JP2019032985A - Non-aqueous electrolyte secondary battery and manufacturing method of battery pack - Google Patents

Abstract

To surely weld a negative electrode tab made of a copper or a copper alloy to a negative terminal.SOLUTION: In a manufacturing method of a non-aqueous electrolyte secondary battery, according to an embodiment, one surface of a negative electrode tab made of any one of a copper and a copper alloy connected to a negative plate is contacted to a negative terminal, and the other surface of the negative electrode tab is contacted to a metal in which the other surface of the negative electrode tab contains a metal which has an electric resistance larger than that of the copper as a main component, and in such a state, the negative electrode tab, the negative terminal, and the metal plate are alternately welded. The metal plate preferably contains one of nickel and iron as a main component.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a non-aqueous electrolyte secondary battery using a negative electrode tab made of copper or a copper alloy and a method for manufacturing a battery pack.

  In recent years, with the enhancement of functions of thin electronic devices such as smartphones and tablets, non-aqueous electrolyte secondary batteries used as their drive power sources are also required to have a thinner and higher capacity. Nonaqueous electrolyte secondary batteries are also widely used in applications such as electric tools and electric assist bicycles, and high output is required.

  The electrode plate used in the nonaqueous electrolyte secondary battery is prepared by applying a mixture slurry containing an active material on a metal foil as a core, and a core in which a mixture slurry is not applied to a part of the electrode plate A body exposed portion is provided. A current collecting tab is connected to the core exposed portion, and the current collecting tab forms a current path between the electrode plate and the external terminal. For the core, a metal foil that can exist stably even when exposed to the potential of the positive electrode or the negative electrode in a non-aqueous electrolyte is used. Therefore, an aluminum foil is preferably used for the positive electrode core, and a copper foil is preferably used for the negative electrode core.

  In a rectangular nonaqueous electrolyte secondary battery, a bottomed cylindrical outer can made of aluminum is used as the outer casing, and an aluminum plate is used as the sealing plate. The sealing plate is attached to the opening of the outer can by laser welding. Since the positive electrode tab connected to the positive electrode plate is joined to the sealing plate, the sealing plate and the outer can can be used as the positive electrode terminal. On the other hand, the negative electrode terminal is attached to a through hole provided in the sealing plate while being insulated from the periphery thereof, and a negative electrode tab connected to the negative electrode plate is joined to the negative electrode terminal.

  In order to reduce the internal resistance of the nonaqueous electrolyte secondary battery, it is preferable to use a material with low electrical resistance for the current collecting tab. Patent Document 1 discloses a current collecting tab for a battery having a three-layer structure using nickel or iron as a main component as a surface layer and copper or a copper alloy as an intermediate layer. Patent Document 2 discloses that a current collecting tab having a three-layer structure using nickel as a surface layer and copper as an intermediate layer is used as a wiring material for a battery pack.

JP 11-297300 A JP 2004-192891 A Japanese Patent Laid-Open No. 11-283607

  The copper tab which has copper as a main component has the subject that welding with metal members, such as a negative electrode terminal, is difficult. As disclosed in Patent Document 1 or 2, the welding problem is solved by using a clad material in which the surface of a copper layer is laminated with a nickel layer as a current collecting tab. However, such a three-layer clad material has a higher electrical resistance than a copper tab. Therefore, since a copper tab is used, it is desired to improve weldability with a metal member such as a negative electrode terminal of the copper tab.

Patent Document 3 discloses a method of resistance welding a positive electrode tab of a cylindrical battery and a valve cap of a sealing body. Patent Document 3 presents a solution to the problem that it is difficult to generate heat necessary for resistance welding because the electrical resistance of aluminum is low when metal members made of aluminum are resistance-welded. . Specifically, a method of performing resistance welding with a positive electrode tab and a valve cap overlapped and a welding member made of a conductive material having a higher electric resistance than aluminum interposed between the welding rod and the positive electrode tab is disclosed. Has been.

  According to the welding method disclosed in Patent Document 3, aluminum can be reliably welded to each other by resistance welding. However, the welding method is intended for resistance welding of aluminum having a low melting point, and is not intended for welding between metals having a high melting point such as copper, iron, and nickel.

  In order to solve the above-described problem, a method for manufacturing a nonaqueous electrolyte secondary battery according to one embodiment of the present invention includes using one surface of a negative electrode tab made of copper or a copper alloy connected to a negative electrode plate as a negative electrode terminal. The negative electrode terminal, the negative electrode tab, and the metal plate are welded to each other with the other surface of the negative electrode tab in contact with a metal plate mainly composed of a metal having a higher electrical resistance than copper. A non-aqueous electrolyte secondary battery manufactured by such a manufacturing method includes an electrode body in which a positive electrode plate and a negative electrode plate are wound or stacked with a separator interposed therebetween, a non-aqueous electrolyte, and the electrode body and the non-aqueous electrolyte. A bottomed cylindrical outer can and a sealing plate for sealing the opening of the outer can.

  Further, in the above method for producing a non-aqueous electrolyte secondary battery, a negative electrode tab made of either copper or a copper alloy led out from the exterior body of the non-aqueous electrolyte secondary battery is welded to the negative electrode current collector of the protective circuit board. The present invention can also be applied to a method for manufacturing a battery pack. That is, in the battery pack manufacturing method according to one aspect of the present invention, one surface of the negative electrode tab derived from the exterior body of the nonaqueous electrolyte secondary battery is brought into contact with the negative electrode current collector of the protective circuit board, The negative electrode current collector, the negative electrode tab, and the metal plate are welded to each other in a state where a metal plate mainly composed of a metal having a higher electrical resistance than copper is in contact with the other surface.

  According to one aspect of the present invention, a negative electrode tab made of copper or a copper alloy can be reliably welded to a negative electrode terminal or a negative electrode current collector of a protective circuit board to ensure sufficient welding strength. As a result, since it becomes possible to use copper or a copper alloy having a low electrical resistance for the negative electrode tab, the internal resistance of the nonaqueous electrolyte secondary battery or the battery pack can be reduced.

It is a perspective view of a square nonaqueous electrolyte secondary battery. It is a schematic diagram which shows the connection method of a positive electrode tab and a negative electrode tab, and an external terminal. It is a schematic diagram which shows the laser welding of a negative electrode tab and a negative electrode terminal. It is a schematic diagram which shows resistance welding of a negative electrode tab and a negative electrode terminal. It is a schematic diagram of the battery pack which shows the connection method of a battery and a protection circuit board.

  Hereinafter, although the form for implementing this invention is demonstrated, this invention is not limited to the following embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  FIG. 1 shows a prismatic nonaqueous electrolyte secondary battery 10 according to an embodiment of the present invention. An electrode body 17 and a non-aqueous electrolyte are accommodated in a bottomed cylindrical rectangular outer can 19, and an opening of the outer can 19 is sealed with a sealing plate 11. As shown in FIG. 2, the negative electrode tab 15 connected to the negative electrode plate and the positive electrode tab 16 connected to the positive electrode plate are led out from the same end surface of the electrode body 17. The negative electrode tab 15 is welded to the negative electrode terminal 12 press-fitted and fixed to the through hole of the sealing plate 11 via the insulating member 13, and the positive electrode tab 16 is welded to the inner surface of the sealing plate 11. Therefore, the sealing plate 11 and the outer can 19 can function as a positive electrode terminal.

  The negative electrode plate has a negative electrode core and a negative electrode mixture layer formed on the negative electrode core. The negative electrode mixture layer can be formed, for example, by applying a negative electrode mixture slurry prepared by kneading a negative electrode active material, a binder, and a thickener in a dispersion medium onto a negative electrode core and drying it. . The negative electrode plate is provided with a negative electrode core exposed portion for connecting the negative electrode tab 15. The negative electrode core exposed portion can be easily formed by intermittently applying the negative electrode mixture slurry onto the negative electrode core.

  Copper or a copper alloy is used for the negative electrode tab 15. The copper alloy is preferably composed mainly of copper, and the copper content is more preferably 90% by mass or more. By using the negative electrode tab made of copper or a copper alloy, the electrical resistance of the negative electrode tab 15 is reduced, and the load characteristics of the nonaqueous electrolyte secondary battery are improved.

  As the negative electrode core, it is preferable to use a metal foil that can exist stably even when exposed to a negative electrode potential in a non-aqueous electrolyte, and like the negative electrode tab 15, it is preferable to use a metal foil of copper or a copper alloy. Although the connection method in particular of the negative electrode tab 15 to the negative electrode core is not restrict | limited, Ultrasonic welding, resistance welding, and laser welding are illustrated.

  The negative electrode active material can be appropriately selected from materials capable of reversibly occluding and releasing lithium ions. For example, carbon materials such as artificial graphite and natural graphite, and silicon materials such as silicon and silicon oxide can be used. These can be used alone or in combination of two or more.

  The positive electrode plate has a positive electrode core body and a positive electrode mixture layer formed on the positive electrode core body. The positive electrode mixture layer can be formed, for example, by applying a positive electrode mixture slurry prepared by kneading a positive electrode active material, a binder, and a conductive agent in a dispersion medium onto a positive electrode core and drying it. A positive electrode core exposed portion for connecting the positive electrode tab 16 is provided on the positive electrode plate. The positive electrode core exposed portion can be easily formed by intermittently applying the positive electrode mixture slurry onto the positive electrode core.

  For the positive electrode core, it is preferable to use a metal foil that can exist stably even when exposed to a positive electrode potential in a non-aqueous electrolyte, and it is preferable to use aluminum or an aluminum alloy as a constituent material of the metal foil. Aluminum or an aluminum alloy is preferably used for the positive electrode tab 16 connected to the positive electrode core. Although the connection method in particular of the positive electrode tab 16 to the positive electrode core is not restrict | limited, Ultrasonic welding, resistance welding, and laser welding are illustrated.

The positive electrode active material can be appropriately selected from materials capable of reversibly occluding and releasing lithium ions. For example, a lithium transition metal composite oxide represented by LiMO ₂ (M is at least one of Co, Ni, and Mn), LiMn ₂ O ₄ , LiFePO ₄ , and the like can be used. These can be used alone or in combination of two or more. Moreover, these positive electrode active materials can also be used by adding at least one of zirconium, magnesium, aluminum, and titanium, or by replacing with a transition metal element.

  The electrode body 17 can be produced by winding a negative electrode plate and a positive electrode plate in a flat shape via a separator. The negative electrode tab 15 and the positive electrode tab 16 are led out from the same end face of the electrode body, and are welded to the negative electrode terminal 12 and the sealing plate 11 as the positive electrode terminal, respectively. Aluminum is used for the sealing plate 11, and the positive electrode tab 16 can be welded to the sealing plate 11 by laser welding. Iron, nickel, and stainless steel can be used for the negative electrode terminal 12. When iron is used, the surface is preferably plated with nickel.

As the separator, a microporous film mainly composed of polyolefin such as polyethylene (PE) or polypropylene (PP) can be used. The microporous membrane can be used singly or as a laminate of two or more layers. In a laminated separator having two or more layers, it is preferable to use a layer mainly composed of polyethylene (PE) having a low melting point as an intermediate layer and polypropylene (PP) excellent in oxidation resistance as a surface layer. Furthermore, inorganic particles such as aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and silicon oxide (SiO ₂ ) can be added to the separator. Such inorganic particles can be carried in the separator and can be applied together with a binder on the separator surface.

  The electrode body 17 can be produced by winding a positive electrode plate and a negative electrode plate in a circular shape or a flat shape with a separator interposed therebetween. The electrode body obtained by winding in a circle is pressed into a flat shape. An electrode body produced by laminating a positive electrode plate and a negative electrode plate with a separator interposed therebetween can also be used.

  In this embodiment, the rectangular outer can 19 is used, but a cylindrical outer can can also be used. Examples of the constituent material of the outer can include aluminum, iron, nickel, and stainless steel. When the outer can is exposed to the positive electrode potential, it is preferable to use aluminum or an aluminum alloy. When the outer can is exposed to the positive electrode potential as in this embodiment, it is preferable to use aluminum or an aluminum alloy.

  Here, the welding method of the negative electrode tab 15 and the negative electrode terminal 12 is demonstrated. As a method for welding the negative electrode tab 15 and the negative electrode terminal 12, laser welding and resistance welding are exemplified.

  First, the case where laser welding is used will be described. As shown in FIG. 3, one surface of the negative electrode tab 15 is in contact with the negative electrode terminal 12, and the other surface of the negative electrode tab 15 is in contact with a metal plate 18 whose main component is a metal having a larger electrical resistance than copper. Thus, laser welding is performed by irradiating the surface of the metal plate 18 with laser light. Irradiation heat by laser light is generated in the metal plate 18, and the negative electrode tab 15 is welded to the negative electrode terminal 12 in the process of transmitting the irradiation heat to the negative electrode tab 15 and the negative electrode terminal 12.

  The thermal conductivity and the reflectance of the laser beam of the metal plate 18 whose main component is a metal having a larger electric resistance than copper are lower than those of a negative electrode tab made of copper or a copper alloy. Therefore, when the metal plate 18 is irradiated with laser light, the heat of irradiation is generated with higher efficiency with respect to the output of the laser than when the laser light is irradiated onto the negative electrode tab 15. Further, since the surface of the negative electrode tab 15 is in contact with the heated metal plate 18, the irradiation heat transmitted from the metal plate 18 to the negative electrode tab 15 is not easily radiated. Therefore, the negative electrode tab 15 and the negative electrode terminal 12 are reliably welded.

Examples of lasers used for laser welding include YAG laser, CO ₂ laser, excimer laser, and fiber laser. Among these, the fiber laser is excellent in the laser beam condensing property, and is suitable for welding the negative electrode tab 15 and the negative electrode terminal 12 made of copper or a copper alloy.

  Next, the case where resistance welding is used will be described. As shown in FIG. 4, one surface of the negative electrode tab 15 is in contact with the negative electrode terminal 12, and the other surface of the negative electrode tab 15 is in contact with a metal plate 18 whose main component is a metal having a higher electrical resistance than copper. Thus, resistance welding is performed by flowing a predetermined current between the first electrode rod 41 and the second electrode rod 42. By passing a current between the first electrode rod 41 and the second electrode rod 42, Joule heat is generated in each of the metal plate 18, the negative electrode tab 15, and the negative electrode terminal 12. Compared with the case where only the negative electrode tab 15 and the negative electrode terminal 12 are resistance welded, the negative electrode is used when resistance welding is performed using the metal plate 18 to the extent that Joule heat generated in the metal plate 18 is transmitted to the negative electrode tab 15 and the negative electrode terminal 12. The welding of the tab 15 and the negative electrode terminal 12 becomes easy.

  During resistance welding, current flows through the metal plate 18, the negative electrode tab 15, and the negative electrode terminal 12, but when the current flows in a wide range, Joule heat is not effectively generated. Therefore, when performing resistance welding, in order to reduce the contact area of the contact surface of the negative electrode tab 15 and the negative electrode terminal 12, it is preferable to provide a protrusion on at least one surface thereof. In addition, the metal plate 18 is preferably disposed within the range of the contact surface between the negative electrode tab 15 and the negative electrode terminal 12 when viewed from the stacking direction of the negative electrode tab 15 and the negative electrode terminal 12. In this way, reactive current that does not contribute to resistance welding can be reduced.

  As described with reference to the examples of laser welding and resistance welding, one surface of the negative electrode tab 15 is brought into contact with the negative electrode terminal 12, and the other surface of the negative electrode tab 15 is mainly composed of a metal having a higher electric resistance than copper. The metal plate 18, the negative electrode tab 15, and the negative electrode terminal 12 are welded together while being in contact with the metal plate 18, thereby contributing the heat generated in the metal plate 18 to the welding of the negative electrode tab 15 and the negative electrode terminal 12. Can do. This makes it possible to reliably weld the negative electrode tab 15 made of copper or a copper alloy to the negative electrode terminal 12. Although the metal plate 18 is welded to the negative electrode tab 15, the metal plate 18 may be removed from the negative electrode tab 15 before the opening of the outer can 19 is sealed with the sealing plate 11.

  Since the shape of the metal plate is brought into contact with the negative electrode tab, the surface is preferably flat. However, the shape of the metal plate can be modified, for example, by providing an opening or unevenness in a part thereof as long as the effect of the present invention is not lost. The thickness of the metal plate is preferably 0.01 mm or more and 0.2 mm or less from the viewpoint of the amount of heat generated during welding of the metal plate and the prevention of damage. In the case of laser welding, the thickness of the metal plate is more preferably 0.05 mm or more and 0.15 mm or less. In the case of resistance welding, the thickness of the metal plate is more preferably 0.01 mm or more and 0.1 mm or less. The metal plate is preferably disposed on the negative electrode tab within a range that does not hinder the bending of the negative electrode tab.

  In laser welding, the heating value of the metal plate and the welding strength of the negative electrode tab and the negative electrode terminal can be controlled by adjusting the output value of the laser beam, so the degree of freedom of the metal plate material and dimensions, and the negative electrode tab size Is expensive. Furthermore, it is possible to reduce the thermal effect on the electrode body and the insulating plate disposed on the electrode body when the negative electrode tab and the negative electrode terminal are welded. Therefore, in the method for manufacturing a nonaqueous electrolyte secondary battery according to the present disclosure, it is preferable to use laser welding for welding the negative electrode tab and the negative electrode terminal.

  The sealing plate 11 to which the negative electrode tab 15 and the positive electrode tab 16 are connected is welded to the opening of the outer can 19 by laser welding. A liquid injection hole 14 is provided in the sealing plate 11, and a non-aqueous electrolyte is injected into the exterior can 19 through the liquid injection hole 14. After injecting the non-aqueous electrolyte, the injection hole 14 is closed with the same metal material as the sealing plate 11 to seal the inside of the battery.

  As the non-aqueous solvent that can be used for the non-aqueous electrolyte, cyclic carbonates, chain carbonates, cyclic carboxylic acid esters, and chain carboxylic acid esters can be used, and these should be used in combination of two or more. Is preferred. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). In addition, a cyclic carbonate in which part of hydrogen is substituted with fluorine, such as fluoroethylene carbonate (FEC), can also be used. Examples of the chain carbonate include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methyl propyl carbonate (MPC). Examples of cyclic carboxylic acid esters include γ-butyrolactone (γ-BL) and γ-valerolactone (γ-VL). Examples of chain carboxylic acid esters include methyl pivalate, ethyl pivalate, methyl isobutyrate, and methyl Pionate is exemplified.

LiPF ₆ , LiBF as lithium salts that can be used for the electrolyte salt of the non-aqueous electrolyte
₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiAsF ₆ , LiClO ₄ , Li ₂ B ₁₀ Cl ₁₀ and Li ₂ B ₁₂ Cl ₁₂ are exemplified. Among these, LiPF ₆ is particularly preferable, and the concentration in the nonaqueous electrolytic solution is preferably 0.5 to 2.0 mol / L. Other lithium salts such as LiBF ₄ may be mixed with LiPF ₆ .

  In the above embodiment, the method for welding the negative electrode tab and the negative electrode terminal inside the battery has been described. Some non-aqueous electrolyte secondary batteries have a structure in which a negative electrode tab or a positive electrode tab is led out of the battery through an exterior body. In the nonaqueous electrolyte secondary battery having such a structure, the negative electrode tab and the positive electrode tab function as a negative electrode terminal and a positive electrode terminal, respectively. Therefore, welding of the negative electrode tab and the negative electrode terminal is unnecessary. However, when the negative electrode tab and the positive electrode tab are used as the negative electrode terminal and the positive electrode terminal, respectively, the negative electrode tab and the positive electrode tab may be welded to the negative electrode current collector and the positive electrode current collector of the protection circuit board, respectively, to form a battery pack. . When copper or a copper alloy is used for the negative electrode tab, the welding method described in the above embodiment can be applied to the welding of the negative electrode tab and the negative electrode current collector of the protective circuit board.

  As an example of a non-aqueous electrolyte secondary battery in which a negative electrode tab or a positive electrode tab connected to the electrode body is led out of the battery, a pouch-type non-aqueous electrolyte secondary battery 51 shown in FIG. A laminated sheet obtained by laminating a resin sheet such as polypropylene or nylon and an aluminum sheet is used for the exterior body 52 of the pouch-type nonaqueous electrolyte secondary battery 51. A pouch-shaped exterior body 52 that accommodates the electrode body and the non-aqueous electrolyte is formed by overlapping two laminate sheets or by folding one laminate sheet in two. The negative electrode tab 15 and the positive electrode tab 16 are led out of the battery from between the overlapping portions of the laminate sheet. The negative electrode tab 15 and the positive electrode tab 16 are welded to the negative electrode current collector 55 and the positive electrode current collector 56 of the protection circuit board 54, respectively. Thus, the battery pack 50 is configured by integrating the pouch-type nonaqueous electrolyte secondary battery 51 and the protection circuit board 54. The protective circuit board 54 connected to the pouch-type nonaqueous electrolyte secondary battery 51 is disposed on the terrace 53 by bending the negative electrode tab 15 and the positive electrode tab 16. Thereby, the occupied volume of the battery pack 50 can be reduced.

  The negative electrode current collector 55 is preferably made of nickel, iron, or stainless steel. When using iron, it is preferable to nickel-plat the surface. The welding method of the negative electrode tab 15 and the negative electrode current collector 55 is understood by replacing the negative electrode terminal 12 with the negative electrode current collector 55 in each of FIGS. 3 and 4.

  The positive electrode current collector 56 is preferably made of aluminum or an aluminum alloy. As a method for welding the positive electrode tab 16 and the positive electrode current collector 56, laser welding and ultrasonic welding are exemplified.

Example 1
A flat electrode body was prepared using a negative electrode plate to which a copper negative electrode tab was connected, and the electrode body was housed in a bottomed cylindrical aluminum outer can. The thickness of the negative electrode tab was 0.1 mm, and the width was 3 mm. A negative electrode terminal made of nickel-plated iron is press-fitted and fixed to an aluminum sealing plate for sealing the outer can through an insulating member. The negative electrode tab led out from the electrode body housed in the outer can is brought into contact with the negative electrode terminal, and further, as shown in FIG. 3, a nickel metal plate is brought into contact with the negative electrode tab, and the metal plate is irradiated with laser light. The negative electrode tab and the negative electrode terminal were welded together. The planar shape of the metal plate was a square with a side of 2.5 mm, and its thickness was 0.1 mm. Laser welding was performed by irradiating a metal plate with two laser beams having an energy of 6.5 J. The welding area of the negative electrode tab and the negative electrode terminal was 0.6 mm ² . The positive electrode tab was welded to the inner surface of the sealing body by laser welding. The sealing plate to which the negative electrode tab and the positive electrode tab were welded was welded to the opening of the outer can by laser welding, and then a nonaqueous electrolyte was injected from the injection hole of the sealing plate. Finally, the liquid injection hole was sealed with an aluminum plate to produce a rectangular nonaqueous electrolyte secondary battery according to Example 1 having a thickness of 5.5 mm, a width of 51 mm, and a height of 72 mm.

(Example 2)
A square nonaqueous electrolyte secondary battery according to Example 2 was produced in the same manner as in Example 1 except that the negative electrode tab and the negative electrode terminal were welded by resistance welding. As shown in FIG. 4, the resistance welding of the negative electrode tab and the negative electrode terminal is performed by contacting the first electrode rod and the second electrode rod with the negative electrode tab in contact with the negative electrode terminal and further with the nickel metal plate in contact with the negative electrode tab. During this time, a current of 1.6 kA was passed. During resistance welding, a load of 3 kg was applied to each of the first electrode rod and the second electrode rod.

(Comparative Example 1)
Other than using a negative electrode tab made of a copper-nickel (Cu-Ni) clad material instead of a copper negative electrode tab and welding the negative electrode tab and the negative electrode terminal by laser welding without using a nickel metal plate Produced a square nonaqueous electrolyte secondary battery according to Comparative Example 1 in the same manner as in Example 1.

(Confirmation of welding strength between negative electrode tab and negative electrode terminal)
For each of the batteries of Examples 1 and 2 and Comparative Example 1, a tensile test of the negative electrode tab was performed until the welded portion of the negative electrode tab and the negative electrode terminal or the negative electrode tab broke with the sealing plate fixed. In any battery, since the negative electrode tab, not the welded portion, was broken, it was confirmed that the welded portion formed between the negative electrode tab and the negative electrode terminal had sufficient weld strength. In Example 1, when the negative electrode tab was irradiated with laser light without using a nickel metal plate, it was confirmed that welding of the negative electrode tab and the negative electrode terminal was impossible. From this, it can be seen that the present disclosure exhibits an advantageous effect when a copper negative electrode tab is welded to the negative electrode terminal. Even when a copper alloy negative electrode tab is used instead of the copper negative electrode tab, the same effect is expected to be exhibited.

(Vibration test)
Each battery of Examples 1 and 2 and Comparative Example 1 was sandwiched and fixed between two acrylic plates (thickness 5 mm, width 60 mm, height 80 mm) to produce a simulated battery pack for vibration test. The simulated battery pack was placed in a box made of an acrylic plate (a cube having a side of 150 mm), and a vibration test was performed by applying vibration having a frequency of 8 Hz and an amplitude of 50 mm for 60 minutes. After the test, the simulated battery pack was disassembled to confirm whether the negative electrode tab was broken. For the vibration test, 10 batteries of Examples 1 and 2 and Comparative Example were used. The results are shown in Table 1.

As a result of the vibration test, breakage of the negative electrode tab was observed in a part of the batteries of the comparative example, but breakage of the negative electrode tab was not observed in all the batteries of Examples 1 and 2. Since Cu-Ni clad material is bonded with dissimilar metals, if stress such as vibration is applied to the negative electrode tab made of clad material, cracks are likely to occur due to the difference in elongation of each layer. Conceivable. On the other hand, the negative electrode tabs of Examples 1 and 2 have a nickel metal plate welded to the surface, but the metal plate is not welded to the entire surface of the negative electrode tab. Therefore, even if stress such as vibration is applied to the negative electrode tab, the stress received by the metal plate is small, and thus cracking of the negative electrode tab is prevented as in the case of using a clad material.

  Moreover, the thickness of the negative electrode tab of Example 1 and 2 is the same as the thickness of the negative electrode tab of a comparative example. Therefore, compared with the comparative example, in Examples 1 and 2, since the internal resistance of the battery is reduced, advantageous effects are exhibited in terms of battery characteristics such as improvement in load characteristics and reduction in the amount of heat generated during an external short circuit.

  In Examples 1 and 2, a nickel metal plate is welded to the negative electrode tab. Therefore, the negative electrode tab of each Example is apparently similar to the negative electrode tab made of the Cu—Ni clad material of the comparative example. However, as described above, according to the present disclosure, it is possible to provide a nonaqueous electrolyte secondary battery that is more excellent in reliability and battery characteristics than the case where a negative electrode tab made of a Cu—Ni clad material is used.

  According to the present invention, a negative electrode tab made of copper or a copper alloy can be reliably welded to the negative electrode terminal or the negative electrode current collector of the protective circuit board to ensure sufficient welding strength. Thus, since it becomes possible to use copper or a copper alloy with low electrical resistance for the negative electrode tab, the internal resistance of the nonaqueous electrolyte secondary battery or the battery pack can be reduced. Therefore, the industrial applicability of the present invention is great.

DESCRIPTION OF SYMBOLS 10 Square nonaqueous electrolyte secondary battery 11 Sealing plate 12 Negative electrode terminal 13 Insulating member 14 Injection hole 15 Negative electrode tab 16 Positive electrode tab 17 Electrode body 18 Metal plate 19 Exterior can 41 First electrode rod 42 Second electrode rod 50 Battery pack 51 Pouch Type Nonaqueous Electrolyte Secondary Battery 52 Exterior Body 53 Terrace 54 Protective Circuit Board 55 Negative Electrode Current Collector 56 Positive Electrode Current Collector

Claims (10)

An electrode body in which a positive electrode plate and a negative electrode plate are wound or laminated with a separator interposed therebetween, a nonaqueous electrolyte, a bottomed cylindrical outer can that contains the electrode body and the nonaqueous electrolyte, and an opening of the outer can A non-aqueous electrolyte secondary battery having a negative electrode tab connected to the negative electrode plate and a negative electrode terminal fixed in a state of being insulated from the sealing plate. ,
The negative electrode tab is made of one of copper and copper alloy,
In the state where one surface of the negative electrode tab is in contact with the negative electrode terminal and the other surface of the negative electrode tab is in contact with a metal plate whose main component is a metal having a higher electrical resistance than copper, the negative electrode tab and the negative electrode A method of manufacturing a non-aqueous electrolyte secondary battery, wherein the terminal and the metal plate are welded together.   The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein the metal plate is irradiated with laser light to weld the negative electrode tab, the negative electrode terminal, and the metal plate.   2. The resistance welding of the negative electrode tab, the negative electrode terminal, and the metal plate is performed by bringing a first welding rod into contact with the metal plate and bringing a second welding rod into contact with a battery inner surface of the negative electrode terminal. The manufacturing method of the nonaqueous electrolyte secondary battery as described.   The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein a main component of the metal plate is one of nickel and iron.   The method for manufacturing a nonaqueous electrolyte secondary battery according to claim 1, wherein the metal plate is disposed within a range of a contact surface between the negative electrode tab and the negative electrode terminal.   The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein a main component of the negative electrode terminal is one of nickel and iron. A non-aqueous electrolyte secondary battery in which a negative electrode tab made of one of copper and a copper alloy is led out of the battery through an exterior body, and a manufacturing method of a battery pack including a protective circuit board,
With one surface of the negative electrode tab in contact with the negative electrode current collector of the protection circuit board, the other surface of the negative electrode tab is in contact with a metal plate whose main component is a metal having a larger electrical resistance than copper, The method of manufacturing a battery pack, wherein the negative electrode tab, the negative electrode current collector, and the metal plate are welded together.   The method for manufacturing a battery pack according to claim 7, wherein the metal plate is irradiated with laser light to weld the negative electrode tab, the negative electrode current collector, and the metal plate.   8. The resistance welding of the negative electrode tab, the negative electrode current collector, and the metal plate is performed by bringing a first welding rod into contact with the metal plate and bringing a second welding rod into contact with the negative electrode current collector. The manufacturing method of the battery pack of description.   The method for manufacturing a battery pack according to claim 7, wherein a main component of the metal plate is one of nickel and iron.

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