JP5949535B2 - Secondary battery manufacturing method and secondary battery - Google Patents

Description

  The present invention relates to a method for manufacturing a secondary battery and a secondary battery, and more particularly to a method for manufacturing a secondary battery and a secondary battery capable of satisfactorily welding a current collector terminal to a current collector laminate.

  In recent years, secondary batteries such as lithium ion secondary batteries have been used in various fields such as electronic devices such as mobile phones and personal computers, vehicles such as hybrid cars and electric cars. In particular, a lithium ion secondary battery has a high energy density and is suitable for mounting in various devices.

  As such a secondary battery, for example, a secondary battery having a configuration in which a wound electrode body wound in a flat shape is accommodated in a rectangular battery case is known. The wound electrode body of the secondary battery has a positive electrode plate having a positive electrode active material layer formed on the surface of a foil-shaped positive electrode current collector, and a negative electrode active material layer formed on the surface of the foil-shaped negative electrode current collector. The negative electrode plate and a separator that insulates the positive electrode plate and the negative electrode plate are stacked and wound. This wound electrode body has a positive electrode current collector laminated portion formed by winding a positive electrode active material layer non-formed portion where a positive electrode active material layer is not formed on one end side along the winding axis direction, and a negative electrode A negative electrode current collector laminated portion formed by winding a negative electrode active material layer non-formed portion where no active material layer is formed is provided on the other end side along the winding axis direction. A positive electrode current collector terminal is joined to the positive electrode current collector laminated portion, and a negative electrode current collector terminal is joined to the negative electrode current collector laminated portion.

  Here, the negative electrode current collector terminal is joined to the negative electrode current collector laminated portion by resistance welding. This is in consideration of productivity and economy. In resistance welding, the negative electrode current collector laminated portion and the negative electrode current collector terminal are overlapped, and the overlapped portion is connected to an electrode on the negative electrode current collector laminated portion side (referred to as “laminated portion side electrode”) and a negative electrode current collector terminal. The electrode is sandwiched between two electrodes (referred to as “terminal electrode”) and pressurized, and a current flows between both electrodes. As a result, Joule heat is generated, the portion sandwiched between both electrodes is melted, and the negative electrode current collector terminal is joined to the negative electrode current collector laminated portion. For resistance welding, a resistance welding machine having a pair of electrodes including a laminated portion side electrode and a terminal side electrode is used.

  As a conventional technique related to resistance welding between such a current collector laminated portion and a current collecting terminal, for example, a technique shown in Patent Document 1 below can be cited. In Patent Document 1 below, the current collector laminated portion (“positive electrode core exposed portion 14” or “negative electrode core exposed portion”) is divided into two parts, and an “energization block 24A” is disposed between them, and the resistance Current collecting terminals (positive current collecting member 16 or negative current collecting member) arranged on the surface of the current collector laminated portion by a pair of electrodes of the welding machine ("resistance welding electrodes 31, 32"), current collector A technique for performing resistance welding by sandwiching a laminated portion and a current-carrying block is disclosed (see FIG. 3 of Patent Document 1 below).

JP 2011-92995 A

  By the way, in the conventionally used lamination-side electrode of the resistance welder, the contact surface with the current collector lamination part has a surface roughness (JIS standard maximum roughness Rmax) of about 1 μm to 10 μm. It was. That is, the contact surface was not so rough. FIG. 11 is a photograph of the contact surface 50 of the conventional laminated portion side electrode.

  For this reason, the biting into the current collector laminated portion of the laminated portion side electrode due to the pressure applied during resistance welding was weak. In detail, it did not bite to such an extent that the unevenness | corrugation of the contact surface 50 (FIG. 11) of the lamination | stacking part side electrode moved into a collector laminated part. Therefore, even if the laminated portion side electrode is pressed, the current collector laminated portion does not extend so much, and the contact area between the laminated portion side electrode and the current laminated portion is small. If welding is performed with a small contact area, the welding strength will be low. FIG. 12 is a photograph of a welding mark 60 formed on the current collector laminated portion by resistance welding. The surface roughness of the weld mark 60 is 4 μm to 8 μm in terms of the maximum roughness Rmax.

  In addition, since the bite was weak and the adhesion of each layer constituting the current collector laminate was low, the contact resistance was high. For this reason, when a large current required for welding the current collector laminated portion is passed, excessive heat generation is caused, which may cause sputtering. Furthermore, the spatter may be scattered on the laminated portion side electrode, which may cause the current collector laminated portion to easily stick to the laminated portion side electrode. As a result, the welded portion of the current collector laminate was damaged, and the welding strength of the current collector laminate could vary. Furthermore, the laminated part side electrode was damaged, and its life could be shortened.

  The present invention has been made in view of the above circumstances. That is, the subject is to provide a method of manufacturing a secondary battery and a secondary battery capable of satisfactorily resistance-welding the current collector stack and the current collector terminal without causing spattering. There is.

The manufacturing method of the secondary battery of the present invention made for the purpose of solving this problem is:
A positive electrode plate with a positive electrode active material layer formed on the surface of a foil-shaped positive electrode current collector and a negative electrode plate with a negative electrode active material layer formed on the surface of a foil-shaped negative electrode current collector are wound together with a separator. Thus, a positive electrode current collector in which a positive electrode active material layer non-formed portion where no positive electrode active material layer is formed is stacked at one end of both ends in the winding axis direction so as to protrude from the negative electrode plate A negative electrode current collector laminated part having a laminated part and laminated in a state where a negative electrode active material layer non-formed part on which the negative electrode active material layer is not formed protrudes from the positive electrode plate at the other end part of both end parts Producing a wound electrode body having:
Disposing a current collector terminal of a corresponding electrode on a current collector laminate of at least one of the positive electrode current collector laminate and the negative electrode current collector laminate; and
The terminal electrode for resistance welding is brought into contact with the current collector terminal arranged in the current collector laminated portion, and the current collector laminated portion in which the current collector terminal is arranged is contacted with the laminated portion side electrode paired with the terminal side electrode. A step of sandwiching the current collector terminal and the current collector laminated portion by contacting,
A process of resistance welding while applying a pressing force between the terminal side electrode and the laminated part side electrode,
The laminated portion side electrode is characterized in that the contact surface with the current collector laminated portion is an uneven surface having a regular uneven shape with a maximum roughness (Rmax) of 15 μm to 25 μm.

The laminated part side electrode used in the method for producing a secondary battery of the present invention has a regular uneven shape with a surface roughness (maximum roughness Rmax, JIS standard) of 15 μm to 25 μm at the contact surface with the current collector laminated part. It is an uneven surface having That is, the contact surface is rougher than before. For this reason, the laminated portion side electrode bites into the current collector laminated portion due to pressurization during resistance welding. The degree of this biting is such that the unevenness of the contact surface of the laminated portion side electrode moves into the current collector laminated portion. Note that the degree of unevenness transferred to the current collector laminate is about 9 μm to 25 μm in terms of the maximum roughness Rmax. Thus, since the laminated part side electrode bites into the current collector laminated part, the current collector laminated part is stretched (stretched). Therefore, the contact area between the laminated portion side electrode and the current collector laminated portion increases. Therefore, the welding strength between the current collector laminated portion and the current collector terminal can be sufficiently ensured.
In addition, the layers of the current collector laminated portion are in close contact with each other at the stretched portion (welded location) by the amount of the current collector laminated portion being stretched, and the distance between the layers is shortened. Therefore, the contact resistance is reduced. Therefore, the current density of the current flowing through the welded portion is increased. That is, the electrical conductivity of the welding location is improved. Therefore, since heat is generated efficiently, welding can be performed with sufficient strength even with a smaller current than before.
In addition, since welding can be performed with a smaller current than in the past, excessive heat generation at the welding point caused by flowing a large current can be prevented. As a result, it is possible to prevent the occurrence of spatter due to excessive heat generation. Moreover, since spatter does not scatter to the laminated part side electrode, it is possible to prevent damage to the welded part of the current collector laminated part and damage to the laminated part side electrode.

Here in the secondary battery of the production method of the present invention, the pressing force applied between the terminal-side electrode and the laminated portion side electrode, as the pressure is desirably ^{142N / mm 2 ~424N / mm 2} .
If it does in this way, the contact surface of the lamination | stacking part side electrode can fully be made to bite with respect to a collector laminated part. Therefore, it is possible to satisfactorily resistance-weld the current collector laminated portion and the current collector terminal without causing spattering.

In the method for manufacturing a secondary battery according to the present invention, the regular uneven shape of the contact surface of the laminated portion side electrode has a plurality of concentric circles at predetermined intervals from the center of the contact surface to the outside. The formed shape is desirable.
In this way, it is possible to increase the welding strength as compared with the case where the laminated portion side electrode in which other shapes (for example, a lattice shape or a stripe shape) are uneven is used.

In the method for manufacturing a secondary battery according to the present invention, it is desirable that the regular uneven shape of the contact surface is formed by electric discharge machining.
If the concave and convex shape is applied by electric discharge machining, a regular concave and convex shape can be obtained, so that the current flowing during resistance welding can be prevented from being dispersed and good welding can be performed.

  The secondary battery according to the present invention includes a positive electrode plate having a positive electrode active material layer formed on the surface of a foil-shaped positive electrode current collector, and a negative electrode active material layer formed on the surface of the foil-shaped negative electrode current collector. A secondary battery comprising: a wound electrode body formed by winding a negative electrode plate together with a separator; and a current collecting terminal for each of positive and negative electrodes joined to the wound electrode body. One end of the axial end portions is a positive electrode current collector laminated portion laminated in a state where a positive electrode active material layer non-formed portion where a positive electrode active material layer is not formed protrudes from the negative electrode plate, The other end of the two end portions is a negative electrode current collector laminated portion in which a negative electrode active material layer non-formed portion where no negative electrode active material layer is formed is laminated in a state of protruding from the positive electrode plate. The current collector laminate portion of at least one of the electrode laminate portion and the negative electrode current collector laminate portion is collected by resistance welding. The weld mark formed on the surface of the current collector stack by resistance welding is a regular uneven shape with a maximum roughness (Rmax) of 9 μm to 25 μm. Features.

  When resistance welding is performed using the laminated portion side electrode having a regular uneven contact surface with the maximum roughness (Rmax) of 15 μm to 25 μm, the resistance welding weld trace formed on the current collector laminated portion is The surface roughness is a regular uneven shape having a maximum roughness (Rmax) of 9 μm to 25 μm. Therefore, according to the secondary battery of the present invention, a battery having no poor welding is provided for the reasons described above. In addition, since the secondary battery of the present invention suppresses the occurrence of spatter during welding in the manufacturing process, it is a battery that can prolong the life of the laminated part side electrode for resistance welding.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and secondary battery of a secondary battery which can carry out resistance welding of a collector laminated part and a current collection terminal favorably without causing generation | occurrence | production of a sputter | spatter are provided.

It is sectional drawing which shows the secondary battery which concerns on 1st Embodiment. It is a figure which shows the structure of the winding electrode body with which the secondary battery is equipped. It is a figure which shows a mode that resistance welding is carried out in 1st Embodiment, and is a figure which shows a mode that the collector terminal and the collector laminated part are pinched | interposed by a pair of electrodes. It is the photograph which expanded the contact surface of the lamination | stacking part side electrode. It is the photograph which expanded the welding trace of the collector laminated part. It is sectional drawing which shows the secondary battery which concerns on 2nd Embodiment. It is VII-VII sectional drawing shown in FIG. It is a perspective view of the current collection terminal with which the secondary battery is provided. It is a figure which shows a mode that resistance welding is performed in 2nd Embodiment, and is a figure which shows a mode that the current collection terminal and the current collector laminated part are inserted | pinched by a pair of electrodes. It is XX sectional drawing shown in FIG. It is the photograph which expanded the contact surface of the lamination | stacking part side electrode in the resistance welding machine used by a prior art. It is the photograph which expanded the welding trace of the collector lamination part at the time of resistance welding using the lamination | stacking part side electrode of the contact surface shown in FIG.

(First embodiment)
Hereinafter, embodiments of the secondary battery of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a secondary battery 100 according to the first embodiment. As shown in FIG. 1, the secondary battery 100 according to the first embodiment (hereinafter also simply referred to as “battery 100”) includes a rectangular battery case 180 and a flat battery case accommodated in the battery case 180. The prismatic lithium ion secondary battery includes a rotating electrode body 110. The battery 100 is mounted as a power source in a vehicle such as a hybrid car or an electric vehicle, or a battery-powered device such as a hammer drill. In this specification, unless otherwise specified, the top, bottom, left, and right refer to FIG. 1, and the front side of the page in FIG. 1 is the front and the back side of the page is the back.

  The battery case 180 is made of aluminum and has a battery case main body 181 and a sealing lid 182. Among these, the sealing lid 182 has a rectangular plate shape, closes the upper opening of the battery case body 181, and is welded to the battery case body 181. A rectangular plate-shaped safety valve 197 is sealed on the sealing lid 182.

  The battery case body 181 has a bottomed rectangular box shape with an open top, and houses a flat wound electrode body 110 therein. More specifically, the battery case main body 181 includes a rectangular plate-like case bottom wall portion 181b facing the sealing lid 182, and four case side wall portions 181c standing upward from the periphery of the case bottom wall portion 181b. ing.

  The wound electrode body 110 is a wound electrode body in which a belt-like positive electrode plate 130 and a negative electrode plate 120 are wound into a flat shape via a belt-like separator 150. The wound electrode body 110 is housed in the battery case 180 in a state where the wound axis direction AX is in the horizontal direction. A plate-like positive current collecting terminal 191 bent in a crank shape is joined to the positive electrode plate 130 by ultrasonic welding. Further, a plate-shaped negative electrode current collecting terminal 192 bent in a crank shape is joined to the negative electrode plate 120 by resistance welding. The resistance welding of the negative electrode current collector terminal will be described in detail later. Note that the positive electrode current collector terminal 191 is made of the same material (aluminum in this embodiment) as the positive electrode current collector 131 described later. The negative electrode current collector terminal 192 is made of the same material (copper in this embodiment) as the negative electrode current collector 121 described later.

  Of the positive electrode current collecting terminal 191 and the negative electrode current collecting terminal 192, the positive electrode external terminal portion 191a and the negative electrode external terminal portion 192a located at the respective tips penetrate the sealing lid 182 of the battery case 180 and protrude from the lid surface 182A. Yes. Insulating members 195 made of an electrically insulating resin are interposed between the positive external terminal portion 191a and the sealing lid 182 and between the negative external terminal portion 192a and the sealing lid 182, respectively.

FIG. 2 is a view showing the structure of the wound electrode body 110. As shown in FIG. 2, the positive electrode plate 130 includes a strip-shaped positive electrode current collector (positive electrode current collector plate) 131 made of an aluminum foil extending in the longitudinal direction DA (vertical direction in FIG. 2), and the positive electrode current collector. And a positive electrode active material layer 132 coated on a part of the surface of 131. The positive electrode active material layer 132 includes, for example, a positive electrode active material 133 made of lithium cobalt oxide (LiCoO ₂ ), a conductive material made of acetylene black, and a binder made of polyvinylidene fluoride (PVDF).

  A portion of the positive electrode current collector 131 where the positive electrode active material layer 132 is coated is referred to as a positive electrode active material layer forming portion (positive electrode mixture layer coating portion) 131c. On the other hand, a portion where the positive electrode active material layer 132 is not coated is referred to as a positive electrode active material layer non-formed portion (positive electrode mixture layer uncoated portion) 131b. The positive electrode active material layer non-forming part 131b is located at the end (left end in FIG. 2) of the width direction DB (left and right in FIG. 2) of the positive electrode current collector 131 (positive electrode plate 130). It extends in a strip shape along the longitudinal direction DA of the (positive electrode plate 130).

  The negative electrode plate 120 includes a strip-shaped negative electrode current collector (negative electrode current collector plate) 121 made of a copper foil extending along the longitudinal direction DA, and a negative electrode active material coated on a part of the surface of the negative electrode current collector 121. The material layer 122 is included. The negative electrode active material layer 122 includes, for example, a negative electrode active material 123 made of graphite (graphite), a binder made of SBR, and a thickener made of CMC.

  A portion of the negative electrode current collector 121 where the negative electrode active material layer 122 is coated is referred to as a negative electrode active material layer forming portion (negative electrode mixture layer coating portion) 121c. On the other hand, a portion of the negative electrode current collector 121 where the negative electrode active material layer 122 is not coated is referred to as a negative electrode active material layer non-formed portion (negative electrode mixture layer uncoated portion) 121b. The negative electrode active material layer non-forming portion 121b is located at the end portion (right end portion in FIG. 2) of the negative electrode current collector 121 (negative electrode plate 120) in the width direction DB, and the longitudinal direction of the negative electrode current collector 121 (negative electrode plate 120). It extends in a band shape along the direction DA.

The separator 150 is made of polyethylene, for example, and is interposed between the positive electrode plate 130 and the negative electrode plate 120 to separate them. The separator 150 is impregnated with an electrolytic solution 160 having lithium ions as shown in FIG. The electrolyte 160 is, for example, lithium hexafluorophosphate (LiPF) as a solute in a mixed organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are adjusted to EC: EMC = 3: 7 by volume ratio. ₆ ) is a non-aqueous electrolyte with a lithium ion concentration of 1 mol / L.

  As shown in FIG. 1, the wound electrode body 110 configured as described above includes a positive electrode current collector laminated portion 136 formed by winding the positive electrode active material layer non-forming portion 131 b so as to protrude from the negative electrode plate 120. , At one end (left end) along the winding axis direction. The positive electrode current collector laminated portion 136 is a portion where the lower end portion of the positive electrode current collector terminal 191 is welded by ultrasonic welding. The code | symbol 137 in FIG. 1 has shown the welding trace of ultrasonic welding. By this welding, the positive electrode current collecting terminal 191 and the wound electrode body 110 are electrically and mechanically connected.

  Further, the wound electrode body 110 includes a negative electrode current collector laminated portion 126 formed by winding the negative electrode active material layer non-forming portion 121b in a state of protruding from the positive electrode plate 130, and the other end portion along the winding axis direction ( Right end). The negative electrode current collector laminated portion 126 is a portion where the lower end portion of the negative electrode current collector terminal 192 is welded by resistance welding. Reference numeral 127 in FIG. 1 indicates a welding mark of resistance welding. By this welding, the negative electrode current collector terminal 192 and the wound electrode body 110 are electrically and mechanically connected.

  In the wound electrode body 110, the power generation unit 116 is located between the positive electrode current collector stacking portion 136 and the negative electrode current collector stacking portion 126. The power generation unit 116 includes a positive electrode active material layer forming unit 131c (a portion where the positive electrode active material layer 132 of the positive electrode plate 130 is formed, see FIG. 2) and a negative electrode active material layer forming unit 121c (a negative electrode active material of the negative electrode plate 120). The portion where the layer 122 is formed (see FIG. 2) and the portion where the separator 150 is wound.

  Next, the manufacturing process of the battery 100 of this embodiment will be briefly described. First, a sealing lid 182 assembled with the wound electrode body 110, the battery case body 181, and the current collecting terminals 191 and 192 configured as described above is prepared.

  Next, as shown in FIG. 1, the positive electrode current collector terminal 191 is joined to the positive electrode current collector laminated portion 136 of the wound electrode body 110 by ultrasonic welding. Further, the negative electrode current collector terminal 192 is resistance-welded to the negative electrode current collector laminated portion 126 of the wound electrode body 110.

  Subsequently, the wound electrode body 110 is accommodated in the battery case body 181 and the battery case body 181 is closed by the sealing lid 182. Then, the sealing lid 182 and the battery case body 181 are joined by laser welding.

  After the sealing lid 182 and the battery case body 181 are joined by laser welding, the electrolytic solution is injected into the battery case body 181 through a liquid injection port (not shown) and impregnated in the wound electrode body 110. Then, the liquid injection port is sealed by inserting a liquid injection stopper into the liquid injection port. Thereafter, the battery 100 of this embodiment (see FIG. 1) is completed by performing predetermined processing.

  Next, the joining of the negative electrode current collector terminal 192 and the negative electrode current collector laminated portion 126 by resistance welding will be described in detail. As shown in FIG. 3, resistance welding includes a pair of electrodes (terminal-side electrode 20 and laminated portion-side electrode 30) sandwiching the objects to be joined (negative electrode collector terminal 192 and negative electrode collector laminated portion 126), and negative electrode While pressurizing the current collector terminal 192 and the negative electrode current collector stacking portion 126 (while applying a pressing force to the negative electrode current collector terminal 192 and the negative electrode current collector stacking portion 126), the electrodes 20 and 30 are energized to generate joules. This is a welding method in which the objects to be joined are melted and joined by generating heat. Note that the negative electrode current collector terminal 192 is joined by resistance welding because copper used on the negative electrode side has a higher thermal conductivity than aluminum used on the positive electrode side. This is because it can be satisfactorily bonded.

  Here, in the resistance welding machine used for manufacturing the battery 100 of the present embodiment, the contact surface 31 (see FIG. 3) of the laminated portion side electrode 30 with respect to the negative electrode current collector laminated portion 126 has a maximum roughness (Rmax) of 15 μm to 15 μm. The surface is uneven with a surface roughness of about 25 μm. The maximum roughness (Rmax) is the maximum roughness of the JIS standard. The surface roughness of the contact surface of the laminated portion side electrode of the resistance welding machine that has been conventionally used was about 1 μm to 10 μm in maximum roughness (Rmax). Therefore, it can be said that the contact surface 31 of the laminated portion side electrode 30 of the resistance welding machine used for manufacturing the battery 100 of this embodiment is rougher than the conventional one.

  FIG. 4 is a photograph of the contact surface 31 of the laminated portion side electrode 30 of the resistance welder used for manufacturing the battery 100 of the present embodiment as viewed with a microscope. FIG. 11 is a photograph of the contact surface 50 of the current collecting side electrode of a conventional resistance welder viewed with a microscope. 4 and 11, the contact surface 31 of the laminated portion side electrode 30 of the resistance welder used for welding the battery 100 of this embodiment is more than the contact surface 50 of the current collector side electrode of the conventional resistance welder. It can be seen that the unevenness is severe and rough. The unevenness of the contact surface 31 is formed by electric discharge machining. As shown in FIG. 4, the unevenness of the contact surface 31 of this embodiment is concentrically provided. Specifically, the unevenness of the contact surface 31 is provided in a shape in which a plurality of concentric circles are formed at a pitch of 0.2 mm from the center of the circular contact surface 31 toward the radially outer side.

  A welding mark 127 shown in FIG. 1 is formed in the negative electrode current collector laminated portion 126 by pressing the laminated portion side electrode 30 having the contact surface 31 and performing resistance welding. FIG. 5 is a photograph of this weld mark 127 viewed with a microscope. The weld mark 127 has a regular uneven shape with a surface roughness of 9 μm to 25 μm. The reason why the weld mark 127 has a regular uneven shape with a maximum roughness (Rmax) of 9 μm to 25 μm is that the laminated portion side electrode 30 having a contact surface 31 rougher than that of the conventional technique is laminated to the negative electrode current collector during resistance welding. This is because, when pressed against the welded portion of the portion 126, the bite is deeper than before. Therefore, irregularities are transferred to the welded portion of the negative electrode current collector laminated portion 126.

  On the other hand, when resistance welding is performed by a conventional resistance welding machine, the degree of unevenness transferred to the current collector laminate is small. FIG. 12 is a photograph of a welding trace formed on the current collector laminated portion as seen with a microscope by performing resistance welding with a conventional resistance welder. The surface roughness of the welding mark 60 shown in FIG. 12 is a maximum roughness (Rmax) of 4 μm to 8 μm, which is not rougher than the welding mark 127 of the present embodiment. This is because the surface roughness of the contact surface 50 (FIG. 11) of the laminated portion side electrode in the conventional resistance welding machine is not rough as in the present embodiment, so even if the laminated portion side electrode is pressed against the current collector laminated portion. This is because it does not penetrate deeply as in this embodiment.

  Next, the results of tests performed to confirm the effect of the battery 100 of the present embodiment will be described based on Tables 1 and 2 below.

Examples 1 to 12 in Table 1 and Comparative Examples 1 to 10 in Table 2 are batteries configured as follows.
Example 1
The positive electrode plate 130 is prepared by forming a positive electrode active material layer 132 on a positive electrode current collector 131 of an aluminum foil or aluminum alloy foil having a thickness of about 15 μm.

  The negative electrode plate 120 is prepared by forming a negative electrode active material layer 122 on a negative electrode current collector 121 of an electric field copper foil having a thickness of about 10 μm.

  The prepared positive electrode plate 130 and negative electrode plate 120 are wound into a flat shape with a separator 150 made of a porous synthetic resin interposed therebetween to form a wound electrode body 110 having a battery capacity of 3.6 Ah. At this time, the positive electrode current collector laminated portion 136 is formed at one end along the winding axis direction of the wound electrode body 110, and the negative electrode current collector laminated portion 126 is formed at the other end.

  Furthermore, a positive electrode current collector terminal 191 made of aluminum having a thickness of about 1.5 mm is prepared, bent into a shape along the wound electrode body 110, and the wound electrode body 110 is connected to the positive electrode current collector stack portion 136. Press work so that the welded portion has a thickness of about 1 mm.

  A negative electrode current collector terminal 192 made of copper having a thickness of about 1.0 mm is prepared, bent into a shape along the wound electrode body 110, and a welded portion of the wound electrode body 110 to the negative electrode current collector laminated portion 126 Is pressed to a thickness of about 0.6 mm.

  The positive electrode current collector terminal 191 and the negative electrode current collector terminal 192 are assembled to an aluminum sealing lid 182. Then, the negative electrode current collector terminal 192 is joined to the negative electrode current collector laminated portion 126 by resistance welding, and the positive electrode current collector terminal 191 is joined to the positive electrode current collector laminated portion 136 by ultrasonic welding.

  In resistance welding on the negative electrode side, a DDC welder NDWS5500-4M manufactured by Nag Systems Co., Ltd. was used as a resistance welding machine. The resistance welding electrode (lamination part side electrode 30) of this resistance welder is made of tungsten, and the diameter of the tip surface (contact surface 31) is about 3 mm.

  Here, unevenness is given to the front end surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) by electric discharge machining. Concavities and convexities are provided concentrically. Specifically, the unevenness is provided in a shape in which a plurality of concentric circles are formed at a pitch of 0.2 mm toward the radially outer side of the tip surface (contact surface 31) (see FIG. 4). The degree of unevenness is about 15 μm in terms of the maximum roughness Rmax. Using this resistance welder, resistance welding was performed with a set voltage of 10 V, a welding time of 6 hours, and a pressing force applied to the negative electrode current collector terminal 192 and the negative electrode current collector laminated portion 126 by a pair of electrodes was 3.0 kN. It was.

  In ultrasonic welding on the positive electrode side, 2000Xdt20: 2.5 power supply (2500 W) manufactured by Nippon Emerson Co., Ltd. was used as an ultrasonic welding machine. Using this ultrasonic welder, ultrasonic welding was performed with an energy of 500 J, a trigger pressure of 800 N, and an amplitude of 50%.

  Thereafter, the wound electrode body 110 was accommodated in the battery case body 181 and the sealing lid 182 was joined to the battery case body 181 by laser welding. And the electrolyte solution 160 was inject | poured and sealed from the injection hole formed in the sealing lid 182, and the battery 100 was completed.

(Example 2)
Example 2 was carried out except that the unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was a grid shape with a pitch of 0.2 mm. Same as Example 1. The degree of unevenness in Example 2 is about 15 μm in maximum roughness Rmax, as in Example 1.

Example 3
Example 3 was carried out except that the unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was a stripe shape with a pitch of 0.2 mm. Same as Example 1. The degree of unevenness in Example 3 is about 15 μm in the maximum roughness Rmax as in Example 1.

Example 4
In Example 4, the degree of unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) is about 20 μm in terms of the maximum roughness Rmax. , The same as in the first embodiment. In addition, the unevenness | corrugation of Example 4 is the concentric form of a 0.2 mm pitch similarly to Example 1. FIG.

(Example 5)
In Example 5, the degree of unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) is about 25 μm in maximum roughness Rmax. , The same as in the first embodiment. In addition, the unevenness | corrugation of Example 5 is the concentric form of a 0.2 mm pitch similarly to Example 1. FIG.

(Example 6)
Example 6 was carried out except that the unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was a grid shape with a pitch of 0.15 mm. Same as Example 1. The degree of unevenness in Example 6 is about 15 μm in the maximum roughness Rmax as in Example 1.

(Example 7)
Example 7 is the same as Example 1 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

(Example 8)
Example 8 is the same as Example 2 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminate 126 during resistance welding is 1.0 kN.

Example 9
Example 9 is the same as Example 3 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminate 126 during resistance welding is 1.0 kN.

(Example 10)
Example 10 is the same as Example 4 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminate 126 during resistance welding is 1.0 kN.

(Example 11)
Example 11 is the same as Example 5 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminate 126 during resistance welding is 1.0 kN.

(Example 12)
Example 12 is the same as Example 6 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

(Comparative Example 1)
In Comparative Example 1, the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was polished with abrasive paper, so that the degree of unevenness was about 1 μm with the maximum roughness Rmax. Except for this, this example is the same as Example 1.

(Comparative Example 2)
In Comparative Example 2, the tip surface (contact surface 31) of the resistance welding electrode (lamination portion side electrode 30) was polished with abrasive paper, so that the degree of unevenness was about 4 μm with a maximum roughness Rmax. Other than the above, the second embodiment is the same as the first embodiment.

(Comparative Example 3)
In Comparative Example 3, the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was polished with abrasive paper, so that the degree of unevenness was about 10 μm with a maximum roughness Rmax. Except for this, this example is the same as Example 1.

(Comparative Example 4)
In Comparative Example 4, the degree of unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) is about 13 μm in terms of the maximum roughness Rmax. , The same as in the first embodiment. In addition, the unevenness | corrugation of the comparative example 4 is the concentric form of a 0.2 mm pitch similarly to Example 1. FIG.

(Comparative Example 5)
In Comparative Example 5, the degree of unevenness formed by electric discharge machining on the tip surface (contact surface 31) of the electrode for resistance welding (laminated portion side electrode 30) is about 30 μm at the maximum roughness Rmax. , The same as in the first embodiment. In addition, the unevenness | corrugation of the comparative example 5 is the concentric form of a 0.2 mm pitch similarly to Example 1. FIG.

(Comparative Example 6)
In Comparative Example 6, the tip surface (contact surface 31) of the resistance welding electrode (laminated portion side electrode 30) was roughened by sandblasting. The degree of unevenness applied is about 25 μm with a maximum roughness Rmax. The rest is the same as the first embodiment. In addition, the unevenness | corrugation given by sandblasting is not a regular shape unlike the unevenness | corrugation given by electric discharge machining.

(Comparative Example 7)
Comparative Example 7 is the same as Comparative Example 1 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

(Comparative Example 8)
Comparative Example 8 is the same as Comparative Example 2 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

(Comparative Example 9)
Comparative Example 9 is the same as Comparative Example 3 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

(Comparative Example 10)
Comparative Example 10 is the same as Comparative Example 4 except that the load (pressing force) applied to the negative electrode current collector terminal 191 and the negative electrode current collector laminated portion 126 during resistance welding is 1.0 kN.

  Regarding Table 1 and Table 2, the maximum roughness (Rmax) of the contact surface 31 of the laminated portion side electrode 30 and the weld mark 127 of the negative electrode current collector laminated portion 126 was measured using a 3D laser microscope. The number of spatters generated is the number of sputters of 50 μm to 200 μm scattered outside the welded part, and was measured using a particle counter (fine particle measuring device). The welding strength is obtained by fixing the wound electrode body 110 to a tensile tester, grasping the upper end of the negative electrode current collecting terminal 192 and pulling it up, and measuring the peak strength. In the electrode life column, every time the number of welding reaches 100 times, the contact surface of the resistance welding electrode to the object to be welded is observed for changes such as cracks, and the number of times when there is a change is noted. ing.

  The battery voltage failure after the initial charge / discharge is the number of batteries with a voltage failure found as follows. As the initial charge / discharge, first, constant current charge was performed for 2 hours at a charge rate of 1 / 5C. Next, after resting for 10 minutes, constant current discharge was performed at a discharge rate of 1/5 C until the battery voltage reached 3.0V. Furthermore, after 10 minutes of rest, the battery was charged at a constant current until the battery voltage reached 4.1 V at a charge rate of 1/3 C, and then charged at a constant voltage until the charging current reached 2/100 C. Subsequently, after a pause of 10 minutes, constant current discharge was performed at a discharge rate of 1/3 C until the battery voltage reached 3.0 V, and then discharge was performed at a constant voltage until the discharge current reached 2/100 C. Furthermore, after resting for 10 minutes, constant current charging was performed until the battery voltage reached 4.1 V at a charging rate of 1 / 5C. The battery that had been subjected to such initial charge / discharge was placed in an environment of 45 ° C. for 24 hours, and the battery voltage (referred to as V1) when 24 hours passed was measured. Then, it was left in an environment of 25 ° C. for 4 days, and the battery voltage (referred to as V2) when 4 days passed was measured. Then, it is determined whether or not the value of V1-V2 is within a predetermined reference value range. If the value is outside the reference value range, a battery with a voltage failure is obtained. The reason why the value of V1-V2 deviates from the range of the reference value is due to a voltage drop due to a short circuit.

The following can be understood from the experimental results shown in Tables 1 and 2 above.
In Examples 1-12, spatter did not generate | occur | produce, welding strength was higher than Comparative Examples 1-4 and 7-10, and the lifetime of the electrode of the resistance welder was long. In Examples 1-12, when the welding trace 127 of the negative electrode collector laminated part 126 was observed, the unevenness | corrugation of the contact surface 31 of the laminated part side electrode 30 was transcribe | transferred in any Example. Further, the thickness of the welded portion of the negative electrode current collector laminated portion 126 was thinner than before welding. From this, it can be seen that, during resistance welding, the contact surface 31 having a maximum roughness of 15 to 25 μm is pressed, whereby the negative electrode current collector laminated portion 126 is stretched and the welding area is expanded. Further, since the layers of the negative electrode current collector stack 126 are in close contact with each other, the contact resistance between the layers is lowered. Therefore, it is considered that the conductivity is improved and welding with high strength is possible.

  On the other hand, in Comparative Examples 1-4 and 7-10, when the welding trace 127 of the negative electrode collector laminated part 126 was observed, the unevenness | corrugation of the contact surface 31 of the laminated part side electrode 30 was not transcribe | transferred, but a welding location The thickness of each was thicker than in each example, and the weld area was smaller than in each example. Further, when the welded part was peeled off and observed, in particular, in Comparative Examples 1 and 2, the central part in the stacking direction of the negative electrode current collector stacking part 126 was not welded. In Comparative Examples 3 and 4, the welding of the negative electrode current collector terminal 192 and the negative electrode current collector laminated portion 126 was weak. Further, in Comparative Examples 7 to 10, the welding of each layer of the negative electrode current collector laminated portion 126 was weak. Therefore, in Comparative Examples 1 to 4 and 7 to 10, even when the contact surface 31 having a maximum roughness of 13 μm or less is pressed during resistance welding, the negative electrode current collector laminated portion 126 is not stretched so much and the welding area is increased. It turns out that it does not expand. Therefore, it is considered that the contact resistance between the layers of the negative electrode current collector laminated portion 126 is high and the conductivity is worse than that of the example. As a result, the current density of the current that flows during resistance welding is low and does not generate enough heat.

  In Comparative Examples 5 and 6, sufficient welding strength was obtained, but spatter adhesion was observed on the surface of the electrode for resistance welding. In Comparative Example 5, since the maximum roughness of the contact surface 31 of the laminated portion side electrode 30 is as large as 30 μm, the negative electrode current collector laminated portion 126 does not stretch in close contact with the unevenness of the contact surface 31, It is considered that a gap was formed between the contact surface 31 of the laminated portion side electrode 30 and the negative electrode current collector laminated portion 126. If the gap is formed, the contact area between the contact surface 31 of the laminated portion side electrode 30 and the negative electrode current collector laminated portion 126 is reduced, so that a large current flows locally and spatter is generated. it is conceivable that.

  Further, in Comparative Example 6, since the irregularities formed on the contact surface 31 of the laminated portion side electrode 30 are irregular irregularities formed by sandblasting, it is considered that the current flowing during resistance welding has been dispersed. It is done. In other words, it is thought that there were places where currents were easy to flow and where currents were difficult to flow during resistance welding. For this reason, it is thought that the part where current easily flows melted and spatter occurred.

  Furthermore, in Comparative Examples 1-10, the lifetime of the electrode of a resistance welder is short. This is probably because the current in each of the comparative examples does not flow more efficiently than in each of the examples, and the electrode of the resistance welder generates heat and the oxidation of the electrode surface is accelerated. In addition, it is considered that in Comparative Examples 5 and 6, spatter adheres to the electrodes of the resistance welder, and cracks starting from the adhered portions are likely to occur.

  Furthermore, in Comparative Examples 5 and 6, voltage failure after initial charge / discharge also occurs. This is considered to be because the generated spatter mixed into the wound electrode body 110, causing a short circuit and causing a voltage drop.

  From the above experimental results, good welding can be performed if the contact surface 31 of the laminated portion side electrode 30 of the resistance welder is an uneven surface having a regular uneven shape with a maximum roughness of about 15 μm to 25 μm. I knew it was possible.

As described above, the method of manufacturing the battery 100 according to this embodiment includes the positive electrode plate 130 in which the positive electrode active material layer 132 is formed on the surface of the foil-shaped positive electrode current collector 131, and the foil-shaped negative electrode current collector. By winding the negative electrode plate 120 having the negative electrode active material layer 122 formed on the surface of 121 together with the separator 150, at one end (left end in FIG. 1) of both ends in the winding axis direction. The positive electrode active material layer non-formed portion 131b in which the positive electrode active material layer 132 is not formed has a positive electrode current collector laminated portion 136 laminated in a state of protruding from the negative electrode plate 120, and the other end of the both ends. Part (right end in FIG. 1) has a negative electrode current collector laminated part 126 in which a negative electrode active material layer non-formed part 121b in which the negative electrode active material layer 122 is not formed is laminated in a state of protruding from the positive electrode plate 130. A wound electrode body 110 is produced. And the extent,
A step of disposing a positive electrode current collector terminal 191 on the positive electrode current collector laminated portion 136 and joining them by ultrasonic welding;
Disposing a negative electrode current collector terminal 192 in the negative electrode current collector stack 126;
The negative electrode current collector laminated portion 126 in which the terminal electrode 20 for resistance welding (see FIG. 3) is brought into contact with the negative electrode current collector terminal 192 arranged in the negative electrode current collector laminated portion 126 and the negative electrode current collector terminal 192 is arranged. And sandwiching the negative electrode current collector terminal 192 and the negative electrode current collector laminated portion 126 by contacting the terminal side electrode 20 and the pair of laminated portion side electrodes 30 (see FIG. 3),
And performing resistance welding while applying a pressing force between the terminal side electrode 20 and the laminated part side electrode 30.
And in the laminated part side electrode 30 used for this resistance welding, the contact surface 31 with respect to the negative electrode collector laminated part 126 becomes an uneven surface having a regular uneven shape with a maximum roughness (Rmax) of 15 μm to 25 μm. Is used.

  The laminated portion side electrode 30 used in the manufacturing method of the battery 100 of the present embodiment has a regular uneven shape in which the contact surface 31 to the negative electrode current collector laminated portion 126 has a surface roughness (maximum roughness Rmax) of 15 μm to 25 μm. It is an uneven surface having That is, the contact surface 31 is rougher than the laminated portion side electrode of the conventional resistance welder. Therefore, the laminated portion side electrode 30 bites into the negative electrode current collector laminated portion 126 by pressurization during resistance welding. The degree of this biting is such that the unevenness of the contact surface 31 of the laminated portion side electrode 30 moves into the negative electrode current collector laminated portion 126. The degree of unevenness transferred to the negative electrode current collector stack 126 is about 9 to 25 μm in terms of the maximum roughness Rmax. Thus, since the laminated part side electrode 30 bites into the negative electrode current collector laminated part 126, the negative electrode current collector laminated part 126 is extended (stretched). Therefore, the contact area between the laminated portion side electrode 30 and the negative electrode current collector laminated portion 126 increases. Therefore, the welding strength between the negative electrode current collector stack 126 and the negative electrode current collector terminal 192 can be sufficiently secured.

  Further, the layers of the negative electrode current collector stacking portion 126 are brought into close contact with each other at the extended portion (welded portion) by the amount of the negative electrode current collector stacking portion 126 being stretched, and the distance between the layers is shortened. Therefore, the contact resistance is reduced. Therefore, the current density of the current flowing through the welded portion is increased. That is, the electrical conductivity of the welding location is improved. Therefore, since heat is generated efficiently, welding can be performed with sufficient strength even with a smaller current than before.

  In addition, since welding can be performed with a smaller current than in the past, excessive heat generation at the welding point caused by flowing a large current can be prevented. As a result, it is possible to prevent the occurrence of spatter due to excessive heat generation. Moreover, since spatter does not scatter to the laminated portion side electrode 30, damage to the welded portion of the negative electrode current collector laminated portion 126 and damage to the laminated portion side electrode 30 can be prevented.

Moreover, according to the manufacturing method of the battery 100 of this embodiment, since the spatter can be prevented as described above, the occurrence of voltage failure of the battery 100 can be suppressed.
Furthermore, since it is not necessary to pass a large current to the electrodes 20 and 30 during resistance welding, the generation of cracks due to thermal shock can be suppressed, and the life of the electrodes 20 and 30 can be extended.
In addition, since the maximum roughness (Rmax) of the contact surface 31 of the stacked portion side electrode 30 is 25 μm or less, the contact surface 31 is pressed when the stacked portion side electrode 30 is pressed against the negative electrode current collector stacked portion 126. The negative electrode current collector laminated portion 126 can be in close contact with the concavo-convex portion without any gap. For this reason, it is possible to prevent the current flowing during resistance welding from being concentrated on a part of the welded portion, thereby significantly suppressing the generation of spatter.

Here, in the manufacturing method of the battery 100 of this embodiment, it is desirable that the pressing force applied between the terminal side electrode 20 and the laminated portion side electrode 30 is 1.0 kN to 3.0 kN (see Table 1). In addition, the desirable range of this pressing force is a thing when the diameter of the contact surface 31 is about 3 mm as the laminated part side electrode 30 as mentioned above. That is, in the manufacturing method of the battery 100 of the present embodiment, the pressing force applied between the terminal-side electrode 20 and the laminated portion side electrode 30, as the pressure ^is desirably ^{142N / mm 2 ~424N / mm 2} .

  In this way, the contact surface 31 of the laminated portion side electrode 30 can be sufficiently bite into the negative electrode current collector laminated portion 126. Therefore, the negative electrode current collector stack 126 and the negative electrode current collector terminal 192 can be resistance-welded satisfactorily without causing spatter.

  In addition, in the manufacturing method of the battery 100 according to the present embodiment, the laminated portion side electrode 30 having concentric irregularities as shown in FIG. 4 on the contact surface 31 to the negative electrode current collector laminated portion 126 is used. . Therefore, it is possible to increase the welding strength as compared with the case of using the laminated portion side electrode in which the other shapes (lattice shape and stripe shape) are uneven (see Examples 1 to 3 in Table 1).

  In the method for manufacturing the battery 100 according to this embodiment, the laminated portion side electrode 30 is used in which the contact surface 31 to the negative electrode current collector laminated portion 126 is uneven by electric discharge machining. If irregularities are formed by electric discharge machining, a regular irregular shape can be obtained, so that it is possible to prevent the current flowing during resistance welding from being dispersed and to perform good welding (Examples 1 and 2 in Table 1). (See Comparative Example 6).

(Second Embodiment)
Hereinafter, a second embodiment will be described with reference to FIGS. A lithium ion secondary battery 100A (hereinafter also simply referred to as “battery 100A”) according to the second embodiment shown in FIG. 6 includes two negative electrode current collector stacking portions 126A as seen from the left side as shown in FIG. The negative electrode current collecting terminal 192A is disposed therebetween. Similarly, the positive electrode current collector laminated portion 136A (see FIG. 6) is also divided into two, and the positive electrode current collector terminal 191A (see FIG. 6) is disposed therebetween. The joining of the positive current collector terminal 191A to the positive current collector laminated portion 136A is the same as that on the negative electrode side, and thus the description thereof is omitted. Since the other configuration is the same as that of the battery 100 of the first embodiment, the same reference numerals as those of the first embodiment are given and description thereof is omitted.

  In the battery 100A of the second embodiment, as shown in FIGS. 6, 7 and 8, the negative electrode current collecting terminal 192 </ b> A includes a plate-like extending portion 193 that is thin in the left-right direction and front and rear ends of the extending portion 193. Two opposing current collecting connections 194, 194 extending to the right from the lower part. The current collector connection portions 194 and 194 are plate-shaped that are thin in the front-rear direction.

  As shown in FIG. 7, the negative electrode current collector stack portion 126A is divided into a front negative electrode current collector stack portion 126Aa and a rear negative electrode current collector stack portion 126Ab. A portion of the negative electrode current collector laminated portion 126A located outside as viewed in the radial direction of the wound electrode body 110 is referred to as an outer uncoated portion 128. In addition, a portion of the negative electrode current collector laminated portion 126A that is located on the inner side when viewed in the radial direction of the wound electrode body 110 is referred to as an inner uncoated portion 129. The radial direction of the wound electrode body 110 is a direction from the center (position of the winding axis AX) of the wound electrode body 110 toward the outer side (outer peripheral side).

  The two current collector connecting portions 194, 194 of the negative electrode current collector terminal 192A are not welded from the outer uncoated portion 128 side of the negative electrode current collector stacking portion 126A, but are welded from the inner uncoated portion 129 side. (See FIG. 7). Specifically, the two current collector connection portions 194 and 194 are inserted into a space located at the center of the wound negative electrode current collector laminated portion 126A, and are outside the current collector connection portions 194 and 194. They are welded to the inner uncoated portions 129 and 129 located on the right and left sides in FIG.

  By welding the negative electrode current collector terminal 192A from the inner uncoated portions 129 and 129 in this way, the heat of the radially inner portion where the temperature of the wound electrode body 110 is relatively high is increased. It can be transmitted (released) to the negative electrode current collecting terminal 192A through the portion 129. And it can discharge | release to the battery exterior further from negative electrode current collection terminal 192A. On the other hand, since the negative electrode current collector terminal 192A is not welded from the outer uncoated portion 128 side, the heat at the radially outer portion where the temperature is relatively low is hardly transmitted (released) to the negative electrode current collector terminal 192A. . Therefore, according to the lithium ion secondary battery 100A of the second embodiment, temperature unevenness of the wound electrode body 110 can be suppressed, and as a result, charge / discharge reaction unevenness can be suppressed.

  Here, the welding process of the negative electrode current collector terminal 192A in the lithium ion secondary battery 100A will be described. The welding process of the positive electrode current collector terminal 191A is the same as that of the negative electrode current collector terminal 192A. Further, other manufacturing steps in the lithium ion secondary battery 100A are the same as those of the lithium ion secondary battery 100 of the first embodiment.

  In the welding process of the negative electrode current collector terminal 192A, first, two current collector connection portions 194 and 194 having a flat plate shape are inserted into a space located at the center of the wound negative electrode current collector laminated portion 126A. In other words, it is inserted between the front negative electrode current collector stack portion 126Aa and the rear negative electrode current collector stack portion 126Ab. Subsequently, as shown in FIG. 9, one current collector connecting portion 194 is joined to the front negative electrode current collector laminated portion 126Aa by resistance welding. Thereafter, the other current collector connection portion 194 is joined to the rear negative electrode current collector laminated portion 126Ab by resistance welding.

  Here, the resistance welding machine used for resistance welding includes the laminated portion side electrode 30A and the terminal side electrode 20A, and the contact surface 31A of the laminated portion side electrode 30A is formed with irregularities by electric discharge machining. The irregularities are formed concentrically as in the first embodiment. The degree of unevenness is about 15 μm to 20 μm in terms of the maximum roughness Rmax. This is rougher than the surface roughness of the laminate side electrode of the resistance welding machine used conventionally. In the second embodiment, the thickness of the negative electrode current collector laminated portion 126A sandwiched between a pair of resistance welding electrodes during resistance welding is divided by the amount of the negative electrode current collector laminated portion 126A divided into two. It is thinner than the negative electrode current collector lamination portion 126 of the first embodiment. Therefore, the surface roughness of the unevenness formed on the stacked portion side electrode 30A is made lower than that in the first embodiment. Depending on the thickness of the divided negative electrode current collector laminated portion 126A, the surface roughness of the unevenness formed on the laminated portion side electrode 30A may be lowered to about Rmax 10 μm.

  When resistance welding is performed using such a resistance welder, as shown in FIG. 10, the welding positions of the front negative electrode current collector stack portion 126 </ b> Aa and the rear negative electrode current collector stack portion 126 </ b> Ab are in close contact with each other. As a result of improved weldability and good welding, it protrudes inward. The unevenness applied to the contact surface 31A of the laminated portion side electrode 30A is transferred to each welding mark 127A of the front negative electrode current collector laminated portion 126Aa and the rear negative electrode current collector laminated portion 126Ab. The surface roughness of the weld mark 127A is about 9 μm to 15 μm in terms of the maximum roughness Rmax.

  Also in the second embodiment described above, the same effects as in the first embodiment are exhibited.

(Other changes)
As mentioned above, although this invention was demonstrated according to embodiment, it cannot be overemphasized that this invention is not limited to the above-mentioned embodiment, It can change suitably and apply in the range which does not deviate from the summary. For example, in the above embodiment, a lithium ion secondary battery is exemplified as the secondary battery. However, the technical idea of the present invention can be applied to other types of secondary batteries such as a nickel hydride secondary battery. .

  In the embodiment, the current collecting terminals 191 and 192 include the external terminal portions 191a and 192a, but may not include the external terminal portions 191a and 192a. In other words, a current collecting terminal disposed inside the battery case 180 is provided separately from the external terminal portion exposed to the outside of the battery case 180, and the external terminal portion and the current collecting terminal are provided inside or outside the battery case. May be electrically joined.

  In the embodiment, the negative electrode current collector terminal 192 is welded by resistance welding and the positive electrode current collector terminal 191 is welded by ultrasonic welding. However, the positive electrode current collector terminal 191 is welded to the positive electrode current collector laminated portion 136 by resistance welding. May be. Also in this case, by performing resistance welding using a material whose surface roughness of the contact surface 31 of the laminated portion side electrode 30 is rougher than the conventional one as shown in FIG. 3 and FIG. Similarly, welding can be performed better than before.

  In the embodiment, the contact surface of the laminated portion side electrode 30 has concentric irregularities (see FIG. 4) by electric discharge machining. However, if the irregularities to be applied are regular, a lattice shape or a stripe shape is used. Other irregularities may be used. The stripe shape may be vertical, horizontal, or diagonal.

20 ... Terminal side electrode 30 ... Laminate side electrode 31 ... Contact surface 100 ... Battery (non-electrolyte secondary battery)
DESCRIPTION OF SYMBOLS 110 ... Winding electrode body 120 ... Negative electrode plate 121 ... Negative electrode collector 121b ... Negative electrode active material layer non-formation part 122 ... Negative electrode active material layer 126 ... Negative electrode collector laminated part 127 ... Weld trace 130 ... Positive electrode plate 131 ... Positive electrode Current collector 131b ... Positive electrode active material layer non-forming part 132 ... Positive electrode active material layer 136 ... Positive electrode current collector laminated part 150 ... Separator 191 ... Positive electrode current collector terminal 192 ... Negative electrode current collector terminal

Claims (5)

A positive electrode plate with a positive electrode active material layer formed on the surface of a foil-shaped positive electrode current collector and a negative electrode plate with a negative electrode active material layer formed on the surface of a foil-shaped negative electrode current collector are wound together with a separator. Thus, a positive electrode collector in which a positive electrode active material layer non-formed portion where the positive electrode active material layer is not formed protrudes from the negative electrode plate at one end of both ends in the winding axis direction. A negative electrode having an electric body laminated portion and laminated with a negative electrode active material layer non-formed portion in which the negative electrode active material layer is not formed protruding from the positive electrode plate at the other end of the both end portions Producing a wound electrode body having a current collector laminate;
Disposing a current collector terminal of a corresponding electrode on a current collector laminate of at least one of the positive electrode current collector laminate or the negative electrode current collector laminate; and
A terminal electrode for resistance welding is brought into contact with the current collector terminal arranged in the current collector laminated portion, and a pair of the terminal side electrode is laminated on the current collector laminated portion in which the current collector terminal is arranged. A step of sandwiching the current collector terminal and the current collector laminated portion by contacting a portion side electrode;
A step of performing resistance welding while applying a pressing force between the terminal side electrode and the laminated portion side electrode, and a method of manufacturing a secondary battery,
The laminated part side electrode is characterized in that the contact surface with the current collector laminated part is an irregular surface having a regular irregular shape with a maximum roughness (Rmax) of 15 μm to 25 μm. A method for manufacturing a secondary battery. A method of manufacturing a secondary battery according to claim 1,
The pressing force applied between the terminal side electrode and the laminated portion side electrode, as a ^pressure, a manufacturing method of a secondary battery, which is a ^{142N / mm 2 ~424N / mm 2} . A method of manufacturing a secondary battery according to claim 1 or claim 2,
The regular uneven shape of the contact surface is a shape in which a plurality of concentric circles are formed at predetermined intervals from the center of the contact surface toward the outside. Method. A method for manufacturing a secondary battery according to any one of claims 1 to 3,
The method for manufacturing a secondary battery, wherein the regular uneven shape of the contact surface is formed by electric discharge machining. A positive electrode plate having a positive electrode active material layer formed on the surface of a foil-like positive electrode current collector and a negative electrode plate having a negative electrode active material layer formed on the surface of a foil-like negative electrode current collector are wound together with a separator. A wound electrode body,
A positive and negative current collector terminal joined to the wound electrode body, and a secondary battery comprising:
One end of both ends in the winding axis direction of the wound electrode body is laminated in a state where the positive electrode active material layer non-formed portion where the positive electrode active material layer is not formed protrudes from the negative electrode plate. A positive electrode current collector laminate,
The other end of the both end portions is a negative electrode current collector laminated portion laminated in a state where the negative electrode active material layer non-formed portion where the negative electrode active material layer is not formed protrudes from the positive electrode plate,
The current collector laminated portion of at least one of the positive electrode current collector laminated portion or the negative electrode current collector laminated portion is joined to the current collecting terminal by resistance welding,
The welding mark formed on the surface of the current collector laminated portion by the resistance welding has a regular uneven shape having a maximum surface roughness (Rmax) of 9 μm to 25 μm. battery.