Lead storage battery

Abstract

A lead storage battery comprising a positive electrode plate and a negative electrode plate, wherein: the positive electrode plate or the negative electrode plate includes a rectangular current collector and an active material loaded in the current collector; the current collector is an expanded grid in which cells constituting the current collector are each in a diamond shape; a frame body surrounding each of the cells includes a lower left bar positioned at the lower left, an upper left bar positioned at the upper left, a lower right bar positioned at the lower right, an upper right bar positioned at the upper right, a lower node that connects the lower end of the lower left bar and the lower end of the lower right bar, a left node that connects the upper end of the lower left bar and the lower end of the upper left bar, a right node that connects the upper end of the lower right bar and the lower end of the upper right bar, and an upper node that connects the upper end of the upper left bar and the upper end of the upper right bar; and when the interval between the left node and the right node is A [mm], the vertical dimension is B [mm] and the horizontal dimension is C [mm] in the lower node or the upper node, and the thickness of the frame body is D [mm], 2A-15B+10C+90D<90 is satisfied.

Description

Lead-acid battery

[0001] The present disclosure relates to a lead-acid battery.

[0002] As an example of a lead-acid battery provided with an expanded grid as a positive electrode grid or a negative electrode grid, for example, a lead-acid battery described in JP-A-2002-117861 (hereinafter Patent Document 1) is known.

[0003] JP-A-2002-117861

[0004] Conventionally, when manufacturing an expanded grid, there has been a problem that the yield is low due to breakage of the grid bars.

[0005] The present disclosure has found a design of a grid that is less likely to cause breakage of the grid bars by devising the grid shape.

[0006] The lead-acid battery of the present disclosure is a lead-acid battery including a positive electrode plate and a negative electrode plate, wherein the positive electrode plate or the negative electrode plate includes a rectangular current collector and an active material filled in the current collector, and the current collector has a one-cell constituting the current collector being a rhombic expanded grid, and a frame surrounding the one-cell includes a lower bar located at the lower left, an upper left bar located at the upper left, a lower right bar located at the lower right, an upper right bar located at the upper right, a lower connecting portion connecting the lower ends of the lower left bar and the lower right bar, a left connecting portion connecting the upper end of the lower left bar and the lower end of the upper left bar, a right connecting portion connecting the upper end of the lower right bar and the lower end of the upper right bar, and an upper connecting portion connecting the upper ends of the upper left bar and the upper right bar. When the distance between the left connecting portion and the right connecting portion is A [mm], the vertical dimension of either the lower connecting portion or the upper connecting portion is B [mm], the horizontal dimension is C [mm], and the thickness of the frame is D [mm], 2A - 15B + 10C + 90D < 90 is satisfied.

[0007] According to the present disclosure, breakage of the grid bars during the manufacture of the expanded grid can be suppressed.

[0008] [Correction based on Rule 91 10.12.2025] Figure 1 is a partially cutaway perspective view showing the external appearance and internal structure of a lead-acid battery. Figure 2 is a schematic front view showing an example of an expanded grid according to Embodiment 1. Figure 3A is an enlarged front view showing a part of the positive or negative electrode plate of Figure 2, showing the spacing A. Figure 3B is an enlarged front view showing a part of the positive or negative electrode plate of Figure 2, showing the vertical dimension B and the horizontal dimension C. Figure 4A is an enlarged cross-sectional view showing a part of the positive or negative electrode plate, showing the thickness D. Figure 4B is an enlarged cross-sectional view showing a part of the positive or negative electrode plate, showing the thickness D when the frame is tilted. Figure 4C is an enlarged cross-sectional view showing the tab portion of the positive or negative electrode plate, showing the thickness D. Figure 5 is a table showing the relationship between the grid design and the maximum value of the angle θ at which no bar breakage occurs. Figure 6 is a table showing the grid design, the angle θ of the bars, and the grid resistance. Figure 7A is an enlarged front view showing a portion of the positive or negative electrode plate according to Embodiment 2, illustrating the three boundaries when one curved bar is divided into four equal parts. Figure 7B is an enlarged front view showing a portion of the positive or negative electrode plate according to Embodiment 2, illustrating the angle θ of the bar when the bar is undulating. Figure 8 is a table showing the relationship between the grid design, the shape of the bar, and the maximum value of the angle θ at which bar breakage does not occur.

[0009] (Summary of this embodiment) (1) The lead-acid battery of the present disclosure is a lead-acid battery comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate or the negative electrode plate includes a rectangular current collector and an active material filled in the current collector, wherein the current collector is an expanded grid in which one of the squares constituting the current collector is rhombic, and the frame surrounding the one square is a lower left rail located in the lower left, an upper left rail located in the upper left, a lower right rail located in the lower right, an upper right rail located in the upper right, and a lower rail connecting the lower end of the lower left rail and the lower end of the lower right rail. The frame has a joint, a left joint connecting the upper end of the lower left rail and the lower end of the upper left rail, a right joint connecting the upper end of the lower right rail and the lower end of the upper right rail, and an upper joint connecting the upper end of the upper left rail and the upper end of the upper right rail. When the distance between the left joint and the right joint is A [mm], the vertical dimension of either the lower joint or the upper joint is B [mm], the horizontal dimension is C [mm], and the thickness of the frame is D [mm], the condition 2A - 15B + 10C + 90D < 90 is satisfied.

[0010] In the unfolding process performed during the manufacturing of expanded grids for current collectors, a phenomenon known as "bar breakage" is known to occur, where stress concentrates at the struts or nodes, causing some struts to break. The cause of bar breakage is thought to be the large stress acting at the nodes of the frame. One attempt to alleviate the stress acting at the nodes is to simply increase the height, width, and thickness of the grid at the nodes to enlarge them. However, this method makes it difficult for the struts to stretch, requiring a large load to stretch them. Therefore, the stress acting at the nodes cannot be alleviated, and bar breakage occurs. In this disclosure, grids were manufactured by expanding and unfolding while changing the numerical values ​​of parameters A, B, C, and D. In this disclosure, by keeping the parameters A, B, C, and D within a certain range of values, it is possible to ensure both sufficient size of the nodes to distribute stress and ease of stretching of the struts, thus making bar breakage less likely.

[0011] The inventors of this application discovered that the likelihood of crossbar breakage is related to four parameters: A, the distance between the left and right joints; B, the vertical dimension of the lower or upper joint; C, the horizontal dimension of the lower or upper joint; and D, the thickness of the frame. By focusing on these four parameters and conducting expansion tests, they were able to derive the present relation.

[0012] (2) In the lead-acid battery described in (1) above, it is preferable that the angle θ between a pair of vertically adjacent bars among the left lower bar, the left upper bar, the right lower bar, and the right upper bar is 80° or more.

[0013] It is generally known that increasing the angle of the struts reduces grid resistance. However, increasing the angle of the struts can usually cause cracks to form at the joints of the frame, even if the struts do not break. In this case, the grid resistance increases.

[0014] In this disclosure, by keeping the parameters A, B, C, and D within a certain range of values, cracks in the knots can be suppressed, thereby maximizing the effect of reducing lattice resistance by increasing the angle of the frame's struts.

[0015] (3) In the lead-acid battery described in (1) or (2) above, it is preferable that the lower left bar, the upper left bar, the lower right bar, and the upper right bar are curved bars that have a curved shape, and that the curvature of the curved bars differs depending on their position in the vertical direction.

[0016] It is believed that there are two modes of cause for rafter breakage during expansion: stress concentration at each node and localized constriction at the center of each rafter (the part away from the node). Generally, rafter breakage due to stress concentration is more likely to occur, while rafter breakage due to localized constriction is relatively less likely.

[0017] When the values ​​of parameters A, B, C, and D in this disclosure are within the range of (1) above, the stress at each knot can be relaxed, thereby suppressing the occurrence of bracing breakage. However, when manufacturing a grid with a larger bracing angle than conventional grids, bracing breakage due to localized constriction becomes a limiting factor for the bracing angle. Localized constriction occurs because bracing near the knot is less likely to stretch due to the restraining force at the knot, while bracing further away from the knot stretches easily, resulting in uneven bracing elongation depending on the location. Therefore, by making the bracing curved and increasing the curvature near the knot compared to the curvature in the center of the bracing, the bracing near the knot, which is less likely to stretch in conventional examples, can be made more flexible, and the elongation of the entire bracing can be made uniform.

[0018] Therefore, by having the values ​​of parameters A, B, C, and D in this disclosure fall within the range of (1) above, and by making the curvature of the struts near the knots greater than the curvature in the central part, both modes of strut breakage can be suppressed, and thus a grid that is less prone to strut breakage can be manufactured even with a larger strut angle.

[0019] <Embodiment 1> Embodiment 1 of the present disclosure will be described with reference to Figures 1 to 6. The present disclosure is not limited to the embodiments shown in the claims, and all modifications within the meaning and scope of equivalence to the claims are intended.

[0020] (Structure of a Lead-Acid Battery) The lead-acid battery 1 is mounted on a moving object such as a four-wheeled vehicle. For example, it is installed in the engine compartment or luggage compartment of a vehicle and supplies power to the engine starting device and various vehicle loads. The lead-acid battery may be either a valve-regulated (sealed) lead-acid battery (VRLA type lead-acid battery) or a liquid-type (vented) lead-acid battery. Figure 1 shows the appearance of an example of a lead-acid battery 1 according to the embodiment of this disclosure. The lead-acid battery 1 comprises a battery case 13, a group of electrode plates 12, and a lid 16 having a pair of terminal portions 17P and 18N. In the following description, the direction in which the terminal portions 17P and 18N are aligned is the Z direction, and the direction perpendicular to the direction in which the terminal portions 17P and 18N are aligned is the X direction. The height direction of the battery case 13 (up and down direction in the figure) is the Y direction.

[0021] The battery case 13 is made of synthetic resin. The battery case 13 houses the electrode plate group 12 and the electrolyte (not shown). The battery case 13 has four outer walls and a bottom wall, and is box-shaped with an open top. The opening of the battery case 13 is closed by a lid 16 equipped with a positive electrode terminal 17P and a negative electrode terminal 18N. When replenishing water, the liquid is supplied by removing the liquid port plug 19 located on the lid 16. The liquid port plug 19 may also have the function of discharging gas generated in the cell chamber 15 to the outside of the battery. The lid 16 and the battery case 13 are molded from resin.

[0022] The inside of the battery case 13 is divided into multiple cell chambers 15 by partition walls 14. There are six cell chambers 15 arranged in the width direction of the battery case 13 (Z direction in Figure 1), and each cell chamber 15 is arranged with one electrode plate group 12 along with a flowable electrolyte (not shown).

[0023] The electrolyte contains sulfuric acid. Charging and discharging proceed through the movement of sulfate ions between the positive electrode plate 2P, the negative electrode plate 3N, and the electrolyte. During discharge, sulfate ions move to the positive electrode plate 2P and the negative electrode plate 3N, causing the density of the electrolyte to decrease. During charging, sulfate ions move from the positive electrode plate 2P and the negative electrode plate 3N into the electrolyte, causing the density of the electrolyte to increase.

[0024] Each electrode plate group 12 comprises multiple positive electrode plates 2P, multiple negative electrode plates 3N, and a separator 4 that separates adjacent electrode plates 2P and 3N. Each positive electrode plate 2P includes a positive electrode current collector 20 and a positive electrode active material 21. Each negative electrode plate 3N includes a negative electrode current collector 22 and a negative electrode active material 23. Each active material 21 and 23 is filled into each current collector 20 and 22. The main component of the positive electrode active material 21 is lead dioxide, and the main component of the negative electrode active material 23 is lead.

[0025] The separator 4 is made of an electrically insulating material. The separator 4 may be made of a microporous polyolefin sheet. The separator 4 may also include a glass mat impregnated with an electrolyte. Either the negative electrode plate 3N or the positive electrode plate 2P of the electrode plate group 12 is housed inside the separator 4. The negative electrode plate 3N and the positive electrode plate 2P are arranged alternately. The separator 4 is stacked in the direction of arrangement of the cell chambers 15 (Z direction). In each cell chamber 15, the positive electrode plate 2P and the negative electrode plate 3N are aligned in the Z direction.

[0026] As shown in Figures 1 and 2, ear portions 10P and 11N are provided on the upper part of each electrode plate 2P and 3N in the Y direction. Multiple negative electrode plates 3N are connected to one negative electrode shelf 6N. Each negative electrode plate 3N is connected to the shelf 6N via the ear portion 11N. Multiple positive electrode plates 2P are connected to one positive electrode shelf 5P. Each positive electrode plate 2P is connected to the shelf 5P via the ear portion 10P.

[0027] In the cell chamber 15 located at one end of the battery case 13, a negative electrode shelf 6N, which connects multiple negative electrode plates 3N in parallel, is connected to a through-connector 8. A positive electrode shelf 5P, which connects multiple positive electrode plates 2P in parallel, is connected to a positive electrode column 7P. The positive electrode column 7P is connected to a positive electrode terminal 17P on the outside of the cover 16.

[0028] In the cell chamber 15 located at the other end of the battery case 13, the negative electrode column 9N is connected to the negative electrode shelf 6N. The through connector 8 is connected to the positive electrode shelf 5P. The negative electrode column 9N is connected to the negative electrode terminal 18N on the outside of the cover 16.

[0029] Each through-connector 8 passes through a through-hole provided in the partition wall 14, connecting the electrode plate groups 12 of adjacent cell chambers 15 in series.

[0030] (Electrode Plates) In the lead-acid battery 1 of this disclosure, for example, paste-type electrode plates 2P and 3N are used. Each current collector 20 and 22 of electrode plates 2P and 3N is a grid (expanded grid 26) formed by expansion processing. Each current collector 20 and 22 has a rectangular shape (see Figure 2). Rectangular shape includes not only squares but also shapes that are judged to be approximately square.

[0031] The negative electrode current collector may be formed, for example, by processing a lead or lead alloy sheet. The lead alloy used for the negative electrode current collector may be any of the following: Pb-Sb alloy, Pb-Ca alloy, or Pb-Ca-Sn alloy. These lead or lead alloys may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, Zn, Fe, Ni, Te, Co, Rh, etc.

[0032] The negative electrode current collector 22 corresponds to the "current collector" in this disclosure. The negative electrode active material 23 corresponds to the "active material" in this disclosure.

[0033] The positive electrode current collector may be formed, for example, by processing a lead or lead alloy sheet. The lead alloy used for the positive electrode current collector may be any of Pb-Sb alloys, Pb-Ca alloys, or Pb-Ca-Sn alloys. In terms of corrosion resistance and mechanical strength, Pb-Ca alloys and Pb-Ca-Sn alloys are preferred. These lead or lead alloys may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, Zn, Fe, Ni, Te, Co, Rh, etc. The positive electrode current collector 20 corresponds to the "current collector" in this disclosure. The positive electrode active material 21 corresponds to the "active material" in this disclosure.

[0034] (Expanded Grid) A method for manufacturing an expanded grid includes, for example, a slitting step of making multiple slits (cuts) in a staggered pattern in a lead alloy sheet, and an unfolding step of stretching the lead alloy sheet and unfolding the multiple slits to form a mesh. The thickness of one square in the mesh is adjusted by changing the thickness of the sheet. After that, each active material of each electrode is filled into each mesh. Examples of methods for manufacturing an expanded grid include a rotary method or a reciprocating method.

[0035] Figure 2 shows an expanded grid 26 according to Embodiment 1. The expanded grid 26 comprises an upper frame frame 27 having ear portions 10P, 11N, a mesh portion 28 connected below the upper frame frame 27, and a lower frame frame 29 connected below the mesh portion 28. However, the lower frame frame 29 is not required. The mesh portion 28 has a plurality of rhombic squares 30. The term "rhombic" is not limited to strictly rhombic shapes, but includes shapes that are judged to be approximately rhombic within the range in which the effects of this disclosure are exerted.

[0036] The structure of the frame 31 surrounding one grid cell 30 will be explained using the top, bottom, left, and right directions shown in Figures 3A and 3B as a reference. The frame 31 has a lower left rail 32 located in the lower left when viewed from the center of the grid cell 30, an upper left rail 33 located in the upper left, a lower right rail 34 located in the lower right, an upper right rail 35 located in the upper right, a lower joint portion 36 connecting the lower end of the lower left rail 32 and the lower end of the lower right rail 34, a left joint portion 37 connecting the upper end of the lower left rail 32 and the lower end of the upper left rail 33, a right joint portion 38 connecting the upper end of the lower right rail 34 and the lower end of the upper right rail 35, and an upper joint portion 39 connecting the upper end of the upper left rail 33 and the upper end of the upper right rail 35.

[0037] Although the grid 30 is described in detail as a hexagonal grid, it is an example of a grid that can be evaluated as having a rhombus shape. That is, the grid 30 is the region enclosed by the inner edge of the lower left rail 32, the inner edge of the upper left rail 33, the inner edge of the lower right rail 34, the inner edge of the upper right rail 35, the inner edge of the upper joint 39, and the inner edge of the lower joint 36.

[0038] Figures 3A, 3B, and 4A are simplified diagrams showing the state in which the active materials 21 and 23 are filled inside the frame 31 of the present disclosure. As shown in Figure 3A, the distance between the left knot portion 37 and the right knot portion 38 of the frame 31 of the present disclosure is A [mm].

[0039] As shown in Figure 3B, let B [mm] be the vertical dimension of the lower joint portion 36 or upper joint portion 39 of the frame 31 of this disclosure. Let C [mm] be the horizontal dimension of the lower joint portion 36 or upper joint portion 39 of the frame 31 of this disclosure. Using the vertical, horizontal, and vertical directions shown in Figure 3B as a reference, for example, the vertical dimension B of the upper joint portion 39 is measured on the perpendicular bisector of the line segment connecting the intersection of the lower end of the upper right rail and the upper end of the lower right rail of the left-hand grid of the upper joint portion 39, and the intersection of the lower end of the upper left rail and the upper end of the lower left rail of the right-hand grid of the upper joint portion 39.

[0040] [Correction based on Rule 91 10.12.2025] Furthermore, of the frame 31 of this disclosure, the angle between a pair of vertically adjacent rails among the left lower rail 32, left upper rail 33, right lower rail 34, and right upper rail 35 is θ [°]. More specifically, the angle between the vertically adjacent left upper rail 33 and left lower rail 32 is θ, or the angle between the vertically adjacent right upper rail 35 and right lower rail 34 is θ. The θ shown in Figure 3B is approximately 90°. If the rails are undulating, as shown in Figure 7B, let P1 be the intersection of the inner edge of the upper left rail and the inner edge of the lower left rail (or the intersection of the inner edge of the upper right rail and the inner edge of the lower right rail), P2 be the upper right endpoint of the inner edge of the upper left rail (or the upper left endpoint of the inner edge of the upper right rail), and P3 be the lower right endpoint of the inner edge of the lower left rail (or the lower left endpoint of the inner edge of the lower right rail). Then, let θ[°] be the angle between the line connecting P1 and P2 and the line connecting P1 and P3.

[0041] Figure 4A is an enlarged cross-sectional view showing a portion of the positive electrode plate 2P or the negative electrode plate 3N in Figure 2. As shown in Figure 4A, the thickness of the frame 31 cut in the Z direction is denoted as D [mm]. Figure 4B shows the thickness D when the frame 31 is tilted. When the frame 31 is tilted as in Figure 4B, the thickness D of the tabs 10P and 11N shown in Figure 4C is taken as the thickness D of the frame 31. The thickness D of the frame 31 is the dimension perpendicular to the surface CS to which the blade contacts during expansion, as shown in Figure 4B. However, it is possible that the surface CS to which the blade contacts cannot be determined from the disassembled battery. In that case, both the thickness of the frame 31 and the thickness of the tabs 10P and 11N are determined by the sheet thickness before expansion, and it is thought that there would be no objection from those skilled in the art that these values ​​are the same.

[0042] When the effect that crosspiece breakage hardly occurs is exhibited in the manufacturing process of the frame body 31 surrounding one cell 30 of the expandable lattice 26 of the present disclosure, the inventor of the present application has found that the following relational expression (hereinafter referred to as relational expression 1) holds using the above A, B, C, and D.

[0043] Relational expression 1: 2A - 15B + 10C + 90D < 90

[0044] A lead-acid battery according to an embodiment of the present disclosure is a lead-acid battery comprising: (1) a positive electrode plate and a negative electrode plate, wherein the positive electrode plate or the negative electrode plate includes a rectangular current collector and an active material filled in the current collector, the current collector is an expanded grid in which one of the squares constituting the current collector is rhombic, and the frame surrounding the one square has a lower left rail located in the lower left, an upper left rail located in the upper left, a lower right rail located in the lower right, an upper right rail located in the upper right, a lower joint portion connecting the lower end of the lower left rail and the lower end of the lower right rail, a left joint portion connecting the upper end of the lower left rail and the lower end of the upper left rail, a right joint portion connecting the upper end of the lower right rail and the lower end of the upper right rail, The present invention relates to a lead-acid battery that satisfies 2A - 15B + 10C + 90D < 90, where A [mm] is the distance between the left and right node portions, B [mm] is the vertical dimension of either the lower node portion or the upper node portion, C [mm] is the horizontal dimension, and D [mm] is the thickness of the frame. (1) According to the lead-acid battery described above, if either the lower node portion or the upper node portion satisfies relation 1, then the breakage of the struts during the manufacturing of the expanded grid can be suppressed. (2) In the lead-acid battery described above, the angle θ between a pair of struts that are adjacent in the vertical direction among the lower left strut, the upper left strut, the lower right strut, and the upper right strut may be 80° or more. (2) According to the lead-acid battery described above, the effect of reducing grid resistance by increasing the angle of the struts of the frame can be maximized. (3) In the lead-acid battery described in (1) and (2) above, the lower left bar, the upper left bar, the lower right bar, and the upper right bar are curved bars, and the curvature of the curved bars may differ depending on their position in the vertical direction. According to the lead-acid battery of (3), even with a grid where the angle of the bars is large, a grid that is less prone to bar breakage can be manufactured. (4) In the lead-acid battery described in (1), (2) and (3) above, the range of the value of A is preferably 7 or more and 12 or less (7 ≤ A ≤ 12). Similarly, the range of the value of B is preferably 1.0 or more and 1.6 or less (1.0 ≤ B ≤ 1.6). Similarly, the range of the value of C is preferably 1.5 or more and 3.0 or less (1.5 ≤ C ≤ 3.0). Similarly, the range of the value of D is preferably 0.6 or more and 1.0 or less (0.6 ≤ D ≤ 1.0).According to the lead-acid battery described in (4), by adjusting the value of A, the amount of lead alloy required for manufacturing the expanded grid is further reduced, and the raw material cost can be kept low. The mesh of the expanded grid is sufficiently fine, and it is difficult for the active material to fall off from the grid. Effects such as these can be obtained. By adjusting the value of B, further, the strength of the joint part is sufficient, and it becomes difficult for the joint part to break during the expanded deployment. The joint part has flexibility, and the force required for the expanded deployment can be small. Effects such as these can be obtained. By adjusting the value of C, further, the strength of the joint part is sufficient, and it becomes difficult for the joint part to break during the expanded deployment. The joint part has flexibility, and the force required for the expanded deployment can be small. Effects such as these can be obtained.

[0045] [Test Example] The following describes the test example (see FIGS. 5 and 6).

[0046] (Manufacture of Test Battery) Each unformed negative electrode plate is housed in a bag-shaped separator, and a plate group is formed by 7 unformed negative electrode plates and 7 unformed positive electrode plates per cell. The ears of the positive electrode plates and the ears of the negative electrode plates are welded to the positive electrode shelf part and the negative electrode shelf part by the cast-on strap (COS) method, respectively. The plate group is inserted into a polypropylene battery case, electrolyte is poured, and formation is performed in the battery case to assemble a flooded lead-acid battery with a rated voltage of 12 V and a rated capacity of 32 Ah (5-hour rate capacity (capacity when discharging with a current (A) that is 1 / 5 of the numerical value of Ah described in the rated capacity))). In the battery case, 6 plate groups are connected in series. The density (g / cm 3 ) of the electrolyte after formation is 1.28.

[0047] The test example shown in FIG. 5 verifies the relationship between relational expression 1 and the difficulty of occurrence of grid breakage. When relational expression 1 is satisfied, it indicates that grid breakage is difficult to occur. The difficulty of occurrence of grid breakage is expressed by performing expanded deployment until grid breakage occurs and representing the angle θ at the time when grid breakage occurs as the maximum value of the angle θ. Therefore, the larger the angle θ, the more difficult it is for grid breakage to occur, and the smaller the angle θ, the easier it is for grid breakage to occur. Also, the maximum value of the angle θ shown in FIG. 5 is described as a relative value and may be different from the actual angle.

[0048] (Verification of relational equation 1) During the manufacturing of the grid, each grid design is expanded and unfolded so that it matches the values ​​shown in items A, B, C, and D of the table in Figure 5.

[0049] The table in Figure 5 shows the correlation between the grid design (values ​​of A, B, C, and D) and the maximum angle θ at which no cracks occur. The maximum angle θ referred to here is not the angle θ of the grid cells actually used (for example, the angle θ shown in Figures 3A and 3B), but the angle θ at which cracks occur when the grid is excessively expanded until cracks occur. As shown at the bottom of Figure 5, A, B, C, and D in Figure 5 correspond to the above A, B, C, and D explained in Figures 3A, 3B, 4A, 4B, and 4C. In Figure 5, the value of the left side of relation 1 is set to E for the purpose of reducing space. It is preferable when the maximum angle θ at which cracks do not occur is 120 or greater.

[0050] In each example and comparative example, we will explain focusing on the values ​​of E and θ. In Examples 1 to 12 of Figure 5, where rail breakage is unlikely, the value of the rail angle θ in all examples is 131 or greater. In Examples 1 to 12 of Figure 5, where rail breakage is unlikely, the values ​​of E were "68", "86", "83", "59", "77", "74", "78", "69", "87", "84", "88", and "79", respectively. All of these values ​​are less than "90". That is, Examples 1 to 12 satisfy relational equation 1.

[0051] On the other hand, in Comparative Examples 1 to 24, the value of E was 92 or greater, all greater than "90", and did not satisfy relational equation 1. In Comparative Examples 1 to 24, the angle θ value was 113 or less, and it was found that the crossbars were more prone to breaking compared to Examples 1 to 24.

[0052] Therefore, it was confirmed that when relation 1 is satisfied, the frame of the expanded grid is less likely to break.

[0053] The grid shown in Figure 2 is an expanded grid with values ​​of A = 9.8, B = 1.46, C = 2.0, D = 0.7, and E = 81. Therefore, the grid shown in Figure 2 satisfies relation 1.

[0054] In the embodiment shown in Figure 5, the range of value A is preferably 7 or more and 17 or less (7 ≤ A ≤ 17). Similarly, the range of value B is preferably 1.0 or more and 1.6 or less (1.0 ≤ B ≤ 1.6). Similarly, the range of value C is preferably 1.5 or more and 3.0 or less (1.5 ≤ C ≤ 3.0). Similarly, the range of value D is preferably 0.6 or more and 1.0 or less (0.6 ≤ D ≤ 1.0).

[0055] (Verification of Grid Resistance) The test examples in Figure 6 use Examples 2, 6, and 9 used in Figure 5, with the strut angles θ set to 70°, 80°, and 90°, and the grid resistance was measured together with the comparative example. The number of struts is changed in accordance with the change in the strut angle θ. Furthermore, after expansion, the grid is cut to a width of 101 mm and the lower frame section is cut to a height of 133 mm, thereby producing grids of the same size regardless of the values ​​of A, B, C, D, and θ. Grid resistance is measured in the grid after expansion without filling it with the active materials. The grid temperature is set to 25°C, and a HIOKI BT3562A battery high tester (using a pin-type probe) is used as the tester. When using the tester, the + probe is placed vertically on the center of the upper frame section (upper part of the current collector), and the - probe is placed vertically on the center of the lower frame section (lower part of the current collector), and the resistance value is measured. Furthermore, the grid resistance values ​​shown in Figure 6 are given as relative values ​​and may differ from the actual resistance values.

[0056] The results are shown in Figure 6. The top of Figure 6 shows the grid design items A through E, the angle θ of the bars, and the grid resistance. As shown in the bottom of Figure 6, A, B, C, and D in Figure 6 correspond to the A, B, C, and D described in Figures 3A, 3B, 4A, 4B, and 4C. The value on the left side of relation 1 is denoted as E.

[0057] Here, Examples 31 and 32 in Figure 6 correspond to Example 2 in Figure 5. Examples 33 and 34 in Figure 6 correspond to Example 6 in Figure 5. Examples 35 and 36 in Figure 6 correspond to Example 9 in Figure 5. In Examples 31 to 36, the values ​​of E are "86", "86", "74", "74", "87", and "87", respectively. Each of these values ​​is less than "90" and satisfies relation 1.

[0058] Similarly, the grid resistance values ​​for Examples 31 to 36 are "63", "43", "60", "41", "63", and "43", respectively, all of which are "63" or less. On the other hand, the grid resistance values ​​for Comparative Examples 31 to 42 are all "79" or more, indicating that the grid resistance values ​​of the examples are lower than those of the comparative examples. Furthermore, the values ​​of the strut angle θ in Examples 31 to 36 in Figure 6 are "80", "90", "80", "90", "80", and "90", respectively. That is, the value of the strut angle θ in Examples 31 to 36 is 80° or more. Therefore, it can be confirmed that when relation 1 is satisfied and the angle θ between a pair of adjacent struts in the vertical direction is 80° or more, the grid resistance value is small (for example, "63" or less).

[0059] [Correction based on Rule 91 10.12.2025] <Embodiment 2> The expanded grid 201 according to Embodiment 2 will be described with reference to Figure 7A. Embodiment 2 is a modification of Embodiment 1 in which the shape of the struts at each position is changed from straight to curved, and the same reference numerals are used for the same components as in Embodiment 1.

[0060] [Correction based on Rule 91 10.12.2025] (Expanded grid) Figure 7A is a simplified front view showing the state in which the active materials 21 and 23 are filled inside each frame 202 (expanded grid 201 of the current collector 200) according to Embodiment 2.

[0061] [Correction based on Rule 91 10.12.2025] The structure of the frame 202 will be described based on the top, bottom, left, and right directions shown in Figure 7A. The frame 202 surrounding one grid cell 203 has a lower left rail 211 located in the lower left when viewed from the center of the grid cell 203, an upper left rail 212 located in the upper left, a lower right rail 213 located in the lower right, an upper right rail 214 located in the upper right, a lower joint portion 221 connecting the lower end of the lower left rail 211 and the lower end of the lower right rail 213, a left joint portion 222 connecting the upper end of the lower left rail 211 and the lower end of the upper left rail 212, a right joint portion 223 connecting the upper end of the lower right rail 213 and the lower end of the upper right rail 214, and an upper joint portion 224 connecting the upper end of the upper left rail 212 and the upper end of the upper right rail 214.

[0062] The grid 203 is the region enclosed by the inner edge of the lower left rail 211, the inner edge of the upper left rail 212, the inner edge of the lower right rail 213, the inner edge of the upper right rail 214, the inner edge of the upper joint 224, and the inner edge of the lower joint 221.

[0063] [Correction based on Rule 91 10.12.2025] As shown in Figure 7A, regarding the shape of the bars, the lower left bar 211, upper left bar 212, lower right bar 213, and upper right bar 214 that constitute the frame 202 of one grid cell 203 are curved bars. The curvature [1 / mm] of the curved bars differs depending on the vertical position within a single curved bar.

[0064] [Correction based on Rule 91 10.12.2025] As shown in Figure 7A, one curved rail is divided into four equal parts, from top to bottom, into the first rail, second rail, third rail, and fourth rail. The boundary between the first rail and the second rail is the upper boundary 231, the boundary between the second rail and the third rail is the central boundary 232, and the boundary between the third rail and the fourth rail is the lower boundary 233.

[0065] [Test Examples] The following describes test examples (see Figure 8). The test example shown in Figure 8, like the test example shown in Figure 5, verifies the relationship between relational equation 1 and the likelihood of rail breakage.

[0066] (Verification regarding curvature) During the manufacturing of the grid, each grid design is expanded and unfolded so that the values ​​shown in items A, B, C, and D in the table shown in Figure 8 are obtained. Specifically, the grid design in this verification is obtained by changing the values ​​of items A, B, C, and D, as well as by changing the shape of the struts and the curvature values ​​at each boundary of the struts. The shape of the struts and the curvature values ​​at each boundary of the struts can be changed by changing the shape and curvature of the blade used for expansion and unfolding.

[0067] The results are shown in Figure 8. Comparative Examples 51, 54, 57, 51, 52, and 53 in the test examples of Figure 8 correspond to Comparative Examples 2, 11, 21, 2, 6, and 9 in Figure 5. In Figure 8, "straight line" for "roof shape" refers to a straight roof rib where the lower left rib, upper left rib, lower right rib, and upper right rib form a straight line, as in the roof shape of Embodiment 1. In Figure 8, "curved line" for "roof shape" refers to a curved roof rib where the lower left rib, upper left rib, lower right rib, and upper right rib form a curved roof rib, as in the roof shape of this embodiment. In Figure 8, "(average of upper and lower curvatures) / (curvature of the center)" represents the value obtained by dividing the average of the curvature of the rib at the upper boundary and the curvature of the rib at the lower boundary by the curvature of the rib at the center boundary.

[0068] The maximum angle θ at which no breakage occurred in Examples 51 to 53 was "175", "181", and "173", respectively. In Examples 51 to 53, the values ​​of E were "86", "74", and "87", respectively. Each of these values ​​is less than "90", satisfying relation 1.

[0069] Similarly, the value of "(average of upper and lower curvatures) / (central curvature)" in Examples 51 to 53 was all "1.1". This indicates that the average curvature of the upper and lower boundaries of the strut is greater than that of the central boundary of the strut. On the other hand, the value of "(average of upper and lower curvatures) / (central curvature)" in Comparative Examples 61, 63, and 65 was all "1.0". "1.1" indicates that, assuming the curvature of the upper boundary and the curvature of the lower boundary are the same, the curvature of the upper boundary is greater than the curvature of the central boundary, and the curvature of the lower boundary is greater than the curvature of the central boundary. In other words, it indicates that the curvature of the curved strut differs depending on the vertical position of the strut. On the other hand, "1.0" indicates that the curvature of the curved strut is the same depending on the vertical position of the strut, since the curvature of the upper boundary, the curvature of the lower boundary, and the curvature of the central boundary are the same.

[0070] The maximum value of angle θ when "(average of upper and lower curvatures) / (central curvature)" is "1.1" is greater than the maximum value of angle θ when "(average of upper and lower curvatures) / (central curvature)" is "1.0". Therefore, it can be confirmed that in curved struts, when the curvature differs depending on the vertical position of the strut, strut breakage is less likely to occur.

[0071] In Comparative Examples 53, 56, and 59, it was found that even if the value of "(average of upper and lower curvatures) / (central curvature)" was "1.1", the values ​​of E were "101", "129", and "115", respectively, and the relational equation 1 was not satisfied, making it more likely for the beams to break.

[0072] In comparative examples 61, 63, and 65, which used curved struts, the maximum value of angle θ was almost the same as in comparative examples 60, 62, and 64, which used straight struts. Here, in comparative examples 61, 63, and 65, the value of "(average of upper and lower curvatures) / (central curvature)" is "1.0". Therefore, it was found that even with curved struts, if the curvature of the curved strut is the same depending on the vertical position of the strut, the maximum value of angle θ will be almost the same as the maximum value of θ in the case of straight struts. In addition, in comparative examples 52, 55, and 58, relation 1 was not satisfied, and "(average of upper and lower curvatures) / (central curvature)" was "1.0". In all of these cases, the maximum value of angle θ was almost the same as in comparative examples 51, 54, and 57, which used straight struts.

[0073] In the embodiment shown in Figure 8, the range of value A is preferably 7 or more and 12 or less (7 ≤ A ≤ 12). When A is 7 or more, the amount of lead alloy required to produce the expanded grid is small, keeping raw material costs low. When A is 12 or less, the grid of the expanded grid is sufficiently fine, making it difficult for the active material to fall out of the grid. Similarly, the range of value B is preferably 1.0 or more and 1.6 or less (1.0 ≤ B ≤ 1.6). When B is 1.0 or more, the strength of the knots is sufficient, making it less likely for the knots to break during expansion. When B is 1.6 or less, the knots are flexible, requiring less force for expansion. Similarly, the range of value C is preferably 1.5 or more and 3.0 or less (1.5 ≤ C ≤ 3.0). When C is 1.5 or more, the strength of the knots is sufficient, making it less likely for the knots to break during expansion. When C is 3.0 or less, the knots are flexible, and less force is required for expansion. Similarly, the value of D is preferably in the range of 0.6 to 1.0 (0.6 ≤ D ≤ 1.0). When D is 0.6 or more, the mechanical strength of the expanded grid is high. When D is 1.0 or less, the amount of lead alloy required to manufacture the expanded grid is small, and raw material costs can be kept low.

[0074] <Other Embodiments> (1) In Embodiment 1, an example was given in which the angle θ between a pair of adjacent slats in the vertical direction is 80° or more, but it may also be 70° or more. (2) In Embodiment 2, an example was given in which the curvature of the curved slats differs depending on the position in the vertical direction, but it may also be the same. (3) The electrolyte may further contain at least one metal ion selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions. The electrolyte may be gelled as needed. Density of the electrolyte at 20°C (g / cm³) 3 The density of the electrolyte at 20°C (g / cm³) is, for example, 1.10 or higher. 3 The density (g / cm³) may be 1.35 or less. 3 ) is the value for the electrolyte of a fully charged lead-acid battery. (4) The positive electrode material may contain additives as needed. Examples of such additives include, but are not limited to, fibers (such as resin fibers), Sn, Sb, and carbonaceous materials. (5) The negative electrode material may contain additives as needed. Examples of such additives include, but are not limited to, carbonaceous materials, organic shrinkage inhibitors, barium sulfate, and fibers (such as resin fibers). (6) The positive electrode current collector may have a surface layer. The surface layer and the inner layer of the positive electrode current collector may have different compositions. The surface layer may be formed to cover the entire positive electrode current collector, or it may be formed on a part of the positive electrode current collector. The surface layer may be formed only on the grid portion, only on the lug portion, or only on the frame portion of the positive electrode current collector. (7) The negative electrode current collector may have a surface layer. The surface layer and the inner layer of the negative electrode current collector may have different compositions. The surface layer may be formed to cover the entire negative electrode current collector, or it may be formed on a part of the negative electrode current collector. The surface layer may be formed only on the grid portion, only on the lug portion, or only on the frame portion of the negative electrode current collector. The surface layer of the lug portion may contain Sn (tin) or an Sn (tin) alloy.

[0075] 1: Lead-acid battery 2P: Positive electrode plate 3N: Negative electrode plate 4: Separator 5P: Positive electrode shelf 6N: Negative electrode shelf 7P: Positive electrode column 8: Through connector 9N: Negative electrode column 10P: Lug 11N: Lug 12: Electrode plate group 13: Battery case 14: Partition wall 15: Cell chamber 16: Cover 17P: Positive electrode terminal 18N: Negative electrode terminal 19: Vent plug 20: Positive electrode current collector 21: Positive electrode active material 22: Negative electrode current collector 23: Negative electrode active material 26: Expanded grid 27: Upper frame 28: Mesh section 29: Lower frame 30: Grid 31: Frame 32: Lower left rail 33: Upper left rail 34: Lower right rail 35: Upper right rail 36: Lower joint 37: Left joint 38: Right joint 39: Upper joint 200: Current collector 201: Expanded grid 202: Frame 203: Grid 211: Lower left rail 212: Upper left rail 213: Lower right rail 214: Upper right rail 221: Lower joint 222: Left joint 223: Right joint 224: Upper joint 231: Upper boundary 232: Central boundary 233: Lower boundary

Claims

1. A lead-acid battery comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate or the negative electrode plate includes a rectangular current collector and an active material filled in the current collector, the current collector having an expanded grid in which one of the squares constituting the current collector is rhombic, and the frame surrounding the one square has a lower left rail located in the lower left, an upper left rail located in the upper left, a lower right rail located in the lower right, an upper right rail located in the upper right, a lower joint portion connecting the lower end of the lower left rail and the lower end of the lower right rail, a left joint portion connecting the upper end of the lower left rail and the lower end of the upper left rail, a right joint portion connecting the upper end of the lower right rail and the lower end of the upper right rail, and an upper joint portion connecting the upper end of the upper left rail and the upper end of the upper right rail. A lead-acid battery that satisfies 2A - 15B + 10C + 90D < 90, where A [mm] is the distance between the left and right node portions, B [mm] is the vertical dimension of either the lower or upper node portion, C [mm] is the horizontal dimension, and D [mm] is the thickness of the frame.

2. The lead-acid battery according to claim 1, wherein the angle θ between a pair of vertically adjacent bars among the left lower bar, left upper bar, right lower bar, and right upper bar is 80° or more.

3. The lead-acid battery according to claim 1 or claim 2, wherein the left lower rail, the left upper rail, the right lower rail, and the right upper rail are curved rails, and the curvature of the curved rails differs depending on their position in the vertical direction.

Images