is lower than the height of the convex part provided in the said intermediate | middle electrically-conductive member. A method for manufacturing a prismatic secondary battery.
2. The prismatic secondary battery according to claim 1, wherein the current collecting member is a member in which a height of a protrusion provided on the current collecting member does not exceed a thickness of the current collecting member. Manufacturing method.
The said current collection member uses what is equipped with the dent toward the opposite side to the said intermediate | middle electrically-conductive member side in the top part of the protrusion part provided in the said current collection member. Of manufacturing a rectangular secondary battery.
The diameter of the top part of the protrusion part provided in the said current collection member as the said current collection member is 1.5 times or more of the diameter of the convex part of the said intermediate conductive member, The said current collection member is used. Of manufacturing a rectangular secondary battery.
In the step of performing resistance welding while pressing with the pair of resistance welding electrodes, a distance between the protruding portion formed on the current collecting member and the main body portion of the intermediate conductive member is formed on the current collecting member. 2. The rectangular secondary battery according to claim 1, wherein a current for resistance welding is caused to flow in a state where the thickness is larger than the total thickness of the stacked core body exposed portions existing in the protruding portion and the intermediate conductive member. Manufacturing method.
2. The method for manufacturing a rectangular secondary battery according to claim 1, wherein a plurality of intermediate conductive members are fixed to an insulating member.