Positive electrode collector for lead storage battery and manufacturing method of collector for lead storage battery

Abstract

To inhibit deterioration of the yield of a collector.SOLUTION: A first positive electrode collector 32 of the disclosure is used for a lead storage battery 10 and includes: a frame bone 33 forming an outer peripheral portion of the first positive electrode collector 32; and an inner bone 34 spanned in a lattice form in the frame bone 33. The first positive electrode collector 32 is formed by a rolled material RM having a striped structure. The inner bone 34 includes reinforcement bones 35. An area of a cross section perpendicular to an extending direction of the reinforcement bone 35 is larger than an area of a cross section perpendicular to an extending direction of the frame bone 33.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a positive electrode current collector for a lead-acid battery and a method for manufacturing a current collector for a lead-acid battery. [Background technology]

[0002] A known example of a positive electrode current collector for a lead-acid battery is a grid described in JP 2014-235844 A (Patent Document 1 below). This grid includes a rectangular frame, tabs protruding from a first side of the frame to the outside, a main frame connecting the first side with a second side opposite the first side, and a plurality of first sub-ribs branching from at least the main frame and extending diagonally toward both sides of the main frame as an axis and toward the second side, with at least some of the first sub-ribs being bent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-235844 Summary of the Invention [Problem to be solved by the invention]

[0004] When cutting out the above-mentioned lattices from the lattice roll, the cutting position is the boundary between the frame frames of two adjacent lattices. At this time, it is preferable to cut so that the width of each frame frame is uniform, but if the cutting accuracy is low, the frame width will vary, which is one of the causes of a decrease in the yield of the lattices.

[0005] The present disclosure was completed in light of the above circumstances, and aims to suppress a decrease in yield of current collectors. [Means for solving the problem]

[0006] A positive electrode current collector for a lead-acid battery according to one aspect of the present invention is a positive electrode current collector for use in a lead-acid battery, comprising: a frame that forms an outer periphery of the positive electrode current collector; and an inner frame that is laid in a lattice pattern within the frame, wherein the positive electrode current collector is formed from a rolled material having a striped structure, the inner frame includes reinforcing bones, and the area of ​​a cross section perpendicular to the extension direction of the reinforcing bones is larger than the area of ​​a cross section perpendicular to the extension direction of the frame.

[0007] Another aspect of the present invention provides a positive electrode current collector for a lead-acid battery, which is a positive electrode current collector for use in a lead-acid battery, and includes a frame that forms an outer periphery of the positive electrode current collector, and an inner frame that is laid in a lattice pattern within the frame, wherein the positive electrode current collector is a punched lattice formed by punching out a rolled material, the inner frame includes reinforcing bones, and the area of ​​a cross section perpendicular to the extension direction of the reinforcing bones is larger than the area of ​​a cross section perpendicular to the extension direction of the frame. [Effects of the Invention]

[0008] According to the present disclosure, a decrease in the yield of the current collector can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a lead-acid battery according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a front view of a lead-acid battery. [Figure 3] FIG. [Figure 4] 2 is a vertical cross-sectional view (cross-sectional view taken along line AA in FIG. 1) of a lead-acid battery. [Figure 5] FIG. 2 is a front view of a first positive electrode current collector. [Figure 6] FIG. 3 is a cross-sectional view of a first positive electrode plate. [Figure 7] FIG. 2 is a front view of a second positive electrode current collector. [Figure 8] FIG. 10 is a front view of a third positive electrode current collector. [Figure 9] FIG. 10 is a front view of a fourth positive electrode current collector. [Figure 10]1A to 1C are diagrams illustrating the first half of a method for manufacturing a current collector. [Figure 11] 10A to 10C are diagrams illustrating the latter half of the method for producing a current collector. [Figure 12] 6 is an explanatory diagram showing a captured image of a cross section of the reinforcing bone in FIG. 5 (cross section at the position BB in FIG. 5). FIG. [Figure 13] 13 is an explanatory view showing an enlarged view of a part of the cross section of the reinforcing bone in FIG. 12. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Outline of this embodiment) (1) A positive electrode current collector according to one aspect of the present invention is a positive electrode current collector for use in a lead-acid battery, comprising a frame that forms an outer peripheral portion of the positive electrode current collector, and an inner frame that is laid in a lattice pattern within the frame, wherein the positive electrode current collector is formed from a rolled material having a striped structure, the inner frame includes reinforcing bones, and the area of ​​a cross section perpendicular to the extension direction of the reinforcing bones is larger than the area of ​​a cross section perpendicular to the extension direction of the frame.

[0011] (2) Another aspect of the present invention provides a positive electrode current collector for use in a lead-acid battery, the positive electrode current collector comprising a frame that forms the outer periphery of the positive electrode current collector, and an inner frame that is laid in a lattice pattern within the frame, the positive electrode current collector being a punched lattice formed by punching out a rolled material, the inner frame including a reinforcing frame, and the area of ​​a cross section perpendicular to the extension direction of the reinforcing frame being larger than the area of ​​a cross section perpendicular to the extension direction of the frame.

[0012] Because the cross-sectional area of ​​the reinforcing ribs perpendicular to the extension direction is larger than the cross-sectional area of ​​the frame ribs perpendicular to the extension direction, the strength of the reinforcing ribs is greater than the strength of the frame ribs. Furthermore, in the process of cutting each positive electrode current collector from the lattice roll, even if the width of the frame ribs becomes smaller and the strength of the frame ribs decreases, the width of the reinforcing ribs remains constant, and the reinforcing ribs reinforce the frame ribs, thereby ensuring the strength of the positive electrode current collector. As a result, positive electrode current collectors that are prone to battery performance degradation are less likely to be formed, and the yield of positive electrode current collectors can be improved without relying on the cutting accuracy of the frame ribs.

[0013] (3) The extension direction of the reinforcing bone is perpendicular to the rolling direction of the rolled material, the reinforcing bone has a striped structure, and the striped structure comprises a first outer peripheral portion extending in a planar direction along the outer peripheral surface of the reinforcing bone, and a second outer peripheral portion extending in a depth direction intersecting the outer peripheral surface of the reinforcing bone, and in a cross section perpendicular to the extension direction of the reinforcing bone, the length of the second outer peripheral portion may be 40% or less of the entire circumference of the cross section. Since corrosion is likely to progress along the cross section perpendicular to the rolling direction of the rolled sheet, a shorter length of the second outer periphery is preferable from the viewpoint of suppressing the progression of corrosion. However, because the cross-sectional area of ​​the reinforcing frame is larger than that of the frame, the exposed area of ​​the cross section perpendicular to the rolling direction of the rolled sheet increases, which tends to make corrosion of the reinforcing frame more likely to progress. Therefore, by further setting the length of the second outer periphery of the cross section of the reinforcing frame to 40% or less of the entire circumference of the cross section, the corrosion resistance of the reinforcing frame can be effectively improved.

[0014] (4) The reinforcing ribs may be disposed adjacent to the frame ribs. Since the reinforcing ribs are arranged adjacent to the frame ribs, the frame ribs can be easily reinforced by the reinforcing ribs.

[0015] (5) The frame has a rectangular shape overall and comprises a pair of vertical frame bones extending vertically and a pair of horizontal frame bones extending horizontally, with ears protruding from one of the horizontal frame bones to the outside of the frame bones, and the inner frame comprises a current collecting bone that connects the portion of one of the horizontal frame bones where the ears are formed to the other horizontal frame bone, and the reinforcing bone located between one of the vertical frame bones and the current collecting bone may be positioned closer to the vertical frame bones than the current collecting bones. Since the reinforcing ribs are arranged closer to one of the vertical frame ribs than the current collecting ribs, the reinforcing ribs can more easily reinforce the one of the vertical frame ribs.

[0016] (6) The reinforcing ribs may be arranged adjacent to the vertical frame ribs. Since the reinforcing ribs are arranged adjacent to the vertical frame ribs, the vertical frame ribs can be easily reinforced by the reinforcing ribs.

[0017] (7) The thickness of the positive electrode current collector may be 2.0 mm or less. In the case of a positive electrode current collector formed from rolled material, corrosion tends to progress more uniformly than in a positive electrode current collector formed by casting. Typically, as the thickness of a positive electrode current collector decreases, the frame becomes thinner or disappears during overcharge, making the positive electrode current collector more susceptible to elongation and deformation. However, by including reinforcing bones in the inner bone, even if the frame becomes thinner or disappears during overcharge, the reinforcing bones act as frame bones, thereby suppressing elongation and deformation of the positive electrode current collector. Furthermore, as the thickness of a positive electrode current collector decreases, the cutting accuracy of the frame tends to decrease during the process of cutting each positive electrode current collector from the lattice roll. However, as described above, the reinforcing bones make it less susceptible to the influence of the cutting accuracy of the frame bones, which is preferable.

[0018] (8) One aspect of the present invention provides a method for manufacturing a current collector for a lead-acid battery, the method including: a punching step of forming a current collector group by punching a rolled material made of lead or a lead alloy; and a cutting step of cutting the current collector group to individually cut out a plurality of current collectors, wherein the current collector comprises a frame that forms an outer periphery of the current collector and an inner frame that is laid in a lattice pattern within the frame, the inner frame including reinforcing bones, and the punching step may involve punching the rolled material so that the reinforcing bones extend in a direction perpendicular to the rolling direction of the rolled material.

[0019] In the process of cutting the current collector from the grid roll, even if the width of the frame becomes smaller and the strength of the frame decreases, the width of the reinforcing ribs remains constant, and the strength of the current collector is ensured by the reinforcing ribs reinforcing the frame. As a result, it is less likely that a current collector that is prone to degrading battery performance will be formed, and the yield of the current collector can be improved without relying on the cutting accuracy of the frame.

[0020] <Embodiment> An embodiment of the present disclosure will be described with reference to FIGS.

[0021] 1. Structure of lead-acid battery 10 The lead-acid battery 10 is for use in a vehicle such as an automobile, and is installed, for example, in the engine compartment or luggage space of the vehicle to supply power to an engine starting device and various vehicle loads. As shown in FIGS. 1 to 4 , the lead-acid battery 10 includes a battery case 20, a plate assembly 30, and a cover member 50 having a pair of terminal portions 60P, 60N. In the following description, the direction in which the terminal portions 60P, 60N are arranged is referred to as the X direction, and the direction perpendicular to the direction in which the terminal portions 60P, 60N are arranged (the front-to-rear direction of the battery case 20) is referred to as the Z direction. The side of the Z direction on which the terminal portions 60P, 60N are provided is referred to as the "front side," and the opposite side is referred to as the "rear side." The height direction (vertical direction) of the battery case 20 is referred to as the Y direction.

[0022] The battery case 20 is made of synthetic resin. The battery case 20 has four outer walls 21A to 21D and a bottom wall 22, and is box-shaped with an open top. As shown in FIG. 3, the interior of the battery case 20 is divided into a plurality of cell chambers 25 by partition walls 23. Six cell chambers 25 are provided in the width direction of the battery case 20 (the X direction in FIG. 3), and each cell chamber 25 contains a plate assembly 30 together with a flowable electrolyte.

[0023] As shown in Fig. 4, the electrode plate group 30 is composed of a positive electrode plate 30P, a negative electrode plate 30N, and a separator 40 that separates the positive electrode plates 30P, 30N, and is arranged in the arrangement direction (X direction) of the cell chambers 25. The positive electrode plate 30P includes a positive electrode current collector and a positive electrode active material 80 (see Fig. 6), and the negative electrode plate 30N includes a negative electrode current collector (not shown) and a negative electrode active material (not shown). The main component of the positive electrode active material 80 is lead dioxide, and the main component of the negative electrode active material is lead.

[0024] The positive electrode current collector is a so-called punched grid, and is obtained by punching and cutting a rolled sheet made of a lead alloy. The manufacturing method of the positive electrode current collector will be described in detail later. In this embodiment, the positive electrode current collector is exemplified by a first positive electrode current collector 32 shown in FIG. 5, a second positive electrode current collector 200 shown in FIG. 7, a third positive electrode current collector 300 shown in FIG. 8, and a fourth positive electrode current collector 400 shown in FIG. 9, but is not limited to these.

[0025] As shown in Fig. 5, the first positive electrode current collector 32 includes a frame 33 that forms the outer periphery of the first positive electrode current collector 32, and inner frames 34 that are arranged in a lattice pattern within the frame 33. Both ends of each inner frame 34 are connected to the frame 33. The frame 33 has a rectangular shape overall and includes a pair of left and right vertical frame frames 33A that extend vertically, and a pair of upper and lower horizontal frame frames 33B that extend horizontally. The inner frame 34 includes a plurality of vertical inner frames 34A that extend vertically within the frame 33, and a plurality of horizontal inner frames 34B that extend horizontally.

[0026] The negative electrode current collector is a so-called expanded grid, obtained by stretching a lead alloy sheet with staggered slits. The negative electrode current collector differs in shape from the first positive electrode current collector 32 in that it does not have bones on either side. The negative electrode current collector is not limited to an expanded grid, and may be a stamped grid or a cast grid.

[0027] The upper horizontal frame 33B of each electrode plate 30P, 30N has ears 36P, 36N that protrude outside the frame 33. The ears 36P, 36N are provided to connect electrode plates 30P, 30N of the same polarity within each cell chamber 25 via straps 37P, 37N.

[0028] The straps 37P, 37N are, for example, plate-shaped and long in the X direction, and one strap is provided for each positive electrode and one for each negative electrode. As shown in Fig. 4, each strap 37P, 37N is located above the electrode plate group 30. The positive electrode strap 37P connects the positive electrode plates 30P of the electrode plate group 30 via the tabs 36P, and the negative electrode strap 37N connects the negative electrode plates 30N of the electrode plate group 30 via the tabs 36N.

[0029] The separator 40 is made of a microporous polyolefin (polyethylene in this embodiment) sheet. The negative electrode plates 30N are housed inside the separator 40, and the negative electrode plates 30N and positive electrode plates 30P housed inside the separator 40 are arranged alternately.

[0030] 1, the cover member 50 is made of synthetic resin and includes a base 51 that seals the top surface of the battery case 20, and an outer peripheral wall 57 formed along the outer peripheral edge of the base 51. The outer peripheral wall 57 extends downward from the outer peripheral edge of the base 51.

[0031] A positive terminal portion 60P and a negative terminal portion 60N are provided on both sides of the front end of the base portion 51. The structures of the positive terminal portion 60P and the negative terminal portion 60N are the same, so the structure of the negative terminal portion 60N will be described below as an example.

[0032] As shown in Fig. 4, the negative terminal portion 60N includes a bushing 61 and a pole 65. The bushing 61 is made of a metal such as a lead alloy and has a hollow cylindrical shape. The bushing 61 passes through a cylindrical mounting portion 53 that is integrally formed with the base portion 51 of the cover member 50, and an upper half of the bushing 61 protrudes upward from the upper surface of the base portion 51. The upper half of the bushing 61 that is exposed from the upper surface of the base portion 51 is a terminal connection portion, to which a connection terminal (not shown), such as a harness terminal, is attached.

[0033] The cover member 50 is molded integrally by pouring resin into a mold in which the bushing 61 is inserted, so that the mounting portion 53 is integrated with the bushing 61 and covers the lower outer periphery of the bushing 61 without any gaps.

[0034] The pole 65 is made of a metal such as a lead alloy and has a cylindrical shape. The pole 65 is inserted into the bushing 61 from below. An upper end 65A of the pole 65 is joined to the bushing 61 by welding, and a base end 65B is joined to the strap 37N of the electrode plate pack 30.

[0035] 1, a protrusion 70 is provided on the base 51. The protrusion 70 is provided on substantially the entire rear side of the lid member 50 and on the center of the front side of the lid member 50. A portion of the protrusion 70 is provided between the pair of terminal portions 60P, 60N and protrudes in the height direction (Y direction) beyond the pair of terminal portions 60P, 60N. By doing so, for example, even if a metal bar or the like is placed on the top of the battery, the metal bar will not come into contact with the upper surfaces of the terminal portions 60P, 60N at the same time, and therefore, it is possible to prevent a short circuit between the pair of terminal portions 60P, 60N.

[0036] 2. Structure of the first positive electrode current collector 32 The first positive electrode current collector 32 is formed from a rolled material RM (see FIG. 10) having a striped structure. That is, the first positive electrode current collector 32 is a punched lattice obtained by punching the rolled material RM. As shown in FIG. 5, the inner ribs 34 of the first positive electrode current collector 32 include reinforcing ribs 35. Of the multiple vertical inner ribs 34A, the vertical inner rib 34A adjacent to the vertical frame rib 33A serves as the reinforcing rib 35. FIG. 6 is a cross-sectional view of the positive electrode plate 30P taken at position BB in FIG. 5. As shown in FIG. 6, the area of ​​a cross section perpendicular to the extension direction of the reinforcing rib 35 is larger than the area of ​​a cross section perpendicular to the extension direction of the vertical frame rib 33A.

[0037] The first positive electrode current collector 32 has the following problems. Problem 1. The plurality of first positive electrode current collectors 32 formed by punching the rolled material RM are formed into a lattice roll LR, and then each first positive electrode current collector 32 is cut out from the lattice roll LR. The vertical frame 33A is easily deformed by impacts received during handling in the process of cutting out each first positive electrode current collector 32 from the lattice roll LR and in the process of transporting the cut-out first positive electrode current collectors 32.

[0038] Problem 2: When cutting each first positive electrode current collector 32 from the lattice roll LR, the cutting position is the boundary between the vertical frame 33A of each of the two adjacent lattices. At this time, it is preferable to cut the vertical frame 33A so that the width of each vertical frame 33A is uniform. However, if the cutting accuracy is low, the width of the vertical frame 33A will vary, which is one of the causes of a decrease in the yield of the first positive electrode current collector 32.

[0039] Problem 3: In particular, the frame 33 is prone to direct contact with sulfuric acid. When the frame 33 is corroded by sulfuric acid, the frame 33 expands and the first positive electrode current collector 32 is deformed. As a result, the short-circuit resistance (high-temperature overcharge test performance) due to the deformation of the first positive electrode current collector 32 is reduced.

[0040] To address issue 1, shocks received during handling are preferentially absorbed by the vertical frame 33A, which has less strength than the reinforcing frame 35. As a result, shocks are less likely to be transmitted to the inner frame 34, including the reinforcing frame 35, and deformation of the first positive electrode current collector 32 is suppressed. Even if the vertical frame 33A deforms slightly, the reinforcing frame 35 replaces the vertical frame 33A, so the impact on battery performance is small and yield is improved. Furthermore, when a thin rolled material RM is used, the first positive electrode current collector 32 is more likely to deform, but the reinforcing frame 35 makes it easier to suppress deformation.

[0041] To address issue 2, in the process of cutting out each first positive electrode current collector 32 from the lattice roll LR, even if the width of the vertical frame 33A decreases and the strength of the vertical frame 33A decreases, the width of the reinforcing frame 35 remains constant, and the reinforcing frame 35 reinforces the vertical frame 33A, thereby ensuring the strength of the first positive electrode current collector 32. Here, because the reinforcing frame 35 is positioned adjacent to the vertical frame 33A, the reinforcing frame 35 easily reinforces the vertical frame 33A. As a result, first positive electrode current collectors 32 that are prone to degrading battery performance are less likely to be formed, and the yield of first positive electrode current collectors 32 can be improved without relying on the cutting accuracy of the vertical frame 33A.

[0042] For issue 3, even when the frame 33, which is located in a position prone to direct contact with sulfuric acid, expands due to corrosion, the reinforcing frame 35, although less effective than the frame 33, works to suppress deformation of the first positive electrode current collector 32. Furthermore, even after the frame 33 is removed, the reinforcing frame 35 remains without corroding much because it is located in a position prone to direct contact with sulfuric acid, and this can improve the short-circuit resistance (high-temperature overcharge test performance) due to deformation of the first positive electrode current collector 32.

[0043] The thickness of the first positive electrode current collector 32 is 2.0 mm or less. When the first positive electrode current collector 32 is formed from the rolled material RM, corrosion tends to progress more uniformly than when the first positive electrode current collector 32 is formed by casting. Typically, when the thickness of the first positive electrode current collector 32 is reduced, the frame ribs 33 disappear or thin during overcharge, making the first positive electrode current collector 32 more susceptible to elongation and deformation. However, by including the reinforcing ribs 35 in the inner ribs 34, the reinforcing ribs 35 function as the frame ribs 33 even when the frame ribs 33 disappear or thin during overcharge, thereby preventing elongation and deformation of the first positive electrode current collector 32. Furthermore, when the thickness of the first positive electrode current collector 32 is reduced, the cutting accuracy of the frame ribs 33 tends to decrease during the process of cutting each first positive electrode current collector 32 from the lattice roll LR. However, this is preferable because the reinforcing ribs 35 reduce the impact of the cutting accuracy of the frame ribs 33, as described above. If the thickness of the first positive electrode current collector 32 is too small, it becomes difficult to prevent a decrease in the cutting accuracy of the frame 33 by the reinforcing bones 35, and the frame 33 becomes more likely to deform during handling. Therefore, it is preferable that the thickness of the first positive electrode current collector 32 be 0.5 mm or more.

[0044] 3. Structure of the second positive electrode current collector 200 The structure of the second positive electrode current collector 200 will be described with reference to Fig. 7. The second positive electrode current collector 200 is a second positive electrode current collector 32 in which the arrangement of the reinforcing bones 35 is changed, and a description of the same components as those of the first positive electrode current collector 32 will be omitted. The same reference numerals will be used for the same components as those of the first positive electrode current collector 32.

[0045] The inner ribs 34 of the second positive electrode current collector 200 include reinforcing ribs 235. Of the multiple horizontal inner ribs 34B, the horizontal inner rib 34B adjacent to the horizontal frame rib 33B is the reinforcing rib 235. The area of ​​a cross section perpendicular to the extension direction of the reinforcing rib 235 is larger than the area of ​​a cross section perpendicular to the extension direction of the vertical frame rib 33A. The extension direction of the reinforcing rib 235 is parallel to the rolling direction of the rolled material RM.

[0046] It is known that if the tensile strength of the second positive electrode current collector 200 is low, it is susceptible to corrosion. Furthermore, it is known that the tensile strength of the rolled material RM is generally high in the rolling direction. As described above, the extension direction of the reinforcing bones 235 is parallel to the rolling direction of the rolled material RM, which increases the corrosion resistance of the reinforcing bones 235 and makes it easier to prevent the reinforcing bones 235 from elongating and deforming.

[0047] It is generally known that during overcharging, the vertical frame 33A disappears, but the horizontal frame 33B does not disappear because it is sufficiently thick. Also, even if there are reinforcing frame 235 extending in the Z direction, the vertical frame 33A disappears, but the reinforcing frame 235 does not replace the vertical frame 33A. However, because the reinforcing frame 235 has intersections with the multiple vertical inner frame 34A that remained unmelted, it is possible to suppress elongation in the Z direction by reinforcing the multiple vertical inner frame 34A that remained unmelted.

[0048] 4. Structure of the third positive electrode current collector 300 The structure of the third positive electrode current collector 300 will be described with reference to FIG. 8. The same reference numerals will be used for the same components as those of the first positive electrode current collector 32. The third positive electrode current collector 300 includes a frame 302 that forms the outer periphery of the third positive electrode current collector 300, and inner ribs that are arranged in a lattice pattern within the frame 302. The inner ribs include a plurality of vertical ribs 303 that extend linearly in the up-down direction within the frame 302, and a plurality of sub-ribs 304 that are formed at an angle within the frame 302. The vertical ribs 303 correspond to the vertical inner ribs of the present disclosure, and the sub-ribs 304 correspond to the horizontal inner ribs of the present disclosure.

[0049] The frame 302 has a rectangular shape overall, and includes a first side 302a with ears 36P protruding outside the frame, a second side 302b facing the first side 302a, and a third side 302c and a fourth side 302d substantially perpendicular to the first and second sides 302a and 302b. The third side 302c connects one end of the first side 302a to one end of the second side 302b. The fourth side 302d connects the other end of the first side 302a to the other end of the second side 302b.

[0050] The multiple vertical bones 303 include one or more main bones 303X extending downward from directly below the connection portion between the first side portion 302a and the ear portion 36P. The main bone 303X connects the portion of the first side portion 302a where the ear portion 36P is formed to the second side portion 302b. The multiple vertical bones 303 on both the left and right sides of the main bone 303X are arranged at equal intervals in the left-right direction (the extension direction of the first side portion 302a). The main bones 303X correspond to the current collecting bones of the present disclosure.

[0051] The main bones 303X extend linearly and substantially perpendicular to the first side 302a and the second side 302b of the frame bone 302. The area of ​​a cross section perpendicular to the extension direction of the main bones 303X is larger than the area of ​​a cross section perpendicular to the extension direction of the vertical bones 303 other than the main bones 303X. This allows for efficient current collection while reducing the amount of electrode plate material used by making the portion with a high amount of electricity near the ear portions 36P, which are the current collecting portions, thicker and making the portion with a low amount of electricity thinner.

[0052] The multiple sub-bones 304 include a sub-bone 304N located on the left side of the main bone 303X and extending diagonally downward, and a sub-bone 304M located on the right side of the main bone 303X and extending diagonally downward. The upper end of the sub-bone 304N is connected to the main bone 303X or the vertical bone 303, and the lower end of the sub-bone 304N is connected to the third side portion 302c or the vertical bone 303. The upper end of the sub-bone 304M is connected to the main bone 303X or the vertical bone 303, and the lower end of the sub-bone 304N is connected to the fourth side portion 302d or the vertical bone 303.

[0053] The sub-rib 304N extends linearly without bending toward the third side portion 302c from the connection portion with the main rib 303X or the vertical rib 303. The inclination angle of the sub-rib 304N with respect to the main rib 303X is, for example, 75 degrees.

[0054] On the other hand, the sub-bone 304M is bent once at the position where it intersects with the vertical bone 303. The sub-bone 304M is then divided into two divided bones at the bending point. The two divided bones include a first divided bone 304a that is located close to the main bone 303X, and a second divided bone 304b that is connected to the first divided bone 304a and located far from the main bone 303X.

[0055] The first divided bone 304a is arranged so that its inclination angle with respect to the main bone 303X is, for example, 75 degrees, and the second divided bone 304b is arranged so that its inclination angle with respect to the main bone 303X is, for example, 90 degrees. Therefore, these two divided bones 304a, 304b are inclined so that their inclination angle with respect to the main bone 303X does not exceed 90 degrees, and the inclination angle of the second divided bone 304b is set larger than the inclination angle of the first divided bone 304a. Note that the inclination angles of the divided bones 304a, 304b with respect to the main bone 303X can be changed as appropriate as long as they do not exceed 90 degrees.

[0056] Of the multiple vertical ribs 303, a pair of vertical ribs 303 adjacent to the third side portion 302c and the fourth side portion 302d are reinforcing ribs 335. The area of ​​a cross section perpendicular to the extension direction of the left reinforcing rib 335 is larger than the area of ​​a cross section perpendicular to the extension direction of the third side portion 302c, and the area of ​​a cross section perpendicular to the extension direction of the right reinforcing rib 335 is larger than the area of ​​a cross section perpendicular to the extension direction of the fourth side portion 302d. The left reinforcing rib 335 is arranged closer to the third side portion 302c than the main rib 303X, and the right reinforcing rib 335 is arranged closer to the fourth side portion 302d than the main rib 303X.

[0057] Both ends of the reinforcing bone 335 must be connected to both the first side portion 302a and the second side portion 302b. Therefore, a vertical bone 303 having one end connected to the first side portion 302a or the second side portion 302b and the other end connected to a sub-bone 304 (inner horizontal bone) is not a reinforcing bone 335.

[0058] Because the left reinforcing rib 335 is disposed closer to the third side 302c than the main rib 303X, the third side 302c can be more easily reinforced by the left reinforcing rib 335. Moreover, because the right reinforcing rib 335 is disposed closer to the fourth side 302d than the main rib 303X, the right reinforcing rib 335 can be more easily reinforced by the fourth side 302d.

[0059] 5. Structure of the fourth positive electrode current collector 400 The structure of the fourth positive electrode current collector 400 will be described with reference to Fig. 9. The fourth positive electrode current collector 400 is obtained by changing the arrangement of the reinforcing ribs 335 of the third positive electrode current collector 300, i.e., by replacing the sub-ribs 304 with reinforcing ribs 435, and a description of the same components as those of the third positive electrode current collector 300 will be omitted. The same reference numerals will be used for the same components as those of the third positive electrode current collector 300.

[0060] The reinforcing bones 435 of the fourth positive electrode current collector 400 are the sub-bones 304 adjacent to the first side portion 302a and the second side portion 302b among the multiple sub-bones 304. However, only the sub-bones 304 extending from the third side portion 302c to the fourth side portion 302d function as reinforcing bones 435. Therefore, even if a sub-bones 304 is adjacent to the first side portion 302a and the second side portion 302b, if one end of the sub-bones 304 is connected to the third side portion 302c or the fourth side portion 302d and the other end is connected to the vertical bone 303, the sub-bones 304 are not reinforcing bones 435. Therefore, both ends of the reinforcing bones 435 are connected to both the third side portion 302c and the fourth side portion 302d. The extension direction of the reinforcing bones 435 is substantially parallel to the rolling direction of the rolled material RM.

[0061] If the tensile strength of a current collector is low, it tends to be susceptible to corrosion, and the tensile strength is greater in the rolling direction. Therefore, by forming the reinforcing bones 435 so that they extend in a direction parallel to the rolling direction of the rolled material RM, as in the fourth positive electrode current collector 400, corrosion resistance is more easily achieved.

[0062] Fig. 12 is an explanatory diagram showing an image of the XZ cross section of the reinforcing bone 35 taken at the position BB in Fig. 5. Fig. 13 is an explanatory diagram showing an enlarged portion of the XZ cross section of the reinforcing bone 35 in Fig. 12. Hereinafter, for each of the reinforcing bones 35 and the reinforcing bone 235 (see Fig. 7), the length in the direction (X-axis direction) substantially perpendicular to the positive electrode current collectors 32, 200 will be referred to as the "thickness of each reinforcing bone 35, 235." Furthermore, for the reinforcing bone 35, the direction (Z-axis direction) substantially parallel to the positive electrode current collectors 32, 200 and substantially perpendicular to the vertical inner bones 410 will be referred to as the "width direction of the reinforcing bone 35," and the length of the reinforcing bone 35 in the width direction will be referred to as the "width of the reinforcing bone 35." Furthermore, with regard to the reinforcing bone 235, the direction (Y-axis direction) that is approximately parallel to the positive electrode current collector 200 and approximately perpendicular to the reinforcing bone 235 is referred to as the "width direction of the reinforcing bone 235," and the length of the reinforcing bone 235 in the width direction is referred to as the "width of the reinforcing bone 235."

[0063] 12, in an XZ cross section substantially perpendicular to the extension direction (Y-axis direction) of the reinforcing bone 35, the outer shape of the reinforcing bone 35 is such that the thickness at both ends in the width direction (Z-axis direction) of the reinforcing bone 35 is thinner than the thickness at the center. Specifically, the outer shape of the reinforcing bone 35 in the XZ cross section is substantially octagonal. In this embodiment, the outer shape and size of the reinforcing bone 35 in the XZ cross section are substantially constant over the entire length of the reinforcing bone 35.

[0064] The reinforcing bone 35 has a striped structure. As shown in FIG. 12 , the outer peripheral surface 350 of the reinforcing bone 35 includes a pair of first outer peripheral portions 351 and a pair of second outer peripheral portions 352. The first outer peripheral portions 351 are located on both sides of the reinforcing bone 35 in a direction (X-axis direction) substantially perpendicular to the positive electrode current collector 32. Each of the first outer peripheral portions 351 is a surface region in which the striped structure extends in a planar direction along the outer peripheral surface 350 of the reinforcing bone 35 (hereinafter simply referred to as the "planar direction of the reinforcing bone 35"). In this embodiment, the pair of first outer peripheral portions 351 is a surface region of the outer peripheral surface 350 of the reinforcing bone 35 excluding the pair of second outer peripheral portions 352. Meanwhile, the second outer peripheral portions 352 are located on both sides of the reinforcing bone 35 in the width direction (Z-axis direction) of the positive electrode current collector 32. The second outer peripheral portion 352 is a surface region in which the striped structure extends in a depth direction (hereinafter simply referred to as "depth direction of the reinforcing bone 35") intersecting the outer peripheral surface 350 of the reinforcing bone 35. In other words, the pair of second outer peripheral portions 352 are surface regions located at both ends in the width direction (Z-axis direction) of the reinforcing bone 35, and are surface regions of the surface region of the reinforcing bone 35 that are not the first outer peripheral portion 351.

[0065] 12 and 13 is a rolled structure formed by, for example, elongating crystal grains by rolling. Therefore, in the first outer peripheral portion 351, the crystal grain boundaries of the striped structure extend longer in the direction along the first outer peripheral portion 351 (Z-axis direction) than in the depth direction of the reinforcing rib 35 (X-axis direction in FIGS. 12 and 13).

[0066] Similarly, in the second outer peripheral portion 352, the grain boundaries extend longer in a direction intersecting the second outer peripheral portion 352 (the X-axis direction) than in a direction along the second outer peripheral portion 352. When the positive electrode current collector 32 of this embodiment is produced by punching a rolled sheet, the layer above the punching direction may be rolled in and plastically deformed during punching, exposing a striped structure extending in the plane direction of the reinforcing bones 35 in the surface layer of the second outer peripheral portion 352. Even in such a case, a striped structure extending in the depth direction (in other words, a metal structure in which the grain boundaries extend in the depth direction of the reinforcing bones 35) is formed at a position at a certain depth or more from the surface. In this embodiment, the surface region of the reinforcing bones 35 where the striped structure extending in the depth direction of the reinforcing bones 35 is formed at a position at a certain depth or more from the surface is also considered to be the second outer peripheral portion 352.

[0067] The first outer periphery 351 and the second outer periphery 352 can be distinguished as follows. As shown in Fig. 12, a layered metal structure is observed in a predetermined cross section of the reinforcing bone 35. Here, a portion in the cross section where the layered structure along the surface direction of the reinforcing bone 35 can be observed is defined as the first outer periphery 351. A portion near the outer periphery 350 of the reinforcing bone 35 where the layered structure bends from the depth direction of the reinforcing bone 35 to the surface direction of the reinforcing bone 35, or a portion in the outer periphery 350 of the reinforcing bone 35 where the layered structure cannot be observed is defined as the second outer periphery 352.

[0068] In the reinforcing bone 35 of this embodiment, the total length of the pair of first outer peripheral portions 351 is longer than the total length of the pair of second outer peripheral portions 352 in the XZ cross section over the entire length of the reinforcing bone 35. In other words, in the XZ cross section, the ratio of the total length of the first outer peripheral portions 351 to the entire circumferential length of the reinforcing bone 35 is higher than the ratio of the total length of the second outer peripheral portions 352 to the entire circumferential length of the reinforcing bone 35. That is, on the outer circumferential surface 350 of the reinforcing bone 35, the portion where the striped texture extends in the surface direction of the reinforcing bone 35 is wider than the portion where the striped texture extends in the depth direction of the reinforcing bone 35. Note that, in the XZ cross section, the length of the second outer peripheral portion 352 is preferably 40% or less of the entire circumference of the XZ cross section of the reinforcing bone 35, and more preferably 30% or less of the entire circumference of the XZ cross section of the reinforcing bone 35.

[0069] In an XY cross section substantially perpendicular to the extension direction (Z-axis direction) of the reinforcing bone 235, the outer shape of the reinforcing bone 235 is substantially the same as the outer shape of the reinforcing bone 35 in the XZ cross section, and the thickness of both ends of the reinforcing bone 235 in the width direction (Y-axis direction) is thinner than the thickness of the central part. In this embodiment, the outer shape of the reinforcing bone 235 in the XY cross section is substantially the same over the entire length. The outer peripheral surface of the reinforcing bone 235 has a striped texture that extends mainly in the plane direction of the reinforcing bone 35 overall.

[0070] 6. Current collector manufacturing method A method for manufacturing a current collector will be described with reference to Figures 10 and 11. Here, a method for manufacturing third positive electrode current collector 300 is illustrated as an example, but the same applies to other current collectors 32, 200, and 400. In addition, the method for manufacturing a current collector is not limited to the following method.

[0071] As shown in Fig. 10(A), a sheet-like rolled material RM extending in the rolling direction MD is prepared, and as shown in Fig. 10(B), punching is continuously performed to obtain a lattice roll LR (punching process). The lattice roll LR is a current collector group CG in which multiple current collectors C are lined up in a row in the rolling direction MD and arranged in two rows with the ear portions 36P facing inward.

[0072] The current collector groups CG in each row are connected to one another via the tabs 36P, and as shown in FIG. 10(C), a cut CL is made between a pair of current collectors C adjacent to one another in the rolling direction MD, thereby cutting out the current collector group CG into pairs of current collectors C. At this point, a pair of current collectors C adjacent to one another in a direction perpendicular to the rolling direction MD are connected via the pair of tabs 36P. Subsequently, as shown in FIG. 11(D), a cut CL is made at the tip of the tab 36P, thereby cutting out the pair of current collectors C individually (cutting out process). In this way, the current collector C (third positive electrode current collector 300) shown in FIG. 11(E) is obtained.

[0073] 7. Rolling direction of rolled material RM The rolling direction of the rolled material RM can be identified by the following method. -1. After removing the active material from the disassembled positive electrode plate, cut out the frame so that the cross section is perpendicular to the extension direction of the frame. To improve measurement accuracy, it is preferable to make the frame as thick as possible. Also, since there is a high possibility that the rolling structure will have recrystallized at the edge of the lattice due to the heat generated during welding, use a frame located away from the edge for measurement. -2. The vertical (Y direction) and horizontal (Z direction) sides of the frame are cut out and fixed in place using resin or similar, after which the cut cross sections are polished with sandpaper of #200 or higher. -3. Using X-ray diffraction (hereinafter referred to as "XRD"), the diffraction peaks of the cross section polished in -2 are measured. The peaks are analyzed by the intensity resolution / FP method to measure the crystallite size of the Pb crystals contained in the rolled material RM. The measurement and analysis conditions are as follows. Equipment used: Rigaku Smart Lab fully automated multipurpose X-ray diffraction instrument (horizontal goniometer θ-θ type, Cu-Kα radiation) Analysis software: RIGAKU's integrated powder X-ray analysis software PDXL2 Applied voltage: 40kV ·Applied current: 30mA · Crystallite size identification method: Strength decomposition / Fundamental parameter (FP) method The surface with the smallest crystallite size is the surface parallel to the rolling direction. For example, if the crystallite size of the vertical side is less than the crystallite size of the horizontal side, the material was rolled in the vertical direction.

[0074] <Other embodiments> The present disclosure is not limited to the embodiments described above and illustrated in the drawings, but is intended to include all modifications within the scope and meaning equivalent to the claims. The technical scope of the present disclosure also includes, for example, the following embodiments.

[0075] The reinforcing ribs do not have to be located adjacent to the frame ribs.

[0076] The extension direction of the reinforcing bone may be perpendicular to the rolling direction of the rolled material.

[0077] · The inner bone does not have to have a main bone (collecting bone).

[0078] The thickness of the positive electrode current collector may be greater than 1.5 mm.

[0079] The reinforcing frame may be provided closer to the frame than the midpoint between the current collecting frame and the frame. [Explanation of symbols]

[0080] 10 Lead acid battery 20 Battery case 21A, 21B, 21C, 21D exterior walls 22 Bottom wall 23 Bulkhead 25 Cell Room 30 plate group 30P positive electrode plate 30N negative electrode plate 32 First positive electrode current collector 33 Frame 33A Vertical frame 33B Horizontal frame bone 34 Inner bone 34A Longitudinal bone 34B Lateral bone 35 Reinforcement bone 350 Outer surface of reinforcing bone 351 First Outer Circle 352 Second outer periphery 36P,36N ears 37P, 37N Strap 40 Separator 50 Lid member 51 Base 53 Mounting part 57 Outer wall 60P, 60N terminal 61 Bushing 65 Pole Pillar 65A Upper end 65B Base end 70 Protrusion 80 Cathode active material 200 Second positive electrode current collector 235 Reinforcement bone 300 Third positive electrode current collector 302 Frame 302a 1st side 302b 2nd side 302c 3rd side 302d 4th side 303 Longitudinal bone (internal bone) 303X Main bone 304, 304M, 304N Sub-bone (inner bone) 304a 1st division bone 304b 2nd split bone 335 Reinforcement bone 400 4th positive electrode current collector 435 Reinforcement bone C Current collector CG current collector group CL notch MD rolling direction LR lattice roll RM Rolled Material

Claims

1. A positive electrode current collector for use in a lead-acid battery, a frame that forms an outer periphery of the positive electrode current collector; and an inner frame that is laid in a lattice pattern within the frame frame, the positive electrode current collector is formed of a rolled material having a striped texture, The inner bone includes a reinforcing bone, a cross-sectional area of ​​the reinforcing rib perpendicular to the extension direction thereof is larger than a cross-sectional area of ​​the frame rib perpendicular to the extension direction thereof;

2. A positive electrode current collector for use in a lead-acid battery, a frame that forms an outer periphery of the positive electrode current collector; and an inner frame that is laid in a lattice pattern within the frame frame, The positive electrode current collector is a punched grid obtained by punching a rolled material, The inner bone includes a reinforcing bone, a cross-sectional area of ​​the reinforcing rib perpendicular to the extension direction thereof is larger than a cross-sectional area of ​​the frame rib perpendicular to the extension direction thereof;

3. the extension direction of the reinforcing bone is perpendicular to the rolling direction of the rolled material; The reinforcing bone has a striped structure, the striped structure comprises a first outer peripheral portion extending in a planar direction along the outer peripheral surface of the reinforcing bone, and a second outer peripheral portion extending in a depth direction intersecting the outer peripheral surface of the reinforcing bone, 3. The positive electrode current collector for a lead-acid battery according to claim 1, wherein in a cross section perpendicular to an extension direction of the reinforcing rib, a length of the second outer periphery is 40% or less of an entire circumference of the cross section.

4. 3. The positive electrode current collector for a lead-acid battery according to claim 1, wherein the reinforcing ribs are disposed adjacent to the frame ribs.

5. The frame has a rectangular shape as a whole and includes a pair of vertical frame bones extending in the vertical direction and a pair of horizontal frame bones extending in the horizontal direction, A lug portion is provided that protrudes from one of the horizontal frame bones to the outside of the frame bones, The inner frame includes a current collecting bone that connects a portion of one of the horizontal frame bones where the ear portion is formed to the other horizontal frame bone, 3. The positive electrode current collector for a lead-acid battery according to claim 1, wherein the reinforcing bone located between one of the vertical frame bones and the current collecting bone is arranged at a position closer to the one of the vertical frame bones than the current collecting bone.

6. The positive electrode current collector for a lead-acid battery according to claim 5 , wherein the reinforcing frame is disposed adjacent to the vertical frame.

7. 3. The positive electrode current collector for a lead acid battery according to claim 1, wherein the positive electrode current collector has a thickness of 2.0 mm or less.

8. A method for manufacturing a current collector for a lead-acid battery, the method comprising: a punching step of forming a current collector group by punching a rolled material made of lead or a lead alloy; and a cutting step of cutting the current collector group to individually cut out a plurality of current collectors, the current collector includes a frame that forms an outer periphery of the current collector, and an inner frame that is laid in a lattice pattern within the frame, The inner bone includes a reinforcing bone, In the punching step, the rolled material is punched so that the reinforcing ribs extend in a direction perpendicular to a rolling direction of the rolled material.

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