Lead storage battery

Abstract

This lead storage battery comprises a positive electrode plate and a negative electrode plate, the positive electrode plate or the negative electrode plate including a rectangular current collector and an active material filling the current collector, wherein in the current collector, individual cells constituting the current collector make up a diamond-shaped expansion grid, and a frame surrounding each of the individual cells has four crosspieces located at the lower left, the upper left, the lower right, and the upper right, 0.18S + 48t +39d ≥ 100 is satisfied, where S [mm2] is the area of the individual cell, t [mm] is the thickness of the frame, and d [mm] is the width of the crosspieces, and an angle θ between two of the crosspieces adjacent to each other in a vertical direction is 80° or more.

Description

lead acid battery

[0001] This disclosure relates to lead-acid batteries.

[0002] Lead-acid batteries use positive and negative electrode grids made of lead or lead alloys for their positive and negative electrode plates. These grids have a mesh structure. The positive and negative electrode plates are manufactured by filling this mesh structure with active material. As an example of a grid in which the squares constituting the mesh structure are opened in a roughly rhomboid shape, the expanded grid described in International Publication No. 2013 / 073091 (see Patent Document 1 below) is known.

[0003] International Publication No. 2013 / 073091

[0004] When a lead-acid battery deteriorates, the active material shrinks, causing cracks to form. These cracks significantly increase internal resistance, leading to a premature end of life.

[0005] This disclosure focuses on the pattern of cracks that occur and finds that the internal resistance does not increase easily when the pattern is predetermined.

[0006] The lead-acid battery of this 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, the current collector having one grid cell that is a rhombus-shaped expanded grid, and the frame surrounding the one grid cell has four bars located at the lower left, upper left, lower right, and upper right, and the area of ​​the grid cell is S [mm²] ２ When the thickness of the frame is t [mm] and the width of the crossbar is d [mm], the condition 0.18S + 48t + 39d ≥ 100 is satisfied, and the angle θ between two adjacent crossbars in the vertical direction is 80° or more.

[0007] According to this disclosure, it is possible to manufacture lead-acid batteries in which the internal resistance does not easily increase.

[0008] [Correction based on Rule 91 16.12.2025] 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 negative electrode plate of Figure 2, showing the area S. Figure 3B is an enlarged front view showing a part of the negative electrode plate of Figure 2, showing the dimension d of the width of the strut and the angle θ of the strut. Figure 4A is an enlarged cross-sectional view showing a part of the negative electrode plate of Figure 2, showing the thickness t. Figure 4B is an enlarged cross-sectional view showing a part of the positive or negative electrode plate, showing the thickness t 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 t. Figure 5A is an enlarged schematic diagram showing a crack (Type A) that has occurred vertically on a part of the negative electrode plate of Figure 2. Figure 5B is a schematic, magnified view showing a crack (Type B) that occurred horizontally in a portion of the negative electrode plate in Figure 2. Figure 5C is a schematic, magnified view showing a crack (Type C) that occurred in a manner surrounding a grid in a portion of the negative electrode plate in Figure 2. Figure 6 is a table showing the relationship between the grid design, the crack type, and the AC-IR rise value. Figure 7A is a front view, magnified view of a portion of the negative electrode plate according to Embodiment 2, schematically showing the crack state when there is waviness in the struts. Figure 7B is a front view, magnified view of a portion of the negative electrode plate according to Embodiment 2, showing the angle θ of the struts when there is waviness in the struts. Figure 8 is a table showing the relationship between the grid design, the arithmetic mean waviness of the struts, and the AC-IR rise value.

[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 comprises a rectangular current collector and an active material filled in the current collector, wherein one of the squares constituting the current collector is a diamond-shaped expanded grid, and the frame surrounding the one square has four bars located at the lower left, upper left, lower right, and upper right, and the area of ​​the square is S [mm ２], where the thickness of the frame is t [mm] and the width of the crossbar is d [mm], the condition 0.18S + 48t + 39d ≥ 100 is satisfied, and the angle θ between two adjacent crossbars in the vertical direction is 80° or more. A rectangular shape is not limited to a strictly rectangular shape, but includes shapes that are evaluated as rectangular within the scope of the effects of this disclosure. A rhombic shape is not limited to a strictly rhombic shape, but includes shapes that are evaluated as rhombic within the scope of the effects of this disclosure.

[0010] When a lead-acid battery deteriorates, the negative electrode active material filling the current collector shrinks, causing cracks to form in the negative electrode active material. These cracks significantly increase the battery's internal resistance, leading to a shortened lifespan. The types of cracks that can occur include vertical cracks (hereinafter referred to as Type A), horizontal cracks (hereinafter referred to as Type B), and cracks that surround a grid (hereinafter referred to as Type C). The inventors of this invention have discovered that when the cracks that occur are of Type A, the internal resistance does not increase as much.

[0011] When the resulting crack is of type A, the conductive path from the top to the bottom of the electrode plate is less likely to be severed, so the internal resistance is less likely to increase. On the other hand, when the resulting crack is of type B or C, the conductive path from the top to the bottom of the electrode plate is more likely to be severed, so the internal resistance is likely to increase. The inventors of this application have discovered that the type of crack that is likely to occur is determined by the design of the grid of the expanded grid. The grid design is performed using the area S of the grid, the thickness t of the grid, the width d of the struts, and the angle θ between two adjacent struts in the vertical direction of the frame surrounding the grid grid as parameters. The grid is manufactured by expanding by changing the values ​​of each of these parameters.

[0012] If the area S of the grid cells in the manufactured expanded lattice is small, the forces acting due to the contraction of the active material cannot be dispersed, resulting in the occurrence of many C-type cracks. Also, if the angle θ between two adjacent struts in the vertical direction of the frame surrounding the grid cells of the expanded lattice is small, the direction of the bonding force acting between the active material and the struts becomes horizontal, so the bonding force in the vertical direction is weaker, resulting in the occurrence of many B-type cracks.

[0013] The inventors of this application discovered that the type of crack that is likely to occur is determined by keeping the values ​​of each parameter S, t, d, and θ within a certain range, and that when 0.18S + 48t + 39d ≥ 100 and θ is 80° or greater, type A cracks occur frequently. By designing the grid squares in the manufacturing process of the expanded grid so that type A cracks occur, it is possible to manufacture an expanded grid in which the internal resistance does not easily increase. By determining the design of the expanded grid in this way, the type of crack that occurs due to the shrinkage of the active material accompanying the deterioration of the lead-acid battery is determined. Therefore, it is possible to manufacture an expanded grid in which the internal resistance does not easily increase. This makes it possible to provide a lead-acid battery in which the internal resistance does not easily increase. The inventors of this application discovered that the type of crack that is likely to occur in the electrode plate is related to four parameters: the area S of the grid, the thickness t of the grid, the width d of the struts, and the angle θ between two adjacent struts in the vertical direction of the frame surrounding the grid squares. Then, by focusing on these four parameters and conducting battery tests, the inventors were able to find this relationship.

[0014] (2) In the lead-acid battery described in (1) above, it is preferable that the arithmetic mean curvature of the ribs of the frame is 50 μm or more.

[0015] The arithmetic mean swell is measured using a 3D shape measuring machine. (The cutoff value is λ) ｃ = 2.5 mm, λ ｆ (=25 mm). When the arithmetic mean undulation of the curved struts of the frame is 50 μm or more, cracks preferentially occur in some of the struts extending downward from the upper node and some of the struts extending upward from the lower node (the recessed parts compared to the straight struts). On the other hand, cracks are less likely to occur in the peripheral parts of the left or right node (the protruding parts compared to the straight struts). In that case, since the conductive path from the top to the bottom of the electrode plate is not completely lost, it is thought that the increase in internal resistance can be further suppressed compared to the case of a lead-acid battery incorporating an expanded grid with a frame made of straight struts as its constituent elements.

[0016] <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.

[0017] (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.

[0018] 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.

[0019] 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 one electrode plate group 12 is placed in each cell chamber 15 along with a flowable electrolyte (not shown).

[0020] 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.

[0021] 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.

[0022] 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.

[0023] As shown in Figures 1 and 2, lugs 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 lugs 11N. Multiple positive electrode plates 2P are connected to one positive electrode shelf 5P. Each positive electrode plate 2P is connected to the positive electrode shelf 5P via the lugs 10P.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] (Positive electrode plate, negative electrode plate) In the lead-acid battery 1 of this disclosure, for example, a paste-type positive electrode plate 2P and a negative electrode plate 3N are used. Each current collector 20, 22 of each electrode plate 2P, 3N is a grid (expanded grid 26) formed by expansion processing. Each current collector 20, 22 has a rectangular shape (see Figure 2). Rectangular shape includes not only squares but also shapes that are judged to be approximately square.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] (Expanded grids and cracks) 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 of the mesh squares is adjusted by changing the thickness of the sheet. Thereafter, each active material of each electrode is filled into each mesh square. Examples of methods for manufacturing expanded grids include a rotary method or a reciprocating method.

[0032] 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 and 11N, a mesh portion 28 connected below the upper frame frame 27, and a lower frame frame 29 connected below the mesh portion 28. The mesh portion 28 has a plurality of rhombic squares 30. The lower frame frame 29 is optional.

[0033] The structure of the frame 31 surrounding one grid cell 30 will be described using the up, down, left, and right directions shown in Figures 3A and 3B as reference. The frame 31 has four crossbars located at the bottom left, top left, bottom right, and top right. In detail, it has a bottom left crossbar 32 located at the bottom left when viewed from the center of the grid cell 30, a top left crossbar 33 located at the top left, a bottom right crossbar 34 located at the bottom right, a top right crossbar 35 located at the top right, a lower joint portion 36 connecting the bottom end of the bottom left crossbar 32 and the bottom end of the bottom right crossbar 34, a left joint portion 37 connecting the top end of the bottom left crossbar 32 and the bottom end of the top left crossbar 33, a right joint portion 38 connecting the top end of the bottom right crossbar 34 and the bottom end of the top right crossbar 35, and an upper joint portion 39 connecting the top end of the top left crossbar 33 and the top end of the top right crossbar 35.

[0034] 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.

[0035] Figures 3A, 3B, and 4A are simplified diagrams showing the state in which the active material 23 is filled inside the frame 31 of the present disclosure. As shown in Figure 3A, the area of ​​the grid 30 of the present disclosure is S [mm²]２ ]

[0036] [Correction based on Rule 91 16.12.2025] As shown in Figure 3B, the width dimension of the struts in this disclosure is d [mm]. In this specification, the strut width d means the vertical dimension with respect to the positive or negative electrode plate in one of the four struts of the frame. However, if the four struts of the frame have strut widths d of different values, the strut width d of any one of the four struts of the frame is defined as the strut width d if the value of the strut width d satisfies the relation 0.18S + 48t + 39d ≥ 100. The angle between two vertically adjacent struts constituting the grid 30 of this disclosure is θ [°]. More specifically, the angle between a pair of vertically adjacent struts among the lower left strut 32, upper left strut 33, lower right strut 34, and upper right strut 35 of the frame 31 is θ [°]. More specifically, the angle between the vertically adjacent upper left rail 33 and lower left rail 32 is defined as θ, or the angle between the vertically adjacent upper right rail 35 and lower right rail 34 is defined as θ. For example, the angle θ between two vertically adjacent rails that constitute the grid 30 shown in Figure 3B is approximately 81°. If the rails are curved, as shown in Figure 7B, when the intersection of the inner edge of the upper right rail and the inner edge of the lower right rail (or the intersection of the inner edge of the upper left rail and the inner edge of the lower left rail) is P1, the upper left endpoint of the inner edge of the upper right rail (or the upper right endpoint of the inner edge of the upper left rail) is P2, and the lower left endpoint of the inner edge of the lower right rail (or the lower right endpoint of the inner edge of the lower left rail) is P3, the angle between the line connecting P1 and P2 and the line connecting P1 and P3 is defined as θ [°].

[0037] Figure 4A is a cross-sectional view showing an enlarged part of the negative electrode plate 3N in Figure 2. As shown in Figure 4A, let the thickness of the frame 31 (grid 30) cut in the Z direction be t [mm]. Figure 4B shows the thickness t when the frame 31 is tilted. When the frame 31 is tilted as in Figure 4B, the thickness t of the frame 31 is taken as the thickness D of the ears 10P and 11N shown in Figure 4C. The thickness t of the frame 31 is, as shown in Figure 4B, the dimension in the direction perpendicular to the surface CS where the blade abuts during the expandable deployment. However, it is considered that there may be cases where the surface CS where the blade abuts cannot be determined from the disassembled battery. In that case, both the thickness of the frame 31 and the thickness of the ears 10P and 11N are determined by the sheet thickness before deployment, and it is considered that those skilled in the art would have no objections to these values being the same.

[0038] In a negative electrode plate of a deteriorated lead-acid battery, it is known that physical deterioration (cracks) may occur at the interface between the negative electrode current collector and the active material due to a decrease in the adhesion force between the negative electrode current collector and the active material. When the internal resistance increases due to the occurrence of cracks. When the lead-acid battery 1 assembled with the expandable grid 26 composed of the frame 31 surrounding one grid 30 of the present disclosure deteriorates, for example, the adhesion force between the negative electrode current collector and the active material decreases, and cracks occur at the interface between the negative electrode current collector (frame) and the active material, and it is considered that the internal resistance increases.

[0039] Regarding the cracks 40A, 40B, and 40C in the frame 31 surrounding one grid 30, they are classified into three types according to the location where the cracks occur when the cracks occur (see Figures 5A, 5B, and 5C). Figures 5A, 5B, and 5C are diagrams simply showing the state in which the active material 23 is filled in the frame 31 of the present disclosure. In the state before repeating charge and discharge, the current collector 22 and the active material 23 are sufficiently bonded. However, as shown in Figures 5A, 5B, and 5C, in the state where the charge and discharge are repeated and the cracks 40A, 40B, and 40C occur, the current collector 22 and the active material 23 are in a fragile bonding state.

[0040] Descriptions will be made based on the up, down, left, and right directions shown in FIGS. 5A, 5B, and 5C. Also, the vertical direction refers to the up and down directions shown, and the horizontal direction refers to the left and right directions shown. FIG. 5A shows a crack 40A in a state generated in the vertical direction (hereinafter referred to as Type A). For example, it occurs in the upper left bar 33, the lower left bar 32, the upper node portion 39, and the lower node portion 36. Also, although not shown, for example, it may occur in the upper right bar 35, the lower right bar 34, the upper node portion 39, and the lower node portion 36.

[0041] FIG. 5B shows a crack 40B in a state generated in the horizontal direction (hereinafter referred to as Type B). For example, it occurs in the upper left bar 33, the upper right bar 35, and the upper node portion 39. FIG. 5C shows a crack 40C in a state generated so as to surround the mesh 30 (hereinafter referred to as Type C). For example, it occurs in the lower left bar 32, the upper left bar 33, the upper node portion 39, the upper right bar 35, and the lower right bar 34.

[0042] It serves as a conductive path from the upper part to the lower part of the electrode plate composed of the current collector and the active material. When a Type A crack occurs, even if the path of the upper left bar 33 in the conductive path is cut off, the path of the upper right bar 35 remains, and it is considered that the conductive path is difficult to be cut off and the internal resistance is difficult to increase. When a Type B or Type C crack occurs, since the conductive paths of the upper left bar 33 and the upper right bar 35 are cut off, it is considered that the internal resistance increases.

[0043] Therefore, when a Type A crack 40A occurs, it is considered that the internal resistance is less likely to increase compared to the case where a Type B crack 40B occurs and the case where a Type C crack 40C occurs. Therefore, when the lead storage battery 1 deteriorates, the design of the mesh 30 is performed so that the above Type A crack 40A occurs in the negative electrode active material 23 filled in the frame body 31 (negative electrode current collector 22) surrounding one mesh 30 of the expandable grid 26 of the present disclosure.

[0044] When exerting the effect that the internal resistance is less likely to rise, the inventor of the present application found that the following relational expression (hereinafter referred to as relational expression 1) holds (that is, is satisfied) using the above S, t, d, and θ, and the angle θ formed by two adjacent bars in the vertical direction is 80° or more.

[0045] Relational equation 1: 0.18S + 48t + 39d ≥ 100

[0046] Furthermore, the inventors of the present invention have found that when the above relational equation 1 holds true and the angle θ between two adjacent stiles in the vertical direction is 80° or greater, a large number of Type A cracks 40A occur.

[0047] A lead-acid battery according to the 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 having one grid cell that is a rhombus-shaped expanded grid, and the frame surrounding the one grid cell has four bars located at the lower left, upper left, lower right, and upper right, and the area of ​​the grid cell is S [mm²] ２The present invention relates to a lead-acid battery wherein, when the thickness of the frame is t [mm] and the width of the struts is d [mm], the following conditions are met: 0.18S + 48t + 39d ≥ 100, and the angle θ between two adjacent struts in the vertical direction is 80° or more. The lead-acid battery described in (1) above makes it possible to manufacture an expanded grid in which the internal resistance does not easily increase, thereby providing a lead-acid battery in which the internal resistance does not easily increase. (2) In the lead-acid battery described in (1) above, the arithmetic mean waviness of the struts of the frame may be 50 μm or more. The lead-acid battery described in (2) above makes it possible to provide a lead-acid battery in which the internal resistance does not easily increase. (3) In the lead-acid batteries described in (1) and (2) above, the range of the value of S is preferably 120 or more and 180 or less (120 ≤ S ≤ 180). Similarly, the range of the value of t is preferably 0.8 or more and 1.0 or less (0.8 ≤ t ≤ 1.0). Similarly, the range of the value of d is preferably 0.5 or more and 0.9 or less (0.5 ≤ d ≤ 0.9). Similarly, the range of the value of the angle θ between two adjacent struts in the vertical direction is preferably 80 or more and 90 or less (80 ≤ θ ≤ 90). According to the lead-acid battery described in (3), depending on the value of S, raw material costs can be kept even lower and the active material is less likely to fall out of the expanded grid; depending on the value of t, the mechanical strength of the expanded grid is high and raw material costs can be kept low; depending on the value of d, the mechanical strength of the expanded grid is high and raw material costs can be kept low; and depending on the value of θ, strut breakage can be made less likely.

[0048] [Test Example] The following describes a test example (see Figure 6).

[0049] (Verification of relational equation 1) An expanded grid is fabricated using the parameters shown for each of S, t, d, and θ in Figure 6. The number of wires was changed according to each of S, t, d, and θ. Furthermore, after the grid is unfolded, it is cut to a width of 101 mm and the lower frame is cut to a height of 133 mm, thereby fabricating a grid of the same size regardless of the values ​​of S, t, d, and θ. In Figure 6, the value of the left side of relational equation 1 is set to F in order to reduce space. A battery is fabricated using this grid as the negative electrode plate. (Fabrication of test battery) Each unformed negative electrode plate is placed in a bag-shaped separator, and an electrode plate group is formed with 7 unformed negative electrode plates and 7 unformed positive electrode plates per cell. The tabs of the positive electrode plates and the tabs of the negative electrode plates are welded to the positive electrode shelf and negative electrode shelf, respectively, using the cast-on-strap (COS) method. The electrode plates are inserted into a polypropylene battery case, the electrolyte is poured in, and the battery is reformed within the case to assemble a liquid lead-acid battery with a rated voltage of 12V and a rated capacity of 32Ah (5-hour rate capacity (capacity when discharged at a current (A) of 1 / 5 of the Ah value stated in the rated capacity)). Six electrode plates are connected in series within the battery case. The density of the electrolyte after reforming is (g / cm³). 3 ) is 1.28.

[0050] The test example shown in Figure 6 verifies the relationship between relation 1 and the effect of making it difficult for internal resistance to increase, that is, the occurrence of many Type A cracks. It shows that when relation 1 is satisfied and the angle θ between two adjacent ribs in the vertical direction is 80° or more, internal resistance does not increase easily, that is, many Type A cracks occur.

[0051] (Verification of relational equation 1) A battery is fabricated using the prepared grid as the negative electrode plate, and a cycle test (light load life test described in JIS D5301:2019) is performed. The AC-IR is measured before and after the test, and the difference is recorded in the AC-IR rise value (relative value) item. The details of the test conditions and the method of measuring AC-IR are as follows. <Cycle test conditions> Discharge is performed at a discharge current of 25A for 4 minutes, followed by charging at a charging voltage of 14.8V (limiting current of 25A) for 10 minutes. This discharge and charge cycle is considered one cycle. During the test, the ambient temperature of the storage battery is set to 40°C (in a water bath). During the test, the battery is left for 56 hours every 480 cycles. After the waiting period, discharge is performed at a discharge current of 340A for 30 seconds. Then, charging is performed at a charging voltage of 14.8V (limiting current of 25A) for 10 minutes. This discharge and charge is also added to the number of cycles. The test is terminated after 2406 cycles. <AC-IR Measurement Method> The battery temperature is set to 25°C, and the AC-IR between terminals is measured using a HIOKI BT3562A battery high tester.

[0052] Furthermore, after the test, the battery was disassembled, and the types of cracks that occurred on the negative electrode plate of the battery were tallied for each grid cell. The results of the most frequently occurring crack types are shown in the "Crack Type" section of Figure 6. As a criterion for distinguishing between the example and the comparative example, for example, if the AC-IR rise value (relative value), which is an indicator that the internal resistance does not rise easily, is 75 or less, it may be designated as the example, and if it is greater than 75, it may be designated as the comparative example.

[0053] In each example and comparative example, we will explain focusing on the value of F and the AC-IR rise value (relative value). In Examples 1 to 10 of Figure 6, where the internal resistance does not rise easily, the AC-IR rise value for all examples is 73 or less. In Examples 1 to 10 of Figure 6, where the internal resistance does not rise easily, the values ​​of F were "105", "105", "106", "106", "100", "100", "108", "108", "116", and "116". All of these values ​​are greater than or equal to "100". That is, Examples 1 to 10 satisfy relational equation 1.

[0054] Furthermore, the values ​​of the angle θ between two adjacent slats in the vertical direction are "80", "90", "80", "90", "80", "90", "80", "90", "80", and "90". Therefore, this corresponds to the case where relation 1 is satisfied and the angle θ between two adjacent slats in the vertical direction is 80° or greater.

[0055] On the other hand, in Comparative Examples 1 to 26, the values ​​of F are "80", "80", "80", "87", "87", "87", "95", "95", "95", "89", "89", "89", "97", "97", "97", "105", "90", "90", "90", "98", "98", "98", "106", "100", "108", and "116".

[0056] Comparative examples where the value of F is less than "100" do not satisfy relational equation 1. The values ​​of F in Comparative Examples 16, 23, 24, 25, and 26 are all "100" or greater. Therefore, Comparative Examples 16, 23, 24, 25, and 26 satisfy relational equation 1. Also, the values ​​of θ in Comparative Examples 16, 23, 24, 25, and 26 are all "70". Comparative Examples 16, 23, 24, 25, and 26 satisfy relational equation 1, but they do not fall under the case where the angle θ between two adjacent struts in the vertical direction is 80° or greater. Furthermore, the AC-IR rise values ​​in Comparative Examples 16, 23, 24, 25, and 26 are all "86" or greater, which falls under the case where internal resistance is likely to rise.

[0057] Based on the above results regarding the F value and AC-IR rise value in each example and comparative example, the type of crack is considered. The type of crack in Examples 1 to 10 is all type A. Among the comparative examples, the types of cracks in Comparative Examples 16, 23, 24, 25, and 26 that satisfy relational equation 1 are either type B or type C. Therefore, the type of crack in each comparative example that satisfies relational equation 1 is not all type A.

[0058] In each comparative example that did not satisfy relational equation 1 (comparative examples 1 through 15, and comparative examples 17 through 22), the crack type was always type C. Therefore, the crack type in each comparative example that did not satisfy relational equation 1 was not all type A.

[0059] Therefore, when relation 1 is satisfied (valid), and the angle θ between two adjacent slats in the vertical direction is 80° or more, it can be confirmed that the internal resistance does not increase easily and that many Type A cracks occur.

[0060] The grid shown in Figure 2 is an expanded grid with an S value of 180, a t value of 1.0, a d value of 0.9, and a θ value of approximately 81. Therefore, the grid shown in Figure 2 satisfies relation 1, and the angle θ between two adjacent struts in the vertical direction is 80° or greater.

[0061] In the embodiment shown in Figure 6, the range of the value of S is preferably 120 or more and 180 or less (120 ≤ S ≤ 180). When S is 120 or more, the amount of lead alloy required to produce the expanded lattice is small, and raw material costs can be kept low. When S is 180 or less, the active material is less likely to fall out of the expanded lattice. Similarly, the range of the value of t is preferably 0.8 or more and 1.0 or less (0.8 ≤ t ≤ 1.0). When t is 0.8 or more, the mechanical strength of the expanded lattice is high. When t is 1.0 or less, raw material costs can be kept low. Similarly, the range of the value of d is preferably 0.5 or more and 0.9 or less (0.5 ≤ d ≤ 0.9). When d is 0.5 or more, the mechanical strength of the expanded lattice is high. When d is 0.9 or less, raw material costs can be kept low. Similarly, the range of the angle θ between two adjacent struts in the vertical direction is preferably 80 or more and 90 or less (80 ≤ θ ≤ 90). When θ is 80 or greater, the effects of this disclosure are realized, and when θ is 90 or less, there is no need to greatly stretch the struts during expansion, making strut breakage less likely.

[0062] [Correction based on Rule 91 16.12.2025] <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 a straight shape to a wavy shape, and the same reference numerals are used for the same components as in Embodiment 1.

[0063] [Correction based on Rule 91 16.12.2025] (Expanded grid) Figure 7A is a simplified front view showing the state in which the active material 23 is filled inside each frame 202 (expanded grid 201 of the current collector 200) according to Embodiment 2.

[0064] [Correction based on Rule 91 16.12.2025] 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.

[0065] 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.

[0066] [Correction based on Rule 91 16.12.2025] 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 bars that have a curved shape with a undulation. The magnitude of the undulation of these bars can be calculated by the arithmetic mean undulation [μm].

[0067] [Correction based on Rule 91 16.12.2025] When a lead-acid battery 1 assembled with an expanded grid 201 consisting of a frame 202 surrounding one cell 203 of the present disclosure deteriorates, it is thought that, for example, the bonding force between the negative electrode current collector and the active material decreases, cracks occur at the interface between the negative electrode current collector and the active material, and the internal resistance increases. The shape of the crack 240 in the frame 202 surrounding one cell 203 is as shown in Figure 7A. In detail, the shape of the crack 240 in this embodiment is similar to the A-type crack 40A. The shape of the crack 240 in this embodiment is, for example, a shape that extends from part or all of the upper node portion 224 to part of the upper left rail 212 and a shape that extends from part or all of the lower node portion 221 to the lower left rail 211.

[0068] The inventors of this application have discovered that when relational equation 1 holds true, and the angle θ between two adjacent slats in the vertical direction is 80° or more, and furthermore, the arithmetic mean waviness of the slats of the frame 202 is 50 μm or more, the internal resistance is less likely to increase further.

[0069] [Test Example] The following describes a test example (see Figure 8).

[0070] (Preparation of test battery) Each unformed negative electrode plate is placed in a bag-shaped separator, and an electrode plate group is formed with 7 unformed negative electrode plates and 7 unformed positive electrode plates per cell. The tabs of the positive electrode plates and the tabs of the negative electrode plates are welded to the positive electrode shelf and negative electrode shelf, respectively, using the cast-on-strap (COS) method. The electrode plate group is inserted into a polypropylene battery case, electrolyte is poured in, and the electrode formation process is carried out inside the battery case to assemble a liquid lead-acid battery with a rated voltage of 12V and a rated capacity of 32Ah (5-hour rate capacity (capacity when discharged at a current (A) of 1 / 5 of the Ah value stated in the rated capacity)). Six electrode plate groups are connected in series inside the battery case. Density of the electrolyte after formation (g / cm³) 3 ) is 1.28.

[0071] The test example shown in Figure 8, similar to the test example shown in Figure 6, verifies the relationship between satisfying relational equation 1 and the fact that the internal resistance does not easily increase when the angle θ between two adjacent vertical supports is 80° or more.

[0072] (Verification of Arithmetic Mean Warp of the Bars) An expanded grid is fabricated using the parameters shown for each of S, t, d, and θ in Figure 8. The number of bars is changed according to each of S, t, d, and θ. Furthermore, after unfolding the grid, it is cut to a width of 101 mm, and the lower frame is cut to a height of 133 mm, thereby fabricating a grid of the same size regardless of the values ​​of S, t, d, and θ. A battery is fabricated using this grid as the negative electrode plate, and a cycle test (light load life test described in JIS D5301:2019) is performed. The AC-IR is measured before and after the test, and the difference is recorded in the AC-IR rise value (relative value) item in Figure 8. The details of the test conditions and the method of measuring AC-IR are the same as in the verification of relational equation 1. In Figure 8, the value of the left side of relational equation 1 is set to F for the purpose of reducing space. It is preferable when the AC-IR rise value (relative value), which is an indicator that the internal resistance does not rise easily, is 50 or less.

[0073] During the manufacturing of the grid, each grid design is expanded and unfolded so that the values ​​of S, t, d, and θ in the table shown in Figure 8 are obtained. Specifically, the grid design in this verification is changed by changing the values ​​of S, t, d, and θ, as well as changing the "arithmetic mean waviness value of the slats" that make up the frame. The "arithmetic mean waviness value of the slats" that make up the frame can be changed by changing the arithmetic mean waviness value of the blade used for expansion and unfolding. Note that Comparative Examples 51, 55, and Example 1 in the test examples of Figure 8 correspond to Comparative Examples 1, 16, and Example 1 in Figure 6. In the comparative examples and examples of the test examples shown in Figure 6, the slats that make up the frame shown in Example 1 are straight and have no waviness. In comparative examples 51, 55, and Example 1, which are constructed with straight slats in this way, the arithmetic mean waviness value of the slats of the frame is 0.

[0074] The results are shown in Figure 8.

[0075] The AC-IR rise values ​​(relative values) for Examples 51 and 52 are "48" and "45," respectively. In Examples 51 and 52, the value of F is "105" and "105," respectively. The value of F in each example is always "100" or greater. That is, Examples 51 and 52 satisfy relation 1. Also, in Examples 51 and 52, the value of the angle θ between two adjacent rafters in the vertical direction is "80" and "80," respectively. That is, in Examples 51 and 52, the angle θ between two adjacent rafters in the vertical direction is 80° or greater. That is, Examples 51 and 52 satisfy relation 1, and the angle θ between two adjacent rafters in the vertical direction is 80° or greater. Also, in Examples 51 and 52, the value of the arithmetic mean wobble of the rafters is "50" and "75," respectively. The arithmetic mean waviness values ​​of each rib are all 50 or greater. Therefore, it was confirmed that the internal resistance does not increase easily when relation 1 holds, the angle θ between two adjacent ribs in the vertical direction is 80° or greater, and the arithmetic mean waviness of the frame ribs is 50 μm or greater.

[0076] On the other hand, the range of the arithmetic mean undulation values ​​of the beams in Comparative Examples 51 to 60 is between 0 and 75. However, Comparative Examples 51 to 54 did not satisfy relation 1. Comparative Examples 55 to 58 did not satisfy the condition that the angle θ between two adjacent beams in the vertical direction is 80° or more.

[0077] In the embodiment shown in Figure 8, the value of S is preferably 120 (S = 120). Similarly, the value of t is preferably 1.0 (t = 1.0). Similarly, the value of d is preferably 0.9 (d = 0.9). Similarly, the range of the angle θ between two adjacent struts in the vertical direction is preferably 80 (θ = 80).

[0078] <Other Embodiments> (1) In the A type of Embodiment 1, it was exemplified that cracks occur in the upper left bar, the lower left bar, the upper node portion, and the lower node portion, and that cracks occur in the upper right bar, the lower right bar, the upper node portion, and the lower node portion. However, for example, it may be a shape that continues from a part or all of the upper node portion to a part of the upper left bar and a shape that continues from a part or all of the lower node portion to a part of the lower left bar. (2) In Embodiment 2, it was exemplified that the angle θ formed by two adjacent bars in the vertical direction constituting the mesh is 80° or more, but the angle θ formed by two adjacent bars in the vertical direction constituting the mesh may be 81° or more. (3) The electrolytic solution may further contain at least one metal ion selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions, etc. The electrolytic solution may be gelled as necessary. The density (g / cm 3 ) of the electrolytic solution at 20°C is, for example, 1.10 or more. The density (g / cm 3 ) of the electrolytic solution at 20°C may be 1.35 or less. Note that these densities (g / cm 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.

[0079] 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 40A: Crack 40B: Crack 40C: Crack 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 240: Crack

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 one grid cell that is a rhombus-shaped expanded grid, and the frame surrounding the one grid cell has four bars located at the bottom left, top left, bottom right, and top right, and the area of ​​the grid cell is S [mm²] ２ A lead-acid battery in which, when the thickness of the frame is t [mm] and the width of the struts is d [mm], the condition 0.18S + 48t + 39d ≥ 100 is satisfied, and the angle θ between two adjacent struts in the vertical direction is 80° or more.

2. The lead-acid battery according to claim 1, wherein the arithmetic mean waviness of the ribs of the frame is 50 μm or more.

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