JP6760111B2 - How to manufacture a secondary battery - Google Patents

Description

The present disclosure relates to a method for manufacturing a secondary battery.

As disclosed in Japanese Patent Application Laid-Open No. 10-340737 (Patent Document 1), in a method for manufacturing a secondary battery, a plurality of predetermined current collecting foil ends (ear portion in Patent Document 1) are collected. A technique is known in which a terminal is inserted inside a slit provided in a bundled state, and both are welded by laser welding. A technique similar to this is also disclosed in JP-A-08-222198 (Patent Document 2), JP-A-08-250103 (Patent Document 3), JP-A-10-106536 (Patent Document 4), and the like. ing.

Japanese Unexamined Patent Publication No. 10-340737 Japanese Unexamined Patent Publication No. 08-222198 Japanese Unexamined Patent Publication No. 08-250103 Japanese Unexamined Patent Publication No. 10-106536

In the conventional method for manufacturing a secondary battery, the ends of a plurality of predetermined current collector foils are inserted into the slits of the current collector terminals in a state of being bundled to some extent. However, it is not easy to properly insert all of the ends of a predetermined number of current collector foils inside the slit. For some of the ends of the current collecting foil, the slit-forming portion of the current collecting terminal prevents entry into the slit, resulting in damage to the current collecting foil or good performance. There is a possibility that a good electrical connection cannot be secured.

An object of the present disclosure is to provide a method for manufacturing a secondary battery, which enables the ends of a plurality of predetermined current collector foils to be easily inserted into slits provided in a current collector terminal.

In the method for manufacturing a secondary battery based on the present disclosure, an electrode main body portion in which current collector foils for a positive electrode and a negative electrode are laminated via a separator, and the current collector foils for a positive electrode and a negative electrode are the electrode main bodies, respectively. A step of forming an electrode body having a current collecting foil extending portion extending on both sides of the portion, and a plurality of the current collecting foils constituting the current collecting foil extending portion. By the step of inserting into the inside of the slit provided in the current collecting terminal and irradiating the laser toward the plurality of current collecting foils arranged inside the slit, the plurality of current collecting foils are said to be described above. Assuming that the process of welding to the current collecting terminal is provided and the dimension in the direction in which the plurality of current collecting foils are inserted into the inside of the slit is defined as the length, the plurality of sheets constituting the current collecting foil extending portion. The current collector foil of the above includes a plurality of first current collector foils and a second current collector foil having a length longer than that of the plurality of first current collector foils, and in the step of forming the electrode body. The second current collecting foil folded back so as to be bent or deformed in the length direction, and a plurality of first current collecting foils sandwiched inside the folded second current collecting foil. In the step of inserting the plurality of current collector foils into the inside of the slit, one insertion portion is formed by the above, and the plurality of the first current collector foils and the second current collector foil are inserted into one. In the state where the portion is formed, the portion of the insertion portion where the second current collecting foil is folded back is inserted into the inside of the slit with the tip in the insertion direction as the tip.

According to the above configuration, the operation of inserting the current collector foil into the slit can be smoothly performed due to the presence of the insertion portion, and further, the current collector foil (second current collector foil) is the required number of current collector foils (second current collector foil). (1) Since the current collector foil) is sandwiched, it is possible to reliably electrically connect the electrode body and the current collector terminal without causing omission of insertion of each current collector foil into the slit.

According to the method for manufacturing a secondary battery having the above configuration, the ends of a plurality of predetermined current collector foils can be easily inserted into the slits provided in the current collector terminals.

It is sectional drawing which shows the secondary battery 10 manufactured by the manufacturing method of the secondary battery in embodiment. It is a perspective view which shows the secondary battery 10 manufactured by the manufacturing method of the secondary battery in embodiment. It is an disassembled assembly drawing which shows the connection structure between an external terminal 36 and a current collector terminal 41. FIG. 5 is an exploded front view showing a positive electrode current collecting foil 21P, a separator 29, and a negative electrode current collecting foil 21N constituting the electrode body 20 (FIGS. 1 and 2). It is a top view which shows the laminated state of the positive electrode current collecting foil 21P, the separator 29, and the negative electrode current collecting foil 21N which make up an electrode body 20. It is sectional drawing which shows the appearance that the insertion part 22Q was formed in the step of forming an electrode body 20 (FIGS. 1 and 2). It is a figure which shows the state at the time of connecting a unit electrode body 20T and a current collector terminal 41. It is a figure which enlarges and shows the region surrounded by VIII line in FIG. It is a perspective view corresponding to FIG. It is a figure which shows the state which the current collector foil is welded to the current collector terminal. It is a figure which shows the state at the time of connecting a unit electrode body and a current collector terminal 41 with respect to a comparative example.

The embodiment will be described below with reference to the drawings. The same parts and equivalent parts may be given the same reference number and duplicate explanations may not be repeated.

1 and 2 are a cross-sectional view and a perspective view showing a secondary battery 10 manufactured by the method for manufacturing a secondary battery according to the embodiment, respectively. The secondary battery 10 is a non-aqueous electrolyte secondary battery, and can be used as, for example, a lithium ion battery. The secondary battery 10 is used, for example, for driving a vehicle, and is used for a hybrid vehicle powered by an internal combustion engine such as a gasoline engine or a diesel engine and a motor powered by a rechargeable battery, or an external charge. It will be installed in plug-in hybrid vehicles, electric vehicles, etc.

(Secondary battery 10)
As shown in FIGS. 1 and 2, the secondary battery 10 includes an electrode body 20, a case body 31, a positive electrode external terminal 36P (FIG. 1), a negative electrode external terminal 36N (FIG. 1), and a positive electrode current collecting terminal 41P. , The negative electrode current collecting terminal 41N is provided. For convenience of illustration, the positive electrode external terminal 36P and the negative electrode external terminal 36N are not shown in FIG. Hereinafter, when the external terminal 36P for the positive electrode and the external terminal 36N for the negative electrode are not particularly distinguished, they are simply referred to as "external terminal 36", and when the current collecting terminal 41P for the positive electrode and the current collecting terminal 41N for the negative electrode are not particularly distinguished, they are simply referred to. It is called "current collector terminal 41".

(Case body 31, external terminal 36, current collecting terminal 41)
The case body 31 has the appearance of the secondary battery 10. The case body 31 is formed of a metal such as aluminum. The case body 31 is configured by combining the main body portion 32 and the lid portion 33. The main body 32 has a bottomed square shape, and the lid 33 is provided so as to close the opening of the main body 32. The positive electrode external terminal 36P (FIG. 1) and the negative electrode external terminal 36N (FIG. 1) are attached to the lid portion 33.

FIG. 3 is an exploded assembly view showing a connection structure between the external terminal 36 and the current collector terminal 41. The external terminal 36 is arranged outside the case body 31 (FIG. 1), and is superposed on the outer surface (upper surface) of the lid portion 33 via the insulator 37. The current collecting terminal 41 is arranged inside the case body 31 and is superposed on the inner surface (lower surface) of the lid portion 33 via the insulator 38. By inserting the conductive pin member 39 from the current collecting terminal 41 to the external terminal 36, the current collecting terminal 41 and the external terminal 36 are electrically connected. The connection structure between the positive electrode external terminal 36P and the positive electrode current collecting terminal 41P and the connection structure between the negative electrode external terminal 36N and the negative electrode current collecting terminal 41N are similarly configured.

The current collecting terminal 41 has a base portion 42 and an arm portion 43 as its constituent parts (see also FIG. 9). The positive electrode current collector terminal 41P is made of aluminum, for example, and has a thickness of 1 mm and a width of 24 mm. The current collecting terminal 41N for the negative electrode is made of copper, for example, and has a thickness of 1 mm and a width of 24 mm. The base portion 42 has a flat plate shape and is superposed on the inner surface of the lid portion 33 via the insulator 38. The arm portion 43 bends from the base portion 42 and extends in a direction away from the base portion 42. A plurality of slits 44 (FIGS. 7 to 9) are formed in the arm portion 43. The slit 44 extends substantially linearly along the direction in which the arm portion 43 extends, and reaches the tip of the arm portion 43. The plurality of slits 44 are arranged at intervals in the thickness direction of the electrode body 20 (direction perpendicular to the paper surface of FIG. 1) (FIGS. 2 and 9). A current collecting terminal 41 can be obtained by forming, for example, four 0.5 mm slits 44 in a metal plate by laser processing or press processing, and then bending the metal plate into an L shape.

(Electrode body 20)
FIG. 4 is an exploded front view showing the positive electrode current collecting foil 21P, the separator 29, and the negative electrode current collecting foil 21N constituting the electrode body 20 (FIGS. 1 and 2). FIG. 5 is a top view showing a state in which the positive electrode current collecting foil 21P, the separator 29, and the negative electrode current collecting foil 21N constituting the electrode body 20 are laminated. The electrode body 20 (FIG. 2) is housed in the case body 31 together with the current collecting terminal 41 and the electrolytic solution (not shown). The electrode body 20 is composed of a laminate of a plurality of positive electrode current collecting foils 21P, a plurality of separators 29, and a plurality of negative electrode current collecting foils 21N.

With reference to FIGS. 4 and 5, the plurality of positive electrode current collector foils 21P are a plurality of positive electrode current collector foils 21P1 (first current collector foil) and a positive electrode current collector foil 21P2 (second current collector foil). And include. The plurality of negative electrode current collector foils 21N include a plurality of negative electrode current collector foils 21N1 (first current collector foil) and a plurality of negative electrode current collector foils 21N2 (second current collector foil). Hereinafter, when the positive electrode current collector foils 21P1, 21P2 are not particularly distinguished, they are collectively referred to simply as "positive electrode current collector foil 21P", and when the negative electrode current collector foils 21N1, 21N2 are not particularly distinguished, these are collectively referred to. Are collectively referred to simply as "current collector foil 21N for negative electrode".

The positive electrode current collecting foil 21P is formed of an aluminum foil having a substantially rectangular shape. A paste 26 containing a positive electrode active material is applied to both surfaces of the positive electrode current collecting foil 21P. On one peripheral edge of the positive electrode current collecting foil 21P extending in the longitudinal direction, a peripheral edge portion 22 to which the paste 26 is not applied is formed so as to extend in a band shape.

The negative electrode current collector foil 21N is formed of a copper foil having substantially the same shape as the positive electrode current collector foil 21P. A paste 27 containing a negative electrode active material is applied to both surfaces of the negative electrode current collecting foil 21N. A peripheral edge portion 23 to which the paste 27 is not applied is formed on one peripheral edge extending in the longitudinal direction of the negative electrode current collecting foil 21N so as to extend in a band shape.

The separator 29 has a substantially rectangular shape and is composed of, for example, a porous polypropylene resin sheet. For example, the positive electrode current collector foil 21P1, the separator 29, the negative electrode current collector foil 21N1, the separator 29, the positive electrode current collector foil 21P2, the separator 29, and the negative electrode current collector foil 21N2 are arranged in the order described.

The region where the paste 26 is applied to the positive electrode current collector foil 21P and the region where the paste 27 is applied to the negative electrode current collector foil 21N face each other via the separator 29. The peripheral edge 22 of the positive electrode current collector foil 21P is exposed from one end extending in the longitudinal direction of the separator 29 (left-right direction in FIG. 4), and the peripheral edge 23 of the negative electrode current collector foil 21N is the separator 29. Is exposed from the other end extending in the longitudinal direction (horizontal direction in the paper surface of FIG. 4).

The electrode body 20 is formed by laminating a plurality of positive electrode current collecting foils 21P, a plurality of separators 29, and a plurality of negative electrode current collecting foils 21N as described above. The electrode body 20 configured in this way (see FIGS. 1 and 2) includes an electrode main body portion 25, a positive electrode current collecting foil extending portion 24P, and a negative electrode current collecting foil extending portion 24N as its constituent parts. Has. Hereinafter, when the positive electrode current collecting foil extending portion 24P and the negative electrode current collecting foil extending portion 24N are not particularly distinguished, they are simply referred to as “current collecting foil extending portion 24”.

The electrode main body 25 is a portion where the positive electrode current collecting foil 21P and the negative electrode current collecting foil 21N are laminated via the separator 29 (FIG. 2). The positive electrode current collecting foil extending portion 24P is a portion where the positive electrode current collecting foil 21P extends from the electrode main body 25 to one side, and the negative electrode current collecting foil extending portion 24N is a negative electrode current collecting foil extending portion 24N. This is a portion where the foil 21N extends from the electrode body 25 to the other side. The electrode body 25 is located between the positive electrode current collector foil extension 24P and the negative electrode current collector foil extension 24N.

In the positive electrode current collecting foil extending portion 24P, a plurality of positive electrode current collecting foils 21P are laminated in the thickness direction of the electrode body 20. The positive electrode current collecting terminal 41P electrically connects the positive electrode external terminal 36P (FIG. 1) and the positive electrode current collecting foil extending portion 24P (a plurality of positive electrode current collecting foils 21P). In the negative electrode current collecting foil extending portion 24N, a plurality of negative electrode current collecting foils 21N are laminated in the thickness direction of the electrode body 20. The negative electrode current collecting terminal 41N electrically connects the negative electrode external terminal 36N (FIG. 1) and the negative electrode current collecting foil extending portion 24N (a plurality of negative electrode current collecting foils 21N).

The positive electrode current collecting terminal 41P is formed of the same type of metal as the metal forming the positive electrode current collecting foil 21P. The negative electrode current collecting terminal 41N is formed of the same type of metal as the metal forming the negative electrode current collecting foil 21N. To exemplify the material, the positive electrode current collector terminal 41P is formed of aluminum which does not corrode even at a high potential and has a characteristic of low resistivity. The negative electrode current collecting terminal 41N is made of copper, which has a small specific resistance and does not alloy with lithium (Li).

Here, when the current collecting terminal 41 and the current collecting foil extending portion 24 are connected, the current collecting foil extending portion 24 is inserted inside the slit 44 provided in the current collecting terminal 41 (FIG. 2). , Fig. 9). At this time, the current collecting terminal 41 is moved relative to the current collecting foil extending portion 24 in the direction indicated by the arrow AR so that the current collecting foil extending portion 24 enters the inside of the slit 44 of the current collecting terminal 41. Be done. The detailed technical significance will be described later, but the direction indicated by the arrow AR is defined here as the “insertion direction”.

With reference to FIG. 4 again, the dimension (dimension in the above insertion direction) in the direction in which a plurality of positive electrode current collector foils 21P (positive electrode current collector foil extension portion 24P) are inserted inside the slit 44 is "length". Is defined. The plurality of positive collector foils 21P constituting the positive electrode current collector foil extending portion 24P include a plurality of positive electrode current collector foils 21P1 (first current collector foil) having a length L1 and a plurality of positive electrodes. It includes a plurality of positive current collector foils 21P2 (second current collector foils) having a length L2 longer than that of the current collector foils 21P1 (a plurality of first current collector foils).

That is, a protruding piece 22U extending in a direction parallel to the insertion direction (arrow AR) is formed on the peripheral edge portion 22 of the positive electrode current collector foil 21P2 (the paste 26 is not coated). .. On the other hand, in the peripheral portion 22 (the paste 26 is not coated) of the positive electrode current collecting foil 21P1, an end portion 22T is formed at a portion corresponding to the protruding piece 22U.

The peripheral portion 22 of the positive electrode current collecting foil 21P1 (which constitutes the positive electrode current collecting foil extending portion 24P) and the positive electrode current collecting foil 21P2 (which constitutes the positive electrode current collecting foil extending portion 24P) are formed. ) Comparing with the peripheral portion 22, the positive electrode current collector foil 21P2 is longer than the positive electrode current collector foil 21P1 by the amount of the protruding piece 22U (length L2-length L1). When the positive electrode current collector foil 21P2 and the positive electrode current collector foil 21P1 are laminated via the separator 29 and the negative electrode current collector foil 21N, the protruding piece 22U protrudes from the end 22T (separator 29) in the insertion direction. Arranged to do. The protruding length of the protruding piece 22U from the separator 29 is, for example, 5 mm.

(Production method)
As shown in FIGS. 5 and 6, in the step of forming the electrode body 20 (FIGS. 1 and 2), the positive electrode current collector foil 21P2 (the positive electrode current collector foil 21P2) is bent or curved in the length direction (insertion direction). The protruding piece 22U of the second current collector foil) is folded back. The end 22T of each of a plurality of positive electrode current collector foils 21P1 (first current collector foil) is sandwiched inside the protruding piece 22U of the folded positive electrode current collector foil 21P2 (second current collector foil). (By being wrapped), one insertion section 22Q (FIG. 6) is formed.

Similarly for the negative electrode side (FIG. 4), the plurality of negative electrode current collector foils 21N constituting the negative electrode current collector foil extending portion 24N are the plurality of negative electrode current collector foils 21N1 (No. 1) having a length L1. (1 current collector foil) and a plurality of negative electrode current collector foils 21N2 (second current collector foil) having a length L2 longer than the plurality of negative electrode current collector foils 21N1 (plurality of the first current collector foils). And include.

A protruding piece 23U extending in a direction parallel to the insertion direction (arrow AR) is formed on the peripheral edge portion 23 of the negative electrode current collector foil 21N2 (the paste 27 is not coated). On the other hand, an end portion 23T is formed at a portion corresponding to the protruding piece 23U on the peripheral edge portion 23 (the paste 27 is not coated) of the negative electrode current collecting foil 21N1. When the negative electrode current collector foil 21N2 and the negative electrode current collector foil 21N1 are laminated via the separator 29 and the positive electrode current collector foil 21P, the protruding piece 23U protrudes from the end 23T (separator 29) in the insertion direction. Arranged to do.

As shown in FIG. 5, in the step of forming the electrode body 20 (FIGS. 1 and 2), the negative electrode current collector foil 21N2 (second collection) is bent or curved in the length direction (insertion direction). The protruding piece 23U of the electric foil) is folded back. The end 23T of each of the plurality of negative electrode current collector foils 21N1 (first current collector foil) is sandwiched inside the protruding piece 23U of the folded negative electrode current collector foil 21N2 (second current collector foil). (By being wrapped), one insertion portion similar to the insertion portion 22Q (FIG. 6) is also formed on the negative electrode side.

The formation of the insertion portion (insertion portion 22Q) as described above is performed for each predetermined stacking unit on both the positive electrode side and the negative electrode side. For example, of the 72 positive electrode current collector foils 21P, four of them have a protruding piece 22U as the positive electrode current collector foil 21P2, and the remaining 68 sheets are used as the positive electrode current collector foil 21P1. The one that does not have the protruding piece 22U is adopted.

In constructing one electrode body 20, a total of 72 positive electrode current collector foils 21P are divided into four, and 17 positive electrode current collector foils 21P1 and one positive electrode current collector foil 21P2 are laminated. , The positive electrode current collector foil 21P2 is arranged at the most extreme position in the stacking direction. Each positive collector foil 21P is made of, for example, aluminum or an aluminum alloy, has a thickness of 15 μm, a lateral dimension (corresponding to a length L1) of 76 mm, and a longitudinal dimension of 130 mm. By forming the paste 26 (active material mixture layer) on both sides while leaving 10 mm corresponding to the peripheral edge portion 22, a total of 72 positive electrode current collector foils 21P can be obtained. For four of them, the length L2 is 80 mm, and the protruding piece 22U is cut out so as to have a length of 5 mm.

The separator 29 has a lateral dimension of 84 mm, a longitudinal dimension of 134 mm, and a thickness of 24 μm. The protruding length of the protruding piece 22U from the separator 29 is, for example, 5 mm. The length of the protruding piece 22U to be bent (the difference in length between the positive electrode current collecting foil 21P2 and the positive electrode current collecting foil 21P1) is "the length of the protruding piece 22U protruding from the separator 29 and the predetermined number of laminated pieces. It is preferable that the value corresponds to "the sum of the total thickness of the positive electrode current collector foil 21P (18 sheets here)".

By bending the protruding piece 22U of the positive electrode current collecting foil 21P2 as described above, one unit electrode body 20T having one insertion portion 22Q is formed. Such one unit electrode body 20T also has one insertion portion on the negative electrode side. Each of the current collector foils 21N for the negative electrode is made of, for example, electrolytic copper foil, has a thickness of 10 μm, a dimension in the lateral direction (corresponding to the length L1) of 76 mm, and a dimension in the longitudinal direction of 134 mm. By forming the paste 27 (active material mixture layer) on both sides while leaving 10 mm corresponding to the peripheral edge portion 23, a total of 72 negative electrode current collector foils 21N can be obtained. For four of them, the length L2 is 84 mm, and the protruding piece 23U is cut out so as to have a length of 5 mm. By bending the protruding piece 23U of the negative electrode current collector foil 21N2 as described above, one unit electrode body 20T having one insertion portion similar to the insertion portion 22Q is formed. A total of four unit electrode bodies 20T having such a configuration are produced.

As shown in FIG. 7, by superimposing the four unit electrode bodies 20T, the electrode body 20 having a state before being connected to the current collecting terminal 41 can be obtained. FIG. 8 is an enlarged view showing a region surrounded by the VIII line in FIG. 7. FIG. 9 is a perspective view corresponding to FIG.

As shown in FIGS. 7 to 9, the positive electrode current collecting terminal 41P is moved relative to the positive electrode current collecting foil extending portion 24P in the direction indicated by the arrow AR (insertion direction). The positive electrode current collecting foil 21P (for a plurality of positive electrodes) with the mountain-shaped portion 22S (FIG. 8) in which the positive electrode current collecting foil 21P2 (protruding piece 22U) of the insertion portion 22Q is folded back as the tip in the insertion direction. The current collector foil 21P1 and the positive electrode current collector foil 21P2) are inserted inside the slit 44 of the positive electrode current collector terminal 41P in a state where one insertion portion 22Q is formed as a whole.

As shown in FIG. 9, the electrode body 20 (four unit electrode bodies 20T) that has been inserted into the positive electrode current collecting terminal 41P is set in a welding jig (not shown). By applying pressure from both sides of the positive electrode current collecting terminal 41P, the slit 44 is tightened so as to sandwich the positive electrode current collecting foil 21P. After that, with the slit 44 tightened, the slit 44 of the positive electrode current collecting foil 21P and the positive electrode current collecting terminal 41P protruding from the positive electrode current collecting terminal 41P is irradiated with a laser (white arrow in FIG. 10). , Weld these. As the welding conditions on the positive electrode side, for example, a fiber laser having an output of 2500 W and a speed of 1800 mm / SEC can be used. As the welding conditions on the negative electrode side, a fiber laser having an output of 1500 W and a speed of 1800 mm / SEC can be used.

The electrode body 20 integrated with the external terminal 36 (FIG. 1) and the like is inserted into the case body 31 (main body portion 32), and the external terminal 36 (lid portion 33) and the main body portion 32 are welded together. The electrode body 20 shown in FIG. 1 can be obtained by injecting the electrolytic solution through the liquid injection hole provided in the lid 33 and then plugging the liquid injection hole.

(Action and effect)
According to the configuration of the embodiment, in a state where a plurality of positive electrode current collecting foils 21P1 and positive electrode current collecting foils 21P2 form one insertion portion 22Q, the positive electrode current collecting foil 21P2 of the insertion portions 22Q is formed. It is inserted inside the slit 44 with the mountain-shaped portion 22S in which the is folded back as the tip in the insertion direction. Therefore, the operation of inserting the positive electrode current collector foil 21P into the slit 44 can be smoothly performed, and further, the protruding pieces 22U of the positive electrode current collector foil 21P2 wrap the required number of positive electrode current collector foils 21P1. Therefore, the positive electrode current collecting foil 21P does not leak into the slit 44, and the electrical connection between the electrode body 20 and the positive electrode current collecting terminal 41P becomes more reliable. This also applies to the negative electrode side.

With reference to FIG. 11, when the configuration of the above embodiment is not adopted, the respective end portions 22T of the predetermined plurality of positive electrode current collector foils 21P are bundled to some extent. Is inserted into the slit 44 of the positive electrode current collecting terminal 41P. However, it is not easy to properly insert all of the end portions 22T of the predetermined plurality of positive electrode current collecting foils 21P into the inside of the slit 44, and some of the plurality of positive electrode current collecting foils 21P. With respect to the end portion 22T of the positive electrode, the portion of the positive electrode current collecting foil 21P forming the slit 44 is prevented from entering the slit 44, and as a result, a part of the positive electrode current collecting foil 21P is damaged. , There is a possibility that good electrical connection cannot be secured.

Generally, the end of the current collecting foil of an alkaline storage battery is made of nickel, has high strength, and has a thickness of 100 μm to 200 μm. In the case of a lithium ion battery, the current collector foil is made of aluminum or copper foil, has a lower strength than nickel, and has an extremely thin thickness of about 10 μm per sheet. The number of stacked batteries is, for example, close to 100 for a large-capacity battery for automobiles, but when the end of the current collector of the electrode body is divided into the required number, the thickness becomes, for example, about 0.5 mm.

Therefore, the slit of the current collector terminal has the dimensions necessary for inserting each end of the plurality of current collector foils, and is configured to be thin enough to enable welding with the end portions of the current collector foils. ing. As a result, each end of the plurality of current collector foils is liable to be bent or damaged when inserted into the slit, and it is difficult for the workplace to avoid these problems. Further, in the case of a laminated electrode body, the current collecting foil that could not be inserted into the slit may not be sufficiently electrically connected, which may lead to the inability to realize an appropriate battery capacity.

According to the configuration of the above-described embodiment for these events, the operation of inserting the current collector foil into the slit can be smoothly performed, and further, the protruding piece of the current collector foil (second current collector foil). Wraps the required number of current collector foils (first current collector foil), so there is no omission of insertion of each current collector foil into the slit, and the electrical connection between the electrode body and the current collector terminal is established. It is possible to do it reliably.

Although the embodiments have been described above, the above disclosure contents are examples in all respects and are not restrictive. The technical scope of the present disclosure is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 secondary battery, 20 electrode body, 20T unit electrode body, 21N, 21N1,21N2 negative electrode current collector foil, 21P1,21P2,21P positive electrode current collector foil, 22,23 peripheral part, 22Q insertion part, 22S part, 22T , 23T end, 22U, 23U projecting piece, 24, 24N, 24P extension, 25 electrode body, 26, 27 paste, 29 separator, 31 case body, 32 body, 33 lid, 36 external terminal, 36N External terminal for negative electrode, 36P External terminal for positive electrode, 37,38 insulator, 39-pin member, 41,41N, 41P Current collector terminal, 42 base, 43 arm, 44 slit, AR arrow, L1, L2 length.

Claims (1)

An electrode main body portion in which current collector foils for a positive electrode and a negative electrode are laminated via a separator, and a collection of current collector foils for a positive electrode and a negative electrode extending on both sides of the electrode main body portion, respectively. A step of forming an electrode body having an electric foil extending portion and
A step of inserting the plurality of current collector foils constituting the current collector foil extending portion into the inside of a slit provided in the current collector terminal, and
A step of welding a plurality of the current collecting foils to the current collecting terminals by irradiating a laser toward the plurality of the current collecting foils arranged inside the slit.
Assuming that the dimension in the direction in which the plurality of current collector foils are inserted into the inside of the slit is defined as the length, the plurality of the current collector foils constituting the current collector foil extending portion are a plurality of first sheets. A current collector foil and a second current collector foil having a length longer than that of the first current collector foil are included.
In the step of forming the electrode body, the second current collector foil folded back so as to be bent or curved in the length direction, and a plurality of sheets sandwiched inside the folded second current collector foil. One insertion portion is formed by the first current collector foil of the above.
In the step of inserting the plurality of current collector foils into the inside of the slit, the insertion in a state where the plurality of the first current collector foils and the second current collector foil form one insertion portion. The portion of the portion where the second current collector foil is folded back is inserted into the inside of the slit with the tip in the insertion direction as the tip.
How to manufacture a secondary battery.

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