Battery pack

Abstract

This battery pack is provided with: a plurality of secondary battery cells which are arranged in a posture parallel to each other in the longitudinal direction, each secondary battery cell having end-surface electrodes at both ends, and at least one of the end-surface electrodes serving as a first electrode to which a relief valve is provided; a battery holder for holding the plurality of secondary battery cells; and a conductive lead plate that connects the end surface electrodes of adjacent secondary battery cells to each other, the lead plate forming an open space between the first electrodes of adjacent secondary battery cells.

Description

Technical Field

[0001] The present disclosure relates to battery packs. Background Art

[0002] A battery pack formed by connecting multiple secondary battery cells in series or in parallel is used as a power source for portable electric devices such as portable speakers, electric cleaners, and electric tools, or as a backup power source for servers for stationary power storage purposes, a power source for home use, office use, and factory use, and is also used as a driving power source for power-assisted bicycles, electric carts, electric scooters, or hybrid vehicles, electric vehicles, and other vehicles. Such a battery pack is mostly held in an adjacent posture by a battery holder, and adjacent secondary battery cells are connected by welding with a plate-shaped lead plate (for example, see Patent Document 1).

[0003] For the secondary battery cells used in such battery packs, lithium-ion secondary batteries are generally used, but lithium-ion secondary battery cells may cause unsafe events accompanied by smoke and fire due to some abnormality. Therefore, a safety valve is provided on the end face (for example, the end face on the positive electrode side) of the electrode formed by the lithium-ion secondary battery cell, and is configured so that when the internal pressure of the outer tank of the secondary battery cell increases, the safety valve opens and releases the internal high-pressure gas to the outside. However, assuming that an unsafe event occurs in any secondary battery cell, it is believed that the high-temperature gas, flame, electrolyte and other discharges released from the safety valve of the secondary battery cell are transferred through the lead plate and moved to other adjacent secondary battery cells, which may be damaged and spread to the fire.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-033464 Summary of the invention

[0007] One of the objects of the present disclosure is to provide a battery pack in which adjacent secondary battery cells are connected by a lead plate, and even if an abnormality occurs in one secondary battery cell, damage to other adjacent secondary battery cells can be suppressed.

[0008] A battery pack involved in one embodiment of the present invention comprises: a plurality of secondary battery cells having end surface electrodes at both ends, at least one of the end surface electrodes being used as a first electrode provided with a safety valve, and arranged in a posture parallel to the length direction; a battery holder for holding the plurality of secondary battery cells; and a conductive lead plate for connecting the end surface electrodes of adjacent secondary battery cells to each other, the lead plate forming an open space between the first electrodes of adjacent secondary battery cells.

[0009] According to the battery pack involved in one aspect of the present invention, since the first electrodes of adjacent secondary battery cells are not completely blocked by lead plates and an open space is provided, even if any secondary battery cell abnormally releases high-temperature gas or other exhaust gases, it is possible to reduce the adverse effects on other adjacent secondary battery cells by releasing them to the outside through the open space. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a perspective view showing the appearance of a battery pack according to an embodiment of the present invention.

[0011] Figure 2 yes Figure 1 A vertical cross-sectional view of a battery pack taken along line II-II.

[0012] Figure 3 It is shown Figure 1 A three-dimensional diagram of the manufacturing process of a battery pack.

[0013] Figure 4 yes Figure 3 An exploded perspective view of a battery assembly of a battery pack.

[0014] Figure 5 Yes Figure 4 An exploded perspective view of a battery assembly with the lead plate removed.

[0015] Figure 6 Yes Figure 4 An exploded rear perspective view of a battery assembly with the lead plate removed.

[0016] Figure 7 Yes Figure 5 An exploded perspective view of a battery assembly after the battery holder is disassembled.

[0017] Figure 8 yes Figure 4 Front view of the battery assembly shown.

[0018] Fig. 9 yes Figure 4 Rear view of the battery assembly shown.

[0019] Fig.10 yes Figure 2 An enlarged cross-sectional view of the main parts of the battery pack.

[0020] Fig.11 This is a schematic cross-sectional view showing a state in which waste is discharged from a secondary battery cell of a conventional battery pack.

[0021] Fig.12This is a schematic cross-sectional view showing a state where waste is discharged from a secondary battery cell of the battery pack of the present invention. DETAILED DESCRIPTION

[0022] The embodiments of the present invention can also be identified by the following structures and features.

[0023] Regarding the battery pack involved in another embodiment of the present invention, it may also be that in the above embodiment, the lead plate has: a plurality of cross pieces connected to the first electrode of each secondary battery cell and extending in a second direction respectively, the second direction intersecting with a first line that connects the centers of the first electrodes of adjacent secondary battery cells in the shortest manner; and a connecting portion extending from the end edge of each cross piece connected to the adjacent secondary battery cell in parallel with the first line and connecting each cross piece, and an open space is formed by the cross piece and the connecting portion. According to the above structure, by making the lead plate detour so as not to overlap with the first line that connects the first electrodes of adjacent secondary battery cells in the shortest manner, an open space can be formed between the first electrodes of adjacent secondary battery cells while maintaining electrical connection.

[0024] Regarding a battery pack according to another aspect of the present invention, in the above aspect, the open space may be formed in a U-shape in a plan view by adjacent cross pieces and the connecting portion of the lead plate.

[0025] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, the cross piece is arranged between the first electrodes of adjacent secondary battery cells, and the lead plate further includes: a welding piece extending from each cross piece along the first line to the first electrode of the corresponding secondary battery cell. According to the above structure, the lead plate can be welded to the first electrode of the secondary battery cell using the welding piece.

[0026] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, open spaces are formed around the first electrodes of each secondary battery cell, and between the mutually adjacent first electrodes, the cross piece connected to one first electrode and the open space formed around the other first electrode are arranged on the first line. According to the above structure, it is set as a structure in which the discharge discharged from the safety valve of the first electrode of the secondary battery cell is discharged to the outside from the open space formed around the first electrode, and even if it is assumed that a part of the discharge passes between the cross piece connected to the first electrode and the battery holder along the first line, it will be discharged to the outside from the open space formed around the adjacent first electrode. Therefore, the discharge discharged from the first electrode can reliably pass through the open space, and the frame influence on the adjacent secondary battery cell can be ideally suppressed.

[0027] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, the battery holder forms an outer shape into a box shape, and the battery holder is configured with first electrodes of multiple secondary battery cells along a first side of the first surface forming the box shape, and the lead plate also has: a bending piece, which is bent from a connecting portion located on the first surface to a second surface intersecting the first side of the first surface. According to the above structure, the area of ​​the conductive path can be obtained by adding a bending piece independent of the connecting portion. In particular, since an open space is formed on the first line that connects the first electrodes of adjacent secondary battery cells to each other in the shortest possible manner, a bending piece can be added to compensate for the amount of area loss of a portion of the conductive path.

[0028] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, at the connection part where the connection part and the bent piece are connected on the first side, an area where the first electrodes of a plurality of secondary battery cells are arranged on the first surface is provided, and an opening is formed at the connection part. According to the above structure, even if the safety valve at the first electrode of the secondary battery cell is opened and high-temperature gas and other exhaust are ejected, it can be discharged through the opening to the lateral direction where there is no secondary battery cell, thereby avoiding or suppressing the situation of causing damage to other secondary battery cells.

[0029] In a battery pack according to another aspect of the present invention, in the above aspect, the lead plate may further include a connecting portion connecting the connection portion and the bent piece, the connecting portion being disposed opposite to a region between first electrodes of adjacent secondary battery cells on the first surface.

[0030] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, the battery pack has a plurality of parallel units, and the parallel units are formed by arranging secondary battery cells in parallel postures and connecting them in parallel. The plurality of parallel units are connected in series with each other to form a battery block in which a plurality of secondary battery cells held by a battery holder are connected in series and parallel, and the lead plate is set as an output lead plate connected to the output side of the battery block.

[0031] Regarding the battery pack involved in another embodiment of the present invention, it can also be that in the above embodiment, the battery pack has a plurality of parallel units, and the parallel units are arranged in a parallel posture with secondary battery cells and connected in parallel. The plurality of parallel units are connected in series with each other to form a battery block in which a plurality of secondary battery cells held by a battery holder are connected in series and parallel. The lead plate is an intermediate lead plate that connects the parallel units in series, and the intermediate lead plate comprises: a plate-like laminated portion, connected to a second electrode in a direction parallel to a first line, the second electrode being an end face electrode on the opposite side of the first electrode of an adjacent secondary battery cell, the plate-like laminated portion is also used as a connecting portion, and has a plurality of cross pieces extending from the plate-like laminated portion respectively in the second direction, and the cross pieces are connected to the first electrodes of corresponding secondary battery cells.

[0032] A battery pack according to another aspect of the present invention may include, in the above aspect, an insulating plate covering a surface of the lead plate to insulate the lead plate, and the insulating plate may include a discharge hole for passing discharge from the secondary battery cells at a position facing the open space.

[0033] In a battery pack according to another aspect of the present invention, in the above aspect, the discharge hole may be in a slit shape.

[0034] Hereinafter, the embodiments of the present invention will be described based on the accompanying drawings. However, the embodiments shown below are examples for concretizing the technical ideas of the present invention, and the present invention is not limited to the following. In addition, this specification does not limit the components shown in the claims to the components of the embodiments. In particular, the size, material, shape, relative configuration, etc. of the structural parts recorded in the embodiments are not intended to limit the scope of the present invention to this, as long as there is no specific record, but are just simple illustrative examples. In addition, for the sake of clarity, the size, positional relationship, etc. of the components shown in the drawings are sometimes exaggerated. Further, in the following description, for the same name, symbol, the same or homogeneous components are represented, and detailed description is appropriately omitted. Further, the elements constituting the present invention can be a method in which the same components constitute multiple elements so that one component can be used as multiple elements. On the contrary, it can also be realized by multiple components sharing the function of one component.

[0035] The battery pack of the present invention can be used as a power source for electrical equipment such as speakers, electric cleaners, and electric tools, or as a backup power source for servers, a power supply device for home use, office use, and factory use in a stationary power storage purpose, and can also be used as a driving power source for power-assisted bicycles, electric scooters, electric carts, or hybrid vehicles, electric vehicles, and other vehicles. Below, as one embodiment of the present invention, a battery pack used as a power source for a wireless speaker is described.

[0036] [Implementation Method 1]

[0037] The battery pack 100 according to the first embodiment of the present invention is shown in FIG. Figures 1 to 10 . Figure 1 The figure shows the appearance of the battery pack. Figure 2 Shows Figure 1 A vertical cross-sectional view of the battery pack along line II-II, Figure 3 Shown Figure 1 A three-dimensional diagram of the manufacturing process of a battery pack. Figure 4 Shows Figure 3 An exploded perspective view of a battery assembly of a battery pack, Figure 5 as well as Figure 6 Shows the Figure 4 The exploded perspective view and the exploded rear perspective view of the battery assembly after the lead plate is removed, Figure 7 Shows the Figure 5 An exploded perspective view of a battery assembly after the battery holder is disassembled, Figure 8 as well as Fig. 9 Shows Figure 4 The front view and rear view of the battery assembly shown, Fig.10 Shows Figure 2 The battery pack 100 shown in these figures comprises: a plurality of secondary battery cells 1, at least one of the end surface electrodes 11 being a first electrode 11A provided with a safety valve, and arranged in a posture parallel to the longitudinal direction; a battery holder 2 for holding the plurality of secondary battery cells 1; and a conductive lead plate 3 for connecting the end surface electrodes 11 of adjacent secondary battery cells 1 to each other.

[0038] (Battery assembly 10)

[0039] Figures 1 to 10 The battery pack 100 shown has lead plates 3 fixed to both end surfaces of a battery holder 2 that accommodates a plurality of secondary battery cells 1, and a circuit substrate 4 is arranged on the upper portion of the battery holder 2 to form a battery assembly 10. On the outer peripheral surface of the battery assembly 10, the surface of the lead plate 3 is covered by an insulating plate 5, the upper surface of the battery assembly 10 is covered by an insulating member 6, and the battery assembly 10 whose surface is insulated is covered by an outer sheet 7.

[0040] (Secondary battery cell 1)

[0041] Each secondary battery cell 1 is a cylindrical secondary battery cell whose outer can is cylindrical. As an example, the secondary battery cell 1 can use a component that contains an electrode body in a metal outer can, fills the electrolyte, and hermetically seals the opening of the outer can with a sealing plate. The cylindrical secondary battery cell is provided with end surface electrodes 11 at both ends in the length direction. The secondary battery cell 1 uses the bottom surface of the outer can as the two end surfaces and the electrodes provided in the center of the sealing plate as positive and negative electrodes. In addition, the secondary battery cell 1 uses at least one of the end surface electrodes 11 at both ends as a first electrode 11A provided with a safety valve (not shown). The secondary battery cell 1 in the figure is formed by a convex electrode arranged in the center of the sealing plate to form a first electrode 11A provided with a safety valve, and another end surface electrode 11 is formed by the bottom surface electrode of the outer can as a second electrode 11B. The safety valve opening is a component for releasing the internal gas when the internal pressure of the outer can rises. Therefore, all secondary batteries that discharge the exhaust of the gas lamp when the internal pressure rises and the safety valve opens can be used for the secondary battery cell 1. In addition, the safety valve is generally set on the positive electrode side, but the present invention does not limit the location of the safety valve to the positive electrode side, and can also be set at other locations, such as the negative electrode side.

[0042] Such a secondary battery cell 1 can suitably utilize a non-aqueous electrolyte secondary battery with high energy efficiency, such as a lithium-ion secondary battery. However, the battery pack of the present invention does not limit the secondary battery cell to a lithium-ion secondary battery, nor does it limit the secondary battery cell to a cylindrical battery. For the secondary battery cell, all rechargeable batteries, such as nickel-hydrogen batteries, nickel-cadmium batteries, etc., can also be used.

[0043] (Battery holder 2)

[0044] The battery holder 2 holds a plurality of secondary battery cells 1 . Figure 2 The battery holder 2 holds the plurality of secondary battery cells 1 in parallel in the longitudinal direction and with the end electrodes 11 at both ends arranged on the same plane. The battery holder 2 has a box-like outer shape and arranges the plurality of secondary battery cells 1 in multiple stages and rows. Figure 7The battery holder 2 is formed of plastic into a shape having a retaining tube 22 that arranges a plurality of secondary battery cells 1 in a fixed position. The battery holder 2 is a shape in which eight retaining tubes 22 are connected in a parallel posture into four levels and two columns, so that the inner side of the retaining tube 22 is almost equal to the outer shape of the secondary battery cell 1, to serve as a storage space 21. The battery holder 2 in the figure holds eight secondary battery cells 1 in four levels and two columns, so that they are arranged in a posture along the top, bottom, left and right in the figure. The battery holder 2 in the figure arranges eight secondary battery cells 1 in a matrix shape, so that they are in a left-right symmetrical posture when viewed from the front. This structure has the advantage of being able to maintain the battery holder 2 with multiple levels of secondary battery cells 1 in a stable upright posture. The number and arrangement of the secondary battery cells 1 are not limited to this structure, and can also be set to a structure with less than 7 or more than 9 secondary battery cells 1. In addition, it is not limited to four levels and two columns, and various changes can be made to the number of levels and columns. In addition, in addition to being arranged in a matrix shape, it can also be arranged in a staggered shape in an alternating manner in each level. The battery holder 2 is made of a material having excellent insulation and heat resistance, for example, a resin such as polycarbonate or ABS.

[0045] Figure 7 The battery holder 2 is divided into a first holder 2X and a second holder 2Y in the longitudinal direction of the secondary battery cell 1. The battery holder 2 can smoothly insert the elongated secondary battery cell 1.

[0046] The first holder 2X and the second holder 2Y are independently formed by molding plastic and connected to each other by inserting the secondary battery cell 1. The first holder 2X and the second holder 2Y are provided with a cylindrical accommodation space 21 to insert and arrange the cylindrical secondary battery cell 1 at a fixed position.

[0047] The internal shape of the storage space 21 is almost the same as the external shape of the secondary battery cell 1. To be precise, it is slightly larger so that the secondary battery cell 1 can be smoothly inserted and arranged in a fixed position. The first retainer 2X and the second retainer 2Y of this structure are connected to each other at a fixed position via the secondary battery cell 1 when both ends of the cylindrical secondary battery cell 1 are inserted. The first retainer 2X and the second retainer 2Y can be more accurately connected by setting the opposing surfaces as a fitting structure, and are also connected at a fixed position via the non-melting plate 13 described later.

[0048] Figure 2 and Figure 7The battery assembly 10 shown has a non-melting plate 13 such as a mica plate arranged inside a partition wall 23 arranged between adjacent secondary battery cells 1. The battery holder 2 in the figure arranges the secondary battery cells 1 in 4 levels and 2 rows, so a cross-shaped partition wall 23 is arranged along the top and bottom between the 8 secondary battery cells 1 arranged vertically and horizontally. The partition wall 23 is provided with an insertion gap for inserting the internal non-melting plate 13. The partition wall 23 is inserted into the non-melting plate 13 such as a mica plate in the insertion gap. The battery assembly 10 can prevent the adjacent secondary battery cells 1 from inducing thermal runaway when any one of the secondary battery cells 1 is abnormally heated due to thermal runaway.

[0049] Furthermore, the battery holder 2 is provided with a connection window 24 for exposing the end surface electrode 11 to connect the lead plate 3 at a position opposite to the end surface electrode 11 of the secondary battery cell 1. The connection window 24 for guiding the first electrode 11A as the protruding electrode is set to a size larger than the outer shape of the protruding electrode and capable of inserting the protruding electrode inside. The connection window 24 can arrange the protruding electrode inside and weld it to the lead plate 3, so that the step with the first electrode 11A exposed from the connection window 24 can be reduced, and the lead plate 3 can be welded to the first electrode 11A. The connection window 24 arranged at a position opposite to the second electrode 11B as the bottom surface of the outer can is opened to a size that can guide the welding piece 33 of the lead plate 3 to the second electrode 11B.

[0050] Furthermore, the battery holder 2 is provided with a receiving area 25 at the upper portion for receiving the circuit substrate 4 . Figure 6 The battery holder 2 shown has front, rear, left, and right peripheral walls protruding from the upper surface, and has recessed portions formed inside the four peripheral walls to serve as a storage area 25 for the circuit board 4 . Figure 2 The circuit board 4 is arranged in a gap between the battery holder 2 and the bottom surface of the storage area 25 . Figure 6 The circuit board 4 is arranged at a fixed position by setting the outer periphery to fit the inner periphery of the storage area 25. However, the battery holder may be directly fixed to the circuit board installation area by screw fastening or the like, or a substrate holder for holding the circuit board may be separately provided.

[0051] (Lead plate 3)

[0052] The lead plate 3 electrically connects the secondary battery cells 1 held in the battery holder 2. The lead plate 3 is manufactured by stamping a metal plate having excellent conductivity, and is welded and fixed to the end surface electrode 11 provided on the end surface of the secondary battery cell 1 of the battery holder 2. The battery assembly 10 shown in the figure connects eight secondary battery cells 1 in series and in parallel via the lead plate 3. Figure 7The battery assembly 10 is configured by connecting four secondary battery cells 1 arranged in two rows and four levels in the figure in parallel to each other to form a parallel unit 1X, and connecting the left and right parallel units 1X to each other in series to form a battery block 1Y in which eight secondary battery cells 1 are connected in four parallel connections and two in series. Figure 6 as well as Fig. 9 As shown, on the third surface 2C of the box-shaped battery holder 2, the battery assembly 10 connects two sets of parallel units 1X in series via the intermediate lead plate 3B, and as shown in FIG. Figure 5 as well as Figure 7 As shown, in this battery assembly 10 , the output sides of the parallel cells 1X connected in series are connected to the output lead plate 3A on the first surface 2A of the battery holder 2 .

[0053] The output lead plate 3A includes a first output lead plate 3Aa for connecting the first electrodes 11A of the plurality of secondary battery cells 1 constituting the parallel unit 1X, and a second output lead plate 3Ab for connecting the second electrodes 11B. Fig. 9 As shown in the figure, the intermediate lead plate 3B connects the adjacent second electrodes 11B of one parallel unit 1X among the parallel units 1X connected in series to each other on the left side, and connects the adjacent first electrodes 11A of the other parallel unit 1X to each other on the right side. As shown in these figures, the first output lead plate 3Aa and the intermediate lead plate 3B connecting the adjacent first electrodes 11A to each other form an open space 30 for discharging the exhaust such as gas discharged from the safety valve of the first electrode 11A to the outside between the first electrodes 11A of the adjacent secondary battery cells 1.

[0054] like Figure 8 as well as Fig. 9 As shown, the first output lead plate 3Aa and the intermediate lead plate 3B include a plurality of cross pieces 31 connected to the first electrodes 11A of the secondary battery cells 1, and a connection portion 32 connecting the cross pieces 31 connected to the secondary battery cells 1. The plurality of cross pieces 31 extend in a second direction, respectively, and the second direction intersects with a first line L1 that connects the centers of the first electrodes 11A of the adjacent secondary battery cells 1 in the shortest direction. The connection portion 32 extends from the end edge of each cross piece 31 connected to the adjacent secondary battery cells 1 in parallel with the first line L1, and connects the cross pieces 31. The first output lead plate 3Aa forms an open space 30 around the first electrode 11A using the cross pieces 31 and the connection portion 32.

[0055] Furthermore, the first output lead plate 3Aa and the intermediate lead plate 3B are provided with welding pieces 33, and the welding pieces 33 extend from each cross piece 31 along the first line L1 toward the first electrode 11A of the corresponding secondary battery cell 1. Each cross piece 31 shown in the figure extends in a direction parallel to the first line L1 in a plan view, but the cross piece 31 can also be arranged in a posture slightly inclined relative to the first line L1. Figure 5 As shown, these welding pieces 33 are extended with steps relative to the cross piece 31. Thus, even if there is a height difference between the height of the surface on which the lead plate 3 is arranged fixed to the battery holder 2 and the height of the surface on which the first electrode 11A is arranged, the step of the welding piece 33 can be absorbed, so that the welding piece 33 is in contact with the surface of the first electrode 11A in a surface contact state, thereby improving the reliability of welding. Furthermore, each welding piece 33 is formed with a slit 33a, and the reliability of welding is improved by pressing the welding tool across the slit 33a. The welding piece 33 in the figure divides the welding part into a pair of pieces, and a slit 33a is provided between them, but the welding piece can also be opened with a long and narrow hole as a slit.

[0056] Figure 5 as well as Figure 8 The first output lead plate 3Aa shown connects the first electrodes 11A of a plurality of secondary battery cells 1 arranged along a first side 2a of a first surface 2A of a battery holder 2 formed into a box shape. The first output lead plate 3Aa is provided at the side edge of the first surface 2A of the battery holder 2, and has a strip-shaped connecting portion 32 extending along the first side 2a, which is the boundary edge with the second surface 2B, in parallel with the first line L1. Furthermore, a cross piece 31 extending from the strip-shaped connecting portion 32 in a second direction (approximately vertical in the figure) is provided, and an open space 30 having a "U" shape when viewed from above is formed by adjacent cross pieces 31 and connecting portions 32. Figure 8 In the figure, each cross piece 31 connected to the first electrode 11A of the secondary battery cell 1 except the secondary battery cell 1 located at the bottom is arranged between the first electrodes 11A of adjacent secondary battery cells 1, and the cross piece 31 connected to the first electrode 11A of the secondary battery cell located at the bottom is arranged between the first electrode 11A and the lower end edge of the battery holder 2.

[0057] Further, Figure 5 The first output lead plate 3Aa shown in the figure has a bent piece 34, which is bent from the connection portion 32 located on the first surface 2A to the second surface 2B intersecting the first side 2a of the first surface 2A. The first output lead plate 3Aa is provided with the bent piece 34 independently of the connection portion 32, so that the area of ​​the conduction path lost by providing the open space 30 on the first line L1 can be obtained. Furthermore, Figure 5The first output lead plate 3Aa shown has an opening 35 formed at the connection portion where the connection portion 32 and the bent piece 34 are connected on the first side 2a, with respect to the region where the first electrodes 11A of the plurality of secondary battery cells 1 are provided on the first surface 2A. Thus, even if the exhaust such as gas discharged from the safety valve of the first electrode 11A enters between the connection portion 32 and the battery holder 2 and moves, it can be discharged to the outside through the opening 35 provided along the first side 2a, so that the exhaust discharged from the safety valve can be suppressed from moving along the connection portion 32 and the bent piece 34, thereby reducing the adverse effects caused by the exhaust. Furthermore, the first output lead plate 3Aa has a connecting portion 36 connecting the connection portion 32 and the bent piece 34, and the connecting portion 36 is provided opposite to the region between the first electrodes 11A of the adjacent secondary battery cells 1 on the first surface 2A. The first output lead plate 3Aa has a connection portion 32 and a bent piece 34 connected by a connection portion 36 at two locations between the first electrodes 11A, and an opening portion 35 is opened between these connection portions 36. In this structure, the connection portion 36 connecting the connection portion 32 and the bent piece 34 can prevent the side edge portion facing the first electrode 11A from being blocked, and the discharge discharged from the safety valve can be efficiently discharged to the outside.

[0058] in addition, Fig. 9 The intermediate lead plate 3B shown in the figure has a plate-shaped laminated portion 38, which is connected to the second electrode 11B of the upper and lower adjacent secondary battery cells 1 on the left side of the third surface 2C of the battery holder 2, and the plate-shaped laminated portion 38 also serves as a connecting portion 32 extending parallel to the first line L1, and a cross piece 31 extending from the connecting portion 32 in the second direction (approximately vertical direction in the figure) is provided. The intermediate lead plate 3B connects each cross piece 31 to the first electrode 11A of the upper and lower adjacent secondary battery cells 1 on the right side of the third surface 2C of the battery holder 2, and connects the upper and lower adjacent secondary battery cells 1 in parallel to each other through the plate-shaped laminated portion 38 as the connecting portion 32, and connects the left and right adjacent secondary battery cells 1 to each other in series. The intermediate lead plate 3B shown in the figure has the boundary portion of the cross piece 31 and the connecting portion 32 bent into an arc shape, and forms an open space 30 that is approximately circular in a plan view by the adjacent cross pieces 31 and the connecting portion 32.

[0059] Here, one of the focuses of the present invention is described. In the lead plate 3 that connects the adjacent first electrodes 11A to each other, it is necessary to prevent the gas or other exhaust gas discharged from the safety valve of any secondary battery cell 1 from being transmitted through the lead plate 3 and moving to the first electrode 11A of other secondary battery cells 1, thereby causing adverse effects. Fig.11As shown in the schematic cross-sectional view of FIG. 1 , in a conventional battery pack 90 in which a plurality of secondary battery cells 91 are held by a resin battery holder 92, the battery holder 92 is divided into two, and the secondary battery cells 91 are inserted into the cylinders formed in each of the divided holders, so that the secondary battery cells 91 are held from the left and right. In such a battery pack 90, any one of the secondary battery cells 91 (in Fig.11 In the case of an unsafe event in a secondary battery cell (the upper secondary battery cell), such as Fig.11 As shown by the arrow, it is considered that high-temperature gas, flame, electrolyte and other discharges released from the safety valve provided in the first electrode 91A of the secondary battery cell 91 are transmitted through the lead plate 93 and move to other adjacent secondary battery cells 91, which may be damaged and burn.

[0060] In contrast, in the battery pack 100 according to the present embodiment, Fig.12 As shown in the figure, as described above, by providing an open space 30 between adjacent first electrodes 11A in at least the lead plate 3 facing the first electrode 11A provided with the safety valve, the discharge from the safety valve can be made Fig.12 The electric current flows as indicated by the arrows, thereby greatly reducing damage to other secondary battery cells 1.

[0061] The open space 30 is formed over a region that is the surrounding region of the first electrode 11A and that is opposed to two-thirds or more of the entire circumference of the first electrode 11A. Figures 8 to 10 As shown, the open space 30 is a circular U-shaped open space 30 in a plan view, and the interval W between adjacent cross pieces 31 is wider than the radius R of the secondary battery cell 1, for example, 1.2 to 1.5 times the radius R. In this way, by setting the interval W between adjacent cross pieces 31 to be wider than the radius R of the secondary battery cell 1, for example, 1.5 times the radius R, the open space 30 is widened, so that the exhaust gas discharged from the safety valve can be prevented from being transferred through the lead plate 3 and moving to the first electrode 11A of the adjacent secondary battery, and can be efficiently discharged to the outside.

[0062] Figure 8 and Fig. 9 The lead plate 3 shown in the figure has an open space 30 formed in an area around each first electrode 11A and facing approximately 3 / 4 of the entire circumference of the first electrode 11A, and a connection portion between a welding piece 33 and a cross piece 31 is provided in the remaining area. Figure 8 as well as Fig. 9In the state where the first electrode 11A of the secondary battery cell 1 shown by A in the figure is discharging exhaust, the structure in which the open space 30 is provided over a wide area around the first electrode 11A prevents the exhaust from moving in the direction of the cross piece 31 as shown by the arrow c. This is because since the welding piece 33 is welded to the first electrode 11A, the cross piece 31 connected with the welding piece 33 is stacked in a state close to the surface of the battery holder 2, so that the exhaust is difficult to flow into the narrow gap between the battery holder 2 and the cross piece 31, and preferentially flows into the wide open space 30. Therefore, the exhaust such as gas discharged from the safety valve of the first electrode 11A is guided to the open space 30 formed around the first electrode 11A as shown by the arrows a, b, and d, and discharged to the outside. In addition, the lead plate 3 is arranged on the first line L1 between the mutually adjacent first electrodes 11A, and the cross piece 31 connected to one first electrode 11A and the open space 30 formed around the other first electrode 11A. Therefore, even if it is assumed that a part of the exhaust moves in the direction of the cross piece 31 as shown by the arrow c, the exhaust that has passed through the gap between the cross piece 31 and the battery holder 2 is discharged to the outside from the open space 30 formed between the first electrode 11A of the adjacent secondary battery cell 1 and the cross piece 31, so that the adverse effect on the first electrode 11A of the adjacent secondary battery cell 1 can be suppressed to a minimum. The lead plate 3 described above arranges the open space 30 in all directions centered on the first electrode 11A by forming the open space 30 around the first electrode 11A and the open space 30 formed on the extension line of the cross piece 31 connected to the first electrode 11A, so that the exhaust discharged from the safety valve of the first electrode 11A can be reliably discharged to the outside. In addition, in Figure 8 In the first output lead plate 3Aa shown, even if the discharge moving in the direction indicated by the arrow d in the figure enters between the connecting portion 32 and the surface of the battery holder 2, the discharge can be quickly discharged to the outside through the opening portion 35 opened along the first side 2a of the box-shaped battery holder 2.

[0063] Furthermore, in the second output lead plate 3Ab and the intermediate lead plate 3B, the lead plate 3 is also provided with welding pieces 33 connected to the second electrode 11B in the plate-shaped laminated portion 38 that connects the second electrode 11B of the adjacent secondary battery cells 1. These welding pieces 33 are connected to the plate-shaped laminated portion 38 via the fusible portion 41 extending in an elongated shape, and are provided so that the fusible portion 41 is melted when an overcurrent flows, thereby reliably cutting off the secondary battery cell 1 from the lead plate 3. The welding piece 33 is also extended with a step relative to the plate-shaped laminated portion 38, and even when there is a height difference between the surface of the battery holder 2 and the surface of the second electrode 11B, the welding piece 33 can be in contact with the surface of the second electrode 11B in a surface contact state, thereby improving the reliability of welding. Furthermore, each welding piece 33 is formed with a slit 33a similar to the above.

[0064] Furthermore, the lead plate 3 is provided with a connection terminal portion 39 protruding upward for connection with the circuit substrate 4. The connection terminal portion 39 led out from the output lead plate 3A is connected to the circuit substrate 4, and the output of the battery block 1Y is supplied to the circuit substrate 4. The connection terminal portion 39 led out from the intermediate lead plate 3B is connected to the circuit substrate 4, and the intermediate voltage of the battery block 1Y is supplied to the circuit substrate 4.

[0065] The lead plate 3 described above can be arranged at a fixed position of the battery holder 2 by means of the fitting structure. Figure 8 as well as Fig. 9 The battery holder 2 shown is formed integrally with a plurality of positioning protrusions 27 protruding from the surface on the first surface 2A and the third surface 2C. The lead plate 3 is provided with a plurality of positioning holes 37 for inserting the positioning protrusions 27. The lead plate 3 is arranged at a fixed position of the battery holder 2 in a state where the positioning holes 37 are guided to the positioning protrusions 27, and the welding piece 33 is welded to the end surface electrode 11 of the secondary battery cell 1 and fixed at the fixed position.

[0066] (Circuit board 4)

[0067] The circuit board 4 is mounted with electronic circuits such as a voltage detection circuit for detecting the total potential and the intermediate potential of the battery block 1Y that connects the secondary battery cells 1 in series and in parallel, a control circuit for controlling charging and discharging, and a protection circuit. The circuit board 4 is formed in a rectangular shape and is arranged in a storage area 25 provided on the upper part of the battery holder 2.

[0068] (Insulation board 5)

[0069] The insulating plate 5 is laminated on the surface of the lead plate 3 fixed in the battery holder 2, and covers the lead plate 3 for insulation. The insulating plate 5 is made of resin or paper, and is preferably an insulating plate that is cheap and easy to handle, and has excellent heat resistance and flame retardancy with respect to the heat of exhaust such as gas discharged from the secondary battery cell 1. As such an insulating plate, for example, aramid paper (Nomex [registered trademark] manufactured by Dupont) can be used. Figure 4 The insulating plate 5 shown comprises: a first insulating plate 5A, which is arranged on the first surface 2A of the battery holder 2 having a box-shaped outer shape and covers the output lead plate 3A; a second insulating plate 5B, which is arranged on the third surface 2C of the battery holder 2 and covers the intermediate lead plate 3B; a third insulating plate 5C, which is arranged on the second surface 2B of the battery holder 2 and covers the bent piece 34 and the connecting terminal portion 39 of the first output lead plate 3Aa; and a fourth insulating plate 5D, which is arranged on the fourth surface 2D of the battery holder 2 and covers the connecting terminal portion 39 of the second output lead plate 3Ab.

[0070] The third insulating plate 5C includes a bent piece 51 on one side of the main body portion that covers the bent piece 34 and the connection terminal portion 39 of the first output lead plate 3Aa arranged on the second surface 2B of the battery holder 2, and the bent piece 51 is arranged on the surface of the connection portion 32 of the first output lead plate 3Aa arranged on the first surface 2A of the battery holder 2. The fourth insulating plate 5D includes a bent piece 51 on one side of the main body portion that covers the connection terminal portion 39 of the second output lead plate 3Ab arranged on the fourth surface 2D of the battery holder 2, and the bent piece 51 is arranged on the surface of the plate-like laminated portion 38 of the second output lead plate 3Ab arranged on the first surface 2A of the battery holder 2. The first insulating plate 5A includes a main body portion that covers the entire first surface 2A of the battery holder 2 on which the third insulating plate 5C and the fourth insulating plate 5D are arranged, and bent pieces 51 connected to both sides of the main body portion, as shown in FIG. Figure 3 As shown, these bent pieces 51 are stacked and arranged on the surfaces of the second insulating plate 5B arranged on the second surface 2B of the battery holder 2 and the fourth insulating plate 5D arranged on the fourth surface 2D. The second insulating plate 5B includes a main body covering the entire third surface 2C of the battery holder 2 and bent pieces 51 connected to both sides of the main body, and these bent pieces 51 are arranged on the surfaces of the second surface 2B and the fourth surface 2D of the battery holder 2.

[0071] The first insulating plate 5A and the second insulating plate 5B are provided with a plurality of discharge holes 53 at positions opposite to the open space 30 provided in the lead plate 3, so that the discharge discharged from the safety valve of the first electrode 11A can be quickly discharged from the open space 30 through the discharge holes 53 of the insulating plate 5 to the outside. Figure 4The first insulating plate 5A and the second insulating plate 5B shown are provided with two rows of discharge holes 53 in the region opposite to the four open spaces 30 formed in the first output lead plate 3Aa and the intermediate lead plate 3B, that is, at four locations in the up-down direction. Each discharge hole 53 is opened as a slit hole having a total length substantially equal to the up-down width W of the open space 30, so that the discharge material discharged into the open space 30 can pass through quickly and be discharged to the outside. The first insulating plate 5A and the second insulating plate 5B are arranged so that the discharge holes 53 in four levels up and down and in two rows on the left and right are located on both sides of the first electrodes 11A arranged up and down, and are in the shape of slits parallel to the first line L1 connecting the centers of the first electrodes 11A. In this way, by providing a plurality of discharge holes 53 at positions opposite to the open spaces 30 provided in the lead plate 3, as shown in FIG. Fig.10 As shown by the arrow, the exhaust such as gas discharged from the safety valve of the first electrode 11A can be quickly guided from the open space 30 to the exhaust hole 53 and discharged to the outside. However, the shape, number, and arrangement of the exhaust holes 53 provided in the insulating plate 5 are not limited to the above examples, and various changes can be made so that the exhaust flowing into the open space 30 can be quickly discharged to the outside. In addition, each exhaust hole 53 is opened in a slit shape so as not to damage the insulation function of the first insulating plate 5A and the second insulating plate 5B.

[0072] Furthermore, the third insulating plate 5C and the first insulating plate 5A covering the first output lead plate 3Aa are provided with an opening 52 at a position opposite to the opening 35 provided in the first output lead plate 3Aa, which is a boundary portion between the main body and the bent piece 51. Thus, the discharge discharged from the safety valve of the first electrode 11A and passing through the opening 35 of the first output lead plate 3Aa can be quickly discharged to the outside through the opening 52 of the insulating plate 5.

[0073] (Exterior sheet 7)

[0074] like Figure 1 As shown, the battery assembly 10 in which the insulating plate 5 is arranged on the surface of the lead plate 3 and the surface of the circuit board 4 is covered with the insulating member 6 is covered with the outer cover sheet 7. Figure 3 As shown, the outer sheet 7 is a heat-shrinkable bag or tube, and is heat-shrunk in a state where the battery assembly 10 is contained inside, thereby covering. For such an outer sheet 7, it is preferable to use a resin such as PET that has excellent insulation and stability. In particular, a shrink tube made of PET resin is relatively cheap as a heat-shrink tube, so it is preferred.

[0075] (Pinout 18, Connector 19)

[0076] Further, Figures 1 to 7The battery pack 100 shown has a plurality of lead wires 18 connected to the circuit board 4 and led out from the battery assembly 10 to the outside. The lead wires 18 are composed of positive and negative power lines and signal lines, and are directly connected to the connector of the device in which the battery pack 100 is installed. The plurality of lead wires 18 are connected to the circuit board 4 at one end and are connected to the connector 19 at the other end.

[0077] The above battery pack 100 is built into the device body of an electrical device such as a speaker and used as a power source. The battery pack 100 supplies power to the main device via an output wire 18 led out to the outside, or supplies power from the main device to charge the built-in secondary battery cell 1. The output wire 18 led out from the battery pack 100 is connected to the connector on the main body side via an output connector 19 connected to the front end, so that power is supplied.

[0078] Industrial Applicability

[0079] The battery pack according to the present invention can be suitably used as a power source for electric devices such as wireless speakers, electric cleaners, and electric tools, and can also be suitably used in applications such as power supply devices for mobile objects such as power-assisted bicycles and electric carts.

[0080] -Explanation of symbols-

[0081] 100…Battery pack

[0082] 1…Secondary battery cell

[0083] 1X...Parallel Unit

[0084] 1Y...Battery Block

[0085] 2…Battery holder

[0086] 2X…First retainer

[0087] 2Y…Second retainer

[0088] 2A…Side 1

[0089] 2B…side 2

[0090] 2C…side 3

[0091] 2D…Fourth side

[0092] 2a…side 1

[0093] 3…Lead plate

[0094] 3A...Output lead plate

[0095] 3Aa…First output lead plate

[0096] 3Ab…Second output lead plate

[0097] 3B…Middle lead plate

[0098] 4…Circuit board

[0099] 5…Insulation board

[0100] 5A…First insulating plate

[0101] 5B…Second insulating plate

[0102] 5C…Third insulation board

[0103] 5D…Fourth insulation board

[0104] 6…Insulating components

[0105] 7…Exterior sheet

[0106] 10…Battery assembly

[0107] 11…End electrode

[0108] 11A…First electrode

[0109] 11B…Second electrode

[0110] 13…Non-melting plate

[0111] 18…Pinout

[0112] 19…Connector

[0113] 21…Accommodation space

[0114] 22…Retaining tube

[0115] 23…Partition wall

[0116] 24…Connection window

[0117] 25…Accommodation area

[0118] 27…Positioning convex part

[0119] 30…Open Space

[0120] 31…Cross-piece

[0121] 32…Connection

[0122] 33…Welding piece

[0123] 33a…Slit

[0124] 34…Bending sheet

[0125] 35…Opening

[0126] 36…Connection

[0127] 37…Positioning hole

[0128] 38…Plate-shaped laminated portion

[0129] 39…Connection terminal

[0130] 41…Fuse

[0131] 51…Bending sheet

[0132] 52…Opening

[0133] 53…Discharge hole

[0134] 90…Battery pack

[0135] 91…Secondary battery cell

[0136] 91A…First electrode

[0137] 92…Battery holder

[0138] 93…Lead plate

[0139] L1…first line.

Claims

1. A battery pack comprising: A plurality of secondary battery cells are provided with end surface electrodes at both ends, at least one of the end surface electrodes is used as a first electrode provided with a safety valve, and are arranged in a posture parallel to the longitudinal direction of each other; a battery holder that holds the plurality of secondary battery cells; and A conductive lead plate connects the end surface electrodes of adjacent secondary battery cells to each other. The lead plate forms an open space between the first electrodes of the adjacent secondary battery cells.

2. The battery pack according to claim 1, wherein: The lead plate has: A plurality of cross pieces connected to the first electrodes of the respective secondary battery cells and extending in a second direction respectively, the second direction intersecting a first line that shortest connects the centers of the first electrodes of the adjacent secondary battery cells; and The connecting portion extends from the end edge of each cross piece connected to the adjacent secondary battery cell in parallel with the first line and connects the cross pieces. The open space is formed by the cross pieces and the connecting parts.

3. The battery pack according to claim 2, wherein: The open space is formed in a U-shape in a plan view by the adjacent cross pieces and the connection portion of the lead plate.

4. The battery pack according to claim 2, wherein: The cross piece is arranged between the first electrodes of the adjacent secondary battery cells. The lead plate further includes a welding piece extending from each cross piece along the first line toward the first electrode of the corresponding secondary battery cell.

5. The battery pack according to claim 2, wherein: The open space is formed around the first electrode of each secondary battery cell. Between the first electrodes adjacent to each other, the cross piece connected to one first electrode and the open space formed around the other first electrode are arranged on the first line.

6. The battery pack according to any one of claims 2 to 5, wherein: The battery holder is formed into a box shape, and The battery holder arranges the first electrodes of the plurality of secondary battery cells along a first side of a first surface forming a box shape, The lead plate further includes a bent piece bent from the connection portion located on the first surface toward a second surface intersecting the first side of the first surface.

7. The battery pack according to claim 6, wherein: At a connection portion on the first side where the connection portion and the bent piece are connected, an opening is formed in a region where the first electrodes of the plurality of secondary battery cells are provided on the first surface.

8. The battery pack according to claim 7, wherein: The lead plate further comprises: a connecting portion connecting the connecting portion and the bent piece, The connecting portion is provided to face a region between the first electrodes of the adjacent secondary battery cells on the first surface.

9. The battery pack according to any one of claims 1 to 5, wherein: The battery pack includes a plurality of parallel units, wherein the secondary battery cells are arranged in parallel and connected in parallel. The plurality of parallel units are connected in series to each other to form a battery block in which the plurality of secondary battery cells held by the battery holder are connected in series and in parallel. The lead plate is an output lead plate connected to the output side of the battery block.

10. The battery pack according to any one of claims 2 to 5, wherein: The battery pack includes a plurality of parallel units, wherein the secondary battery cells are arranged in parallel and connected in parallel. The plurality of parallel units are connected in series to each other to form a battery block in which the plurality of secondary battery cells held by the battery holder are connected in series and in parallel. The lead plate is an intermediate lead plate that connects the parallel units in series, The intermediate lead plate includes a plate-shaped laminated portion that connects a second electrode in a direction parallel to the first line, the second electrode being the end surface electrode on the opposite side to the first electrode of the adjacent secondary battery cell, The plate-shaped laminated portion also serves as the connecting portion, a plurality of the intersecting pieces extending from the plate-shaped laminated portion in the second direction are provided, and the intersecting pieces are connected to the first electrodes of the corresponding secondary battery cells.

11. The battery pack according to any one of claims 1 to 5, wherein: The battery pack includes an insulating plate that covers a surface of the lead plate to insulate the lead plate. The insulating plate includes a discharge hole for allowing discharge from the secondary battery cells to pass therethrough at a position facing the open space.

12. The battery pack according to claim 11, wherein: The discharge hole is in a slit shape.

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