JP5100140B2 - Battery pack and manufacturing method thereof - Google Patents

Description

  The present invention relates to a battery pack in which a plurality of battery cells are connected in series and / or in parallel, and a method for manufacturing the same.

Battery packs (pack batteries) or battery packs used as power sources for electric vehicles and hybrid vehicles are required to have high output in a limited space. Square batteries with better energy density than cylindrical batteries are required. Sometimes used. In particular, a lithium ion battery is required to be adopted because it has a high energy density per unit volume and can easily achieve high output. However, in a battery pack in which a plurality of lithium ion batteries are connected in series or in parallel as battery cells, it is necessary to detect the voltage (intermediate voltage) of electrode terminals that connect the battery cells for battery control. For this reason, a terminal for detecting an intermediate voltage is connected to each electrode terminal. A battery pack composed of battery cells to which such voltage detection terminals are connected and the battery cells are shown in FIGS. In these drawings, FIG. 22 is a perspective view of the battery pack 300, FIG. 23 is a perspective view of the battery cell stack constituting the battery pack 300, FIG. 24 is an enlarged perspective view of the electrode terminal portion of FIG. FIG. 26 is a side view, FIG. 27 is a front view, and FIG. 28 is a schematic cross-sectional view showing a state where power is supplied to the electrode terminals. As shown in these figures, when the electrode terminals 12 of the battery cell 10 are screwed together with a bolt 52, the voltage detection terminal 70 is also tightened together to electrically connect the voltage detection terminal 70 to the electrode terminal. is doing.
JP-A-5-343105

  However, in this structure, when using a battery cell in which the metal constituting the electrode terminal is different between the positive electrode and the negative electrode, such as a lithium ion battery, there is a problem that the electrode terminal is easily corroded. Specifically, from the viewpoint of workability of fastening work, etc., as shown in the enlarged view of FIG. 24 and the like, when fastening by screwing, the voltage detection terminal 70 is overlaid on the upper surface of the electrode terminal, The bolt is inserted and fixed. Here, the lithium ion battery generally includes a positive electrode made of Al and a negative electrode made of Cu. For this reason, when water droplets or the like adhere to the electrode terminals due to the difference in ionization tendency between Al and Cu, electrolytic corrosion occurs between the electrode terminals. Also, as shown in the cross-sectional view of FIG. 28, during energization, a large current is energized between the electrode terminals stacked so as to be in direct contact, and conversely, no large current flows through the voltage detection terminal 70 stacked above. For this reason, a small current or a minute current is likely to flow in a vortex, and when a water droplet adheres, it becomes easy for electrons to move to that position, which is also a factor that tends to cause galvanic corrosion. When the corrosion of the electrode terminal proceeds due to the electric corrosion, the contact resistance increases or a contact failure is caused, leading to a decrease in reliability.

  The present invention has been made to solve such conventional problems. A main object of the present invention is to provide a battery pack that suppresses the occurrence of electrolytic corrosion at an electrode terminal and has improved reliability, and a manufacturing method thereof.

Means for Solving the Problems and Effects of the Invention

In order to achieve the above object, a battery pack of the present invention is a battery pack in which a plurality of battery cells are adjacent to each other and connected in series with each other, with positive and negative electrode terminals protruding from one end face, and a positive electrode And a plurality of battery cells using metals with different ionization tendency at the negative electrode, a voltage detection terminal having a connection surface for electrically connecting to the electrode terminal of the battery cell in order to measure the terminal voltage of the battery cell, The battery cell is provided with a fixture for fixing and connecting the positive electrode and the negative electrode of the adjacent battery cells in a state in which the end surfaces provided with the electrode terminals are arranged in a substantially same plane. The plate-like electrode terminal protrudes upward from the end surface of the battery cell, has a bent surface with the tip bent, and is between the bent surfaces of the positive and negative electrode terminals of adjacent battery cells. Through the connection surface of the voltage detection terminal. By superimposing them in a state of being, linked in a fixed state with the fixture. The connection surface of the voltage detection terminal is made of a metal having an ionization tendency intermediate between the ionization tendency of the metal constituting the positive electrode terminal and the ionization tendency of the metal constituting the negative electrode terminal. Thereby, by causing a charge / discharge current to flow between the electrode terminals, it is possible to suppress the occurrence of electrolytic corrosion even when water droplets or the like adhere, and to improve the reliability of the electrode terminals.

  Another battery pack is a battery pack in which a plurality of battery cells are adjacent to each other and connected in series with each other, with positive and negative electrode terminals protruding from one end face, and metals having different ionization tendency between the positive electrode and the negative electrode. A plurality of battery cells to be used, a voltage detection terminal having a connection surface for electrically connecting to the electrode terminal of the battery cell in order to measure the terminal voltage of the battery cell, and the battery cell provided with the electrode terminal A fixing device for fixing and connecting the positive and negative electrodes of adjacent battery cells in a state where the end surfaces are arranged substantially on the same plane, and the connection surface of the voltage detection terminal is connected to the positive electrode terminal. The difference in ionization tendency between the metal constituting the metal and the metal constituting the electrode terminal of the negative electrode is less than the difference in ionization tendency between the metal constituting the positive electrode and the negative electrode, and the electrode terminal is plate-shaped. Formed, plate-shaped The electrode terminal protrudes upward from the end face of the battery cell, has a bent curved surface by bending the tip, and the voltage detection terminal between the positive and negative electrode terminals of the adjacent battery cell. These are overlapped with a connection surface interposed, and are connected to a fixed state by a fixing tool. This makes it possible to suppress the occurrence of electrolytic corrosion even when water droplets adhere, by interposing the connection surface of the voltage detection terminal made of a metal with a small difference in ionization tendency between the electrode terminals, thereby improving the reliability of the electrode terminals. It can be improved.

  The battery cell is preferably a lithium ion battery, and the connection surface of the voltage detection terminal is Ni or Ni-Cr plated Cu or Ni. Thereby, the reliability of the battery pack using the lithium ion battery in which the positive electrode is made of a metal plate such as Al and the negative electrode is made of Cu can be improved with a simple configuration.

  In addition, a connecting hole is formed on the bent surface of the electrode terminal, and a detecting terminal hole is formed on the connecting surface of the voltage detection terminal with an inner diameter substantially equal to or larger than the connecting hole. The insertion body is inserted through the connection hole, and the insertion body is substantially perpendicular to the end face of the battery cell in a state where the bent surface of the positive and negative electrode terminals and the detection terminal hole of the connection surface interposed therebetween are aligned. It can also be configured to penetrate in any direction. Thereby, when connecting electrode terminals with a fixing tool, the terminal for voltage detection can be fastened together. Further, the connection work can be performed from the upper surface of the battery pack, and an advantage of excellent workability can be obtained.

  Further, the battery cell is a square battery, the electrode terminal is bent so as to protrude obliquely from the end face of the battery cell, and the bent curved face is bent in a posture substantially perpendicular to the end face of the battery cell. It can also be located in substantially the same plane as the side surface of the battery cell. As a result, the electrode terminals themselves of adjacent battery cells can be bent so that the bent surfaces can come into contact with each other, and the connection can be facilitated.

  Furthermore, a pair of electrode terminals may be projected apart from the end face of the battery cell, and each electrode terminal may be configured to project obliquely in different directions. Thereby, the serial connection of adjacent battery cells can be performed easily.

  Alternatively, the battery cell is a square battery, and the electrode terminal protrudes from the end surface of the battery cell in a substantially vertical direction, and the tip is bent into a substantially L-shaped cross section so as to be parallel to the end surface, thereby forming a horizontal folding surface. Alternatively, the battery cells may be configured so that adjacent battery cells overlap with each other and are connected with a fixture. Thereby, between adjacent battery cells, a horizontal folding surface can be piled up and connected with a fixture, and another member such as a bus bar can be dispensed with.

  The pair of electrode terminals can be bent such that one bending direction is opposite to the other bending direction. Thereby, the battery cell which adjoins on both surfaces of a battery cell and each electrode terminal can be connected, and series connection can be implement | achieved easily.

  Preferably, the bending position of one of the pair of electrode terminals is shorter than the bending position of the other electrode terminal by an amount corresponding to the sum of the thickness of the electrode terminal and the voltage detection terminal. Bend it. Accordingly, when adjacent battery cells are connected to each other, it becomes easy to superimpose folded curved surfaces offset by the thicknesses of the electrode terminals and the voltage detection terminals, and the battery cells can be arranged accurately.

  The fixture includes a bolt and a nut, and the bolt is inserted from one side into a connecting hole of a curved surface obtained by overlapping the curved surfaces of electrode terminals of adjacent battery cells, and the other is fixed by screwing the other into the nut. Can do. Thereby, a battery cell can be reliably electrically connected by screwing of a volt | bolt and a nut.

  Alternatively, the fixture includes a bolt and a burring portion in which a screw groove is formed by burring a connection hole of one folding surface, and the folding surface of the electrode terminals of adjacent battery cells is a folding surface having a burring portion. It is also possible to superimpose so as to be positioned below, and to insert a bolt from above the connecting hole and screw it into the screw groove of the burring portion to fix it. Accordingly, the battery cells can be reliably electrically connected by screwing without separately preparing a nut.

  Alternatively, the fixture includes a bolt and a nut portion that fixes a nut so that the opening is aligned with the connection hole of one folding surface, and the folding surface of the electrode terminals of adjacent battery cells has a nut portion. Can be positioned so as to be positioned below, and a bolt can be inserted from above the connecting hole and screwed into the nut portion to be fixed. Accordingly, the battery cells can be reliably electrically connected by screwing without separately preparing a nut.

  On the other hand, an elastic member may be provided on the connection surface of the voltage detection terminal, and the elastic member may be connected to be interposed between the electrode terminals. Thereby, the connection surface can be provided with a function as an elastic member, and can be prevented from being loosened by being interposed between the electrode terminals, and the workability can be further improved.

  On the other hand, an elastic member can be interposed between the fixture and the contact surface with the electrode terminal. Thereby, a connecting surface is pressed with an elastic member, a frictional force is raised, and the loosening prevention effect is acquired. A spring washer can be used for this elastic member. As a result, the fixing device can be prevented from loosening at low cost.

  Alternatively, two or more connecting holes are opened in each folded curved surface, and a fixing tool is passed through each connecting hole and fixed, and the detecting terminal hole on the connection surface is matched with at least one connecting hole and the fixing tool is passed through. Can also be fixed. As a result, the fixture can be doubled or tripled or more to further increase the fastening force of the electrode terminals and improve the reliability.

  Also, an elastic member may be placed in one connecting hole and sandwiched between the fixture and the folded curved surface, and a voltage detection terminal may be placed in the other coupling hole and sandwiched between the fixture and the folded curved surface. it can. Thereby, in addition to increasing the fastening force by making the fixture double or triple, it is possible to efficiently connect the elastic member on one side and the voltage detection terminal on the other side.

  On the other hand, the battery pack manufacturing method is a battery pack manufacturing method in which a plurality of battery cells are adjacent to each other and connected in series with each other, and a plurality of metals having different ionization tendency at the positive electrode terminal and the negative electrode terminal are used. A step of opening a connection hole at the tip of a pair of electrode terminals projecting upward from the end surface of the battery cell and bending the tip to form a curved surface, and for measuring the terminal voltage of the battery cell The connection surface of the voltage detection terminal for electrical connection with the electrode terminal of the battery cell is more positive than the difference in ionization tendency between the metal constituting the positive electrode terminal and the metal constituting the negative electrode terminal. The battery cells are adjacent to each other in a state in which the difference in ionization tendency from the metal constituting the negative electrode and the metal constituting the negative electrode is small, and the battery cells are arranged in a state where the end surfaces provided with the electrode terminals are aligned on the substantially same plane. Positive electrode and During the bent surface of the pole of the electrode terminal can be superimposed them while interposing the connecting surface of the voltage measuring terminals, and a step of connecting to a fixed state with the fixture. This makes it possible to suppress the occurrence of electrolytic corrosion even when water droplets adhere, by interposing the connection surface of the voltage detection terminal made of a metal with a small difference in ionization tendency between the electrode terminals, thereby improving the reliability of the electrode terminals. It can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a battery pack and its manufacturing method for embodying the technical idea of the present invention, and the present invention specifies the battery pack and its manufacturing method as follows. do not do. Moreover, the member shown by the claim is not what specifies the member of embodiment. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference numeral indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.
(Embodiment 1)

FIG. 1 is an external perspective view of battery pack 100 according to Embodiment 1 of the present invention, FIG. 2 is a perspective view of battery cell laminate 1 constituting battery pack 100, and FIG. 3 is an electrode terminal of FIG. 4 is an enlarged perspective view of FIG. 12, FIG. 4 is an exploded perspective view of FIG. 3, FIG. 5 is a plan view of the battery cell laminate 1 of FIG. 2, FIG. 6 is a side view, FIG. FIG. 8 is a schematic cross-sectional view showing how the electrode terminal 12 is energized. A battery pack 100 shown in FIG. 1 is a battery pack for in-vehicle use, and is configured by alternately stacking a plurality of battery cells 10 and separators 20 and covering the left and right end surfaces with end plates 30. Specifically, the rectangular battery cells 10 are sandwiched between frame-shaped separators 20 and stacked in multiple stages with the upper and side surfaces of the battery cells 10 exposed. In this example, nine battery cells 10 are stacked on the main surface. In addition, the separator is abbreviate | omitted in the example of FIGS.
(Battery cell 10)

  As the battery cell 10, a substantially rectangular prismatic battery covered with a prismatic outer can is used. Square battery cells can be arranged more efficiently than cylindrical batteries, and can increase the energy density per unit volume. Especially for in-vehicle applications, there is a high demand for space saving, which is preferable. For such a battery cell, a rectangular secondary battery such as a lithium ion secondary battery can be used. Moreover, it is good also as a primary battery other than a nickel battery. The electrode terminals 12 of the battery cells 10 are connected in series or in parallel. Furthermore, it is connected to a control circuit (not shown) at the end of the battery pack 100, and the voltage, current, temperature, etc. of each battery cell 10 is measured by the control circuit, and the battery capacity and required charge / discharge amount are determined. Control such as charging and discharging is performed.

As shown in the perspective view of FIG. 2, the battery cell 10 has positive and negative electrode terminals 12 protruding from the upper surface of a rectangular outer can whose sides are chamfered. The position where the electrode terminal 12 protrudes is set to a position where the positive electrode and the negative electrode are symmetrical on the main surface of the outer can. Thereby, when the battery cell 10 is turned over and overlapped, the positive electrode and the negative electrode can be overlapped, and series connection can be easily performed. Each of the electrode terminals 12 is bent into an L-shaped cross section, and a connecting hole 13 is opened in a folding surface 12a, which is a further bent piece, to a size that allows the insertion member of the fixture FS to be inserted. In particular, as shown in FIG. 2, the positive and negative electrode terminals 12 are bent in opposite directions, and are formed in a size and shape that allow the electrode terminals 12 to be directly connected to adjacent battery cells 10. Thereby, it becomes easy to connect the positive electrode and the negative electrode directly between adjacent battery cells 10 and connect the battery cells 10 in series or in parallel. As shown in FIG. 2, the battery cell 10 is formed with terminal ribs 14 standing upright so as to surround the periphery of the electrode terminal 12, whereby the electrolyte in the outer can is leaked from the periphery of the electrode terminal 12. Even so, the situation of inadvertent spreading is prevented.
(Separator 20)

As shown in FIG. 1, the battery cell 10 is coated on the outside so as to be sandwiched by separators 20 from both sides. The separator 20 is configured in a frame shape having a size covering the battery cell 10, and exposes both side surfaces and upper and lower end surfaces of the battery cell 10 in a state of covering the battery cell 10, and covers the four corners. Further, the adjacent separators 20 are stacked with the corners in contact with each other. The separator 20 is composed of a member having excellent heat resistance and heat insulation, and is preferably formed of a lightweight and inexpensive resin. For example, a synthetic resin such as polypropylene or polyurethane having a low thermal conductivity (preferably 0.5 W / m or less) can be used. Thereby, while protecting the battery cell 10 with the separator 20, the adjacent battery cells 10 are insulated and insulated. In addition, a slit having a concavo-convex cross section is formed on the bottom surface of the separator 20, and the battery cell 10 is cooled from the side by passing a cooling medium through the slit. In addition, it can also be set as the structure which does not use a separator.
(End plate 30)

In the state where the separators 20 and the battery cells 10 are alternately connected to each other as described above, the end surfaces are covered with the end plate 30 and fixed. The end plate 30 is formed in a size that can cover the battery cell 10 exposed at the end face, and is fixed to be sandwiched from both sides. In this example, a pair of screw holes 32 are protruded from the side surface of the end plate 30, and the end plates 30 are fixed by screwing through extension bolts 34 extended to the side surface of the battery pack 100 on which the battery cells 10 are stacked. The end plate 30 is preferably made of metal or resin, which can be molded by integral molding.
(Electrode terminal 12)

As shown in FIGS. 5 and 7, the electrode terminal 12 bends the positive electrode and the negative electrode in an L-shaped cross section in opposite directions. At this time, the bending positions of the electrode terminals 12 are not the same, and either the positive electrode or the negative electrode is offset by an amount corresponding to the sum of the thickness of the electrode terminal 12 and the thickness of the voltage detection terminal 70. Yes. Accordingly, when the battery cells 10 are stacked as shown in FIG. 7, the folding surfaces 12a of the adjacent battery cells 10 can be overlapped while the end surfaces of the battery cells 10 are maintained substantially on the same plane.
(Voltage detection terminal 70)

  Further, the voltage detection terminal 70 is connected to the battery cell 10 in order to detect an intermediate voltage when the plurality of battery cells 10 are connected in series. In a battery pack using a plurality of lithium ion batteries, it is necessary to detect the terminal voltage of each battery cell. For this reason, a voltage detection terminal is electrically connected to each folding surface. As shown in FIG. 4, the voltage detection terminal 70 is connected to a control circuit (not shown) that detects battery voltage and controls charging and discharging. The voltage detection terminal 70 includes a connection surface 72 for making electrical contact with the electrode terminal 12 in surface contact. The connection between the voltage detection terminal 70 and the electrode terminal 12 can be made common to the connection between the folding surfaces 12a, so that the connection work can be saved by using the same fixture FS. For this reason, the detection terminal hole 71 is formed in the connection surface 72 with an inner diameter substantially equal to or larger than the connection hole 13. Thereby, in the state which made the folding surface 12a of the positive / negative electrode terminal 12 and the connection hole 13 of the connection surface 72 correspond, the penetration body of the fixing tool FS can be inserted through these, and it can fasten together. Further, by opening the connecting hole 13 and the detection terminal hole 71 on the upper surface side of the battery pack 100, that is, on the horizontal plane, the insertion member of the fixture FS can be penetrated in a substantially vertical direction from the upper surface side of the battery pack 100, Since each electrode terminal 12 can be fixed at a stretch from the upper surface side of the battery pack 100, the workability is excellent.

  When the electrode terminal 12 and the voltage detection terminal 70 are fixed by the fixture FS, the connecting surfaces 72 of the voltage detection terminals 70 are not stacked on the upper side as shown in FIG. It arranges so that it may insert between. Thereby, generation | occurrence | production of the electric corrosion in the electrode terminal 12 can be suppressed. Here, metals having different ionization tendencies are used for the electrode terminal 12 of the battery cell 10 between the positive electrode and the negative electrode. When such dissimilar metal electrode terminals 12 are directly stacked, electrolytic corrosion occurs at the contact interface. That is, when water droplets or the like adhere to the electrode terminal 12, ions can move through moisture, and thus a battery is formed at this portion and a chemical reaction (corrosion) occurs. In particular, when the electrode terminals 12 are directly overlapped as shown in FIG. 28, the charge / discharge current flows in a concentrated manner between the bent surfaces 12a of the electrode terminals 12 (thick line arrows in FIG. 28). A large current does not flow through the stacked voltage detection terminals 70. For this reason, it will be in the state where a small electric current flows easily in a vortex. When a water droplet adheres as described above in this state, an ionic current flows in a loop shape (thin arrow in FIG. 28), and the corrosion reaction proceeds.

  In order to avoid such a problem, in this embodiment, a voltage detection terminal 70 is interposed between the electrode terminals 12 as shown in FIG. As a result, as shown in FIG. 8, since a large current flows also to the voltage detection terminal 70 sandwiched between the electrode terminals 12, a small current (a broken line arrow in FIG. 8) hardly flows. This is because electrons tend to move in the direction in which a large current flows, and conversely, in order to form a new current path, a certain amount of energy is required, so that the ionic current tends to flow along the current path. Because there is. Therefore, it becomes difficult to form a local ion current loop, and it is difficult to generate a reaction that causes electrolytic corrosion. Therefore, the occurrence of corrosion is suppressed, and the contact failure of the electrode terminal 12 can be reduced to improve the reliability.

  In this example, a lithium ion battery is used as the battery cell 10, and the positive electrode terminal 12 is made of Al and the negative electrode is made of a Cu metal. As the voltage detection terminal 70, a copper round terminal plated with nickel was used. However, nickel round terminals can also be used. Since the ionization tendency of nickel is intermediate between copper and aluminum constituting the electrode terminal, it can be expected to suppress the occurrence of electrolytic corrosion also in this respect. Furthermore, other materials having a higher ionization tendency than aluminum, such as magnesium, can be used as the voltage detection terminal. In addition, the entire voltage detection terminal is made of such a metal or other material, and only the connection surface 72 with the electrode terminal is made of these materials, or the surface is coated with these materials. it can. From the viewpoints of cost, availability, ease of processing and storage, durability, and the like, nickel is the most preferable material for the connection surface of the voltage detection terminal.

  In addition, in the example of FIG. 3, the electrode terminal stacked on the upper side is the positive electrode and the electrode terminal stacked on the lower side is the negative electrode. Conversely, even if the negative electrode is positioned on the upper side and the positive electrode is positioned on the lower side, It goes without saying that similar results can be obtained.

  Further, by interposing the voltage detection terminal between the electrode terminals, an effect that the voltage detection terminal can be protected at the time of fastening is also obtained. Generally, a round terminal or a Y terminal having a thin shape is often used as a voltage detection terminal as compared with an electrode terminal. For this reason, when the voltage detection terminal is overlapped on the electrode terminal and is fixed with a fixing tool such as a bolt, the electrode terminal is deformed by a rotational torque for tightening the bolt, and there is a possibility that the fastening failure or the terminal disconnection may occur. On the other hand, the voltage detection terminal is sandwiched and fixed between the electrode terminals, and it is not directly affected by the rotational torque from the bolt, so that the occurrence of defects such as deformation can be avoided. If the voltage detection terminal is not an existing round terminal but is a custom-made product with an increased thickness of the connection surface in order to increase the strength, the cost increases. In particular, in the case of a lithium ion battery, since the intermediate voltage is detected by all electrodes, the number of terminals increases and the cost cannot be ignored. Also in this respect, the above-described configuration that can use an existing inexpensive voltage detection terminal is advantageous.

  Furthermore, if the voltage detection terminal of the round terminal is placed on the electrode terminal and a rotary fixing tool such as a bolt is fastened, there is a possibility that it will be rotated by the rotation of the bolt, and a rotation stopping mechanism or the like is required. However, by interposing between the electrode terminals, such a problem does not occur, and the fastening operation is facilitated.

  The electrode terminals 12 superposed in this way are fixed using a fixing tool FS. When the folding surfaces 12a of the adjacent battery cells 10 are overlapped, the connecting holes 13 opened in the respective folding surfaces 12a are at least partially matched, and an insertion body for the fixture FS is inserted therein. At this time, by increasing the inner diameter of the connecting hole 13 of the upper folded curved surface 12a among the folded curved surfaces 12a to be superimposed, the dimensional tolerance can be absorbed and alignment can be facilitated.

The connecting hole 13 is not limited to a circular shape, and may be a long hole. As a result, fine adjustment of the alignment is further facilitated, and the load on the terminal portion can be reduced as compared with the case where the position is completely fixed by welding. Or a connection hole is not restricted to a through-hole, It is good also as a notch shape. Thereby, formation of notch shape and attachment work can be facilitated.
(Fixture FS)

  In the example of FIGS. 1-8, the volt | bolt 52 is used as the fixing tool FS. For example, the bolt 52 is inserted into the connecting hole 13 as an insertion body from the upper surface side of the folding surface 12a, and the nut 53 is disposed on the lower side and screwed together. The nut 53 uses a square nut such as a square nut or a hexagon nut to facilitate screwing. It is also possible to release the fixed state of the battery cell 10 once connected by screwing and disassemble it again. On the other hand, a mechanism for holding the nut 53 on the lower side of the folding surface 12a is required at the time of screwing, and workability is deteriorated.

  Therefore, this problem can be solved by using a fixture that does not use a nut. For example, in the example of FIG. 9, burring is performed on the connecting hole 13 of the bent surface 12a on the lower side of the electrode terminal 12D of the battery cell 10C according to the modification to provide a burring portion 13D having a thread groove. Thereby, the battery cell 10C can be reliably electrically connected by screwing without preparing a separate nut. Since burring is relatively easy, a fixture can be realized easily and inexpensively.

  It is more preferable that the burring portion 13D is provided on the aluminum electrode terminal 12D. This is because it is softer and easier to process than copper. For this reason, when fastening by burring, it can be said that it is preferable that the electrode terminal overlapped on the upper side is a copper negative electrode, and the electrode terminal stacked on the lower side is an aluminum positive electrode.

As another modification, as shown in FIG. 10, a nut portion 13E may be provided in which a nut is fixed so that the opening is aligned with the connection hole 13 of the bent surface 12a of the electrode terminal 12E on the lower side of the battery cell 10D. . This configuration has the advantage of being stronger in strength than the method using the burring portion. For fixing the nut, a method of fixing the nut to the bent surface 12a by welding or bonding, a method of using a press nut, or the like can be used.
(Blind rivet 51)

  In the above example, the fixture is constituted by a bolt, but the fixture is not limited to this, and other configurations, for example, rivets may be used. The rivet is fastened using plastic deformation of metal. Fixing with rivets is superior in reliability because there is no need for rotation such as screwing, no worry about loosening. The rivet is not limited to a normal rivet, and preferably a blind rivet can be used. A blind rivet is a special rivet that can be fastened from one side of a folding surface. FIG. 11 shows the appearance of the blind rivet 51. The blind rivet 51 includes a flange and a shaft (mandrel) inserted through the flange. By pulling up the shaft, the head of the rivet is crushed into a dumpling shape, and the state shown in FIG. 12 can be obtained. This method eliminates the need for large-scale equipment, and eliminates the need for receiving the lower side of the folding surface 12a, so that the folding surface 12a can be fastened very easily.

When the blind rivet 51 is used, the bending position is set so that the lower curved surface 12a becomes the electrode terminal 12 having higher strength than the upper side. Thereby, when connecting with the blind rivet 51, it is possible to prevent the shaft from entering. For example, in the case of a lithium ion battery using Al for the positive electrode terminal and Cu for the negative electrode terminal, the folding surface 12a of the high-strength negative electrode terminal is arranged on the lower side. In this case, the distance from the battery cell end surface is shortened by a sum of the thickness of the electrode terminal 12 and the thickness of the voltage detection terminal 70 relative to the positive electrode side (the height is less Adjust it to be lower).
(Elastic member 60)

  In addition, an elastic member such as a spring washer can be interposed as necessary to prevent the fixture FS from loosening. By interposing the elastic member 60 between the fixture FS and the folded curved surface 12a, the elastic member 60 presses the connecting surface to increase the frictional force, and a loosening prevention effect is obtained. The elastic member 60 is preferably formed on the connection surface 72 of the voltage detection terminal. This example will be described with reference to FIGS. In these drawings, FIG. 13 is an enlarged exploded perspective view showing a state in which the connecting portion of the voltage detection terminal 70B having such an elastic member 60B is fixed by the fixing tool FS, and FIG. 14 is a side view of FIG. 15 is an enlarged perspective view in a state where the voltage detection terminal 70B of FIG. 13 is fixed. In this example, the connection surface 72 provided with the detection terminal hole 71 of the voltage detection terminal 70B is formed in a spring washer shape, a frictional force is generated by the elastic force of the spring washer, and the blind rivet 51 which is the fixture FS. To prevent loosening. The spring washer shape can be formed integrally with the voltage detection terminal 70B. As a result, the number of parts can be reduced to reduce the cost, and the work for inserting the spring washer can be omitted even during assembly, thereby simplifying the work.

The elastic member 60 can also be configured as a separate member from the voltage detection terminal. When a spring washer is used as the elastic member, a large current is passed through the spring washer as described above by interposing the spring washer between the bent surfaces in the same manner as the voltage detection terminals, thereby suppressing the occurrence of electrolytic corrosion. Further, by inserting only the spring washer between the folded curved surfaces without inserting the voltage detection terminal between the folded curved surfaces, the electric corrosion can be similarly prevented. In particular, the spring washer is inexpensive and easy to manufacture, and it is possible to realize the prevention of loosening of the fixture and the prevention of electrolytic corrosion at a low cost.
(Embodiment 2)

  In the above example, only one connecting hole is formed on the bent surface, but two or more connecting holes can be opened. Thereby, the fastening structure by the fixture FS can be doubled or tripled to further increase the fastening force of the electrode terminal and improve the reliability. 16 to 19 show an example of the battery pack 200 according to Embodiment 2 that employs such a configuration. In these drawings, FIG. 16 is a perspective view of the battery pack 200, FIG. 17 is a side view of FIG. 16, FIG. 18 is an enlarged exploded perspective view showing a connecting portion by a fixture FS, and FIG. Respectively. In the example of the fixture FS shown in these drawings, the electrode terminal 12B is formed so that the plan view is L-shaped, and the folding surface 12b is extended in the longitudinal direction of the end surface of the battery cell. Two 13 and 13B are opened. As shown in FIG. 18, a blind rivet 51 is inserted through one connecting hole 13 as a fixture FS and a spring washer as an elastic member 60, and the blind rivet 51 is inserted into the other connecting hole 13B. Is inserted into the detection terminal hole 71 of the voltage detection terminal 70B integrated with the spring washer shape as the elastic member 60B and fastened in a co-tightened state. Thus, the fastening structure is doubled to increase the reliability, and the voltage detection terminal 70B is arranged on one side, so that the intermediate voltage can be detected.

As described above, the battery cells are connected to each other by bending the tip of each battery cell having the connection hole 13 opened at the tip of each electrode terminal 12 to form a bent surface 12a. The electrode terminals 12 of adjacent battery cells are fastened using the fixture FS with the voltage detection terminals 70 interposed between the electrode terminals 12 of adjacent battery cells in a state in which the end surfaces provided with are arranged in a substantially identical plane. Thereby, without using another member like a bus bar, the electrode terminals 12 of the adjacent battery cells can be brought into direct contact with each other to be electrically connected. In addition, a series of production steps up to fixing can be automated or semi-automated, and the production of the battery pack can be made efficient.
(Embodiment 3)

  On the other hand, it is not restricted to this, The structure which inserts the fixing tool FS in a horizontal direction with a battery cell end surface is also employable. As a battery pack according to Embodiment 3, an example of such a battery pack will be described with reference to FIGS. In these drawings, FIG. 20 is a perspective view showing a state in which battery cells 10B are connected to each other, and FIG. 21 is a side view. In the battery pack shown in these drawings, the battery cells 10B shown in FIG. 21 are stacked, and the electrode terminals 12C of the battery cells 10B are fixed with rivets. In the battery cell 10B, similarly to the battery cell 10 shown in FIG. 9 and the like, the positive electrode terminal 12C and the negative electrode terminal 12C are protruded from the upper end face at a symmetrical position. However, the electrode terminal 12C is bent so that the bent surface 12c at the end of the electrode terminal 12C is not parallel to the end surface of the battery cell 10B but is substantially vertical. Specifically, with each electrode terminal 12C being bent at two positions, the electrode terminal 12C is bent so as to protrude obliquely from the end face of the battery cell 10B by the first bending. At this time, each electrode terminal 12C is protruded in the opposite oblique direction. Further, the bent surface 12c is bent in a substantially vertical posture with respect to the end surface of the battery cell 10B by the second bending. At this time, the folding surface 12c is set to be substantially flush with the side surface of the battery cell 10B. Thereby, when battery cell 10B is laminated | stacked, the folding surface 12c of the positive electrode and negative electrode of adjacent battery cell 10B can be contact | abutted. Also in this configuration, the voltage detection terminal 70 is interposed between the folded curved surfaces 12c to similarly prevent electrolytic corrosion and avoid the deformation of the voltage detection terminal 70.

  The battery cell 10B is manufactured with the electrode terminal 12C protruding in a plate shape. After the battery cell 10B is manufactured, the electrode terminal 12C is bent and bent at two locations so as to extend in opposite oblique directions. Is done. The battery cells 10B are sequentially stacked, and the connection holes 13C are riveted and fixed. Riveting is done automatically by a riveting machine.

  The battery pack and the manufacturing method thereof according to the present invention can be suitably applied as a power supply device for a vehicle such as an electric vehicle or a hybrid vehicle.

1 is an external perspective view of a battery pack according to Embodiment 1 of the present invention. It is a perspective view of the battery cell laminated body which comprises the battery pack of FIG. It is an expansion perspective view which shows the electrode terminal part of the battery cell laminated body of FIG. It is a disassembled perspective view of the electrode terminal part of FIG. It is a top view of the battery cell laminated body 1 of FIG. It is a side view of the battery cell laminated body 1 of FIG. It is a front view of the battery cell laminated body 1 of FIG. It is a schematic cross section which shows a mode that it supplies with electricity to the electrode terminal of the battery cell laminated body of FIG. It is a perspective view of the battery cell which concerns on a modification. It is a perspective view of the battery cell which concerns on another modification. It is a perspective view which shows the external appearance of a blind rivet. It is sectional drawing of the folding surface of the electrode terminal fixed with the rivet. It is an expansion disassembled perspective view which shows the voltage detection terminal and electrode terminal part provided with an elastic member. FIG. 14 is a side view of FIG. 13. It is an expansion perspective view which shows the state which fixed the voltage detection terminal of FIG. 6 is a perspective view of a battery pack according to Embodiment 2. FIG. FIG. 17 is a side view of FIG. 16. It is an expansion disassembled perspective view which shows the connection part of FIG. It is an expansion perspective view which shows the fastening state of FIG. FIG. 9 is a perspective view showing a state where battery cells according to Embodiment 3 are connected to each other. It is a side view of the battery cell coupling body of FIG. It is a perspective view of the conventional battery pack. It is a perspective view of the battery cell laminated body which comprises the battery pack of FIG. It is an expansion perspective view which shows the electrode terminal part of the battery cell laminated body of FIG. It is a top view of the battery cell laminated body of FIG. It is a side view of the battery cell laminated body of FIG. It is a front view of the battery cell laminated body of FIG. It is a schematic cross section which shows a mode that it supplies with electricity to the electrode terminal of the battery cell laminated body of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200, 300 ... Battery pack 1 ... Battery cell laminated body 10, 10B, 10C, 10D ... Battery cell 12, 12B-12E ... Electrode terminal 12a-12c ... Folding curved surface 13, 13B-13C ... Connection hole 13D ... Burring part 13E ... nut portion 14 ... terminal rib 20 ... separator 30 ... end plate 32 ... screw hole 34 ... extension bolt 51 ... blind rivet 52 ... bolt 53 ... nut 60, 60B ... elastic member 70, 70B ... voltage detection terminal 71 ... detection Terminal hole 72 ... Connection surface FS ... Fixing tool

Claims (18)

A battery pack in which a plurality of battery cells are adjacent and connected in series with each other,
Positive and negative electrode terminals are projected from one end face, and a plurality of battery cells using metals with different ionization tendency in the positive electrode and the negative electrode,
A voltage detecting terminal having a connection surface for electrically connecting to the electrode terminal of the battery cell in order to measure the terminal voltage of the battery cell;
A fixture for fixing and connecting the positive and negative electrodes of adjacent battery cells in a state in which the battery cells are arranged with the end surfaces provided with electrode terminals aligned in substantially the same plane,
With
The connection surface of the voltage detection terminal is made of a metal having an ionization tendency intermediate between the ionization tendency of the metal constituting the positive electrode terminal and the ionization tendency of the metal constituting the negative electrode terminal,
The electrode terminal is formed in a plate shape, the plate electrode terminal protrudes upward from the end surface of the battery cell, has a bent curved surface by bending the tip,
The voltage detection terminals are connected to each other between the positive and negative electrode terminals of adjacent battery cells with the connection surface of the voltage detection terminal interposed therebetween, and are connected to the fixed state by the fixture. A battery pack characterized by A battery pack in which a plurality of battery cells are adjacent and connected in series with each other,
Positive and negative electrode terminals are projected from one end face, and a plurality of battery cells using metals with different ionization tendency in the positive electrode and the negative electrode,
A voltage detecting terminal having a connection surface for electrically connecting to the electrode terminal of the battery cell in order to measure the terminal voltage of the battery cell;
A fixture for fixing and connecting the positive and negative electrodes of adjacent battery cells in a state in which the battery cells are arranged with the end surfaces provided with electrode terminals aligned in substantially the same plane,
With
The connection surface of the voltage detection terminal has a difference in ionization tendency between the metal constituting the positive electrode and the negative electrode rather than the difference in ionization tendency between the metal constituting the positive electrode terminal and the metal constituting the negative electrode terminal. Composed of small metal,
The electrode terminal is formed in a plate shape, the plate electrode terminal protrudes upward from the end surface of the battery cell, has a bent curved surface by bending the tip,
The voltage detection terminals are connected to each other between the positive and negative electrode terminals of adjacent battery cells with the connection surface of the voltage detection terminal interposed therebetween, and are connected to the fixed state by the fixture. A battery pack characterized by The battery pack according to claim 1 or 2,
The battery cell is a lithium ion battery;
A battery pack, wherein the connection surface of the voltage detection terminal is Ni or Ni-Cr plated Cu or Ni. The battery pack according to any one of claims 1 to 3,
A connecting hole is formed in the bent surface of the electrode terminal,
On the connection surface of the voltage detection terminal, a detection terminal hole is formed with an inner diameter substantially equal to or larger than the connection hole,
The fixture includes an insertion body that is inserted through the connection hole,
The insertion body is configured to be penetrated in a direction substantially perpendicular to the end surface of the battery cell in a state where the bent surface of the positive and negative electrode terminals and the connection hole of the connection surface interposed therebetween are matched. A battery pack characterized by The battery pack according to any one of claims 1 to 3 ,
The battery cell is a prismatic battery;
The electrode terminal is bent so as to protrude obliquely from the end face of the battery cell, and the bent surface is bent in a posture substantially perpendicular to the end face of the battery cell, and is substantially flush with the side face of the prismatic battery cell. together formed by positioned,
A connecting hole is formed in the bent surface of the electrode terminal,
On the connection surface of the voltage detection terminal, a detection terminal hole is formed with an inner diameter substantially equal to or larger than the connection hole,
The fixture includes an insertion body that is inserted through the connection hole,
A battery pack , wherein the insertion body is configured to penetrate the connecting hole in a state where the bent surface of the positive and negative electrode terminals and the connecting hole of the connecting surface interposed therebetween are matched . The battery pack according to claim 5 ,
A battery pack, wherein a pair of electrode terminals protrudes from the end face of the battery cell so as to be spaced apart, and each electrode terminal protrudes obliquely in different directions. The battery pack according to any one of claims 1 to 4 ,
The battery cell is a prismatic battery;
The electrode terminal protrudes from the end surface of the battery cell in a substantially vertical direction, and the tip is bent into a substantially L-shaped cross section so as to be parallel to the end surface to form a horizontal folding surface. A battery pack configured to overlap curved surfaces and to be connected by the fixture. The battery pack according to claim 7 ,
The battery pack, wherein the pair of electrode terminals is bent in a direction in which one bending direction is opposite to the other bending direction. The battery pack according to any one of claims 1 to 8,
One bent position of the pair of electrode terminals is folded shorter than the bent position of the other electrode terminal by an amount corresponding to the sum of the thickness of the electrode terminal and the thickness of the voltage detection terminal. A battery pack characterized by being bent. The battery pack according to any one of claims 4 to 6 ,
The fixture includes a bolt and a nut;
A battery pack, wherein a bolt is inserted from one side into a connecting hole having a bent surface obtained by overlapping the bent surfaces of electrode terminals of adjacent battery cells, and the other is screwed into a nut and fixed. The battery pack according to any one of claims 4 to 6 ,
The fixture includes a bolt and a burring portion in which a thread groove is formed by burring a connection hole of one folding surface,
The folding surfaces of the electrode terminals of adjacent battery cells are overlapped so that the folding surface having the burring portion is positioned below, and a bolt is inserted from above the connecting hole and screwed into the screw groove of the burring portion. A battery pack characterized by being fixed. The battery pack according to any one of claims 4 to 6 ,
The fixture includes a bolt and a nut portion that fixes a nut so that the opening coincides with a connection hole of one folding surface,
Overlay the folding surfaces of the electrode terminals of adjacent battery cells so that the folding surface with the nut part is positioned below, and insert the bolt from above the connection hole and screw it into the nut part and fix it. The battery pack characterized by becoming. The battery pack according to any one of claims 1 to 12,
The connection surface of the voltage detection terminal has an elastic member,
A battery pack, wherein the elastic member is connected so as to be interposed between the electrode terminals. The battery pack according to any one of claims 1 to 12,
The battery pack, wherein the fixing member has an elastic member interposed on a contact surface with the electrode terminal. The battery pack according to claim 14, wherein
The battery pack, wherein the elastic member is a spring washer. The battery pack according to any one of claims 4 to 6 ,
Each folding surface has two or more connecting holes,
A battery pack comprising: a fixing tool penetrating through each of the connecting holes; and a fixing terminal penetrating the fixing tool with the detection terminal hole of the connection surface aligned with at least one of the connecting holes. The battery pack according to claim 16, wherein
In one connecting hole, an elastic member is placed and sandwiched between the fixture and the folding surface,
A battery pack, characterized in that a voltage detection terminal is disposed in another connecting hole and sandwiched between a fixture and a folding surface. A battery pack manufacturing method in which a plurality of battery cells are adjacent and connected in series with each other,
In a plurality of battery cells using metals with different ionization tendency at the positive electrode terminal and the negative electrode terminal, a connecting hole is opened at the tip of a pair of electrode terminals protruding upward from the end face, and the tip is bent and folded. Forming a curved surface;
The metal of which the connection surface for electrically connecting with the electrode terminal of a battery cell of the voltage detection terminal for measuring the terminal voltage of a battery cell comprises the electrode terminal of a positive electrode, and the electrode terminal of a negative electrode The difference between the ionization tendency and the metal constituting the positive electrode and the negative electrode is smaller than the difference in ionization tendency,
In the state where the battery cells are arranged in a state where the end surfaces provided with the electrode terminals are substantially aligned on the same plane, the voltage detection terminal is connected between the bent surfaces of the positive electrode electrode and the negative electrode terminal of the adjacent battery cell. Overlaying these with the connection surface interposed, and connecting them in a fixed state with a fixture;
The manufacturing method of the battery pack characterized by including.

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