Terminal construction

Abstract

To prevent a short-circuit between secondary batteries even if a fastening member is dropped when detaching a bus bars between cells.SOLUTION: A terminal structure comprises: a cap that is distributed in a secondary battery having a terminal formed on an outer container, and covers the upper part; and a bus bar that is distributed on the cap. The cap comprises: an open part that exposes the terminal; a terminal surface on which one end part of the bus bar is mounted; a fastening tool distribution surface on which the other end part of the bus bar is mounted; a concave part that is formed in the fastening tool distribution surface, and houses a fastening tool without idling; and a protection wall that is stood on the side of the bus bar mounded on the fastening tool housed in the concave part and the fastening tool distribution surface, and is extended in a first direction toward the other end part from the one end part of the bus bar. In the case where the plurality of secondary batteries are arranged and connected by the bus bar between the cells, the protection wall separates the fastening tool connected to a terminal of one secondary battery from the fastening tool connected to the terminal of another secondary battery adjacent to the one secondary battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to terminal structures. [Background technology]

[0002] In recent years, research and development of high-energy-density batteries, such as lithium-ion secondary batteries and non-aqueous electrolyte secondary batteries, has been actively pursued. Secondary batteries (cells) are expected to be used as power sources for vehicles such as hybrid and electric vehicles, as well as for uninterruptible power supplies for mobile phone base stations. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-283256 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The cell terminals of a prismatic lithium-ion secondary battery are formed as protrusions made of, for example, aluminum. The busbars, which are conductors that carry large amounts of current, are joined to the cell terminals by laser welding or the like. When multiple secondary batteries are combined to form a module (battery pack), the inter-cell busbars that connect the secondary batteries must also be made of aluminum that can be welded to the aluminum cell terminals. Multiple secondary batteries are connected in parallel, the inter-cell busbars are placed between adjacent secondary batteries, and then the secondary batteries and inter-cell busbars are joined by laser welding, but this requires large-scale laser welding equipment. Also, when a module is made up of many secondary batteries, the welding work takes a lot of time.

[0005] One method to avoid laser welding of inter-cell busbars is to use a screw structure for the cell terminals, where the inter-cell busbars are fitted into the screw structure of the cell terminals and fastened with nuts. When this structure is adopted, a cap is placed over the top of the secondary battery to prevent excessive force from being applied to the inter-cell busbars and cell terminals during screw fastening.

[0006] Regarding the reuse of secondary batteries, it is common practice to reuse them as a complete battery pack. In this case, the module characteristics of the most degraded secondary battery become the standard, resulting in performance differences between battery packs. Therefore, when reusing secondary batteries after a certain period of use, multiple secondary batteries with the same degree of degradation are selected and reassembled. In this reassembly, if the structure employs laser welding between the cell terminals and inter-cell busbars of the secondary battery, disassembly of the secondary battery unit becomes difficult, making reuse itself difficult.

[0007] If a structure is used in which nuts are fitted into the screw structure of the cell terminals to fasten the inter-cell busbars, the secondary battery can be reused. However, if nuts or other parts fall off during the fastening or loosening process, there is a risk that the fallen nuts or parts may connect adjacent cell terminals, causing a short circuit between secondary batteries.

[0008] Therefore, there is a challenge in preventing short circuits between secondary batteries even if fastening members such as nuts fall off when connecting secondary batteries with inter-cell busbars, or when removing inter-cell busbars connecting secondary batteries. [Means for solving the problem]

[0009] An embodiment of the present invention, a terminal structure, is provided for a secondary battery comprising an outer casing containing a power generation element and a terminal formed on the upper surface of the outer casing. The terminal structure of this embodiment comprises a cap made of resin material, connected to and covering the upper part of the outer casing; a busbar disposed on the cap, having one end welded to the terminal, a connecting piece integrally connected to the one end and rising from the one end, and another end integrally connected to the connecting piece; the cap having an opening that exposes the terminal upward, a terminal surface on which one end of the busbar is placed, a fastener placement surface with a step between it and the terminal surface on which the other end of the busbar is placed, and a fastener placement surface formed to prevent the fastener from rotating freely. The device comprises a recess for housing, a fastener housed in the recess and connected to the terminal by the busbar, and a protective wall erected to the side of the fastener housed in the recess and the busbar placed on the fastener placement surface, extending along a first direction from one end to the other end of the busbar, wherein when multiple secondary batteries are arranged in a row and connected by intercell busbars to form a module, the protective wall separates the fastener connected to the terminal of one secondary battery from the fastener connected to the terminal of another secondary battery located next to that one secondary battery. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an exploded perspective view showing an example of a secondary battery and its terminal structure. [Figure 2] Figure 2 is a perspective view showing a secondary battery with a cap covering the top and busbars positioned on top of the cap. [Figure 3] Figure 3 is a perspective view showing a busbar positioned on a cap, with a hexagonal nut, another example of a fastener, fitted into the recess of the cap covering the top of the secondary battery. [Figure 4] Figure 4 is a perspective view illustrating a state in which a cap with a total of two protective walls in the Y-axis direction covers the top of a secondary battery. [Figure 5]FIG. 5 is a perspective view showing the terminal structure of Embodiment 2 disposed in a secondary battery, and shows a state in which a hexagonal bolt is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 2. [Figure 6] FIG. 6 is a perspective view showing the terminal structure of Embodiment 2 disposed in a secondary battery, and shows a state in which a hexagonal nut is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 2. [Figure 7] FIG. 7 is a perspective view showing the terminal structure of Embodiment 3 disposed in a secondary battery, and shows a state in which a hexagonal bolt is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 3. [Figure 8] FIG. 8 is a cross-sectional view of the terminal structure of Embodiment 3 disposed in a secondary battery, taken along line F1-F1 of FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view for explaining an alternative notch having a triangular cross-section formed in a cap in the terminal structure of Embodiment 3 disposed in a secondary battery. [Figure 10] FIG. 10 is a perspective view showing the terminal structure of Embodiment 3 disposed in a secondary battery, and shows a state in which a hexagonal nut is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 3. [Figure 11] FIG. 11 is a perspective view showing the terminal structure of Embodiment 4 disposed in a secondary battery, and shows a state in which a hexagonal bolt is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 4. [Figure 12] FIG. 12 is a cross-sectional view of the terminal structure of Embodiment 4 disposed in a secondary battery, taken along line F2-F2 of FIG. 11. [Figure 13] FIG. 13 is a perspective view showing the terminal structure of Embodiment 4 disposed in a secondary battery, and shows a state in which a hexagonal nut is disposed as a fastening tool in a recess of a cap of the terminal structure of Embodiment 4. [Figure 14] FIG. 14 is a perspective view showing the terminal structure of Embodiment 4 disposed in a secondary battery, in which the cap has a total of eight snap fits, and shows a state in which a hexagonal bolt is disposed as a fastening tool in a recess of the cap of the terminal structure of Embodiment 4. [Figure 15]FIG. 15 is a perspective view showing a state in which the cap of the terminal structure of Embodiment 4 disposed on the secondary battery has a total of eight snap fits, and a hexagonal nut is disposed as a fastener in the recess of the cap of the terminal structure of Embodiment 4. [Figure 16] FIG. 16 is a perspective view showing a state in which the terminal structure of Embodiment 1 is disposed on a secondary battery of a modification in which the terminal is a bolt terminal, and a hexagonal bolt is disposed as a fastener in the recess of the cap of the terminal structure of Embodiment 1. [Figure 17] FIG. 17 is a perspective view showing a state in which the terminal structure of Embodiment 2 is disposed on a secondary battery of a modification in which the terminal is a bolt terminal, and a hexagonal bolt is disposed as a fastener in the recess of the cap of the terminal structure of Embodiment 2. [Figure 18] FIG. 18 is a perspective view showing a state in which the terminal structure of Embodiment 3 is disposed on a secondary battery of a modification in which the terminal is a bolt terminal, and a hexagonal bolt is disposed as a fastener in the recess of the cap of the terminal structure of Embodiment 3. [Figure 19] FIG. 19 is a perspective view showing a state in which the terminal structure of Embodiment 4 is disposed on a secondary battery of a modification in which the terminal is a bolt terminal, and a hexagonal bolt is disposed as a fastener in the recess of the cap of the terminal structure of Embodiment 4. [Figure 20] FIG. 20 is a perspective view showing a plurality of secondary batteries on which a terminal structure is disposed, a case that houses the secondary batteries to form a module, and an inter-cell bus bar that connects adjacent secondary batteries. [Figure 21] FIG. 21 is a cross-sectional view showing a state in which a module is formed by connecting the positive terminal of one secondary battery and the negative terminal of another adjacent secondary battery by an inter-cell bus bar. [Figure 22] FIG. 22 is a cross-sectional view explaining a state in which a protective wall prevents a fixed nut with a washer that has been removed and dropped from connecting between adjacent terminals and causing a short circuit. [Figure 23] FIG. 23 is a cross-sectional view explaining the required height of the protective wall to prevent a dropped fixed nut with a washer from simultaneously contacting adjacent terminals. [Modes for carrying out the invention]

[0011] The secondary battery 10 shown in Figure 1 is also called a battery cell or single cell. The secondary battery 10 is, for example, a non-aqueous electrolyte secondary battery such as a lithium-ion battery, and comprises, for example, a flat or substantially rectangular outer container 2 made of aluminum or an aluminum alloy, and a power generation element 27 housed in the outer container 2 together with a non-aqueous electrolyte or an aqueous electrolyte.

[0012] In the following explanation, we will use a Cartesian coordinate system with X, Y, and Z axes. The X-axis direction includes both the +X and -X directions. The Y-axis direction includes both the +Y and -Y directions. The Z-axis direction includes both the +Z and -Z directions. For example, the X-Y axis plane is the horizontal plane, and the Z-axis direction is the vertical direction.

[0013] The outer container 2 has a bottomed rectangular cylindrical container body 20 and a rectangular plate-shaped lid 21 attached to an opening (not shown) of the container body 20 by melting or the like. Two types of terminals, a positive electrode terminal 23 and a negative electrode terminal 24, are arranged on the upper surface 22 of the lid 21 in areas on both sides in the longitudinal direction (X-axis direction) of the secondary battery 10. The secondary battery 10 is also equipped on the upper surface 22 with a lavage chutes 25 for discharging gas generated inside the outer container 2 and an injection port 26 for injecting a non-aqueous electrolyte into the outer container 2.

[0014] The positive terminal 23 and negative terminal 24 for current input and output are attached to the cover 21 by crimping or by being cast into the cover 21 during its molding process. The cover 21 and the positive terminal 23 and negative terminal 24 are electrically insulated from each other. The positive terminal 23 and negative terminal 24 are formed, for example, in a substantially flat plate shape.

[0015] The positive electrode of the power generation element 27, shown in a simplified dashed line, is electrically connected to the positive electrode terminal 23. The negative electrode of the power generation element 27 is electrically connected to the negative electrode terminal 24. The power generation element 27 includes, for example, a group of recurring electrodes.

[0016] The labture 25 has an X-shaped groove provided in the thin-walled portion located between the positive terminal 23 and the negative terminal 24 of the lid 21.

[0017] The terminal structure 12 of this embodiment 1, which is arranged in the secondary battery 10, comprises a cap 3 made of resin material, connected to the upper part of the outer casing 2 and covering the upper part, and a busbar 4 arranged on the cap 3 and having one end 41 which is welded to, for example, the positive electrode terminal 23 using brazing material, a connecting piece 42 which is integrally connected to the one end 41 and rises up from the one end 41, and the other end 43 which is integrally connected to the connecting piece 42. The busbar 4 is also connected to the negative electrode terminal 24. In other words, two busbars 4 are arranged on the cap 3.

[0018] The resin material, such as plastic, used to form cap 3 is not particularly limited, as long as it does not have electrical conductivity and is corrosion-resistant to electrolytes. Specific examples of resin materials include polypropylene, polyethylene (e.g., high-density polyethylene (HDPE) or low-density polyethylene (LDPE)), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), etc.

[0019] The cap 3 comprises a base 30 whose overall shape is a rectangle in plan view with its longitudinal direction parallel to the longitudinal direction (X-axis direction) of the secondary battery 10, a skirt portion 31 hanging down in the outer peripheral region of the lower surface of the base 30, a lubricant exposure opening 32 formed through the center of the upper surface of the base 30, and two openings 33 formed on the upper surface of the base 30 in regions on both sides of the lubricant exposure opening 32 in the longitudinal direction (X-axis direction) of the cap 3.

[0020] The upper part of the secondary battery 10 is fitted into the roughly rectangular parallelepiped space enclosed by the lower surface of the base 30 and the skirt portion 31. Then, for example, the area of ​​the upper surface 22 of the lid 21, excluding the positive terminal 23, the liquid filling port 26, the lubrication valve 25, and the negative terminal 24, is bonded to the lower surface of the base 30 with an adhesive, and the cap 3 is placed over the upper part of the secondary battery 10 to connect them. The adhesive is, for example, a two-component curing epoxy resin adhesive, but is not limited to this, and may also be an ultra-thin double-sided tape. Note that the connection between the cap 3 and the secondary battery 10 is not limited to the example using an adhesive.

[0021] For example, a "+" mark 300, indicating the positive terminal 23 side, is printed on the -X side of the upper surface of the base 30. Also, for example, the area around the lubricating opening 32 is surrounded on all four sides by walls erected on the upper surface of the base 30.

[0022] Around the two openings 33 formed on the upper surface of the base 30, for example, a rectangular frame 330, integrally formed on the upper surface of the base 30, and two protective walls 34, erected at the two upper ends of the frame 330 in the Y-axis direction and extending in the longitudinal direction (X-axis direction) of the base 30, are provided. For clarity, the protective walls 34 are shown as dashed lines in Figure 1.

[0023] The area inside the frame 330 on the upper surface of the base 30 is provided with, for example, a step, and includes a fastener placement surface 304 located at a higher position on the upper surface of the base 30, and a terminal surface 306 located at a lower position than the fastener placement surface 304 and at the same height as the area outside the frame 330 on the upper surface of the base 30.

[0024] An opening 33 is formed in the terminal surface 306, penetrating the base 30 in the thickness direction. The opening 33 is, for example, roughly rectangular in plan view, and is sized to expose the entire positive terminal 23 or negative terminal 24 upwards.

[0025] On the fastener placement surface 304, for example, a hexagonal recess 305 is formed by cutting out a section in the thickness direction of the base 30. The head 370 of a hexagonal bolt 37, which is an example of a fastener as shown in Figures 1 and 2, can be fitted into the recess 305. Furthermore, for example, the head 370 of the hexagonal bolt 37 is designed not to protrude upward from the recess 305.

[0026] With the cap 3 placed over the upper side of the secondary battery 10, the positive terminal 23 is exposed from one opening 33 of the base 30 of the cap 3, the lubricant 25 is exposed from the lubricant exposure opening 32, and the negative terminal 24 is exposed from the other opening 33 of the base 30.

[0027] The two busbars 4 shown in Figure 1 are housed one in each of the two frames 330. The busbars 4 are made of aluminum or an aluminum alloy and are formed in a rectangular shape in plan view. The busbars 4 are configured in a roughly Z shape in side view when viewed from the Y-axis direction. More specifically, the busbars 4 have, for example, a flat end 41 which is welded and fixed to the positive terminal 23, a connecting piece 42 which is bent at a right angle from the end 41 and rises in the direction away from the terminal surface 306 (+Z direction), and a plate-shaped other end 43 which is connected to the connecting piece 42 and parallel to the end 41. Note that although the connecting piece 42 is bent at a right angle to the end 41 and the other end 43, it is not necessarily required to be at a right angle.

[0028] A counterbore hole 411 for laser welding using brazing material is formed through one end 41 at approximately the center of the end. The busbar 4 is connected to the other end 43 and the one end 41 by a connecting piece 42, thereby corresponding to the stepped fastener placement surface 304 and terminal surface 306 of the base 30.

[0029] For example, in the example shown in Figure 1, an engaging projection 306a is provided on the upper surface of the terminal surface 306 of the base 30 of the cap 3, and an engaging hole 410 that engages with the engaging projection 306a is formed in one end 41 of the busbar 4. When the engaging projection 306a engages with the engaging hole 410, the horizontal displacement of the busbar 4 on the base 30 is restricted.

[0030] As shown in Figure 2, for example, a through hole 430 is formed at approximately the center of the other end 43 of the busbar 4, through which the male threaded portion 371 of a hexagonal bolt 37 is inserted. The head 370 of the hexagonal bolt 37 is fitted into a recess 305 formed on the fastener placement surface 304 shown in Figure 1. With the head 370 housed in the recess 305, the hexagonal bolt 37 is not in a state where it can rotate freely within the recess 305. Note that in Figure 2, some of the components, such as the engaging projection 306a shown in Figure 1, are omitted.

[0031] Then, as shown in Figure 2, the through hole 430 of the busbar 4 is inserted through the male threaded portion 371 of the hexagonal bolt 37, the other end 43 is placed on the fastener placement surface 304 shown in Figure 1, and the one end 41 is placed on the terminal surface 306. In this state, the positive terminal 23 or negative terminal 24 exposed from the counterbore 411 of the one end 41 and the opening 33 of the base 30 of the cap 3 is welded (for example, laser brazing) to the one end 41 of the busbar 4. Note that the brazing material is omitted in Figure 2. The male threaded portion 371 of the hexagonal bolt 37 protrudes a predetermined length upward from the other end 43 of the busbar 4, and with an inter-cell busbar (not shown) inserted into the male threaded portion 371, a fixing nut 373 with a washer 374 can be fastened to the male threaded portion 371. Note that the fixing nut 373 is a hexagonal nut. When the fixing nut 373 is fastened to the hexagonal bolt 37, the busbar 4 electrically connects the hexagonal bolt 37, which is the fastener, to the positive terminal 23. Similarly, the busbar 4 electrically connects the hexagonal bolt 37, which is the fastener, to the negative terminal 24.

[0032] For example, when the other end 43 of the busbar 4 is placed on the fastener placement surface 304 within the frame 330 and one end 41 is placed on the terminal surface 306, the upper surface of the other end 43 of the busbar 4 and the upper end surface of the frame 330 are substantially flush.

[0033] For example, instead of the hexagonal bolt 37 shown in Figures 1 and 2, a hexagonal nut 38, which is another example of a fastener shown in Figure 3, may be fitted into the recess 305 of the fastener placement surface 304 of the base 30. Note that the hexagonal nut 38 is designed so that it does not protrude upward from the recess 305. The hexagonal nut 38 housed in the recess 305 will not rotate freely within the recess 305.

[0034] With the hexagonal nut 38 shown in Figure 3 fitted into the recess 305 formed on the fastener placement surface 304 shown in Figure 1, the other end 43 of the busbar 4 is placed on the fastener placement surface 304 of the base 30, and one end 41 is placed on the terminal surface 306. Then, the negative electrode terminal 24 exposed from the counterbore hole 411 of the one end 41 shown in Figure 3 and the opening 33 of the base 30 of the cap 3 and the one end 41 of the busbar 4 are laser-welded using brazing material. Furthermore, with an inter-cell busbar (not shown) placed on top of the busbar 4, the fixing bolt 386 can be screwed through the through hole 430 into the hexagonal nut 38 located below the busbar 4 and fitted into the recess 305. Note that the fixing bolt 386 may be one with a washer.

[0035] As shown in Figures 1 and 2, the protective wall 34 is integrally erected from the upper end of the frame 330 on the side in the Y-axis direction of the busbar 4, which is placed on the surface 304 for fasteners, such as the hexagonal bolt 37 housed in the recess 305, and extends along the first direction (X-axis direction) from one end 41 to the other end 43 of the busbar 4. For example, the length of the protective wall 34 in the X-axis direction is approximately the same as, or longer than, the length of the busbar 4 in the X-axis direction.

[0036] In the examples shown in Figures 1 and 2, two protective walls 34 are arranged opposite each other in the Y-axis direction on the side of the busbar 4, which is placed on the fastener placement surface 304 and houses the hexagonal bolt 37 in the recess 305 on the positive terminal 23 side, and two protective walls 34 are arranged opposite each other in the Y-axis direction on the side of the busbar 4, which is placed on the fastener placement surface 304 and houses the hexagonal bolt 37 in the recess 305 on the negative terminal 24 side. In other words, in the examples shown in Figures 1 and 2, the cap 3 is equipped with a total of four protective walls 34.

[0037] Figure 4 shows a modified example of the cap 3 in the terminal structure 12 of Embodiment 1. In this modified example in Figure 4, one protective wall 34 is provided only on one side (+Y direction side) of the busbar 4, which is placed on the fastener placement surface 304 and contains, for example, a hexagonal nut 38 housed in the recess 305 on the positive terminal 23 side, and one protective wall 34 is provided only on one side of the busbar 4, which is placed on the fastener placement surface 304 and contains, for example, a hexagonal nut 38 housed in the recess 305 on the negative terminal 24 side. In other words, in the modified example shown in Figure 4, the cap 3 is equipped with a total of two protective walls 34. Note that in Figure 4, a hexagonal bolt 37 may be provided in the recess 305 as a fastener.

[0038] As shown in Figure 1, the cap 3 is provided with, for example, two plate-shaped separators 307 that hang down from the lower surface of the base 30 together with the skirt portion 31. The separators 307 are formed from a material whose outer surface is electrically insulating. The separators 307 serve to partition adjacent secondary batteries 10 when multiple secondary batteries 10 are connected in parallel in the Y-axis direction as shown in Figure 1. Note that the cap 3 does not necessarily have to be provided with separators 307.

[0039] Figure 5 shows the terminal structure 12A of Embodiment 2. The terminal structure 12A is a modification of the configuration of the terminal structure 12 of Embodiment 1 shown in Figures 1 and 2. Components similar to those of the terminal structure 12 are denoted by the same reference numerals and their descriptions are omitted. On the upper surface of the base 30 of the cap 3A of the terminal structure 12A, in addition to the two protective walls 34 on the positive terminal 23 side (-X direction side), there are two second protective walls 342 erected at the two upper ends in the X-axis direction of the frame 330 and extending in the short direction (Y-axis direction) of the base 30. The two second protective walls 342 and the two protective walls 34 are independent of each other. Furthermore, the protective wall 34 extending in the first direction (X-axis direction) and the second protective wall 342 extending in the second direction (Y-axis direction) are orthogonal to each other. Therefore, the hexagonal bolt 37 housed in the recess 305 (see Figure 2) on the positive terminal 23 side and the busbar 4 placed on the fastener placement surface 304 are surrounded by two protective walls 34 and two second protective walls 342. The structure on the negative terminal 24 side is the same as described above.

[0040] In the terminal structure 12A of Embodiment 2 shown in Figure 5, a hexagonal bolt 37 is used as a fastener. For example, in the terminal structure 12A of Embodiment 2, as shown in Figure 6, a hexagonal nut 38, which is another example of a fastener, may be fitted into a recess 305 formed on the fastener placement surface 304 (see Figure 1) of the cap 3A, and the busbar 4 may be arranged on the cap 3A.

[0041] Figure 7 shows the terminal structure 12B of Embodiment 3. The terminal structure 12B is a modification of the configuration of the terminal structure 12 of Embodiment 1 shown in Figures 1 and 2. Components similar to those of the terminal structure 12 are denoted by the same reference numerals and their descriptions are omitted. The protective wall 34 of the cap 3B of the terminal structure 12B has a notch 344 formed in the protective wall 34 that is recessed in the thickness direction (Y-axis direction) of the protective wall 34 and extends linearly along the extension direction (X-axis direction) of the protective wall 34.

[0042] Figure 8 is a cross-sectional view taken along the line F1-F1 in Figure 7. Note that Figure 7 shows the state where the fixing nut 373 is not attached to the hexagonal bolt 37, while Figure 8 shows the state where the fixing nut 373 is attached to the hexagonal bolt 37. As shown in Figure 8, the notch 344 is formed in a V-shape in cross-section, for example, extending from the outer surface to the inner surface of the protective wall 34. Also, for example, the tip of the notch 344 is located on the boundary line between the protective wall 34 and the frame 330. In the example in Figure 7, the notch 344 is formed continuously from end to end in the X-axis direction on the outer surface of the protective wall 34. Note that the notch 344 may be formed on only two protective walls 34 on either the +Y direction or the -Y direction.

[0043] The notch is not limited to the V-shaped notch 344 described above, but as shown in Figure 9, for example, a notch 345 may be formed in a triangular cross-section extending from the outer surface to the inner surface of the protective wall 34. The tip of the notch 345 in the cross-section is located on the boundary line between the protective wall 34 and the frame 330. The angle of the notch 345 is, for example, 45 degrees.

[0044] The notch 344 is not limited to the example shown in Figure 7, where it is formed as a single continuous line from end to end in the X-axis direction on the outer surface of the protective wall 34. That is, multiple notches 344 may be formed as a single dashed line continuously from end to end in the X-axis direction on the outer surface of the protective wall 34.

[0045] In the terminal structure 12B of Embodiment 3 shown in Figure 7, a hexagonal bolt 37 is used as a fastener. As shown in Figure 10, in the terminal structure 12B of Embodiment 3, a hexagonal nut 38, which is another example of a fastener, may be fitted into a recess 305 formed on the fastener placement surface 304 (see Figure 1) of the cap 3B, and the other end 43 of the busbar 4 may be placed on the fastener placement surface 304 of the base 30, while the one end 41 is placed on the terminal surface 306.

[0046] Figure 11 shows the terminal structure 12C of Embodiment 4. The terminal structure 12C is a modification of the configuration of the terminal structure 12 shown in Figures 1 and 2, and components similar to those of the terminal structure 12 are denoted by the same reference numerals and their description is omitted. The cap 3C of the terminal structure 12C is provided with a snap fit 347 on the inner surface of its frame 330 or the inner surface of its protective wall 34, which presses one end 41 of the busbar 4 downward toward the terminal surface 306.

[0047] The snap-fit ​​347 is formed, for example, one on each inner surface of the frame 330 in the Y-axis direction. The snap-fit ​​347 comprises a notched hole 347a formed by cutting a rectangular notch in the thickness direction (Y-axis direction) of the side wall of the frame 330, and a slope portion 347b disposed within the notched hole 347a and having an inclined surface that slopes from top to bottom.

[0048] Figure 12 is a cross-sectional view taken along the line F2-F2 in Figure 11. As shown in Figure 12, when the busbar 4 is pushed into the frame 330 from above, each slope portion 347b elastically deforms toward the outer surface side in the Y-axis direction of the cap 3C, allowing the busbar 4 to pass through and then returning to its natural state. As shown in Figure 12, the busbar 4 is then sandwiched from above and below between the lower surfaces of the two slope portions 347b and the terminal surface 306 of the base 30. Note that 412 in Figure 12 is a brazing material 412 used to weld the negative terminal 24 and one end 41 of the busbar 4. The snap-fit ​​347 shown in Figures 11 and 12 is located, for example, on a virtual line extending in the Y-axis direction, passing through the center of the counterbore hole 411 formed in one end 41 of the busbar 4. In the example shown in Figure 11, the cap 3C of the terminal structure 12C is equipped with a total of four snap-fit ​​347.

[0049] In the terminal structure 12C of Embodiment 4 shown in Figure 11, a hexagonal bolt 37 is used as a fastener. As shown in Figure 13, in the terminal structure 12C of Embodiment 4, a hexagonal nut 38, which is another example of a fastener, may be fitted into a recess 305 formed on the fastener placement surface 304 (see Figure 1) of the cap 3C, with the other end 43 of the busbar 4 placed on the fastener placement surface 304 of the base 30 and one end 41 placed on the terminal surface 306.

[0050] The number and placement of the snap-fits 347 are not limited to the example shown in Figure 11. For example, as shown in Figures 14 and 15, two snap-fits 347 may be formed on each inner surface of the frame 330 in the Y-axis direction. In Figures 14 and 15, for example, a virtual line extending in the Y-axis direction through the center of the counterbore hole 411 of the busbar 4 is set to pass through the midpoint between two snap-fits 347 aligned in the X-axis direction. The cap 3C of the terminal structure 12C of Embodiment 4 shown in Figures 14 and 15 is equipped with a total of eight snap-fits 347. Figure 14 shows a state in which a hexagonal bolt 37 is placed on the cap 3C as a fastener, and Figure 15 shows a state in which a hexagonal nut 38 is placed on the cap 3C as a fastener.

[0051] The secondary battery 10A shown in Figure 16 is a modified example of the secondary battery 10 shown in Figures 1 and 2. Components similar to those of the secondary battery 10 are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 16, the positive terminal 23a and the negative terminal 24a of the secondary battery 10A are columnar bolt terminals that extend in the +Z direction from the upper surface 22 of the outer casing 2 shown in Figure 1. The positive terminal 23a and the negative terminal 24a protrude upward from the two openings 33 (see Figure 1) of the cap 3 that constitute the terminal structure 12 of Embodiment 1, and are exposed from the openings 33.

[0052] In Figure 16, the through-hole 430 of the busbar 4 is inserted through the male threaded portion 371 of the hexagonal bolt 37, with the other end 43 resting on the fastener placement surface 304 and one end 41 resting on the terminal surface 306. In this state, the negative terminal 24a, which protrudes upward from the opening 33 of the base 30 of the cap 3 and the counterbore 411 of one end 41, and one end 41 of the busbar 4 are laser-welded using a brazing material (not shown). Note that in the example shown in Figure 16, a hexagonal nut 38 shown in Figure 3 may be used as a fastener instead of the hexagonal bolt 37.

[0053] Figure 17 shows the terminal structure 12A of Embodiment 2 installed on a modified secondary battery 10A. The hexagonal bolt 37 housed in the recess 305 on the positive terminal 23a side and the busbar 4 placed on the fastener placement surface 304 are surrounded by two protective walls 34 and two second protective walls 342. The structure on the negative terminal 24a side is the same as described above. In the example shown in Figure 17, a hexagonal nut 38 as shown in Figure 3 may be used as a fastener instead of the hexagonal bolt 37.

[0054] Figure 18 shows the terminal structure 12B of Embodiment 3 installed on a modified secondary battery 10A. Two protective walls 34 are erected on the sides of the busbar 4, which is placed on the fastener placement surface 304 and houses the hexagonal bolt 37 in the recess 305 on the positive terminal 23a side, which is a bolt terminal. The two protective walls 34 are easily bent in the Y-axis direction by notches 344. The structure on the negative terminal 24a side, which is a bolt terminal, is the same as described above. In the example shown in Figure 18, a hexagonal nut 38, which is another example of a fastener as shown in Figure 3, may be used instead of the hexagonal bolt 37.

[0055] Figure 19 shows the terminal structure 12C of Embodiment 4 installed on a modified secondary battery 10A. Two protective walls 34 are erected on the sides of the busbar 4, which is placed on the fastener placement surface 304 and houses the hexagonal bolt 37 in the recess 305 on the positive terminal 23a side, which is a bolt terminal. Furthermore, one end 41 of the busbar 4, which is welded to the positive terminal 23a protruding upward from the opening 33 (see Figure 1), is pressed toward the terminal surface 306 below by the snap-fit ​​347 provided on the cap 3C. The structure on the negative terminal 24a side, which is a bolt terminal, is the same as described above.

[0056] The secondary batteries 10 shown in Figures 1 and 2 are housed, for example, in a resin case 51 shown in Figure 20, and inter-cell busbars 53 connect the positive terminal 23 of one secondary battery 10 to the negative terminal 24 of another secondary battery 10 adjacent to it, so that adjacent secondary batteries 10 have a desired voltage and current. A module 1 is formed by multiple secondary batteries 10. Module 1 is also called a battery pack 1. In a module 1 formed by housing multiple secondary batteries 10 in a resin case 51, at least one of a series connection structure in which the multiple secondary batteries 10 are electrically connected in series, and a parallel connection structure in which the multiple secondary batteries 10 are electrically connected in parallel are formed.

[0057] The resin case 51 is formed from an electrically insulating material. Examples of materials for forming the resin case 51 include resins such as polyphenylene ether, polycarbonate, and polybutylene terephthalate.

[0058] The resin case 51 comprises a pair of side walls 512 facing each other in the longitudinal direction (Y-axis direction) of the resin case 51, a pair of side walls 513 facing each other in the short direction (X-axis direction) of the resin case 51, and a bottom plate 515. Each side wall 512, each side wall 513 and the bottom plate 515 are connected integrally, for example.

[0059] As an example, the resin case 51 comprises 11 partition walls 516. Each partition wall 516 is positioned between a pair of side walls 512 in the Y-axis direction, and the interior of the resin case 51 is divided into 12 storage chambers 517 in the Y-axis direction by the 11 partition walls 516, which are spaced equally apart from each other. The partition walls 516 are formed from a material whose outer surface is electrically insulating.

[0060] The inter-cell busbars 53 shown in Figures 20 and 21 are, for example, made of aluminum or an aluminum alloy formed in a rectangular flat plate shape, and have, for example, one bolt insertion hole 530 formed on each side in the longitudinal direction (Y-axis direction).

[0061] Each of the housing compartments 517 of the resin case 51 houses one secondary battery 10. A hexagonal bolt 37 connected to the positive terminal 23 of one secondary battery 10 via a busbar 4 is connected to a hexagonal bolt 37 connected to the negative terminal 24 of an adjacent secondary battery 10 via a busbar 4, and is connected by an inter-cell busbar 53. The negative terminal 24 of the same secondary battery 10 is connected to the positive terminal 23 of the adjacent secondary battery 10 on the opposite side via an inter-cell busbar 53. Positive terminals 23 not connected by an inter-cell busbar 53 are connected to a positive power input / output terminal (not shown) via a circuit. Similarly, negative terminals 24 not connected by an inter-cell busbar 53 are connected to a negative power input / output terminal (not shown) via a circuit. The positive power input / output terminals and negative power input / output terminals (not shown) are connected to a charging power supply and load, enabling the charging and use of module 1.

[0062] In this way, multiple secondary batteries 10 are connected in series, for example, by multiple inter-cell busbars 53 to form module 1. In module 1, which includes multiple secondary batteries 10 that are electrically connected in parallel, the multiple secondary batteries 10 can be electrically connected, for example, by connecting the negative terminals 24 together by inter-cell busbars 53 and the positive terminals 23 together by inter-cell busbars 53.

[0063] The connection between the positive terminal 23 of one secondary battery 10 and the negative terminal 24 of an adjacent secondary battery 10 using an inter-cell busbar 53 will be explained in detail. In order to span the inter-cell busbar 53 between a pair of secondary batteries 10, the opposing protective walls 34 of one secondary battery 10 and the other secondary battery 10 located next to it are cut from the cap 3 as necessary, as shown in Figure 21. This cutting can be done using a tool such as a cutter, or the worker can apply force to break and cut off the protective wall 34. In Figure 21, the protective wall 34 that has been cut off and is no longer on the cap 3 is shown by a dashed line.

[0064] Alternatively, a terminal structure 12 equipped with a modified cap 3 as shown in Figure 4, which has a protective wall 34 on only one side in the Y-axis direction, may be provided on the secondary battery 10. Alternatively, the terminal structure 12B of Embodiment 3 shown in Figure 7 may be provided on the secondary battery 10. In this case, the protective wall 34 of the cap 3B of the terminal structure 12B shown in Figure 7 has a notch 344 formed linearly along the extension direction (X-axis direction) of the protective wall 34, which is recessed in the thickness direction (Y-axis direction) of the protective wall 34. Therefore, when cutting the opposing protective walls 34 from the cap 3B as needed for one secondary battery 10 and another secondary battery 10 located next to it, in order to span the inter-cell busbar 53 between a pair of secondary batteries 10, it is possible to easily break off the protective wall 34 to be cut off, starting from the notch 344.

[0065] As shown in Figure 21, with the protective wall 34 between adjacent secondary batteries 10 removed as needed, one bolt insertion hole 530 (see Figure 20) of the inter-cell busbar 53 is inserted through a hexagonal bolt 37 on the positive terminal 23 side of one secondary battery 10, and a fixing nut 373 with a washer 374 is screwed onto the hexagonal bolt 37. The other bolt insertion hole 530 of the inter-cell busbar 53 is inserted through a hexagonal bolt 37 on the negative terminal 24 side of another adjacent secondary battery 10, and a fixing nut 373 with a washer 374 is screwed onto the hexagonal bolt 37, thereby connecting the positive terminal 23 of one secondary battery 10 to the busbar 4, hexagonal bolt 37, fixing nut 373, and the negative terminal 24 of another secondary battery 10 located next to the inter-cell busbar 53. Note that in Figure 21, a part of module 1 is shown in cross-sectional view.

[0066] Even when the hexagonal nut 38 shown in Figure 3 is fitted into the recess 305, the connection between the secondary batteries 10 by the inter-cell busbar 53 is performed in substantially the same manner as described above. That is, the fixing bolt 386 shown in Figure 3 is inserted through one of the bolt insertion holes 530 of the inter-cell busbar 53 shown in Figure 21, and the fixing bolt 386 is screwed into the hexagonal nut 38 on the positive terminal 23 side of the secondary battery 10. Similarly, another fixing bolt 386 inserted through the other bolt insertion hole 530 of the inter-cell busbar 53 is screwed into the hexagonal nut 38 on the negative terminal 24 side of another adjacent secondary battery 10.

[0067] Furthermore, when the terminal structure 12C of Embodiment 4 shown in Figure 11 is installed on the secondary battery 10, when the fixing nut 373 is fastened and tightened on the hexagonal bolt 37, a downward pressing force is applied to the other end 43 of the busbar 4, and an upward lifting moment is applied to the one end 41. In the terminal structure 12C of Embodiment 4, since the cap 3C is equipped with a snap fit 347, the snap fit 347 can press the one end 41 of the busbar 4 toward the terminal surface 306 so that, for example, the weld made by the brazing material 412 (not shown in Figure 11, see Figure 12) between the negative electrode terminal 24 and the one end 41 of the busbar 4 does not come undone due to this moment.

[0068] As described above, the two adjacent secondary batteries 10 shown in Figure 21 are electrically connected by an inter-cell busbar 53. In module 1, a protective wall 34 separates a hexagonal bolt 37 connected via a busbar 4 to, for example, the negative terminal 24 of one secondary battery 10, and a hexagonal bolt 37 connected via a busbar 4 to, for example, the positive terminal 23 of another secondary battery 10 located next to the first secondary battery 10 and not electrically connected by an inter-cell busbar 53. For the purposes of the explanation below, the hexagonal bolts 37 arranged from the +Y direction to the -Y direction in Figures 21 and 22 will be given provisional numbers. That is, in Figures 21 and 22, the hexagonal bolt 37 located furthest towards the -Y direction will be referred to as the first hexagonal bolt 37, and the hexagonal bolts 37, 3rd, and 4th will be referred to in order toward the -Y direction. As shown in Figure 20, for example, the first hexagonal bolt 37 connected to the positive terminal 23 by a busbar 4, and the second hexagonal bolt 37 connected to the negative terminal 24 by a busbar 4, are connected by an inter-cell busbar 53. The second hexagonal bolt 37 and the third hexagonal bolt 37 are not connected by an inter-cell busbar 53, and are separated from each other by a protective wall 34. Also, the third hexagonal bolt 37 connected to the positive terminal 23 by a busbar 4, and the fourth hexagonal bolt 37 connected to the negative terminal 24 by a busbar 4, are connected by an inter-cell busbar 53. Note that the secondary batteries 10 shown in Figures 21 and 22 are also numbered from the first to the fourth secondary batteries 10 in order from the +Y direction to the -Y direction.

[0069] The following describes the effects of the terminal structure 12 of this embodiment 1 when the connection between the positive terminal 23 of one secondary battery 10 (see Figure 20) and the negative terminal 24 of the adjacent secondary battery 10 (see Figure 20), which is connected by a hexagonal bolt 37, a fixing nut 373 with a washer 374, and an inter-cell busbar 53, is released.

[0070] For example, in Figure 22, the fixing nut 373 that was fastened to the hexagonal bolt 37 of the first secondary battery 10, which is located furthest to the -Y direction, is turned by a worker or the like and removed from the first hexagonal bolt 37.

[0071] In this case, the worker may accidentally drop the fixing nut 373 on module 1 while carrying it out. However, as shown in Figure 22, in module 1, a protective wall 34 separates a hexagonal bolt 37 connected to the negative terminal 24 of one secondary battery 10 from a hexagonal bolt 37 connected to the positive terminal 23 of another secondary battery 10 located next to the first secondary battery 10 and not electrically connected by an inter-cell busbar 53. In other words, in the example shown in Figure 22, it is prevented that the negative terminal 24 of the secondary battery 10 with a cap 3 having a second hexagonal bolt 37 and the positive terminal 23 of the secondary battery 10 with a cap 3 having a third hexagonal bolt 37 will not be connected by the dropped fixing nut 373 and cause a short circuit. This is because the protective wall 34 prevents the dropped fixing nut 373 from simultaneously contacting the second hexagonal bolt 37 and fixing nut 373, and the third hexagonal bolt 37 and fixing nut 373.

[0072] Furthermore, in order to more reliably prevent a short circuit caused by the fallen fixing nut 373 by the protective wall 34, the height H of the protective wall 34 is set as described below with reference to Figures 22 and 23. Figure 23 shows a secondary battery 10 with a cap 3 having the second hexagonal bolt 37 as shown in Figure 22, and a secondary battery 10 with a cap 3 having the third hexagonal bolt 37 as shown.

[0073] (An example of protective wall height) When the distance L in the Y-axis direction between, for example, the positive terminal 23 of one secondary battery 10 and, for example, the negative terminal 24 of another secondary battery 10 located next to the first secondary battery 10, as shown in Figure 23, is smaller than the maximum dimension B of the washer 374 and the fixing nut 373, the height H of the protective wall 34 is higher than the fixing nut 373, thereby more reliably preventing the occurrence of the short circuit.

[0074] Specifically, the hexagonal bolts 37 shown in Figures 1 and 2 are located, for example, on a virtual line extending in the X-axis direction, passing through the centers of the negative terminal 24 and positive terminal 23 of the secondary battery 10. Therefore, the distance L in the Y-axis direction between the negative terminal 24 of the second secondary battery 10 and the positive terminal 23 of the third secondary battery 10 shown in Figure 23 is the distance L in the Y-axis direction between the center of the negative terminal 24 of the second secondary battery 10 and the center of the positive terminal 23 of the third secondary battery 10. In other words, as shown in Figure 23, it is the distance L in the Y-axis direction between the center of the second hexagonal bolt 37 and the center of the third hexagonal bolt 37.

[0075] Furthermore, the maximum dimension B of the washer 374 and fixing nut 373 is the maximum dimension from one corner vertex of the hexagonal fixing nut 373 to the outer edge of the lower surface of the washer 374. Here, let the height a of the fixing nut 373 + the height c of the washer 374 be x as shown in Figure 23. Also, let the diagonal distance b of the hexagonal fixing nut 373 + (outer diameter d of the washer 374 - diagonal distance b of the fixing nut 373) / 2 = y. Then, by the Pythagorean theorem, the maximum dimension B = (x 2 +y 2 ) 1 / 2 This is the result.

[0076] If, for example, the distance L in the Y-axis direction between the center of the second hex bolt 37 and the center of the third hex bolt 37 shown in Figure 23 is equal to the maximum dimension B of the washer 374 and the fixing nut 373, then the height H of the protective wall 34 is higher than the height of the fixing nut 373 (height of the top surface of the fixing nut 373). This makes it more reliable to prevent the falling fixing nut 373 from simultaneously contacting the second and third hex bolts 37, thereby more reliably preventing the occurrence of the short circuit.

[0077] (Another example of protective wall height) The following describes the required height H of the protective wall 34 to more reliably prevent a fallen fixing nut 373 from simultaneously contacting the second and third hexagonal bolts 37 when the distance L in the Y-axis direction between, for example, the positive terminal 23 of one secondary battery 10 and for example, the negative terminal 24 of another secondary battery 10 located next to the first secondary battery 10, i.e., the distance L in the Y-axis direction between the center of the second hexagonal bolt 37 and the center of the third hexagonal bolt 37, is greater than or equal to the maximum dimension B of the washer 374 and fixing nut 373. Note that Figure 23 shows a state in which the fixing nut 373 with the removed washer 374 has come into contact with the second and third fixing nut 373. Furthermore, the following explanation and Figure 23 describe the case where, as a prerequisite, the fallen fixing nut 373 is located at a position where a right triangle with y' (the distance in the Y-axis direction from point O to the adjacent fixing nut on the -Y side) as the base, x as the height, and point O as one of the vertices is similar to a right triangle with z as the base, (he) as the height, and point O as one of the vertices (see Figure 23).

[0078] As shown in Figure 23, a = height of the fixing nut 373, c = height of the washer 374, b = diagonal distance of the fixing nut 373, d = outer diameter of the washer 374, B = maximum dimensions of the washer 374 and fixing nut 373, f = thickness of the protective wall 34, and e = thickness of the inter-cell bus bar 53.

[0079] First, from the similarity condition shown in Figure 23, x:(he)=y:z holds. Therefore, as shown in Figure 23, h=(x×z / y)+e, and the height H>h=(x×z / y)+e of the protective wall 34 required to more reliably prevent the fallen fixing nut 373 from simultaneously contacting the second hexagonal bolt 37 and the third hexagonal bolt 37 is given by equation (1). Also, as shown in Figure 23, z=y-(B / 2+f) holds, so by combining this with equation (1), the required height H of the protective wall 34 can be calculated.

[0080] For example, assume that the distance L in the Y-axis direction between the positive electrode terminal 23 of one secondary battery 10 and the negative electrode terminal 24 of another secondary battery 10 located adjacent to the one secondary battery 10 is approximately 25 mm, the height a of the fixing nut 373 is 5 mm, the height c of the washer 374 is 1.6 mm, the diagonal distance b of the fixing nut 373 is 11.5 mm, the outer diameter d of the washer 374 is 12.5 mm, the thickness e of the inter-cell bus bar 53 is 1 mm, and the thickness f of the protection wall 34 is 1 mm. In this case, x = a + c = 5 + 1.6 = 6.6 y = 11.5 + (12.5 - 11.5) / 2 = 12 B = (x 2 + y 2 ) 1 / 2 = (6.6 2 + 12 2 ) 1 / 2 = 13.7 z = y - (B / 2 + f) = 12 - (13.7 / 2 + 1) = 4.15 The height H of the protection wall 34 > h = (x × z / y) + e = (6.6 × 4.15 / 12) + 1 = 3.28. Therefore, if the height H of the protection wall 34 > 3.28 mm, it is possible to more reliably prevent the dropped fixing nut 373 from contacting the second hexagonal bolt 37 and the third hexagonal bolt 37 simultaneously, and more reliably prevent the occurrence of the above short circuit.

[0081] For example, assume that the distance L in the Y-axis direction between, for example, the positive electrode terminal 23 of one secondary battery 10 and, for example, the negative electrode terminal 24 of another secondary battery 10 located adjacent to the one secondary battery 10 is approximately 17.5 mm, the height a of the fixing nut 373 is 3.2 mm, the height c of the washer 374 is 0.8 mm, the diagonal distance b of the fixing nut 373 is 8.1 mm, the outer diameter d of the washer 374 is 9 mm, the thickness e of the inter-cell bus bar 53 is 1 mm, and the thickness f of the protection wall 34 is 1 mm. In this case, x = a + c = 3.2 + 0.8 = 4 y = 8.1 + (9 - 8.1) / 2 = 8.55 B = (x 2 + y 2 ) 1 / 2 = (4 2 + 8.55 2 ) 1 / 2=9.44 z=y-(B / 2+f)=8.55-(9.44 / 2+1)=2.83 The height of the protective wall 34 H>h=(x×z / y)+e=(4×2.83 / 8.55)+1=2.32. Therefore, if the height of the protective wall 34 H>2.32mm, it is possible to more reliably prevent the fallen fixing nut 373 from simultaneously contacting the second hexagonal bolt 37 and the third hexagonal bolt 37, thereby more reliably preventing the occurrence of the short circuit described above.

[0082] As described above, the terminal structure 12 of Embodiment 1, which is disposed in a secondary battery 10 having an outer container 2 in which a power generation element 27 is housed, and a positive electrode terminal 23 and a negative electrode terminal 24 formed on the upper surface of the outer container 2, comprises a cap 3 made of resin material that is connected to the upper part of the outer container 2 and covers the upper part, and a busbar 4 disposed on the cap 3 and having one end 41 welded to the positive electrode terminal 23 (negative electrode terminal 24), a connecting piece 42 integrally connected to the one end 41 and rising from the one end 41, and the other end 43 integrally connected to the connecting piece 42, and the cap 3 has an opening 33 that exposes the positive electrode terminal 23 (negative electrode terminal 24) upward, and the busbar 4 The busbar 4 comprises a terminal surface 306 on which one end 41 is placed, a fastener placement surface 304 on which the other end 43 of the busbar 4 is placed with a step between it and the terminal surface 306, a recess 305 formed in the fastener placement surface 304 to accommodate a fastener (e.g., a hexagonal bolt 37) so that it does not rotate freely, a hexagonal bolt 37 which is a fastener housed in the recess 305 and connected to the positive terminal 23 (negative terminal 24) by the busbar 4, and a protective wall 34 which is erected laterally in the Y-axis direction of the hexagonal bolt 37 housed in the recess 305 and the busbar 4 placed on the fastener placement surface 304 and extends along the first direction (X-axis direction) from one end 41 to the other end 43 of the busbar 4. Therefore, when multiple secondary batteries 10 are arranged in a row and connected by inter-cell busbars 53 to form a module 1, the protective wall 34 can separate a hexagonal bolt 37 connected to, for example, the positive terminal 23 of one secondary battery 10 from a hexagonal bolt 37 connected to, for example, the negative terminal 24 of another secondary battery 10 located next to the first secondary battery 10. As a result, even if a worker accidentally drops a fixing nut 373 that has been removed from a hexagonal bolt 37 on module 1, it is possible to prevent a short circuit from occurring between adjacent secondary batteries 10 due to the dropped fixing nut 373.

[0083] For example, when module 1 is formed by multiple secondary batteries 10, in the example shown in Figure 20, the secondary batteries 10 are not arranged in parallel in the X-axis direction, but the secondary batteries 10 may be arranged in parallel in the X-axis direction as well. In this case, for example, the terminal structure 12A of Embodiment 2 shown in Figure 5 may be arranged on the secondary batteries 10. On the upper surface of the base 30 of the cap 3A of the terminal structure 12A, for example, on the positive terminal 23 side and the negative terminal 24 side, in addition to two protective walls 34 extending in the longitudinal direction (X-axis direction) of the base 30, there are two second protective walls 342 extending in the short direction (Y-axis direction) of the base 30. Therefore, even if a worker accidentally drops a fixing nut 373 that has been removed from a hexagonal bolt 37 on module 1, the second protective walls 342 can prevent a short circuit from occurring between adjacent secondary batteries 10 in the X-axis direction due to the dropped fixing nut 373. In other words, the hexagonal bolt 37 and fixing nut 373 connected to, for example, the positive terminal 23 of one secondary battery 10 can be separated from the hexagonal bolt 37 and fixing nut 373 connected to, for example, the negative terminal 24 of another secondary battery 10 located next to the first secondary battery 10 in the X-axis direction by the second protective wall 342 shown in Figure 5. This prevents a fallen fixing nut 373 from simultaneously coming into contact with the two adjacent hexagonal bolts 37 in the X-axis direction.

[0084] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0085] 1: Module 10: Secondary battery 12: Terminal structure of Embodiment 1 2: Outer container 20: Container body 21: Lid 23: Positive terminal 24: Negative terminal 27: Power generation element 3: Cap 30: Base 304: Fastener placement surface 305: Recess 306: Terminal surface 33: Opening 330: Frame 34: Protection wall 37: Hex bolt 373: Fixing nut 374: Washer 38: Hex nut 386: Fixing bolt 4: Bus bar 41: One end 42: Connecting piece 43: Other end 12A: Terminal structure of embodiment 2 342: Second protective wall 12B: Terminal structure of Embodiment 3 344: Notch 12C: Terminal structure of embodiment 4 347: Snap fit 10A: Another example of a secondary battery 23a: Positive terminal which is a bolt terminal 24a: Negative terminal which is a bolt terminal 51: Resin case 516: Partition wall 517: Storage room 53: Inter-cell busbar

Claims

1. It is installed in a secondary battery comprising an outer casing containing a power generation element, and terminals formed on the upper surface of the outer casing. A cap made of resin material, connected to the top of the outer container and covering the top, A busbar is provided, having one end disposed on the cap and welded to the terminal, a connecting piece integrally connected to the one end and rising from the one end, and the other end integrally connected to the connecting piece. The cap comprises an opening that exposes the terminal upward, a terminal surface on which one end of the busbar is placed, a hexagonal bolt placement surface on which the other end of the busbar is placed, a recess formed on the hexagonal bolt placement surface to accommodate the hexagonal bolt so as not to rotate freely, the hexagonal bolt housed in the recess and connected to the terminal by the busbar, and a protective wall erected to the side of the hexagonal bolt housed in the recess and the busbar placed on the hexagonal bolt placement surface, extending along a first direction from one end to the other end of the busbar. It comprises a fixing nut having a washer, which is screwed onto the hexagonal bolt and sandwiches the inter-cell busbar together with the hexagonal bolt, When multiple secondary batteries are arranged in a row and connected by inter-cell busbars to form a module, the protective wall separates the hexagonal bolt connected to the terminal of one secondary battery from the hexagonal bolt connected to the terminal of another secondary battery located next to that one secondary battery. If the distance between the terminals of one secondary battery and the terminals of another secondary battery located next to that one secondary battery is less than the maximum dimensions of the washer and the fixing nut, the height of the protective wall shall be greater than the fixing nut. If the distance between the terminals of one secondary battery and the terminals of another secondary battery located next to the one secondary battery is greater than or equal to the maximum dimensions of the washer and the fixing nut, then the height of the protective wall is a height H that satisfies the following formula (1), provided that the intersection of a straight line including the line segment indicating the lower end face of the washer and a straight line including the line segment indicating the upper end face of the intercellular busbar is point O, the base of a right triangle with the distance in the first direction from point O to the fixing nut as its base, the height being the sum of the height of the fixing nut and the height of the washer as its height, and point O as one of its vertices, and the height of the protective wall is a height H that satisfies the following formula (1). x = a + c y=b+(d-b) / 2 B=(x 2 + y 2 ) 1 / 2 z=y'-(B / 2+f) Height of protective wall H > (x × z / y') + e ... (1) a: Height of the fixing nut c: Washer height b: Diagonal distance of the fixing nuts d: Washer outer diameter B: Maximum dimensions of washers and fixing nuts f: Thickness of the protective wall e: Thickness of inter-cell busbars y': Distance in the Y-axis direction from point O to the adjacent fixing nut on the -Y side. O: The intersection of a straight line containing the line segment indicating the lower end face of the washer attached to the fallen fixing nut and a straight line containing the line segment indicating the upper end face of the inter-cell busbar.

2. The terminal structure according to claim 1, wherein the cap comprises the hexagonal bolt housed in the recess of the busbar and a second protective wall erected on the side of the busbar placed on the hexagonal bolt arrangement surface, and extending along a second direction perpendicular to the first direction.

3. The terminal structure according to claim 1, wherein a notch having a shape that is recessed in the thickness direction of the protective wall is formed along the extending direction of the protective wall.

4. The terminal structure according to claim 1, wherein the cap is a snap fit that presses one end of the busbar toward the terminal surface.

5. The terminal of the secondary battery is a columnar bolt terminal, The terminal structure according to claim 1, wherein the bolt terminal protrudes upward from the opening of the cap.

Images