JP5985993B2 - Battery pack and manufacturing method thereof - Google Patents

Description

The present invention relates to an assembled battery and a manufacturing method thereof , for example, an assembled battery mounted on a vehicle or the like and a manufacturing method thereof .

  2. Description of the Related Art Conventionally, a secondary battery having a large capacity has been developed as a power source for, for example, a hybrid electric vehicle or a pure electric vehicle. Among such secondary batteries, a rectangular lithium ion secondary battery is attracting attention as a secondary battery having a high energy density.

  A prismatic lithium ion secondary battery includes, for example, a flat battery element in which a positive electrode foil coated with a positive electrode active material, a negative electrode foil coated with a negative electrode active material, and a separator for insulating each of them are rolled up. Electrically connected to the positive external terminal and the negative external terminal provided on the battery lid, the storage element is accommodated in the battery can, and the opening of the battery can is welded and sealed with the battery lid. The electrolyte solution is injected from the liquid injection hole, and a liquid injection stopper is inserted into the liquid injection hole and welded and sealed by laser welding.

  And by arranging a plurality of prismatic lithium ion secondary batteries as described above, welding a bus bar to the external terminal of each battery, and connecting adjacent batteries via the bus bar, a plurality of secondary batteries are connected in series or An assembled battery connected in parallel is produced.

  By the way, when the formation material of the positive electrode external terminal and the negative electrode external terminal of the secondary battery is different, for example, when the positive electrode external terminal is made of aluminum and the negative electrode external terminal is made of copper, the external of the positive electrode is obtained when a copper bus bar is used. While it is difficult to weld the terminal and the bus bar, it is known that the use of an aluminum bus bar makes it difficult to weld the negative electrode external terminal and the bus bar.

  In order to solve such a problem, Patent Document 1 uses a cold spray method to accelerate a powder containing pure copper, a noble metal or an alloy of pure copper and a noble metal together with a gas, and contact the powder with a member to be joined. A conductive terminal is disclosed in which a metal film is formed on the surface of the contact portion by spraying and depositing it on the surface of the contact portion in the solid state.

JP 2012-144758 A

  However, in the conductive terminal disclosed in Patent Document 1, a metal film having high hardness and good conductivity can be formed on the contact portion surface of the conductive terminal for welding metal members to each other. No mention is made of what kind of structure should be adopted when such a metal film is formed on the bus bar surface of the assembled battery.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an assembled battery in which a bus bar is joined to an external terminal and a plurality of secondary batteries are connected via the bus bar. It is an object of the present invention to provide an assembled battery and a method for manufacturing the same that can improve the welding reliability with a terminal.

  In order to solve the above-described problems, an assembled battery according to the present invention is an assembled battery in which a plurality of secondary batteries having positive and negative external terminals are connected via a bus bar, and the outside of the secondary battery. Between at least one external terminal of the terminals and the bus bar, a metal powder made of a material different from the bus bar forming material and having excellent weldability with the external terminal forming material is deposited. And the connection layer and the bus bar are joined by metal bonding at the interface, and the connection layer and the external terminal are surfaces for reducing surface roughness. It is welded through the welded surface of the connection layer that has been processed.

  According to the present invention, in an assembled battery in which a bus bar is joined to an external terminal and a plurality of secondary batteries are connected via the bus bar, the external terminal and the bus bar are excellent in weldability with the external terminal forming material. The metal powder is joined via a connection layer formed by being deposited on the bus bar, and the connection layer and the external terminal are connected via a welded surface subjected to a surface processing treatment for reducing the surface roughness. Therefore, the welding reliability between the bus bar and the external terminal can be improved.

  Problems, means, and effects other than those described above will become apparent from the following description of embodiments.

1 is an overall perspective view showing an appearance of a battery pack according to Embodiment 1 of the present invention. The side view of the assembled battery shown in FIG. The perspective view which shows the external appearance of the bus bar of the assembled battery shown in FIG. FIG. 2 is a partially enlarged view schematically illustrating a process of forming a connection layer on a bus bar of the assembled battery illustrated in FIG. 1, and illustrating a process of depositing metal powder on the surface of the bus bar. FIG. 2 is a partially enlarged view schematically illustrating a process of forming a connection layer on a bus bar of the assembled battery illustrated in FIG. 1, and illustrating a state in which metal powder is deposited on the surface of the bus bar. It is the elements on larger scale explaining typically the process of forming a connection layer in the bus bar of the battery pack shown in Drawing 1, and explains the state where surface treatment was given to the surface of metal powder deposited on the surface of a bus bar FIG. The elements on larger scale explaining the process of welding a bus bar to a square secondary battery. The longitudinal cross-sectional view which expands and shows the welding location of a bus-bar and an external terminal. The longitudinal cross-sectional view which expands and shows the other example of the connection layer of Embodiment 1 of the assembled battery which concerns on this invention. It is the elements on larger scale which expand and show the connection layer of Embodiment 2 of the assembled battery which concerns on this invention, Comprising: The longitudinal cross-sectional view which shows the state before welding an external terminal to a connection layer. It is the elements on larger scale which expand and show the connection layer shown in FIG. 8A, Comprising: The longitudinal cross-sectional view which shows the state after welding an external terminal to the connection layer. It is a figure which shows the external appearance of the bus bar of Embodiment 3 of the assembled battery which concerns on this invention, Comprising: The perspective view which shows the state which deposited metal powder on the surface of a bus bar. The longitudinal cross-sectional view of FIG. 9A. It is a figure which shows the external appearance of the bus bar shown to FIG. 9A, Comprising: The perspective view which shows the state which performed the surface processing process on the surface of the metal powder deposited on the surface of a bus bar. FIG. 10B is a longitudinal sectional view of FIG. 10A. The whole perspective view which shows the external appearance of Embodiment 4 of the assembled battery which concerns on this invention. The side view of the assembled battery shown in FIG. The whole perspective view which shows the external appearance of Embodiment 5 of the assembled battery which concerns on this invention.

  Hereinafter, an embodiment of an assembled battery according to the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 shows an appearance of a battery pack according to Embodiment 1 of the present invention. FIG. 2 is a side view of the assembled battery shown in FIG.

  The assembled battery 10 shown in FIG. 1 is manufactured by arranging a plurality of prismatic secondary batteries 100 and connecting adjacent prismatic secondary batteries 100 in series or in parallel via a bus bar 300.

  Each square secondary battery 100 includes a battery can 101 and a battery lid 102. Here, examples of the material for forming the battery can 101 and the battery lid 102 include aluminum and aluminum alloy.

  The battery can 101 has a pair of wide surfaces 101a, a pair of narrow surfaces 101b, and a bottom surface 101c. The battery cans 101 are formed in a rectangular box shape having an open top surface. The wide surfaces 101a are arranged so as to face each other. In addition, a battery element 101 (not shown) is accommodated in the battery can 101, and the upper opening of the battery can 101 is sealed and sealed by a rectangular flat battery cover 102. The battery can 101 and the battery lid 102 are welded by laser welding or the like.

  The battery lid 102 of each prismatic secondary battery 100 is provided with a positive external terminal 141, a negative external terminal 151, and a gas discharge valve 103, and seals a liquid injection hole 106a for injecting an electrolyte into the secondary battery. The liquid stopper 106b to be stopped is welded by laser welding or the like. In addition, a gasket 130 formed of an insulating resin is interposed between the battery lid 102 and the positive external terminal 141 and the negative external terminal 151. Here, as a forming material of the positive electrode external terminal 141, aluminum or an aluminum alloy is generally used, and as a forming material of the negative electrode external terminal 151, copper or a copper alloy is used.

  The bus bar 300 for connecting each square secondary battery 100 has a substantially rectangular flat plate shape, and as a material for forming the bus bar 300, generally the same kind of aluminum or aluminum alloy as that of the positive electrode external terminal 141 is used. Therefore, when the bus bar 300 and the negative electrode external terminal 151 are directly welded, it is difficult to ensure the welding strength between the bus bar 300 and the negative electrode external terminal 151.

  As shown in the figure, the bus bar 300 has a stepped portion 301 at a portion of the lower surface thereof joined to the negative electrode external terminal 151, and the stepped portion 301 is made of a material different from the forming material of the busbar 300. It has a connection layer 300a on which a material excellent in weldability with the material for forming the negative electrode external terminal 151, for example, metal powder made of copper or a copper alloy is deposited. Here, the connection layer 300a and the bus bar 300 are bonded by metal bonding at the interface, and the connection layer 300a and the negative electrode external terminal 151 are connected to each other by a surface processing treatment for reducing the surface roughness. It is welded via the welding surface 300e of the layer 300a.

  That is, as shown in FIG. 2, on the positive electrode external terminal 141 side of the square secondary battery 100, the welding surface (lower surface in the drawing) 300b of the bus bar 300 and the welding surface (upper surface in the drawing) 141b of the positive electrode external terminal 141 Are welded directly, and on the negative electrode external terminal 151 side, the welding surface (lower surface in the drawing) 300e of the connection layer 300a of the stepped portion 301 of the bus bar 300 and the welding surface (upper surface in the drawing) 151b of the negative electrode external terminal 151 are welded. Has been. Thereby, even if the forming materials of the bus bar 300 and the negative electrode external terminal 151 are different, the bus bar 300 and the negative electrode external terminal 151 are joined by joining the bus bar 300 and the negative electrode external terminal 151 through the connection layer 300a. And welding reliability can be ensured.

  Next, with reference to FIGS. 3 to 6, a method for forming a connection layer for the bus bar and a method for joining the bus bar to the rectangular secondary battery will be outlined. FIG. 3 shows the appearance of the bus bar of the assembled battery shown in FIG. 1, and FIGS. 4A to 4C schematically show the process of forming a connection layer on the bus bar of the assembled battery shown in FIG. 4A is an enlarged view, and FIG. 4A illustrates a process of depositing metal powder on the surface of the bus bar, and FIG. 4B illustrates a state in which metal powder is deposited on the surface of the bus bar. FIG. 4C illustrates a state in which surface processing is performed on the surface of the metal powder deposited on the surface of the bus bar. FIG. 5 is a partially enlarged view illustrating a process of welding the bus bar to the rectangular secondary battery, and FIG. 6 is an enlarged view of the welded portion between the bus bar and the external terminal.

  When forming the connection layer 300 a on the surface of the bus bar 300, as shown in FIG. 3, a substantially rectangular plate-like bus bar 300 in which a stepped portion 301 is formed in a portion joined to the negative electrode external terminal 151 is prepared. The shape of the stepped portion 301 in plan view, the depth d of the stepped portion 301 (the distance between the welded surface (upper surface in the drawing) 300b of the bus bar 300 and the bottom surface 301b of the stepped portion 301), etc. It can be appropriately changed according to the shape and welding conditions.

  As shown in FIG. 4A, the connection layer 300a uses a cold spray method to convert a metal powder 400 (for example, a powder made of copper or a copper alloy) at a predetermined temperature into a compressed gas G (for example, nitrogen gas, helium gas, It is formed by pressurizing and accelerating together with air or the like, and spraying and depositing on the bottom surface 301b of the stepped portion 301 of the bus bar 300 in a solid state. At that time, the metal powder 400 contacting the bottom surface 301b of the step portion 301 of the bus bar 300 has a predetermined temperature and a predetermined speed, and is bonded to the bus bar 300 by metal bonding. That is, the metal powder 400 deposited on the bottom surface 301b of the stepped portion 301 of the bus bar 300 and the bus bar 300 are bonded by metal bonding at the interface.

  Here, as shown in FIG. 4B, the connection layer 300 a is formed such that its upper surface 300 c protrudes from the welding surface 300 b of the bus bar 300. Further, the upper surface 300c and the side surface 300d of the connection layer 300a on which the metal powder 400 is deposited using the cold spray method described above have a surface roughness corresponding to the size of the metal powder 400 to be sprayed. . Further, the upper surface 300c and the side surface 300d of the connection layer 300a have the same surface roughness. For example, when the average particle size of the metal powder 400 is several hundred μm, the surface roughness of the upper surface 300 c and the side surface 300 d is about half of the average particle size of the metal powder 400. Further, the surface roughness of the upper surface 300c of the connection layer 300a on which the metal powder 400 is deposited using the cold spray method is larger than the surface roughness of the welding surface 151b (see FIG. 5) of the negative electrode external terminal 151. When the upper surface 300c of the connection layer 300a and the welding surface 151b of the negative electrode external terminal 151 are joined by welding, it is difficult to ensure the welding strength.

  Therefore, as shown in FIG. 4C, the entire upper surface 300c of the connection layer 300a is subjected to a surface treatment for reducing the surface roughness, and the upper surface 300c of the connection layer 300a is subjected to, for example, the welding surface 151b of the negative electrode external terminal 151. A weld surface 300e having a surface roughness equal to or less than that of the weld surface 300b of the bus bar 300 is formed. Here, examples of the surface processing for reducing the surface roughness include cutting processing, polishing processing, and melt processing. The side surface 300d of the connection layer 300a that is not welded to the negative electrode external terminal 151 is not subjected to surface processing for reducing the surface roughness.

  In this way, the bus bar 300 in which the connection layer 300a is formed in the stepped portion 301 is manufactured. As shown in FIG. 5, on the positive external terminal 141 side of the square secondary battery 100, the welded surface 141b of the positive external terminal 141 and the bus bar 300 are provided. The welding surface (upper surface in FIG. 4C) 300b is directly welded. On the other hand, on the negative electrode external terminal 151 side of the prismatic secondary battery 100, the welding surface 151b of the negative electrode external terminal 151 and the welding surface 300e of the connection layer 300a formed on the stepped portion 301 of the bus bar 300 are welded. Here, when welding the welding surface 151b of the negative electrode external terminal 151 and the welding surface 300e of the connection layer 300a formed on the step portion 301 of the bus bar 300, as shown in FIG. The welding conditions are adjusted so that 501 reaches the negative external terminal 151.

  In addition, as a welding method for welding the positive electrode external terminal 141 and the bus bar 300, the connection layer 300a formed on the step portion 301 of the bus bar 300, and the negative electrode external terminal 151, for example, laser welding, resistance welding, arc welding, or the like is applied. Can do. As the welding method, butt welding, fillet welding, or the like can be applied in addition to the overlap welding shown in FIG.

  With such a configuration, in the battery pack 10 in which a plurality of secondary batteries 100 are connected in series or in parallel via the bus bar 300, the bus bar 300 and the positive external terminal 141 are formed of the same material, and the bus bar 300 and the negative external When the forming material of the terminal 151 is different, for example, the positive external terminal 141 is made of aluminum or aluminum alloy, the bus bar 300 is made of the same kind of aluminum or aluminum alloy as the positive external terminal 141, and the negative external terminal 151 is copper or Even in the case of being made from a copper alloy, the bus bar 300 and the negative electrode external terminal 151 are welded via the connection layer 300a that has been subjected to surface processing for reducing the surface roughness. 141 and bus bar 300 while ensuring the welding strength between bus bar 300 and negative electrode external terminal It is possible to secure the welding reliability between 51. Also, a bus bar 300 in which a stepped portion 301 is formed in advance is used, and a connecting layer 300a having a welded surface 300e substantially flush with the welded surface 300b of the busbar 300 is formed on the stepped portion 301, and the welded surface of the connecting layer 300a is formed. 300e and the welding surface 151b of the negative electrode external terminal 151 are welded, for example, when the rectangular secondary battery 100 having substantially the same outer shape is connected via the bus bar 300, the positive electrode external terminal of the adjacent rectangular secondary battery 100 The height of the welding surface 300b of the bus bar 300 with respect to the welding surface 141b of 141 and the height of the welding surface 300e of the connection layer 300a of the stepped portion 301 of the bus bar 300 with respect to the welding surface 151b of the negative electrode external terminal 151 can be made substantially equal. The welding reliability between the positive electrode external terminal 141 or the negative electrode external terminal 151 and the bus bar 300 can be further improved. Kill.

  Note that the bonding strength of the connection layer 300a deposited by spraying the metal powder 400 and the bus bar 300 by metal bonding is greater than the welding strength when the bus bar 300 and the negative electrode external terminal 151 are directly welded.

  In the first embodiment described above, a description has been given of a mode in which the upper surface 300c of the connection layer 300a is subjected to surface processing for reducing the surface roughness to form the weld surface 300e substantially flush with the weld surface 300b of the bus bar 300. The welding surface 300e of the connection layer 300a may be formed lower than the welding surface 300b of the bus bar 300, or the welding surface 300e of the connection layer 300a may be formed higher than the welding surface 300b of the bus bar 300. For example, as shown in FIG. 7, when the welding surface 300e of the connection layer 300a is formed lower than the welding surface 300b of the bus bar 300, the welding surface 300e of the connection layer 300a and the welding surface 300b of the bus bar 300 are formed. The bus bar 300 can be positioned with respect to the negative external terminal 151 using the step.

[Embodiment 2]
FIG. 8A is a partially enlarged view showing the connection layer of Embodiment 2 of the assembled battery according to the present invention in an enlarged manner, showing a state before welding the external terminal to the connection layer, and FIG. The state after welding an external terminal to a connection layer is shown. The second embodiment shown in FIGS. 8A and 8B differs from the first embodiment shown in FIGS. 1 to 6 in the configuration of the connection layer, and the other configurations are the same as those of the first embodiment. Therefore, about the structure similar to Embodiment 1 shown in FIGS. 1-6, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  In the assembled battery 10A shown in FIG. 8A, when the size of the bottom surface 301b of the stepped portion 301 of the bus bar 300 is larger than the size of the welded surface 151b of the negative electrode external terminal 151 in plan view, A part of the surface (lower surface in the figure) 300cA of the connection layer 300aA formed in the stepped portion 301 of the bus bar 300, specifically, a surface approximately at the center of the surface 300cA facing the negative electrode external terminal 151 of the connection layer 300aA. Surface processing for reducing the roughness is performed, and a welding surface 300eA for welding the negative electrode external terminal 151 is formed. Here, the welding surface 300eA of the connection layer 300aA is larger than the size of the welding surface 151b of the negative electrode external terminal 151 in a plan view, for example, less than the surface roughness of the welding surface 151b of the negative electrode external terminal 151, and the bus bar 300 It is formed substantially flush with the welding surface 300b.

  In this way, by performing surface processing for reducing the surface roughness on a part of the surface 300cA of the connection layer 300aA to form the weld surface 300eA, as shown in FIG. 8B, the weld surface 300eA of the connection layer 300aA and When the welding surface 151b of the negative electrode external terminal 151 is joined by welding, contact between the surface 300cA of the connection layer 300aA having a relatively large surface roughness and the negative electrode external terminal 151 is avoided, and the connection layer 300aA The welding reliability between the bus bar 300 and the negative electrode external terminal 151 can be ensured while optimizing the range of the surface treatment applied to the surface 300cA.

[Embodiment 3]
FIG. 9A is a view showing the appearance of the bus bar of Embodiment 3 of the assembled battery according to the present invention, in which a metal powder is deposited on the surface of the bus bar, and FIG. FIG. Moreover, FIG. 10A is a figure which shows the external appearance of the bus bar shown in FIG. 9A, and shows a state in which the surface of the metal powder deposited on the surface of the bus bar is subjected to surface processing, and FIG. It is a longitudinal cross-sectional view of FIG. 10A. The third embodiment shown in FIGS. 9A to 10B is different from the first embodiment shown in FIGS. 1 to 6 in the configuration of the bus bar and the connection layer, and the other configurations are the same as those in the first embodiment. Therefore, the detailed description of the same configuration as that of the first embodiment shown in FIGS. 1 to 6 is omitted.

  As shown in FIGS. 9A and 9B, in the third embodiment, a recess 300fB having a substantially circular and concave cross section is formed in a portion of the welding surface 300bB of the bus bar 300B that is joined to the negative electrode external terminal 151. A metal powder (for example, powder made of copper or copper alloy) at a predetermined temperature accelerated by pressurization with compressed gas (for example, nitrogen gas, helium gas, air, etc.) is sprayed in the solid state in the recess 300fB. Thus, the connection layer 300aB is formed. Here, as shown in FIG. 9B, the connection layer 300aB on which the metal powder is deposited is formed so that the upper surface 300cB protrudes from the welding surface 300bB of the bus bar 300B.

  Then, by subjecting the entire upper surface 300cB of the connection layer 300aB to surface processing for reducing the surface roughness, as shown in FIGS. 10A and 10B, the surface of the connection layer 300aB, for example, a welded surface of the bus bar 300B A weld surface 300eB substantially flush with 300bB is formed. The bus bar 300B having such a welded surface 300eB is used, and on the positive electrode external terminal side, the weld surface of the positive electrode external terminal and the weld surface 300bB of the bus bar 300B are directly welded, and on the negative electrode external terminal side, the negative electrode external terminal The welded surface is welded to the welded surface 300eB of the connection layer 300aB formed in the recess 300fB of the bus bar 300B, and adjacent square secondary batteries are connected via the busbar 300B to produce an assembled battery.

  As described above, the connection layer 300aB is formed in the recess 300fB formed in the portion to be joined to the negative electrode external terminal 151 of the bus bar 300B, so that the size of the connection layer 300aB formed on the welding surface 300bB of the bus bar 300B is optimized. The welding reliability between the bus bar 300B and the negative electrode external terminal 151 can be ensured. In addition, when connecting square secondary batteries having substantially the same external shape in series or in parallel via a bus bar, the positive electrode outside of the adjacent square secondary battery is not adjusted in advance without adjusting the height of the welding surface 300bB of the bus bar 300B. The height of the welding surface 300bB of the bus bar 300B with respect to the welding surface of the terminal and the height of the welding surface 300eB of the connection layer 300aB of the recess 300fB of the bus bar 300B with respect to the welding surface of the negative electrode external terminal can be made substantially equal. In addition, the welding reliability between the negative electrode external terminal and the bus bar 300B can be further improved.

  In the third embodiment described above, the embodiment has been described in which the recess 300fB having a substantially circular and concave cross section is formed on the welding surface 300bB of the bus bar 300B. However, the shape of the recess in plan view is, for example, more than a triangle. It can be changed to an appropriate shape such as a square or a star.

[Embodiment 4]
FIG. 11 shows an appearance of the assembled battery according to the fourth embodiment of the present invention, and FIG. 12 is a side view of the assembled battery shown in FIG. The fourth embodiment shown in FIGS. 11 and 12 is different from the first embodiment shown in FIGS. 1 to 6 in the configuration and materials of the bus bars and connection layers, and the other configurations are the same as those in the first embodiment. . Therefore, about the structure similar to Embodiment 1 shown in FIGS. 1-6, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  In Embodiments 1 to 3 described above, a mode in which the bus bar is made of the same kind of aluminum or aluminum alloy as the positive electrode external terminal has been described in order to reduce the weight of the entire assembled battery. On the other hand, in this Embodiment 4, in order to improve the electroconductivity of the square secondary batteries which comprise an assembled battery, the form by which the bus-bar 800 is produced from the same kind of copper and copper alloy as a negative electrode external terminal is demonstrated.

  As described above, in general, the negative electrode external terminal 151 is made of copper or a copper alloy, and the welding strength between the negative electrode external terminal 151 and the bus bar 800 is easy even if the negative electrode external terminal 151 and the bus bar 800 are directly welded. Can be secured. On the other hand, the positive external terminal 141 is made of aluminum or an aluminum alloy. When the positive external terminal 141 and the bus bar 800 are directly welded, it is difficult to ensure the welding strength between the positive external terminal 141 and the bus bar 800.

  In the fourth embodiment, as shown in FIG. 11, a substantially rectangular flat-shaped bus bar 800 in which a stepped portion 801 is formed at a portion to be joined to the positive electrode external terminal 141 is prepared, a cold spray method is used, and a predetermined temperature is set. A metal powder (for example, a powder made of aluminum or an aluminum alloy) is pressurized with a compressed gas (for example, nitrogen gas, helium gas, air, etc.) and accelerated, and solid phase is applied to the bottom surface 801b of the stepped portion 801 of the bus bar 800. The connection layer 800a is formed on the stepped portion 801 by spraying and depositing in the state. Note that the metal powder constituting the connection layer 800a and the bus bar 800 are joined by metal bonding at the interface. Then, the surface of the connection layer 800a on which the metal powder is deposited is subjected to surface processing for reducing the surface roughness to form a weld surface 800e substantially flush with the weld surface 800b of the bus bar 800, and the connection layer 800a is welded. The surface 800e and the welding surface of the positive external terminal 141 are welded.

  That is, as shown in FIG. 12, the welding surface 800b of the bus bar 800 and the welding surface 151b of the negative electrode external terminal 151 are directly welded on the negative electrode external terminal 151 side of the square secondary battery 100, and on the positive electrode external terminal 141 side, The welding surface 800e of the connection layer 800a of the stepped portion 801 of the bus bar 800 and the welding surface 141b of the positive electrode external terminal 141 are welded.

  Thereby, even when the bus bar 800 is made of a different kind of copper or copper alloy from the positive electrode external terminal 141, the bus bar 800 is connected to the bus bar 800 via the connection layer 800a formed of, for example, metal powder made of aluminum or aluminum alloy. Since the positive external terminal 141 is joined, welding reliability between the bus bar 800 and the positive external terminal 141 can be ensured.

[Embodiment 5]
FIG. 13 shows the external appearance of Embodiment 5 of the assembled battery according to the present invention.

  The illustrated assembled battery 10 </ b> D is produced by arranging a plurality of cylindrical secondary batteries 600 and connecting adjacent cylindrical secondary batteries 600 in series or in parallel via a bus bar 700.

  Each cylindrical secondary battery 600 includes a battery can 601, a battery lid 602, and a gasket 603. Here, examples of the material for forming the battery can 601 include iron and an iron alloy, and examples of the material for forming the battery lid 602 include aluminum and an aluminum alloy.

  An electric storage element (not shown) is accommodated inside the bottomed and cylindrical battery can 601, and the upper opening of the battery can 601 is sealed and sealed with a disk-shaped battery lid 602 via a gasket 603. ing. Here, the battery cover 602 also serves as a positive external terminal, and the battery can 601 also serves as a negative external terminal.

  The bus bar 700 for connecting each secondary battery 600 has a substantially rectangular flat plate shape, and examples of the forming material include copper and a copper alloy. Therefore, when the battery lid 602 and the bus bar 700 constituting the positive external terminal and the battery can 601 and the bus bar 700 constituting the negative external terminal are directly welded, it is difficult to ensure the welding strength between the external terminal and the bus bar 700.

  As shown in the figure, the bus bar 700 is joined to both ends in the longitudinal direction, specifically, a portion of the surface joined to the battery lid 602 constituting the positive external terminal and the battery can 601 constituting the negative external terminal. The step portions 701a and 701b are respectively provided in the portions to be formed, and each step portion 701a and 701b is made of a material different from the forming material of the bus bar 700 and has excellent weldability with the battery lid 602 or the battery can 601. It has connection layers 700aa and 700ab on which metal powder made of a material is deposited. Specifically, the bus bar 700 has a connection layer 700aa on which a metal powder made of aluminum or an aluminum alloy is deposited on the step portion 701a on the positive electrode external terminal side, and nickel on the step portion 701b on the negative electrode external terminal side. And a connection layer 700ab on which metal powder made of nickel alloy is deposited. Here, each of the connection layers 700aa and 700ab and the bus bar 700 are joined by metal bonding at the interface, and the connection layer 700aa and the battery lid 602 and the connection layer 700ab and the battery can 601 reduce the surface roughness. Are welded via the welding surfaces 700ea and 700eb of the connection layers 700aa and 700ab that have been subjected to surface processing.

  That is, in the assembled battery 10D of the fifth embodiment, on the positive electrode side of the cylindrical secondary battery 600, a battery lid 602 made of aluminum or aluminum alloy and a connection made of metal powder made of aluminum or aluminum alloy are connected. A metal powder made of a battery can 601 made of iron or an iron alloy on the negative electrode side and nickel or nickel alloy (a material excellent in weldability with iron or iron alloy, copper or copper alloy) on the negative electrode side The connection layer 700ab composed of the body is welded. Thereby, even if the forming material of the bus bar 700 and the forming material of the battery lid 602 constituting the positive electrode external terminal and the forming material of the bus bar 700 and the forming material of the battery can 601 constituting the negative electrode external terminal are different from each other. The bus bar 700 and the battery lid 602 and the battery can 601 are joined to each other through the connection layers 700aa and 700ab subjected to surface processing for reducing the surface roughness, whereby the bus bar 700 and the battery lid 602 Welding reliability with the battery can 601 can be ensured.

[Embodiments 6 to 12]
In Embodiment 5 described above, for example, the battery lid 602 constituting the cylindrical secondary battery 600 is made of aluminum (Al) or an aluminum (Al) alloy, and the battery can 601 is made of iron (Fe) or iron (Fe) alloy. When the bus bar 700 that connects each secondary battery 600 is made of copper (Cu) or a copper (Cu) alloy, the positive-side connection layer 700aa formed at the step portion of the bus bar 700 is aluminum ( The embodiment has been described in which the negative electrode-side connection layer 700ab is formed of a metal powder made of nickel (Ni) or a nickel (Ni) alloy. The material for forming the metal powder forming the layers 700aa and 700ab and the necessity of the connection layers 700aa and 700ab are as follows: battery lid 602, battery can 601 and bus bar It can be changed according to the 00 formation material. Table 1 below shows the formation of metal powder that forms the battery lid 602, the battery can 601, the bus bar 700, and the connection layers 700aa and 700ab, which can ensure the welding reliability between the bus bar 700 and the battery lid 602 and the battery can 601. The combination of materials (Embodiments 6 to 12) is shown. Table 1 also shows metal powder forming materials for forming the battery lid 602, the battery can 601, the bus bar 700, and the connection layers 700aa and 700ab of Embodiment 5 described above.

  As shown in Table 1, the battery bar 602, the battery can 601, the bus bar 700, and the metal powder forming material for forming the connection layers 700aa and 700ab are appropriately combined to form the bus bar 700, the battery cover 602, and / or the bus bar 700. Even when the forming material of the battery can 601 is different, the welding reliability of the bus bar 700 and the battery lid 602 or the bus bar 700 and the battery can 601 can be ensured. In particular, in Embodiments 6, 8, 9, and 12, one of the connection layers 700aa and 700ab formed at the stepped portion of the bus bar 700 can be omitted, and the productivity of the assembled battery can be increased.

  In the first to fifth embodiments described above, the connection layer is described as being formed from metal powder made of aluminum, an aluminum alloy, copper, a copper alloy, nickel, or a nickel alloy. You may form from the metal powder which consists of iron alloys.

  Moreover, in Embodiment 1-5 mentioned above, in order to ensure the welding strength of the welding surface of a connection layer, and the welding surface of an external terminal, the welding surface of a connection layer is below the surface roughness of the welding surface of an external terminal. Although the form has been described, since the connection layer is formed of a material excellent in weldability with the external terminal, the welding surface of the connection layer only needs to be subjected to a surface processing treatment that reduces at least the surface roughness.

  In addition, this invention is not limited to above-described Embodiment 1-12, Various deformation | transformation forms are included. For example, the above-described first to twelfth embodiments are described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

10 assembled battery 100 square secondary battery 101 battery can 101a wide surface 101b narrow surface 101c bottom surface 102 battery lid 103 gas discharge valve 106a liquid injection hole 106b liquid injection plug 130 gasket 141 positive electrode external terminal 141b positive electrode external terminal welding surface 151 negative electrode External terminal 151b Weld surface 300 of negative electrode external terminal Bus bar 300a Connection layer 300b Weld surface 300d of bus bar Side surface 300e of connection layer 301 Weld surface 301 of connection layer Stepped portion 301b Bottom surface of stepped portion 400 Metal powder 500 Melting portion 501 Tip portion 600 Cylinder Secondary battery 601 Battery can 602 Battery lid 603 Gasket 700 Bus bar 700aa Connection layer 700ab Connection layer 701a Stepped portion 701b Stepped portion 800 Busbar 800a Connection layer 801 Stepped portion G Compressed gas

Claims (8)

A plurality of secondary batteries having positive and negative external terminals are connected through a bus bar,
Between the external terminals of the secondary battery and at least one external terminal and the bus bar, a material different from the bus bar forming material and having excellent weldability with the external terminal forming material A connection layer formed by depositing metal powder is interposed,
Wherein the connection layer and the bus bar are bonded by metallic bond at the interface, and the connecting layer wherein the external terminal is welded through the welding surface before Symbol connecting layer and the welding surface of the external terminal the assembled battery weld surface roughness of the connecting layer, wherein a surface roughness less der Rukoto the weld surface of the external terminal. A plurality of secondary batteries having positive and negative external terminals are connected through a bus bar,
Between the external terminals of the secondary battery and at least one external terminal and the bus bar, a material different from the bus bar forming material and having excellent weldability with the external terminal forming material A connection layer formed by depositing metal powder is interposed,
The connection layer and the bus bar are joined by metal bonding at the interface, and the connection layer and the external terminal are welded via a welding surface of the connection layer, and the welding surface of the connection layer is flat. A battery pack characterized by having a smooth surface. The metal powder is excellent in weldability with the same material as the external terminal forming material, or with the external terminal forming material, and is made of a material different from the external terminal forming material. Item 3. The assembled battery according to Item 1 or 2 . The connecting layer is assembled battery according to claim 1 or 2, characterized in that it is formed on the surface of the formed step portion or recess of the bus bar. The weld surface of the connection layer is assembled battery according to claim 1 or 2, characterized in that it is formed in a part of the surface facing the external terminal of the connection layer. The assembled battery according to claim 1 or 2 , wherein the secondary battery constituting the assembled battery is rectangular or cylindrical. The assembled battery according to claim 1 or 2 , wherein the metal powder is made of aluminum, copper, nickel, iron, or an alloy thereof. An assembled battery manufacturing method for manufacturing the assembled battery according to claim 1, comprising:
Includes a step of performing surface treatment to reduce the surface roughness of the weld surface of the connection layer, wherein the surface treatment is a battery assembly, wherein the cutting process, grinding process, or a melt processing Manufacturing method .

Images