JP2015187910A - Battery pack and electric vehicle including the same and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To electrically connect an electrode terminal of a battery cell with a bus bar reliably and stably, while reducing the manufacturing cost of the bus bar.SOLUTION: In a battery pack, a bus bar 3 of a metal plate is fixed to an electrode terminal 2 of a plurality of battery cells, and this bus bar 3 connects the battery cells in series and/or parallel. The bus bar 3 has a plurality of through holes 38 for inserting the electrode terminals 2 of a plurality of battery cells to be connected. The through hole 38 is larger than the outer shape of the electrode terminal 2, a play gap 39 is provided between the through hole 38 and electrode terminal 2, and a gap through hole 38A into which the electrode terminal 2 can be inserted while being misaligned is provided. A fixing ring is inserted over the electrode terminal 2 inserted into the gap through hole 38A, and connects the electrode terminal 2 electrically with the bus bar 3. Furthermore, the bus bar 3 is a portion of the entire surface, a plating layer 34 is provided on the surface facing the fixing ring, and the fixing ring is connected electrically with the plating layer 34 on the bus bar surface.

Description

  The present invention relates to a battery pack in which a plurality of battery cells are connected in series with a bus bar, and more particularly to a battery pack in which a bus bar is metal-plated, an electric vehicle including the battery pack, and a power storage device.

  The battery pack can connect a plurality of battery cells in series to increase the output voltage and increase the output. In this battery pack, metal plate bus bars are connected to electrode terminals of a plurality of battery cells by a method such as welding, and the battery cells are connected in series with the bus bars. In this battery pack, through holes are provided at both ends of the bus bar, electrode terminals of battery cells are inserted into the through holes, and laser is irradiated to the boundary between the electrode terminals and the through holes to be electrically connected. This connection structure can electrically connect the electrode terminal and the bus bar in a low resistance state. In this connection structure, if there is a gap between the through hole of the bus bar and the electrode terminal, stable welding cannot be performed. For this reason, it is necessary to make the inner shape of the through hole and the outer shape of the electrode terminal substantially equal and insert the electrode terminal into the through hole. By the way, the bus bar which connects two battery cells in series needs to provide two through holes at both ends and insert the electrode terminals of the battery cells adjacent to each through hole. This bus bar is provided with two through holes at an interval equal to the interval between the opposing electrode terminals of adjacent battery cells. However, the interval between the electrode terminals of adjacent battery cells is not always constant and there is an error. If the distance between the two electrode terminals connected by the bus bar changes due to the dimensional error of the battery cell and is not equal to the distance between the two through holes of the bus bar, the two electrode terminals cannot be inserted into each through hole, Or even if it can be inserted, an unreasonable stress acts on the electrode terminal of the battery cell and its mounting portion.

  In order to prevent this problem, as shown in FIG. 1, the through hole 204A of the bus bar 203 is made larger than the outer shape of the electrode terminal 202, and the electrode terminal 202 is connected to the bus bar via a welding ring 206 inserted into the electrode terminal 202. A connecting structure that connects to 203 has been developed. (See Patent Document 1)

JP 2011-60623 A

  In the connection structure of FIG. 1, the inner shape of the through hole 204 </ b> A is larger than the outer shape of the electrode terminal 202, so that the relative positions of the electrode terminal 202 and the bus bar 203 are shifted to the through holes 204 at both ends of the bus bar 203. The electrode terminals 202 of the two battery cells 201 can be inserted. However, since this connection structure has a gap between the through hole 204A and the electrode terminal 202, the welding ring 206 is inserted into the electrode terminal 202 in order to eliminate this gap. The welding ring 206 has an inner shape equal to the outer shape of the electrode terminal 202 and can be placed on the bus bar 203 to eliminate a gap between the electrode terminal 202 and the bus bar 203. The welding ring 206 laser welds the inner periphery to the electrode terminal 202 and laser welds the outer periphery to the surface of the bus bar 203 to electrically connect the electrode terminal 202 to the bus bar 203. The weld ring 206 needs to have an outer shape larger than the inner shape of the through hole 204A in order to close the through hole 204A larger than the electrode terminal 202. In particular, the weld ring 206 has a considerably larger outer shape than the through hole 204A so that the through hole 204A can always be closed even if it is inserted into the electrode terminal 202 and the relative position between the electrode terminal 202 and the bus bar 203 changes. doing.

  By the way, the electrode terminal is not necessarily welded and connected to the bus bar. FIG. 2 shows a connection structure for fixing the electrode terminal 302 to the bus bar 303 via the nut 307. In this connection structure, a male screw is provided on the surface of the electrode terminal 302. The electrode terminal 302 is inserted into the through hole 304 of the bus bar 303, a nut 307 is screwed into the male screw of the electrode terminal 302, and the nut 307 fixes the electrode terminal 302 to the bus bar 303. In this connection structure, the electrode terminal 302 can be electrically connected to the bus bar 303 while the through hole 304 is enlarged and the relative position between the electrode terminal 302 and the bus bar 303 is adjusted.

  The weld ring and nut connection structure improves the welding characteristics by providing a plating layer such as nickel plating on the surface of the bus bar, prevents corrosion of the contact surface to be electrically connected, and prevents contact failure over a long period of time. Can be prevented. However, a bus bar having a plating layer on the entire surface not only increases the manufacturing cost, but depending on the type of battery cell, if a plating layer is provided on the entire surface of the bus bar, it may not be possible to stably weld the electrode terminal of the battery cell. There is. For example, since a lithium ion battery has a positive electrode terminal made of aluminum, the portion connected to the positive electrode terminal of the bus bar is made of an aluminum plate, but if the surface of the aluminum plate is nickel-plated, it is welded to the electrode terminal made of aluminum. It becomes difficult. This is because an alloy of nickel and aluminum is formed during welding, and this alloy deteriorates the contact state.

  The present invention has been developed for the purpose of solving the above-mentioned drawbacks. An important object of the present invention is to provide a battery pack that can reliably and electrically connect the electrode terminals of the battery cells and the bus bar while reducing the manufacturing cost of the bus bar, an electric vehicle including the battery pack, and a power storage device. is there.

Means for Solving the Problems and Effects of the Invention

  In the battery pack of the present invention, a metal plate bus bar 3 is fixed to electrode terminals 2 and 52 of a plurality of battery cells 1 and 51, and the bus bar 3 connects the battery cells 1 and 51 in series and / or in parallel. Yes. The bus bar 3 has a plurality of through holes 38 into which the electrode terminals 2 and 52 of the battery cells 1 and 51 to be connected are inserted. The through hole 38 is larger than the outer shape of the electrode terminals 2 and 52, and there is a play gap 39 between the through hole 38 and the electrode terminals 2 and 52, so that the electrode terminals 2 and 52 can be inserted while being displaced. It has a hole 38A. A fixing ring 7 is inserted into the electrode terminals 2 and 52 inserted into the clearance through hole 38 </ b> A, and the fixing ring 7 electrically connects the electrode terminals 2 and 52 to the bus bar 3. Further, the bus bar 3 is a part of the entire surface, and a plating layer 34 is provided on the surface facing the fixing ring 7, and the fixing ring 7 is electrically connected to the plating layer 34 on the surface of the bus bar.

  The battery pack described above has a feature that the electrode terminal of the battery cell and the bus bar can be reliably and stably electrically connected while reducing the manufacturing cost of the bus bar. The above battery pack is provided with a plating layer on the surface facing the fixing ring inserted into the electrode terminal inserted through the gap through hole without providing a plating layer on the entire surface of the bus bar. This is because the fixing ring inserted into the electrode terminal inserted through the electrode is brought into contact with the plating layer of the bus bar.

  In addition, the above battery pack reduces the plating area of the bus bar and reduces the plating cost, while ensuring stable and reliable electrical connection between the battery cell electrode terminals and bus bars with different positive and negative electrode terminal materials. Features that can be realized. This is because the above battery pack has a structure in which a plating layer is not provided on the entire surface of the bus bar, and a plating layer is not provided in a region where the plating layer obstructs the electrical connection between the electrode terminal and the bus bar.

  Moreover, the above battery cell can prevent the corrosion of the area | region where a bus-bar is electrically connected to a fixing ring by the plating layer on the bus-bar surface. For this reason, the electrode terminal is electrically connected to the bus bar via the fixing ring stably for a long period of time.

  In the battery pack of the present invention, the fixing ring 7 is a welding ring 7A, the welding ring 7A is a metal plate made of the same material as the plating layer 34, or the same metal plate as the bus bar 3 is provided with the same plating layer as the bus bar 3 on the surface. Can be provided. The fixing ring 7 which is a welding ring 7A can be electrically connected to the bus bar 3 by laser welding the inner peripheral edge to the electrode terminal 2 and laser welding the outer peripheral edge to the plating layer 34 on the bus bar surface. .

  The battery pack described above is in a state where the electrode terminal and the bus bar are connected in a range of misalignment, and the welding ring and the metal of the bus bar are welded while being an optimal metal material that can be electrically connected to the bus bar in a preferable state. There is a feature that the ring can be stably and reliably laser welded to the bus bar. The bus bar and the weld ring are made of the same metal, thereby preventing adverse effects such as electric corrosion and being electrically connected in a preferable state. However, it is not always possible to perform laser welding in a preferable state using the same metal as the bus bar and the welding ring. For example, although a bus bar and a welding ring are used as a copper plate, electrical connection can be prevented and electrical connection can be made in a preferable state. The same plating layer is provided on the welding ring and the bus bar, or the welding ring is made of the same metal plate as the plating layer of the bus bar to prevent the reflection of the laser beam, so that the welding ring and the bus bar can be reliably and laser welded. For this reason, the above battery pack can be laser-welded in a preferable state while electrically connecting the welding ring and the bus bar in a preferable state. Moreover, corrosion of the weld ring and the bus bar can be prevented by the material and the plated layer of the weld ring and the plated layer of the bus bar. In particular, it is possible to prevent the corrosion of the region where the welding ring and the bus bar are electrically connected in the vicinity of the laser welding, and to stably connect the electrode terminal to the bus bar for a long period of time.

The battery pack of the present invention has the fixing ring 7 as a nut 7B, the same plating layer as the bus bar 3 is provided on the surface of the nut 7B, and the male screw 54 to which the nut 7B is screwed is fixed to the electrode terminal 52. The nut 7B is screwed into the male screw 54 of the electrode terminal 52, and the plating layer on the surface of the nut is brought into contact with the plating layer 34 on the surface of the bus bar, so that the electrode terminal 52 can be electrically connected to the bus bar 3 via the nut 7B.
The battery cell described above is characterized in that the nut and the bus bar can be electrically connected stably over a long period of time while the electrode terminal and the bus bar are connected in a position shift range.

In the battery pack of the present invention, the battery cells 1 and 51 are lithium ion batteries in which the positive terminals 2A and 52A are made of aluminum and the negative terminals 2B and 52B are made of copper, the bus bar 3 is joined to the aluminum plate 31 and the copper plate 32. As a metal clad material 30, a plated layer 34 can be provided on the surface of the copper plate 32. In this battery pack, the positive terminals 2A, 52A of the battery cells 1, 51 are electrically connected to the aluminum plate 31 of the bus bar 3, and the negative terminals 2B, 52B are electrically connected to the copper plate 32 of the bus bar 3, and are inserted into the through holes 38 of the copper plate 32. The negative electrodes 2B and 52B thus made can be electrically connected to the copper plate 32 via the fixing ring 7.
However, in this specification, “aluminum plate” is used in a broad sense including an aluminum alloy plate, and “copper plate” is used in a broad sense including a copper alloy plate.
The battery cell described above is characterized in that a lithium ion battery having a positive electrode terminal made of aluminum and a negative electrode terminal made of copper can be electrically connected to a preferable state with a bus bar. This is because the positive electrode terminal made of aluminum is electrically connected to a bus bar without a plating layer, and the electrode terminal made of copper is electrically connected to a copper plate of the bus bar provided with the plating layer via a fixing ring.

In the battery pack of the present invention, the plating layer 34 of the bus bar 3 can be nickel-plated, and the fixing ring 7 can be a nickel-plated welding ring 7A.
In the above battery pack, the welding ring of the nickel plate can be stably and reliably laser-welded to the nickel plating layer on the surface of the bus bar. This is because the nickel plate of the fixing ring and the nickel plating layer of the bus bar prevent laser beam reflection and can be laser welded. Further, there is a feature that corrosion of the fixing ring and the bus bar can be prevented over a long period of time by nickel plating on the fixing ring of the nickel plate and the surface of the bus bar.

  In the battery pack of the present invention, the battery cell 1 is a square battery, and the square battery is fixed in a laminated state to form a battery laminate 9, and the electrode terminal 2 of the battery cell 1 of the battery laminate 9 is connected to the bus bar 3. Can be connected in series and / or in parallel.

In the battery pack of the present invention, the fixing ring 7 is a welding ring 7A, and a play gap 39 is formed between the close contact through hole 38B where the bus bar 3 contacts the outer peripheral surface of the electrode terminal 2 and the inner peripheral surface of the electrode terminal 2. The electrode terminal 2 having a gap through-hole 38A that can be inserted by shifting the position of the electrode terminal 2 is laser-welded between the electrode terminal 2 and the close-contact through-hole 38B. The electrode terminal 2 to be electrically connected and inserted into the clearance through hole 38A is welded via a welding ring 7A formed by laser welding the inner peripheral edge to the electrode terminal 2 and laser welding the outer peripheral edge to the plating layer 34 of the bus bar 3. The bus bar 3 can be electrically connected.
Since the above battery pack is connected by welding the electrode terminal directly to the close-through hole of the bus bar while welding the electrode terminal to the gap through-hole of the bus bar via the weld ring, the gap through-hole Thus, the electrode terminal can be easily welded to the bus bar while absorbing the dimensional error between the electrode terminals of the battery cell. In particular, the electrode terminal can be directly welded to the close-through hole of the bus bar without using a welding ring.

The battery pack of the present invention includes a voltage detection circuit 21 that detects the voltage of the battery cell 1, and a voltage detection terminal 23 is connected to the plating layer 34 of the bus bar 3, and a lead wire 22 is connected to the voltage detection terminal 23. Thus, the voltage detection terminal 23 of the battery cell 1 can be connected to the voltage detection circuit 21 via the lead wire 22.
The above battery pack can detect the voltage of a battery cell correctly over a long period of time with a voltage detection circuit by electrically connecting the electrode terminal to the bus bar stably.

  The electric vehicle of the present invention includes any one of the battery packs 100 described above, a traveling motor 93 supplied with power from the battery pack 100, a vehicle main body 90 on which the battery pack 100 and the motor 93 are mounted, and a motor. And a wheel 97 for driving the vehicle main body 90.

  The power storage device of the present invention includes any one of the battery packs 100 described above and a power supply controller 84 that controls charging / discharging of the battery pack 100. The power supply controller 84 can charge the battery pack 100 with external power and can control the battery pack 100 to be charged.

It is a perspective view of the battery pack concerning one embodiment of the present invention. It is a disassembled perspective view of the battery pack shown in FIG. It is a block diagram of the battery pack concerning one embodiment of the present invention. It is a vertical longitudinal cross-sectional view which shows the internal structure of a battery cell. It is a longitudinal cross-sectional view which shows an example of a bus bar. It is a longitudinal cross-sectional view which shows another example of a bus bar. It is a top view which shows a bus bar and a voltage detection terminal. It is a disassembled perspective view which shows the process of connecting an adjacent electrode terminal with a bus bar. It is a perspective view which shows the connection structure of the electrode terminal shown in FIG. 8, and a bus bar. It is an expanded sectional view showing other examples which connect the electrode terminal which adjoins with a bus bar. It is a disassembled perspective view which shows another example which connects the adjacent electrode terminal with a bus bar. It is a block diagram which shows the example which mounts a battery pack in the hybrid car which drive | works with an engine and a motor. It is a block diagram which shows the example which mounts a battery pack in the electric vehicle which drive | works only with a motor. It is a block diagram which shows the example which uses a battery pack for an electrical storage apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a battery pack for embodying the technical idea of the present invention, an electric vehicle including the battery pack, and a power storage device, and the present invention includes a battery pack and an electric motor including the battery pack. The vehicle and the power storage device are not specified as follows. Moreover, the member shown by the claim is not what specifies the member of embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof 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. In addition, the contents described in some examples and embodiments may be used in other examples and embodiments.

  FIGS. 3 to 5 are power sources that are mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle as a battery pack according to an embodiment of the present invention to supply electric power to a vehicle running motor and cause the vehicle to run. The battery pack 100 used for is shown. The battery pack 100 shown in these drawings is connected to a battery stack 9 formed by stacking a plurality of battery cells 1 having electrode terminals 2 and the electrode terminals 2 of adjacent battery cells 1 so that the battery cells 1 are connected in series. The bus bar 3 is connected, a lead wire 22 connected to the voltage detection terminal 23 of the bus bar 3, and a voltage detection circuit 21 connected to the battery cell 1 via the lead wire 22.

  The battery stacked body 9 insulates a plurality of battery cells 1 from each other and fixes them in a stacked state. The battery laminate 9 has end plates 4 disposed at both ends thereof. The pair of end plates 4 are connected by a connector 5 to fix the battery stack 9 in a stacked state.

  The battery cell 1 is a square battery. Furthermore, the battery cell 1 is a lithium ion battery. In the lithium ion battery, the positive electrode terminal 2A is made of aluminum, and the negative electrode terminal 2B is made of copper. However, the battery pack of the present invention can use a cylindrical battery cell without specifying the battery cell as a rectangular battery. Moreover, it is not specified also as a lithium ion battery, For example, a nickel-water battery etc. can be used. As shown in FIG. 6, the battery cell 1 houses an electrode body 10 in which positive and negative electrode plates are stacked in an outer can 11 and is filled with an electrolyte (not shown), and the opening is a sealing plate 12. It is hermetically sealed. The illustrated outer can 11 is formed into a square cylinder that closes the bottom, and the upper opening is airtightly closed by the sealing plate 12. Moreover, between the battery cells 1 can be insulated by interposing an insulating spacer 6 as necessary.

  The outer can 11 is obtained by deep drawing a metal plate such as aluminum and has a conductive surface. The battery cells 1 to be stacked are formed into thin squares. The sealing plate 12 is made of a metal plate such as aluminum which is the same metal as the outer can 11. The sealing plate 12 has positive and negative electrode terminals 2 fixed to both ends via an insulating material 13. The positive and negative electrode terminals 2 are connected to built-in positive and negative electrode plates. The lithium ion battery does not connect the outer can 11 to the electrode. However, since the outer can 11 is connected to the electrode plate via the electrolytic solution, it has an intermediate potential between the positive and negative electrode plates. However, a battery cell can also connect one electrode terminal to an armored can with a lead wire. The battery cell can be fixed to the sealing plate without insulating the electrode terminal connected to the outer can.

  In the battery pack 100, a plurality of battery cells 1 are stacked to form a rectangular parallelepiped block-shaped battery stack 9. The battery cell 1 is formed into a block shape by laminating the surface on which the electrode terminal 2 is provided, in FIG. 4, the sealing plate 12 so as to be on the same plane. In the battery pack 100 of FIG. 4, the electrode terminal 2 is disposed on the upper surface of the block. The battery pack 100 is laminated in a state in which the positive and negative electrode terminals 2 at both ends of the sealing plate 12 are reversed left and right. In this battery pack 100, as shown in the figure, the electrode terminals 2 adjacent on both sides of the block are connected by a bus bar 3, and the battery cells 1 are connected in series. Both ends of the bus bar 3 are connected to the positive and negative electrode terminals 2 to connect the battery cells 1 in series. In the illustrated battery pack 100, the battery cells 1 are connected in series to increase the output voltage. However, in the battery pack of the present invention, the battery cells are connected in series and in parallel to increase the output voltage and output current. You can also

  The electrode terminal 2 is fixed to the sealing plate 12 via an insulating material 13 and has a cylindrical or columnar tip portion. The electrode terminal is connected to the bus bar 3 by being inserted into a through hole 38 provided in the bus bar 3 in a columnar shape, a polygonal column shape, or a shape in which a ring is provided so as to protrude outward from the upper end surface.

  The bus bar 3 is provided with through holes 38 into which the electrode terminals 2 are inserted at both ends connected to the electrode terminals 2 of the plurality of battery cells 1. In the battery pack of FIG. 4, two battery cells 1 that are stacked adjacent to each other are connected in series by a bus bar 3, so that two through holes 38 are provided at both ends of the bus bar 3. The bus bar 3 does not necessarily connect two battery cells 1 in series, but may connect, for example, four battery cells in series and in parallel. This bus bar is provided with four through holes. The bus bar 3 in FIG. 4 connects the battery cells 1 of the stacked battery stack 9 in series. However, the bus bar can be connected in series with battery cells arranged at predetermined positions by a battery holder (not shown). This bus bar has a through hole at the position of the electrode terminal of the battery cell.

  As shown in FIGS. 7 and 8, the bus bar 3 has the interval between the through holes 38 equal to the interval between the electrode terminals 2 of the battery cells 1 arranged at a predetermined position. This is because the electrode terminal 2 of each battery cell 1 is inserted into the through hole 38 and the electrode terminal 2 is electrically connected to the bus bar 3. Unfortunately, the interval between the electrode terminals 2 of the battery cells 1 arranged at a predetermined position is not always constant. Due to the dimensional error of the battery cell 1 and the dimensional error of the battery holder, an error is generated in the distance between the electrode terminals 2. In order to insert the electrode terminal 2 whose interval changes, the bus bar 3 has one or both through-holes 38 enlarged, and a play gap 39 is provided between the bus bar 3 and the electrode terminal 2. The bus bar 3 has a large through hole 38 to provide a position shift range so that the electrode terminal 2 can be inserted into the through hole 38 in a state where the relative positions of the electrode terminal 2 and the bus bar 3 are shifted.

  The bus bar 3 shown in FIGS. 7 and 8 has one through hole 38 extending in the stacking direction of the battery cell 1 so that the electrode terminal 2 of the battery cell 1 can be inserted into the through hole 38 even when the electrode terminal 2 is shifted in the stacking direction. As the hole shape, a misalignment range is provided. Even when the electrode terminals 2 of the battery cells 1 are displaced in the stacking direction due to a dimensional error of the battery cells 1, the bus bars 3 can be smoothly and easily inserted into the through holes 38. The positional deviation range in which the plurality of electrode terminals 2 can be inserted into the respective through holes 38 by absorbing the dimensional error of the interval between the electrode terminals 2 is, for example, shifted relative position between the electrode terminal 2 and the bus bar 3 by 0.5 mm to 3 mm. Thus, the electrode terminal 2 is set in a range where the electrode terminal 2 can be inserted into the through hole 38 of the bus bar 3. The position shift range is specified by a dimensional difference between the inner shape of the through hole 38 and the outer shape of the electrode terminal 2.

  In the bus bar 3, a plurality of electrode terminals 2 having dimensional errors are inserted into the through holes 38, so that the play holes 39 are provided by making the through holes 38 larger than the electrode terminals 2. The bus bar can be provided with play gaps between all the through holes and the electrode terminals. However, the bus bar 3 can also be provided with a close-contact through hole 38 </ b> B having no play gap 39 between the electrode terminal 2 and a gap through hole 38 </ b> A with a play gap 39 between the electrode terminal 2. The bus bar 3 has at least one through hole 38 as a close-contact through hole 38B and the other through hole 38 as a clearance through hole 38A.

  7 and 8 are connected to the electrode terminals 2 of the battery cells 1 stacked on each other. Therefore, one through hole 38 is used as a close contact hole 38B, and the other through hole 38 is used as the battery cell 1. A long-hole-shaped gap through hole 38A extending in the stacking direction is used. The bus bar 3 can smoothly and easily insert the electrode terminal 2 into the clearance through hole 38 </ b> A even if the interval between the electrode terminals 2 is shifted in the stacking direction of the battery cells 1.

  As shown in FIG. 9, the play gap 39 between the through hole 38 and the electrode terminal 2 is closed by the fixing ring 7 inserted into the electrode terminal 2. The fixing ring 7 has an inner shape equal to the outer shape of the electrode terminal 2, and the outer shape is larger than the inner shape of the through hole 38. In particular, the outer shape of the fixing ring 7 is designed such that the gap through hole 38A can be closed regardless of the position of the electrode terminal 2 inserted into the gap through hole 38A. The fixing ring 7 connected to the bus bar 3 by laser welding is a welding ring 7A. The weld ring 7A is made of the same metal plate as the plated layer 34 of the bus bar 3 to be described later, or is the same or different metal plate as the bus bar 3, and the same plated layer as the plated layer 34 of the bus bar 3 is provided on the surface. A metal plate is used. The welding ring 7A welded to the bus bar 3 having the plating layer 34 as a nickel plating layer is made of a nickel plate or a metal plate whose surface is nickel-plated. The welding ring 7A provided with the same plating layer as the plating layer 34 provided on the bus bar 3 on the surface is preferably manufactured from the same metal plate as the bus bar 3, but is not necessarily required to be the same metal plate as the bus bar 3. It can also be made of other metal plates.

  The bus bar 3 is provided with a plating layer 34 on the surface in order to reliably connect the fixing ring 7 and to stably connect the fixing ring 7 over a long period of time. The plated layer 34 is not provided on the entire surface of the bus bar 3. The bus bar 3 is provided with a plating layer 34 on the surface facing the fixing ring 7. The fixing ring 7 is inserted into the electrode terminal 2 that is inserted into the clearance through hole 38A. The electrode terminal 2 inserted through the clearance through hole 38A is not inserted into the fixed position of the clearance through hole 38A. This is because the clearance through hole 38A is provided with a play gap 39 so that the electrode terminal 2 can be inserted in a state of being displaced. Accordingly, the position of the fixing ring 7 facing the bus bar surface changes depending on the position where the electrode terminal 2 is inserted into the clearance through hole 38A. The bus bar 3 is provided with a plating layer 34 in all regions facing the fixing ring 7 inserted through the electrode terminal 2 in any state where the electrode terminal 2 is inserted through the gap through hole 38A. The bus bar 3 in FIG. 7 is provided with a plating layer 34 in a region larger than the outer shape of the fixing ring 7. Further, in the bus bar 3 in this figure, the plating layer 34 is also expanded to the area where the voltage detection terminal 23 is soldered.

  The bus bar 3 in FIG. 7 is connected to the positive electrode terminal 2A and the negative electrode terminal 2B of the lithium ion battery, and is a clad material 30 that press-contacts the aluminum plate 31 and the copper plate 32. Since the lithium ion battery has the positive electrode terminal 2A made of aluminum and the negative electrode terminal 2B made of copper, the bus bar 3 electrically connects the aluminum plate 31 to the positive electrode terminal 2A and the copper plate 32 to the negative electrode terminal 2B. In this bus bar 3, a plated layer 34 is provided on the surface facing the fixing ring 7 on the surface of the copper plate, with the through hole 38 of the aluminum plate 31 as a close-contact through hole 38B and the through hole 38 of the copper plate 32 as a gap through hole 38A. . Since the close contact through hole 38B provided in the aluminum plate 31 is in close contact with the outer periphery of the electrode terminal 2, the positive electrode terminal 2A made of aluminum and the aluminum plate 31 of the bus bar 3 are directly welded without using the fixing ring 7. Electrically connected to The copper plate 32 of the bus bar 3 is electrically connected to the electrode terminal 2 through the fixing ring 7. The welding ring 7A, which is the fixing ring 7, is inserted into the electrode terminal 2 inserted through the clearance through hole 38A, the inner peripheral edge is laser-welded to the electrode terminal 2, and the outer peripheral edge is laser-welded to the plating layer 34 on the bus bar surface. Electrical connection is made to the terminal 2 and the bus bar 3.

  The copper plate 32 of the bus bar 3 can be provided with a plating layer 34 on the surface facing the fixing ring 7, and the plating layer 34 can increase the absorption rate of the laser beam. Since the nickel plating can reduce the reflection of the laser beam, the laser beam can be efficiently absorbed and the fixing ring 7 can be efficiently laser-welded to the plating layer 34 of the bus bar 3. Therefore, the bus bar 3 can be laser-welded to the copper plate 32 efficiently by providing the plating layer 34 on the surface of the copper plate facing the fixing ring 7. The bus bar 3 can be provided with a plated layer 34 only on the surface of the copper plate facing the fixing ring 7, or the plated layer 34 can be provided on almost the entire surface of the copper plate 32. Further, as shown in FIG. 10, the battery cell 1 is provided with a mounting portion 18 of the bus bar 3 on the electrode terminal 2, and the mounting portion 18 is made of metal and is electrically connected to the electrode terminal 2. 7 can be fixed with the bus bar 3 interposed therebetween. The bus bar 3 is provided with a plating layer 34 on the contact surface with the mounting portion 18 on the back surface, and prevents corrosion by the plating layer 34, so that the electrical connection with the mounting portion 18 of the electrode terminal 2 can be made more stable.

  Furthermore, as shown in FIG. 11, the fixing ring 7 can also use a nut 7B instead of the welding ring 7A. In the battery pack in which the fixing ring 7 is the nut 7B, the male terminal 54 is provided in the electrode terminal 52 of the battery cell 51, inserted into the through hole 38 of the bus bar 3, and the nut 7B is screwed into the tip of the electrode terminal 52. Connected to bus bar 3. In this fixing ring 7, a nut 7 </ b> Ba screwed into the positive electrode terminal 52 </ b> A is made of the same metal as the aluminum plate 31 of the bus bar 3, that is, aluminum, and a plated layer 34 provided with a nut 7 </ b> Bb screwed into the negative electrode terminal 52 </ b> B on the copper plate 32. Can be made of the same metal, or can be made of a metal having the same plating layer as the plating layer 34 provided on the copper plate 32 on the surface. For example, the nut 7Bb connected to the nickel plating layer 34 provided on the copper plate 32 of the bus bar 3 can be made of nickel or made of metal whose surface is nickel-plated. The nut 7Bb provided with the same plating layer as the plating layer 34 provided on the copper plate 32 on the surface is preferably made of copper, but is not necessarily made of the same metal as the copper plate 32, and may be made of other metals. it can.

  The above-mentioned bus bar 3 is immersed in a plating solution in a state in which a region not to be plated is masked, and a plating layer 34 such as nickel plating is provided only in a necessary region.

  Further, the battery cell 1 shown in FIG. 6 has a current interrupt device 15 (Current Interrupt Device) built in the outer can 12 whose opening is closed by the sealing plate 12. The battery cell 1 shown in the figure has a current interruption mechanism 15 connected to the positive electrode terminal 2A. In the illustrated battery cell 1, a current interruption mechanism 15 is connected between a current collector 14 connected to an electrode body 10 and a positive electrode terminal 2 </ b> A fixed to a sealing plate 12. The on-state current interruption mechanism 15 connects the current collector 14 to the positive electrode terminal 2A. When the current interrupting mechanism 15 is turned off, the current collector 14 is not connected to the positive electrode terminal 2A, and the current of the battery cell 1 is interrupted. The current interrupting mechanism 15 includes a deformed metal plate 16 that is deformed by the internal pressure of the battery cell 1 and a connecting metal 17 that is formed by welding and locally connecting local portions of the deformed metal plate 16. When the internal pressure of the battery cell 1 becomes higher than the set pressure, the current interruption mechanism 15 deforms the deformed metal plate 16 with the pressure and separates the deformed metal plate 16 from the connection metal 17 to interrupt the current. In the battery cell 1, when the internal pressure of the battery cell 1 becomes higher than the set pressure, the current interruption mechanism 15 cuts off the current and can improve safety. However, the battery pack does not necessarily need to incorporate a current interruption mechanism in the battery cell. This is because a safety valve that opens at a set pressure can be provided on the sealing plate to prevent the internal pressure from rising abnormally.

  Furthermore, the battery cell 1 of FIG. 6 is provided with a safety valve 19 on the sealing plate 12 that closes the opening of the outer can 11. The safety valve 19 opens when the internal pressure of the battery becomes higher than a set value, and prevents the outer can 11 from being damaged or the connecting portion between the outer can 11 and the sealing plate 12 from being damaged. In the battery cell 1 including both the safety valve 19 and the current cutoff mechanism 15, the valve opening pressure at which the safety valve 19 opens due to the increase in the internal pressure of the battery is set higher than the current cutoff pressure at which the current cutoff mechanism 15 cuts off the current. ing. That is, when the internal pressure of the battery cell 1 rises and becomes larger than the current interruption pressure, the deformed metal plate 16 of the current interruption mechanism 15 is deformed by the internal pressure of the battery and separated from the connection metal 17, and the current of the battery cell 1 is increased. Shut off. In this state, the battery cell 1 is secured with safety by cutting off the current. Further, when the internal pressure of the battery rises from the state where the current interrupting mechanism 15 interrupts the current and becomes greater than the opening pressure of the safety valve 19, the safety valve 19 is opened and the internal gas is discharged to the outside. This prevents the internal pressure of the air from rising abnormally.

  Further, the battery pack 100 shown in FIGS. 3 and 4 has a surface plate 8 disposed on the upper surface of the battery stack 9, and the end surface of the battery cell 1 stacked on the surface plate 8 on the sealing plate 12 side. (Upper surface in the figure) is covered. The surface plate 8 is formed in an outer shape along the upper surface of the battery stack 9. The surface plate 8 is formed of an insulating plastic such as nylon resin or epoxy resin. Further, as shown in FIGS. 3 and 4, the surface plate 8 is provided with an opening window 29 for exposing the electrode terminal 2 of the battery cell 1 and connecting it to the bus bar 3. The illustrated surface plate 8 is provided with a plurality of opening windows 29 along both side portions of the battery stack 9. The opening window 29 is sized and shaped along the outer shape of the bus bar 3 so that it can be connected to the electrode terminal 2 while guiding the bus bar 3 to a fixed position. The bus bar 3 disposed in the opening window 29 of the surface plate 8 is fixed to the electrode terminal 2 of the battery cell 1 by welding such as laser welding, and connects the plurality of battery cells 1 to a predetermined connection state. However, it is not always necessary for the battery pack to dispose a surface plate on the upper surface of the battery stack.

  Furthermore, as shown in FIG. 5, the battery pack 100 includes a voltage detection circuit 21 that detects the voltage of each battery cell 1. 3 and FIG. 4, the circuit board 20 is fixed above the surface plate 8, and an electronic component (not shown) for realizing the voltage detection circuit 21 is mounted on the circuit board 20. . The voltage detection circuit 21 detects the voltage of each battery cell 1 and controls the charge / discharge current so as to prevent overcharge and overdischarge of each battery cell 1. The voltage detection circuit 21 is connected to the bus bar 3 that connects the electrode terminals 2 of the battery cells 1 through lead wires 22 that are voltage detection lines. The voltage detection circuit 21 connects the lead wire 22 connected to the input side to the bus bar 3, and detects the voltage of each battery cell 1 via the lead wire 22 and the bus bar 3. In order to securely connect the lead wire 22 to the bus bar 3, the bus bar 3 has a voltage detection terminal 23 fixed thereto. The voltage detection terminal 23 is fixed to the surface of the plating layer 34 provided on the copper plate 32 of the bus bar 3 by a method such as welding or soldering as shown in FIGS. The plated layer 34 can reliably and stably fix the metal voltage detection terminal 23. The lead wire 22 is soldered and connected to the voltage detection terminal 23.

The above battery pack is assembled in the following steps.
(1) A predetermined number of battery cells 1 are stacked in the thickness direction of the battery cell 1 with a spacer 6 interposed therebetween to form a battery stack 9. At this time, the plurality of battery cells 1 stacked on each other are stacked such that the positive and negative electrode terminals 2 at both ends of the sealing plate 12 are alternately reversed.
(2) The end plates 4 are stacked on both ends of the battery stack 9, the pair of end plates 4 are pressed from both sides, and the battery stack 9 is pressed in the stacking direction of the battery cells 1.
(3) At the lower ends of the both side surfaces of the battery stack 9, the lower corners of the pair of end plates 4 arranged on both end surfaces of the battery stack 9 are connected by the connector 5.
(4) Furthermore, the surface plate 8 is disposed at a fixed position on the upper surface of the battery stack 9 in a state where the battery stack 9 is pressed in the stacking direction of the battery cells 1.
(5) At the upper ends of both side surfaces of the battery stack 9, the upper corners of the pair of end plates 4 arranged on both end surfaces of the battery stack 9 are connected by the connector 5. In this state, the battery cells 1 in the stacked state are fixed in the stacking direction in a pressurized state via the connector 5, and both side edges of the surface plate 8 are fixed to the battery stack 9 with the connector 5.

(6) The opposite electrode terminals 2 and 52 of the battery cells 1 adjacent to each other are connected by the bus bar 3 on both sides of the battery stack 9. The bus bar 3 is disposed in the opening window 29 of the surface plate 8 and connects the positive terminals 2A and 52A and the negative terminals 2B and 52B exposed from the opening window 29. The battery cells 1 adjacent to each other are connected in series by the bus bar 3, and the battery cells 1 constituting the battery stack 9 are connected in series.
At this time, the electrode terminal 2 shown in FIGS. 8 to 10 is connected to the bus bar 3 as follows.
[1] As shown in FIGS. 8 and 10, the electrode terminals 2 of the adjacent battery cells 1 are inserted into the through holes 38 provided at both ends of the bus bar 3. At this time, the positive electrode terminal 2 </ b> A is inserted into the circular close-contact hole 38 </ b> B provided in the aluminum plate 31, and the negative electrode terminal 2 </ b> B is inserted into the long-hole-shaped gap through hole 38 </ b> A provided in the copper plate 32. In this state, there is no gap between the close contact through hole 38B and the positive electrode terminal 2A, but there is a gap between the long gap through hole 38A and the negative electrode terminal 2B.
[2] The fixing ring 7 as the welding ring 7A is placed on the bus bar 3, and the negative electrode terminal 2B inserted in the clearance through hole 38A is inserted into the center hole of the welding ring 7A. Since the outer shape of the weld ring 7A is larger than the gap through hole 38A, the gap between the gap through hole 38A and the negative electrode terminal 2B is closed.
[3] As shown in FIGS. 9 and 10, the circular contact through hole 38 </ b> B irradiates a laser beam along the circumference thereof, and laser-welds the positive electrode terminal 2 </ b> A to the bus bar 3. The long hole-shaped gap through-hole 38A irradiates a laser beam along the inner and outer peripheral edges of the fixing ring 7 which is the welding ring 7A, and the inner peripheral edge of the center hole of the welding ring 7A is applied to the negative electrode terminal 2B. The outer peripheral edge is laser welded to the bus bar 3.
Moreover, the electrode terminal 52 shown in FIG. 11 is connected to the bus bar 3 as follows.
[1] As shown in FIG. 11, the electrode terminals 52 of the adjacent battery cells 51 are inserted into the through holes 38 provided at both ends of the bus bar 3. At this time, the positive electrode terminal 52 </ b> A is inserted into the circular close-contact hole 38 </ b> B provided in the aluminum plate 31, and the negative electrode terminal 52 </ b> B is inserted into the long-hole-shaped gap through hole 38 </ b> A provided in the copper plate 32.
[2] The nut 7Ba is screwed into the tip of the positive electrode terminal 52A, and the nut 7Bb is screwed into the tip of the negative electrode terminal 52B to connect each electrode terminal 52 to the bus bar 3.

(7) The circuit board 20 is fixed at a fixed position above the surface plate 8. Furthermore, the lead wires 22 drawn out from the voltage detection circuit 21 mounted on the circuit board 20 are connected to each bus bar 3. Each lead wire 22 has a voltage detection terminal 23 connected to the tip, and the voltage detection terminal 23 is fixed to the surface of the plating layer 34 of the bus bar 3 by a method such as welding or soldering.
Here, the order of the steps (6) and (7) can be reversed.

  The above battery pack can be used as an in-vehicle power source. As a vehicle equipped with a battery pack, an electric vehicle such as a hybrid vehicle or a plug-in hybrid vehicle that runs with both an engine and a motor, or an electric vehicle that runs only with a motor can be used, and it is used as a power source for these vehicles. .

(Battery pack for hybrid vehicles)
FIG. 12 shows an example in which a battery pack is mounted on a hybrid vehicle that runs with both an engine and a motor. A vehicle HV equipped with the battery pack shown in this figure includes an engine 96 and a running motor 93 that run the vehicle HV, a battery pack 100 that supplies power to the motor 93, and a generator that charges the batteries of the battery pack 100. 94, a vehicle main body 90 on which an engine 96, a motor 93, a battery pack 100, and a generator 94 are mounted, and wheels 97 that are driven by the engine 96 or the motor 93 to run the vehicle main body 90. The battery pack 100 is connected to a motor 93 and a generator 94 via a DC / AC inverter 95. The vehicle HV travels by both the motor 93 and the engine 96 while charging / discharging the battery of the battery pack 100. The motor 93 is driven in a region where the engine efficiency is poor, for example, during acceleration or during low-speed traveling, and causes the vehicle HV to travel. The motor 93 is driven by power supplied from the battery pack 100. The generator 94 is driven by the engine 96 or is driven by regenerative braking when braking the vehicle HV, and charges the battery of the battery pack 100.

(Electric vehicle battery pack)
FIG. 13 shows an example in which a battery pack is mounted on an electric vehicle that runs only by a motor. A vehicle EV equipped with the battery pack shown in this figure has a traveling motor 93 for traveling the vehicle EV, a battery pack 100 for supplying electric power to the motor 93, and a generator 94 for charging a battery of the battery pack 100. And a vehicle body 90 on which the motor 93, the battery pack 100, and the generator 94 are mounted, and a wheel 97 that is driven by the motor 93 and causes the vehicle body 90 to travel. The battery pack 100 is connected to a motor 93 and a generator 94 via a DC / AC inverter 95. The motor 93 is driven by power supplied from the battery pack 100. The generator 94 is driven by energy when regenerative braking of the vehicle EV and charges the battery of the battery pack 100.

(Battery pack for power storage device)
Furthermore, this battery pack can be used not only as a power source for a mobile body but also as a stationary power storage facility. For example, as a power source for home and factory use, a power supply system that is charged with sunlight or midnight power and discharged when necessary, or a streetlight power supply that charges sunlight during the day and discharges at night, or during a power outage It can also be used as a backup power source for driving signals. Such an example is shown in FIG. In the battery pack 100 shown in this figure, a plurality of battery blocks 81 are connected in a unit form to constitute a battery unit 82. Each battery block 81 has a plurality of batteries connected in series and / or in parallel. Each battery block 81 is controlled by a power supply controller 84. The battery pack 100 drives the load LD after charging the battery unit 82 with the charging power source CP. For this reason, the battery pack 100 has a charge mode and a discharge mode. The load LD and the charging power source CP are connected to the battery pack 100 via the discharging switch DS and the charging switch CS, respectively. ON / OFF of the discharge switch DS and the charge switch CS is switched by the power supply controller 84 of the battery pack 100. In the charging mode, the power controller 84 switches the charging switch CS to ON and the discharging switch DS to OFF to permit charging of the battery pack 100 from the charging power source CP. Further, when the charging is completed and the battery is fully charged, or in response to a request from the load LD in a state where a capacity of a predetermined value or more is charged, the power controller 84 turns off the charging switch CS and turns on the discharging switch DS to discharge. The mode is switched and discharging from the battery pack 100 to the load LD is permitted. Further, if necessary, the charge switch CS can be turned on and the discharge switch DS can be turned on to supply power to the load LD and charge the battery pack 100 simultaneously.

  A load LD driven by the battery pack 100 is connected to the battery pack 100 via a discharge switch DS. In the discharge mode of the battery pack 100, the power supply controller 84 switches the discharge switch DS to ON, connects to the load LD, and drives the load LD with the power from the battery pack 100. As the discharge switch DS, a switching element such as an FET can be used. ON / OFF of the discharge switch DS is controlled by the power supply controller 84 of the battery pack 100. The power controller 84 also includes a communication interface for communicating with external devices. In the example of FIG. 14, the host device HT is connected in accordance with an existing communication protocol such as UART or RS-232c. Further, if necessary, a user interface for the user to operate the power supply system can be provided.

  Each battery block 81 includes a signal terminal and a power supply terminal. The signal terminals include an input / output terminal DI, an abnormal output terminal DA, and a connection terminal DO. The input / output terminal DI is a terminal for inputting / outputting a signal from the other battery block 81 or the power supply controller 84, and the connection terminal DO is a terminal for inputting / outputting a signal to / from the other battery block 81. . The abnormality output terminal DA is a terminal for outputting abnormality of the battery block 81 to the outside. Furthermore, the power supply terminal is a terminal for connecting the battery blocks 81 in series and in parallel. The battery units 82 are connected to the output line OL via the parallel connection switch 85 and are connected in parallel to each other.

  The battery pack according to the present invention can be suitably used as a battery pack for a plug-in hybrid electric vehicle, a hybrid electric vehicle, an electric vehicle or the like that can switch between the EV traveling mode and the HEV traveling mode. In addition, backup battery packs that can be mounted on computer server racks, backup battery packs for wireless base stations such as mobile phones, power storage power sources for home use and factories, power sources for street lights, etc. It can also be used as appropriate for applications such as backup power supplies for devices and traffic lights.

DESCRIPTION OF SYMBOLS 100 ... Battery pack 1 ... Battery cell 2 ... Electrode terminal 2A ... Positive electrode terminal
2B ... Negative electrode terminal 3 ... Bus bar 4 ... End plate 5 ... Connector 6 ... Spacer 7 ... Fixing ring 7A ... Welding ring
7B ... Nut
7Ba ... Nut
7Bb ... Nut 8 ... Surface plate 9 ... Battery laminate 10 ... Electrode body 11 ... Exterior can 12 ... Sealing plate 13 ... Insulating material 14 ... Current collector 15 ... Current blocking mechanism 16 ... Deformed metal plate 17 ... Connecting metal 18 ... Mounted Part 19 ... Safety valve 20 ... Circuit board 21 ... Voltage detection circuit 22 ... Lead wire 23 ... Voltage detection terminal 29 ... Opening window 30 ... Cladding material 31 ... Aluminum plate 32 ... Copper plate 34 ... Plating layer 38 ... Through hole 38A ... Gap through hole
38B ... Close contact through hole 39 ... Play gap 51 ... Battery cell 52 ... Electrode terminal 52A ... Positive electrode terminal
52B ... Negative electrode terminal 54 ... Male screw 81 ... Battery block 82 ... Battery unit 84 ... Power supply controller 85 ... Parallel connection switch 90 ... Vehicle body 93 ... Motor 94 ... Generator 95 ... DC / AC inverter 96 ... Engine 97 ... Wheel 201 ... Battery cell 202 ... electrode terminal 203 ... bus bar 204 ... through hole 204A ... through hole 206 ... welding ring 301 ... battery cell 302 ... electrode terminal 303 ... bus bar 304 ... through hole 307 ... nut EV ... vehicle HV ... vehicle LD ... load CP ... Power supply for charging DS ... Discharge switch CS ... Charge switch OL ... Output line HT ... Host equipment DI ... Input / output terminal DA ... Abnormal output terminal DO ... Connection terminal

Claims (10)

A metal plate bus bar is fixed to electrode terminals of a plurality of battery cells, and the bus bar is a battery pack formed by connecting battery cells in series and / or in parallel.
The bus bar has a plurality of through holes for inserting electrode terminals of battery cells to be connected;
The through hole is larger than the outer shape of the electrode terminal, and there is a clearance gap between the through hole and the electrode terminal, and a gap through hole into which the electrode terminal can be displaced and inserted,
A fixing ring is inserted into the electrode terminal inserted into the gap through hole, and the fixing ring electrically connects the electrode terminal to the bus bar,
Further, the bus bar is a part of the entire surface, a plating layer is provided on a surface facing the fixing ring, and the fixing ring is electrically connected to the plating layer on the surface of the bus bar. The fixing ring is a weld ring, and the weld ring is provided with the same metal plate as the plating layer or the same metal plate as the bus bar and the same plating layer as the bus bar on the surface.
The fixing ring which is a welding ring is described in claim 1, wherein the inner peripheral edge is laser welded to the electrode terminal, the outer peripheral edge is laser welded to the plating layer on the bus bar surface, and the electrode terminal is electrically connected to the bus bar. Battery pack. The fixing ring is a nut, and the nut is provided with the same plating layer as the bus bar on the surface,
The electrode terminal has a male screw fixed by screwing a nut, the nut is screwed into the male screw of the electrode terminal, and the plating layer on the surface of the nut contacts the plating layer on the surface of the bus bar. The battery pack according to claim 1, wherein the electrode terminal is electrically connected to the bus bar. The battery cell is a lithium ion battery in which the positive electrode terminal is made of aluminum and the negative electrode terminal is made of copper.
The bus bar is a metal clad material formed by joining an aluminum plate and a copper plate, and a plating layer is provided on the surface of the copper plate,
The positive electrode terminal of the battery cell is electrically connected to the aluminum plate of the bus bar, the negative electrode terminal is electrically connected to the copper plate of the bus bar, and the negative electrode terminal inserted into the through hole of the copper plate is electrically connected to the copper plate via the fixing ring. The battery pack according to any one of claims 1 to 3.   5. The battery pack according to claim 1, wherein the plating layer of the bus bar is nickel plating, and the fixing ring is a weld ring of a nickel plate.   The battery cell is a square battery, the square battery is fixed in a stacked state to form a battery stack, and the battery cell electrode terminals of the battery stack are connected in series and / or in parallel via a bus bar. The battery pack according to any one of claims 1 to 5. The fixing ring is a weld ring;
The bus bar has a close contact hole that contacts the outer peripheral surface of the electrode terminal, and a clearance through hole that has a play gap between the inner peripheral surface of the electrode terminal and allows the electrode terminal to be displaced and inserted. ,
The electrode terminal inserted into the close contact through hole is electrically connected by laser welding between the electrode terminal and the close contact through hole,
The electrode terminal formed in the gap through hole is electrically connected to the bus bar via a welding ring formed by laser welding the inner periphery to the electrode terminal and laser welding the outer periphery to the plating layer of the bus bar. Item 7. The battery pack according to any one of Items 1 to 6.   A voltage detection circuit for detecting the voltage of the battery cell is provided, a voltage detection terminal is connected to the plating layer of the bus bar, a lead wire is connected to the voltage detection terminal, and the voltage of the battery cell is connected via the lead wire. The battery pack according to claim 1, wherein the detection terminal is connected to a voltage detection circuit. An electric vehicle comprising the battery pack according to any one of claims 1 to 8,
The battery pack, a traveling motor powered by the battery pack, a vehicle body on which the battery pack and the motor are mounted, and a wheel that is driven by the motor and causes the vehicle body to travel. An electric vehicle comprising a battery pack characterized by the above. A power storage device comprising the battery pack according to any one of claims 1 to 8,
A power controller for controlling charging and discharging of the battery pack;
A power storage device, wherein the power supply controller controls the battery pack to charge the battery pack with external power and charges the battery pack.

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