JP5585524B2 - Assembled battery and manufacturing method of assembled battery - Google Patents

Description

  The present invention relates to an assembled battery formed by combining a plurality of batteries and a method for manufacturing the assembled battery. More specifically, the present invention relates to an assembled battery having a structure for restraining each battery and a method for manufacturing the assembled battery.

  In recent years, non-aqueous electrolyte secondary batteries such as lithium ion batteries have attracted attention as power sources not only for electronic devices such as portable PCs and mobile phones, but also for hybrid vehicles and electric vehicles. In such a secondary battery, the power generation element is housed in a metal case, and an insulating film is attached to the inside of the case to insulate the case from the power generation element.

  As the shape of the secondary battery case, various shapes such as a cylindrical shape and a rectangular shape have been put into practical use. Among these, the rectangular rectangular case has a higher space efficiency than other cases, and is widely used to meet the demand for miniaturization.

  The power generation element has a configuration in which a positive electrode and a negative electrode are stacked or wound via a separator, and a space between the elements is filled with an electrolytic solution. In the power generation element of the secondary battery, for example, the distance between the electrodes is likely to fluctuate due to expansion of the positive electrode during initial charging or vibration in the operating environment. When the distance between the electrodes fluctuates, bubbles and the like are likely to enter the electrolytic solution, which tends to deteriorate the battery performance.

  As a technique for keeping the gap between the electrodes of the power generation element constant, there is a technique disclosed in Patent Document 1, for example. In the assembled battery of Patent Document 1, a plurality of prismatic cells are arranged so that the flat surfaces are opposed to each other, and the periphery of the prismatic cells is collectively restrained by a restraining plate and a beam member. In addition, a spacer functioning as a heat sink is incorporated between adjacent rectangular cells.

JP 2008-108457 A

  However, the conventional technique described above has the following problems. That is, in the case of an assembled battery in which a plurality of prismatic cells are arranged in a row, the surface pressure applied to the battery case varies before and after charging and discharging at a high rate. Specifically, of the regions in the flat surface of the battery case, when the region overlapping with the power generation elements in the flat surface of the battery case as seen from the direction in which the cells are arranged is defined as the power generation region, In the central part, the surface pressure tends to increase. On the other hand, the surface pressure tends to decrease at the end in the power generation region. This variation in surface pressure is a factor that degrades battery performance. For example, when the surface pressure at the end portion is lower than that at the central portion, the electrolytic solution in the power generation element easily moves from the central portion to the end portion, and as a result, the electrolytic solution leaks out of the power generation element.

  The spacer as disclosed in Patent Document 1 is effective in terms of suppressing the expansion amount of the single cell unit. However, since the above-mentioned spacer uniformly loads the entire flat surface, it is difficult to cope with a partial increase in surface pressure within the flat surface. For this reason, deterioration of battery performance may not be suppressed.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is to provide an assembled battery and a method of manufacturing the assembled battery that reliably suppress deterioration of battery performance after charging and discharging at a high rate.

An assembled battery made for the purpose of solving this problem includes a power generation element, a rectangular case that accommodates the power generation element, a positive current collector terminal that is joined to one end of the power generation element, and the other of the power generation elements. A plurality of secondary batteries having a negative electrode current collector terminal joined to an end of the battery, and the adjacent secondary batteries are arranged side by side with the flat surfaces of the square cases facing each other, A plurality of the secondary batteries arranged in a row are restrained together, a restraining member that loads each secondary battery in the row direction of the secondary batteries, and one flat surface of the square case of the secondary battery Is in the power generation region that is in contact with the first surface, and overlaps with the power generation element in the region in the first surface when viewed from the row direction, and on the positive current collector terminal side of the power generation region The first region, which is the region including the end of the power generation region and not including the central portion of the power generation region, is loaded. One spacer is in contact with the first surface, and the region within the first surface is within the power generation region as viewed from the row direction, and the end of the power generation region on the negative current collector terminal side is And a second spacer that loads a second region that does not include a central portion of the power generation region, and the first spacer and the second spacer are used for a charge / discharge test performed on the secondary battery. It is characterized in that the range in which the surface pressure is reduced is loaded and the range in which the surface pressure is not reduced in the test is not loaded .

  The assembled battery of the present invention is a battery in which a plurality of secondary batteries (unit cells) having a square case are arranged in a row, and a restraining member collectively restrains these secondary batteries and loads them in the row direction. Yes. Two spacers (first spacer and second spacer) are in contact with one flat surface of the secondary battery constituting the assembled battery, and the spacer presses the flat surface in accordance with the load of the restraining member. . Specifically, the first spacer presses the first region including the end on the positive electrode current collecting terminal side in the power generation region in the flat surface, and the second spacer includes the negative electrode in the power generation region in the flat surface. The second region including the end portion on the current collecting terminal side is pressed.

  That is, in the assembled battery of the present invention, the first spacer and the second spacer sandwiched between the secondary batteries are regions including the end portion of the power generation region in the flat surface of the square case and include the central portion. Load no area. Thereby, the area | region which loads a flat surface and the area | region which does not load are provided. Furthermore, since the first spacer and the second spacer are separate, the position of each spacer can be adjusted, and the spacer can be appropriately arranged for each secondary battery. Therefore, even if there is a dimensional error or an assembly error for each secondary battery, the position of the spacer can be finely adjusted. As a result, it can be expected that the surface pressure in the flat surface of the square case approaches uniformly, and the deterioration of the battery performance is surely suppressed.

  The assembled battery of the present invention is located between the adjacent secondary batteries, and one surface is in contact with the first spacer and the second spacer that load the flat surface of one secondary battery, and the other It is preferable to provide an interposition member whose surface is in contact with the flat surface of the other secondary battery. With this configuration, only the flat surface of one secondary battery is in contact with the first spacer and the second spacer. Therefore, adverse effects on the surface pressure of the other secondary battery can be avoided with respect to the load caused by these spacers.

  The first spacer and the second spacer may be formed by overlapping a plurality of flat plate members in the arrangement direction. According to this configuration, it is possible to adjust the thickness of the spacers in the arrangement direction, that is, to adjust the size of the air gap and the size of the surface pressure.

  The first spacer and the second spacer may be formed by overlapping a plurality of rectangular parallelepiped block members in a direction perpendicular to the arrangement direction. According to this configuration, it is possible to adjust the range of the region loaded by the spacer.

The assembled battery manufacturing method of the present invention includes a power generation element, a rectangular case that houses the power generation element, a positive current collector terminal that is joined to one end of the power generation element, and the other of the power generation elements. A method of manufacturing an assembled battery, comprising a plurality of secondary batteries each having a negative electrode current collector terminal joined to an end, and the adjacent secondary batteries arranged in a row with the flat surfaces of the square cases facing each other. The acquisition step of performing a charge / discharge test on each secondary battery constituting the assembled battery and acquiring the surface pressure before the charge / discharge test and the surface pressure after the charge / discharge test, and acquiring at the acquisition step For each secondary battery based on the measured surface pressure, a specifying step for specifying a place where the surface pressure decreases in the flat surface of the square case, and after the specifying step, one flat surface of the secondary battery The space for loading the location specified in the specific step is Place the sub, in places that are not identified in the identifying step is characterized in that it comprises an arrangement step that does not place the spacer.

  That is, in the method for manufacturing an assembled battery according to the present invention, the surface pressure before and after the charge / discharge test is obtained, and the surface pressure in the flat surface of the square case decreases due to the change in the surface pressure before and after the test. Is identified. As the charge / discharge test, it is only necessary to charge or discharge a large current. For example, the test is performed at a rate of 20 C or more. And a spacer is arrange | positioned in the place where the surface pressure falls. According to this configuration, since the spacer is arranged after confirming the place where the surface pressure is reduced, the place can be appropriately loaded. In addition, even if there are dimensional errors and assembly errors for the secondary battery, the location where the surface pressure is reduced is specified for each secondary battery, so that the secondary battery can be appropriately loaded. As a result, it can be expected that the surface pressure in the flat surface of the square case approaches uniformly, and the deterioration of the battery performance is surely suppressed.

  Further, in the arranging step, between the adjacent secondary batteries, one surface is in contact with the spacer that loads a flat surface of one secondary battery, and the other surface is a flat surface of the other secondary battery. It is good to arrange the interposition member which touches. By arranging an interposition member between two adjacent secondary batteries in which a spacer is arranged, only the flat surface of one secondary battery is in contact with the spacer. Therefore, an adverse effect on the surface pressure of the other secondary battery can be avoided with respect to the load by the spacer.

  In the arranging step, the thickness of the spacers in the arrangement direction of the secondary batteries is determined based on the amount of change between the pre-test surface pressure and the post-test surface pressure acquired in the surface pressure acquisition step. It is good to adjust. According to this configuration, it is possible to adjust the thickness of the spacers in the arrangement direction, that is, to adjust the size of the air gap and the size of the surface pressure.

  In the arranging step, the size of the spacer in the direction orthogonal to the arrangement direction of the secondary batteries may be adjusted based on the range of the place specified in the specifying step. According to this configuration, it is possible to adjust the range of the region loaded by the spacer.

  ADVANTAGE OF THE INVENTION According to this invention, the assembled battery and the manufacturing method of an assembled battery which suppress reliably deterioration of the battery performance after charging / discharging at a high rate are implement | achieved.

It is a perspective perspective view which shows the structure of the lithium ion single battery concerning embodiment. It is a figure which shows the structure of the lithium ion assembled battery formed by combining multiple lithium ion single batteries shown in FIG. It is a figure which shows the arrangement | positioning relationship of the spacer located in one flat surface of a lithium ion single battery. It is a figure which shows the arrangement | positioning relationship of the cooling plate located in the other flat surface of a lithium ion single battery. It is a flowchart which shows the manufacture procedure of the lithium ion assembled battery shown in FIG. It is a graph which shows the surface pressure distribution at the time of a high rate test. It is a figure which shows the example of the spacer arranged in the row direction. It is a figure which shows the example of the spacer juxtaposed in the width direction.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying an assembled battery according to the present invention will be described below in detail with reference to the accompanying drawings. In the following embodiment, the present invention is applied to a lithium ion assembled battery mounted on a hybrid vehicle.

[Configuration of lithium-ion battery]
First, a lithium ion unit cell 100 constituting a lithium ion assembled battery will be described with reference to FIG.

As shown in FIG. 1, the lithium ion unit cell 100 according to the present embodiment includes a power generation element 60 and a sealed outer casing 50 that houses the power generation element 60 and forms an outer shell of the lithium ion unit cell 100. This is a prismatic secondary battery. FIG. 1 shows a state in which the exterior portion 50 is seen through. In the following description, for convenience of description, the width direction "width direction" (X direction in FIG. 1) of the exterior unit 50, the height direction of the exterior portion 50 (Y direction in FIG. 1) the "height direction" The depth direction of the exterior portion 50 (the Z direction in FIG. 1) is defined as the “row placement direction”.

  The exterior portion 50 includes a battery case 10 serving as a container and a sealing lid 20 that seals an opening of the battery case 10. The battery case 10 is made of a metal material such as aluminum, an aluminum alloy, a plated steel plate, or a stainless steel plate. The sealing lid 20 is made of a metal material such as aluminum, a plated steel plate, or a stainless steel plate. The metal material used for the battery case 10 and the sealing lid 20 may be any material that can be easily molded and has rigidity. An insulating film (not shown) is attached to the entire inner surface of the exterior portion 50.

  The battery case 10 is a bottomed rectangular box, that is, a rectangular parallelepiped having an upper surface opened. The battery case 10 houses the power generation element 60 and seals the power generation element 60 by closing the opening with a rectangular plate-shaped sealing lid 20. Specifically, in the exterior part 50, the battery case 10 and the sealing lid 20 are integrated by laser welding.

  A positive electrode collector terminal 31 and a negative electrode collector terminal 32 are attached to the sealing lid 20 so as to penetrate the sealing lid 20 and protrude from the sealing lid 20 toward the outside of the exterior portion 50. An insulating member 33 made of resin is interposed at a position where the positive current collecting terminal 31 is attached to the sealing lid 20 to insulate the positive current collecting terminal 31 from the sealing lid 20. Similarly, an insulating member 34 made of resin is interposed at a location where the negative electrode current collecting terminal 32 is attached to the sealing lid 20 to insulate the negative electrode current collecting terminal 32 from the sealing lid 20. A rectangular plate-shaped safety valve 23 is also welded to the sealing lid 20. The safety valve 23 seals a liquid injection hole that penetrates the sealing lid 20, and an electrolytic solution is injected from the liquid injection hole.

The power generation element 60 is obtained by winding a belt-like positive electrode plate 61 and a belt-like negative electrode plate 62 with a separator made of polyethylene interposed therebetween to make it flat. The positive electrode plate 61 carries a positive electrode active material layer (not shown) on both surfaces of an aluminum foil. The positive electrode active material layer includes, for example, lithium nickel oxide (LiNiO ₂ ) as a positive electrode active material, acetylene black as a conductive agent, and polytetrafluoroethylene (PTFE) and carboxymethyl cellulose (CMC) as a binder. The negative electrode plate 62 carries a negative electrode active material layer (not shown) on both sides of the copper foil. This negative electrode active material layer contains, for example, graphite and a binder. The electrolyte solution (not shown) is lithium hexafluorophosphate as a solute in a mixed organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are adjusted to a volume ratio of EC: EMC = 3: 7. (LiPF ₆ ) is added, and the organic electrolyte has a lithium ion concentration of 1 mol / l. The materials used for the positive electrode plate 61, the positive electrode active material layer, the negative electrode plate 62, the negative electrode active material layer, and the electrolytic solution are merely examples, and materials generally used for lithium ion batteries may be appropriately selected.

  The positive electrode plate 61 is joined to a plate-like positive electrode current collecting terminal 31 bent in a crank shape, and the negative electrode plate 62 is joined to a plate-like negative electrode current collecting terminal 32 also bent in a crank shape. Specifically, the positive electrode current collecting terminal 31 is joined to the positive electrode plate 61 exposed at one end in the width direction of the power generation element 60. On the other hand, the negative electrode current collecting terminal 32 is joined to the negative electrode plate 62 exposed at the other end in the width direction of the power generation element 60. In the present embodiment, the center position in the width direction in the power generation element 60 is referred to as “center position 60P”.

[Configuration of lithium-ion battery pack]
Next, a lithium ion assembled battery 200 formed by combining a plurality of lithium ion single cells 100 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a view of the lithium ion assembled battery 200 as viewed from the height direction (Y direction in FIG. 1).

  The lithium ion assembled battery 200 includes a plurality of lithium ion single batteries 100, a pair of end plates 71 and 72 positioned at both ends of the arrangement direction of lithium ion assembled batteries (Z direction in FIG. 2), and lithium ion single batteries. Spacers 81 and 82 in contact with one flat surface of the battery 100 and a cooling plate 83 sandwiched between adjacent lithium ion cells 100 and 100 are included.

  As shown in FIG. 2, the lithium ion unit cells 100 are arranged side by side in the row direction with the flat surfaces facing each other. Here, it arrange | positions so that the positive electrode current collection terminal 31 of one lithium ion single cell 100 and the negative electrode current collection terminal 32 of the other lithium ion single cell 100 may face each other. Then, the positive electrode current collecting terminal 31 of one lithium ion unit cell 100 and the negative electrode current collecting terminal 32 of the other lithium ion unit cell 100 are electrically connected by a bus bar 91. Thereby, all the lithium ion single batteries 100 which comprise the lithium ion assembled battery 200 are connected in series. In addition, the number of the lithium ion single cells 100 is appropriately determined depending on the required output. Moreover, you may combine the lithium ion cell 100 electrically connected in parallel.

  A restraining band 73 is attached to the end plates 71 and 72 so as to extend in the row direction and is disposed along the side surface of each lithium ion unit cell 100. The restraint band 73 applies a restraining force F to the end plates 71 and 72 by being fixed to the end plates 71 and 72 while being fastened. The restraining force F is a force that is generated in a direction in which the end plates 71 and 72 approach each other, and is a force that restrains the lithium ion cells 100 sandwiched between the end plates 71 and 72 in the row direction. The lithium ion cells 100 sandwiched between the end plates 71 and 72 are loaded in the row direction by the restraining member including the end plates 71 and 72 and the restraining band 73.

  The spacers 81 and 82 are separate bodies and are in close contact with one flat surface of the lithium ion unit cell 100. The spacers 81 and 82 can be made of a metal having high thermal conductivity such as aluminum or a light and hard synthetic resin such as polypropylene. The spacers 81 and 82 receive the restraining force F from the restraining band 73 and load the flat surface of the lithium ion unit cell 100 that is in close contact. In the battery case 10 of the lithium ion unit cell 100 that is in close contact with the spacers 81 and 82, the close portions with the spacers 81 and 82 are recessed inward due to the load described above. The recess of the battery case 10 presses the power generation element 60 in the battery case 10 and suppresses rattling of the power generation element 60 in the battery case 10.

  The spacer 81 is in close contact with the region on the positive electrode current collecting terminal 31 side in the width direction of the flat surface of the lithium ion unit cell 100. On the other hand, the spacer 82 is in close contact with the region on the negative electrode current collector terminal 32 side in the width direction of the flat surface of the lithium ion unit cell 100.

  Here, specific positions of the spacers 81 and 82 in the flat surface of the lithium ion unit cell 100 will be described. FIG. 3 shows the positions where the spacers 81 and 82 are in close contact with each other by hatching. A two-dot chain line frame in FIG. 3 is a region (hereinafter referred to as “power generation region A”) in the flat surface of the lithium ion unit cell 100 and located at the same position as the power generation area of the power generation elements 60 when viewed from the row direction. Is shown. The power generation area of the power generation element 60 here means an area where at least the positive electrode plate 61 and the negative electrode plate 62 overlap. Furthermore, the power generation region A includes a positive electrode side end region A1 located at the end portion on the positive electrode current collecting terminal 31 side in the width direction and a negative electrode side end region A2 located on the end portion on the negative electrode current collector terminal 32 side in the width direction. And a center region A3 that is located between the positive electrode side end region A1 and the negative electrode side end region A2 and includes the center position 60P.

  The width of the spacer 81 is substantially equal to the width W1 of the positive electrode side end region A1, and the spacer 81 is disposed at a position overlapping the positive electrode side end region A1. On the other hand, the width of the spacer 82 is substantially equal to the width W2 of the negative electrode side end region A2, and the spacer 82 is disposed at a position overlapping the negative electrode side end region A2. In addition to the width direction, the height direction is also aligned. With this configuration, in the lithium ion battery pack 200, when the restraint band 73 is assembled, the spacers 81 and 82 cause a portion of the flat surface of the lithium ion cell 100, specifically, the positive electrode side end region A1 and the negative electrode side end. Only the partial area A2 is loaded. Therefore, the surface pressure of the positive electrode side end region A1 and the negative electrode side end region A2 of the flat surface of the lithium ion cell 100 increases.

  The cooling plate 83 is a flat member and is inserted between adjacent lithium ion cells 100, 100. Specifically, one surface is in contact with the flat surface of one lithium ion unit cell 100 and the other surface is in contact with the spacer 81 and the spacer 82 that load the flat surface of the other lithium ion unit cell 100.

  As shown in FIG. 4, the cooling plate 83 has a width and height substantially equal to the power generation region A, and is disposed at a position overlapping the power generation region A when viewed from the row direction. That is, the area of the flat surface of the cooling plate 83 is substantially equal to the area of the power generation region A. The surface opposite to the surface in contact with the spacers 81 and 82 is in contact with the flat surface of another lithium ion cell 100 facing the lithium ion cell 100 loaded on the spacers 81 and 82. For other lithium ion cells 100, since the cooling plate 83 is interposed between the spacers 81 and 82, the load by the spacers 81 and 82 is dispersed in the width direction or the height direction. In other words, the other lithium ion cells 100 in contact with the cooling plate 83 are loaded substantially uniformly in the width direction by the cooling plate 83.

  A metal having high thermal conductivity such as aluminum can be applied to the cooling plate 83. Heat generated from the power generation element 60 of the lithium ion unit cell 100 in contact with the cooling plate 83 is transmitted to the cooling plate 83 and released to the outside of the battery case 10.

  Further, a gap 85 surrounded by the spacer 81, the cooling plate 83, the spacer 82, and the flat surface of the other lithium ion unit cell 100 is formed between the adjacent lithium ion unit cells 100, 100. By introducing a refrigerant flow (for example, air flow or water flow) into the gap 85, the cooling effect is enhanced.

[Method for producing lithium-ion battery pack]
Next, a method for manufacturing the above-described lithium ion assembled battery 200 will be described by focusing on the procedure for attaching the spacers 81 and 82. FIG. 5 is a flowchart showing a manufacturing procedure of the lithium ion assembled battery 200.

  In the manufacturing procedure of the lithium ion assembled battery 200, first, the lithium ion single battery 100 is manufactured (S01). The manufactured lithium ion unit cell 100 is subjected to various inspections of battery performance, and defective products are removed.

  For the lithium ion unit cell 100 that has become a non-defective product, the surface pressure applied to the flat surface of the lithium ion unit cell 100 is measured (S02). In S02, the surface pressure in the entire width direction of the flat surface is measured. For the surface pressure measurement, a general surface pressure sensor may be used. Further, in the measurement of S02, when the variation in the surface pressure in the width direction of the flat surface exceeds the allowable range, it is removed as a defective product. In addition, you may perform the measurement of S02 before performing the various test | inspection with respect to the lithium ion single battery 100 after manufacture.

  Next, a charge / discharge test at a high rate is performed (S03). Then, the surface pressure applied to the flat surface of the lithium ion cell 100 is measured again after the charge / discharge test (S04). In S04, the same part as S02 is measured by the same method. And the measurement result of S02 and the measurement result of S04 are compared, and the range where the surface pressure fell in the width direction of a flat surface is specified (S05).

  When the lithium ion unit cell 100 is repeatedly charged and discharged at a high rate, the amount of change in surface pressure tends to increase at the end of the power generation element 60. For example, FIG. 6 shows the change rate of the surface pressure after discharging at 36 C (rate) for 5 seconds. In FIG. 6, the vertical axis represents the rate of change in surface pressure between S02 and S04, and the horizontal axis represents the position in the width direction of the power generation region A of the battery case 10 (the end on the positive electrode current collector terminal side is 0). And the end on the negative electrode current collector terminal side is 100).

  As shown in FIG. 6, in the lithium ion battery 100 of this embodiment, after the high-rate test in S03, in the width direction of the power generation region A, the central portion (the portion of 21 to 82 on the horizontal axis in FIG. 6) is the surface. It can be seen that the pressure increases and the surface pressure decreases in the region on the end side (portions 0 to 20 and 83 to 100 on the horizontal axis in FIG. 6). Thus, by measuring the surface pressure before and after the high rate test, the range in which the surface pressure has decreased can be identified.

  In the present embodiment, in the range where the surface pressure is reduced, that is, the range where the surface pressure change rate is 100% or less, the range on the positive electrode current collecting terminal 31 side from the center position 60P (0 to 0 on the horizontal axis in FIG. 6). (Corresponding to the portion 20) is defined as “restraint range R1”, and the range on the negative electrode current collector terminal 32 side (corresponding to the portion 83 to 100 on the horizontal axis in FIG. 6) is defined as “restraint range R2”. The restraint range R1 is equivalent to the width of the positive electrode side end region A1 in FIG. Further, the constraint range R2 is equivalent to the width of the negative electrode side end region A2 in FIG.

  Next, a spacer 81 having the same width as the restriction range R1 and a spacer 82 having the same width as the restriction range R2 are prepared, the spacer 81 is arranged at the position of the restriction range R1, and the spacer 82 is arranged at the position of the restriction range R2. (S06). Then, a cooling plate 83 is sandwiched between the lithium ion cells 100, 100, the restraint band 73 is fastened to the end plates 71, 72, and bus bars 91, 92 are assembled to each lithium ion cell 100 to complete the lithium ion assembled battery 200. (S07). After S07, the manufactured lithium ion assembled battery 200 is subjected to various tests of battery performance, defective products are removed, and non-defective products are shipped.

[Application example of spacer]
[First application example]
Next, application examples of the spacers 81 and 82 will be described. The spacer of the first application example is composed of a plurality of blocks. This point is different from the spacers 81 and 82 of the embodiment constituted by one block, that is, a single unit.

  FIG. 7 shows the configuration of the spacer 86 of the first application example. The spacer 86 is formed by arranging a plurality of flat plates 861 in the arrangement direction. Each plate 861 has the same size in the width direction and the height direction. The height of the plates 861 in the row direction may be the same or different.

  According to the spacer 86 of the first application example, the load applied to the flat surface of the lithium ion unit cell 100 can be adjusted by adjusting the number of the plates 861, that is, by adjusting the height of the spacers 86 in the row direction. Can be adjusted. For example, if the number of the plates 861 is reduced and the height of the spacers 86 in the row direction is lowered, the load applied by the spacers 86 becomes weaker. On the other hand, if the number of plates 861 is increased and the height of the spacers 86 in the row direction is increased, the load applied by the spacers 86 becomes stronger.

  The height of the spacer 86 is determined according to the change rate of the surface pressure. For example, if the rate of change is large, the height of the spacer 86 is increased, and the surface pressure of the lowered portion is increased. On the other hand, if the change rate is small, the height of the spacer 86 is lowered and the surface pressure is finely adjusted.

[Second application example]
As in the first application example, the spacer of the second application example is composed of a plurality of blocks. However, in the second application example, a plurality of blocks are juxtaposed in the width direction. This is different from the spacer 86 of the first application example in which a plurality of plates are stacked in the row direction.

  FIG. 8 shows the configuration of the spacer 87 of the second application example. The spacer 87 is formed by juxtaposing a plurality of rectangular blocks 871 in the width direction. The sizes of the blocks 871 in the row direction and the height direction are the same. The size in the width direction of each block 871 may be the same or different.

  According to the spacer 87 of the second application example, by adjusting the number of blocks 871, that is, by making it possible to adjust the size of the spacer 87 in the width direction, the region 87 in which the surface pressure of the lithium ion unit cell 100 decreases is reduced. Even if there is a variation in the width, the variation can be dealt with. For example, if the constraint range R2 is wide, the width of the spacer 87 can be increased by increasing the number of blocks 871. On the other hand, if the constraint range R2 is narrow, the width of the spacer 87 can be reduced by reducing the number of blocks 871.

  In the second application example, the plurality of blocks 871 are arranged in the width direction, but may be arranged in the height direction. A plurality of blocks 871 may be arranged in both the width direction and the height direction. Further, the first application example and the second application example may be combined, and a plurality of blocks or plates may be arranged in three directions of the arrangement direction, the width direction, and the height direction.

  As described above in detail, in the lithium ion assembled battery 200 of the present invention, the spacers 81 and 82 in contact with the flat surface of the lithium ion unit cell 100 are regions including the end portion of the power generation region A and not including the central portion. The areas A1 and A2 are loaded. As a result, areas A1 and A2 that load the flat surface and areas A3 that do not load are provided, and the surface pressure of the areas A1 and A2 that are loaded, that is, the area where the surface pressure is reduced due to charge / discharge at a high rate, is increased. be able to. Furthermore, since the spacer 81 and the spacer 82 are separate bodies, the positions of the spacers 81 and 82 can be adjusted individually, and the spacers 81 and 82 can be appropriately arranged for each lithium ion cell 100. Therefore, the position of the spacer can be finely adjusted even if there is a dimensional error or an assembly error for each lithium ion cell 100. As a result, it can be expected that the surface pressure in the flat surface of the lithium ion unit cell 100 approaches uniformly and the deterioration of the battery performance is surely suppressed.

  Moreover, in the manufacturing method of the lithium ion assembled battery 200 of the present invention, the surface pressure before and after performing the charge / discharge test at the high rate is obtained, and the change rate of the surface pressure before and after the test is used to determine the individual The place where the surface pressure in the flat surface decreases is specified. Then, the spacers 81 and 82 are respectively arranged at the places where the surface pressure decreases (in the embodiment, the restriction range R1 and the restriction range R2). According to this configuration, the place where the surface pressure is reduced is confirmed and the spacers 81 and 82 are arranged, so that the place can be appropriately loaded. In particular, even if there is a dimensional error or assembly error for the lithium ion unit cell 100, the location where the surface pressure is reduced is specified for each lithium ion unit cell 100. Can be loaded. Therefore, the surface pressure in the flat surface of the battery case 10 approaches uniformly and the surface pressure becomes uniform, so that partial expansion or contraction of the power generation element 60 is suppressed. As a result, it can be expected that the deterioration of the battery performance is surely suppressed.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the lithium ion battery is not limited to being mounted on a vehicle, but may be used for home appliances and personal computers. The battery is not limited to a lithium ion battery. That is, the present invention can be applied to a secondary battery such as a nickel metal hydride battery or a nickel cadmium battery.

  The spacer 81 only needs to be in contact with at least a region including the end of the power generation region A on the positive current collector terminal 31 side, and its width does not exactly match the width W1 of the positive end region A1. May be. The spacer 82 only needs to be in contact with at least the region including the end of the power generation region A on the negative electrode current collector terminal 32 side, and the width thereof may not exactly match the width W2 of the positive electrode end region A2. Good. For example, the spacers 81 and 82 may also load a region outside the power generation region A.

  The cooling plate 83 may be any width and height that can contact the spacers 81 and 82, and the width and height may be longer than the width and height of the power generation region A. That is, the area of the flat surface of the cooling plate 83 is equal to or larger than the area of the power generation region A.

  Further, the cooling plate 83 does not have to be arranged if there is no other lithium ion unit cell 100 facing the flat surface on the flat surface side that is loaded by the spacers 81 and 82 of the lithium ion unit cell 100 ( For example, see the end plate 72 side portion of the assembled battery 200 shown in FIG. 2). Further, for example, when only two lithium ion cells 100 are arranged in a row, the cooling plate 83 is not necessary if the spacers 81 and 82 are arranged on the flat surface on the outer side of both lithium ion cells.

  In the embodiment, charging and discharging are performed for 36C5 seconds in the high-rate test of S03, but the present invention is not limited to this. The high-rate test is not particularly limited as long as it can charge and discharge a large current. For example, in the lithium ion unit cell 100 of this embodiment, charging or discharging may be performed at a rate of 20 C or higher.

10 Battery case (square case)
31 Positive current collector terminal 32 Negative current collector terminal 60 Power generation element 61 Positive electrode plate 62 Negative electrode plate 73 Restraint band (restraint member)
81 Spacer (first spacer)
82 Spacer (second spacer)
83 Cooling plate (intervening member)
100 Lithium ion cell (secondary battery)
200 Lithium ion battery pack (battery pack)
A Power generation region A1 Positive electrode side end region (first region)
A2 Negative electrode side end region (second region)

Claims (8)

Power generation elements;
A square case for housing the power generation element;
A positive current collector terminal joined to one end of the power generating element;
A negative current collector terminal joined to the other end of the power generation element;
A plurality of secondary batteries having
In the assembled battery in which the adjacent secondary batteries are arranged in a row with the flat surfaces of the square cases facing each other,
A constraining member that collectively restrains the plurality of secondary batteries arranged in a row, and loads each secondary battery in the direction in which the secondary batteries are arranged;
A power generation region that is in contact with a first surface that is one flat surface of the rectangular case of the secondary battery and that overlaps the power generation element when viewed from the row direction in the region in the first surface. A first spacer for loading a first region that includes an end of the power generation region on the side of the positive current collector terminal and does not include a central portion of the power generation region;
The power generation region is in contact with the first surface and is within the power generation region of the region within the first surface when viewed from the row direction, and includes an end of the power generation region on the negative current collector terminal side, A second spacer for loading the second region, which is a region not including the central portion of the region;
Equipped with a,
The first spacer and the second spacer are loaded in a range where the surface pressure is reduced in the charge / discharge test performed on the secondary battery, and are not loaded in the range where the surface pressure is not reduced in the test. A battery pack characterized by. The assembled battery according to claim 1,
Located between adjacent secondary batteries, one surface is in contact with the first spacer and the second spacer that load the flat surface of one secondary battery, and the other surface is the flat surface of the other secondary battery. An assembled battery comprising an interposition member in contact with the surface. In the assembled battery according to claim 1 or 2,
The assembled battery, wherein the first spacer and the second spacer are formed by overlapping a plurality of flat plate members in the row direction. In the assembled battery according to any one of claims 1 to 3,
A plurality of the first spacers and the second spacers are formed by stacking a plurality of rectangular parallelepiped block members in a direction orthogonal to the arrangement direction. Power generation elements;
A square case for housing the power generation element;
A positive current collector terminal joined to one end of the power generating element;
A negative current collector terminal joined to the other end of the power generation element;
A plurality of secondary batteries having
In the manufacturing method of an assembled battery in which the secondary batteries adjacent to each other are arranged with the flat surfaces of the square cases facing each other,
An acquisition step of performing a charge / discharge test on each secondary battery constituting the assembled battery and acquiring a surface pressure before the charge / discharge test and a surface pressure after the charge / discharge test;
Based on the surface pressure acquired in the acquisition step, for each secondary battery, a specifying step for specifying a place where the surface pressure decreases in the flat surface of the square case;
After the specifying step, on one flat surface of the secondary battery, a spacer that loads the place specified in the specifying step is arranged, and a spacer is not arranged in a place that is not specified in the specifying step. Steps,
A method for producing an assembled battery, comprising: In the manufacturing method of the assembled battery according to claim 5,
In the arrangement step, between the adjacent secondary batteries, one surface is in contact with the spacer that loads the flat surface of one secondary battery, and the other surface is in contact with the flat surface of the other secondary battery. A method for producing an assembled battery, comprising arranging members. In the manufacturing method of the assembled battery according to claim 5 or 6,
In the arranging step, the thickness of the spacers in the arrangement direction of the secondary batteries is adjusted based on the amount of change between the pre-test surface pressure and the post-test surface pressure acquired in the surface pressure acquisition step. A method for producing an assembled battery, comprising: In the manufacturing method of the assembled battery as described in any one of Claims 5-7,
In the arranging step, the size of the spacer in the direction orthogonal to the arrangement direction of the secondary batteries is adjusted based on the range of the location specified in the specifying step. Method.

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