Methods for manufacturing lead-acid batteries.

Abstract

DEPCT64 The method of manufacturing lead-acid batteries with a group of electrodes consisting of multiple positive electrode plates and... Multiple negative electrode plates are stacked within it, relying on a separator, which includes processing the separator itself. It is bag-shaped, with two regions facing each other; the processing step of the separator is to shape it into a bag. This will include creating a joint section that contains at least part of the first region and at least part of the second region. One part of the first ridge will be arranged in the first area, and one part of the second ridge will be arranged. It occurs in the second area, and the joint creation process will include making areas one and two. They are positioned towards each other so that at least one of the first ribs and at least one of the second ribs intersect at the same section. Joint -----------------------------------------------------------

Description

Method for manufacturing a lead-acid battery

[0001] The present invention relates to a method for manufacturing a lead-acid battery.

[0002] Lead-acid batteries are used in various applications, including in-vehicle and industrial applications. A lead-acid battery includes a negative electrode plate, a positive electrode plate, a separator interposed between the negative electrode plate and the positive electrode plate, and an electrolyte. Generally, an aqueous sulfuric acid solution is used as the electrolyte.

[0003] Patent Document 1 discloses an example in which a negative electrode plate is housed in a bag-shaped polyethylene separator, and the bag-shaped separator has ribs on the negative electrode plate side. In this example, the ribs are formed inside the bag-shaped separator.

[0004] When forming the separator into a bag shape, generally, the separator is bent into a U shape and both side edges are joined. Examples of the method for joining both side edges include methods using gear seal, heat seal, and ultrasonic seal, or methods using an adhesive or an adhesive tape (see, for example, Patent Document 2).

[0005] JP-A-2015-22796, JP-A-2009-245901

[0006] In the manufacture of the bag-shaped separator having ribs formed inside, as exemplified in Patent Document 1, when joining both side edges of the separator, those having ribs formed on the joining surface can be used.

[0007] However, when overlapping separators having ribs formed on the joining surface and joining both side edges, sufficient joining strength may not be obtained depending on the arrangement of the ribs.

[0008] One aspect of the present invention relates to a method for manufacturing a lead-acid battery having an electrode plate group in which a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with a separator in between, the method comprising processing the separator into a bag shape having a first region and a second region facing each other, the processing of the separator into a bag shape comprising forming a joint portion including at least a part of the first region and at least a part of the second region, a plurality of first ribs provided in the first region, a plurality of second ribs provided in the second region, and the method for forming the joint comprising facing the first region and the second region such that at least one of the first ribs and at least one of the second ribs intersect at the joint portion.

[0009] According to this disclosure, the strength of the joint of a bag-shaped separator used in a lead-acid battery can be increased.

[0010] This is a schematic front view showing the appearance of a lead-acid battery separator used in a method for manufacturing a lead-acid battery according to one aspect of the present invention. This is a schematic diagram showing a separator sheet before it is processed into a bag shape. This is a schematic diagram showing the state of the inner ribs when the separator sheets are stacked. This is a schematic diagram showing a separator sheet before it is processed into a bag shape, showing another aspect of Figure 2. This is a schematic diagram showing a separator sheet before it is processed into a bag shape, showing another aspect of Figure 2. This is a schematic diagram showing a separator sheet before it is processed into a bag shape, showing another aspect of Figure 2. This is a perspective view showing a part of a lead-acid battery using a bag-shaped separator.

[0011] A method for manufacturing a lead-acid battery according to one aspect of the present invention is a method for manufacturing a lead-acid battery having an electrode plate group in which a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with a separator in between, and the method includes processing the separator into a bag shape having a first region and a second region that face each other. Processing the separator into a bag shape includes forming a joint that includes at least a part of the first region and at least a part of the second region. A plurality of first ribs are provided in the first region and a plurality of second ribs are provided in the second region. Forming the joint includes facing the first region and the second region such that at least one of the first ribs and at least one of the second ribs intersect at the joint.

[0012] According to the above aspect of the present invention, a joint is formed in a predetermined area (preferably the inner peripheral edge) provided within the first area and the second area, for closing the first and second areas together in a bag-like manner.

[0013] Specifically, for example, a separator sheet having a first region and a second region on the same main surface can be folded in half, and a joint can be formed by facing the first region and the second region opposite each other. In this case, by overlapping a single separator sheet in a U-shape, the folded portion becomes the lower end, joints are provided on the left end and the right end, and a bag-shaped separator with an opening at the upper end can be manufactured. However, a bag-shaped separator may also be manufactured by making the right end (or left end) of the separator sheet the folded portion and forming joints on the left end (or right end) and the lower end. Alternatively, a bag-shaped separator may be manufactured by laminating a first half sheet having a first region on its main surface and a second half sheet having a second region on its main surface, and facing the first region and the second region opposite each other. In this case, the two half sheets can be overlapped, and joints can be formed on the left end, the right end, and the lower end to manufacture a bag-shaped separator. Bag-shaped separators are used to house the positive or negative electrode plates of lead-acid batteries.

[0014] Here, in a bag-shaped separator, the direction in which the opening for inserting the positive or negative electrode plate is provided is defined as the upper side (vertical direction) of the separator, and the opposite side is defined as the lower side. Furthermore, when the upper and lower sides of the separator are defined in this way, the direction located to the left from the viewer's perspective is defined as the left side of the separator, and the direction located to the right from the viewer's perspective is defined as the right side of the separator.

[0015] Furthermore, a rib refers to a protruding portion that extends from one surface of the separator. It is provided to suppress adhesion between the separator and the electrode plate, and to prevent tearing due to oxidative degradation of the separator, and / or penetration short circuits. The ribs are provided on the surface of the separator in a predetermined pattern.

[0016] The external shape of the bag-shaped separator can be formed to be similar to the external shape of the first region. Preferably, the external shape of the first region is rectangular. In this case, the bag-shaped separator has an external shape that is approximately rectangular. By providing a joint in the vicinity of at least two sides constituting the rectangle, the separator sheet (or two half sheets) can be processed into a bag shape. The external shape of the bag-shaped separator is not limited to a rectangle, but may be any shape (for example, a polygon or an arc shape). The sides constituting the polygon do not need to be strictly straight lines, and may have curved or bent portions. For example, when a bag-shaped separator with an external shape that is approximately triangular is made by folding, the joint region may be provided on the end side corresponding to one side of the triangle.

[0017] The first and second regions constitute the mutually opposing inner surfaces of the bag-shaped separator. Preferably, the separator sheet or half-sheet has a joining region and an electrode plate region within the first and second regions. The joining region is a region that includes a joining portion that binds the first and second regions together in a bag-like shape, and is set to be a wider area than the joining portion, taking into consideration positioning margins related to the joining. Preferably, the joining region is provided on the end side of the separator sheet or half-sheet, and the peripheral region within a predetermined distance to the end can be designated as the joining region. In contrast, the electrode plate region is a region separated from the joining region and is the region that faces the positive or negative electrode plate when the positive or negative electrode plate is housed in the bag-shaped separator.

[0018] If the joining region is located on the end side of the separator sheet or half sheet, the joining portion should be provided so as to include that end. Alternatively, within the joining region, the joining portion may be formed by extending parallel to the contour of the end of the bag-shaped separator (i.e., the contour of the end of the separator sheet or half sheet), or it may be formed by extending with any contour shape different from the contour of the end of the bag-shaped separator.

[0019] Multiple first ribs are provided within the first region, and multiple second ribs are provided within the second region. The inner surfaces of the joined bag-shaped separator are referred to as the first surface and the second surface. In the joined bag-shaped separator, the first region lies on the first surface, and the second region lies on the second surface. The first ribs are formed in the electrode plate region within the first region on the first surface, thereby preventing either the positive or negative electrode plate from adhering closely to the first surface. Similarly, the second ribs are formed in the electrode plate region within the second region on the second surface, thereby preventing either the positive or negative electrode plate from adhering closely to the second surface. The first and second ribs provided in the electrode plate region suppress tearing and / or penetration short circuits due to oxidative degradation of the separator when the positive or negative electrode plate is housed inside. Hereafter, the first and second ribs will be collectively referred to as "internal ribs". Generally, the first and second ribs are arranged in a linear pattern such that multiple ribs are spaced parallel to adjacent ribs within a predetermined area.

[0020] The first rib and the second rib (internal rib) are also formed in the joining regions within the first and second regions. When internal ribs are formed in the joining regions, the first rib and the second rib may overlap when the first and second regions face each other to form a joint. However, depending on how they overlap, sufficient joint strength may not be obtained.

[0021] For example, during joint formation, the first and second regions may be superimposed such that the second rib in the second region's joint area fits into the groove between adjacent first ribs within the first region's joint area (or the first rib in the first region's joint area fits into the groove between adjacent second ribs within the second region's joint area). In this case, the joint strength is lower than when the first and second ribs overlap. In particular, the tendency for joint strength to decrease is greater when the joining method is a crimping method such as a gear seal. However, considering the positioning accuracy of the joint by the joining device, it is difficult to completely prevent the situation where the second rib fits into the groove of the first rib (or the first rib fits into the groove of the second rib), which contributes to variations in joint strength. As a result, variations occur in the performance of the lead-acid battery.

[0022] This is a common problem when manufacturing bag-shaped separators with internal ribs, regardless of whether welding or bonding is used. However, it is particularly pronounced in joining methods that compress the joint to a predetermined thickness, such as the gear seal method or heat welding method. In these methods, one of the ribs (the first or second) fits into the groove of the other rib, resulting in a thinner joint thickness than expected before compression. As a result, the compression ratio when compressing to the predetermined thickness decreases, which easily leads to a decrease in joint strength.

[0023] Therefore, one aspect of the present invention includes arranging the first region and the second region opposite each other when forming a joint, such that at least one of the first ribs and at least one of the second ribs intersect at the joint. By arranging the first region and the second region opposite each other so that the first ribs and the second ribs intersect depending on the arrangement of the internal ribs, it is possible to suppress other ribs from getting stuck in the grooves between adjacent ribs. By forming the joint in a state where rib getting stuck is suppressed, variations in the strength of the joint of the bag-shaped separator are reduced, and the joint strength can be maintained.

[0024] Here, "intersection" of the first rib and the second rib means that the first region and the second region face each other and the first rib and the second rib make contact at least at a point. The first rib and the second rib may also be in contact along a line or across a surface. Note that the number of points of contact is not limited to one. The linear pattern of the rib may be a straight line or a curve. It may also be a dotted line with part of the straight line or curve missing. A stripe-like pattern of multiple ribs, each composed of parallel straight lines, is preferable because it is easy to manufacture the ribs. The angle at which the first rib and the second rib intersect should preferably be 0.2° or more, more preferably 0.3° or more. A sufficient joint strength can be obtained if the intersection angle is 0.2° or more.

[0025] Depending on the method of forming the joint, it may be difficult to determine whether the first rib and the second rib intersect at the joint based on the state of the joint of the bag-shaped separator after manufacturing. In this case as well, it is possible to estimate whether the first rib and the second rib intersect at the joint from the arrangement of the first rib and the second rib in the region surrounding the joint. For example, if in the joint region the first rib and the second rib are each formed in a linear fashion at regular intervals, extending in a certain direction, it can be estimated that in the joint, the first rib and the second rib are similarly formed in a linear fashion extending in the same direction as the rib extension in the joint region, with the same rib spacing as in the joint region. In other words, it is possible to estimate the intersection of the first rib and the second rib by interpolating or extrapolating the rib pattern in the joint from the rib pattern in the region surrounding the joint.

[0026] As an arrangement pattern for the first and second ribs, for example, when considering a separator sheet in the shape of a quadrilateral (rectangle, trapezoid, or parallelogram) with substantially parallel opposite sides, a configuration can be adopted in which the first and second ribs both extend linearly in the same direction along the main surface of the separator sheet in at least the region within the first region where a joint is provided (joint region), and at least the region within the second region where a joint is provided (joint region). Note that the first and second ribs extending in the same direction along the main surface means that, before folding the separator sheet in half, when the first and second regions are on the same plane, the first and second ribs both extend in the same direction. The first and second ribs may both extend linearly along the main surface of the separator sheet in a direction substantially parallel to the opposite sides of the separator sheet. Alternatively, both the first and second ribs may be extended linearly along the main surface of the separator sheet in a direction substantially perpendicular to the opposite side of the separator sheet. Note that "parallel" or "perpendicular" to the opposite side does not mean that the extension direction of the ribs is strictly parallel or perpendicular in a mathematical sense. In these cases, when folding the separator sheet in half and facing the first and second regions, the folding axis is a direction inclined from the direction perpendicular to the opposite side. For example, if the separator sheet is a rectangle with the opposite side as the longer side, the separator sheet is folded in half with the axis inclined from the direction of the shorter side of the separator sheet. By shifting the axis of folding the separator sheet from the axis of symmetry, when the first and second regions are facing each other, the second rib can be extended linearly in an oblique direction different from the extension direction of the first rib.

[0027] Furthermore, as an arrangement pattern for the first and second ribs, for example, a configuration can be adopted in which, in the region within the first region of the separator sheet where a joint is provided (joint region), and in the region within the second region where a joint is provided (joint region), the first and second ribs extend linearly along the main surface of the separator sheet in the same direction, but in a direction inclined from a direction parallel to the opposite side of the separator sheet. In this case, when folding the separator sheet in half and facing the first and second regions, the separator sheet may be folded in half with the direction perpendicular to the opposite side as the axis. For example, if the separator sheet is a rectangle with the opposite side as the longer side, the separator sheet may be folded in half with the direction of the shorter side as the axis. Since the first and second ribs extend at an angle parallel to the opposite sides, when the first and second regions are placed facing each other, the second rib can be extended linearly in a direction oblique to the extension direction of the first rib.

[0028] By aligning the first and second regions with the second rib extending in a direction inclined relative to the first rib, the intersection of the first and second ribs becomes more likely to occur at the joint. This reduces variations in joint strength and allows for the maintenance of joint strength.

[0029] Alternatively, the first and second ribs may both be extended in a direction inclined from the direction parallel to the opposite side of the separator sheet, and the separator sheet may be folded in half with the axis inclined from the direction perpendicular to the opposite side of the separator sheet. This allows the angle at which the first and second ribs intersect to be made larger. As a result, it becomes easier to make the first and second ribs intersect at the joint and to make them intersect at multiple locations. Consequently, variations in joint strength are further reduced, and the joint strength can be further increased.

[0030] In this case, it is preferable for the first rib in the electrode plate region to extend in the same direction as the first rib in the joining region, in terms of ease of rib processing. Similarly, it is preferable for the second rib in the electrode plate region to extend in the same direction as the second rib in the joining region, in terms of ease of rib processing.

[0031] Preferably, the first rib includes a plurality of first joining ribs provided at regular intervals in the joining region within the first region, and a plurality of first electrode plate ribs provided at regular intervals in the electrode plate region within the first region. In this case, the intervals at which the first joining ribs are provided may be narrower than the intervals at which the first electrode plate ribs are provided. This allows more first ribs to intersect with the second ribs in the joining region. Similarly, preferably, the second rib includes a plurality of second joining ribs provided at regular intervals in the joining region within the second region, and a plurality of second electrode plate ribs provided at regular intervals in the electrode plate region within the second region. In this case, the intervals at which the second joining ribs are provided may be narrower than the intervals at which the second electrode plate ribs are provided. This allows more first ribs to intersect with the second ribs in the joining region. By increasing the number of intersection points between the first ribs and the second ribs at the joint, the joint strength can be maintained at a high level.

[0032] Preferably, the separator has a third region on the back surface of the first region and a fourth region on the back surface of the second region, with a plurality of third ribs provided within the third region and a plurality of fourth ribs provided within the fourth region. The outer surfaces of the bag-shaped separator after joining are the third surface and the fourth surface. In the bag-shaped separator after joining, the third region is on the third surface and the fourth region is on the fourth surface. The third ribs and the fourth ribs prevent the electrode plate of either the positive electrode plate or the negative electrode plate that is not housed in the separator bag from coming into close contact with the separator. The third ribs and the fourth ribs provided in the electrode plate region prevent tearing and / or penetration short circuits due to oxidative degradation of the separator caused by contact with the other electrode plate. Hereafter, the third ribs and the fourth ribs will be collectively referred to as "outer ribs".

[0033] A bag-shaped separator with internal and external ribs can improve battery performance. However, in this case, in order to maintain high charge-discharge characteristics, the total thickness of the separator must be reduced, which necessitates thinning the base portion of the separator. As a result, the bonding strength at the separator ends tends to decrease, and the problem of variations in bonding strength becomes more serious.

[0034] The third rib may be provided in the region within the third region that corresponds to the joining region within the first region (i.e., the region on the back side of the joining region within the first region). The fourth rib may also be provided in the region within the fourth region that corresponds to the joining region within the second region (i.e., the region on the back side of the joining region within the second region). In this case, when forming a joint by crimping or the like, the third rib or the fourth rib (outer rib) is also compressed together. This makes it possible to increase the compression ratio and gain joint strength, but it also makes the variation in joint strength due to variations in the positioning of the joint ends more pronounced. However, by having the first rib and the second rib intersect at the joint, it is possible to suppress other ribs from getting stuck in the valleys between adjacent ribs, and to maintain high joint strength.

[0035] In this way, by aligning the first and second regions so that the first and second ribs intersect at the joint, and forming a joint, variations in the joint strength of the bag-shaped separator are reduced, and the joint strength can be maintained. The above effect is not limited to the crimping method using gear seals, but can also be obtained with heat welding, etc. Forming a joint may include joining at least a part of the first region and at least a part of the second region by crimping or welding.

[0036] In one embodiment of the present invention, a method for manufacturing a lead-acid battery may further include arranging a negative electrode plate so that it is housed in a bag-shaped separator. As a method for housing the negative electrode plate, the negative electrode plate can be pressed against the electrode plate area in a first area or an electrode plate area in a second area of ​​a separator sheet, and then the separator can be folded in half to form a joint with the negative electrode plate sandwiched between the first and second areas. In this case, the formation of the joint and the housing of the negative electrode plate in the bag-shaped separator are performed in parallel. However, the negative electrode plate may be housed in the bag-shaped separator after the joint has been formed and the separator has been processed into a bag shape.

[0037] Bag-shaped separators are effective as separators used in lead-acid batteries, particularly when housing negative electrode plates, and can improve resistance to short-circuit penetration.

[0038] The following describes in detail, with reference to the drawings, a method for manufacturing a lead-acid battery according to an embodiment of the present invention, particularly the configuration of the separator. However, the present invention is not limited to the following embodiments. Furthermore, the following drawings emphasize the appearance of the internal ribs in the bonding region of the separator, and the actual composition ratio of each part of the separator may not match the corresponding composition ratio of each part in the drawings.

[0039] Figure 1 shows a schematic diagram of a lead-acid battery separator used in the method according to an embodiment of the present invention, viewed from the outside of the bag. Figure 2 shows a schematic separator sheet before the separator in Figure 1 is processed into a bag shape. The separator 100 comprises a bag-shaped base portion 101 made of a microporous membrane, internal ribs 102a to 102d protruding from the inner surface (first or second surface) of the base portion 101, and external ribs 104a and 104b protruding from the outer surface (third surface) of the base portion 101. However, the internal ribs 102a to 102d are located inside the bag-shaped separator and are therefore not shown in Figure 1. When a negative electrode plate is housed in the separator 100, the internal ribs 102a to 102d are located on the negative electrode plate side, and the external ribs 104a and 104b are located on the positive electrode plate side. When the positive electrode plate is housed within the separator 100, the outer ribs 104a and 104b are located on the negative electrode plate side, and the inner ribs 102a to 102d are located on the positive electrode plate side. Both configurations are possible, where the negative electrode plate is housed within the separator 100 and where the positive electrode plate is housed within the separator 100.

[0040] The separator 100 may be formed from a polymer material. At least the base portion is a porous sheet, which can also be called a porous film. The separator 100 may contain a filler (e.g., a particulate filler such as silica, and / or a fibrous filler) dispersed in a matrix formed from the polymer material. The separator 100 is preferably made of an acid-resistant polymer material. Polyolefins such as polyethylene and polypropylene are preferred as such polymer materials.

[0041] The average thickness of the base portion 101 is, for example, 0.15 mm or more and 0.3 mm or less, preferably 0.18 mm or more and 0.27 mm or less. When the average thickness of the base portion is within such a range, it becomes easier to secure the height of the inner ribs and, if necessary, the outer ribs while maintaining high charge-discharge characteristics. The average thickness of the base portion is obtained by measuring the thickness of the base portion at five arbitrarily selected locations in the cross-sectional photograph of the separator and averaging them.

[0042] The separator 100 has a plate region 106, a joining region 108a provided on the left end side of the separator, and a joining region 108b provided on the right end side of the separator. Joining (joint portions) 109a and 109b of the first surface and the second surface are formed in each of the joining regions 108a and 108b.

[0043] Inner ribs 102a (first plate rib) and inner ribs 102b (second plate rib) are provided on the first surface and the second surface of the plate region 106 (see FIGS. 2 to 5), and an outer rib 104a is provided on the third surface of the plate region 106. When a lead storage battery is constructed, in the plate region 106, the separator 100 faces the positive electrode plate or the negative electrode plate. At this time, the inner ribs 102a, 102b, and the outer rib 104a prevent the base portion 101 from directly contacting the positive electrode plate or the negative electrode plate. On the other hand, inner ribs 102c (first joining rib) and inner ribs 102d (second joining rib) are provided on the first surface and the second surface of the joining regions 108a and 108b (see FIGS. 2 to 5). Also, an outer rib 104b is provided on the third surface of the joining regions 108a and 108b.

[0044] The separator 100 shown in FIG. 1 is formed by bending a single separator sheet in which the inner ribs 102a to 102d and the outer ribs 104a and 104b are pre-formed into a U shape, folding it in half, and joining the left end side and the right end side by a method such as a gear seal. FIG. 2 schematically shows a rectangular separator sheet 110 before being folded in half and forming a joint on the left and right end sides. Note that FIG. 2 is a schematic view of the separator sheet seen from the surface on which the inner ribs 102a to 102d are formed, and the outer ribs 104a and 104b are not shown because they are on the back side.

[0045] The separator sheet 110 has a first region (the region above the axis X parallel to the short side of the separator sheet in FIG. 2) and a second region (the region below the axis X in FIG. 2). When the first region and the second region are opposed to each other, the first region becomes the first surface of the bag-shaped separator, and the second region becomes the second surface of the bag-shaped separator.

[0046] As shown in FIG. 2, inner ribs 102a are provided in the electrode plate region 106 in the first region, and inner ribs 102b are provided in the electrode plate region 106 above the second region. Inner ribs 102c are provided in the joining regions 108a and 108b in the first region, and inner ribs 102d are provided in the joining regions 108a and 108b in the second region. The inner ribs 102a to 102d are each formed in a linear stripe pattern at a predetermined interval in a direction parallel to the long side of the separator sheet. In FIG. 2, the rib intervals of the inner ribs 102c and 102d provided in the joining regions 108a and 108b are made narrower than the rib intervals of the inner ribs 102a and 102b provided in the electrode plate region 106.

[0047] In the present embodiment, when the separator sheet shown in FIG. 2 is folded in half to form the bag-shaped separator 100 shown in FIG. 1, the separator sheet is not bent about the axis X parallel to the short side of the separator sheet, but as shown by the chain line in FIG. 2, the separator sheet is bent about the axis Y slightly shifted from the direction parallel to the short side, and the left and right end portions of the joining regions 108a and 108b are joined. As a result, when the first region and the second region are opposed to each other to form a bag-shaped separator, the inner ribs 102a to 102d extend in a direction slightly inclined from the vertical direction. Also, the inner ribs 102a and 102c on the first surface and the inner ribs 102b and 102d on the second surface extend inclined from the vertical direction in opposite directions. Therefore, when the first region and the second region are opposed to each other, the inner ribs 102c and 102d can be made to intersect at each of the joining regions 108a and 108b. At this time, the inner ribs 102a and 102b also intersect in the electrode plate region 106. And when forming the joint, the intersection of the inner ribs 102c and 102d is made to be included in at least one location in the joint portion.

[0048] When joining the left and right ends of the joining regions 108a and 108b, intersecting the inner ribs 102c and 102d at the joint makes it easier to prevent one of the inner ribs 102c from getting stuck in the grooves between the inner ribs 102d provided at predetermined intervals on the second region, or preventing one of the inner ribs 102d from getting stuck in the grooves between the inner ribs 102c provided at predetermined intervals on the first region. As a result, variations in joining strength are reduced, and joining strength can be maintained.

[0049] Figure 3 shows the state of the inner ribs of the separator sheet in the joining region 108a when the first region and the second region are facing each other. In Figure 3, the outer ribs are omitted to avoid clutter.

[0050] When the separator sheet shown in Figure 2 is folded in half, if the folding axis is offset from the axis X parallel to the short side of the separator sheet, and the offset angle is small, then, depending on the positional relationship of the inner ribs 102c and 102d, the inner ribs 102c and 102d may not overlap, as shown in Figure 3(a). In this case, the inner rib 102d fits into the groove between the inner ribs 102c, and the inner rib 102c fits into the groove between the inner ribs 102d.

[0051] On the other hand, when the displacement angle is large, as shown in Figure 3(b), the inner ribs 102c and 102d intersect regardless of their relative positions. In this case, high joint strength can be maintained.

[0052] When folding a separator sheet in half, even if the misalignment angle of the folding axis is the same, the relative position of the inner rib 102d to the inner rib 102c will vary in the left-right direction depending on the folding position of the separator sheet (position in the longitudinal direction of the separator sheet). Even when the misalignment angle is small, it is possible to make the inner ribs 102c and 102d intersect at the joint. However, depending on the folding position, both cases where the inner ribs 102c and 102d intersect and cases where they do not intersect (Figure 3(a)) can occur, which can lead to variations in joint strength. However, compared to the case where the separator sheet is folded with X as the axis, the variation in joint strength is reduced.

[0053] Let D be the spacing between the inner ribs 102c, and let L be the length of the inner ribs 102c. If θ is the angle of deviation from the direction X parallel to the shorter side of the axis Y on which the separator sheet is folded, then the inner ribs 102c and 102d are tilted by θ in opposite directions, so the intersection angle is 2θ. In this case, when tan 2θ ≥ D / L is satisfied, the inner ribs 102c can be reliably made to intersect with the inner ribs 102d at one or more locations, and the joint strength can be kept high and the variation in joint strength low. In this case, if the width from the end of the separator sheet of the joint is set so that the second inner rib 102d from the end is included, then the joint will include at least one intersection point between the inner ribs 102c and 102d. If W is the distance from the end of the inner rib 102d located closest to the end, then the joint should be set to an area that includes the end and has a width of D + W or more. Furthermore, to prevent any unjoined sections from forming, the width of the joint is determined by the offset of the separator ends (the length of the end of the separator on the joint side when folded in half is L). ２ As L ２ It is preferable to set it to exceed tan(2θ).

[0054] Figures 4 and 5 are schematic diagrams showing a different form of separator sheet than that shown in Figure 2. In the separator sheet 111 shown in Figure 4, the inner ribs 102a to 102d are not extended in a direction parallel to the long side of the separator sheet (vertical direction) as in Figure 2, but are extended in a direction slightly inclined from the direction parallel to the long side. In this case, when the separator sheet 111 is folded in half with axis X parallel to the short side of the separator sheet as the axis, the inner ribs 102a and 102c in the first region and the inner ribs 102b and 102d in the second region extend in inclined directions from the vertical. Therefore, when the first and second regions are placed opposite each other and a joint is formed on the left and right end sides, the inner ribs 102c and 102d can be made to intersect at the joint in the joint regions 108a and 108b. Furthermore, at this time, the inner rib 102a and the inner rib 102b intersect in the electrode plate region 106.

[0055] In Figure 4, the axis for folding the separator sheet 111 in half may be tilted from a direction parallel to the short side of the separator sheet, as shown by axis Y in Figure 2. This allows for a larger angle at which the inner ribs 102c and 102d intersect, making it easier to intersect the inner ribs 102c and 102d at the joint.

[0056] The separator sheet 112 shown in Figure 5 has internal ribs 102c and 102d in the joining region arranged not in straight lines, but in a striped pattern of curves that extend substantially vertically while undulating. In this case, when the separator sheet is folded in half along an axis parallel to the short side of the separator sheet, and the first and second regions are placed opposite each other, one internal rib 102c can intersect with one or more internal ribs 102d at multiple points in the joining regions 108a and 108b. Also, one internal rib 102d can intersect with one or more internal ribs 102c at multiple points. As the number of intersection points increases, variations in joining strength are further reduced, and high joining strength can be maintained.

[0057] The average height of the inner ribs in the bonding region is preferably 0.05 mm or more from the viewpoint of puncture strength at the ends, and preferably 0.5 mm or less from the viewpoint of suppressing bonding defects due to insufficient bonding energy, etc. The average height of the inner ribs in the electrode plate region is preferably 0.3 mm or more when facing the positive electrode plate to suppress oxidative degradation, and preferably 0.05 mm or more when facing the negative electrode plate to suppress penetration short circuit. On the other hand, the average height of the inner ribs in the electrode plate region is preferably 0.5 mm or less from the viewpoint of maintaining a high discharge capacity. The height of the inner rib refers to the distance from the main surface (first region or second region) of the base part of the separator sheet to the top of the inner rib at a predetermined position of the inner rib. The average height of the inner rib is obtained by averaging the heights of the inner ribs measured at 10 arbitrarily selected locations on one of the main surfaces of the base part.

[0058] In Figures 2 to 5, a stripe-like pattern is exemplified as the pattern of the internal ribs 102a to 102d. However, the pattern of the internal ribs is not particularly limited. The internal ribs may be formed randomly, or they may be formed in a stripe, curved, or grid pattern. Also, as exemplified in Figure 5, the pattern of the internal ribs may differ between the electrode plate region and the bonding region. From the viewpoint of making the electrolyte more easily diffused, it is preferable to form multiple internal ribs in a stripe pattern in at least the electrode plate region within the first or second region. The orientation of the stripe-like internal ribs is not particularly limited; for example, multiple internal ribs may be formed along the height direction or the width direction. From the viewpoint of suppressing the increase in internal resistance due to the accumulation of gas generated during charging, it is preferable to form multiple internal ribs in a stripe pattern along the height direction. On the other hand, from the viewpoint of suppressing the sedimentation of high-concentration sulfuric acid generated during charging and suppressing stratification, it is preferable to form multiple internal ribs in a stripe pattern along the width direction. Note that the height direction refers to the direction in which the opening of the bag-shaped separator is located, and the width direction refers to the direction perpendicular to the height direction.

[0059] Figure 6 is a schematic diagram showing a different form of separator sheet from Figures 2, 4, and 5. Figure 6 is a view of the separator sheet 114 from the third region (fourth region) side, but by folding the right-angled triangular region in the upper right back toward the paper plane, the state of the first region (second region) side is also shown. A bag-shaped separator is formed by folding the separator sheet 114 in half (mountain fold) so that the paper plane side of the separator sheet 114 becomes the outer surface and the back side of the paper plane becomes the inner surface, and then facing the first region and the second region. At this time, one of the opposing inner surfaces of the folded separator sheet 114 constitutes the first surface, and the other constitutes the second surface. Of the outer surfaces of the folded separator sheet 114, the outer surface located on the separation side of the first surface constitutes the third surface, and the outer surface located on the separation side of the second surface constitutes the fourth surface.

[0060] In the separator sheet 114 shown in Figure 6, multiple outer ribs 104a and 104b are formed to be arranged in a stripe pattern along the height direction (parallel to the long side of the sheet). On the other hand, multiple inner ribs 102e are formed to be arranged in a stripe pattern along the width direction (parallel to the short side of the sheet). The spacing of the inner ribs 102e is the same in both the joining region and the electrode plate region. However, the spacing of the outer ribs 104b in the joining region is narrower than that of the outer ribs 104a in the electrode plate region. The separator sheet 114 is suitably used when housing a negative electrode plate in a bag-shaped separator. In the separator sheet 114 as well, the separator sheet can be folded around a direction Y that is slightly offset from the direction parallel to the short side of the separator sheet, forming a joint, which allows opposing inner ribs 102e to intersect.

[0061] By using the separator sheets shown in Figures 2 and 4 to 6, the multiple inner ribs can be extended in a direction slightly inclined from the height direction of the bag-shaped separator, or in a direction slightly inclined from the width direction, but even in these cases, the above-mentioned effects can be obtained.

[0062] The spacing of the striped or grid-like internal ribs is preferably 0.5 mm to 10 mm in the electrode plate region, from the viewpoint of puncture strength, oxidation resistance, and penetration short-circuit resistance. For example, it is preferable that internal ribs are formed with such spacing in 70% or more of the area of ​​the electrode plate region.

[0063] In contrast, it is preferable to make the spacing of the internal ribs in the joining region denser than that of the internal ribs in the electrode region, as this ensures that the internal ribs intersect reliably and increases the number of intersection points. Specifically, the spacing of the striped or grid-like internal ribs in the joining region is preferably narrower than the spacing of the internal ribs in the electrode region, and is between 0.5 mm and 2.0 mm. The spacing of the internal ribs is the distance between the tops of adjacent first or second ribs (more specifically, the distance between the centers of adjacent internal ribs in the direction that crosses the internal ribs).

[0064] The average height of the outer ribs in the electrode plate region is preferably 0.3 mm or more when facing the positive electrode plate to suppress oxidative degradation, and preferably 0.05 mm or more when facing the negative electrode plate to suppress penetration short circuits. On the other hand, the average height of the outer ribs in the electrode plate region is preferably 0.5 mm or less from the viewpoint of maintaining high charge-discharge characteristics. The average height of the outer ribs in the bonding region is preferably 0.05 mm or more from the viewpoint of puncture strength at the ends, and preferably 0.5 mm or less in order to suppress bonding defects due to insufficient bonding energy, etc. The average height of the outer ribs is determined in the same way as for the inner ribs. The height of the outer ribs is the distance from the main surface (third region or fourth region) of the base part of the separator sheet at a predetermined position on the outer rib to the top of the outer rib, in the same way as for the inner ribs.

[0065] The pattern and orientation of the outer ribs are not particularly limited, similar to the inner ribs. For example, they can be selected from those described above for the inner ribs. The spacing of the striped or grid-like outer ribs is preferably 0.5 mm to 10 mm in the electrode plate region, from the viewpoint of puncture strength, oxidation resistance, and penetration short-circuit resistance. For example, it is preferable that outer ribs with such a pitch are formed in 70% or more of the area of ​​the electrode plate region.

[0066] In contrast, the spacing of the outer ribs in the joining region is preferably narrower than the spacing of the outer ribs in the electrode region, and is preferably 0.5 mm to 2.0 mm, from the viewpoint of increasing the compression ratio when joining by a crimping method or the like, and thereby increasing the joining strength. The spacing of the outer ribs refers to the distance between the tops of adjacent third or fourth ribs (more specifically, the distance between the centers of adjacent outer ribs in the direction that crosses the outer ribs).

[0067] The above-mentioned ranges for the spacing and height of the inner ribs and the outer ribs are, unless otherwise specified, particularly suitable when the separator accommodates a negative electrode plate. When the separator accommodates a positive electrode plate, the above-mentioned ranges for the spacing and height of the outer ribs in the electrode plate region can be selected as the range for the spacing and height of the inner ribs in the electrode plate region, and the above-mentioned ranges for the spacing and height of the inner ribs in the electrode plate region can be selected as the range for the spacing and height of the outer ribs in the electrode plate region.

[0068] A separator can be obtained, for example, by extruding a resin composition containing a pore-forming agent (such as a solid pore-forming agent like polymer powder, and / or a liquid pore-forming agent like oil) and a polymer material into a sheet, then removing the pore-forming agent to form pores in the matrix of the polymer material. Ribs may be formed, for example, during extrusion molding, or they may be formed after the sheet is formed or after the pore-forming agent is removed by transferring them using a roller or the like equipped with grooves corresponding to the ribs. If a filler is used, it is preferable to add it to the resin composition.

[0069] The following describes in detail an example of a lead-acid battery using a bag-shaped separator manufactured by the method of this embodiment, focusing on each major component. However, the present invention is not limited to the following embodiment. Furthermore, since the bag-shaped separator described above is used as the separator for the lead-acid battery, components other than the separator will be described.

[0070] (Electrolyte) The electrolyte is an aqueous solution containing sulfuric acid. The electrolyte may be gelled as needed. The electrolyte may contain additives used in lead-acid batteries as needed. The specific gravity of the electrolyte in a fully charged lead-acid battery after chemical conversion at 20°C is, for example, 1.10 g / cm³. 3 1.35g / cm or more 3 The following applies:

[0071] (Positive electrode plate) Lead-acid batteries have two types of positive electrode plates: paste type and clad type. A paste-type positive electrode plate comprises a positive electrode current collector and a positive electrode material. The positive electrode material is held in place by the positive electrode current collector. In a paste-type positive electrode plate, the positive electrode material is the positive electrode plate with the positive electrode current collector removed. The positive electrode current collector can be formed in the same way as the negative electrode current collector, and can be formed by casting lead or a lead alloy, or by processing a lead or lead alloy sheet.

[0072] A clad cathode plate comprises multiple porous tubes, a core inserted into each tube, a cathode electrode material filled into the tubes with the cores inserted, and a connecting seat that links the multiple tubes. In a clad cathode plate, the cathode electrode material is the cathode plate without the tubes, cores, and connecting seat.

[0073] For the positive electrode current collector, Pb-Ca alloys and Pb-Ca-Sn alloys are preferred as lead alloys in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have lead alloy layers of different compositions, and may have multiple alloy layers. For the core metal, it is preferable to use Pb-Ca alloys or Pb-Sb alloys.

[0074] The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) that exhibits capacity through a redox reaction. The positive electrode material may also contain other additives, such as antimony (Sb), as needed.

[0075] Unformed paste-type positive electrode plates are obtained by filling a positive electrode current collector with positive electrode paste, followed by curing and drying, similar to the process for negative electrode plates. The positive electrode paste is prepared by mixing lead powder, additives, water, and sulfuric acid. Unformed clad-type positive electrode plates are formed by filling tubes into which core metals are inserted with a mixture of additives and lead powder or slurry-like lead powder as needed, and then joining multiple tubes together in a linkage. Subsequently, the unformed positive electrode plates are formed by chemically transforming them.

[0076] (Negative electrode plate) The negative electrode plate of a lead-acid battery consists of a negative electrode current collector and a negative electrode material. The negative electrode material is the negative electrode plate with the negative electrode current collector removed. The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. Examples of processing methods include expansion and punching.

[0077] 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, etc.

[0078] The negative electrode material contains a negative electrode active material (lead or lead sulfate) that exhibits capacity through an oxidation-reduction reaction, and may also contain shrinkage inhibitors, carbonaceous materials such as carbon black, barium sulfate, and other additives as needed.

[0079] The negative electrode active material in the charged state is spongy lead, but the unformed negative electrode plate is usually made using lead powder.

[0080] The negative electrode plate can be formed by filling a negative electrode current collector with negative electrode paste, allowing it to mature and dry to produce an unformed negative electrode plate, and then forming the unformed negative electrode plate. The negative electrode paste is prepared by kneading lead powder, an organic shrinkage inhibitor, and various additives as needed, with water and sulfuric acid.

[0081] Chemical formation can be carried out by housing the unformed positive and negative electrode plates within the battery case of a lead-acid battery. If necessary, the electrolyte may be injected and chemical formation may be carried out within the battery case after inter-cell connections and lid welding are performed. Alternatively, the positive and negative electrode plates may be formed individually before assembling the lead-acid battery or the electrode plate group.

[0082] Figure 7 shows the external appearance of an example of a lead-acid battery using a bag-shaped separator. The lead-acid battery 1 comprises a battery case 12 that houses an electrode plate group 11 and an electrolyte (not shown). The inside of the battery case 12 is divided into a number of cell chambers 14 by a partition wall 13. Each cell chamber 14 houses one electrode plate group 11. The opening of the battery case 12 is closed with a lid 15 equipped with a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a liquid inlet plug 18 for each cell chamber. When replenishing water, the liquid inlet plug 18 is removed and the water is supplied. The liquid inlet plug 18 may also have a function of discharging gas generated in the cell chamber 14 to the outside of the battery.

[0083] Each electrode plate group 11 is constructed by stacking multiple negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the bag-shaped separator 4 may also house the positive electrode plates 3. In the cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects multiple negative electrode plates 2 in parallel is connected to a through-connector 8, and a positive electrode shelf 5 that connects multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 on the outside of the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode shelf 6, and a through-connector 8 is connected to the positive electrode shelf 5. The negative electrode column 9 is connected to a negative electrode terminal 16 on the outside of the lid 15. Each through-connector 8 passes through a through-hole provided in the partition wall 13, connecting the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0084] [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0085] 《Lead-acid battery A1》 (1) Preparation of negative electrode plate A negative electrode paste was obtained by mixing lead powder, water, dilute sulfuric acid, carbon black, and an organic shrinkage inhibitor. The negative electrode paste was filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy, which served as the negative electrode current collector, and then aged and dried to obtain an unformed negative electrode plate. Sodium ligninsulfonate was used as the organic shrinkage inhibitor. The carbon black and the organic shrinkage inhibitor were added to the negative electrode paste in amounts adjusted so that their respective content in 100% by mass of the negative electrode material was 0.2% by mass.

[0086] (2) Preparation of the positive electrode plate Lead powder, water, and sulfuric acid were kneaded together to prepare a positive electrode paste. The positive electrode paste was filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy, which was to be used as the positive electrode current collector. The grid was then aged and dried to obtain an unformed positive electrode plate.

[0087] (3) Separator Fabrication A separator sheet made of a microporous polyethylene membrane with ribs formed on both sides was folded in half, and the left and right ends were joined to form a bag-shaped separator S1. In the separator sheet shown in Figure 2, the spacing of the inner ribs was 2.0 mm in the electrode plate region and 1.0 mm in the joining region (peripheral region from the left and right ends to 5 mm), and the height of the inner ribs was 0.1 mm in both the electrode plate region and the joining region. The spacing of the outer ribs was 8.0 mm in the electrode plate region and 1.0 mm in the joining region, and the height of the outer ribs was 0.4 mm in the electrode plate region and 0.2 mm in the joining region. The average thickness of the base portion of the separator was 0.25 mm.

[0088] Furthermore, all ribs, including the inner and outer ribs, have a roughly isosceles trapezoidal cross-sectional shape at the protruding portion, and the width of the ribs was set to 0.25 mm at the bottom of the separator base surface and 0.15 mm at the top. Ribs were arranged in the first to fourth regions within the separator sheet so that inner ribs were formed on both sides of the inner surface (first and second surfaces) of the bag-shaped separator, and outer ribs were formed on both sides of the outer surface (third and fourth surfaces). The separator sheet was rectangular in shape with a long side length of 250 mm and a short side length of 152 mm, and all ribs were formed in a stripe pattern extending linearly parallel to the long side of the separator sheet.

[0089] When folding the separator sheet in half, the folding direction was slightly offset from the direction parallel to the short side so that the opposing inner ribs did not overlap (Figure 3(a)). Then, the 3 mm regions at the left and right ends were joined using the gear seal method to obtain a bag-shaped separator. The length L of the inner ribs, excluding the folding allowance, was 124 mm in both the first and second regions, as well as in the joining region and the electrode plate region, and the distance D between the tops of the inner ribs in the joining region was 1.0 mm as described above. The distance W from the end to the top of the inner rib located closest to the end was 0.4 mm. The deviation angle θ of the axis Y from the direction X parallel to the short side was 0.2° (angle between the inner ribs 2θ = 0.4°).

[0090] With the unformed negative electrode plate pressed against the first region of the separator sheet, the separator sheet was folded, and the left and right ends were joined together, performing the bag-shaped processing of the separator and the housing of the negative electrode plate in parallel.

[0091] (4) Fabrication of the lead-acid battery A bag-shaped separator S1 containing the negative electrode plate and the positive electrode plate were stacked to form an electrode plate group consisting of eight unformed negative electrode plates and eight unformed positive electrode plates per cell. The electrode plate group was inserted into a polypropylene battery case, electrolyte was poured in, and the electrode plate group was formed inside the battery case to assemble a liquid-type lead-acid battery A1 with a nominal voltage of 12V and a nominal capacity of 48Ah (5-hour rate).

[0092] In the fabrication of the separator S1 for lead-acid battery A2, the axis of folding the separator sheet in half was changed. The angle of deviation θ of the folding axis Y from the direction X parallel to the short side was set to 0.5° (intersection angle of the inner ribs 2θ = 1°) so that the opposing inner ribs intersect (Figure 3(b)). Other than this, lead-acid battery A2 was fabricated in the same manner as lead-acid battery A1.

[0093] For lead-acid battery A3, a bag-shaped separator different from separator S1 was created. A single separator sheet made of a microporous polyethylene membrane with ribs on both sides was folded in half, and the left and right ends were joined to form a bag-shaped separator S2. In the separator sheet shown in Figure 6, the spacing of the inner ribs was set to 0.5 mm in both the electrode plate region and the joining region (peripheral region up to 5 mm from the left and right ends), and the height of the inner ribs was set to 0.1 mm in both the electrode plate region and the joining region. The spacing of the outer ribs was set to 8.0 mm in the electrode plate region and 0.5 mm in the joining region, and the height of the outer ribs was set to 0.4 mm in the electrode plate region and 0.2 mm in the joining region. The average thickness of the base portion of the separator was 0.25 mm.

[0094] Furthermore, all ribs, including the inner and outer ribs, have a roughly isosceles trapezoidal cross-sectional shape at the protruding portion, and the width of the ribs is 0.2 mm at the bottom of the separator base surface and 0.1 mm at the top. Ribs were arranged in the first to fourth regions within the separator sheet so that inner ribs were formed on both sides of the inner surface (first and second surfaces) of the bag-shaped separator, and outer ribs were formed on both sides of the outer surface (third and fourth surfaces). The separator sheet is rectangular with a long side length of 250 mm and a short side length of 152 mm, and all inner ribs are formed in a stripe pattern extending linearly perpendicular to the long side of the separator sheet, and all outer ribs are formed in a stripe pattern extending linearly parallel to the long side of the separator sheet.

[0095] When folding the separator sheet in half, the folding direction was slightly offset from the direction parallel to the short side, so that the opposing inner ribs did not overlap. Then, the 3 mm regions at the left and right ends were joined using the gear seal method to obtain a bag-shaped separator. The length L of the inner ribs, excluding the folding allowance, was 152 mm, which is equal to the length of the short side of the separator sheet, in both the first and second regions, as well as in the joining region and the electrode plate region. The spacing D between the tops of the inner ribs in the joining region was 0.5 mm as described above. The distance W from the end to the top of the inner rib located closest to the end was 0 mm. The deviation angle θ of the axis Y from the direction X parallel to the short side was 0.05° (angle between the inner ribs 2θ = 0.1°). The length of the outer rib, excluding the bending allowance, was 124 mm in both the joining region and the main region, and the spacing between the tops of the outer ribs in the joining region was 0.5 mm as described above. The distance from the end to the top of the outer rib located closest to the end was 0.4 mm.

[0096] A negative electrode plate was placed in the separator S2 to form an electrode plate group, and lead-acid battery A3 was manufactured. <Lead-acid battery A4> In the manufacture of separator S2, when folding the separator sheet in half, the axis of folding the separator sheet was changed. The angle of deviation θ of the axis Y of folding the separator sheet from the direction X parallel to the short side was set to 0.5° (intersection angle of the inner ribs 2θ = 1°) so that the opposing inner ribs intersect. Lead-acid battery A4 was manufactured in the same manner as lead-acid battery A3.

[0097] Lead-acid battery B1 was manufactured in the same manner as lead-acid battery A1, except that the positive electrode plate was housed in the separator S1 to form the electrode plate group.

[0098] Lead-acid battery B2: Lead-acid battery B2 was manufactured in the same manner as lead-acid battery A2, except that the positive electrode plate was housed in the separator S1 to form the electrode plate group. In lead-acid batteries B1 and B2, the spacing of the inner ribs of the separator sheet was 8.0 mm in the electrode plate region and 1.0 mm in the bonding region (peripheral region from the left and right ends up to 5 mm), and the height of the inner ribs was 0.4 mm in the electrode plate region and 0.2 mm in the bonding region. In addition, the spacing of the outer ribs was 2.0 mm in the electrode plate region and 1.0 mm in the bonding region, and the height of the outer ribs was 0.1 mm in both the electrode plate region and the bonding region.

[0099] 《Lead-acid battery B3》 In the creation of separator S2, separator S3 was created by reversing the direction in which the separator sheet was folded. That is, in separator S3, the relationship between the inner ribs and outer ribs is reversed compared to separator S2, with the inner ribs extending linearly parallel to the long side of the separator sheet and the outer ribs extending linearly perpendicular to the long side of the separator sheet. The spacing, height, and length of the inner ribs in separator S3 are the same as the spacing, height, and length of the outer ribs in separator S2, respectively, and the spacing, height, and length of the outer ribs in separator S3 are the same as the spacing, height, and length of the inner ribs in separator S2, respectively.

[0100] Except for housing the positive electrode plate in the separator S3 to form the electrode plate group, lead-acid battery B3 was manufactured in the same manner as lead-acid battery A3.

[0101] Lead-acid battery B4: Except for housing the positive electrode plate in the separator S3 to form the electrode plate group, lead-acid battery B4 was manufactured in the same manner as lead-acid battery A4.

[0102] [Evaluation 1: Lower Short Circuit Occurrence Due to Vibration] After performing a heavy load life test as specified in JIS D 5301:2006 for 150 cycles, the following vibration test was conducted, and the incidence of lower short circuits was compared. Vibration direction: Up and down Simple harmonic motion Acceleration: 6G Frequency: 30Hz Excitation time: 2 hours

[0103] [Evaluation 2: Penetration Short-Circuit Resistance] The number of cycles in which penetration short circuits occurred was evaluated by repeatedly charging and discharging the batteries in the following cycles: 1. Discharge: 9.6A (end voltage 10.5V) 2. Constant resistance discharge: 10Ω resistor connected × 7 days 3. Charging: 14.4V / 50A × 60 minutes Steps 1 to 3 above were repeated as one cycle, and the number of cycles at which fluctuations in charging current and voltage occurred due to penetration short circuits was determined. The penetration short-circuit resistance of each lead-acid battery was evaluated as a relative ratio, with the number of cycles for lead-acid battery A1 set to 100.

[0104] Table 1 shows the evaluation results for lead-acid batteries A1-A4 and B1-B4 (Evaluation 1 and 2).

[0105]

[0106] As shown in Table 1, in lead-acid batteries A2 and A4, where the internal ribs were arranged to intersect in the bonding region, no lower short circuits occurred during the vibration test. This is thought to be because the bonding strength of the bag-shaped separator was improved, preventing seal detachment at the separator ends, and suppressing short circuits caused by contact between the precipitate derived from the positive electrode active material accumulated at the bottom of the battery case and the negative electrode plate during the heavy load life test. In contrast, in lead-acid batteries A1 and A3, lower short circuits occurred with a high probability of 20%. This is thought to be because the bonding strength of the bag-shaped separator was insufficient, causing some of the bag-shaped separator's bonding to detach during the vibration test, resulting in contact between the precipitate derived from the positive electrode active material and the negative electrode plate through the detached portion, leading to a short circuit.

[0107] Furthermore, lead-acid batteries A2 and A4 also exhibit improved resistance to penetrating short circuits compared to lead-acid batteries A1 and A3. This is thought to be because the intersecting internal ribs slightly thicken the crimped area after the gear seal, slightly increasing the distance between the negative electrode plate and the separator in the bonding region at the separator end or in the region between the bonding region and the electrode plate region. This suppresses contact between the negative electrode plate and the separator around the end, thereby suppressing penetrating short circuits.

[0108] Thus, the manufacturing method of the bag-shaped separator in this embodiment is particularly effective when the bag-shaped separator houses a negative electrode plate, and can partially solve the unique problems that arise in lead-acid batteries with a configuration in which the negative electrode plate is housed in a bag-shaped separator.

[0109] When lead-acid batteries were manufactured using the same method by housing the positive electrode plate in a bag-shaped separator, and vibration tests were performed in the same manner to evaluate their resistance to penetrating short circuits, the results were as shown for lead-acid batteries B1 to B4 in Table 1. Similar to the case where the negative electrode plate is housed in the bag-shaped separator, lower short circuits are suppressed by crossing the internal ribs at the joint. On the other hand, when the positive electrode plate is housed in the bag-shaped separator, the distance between the negative electrode plate and the separator at the separator end is sufficiently ensured by not housing the negative electrode plate. For this reason, lead-acid batteries B2 and B4, in which the internal ribs cross at the joint, and lead-acid batteries B1 and B3, in which the internal ribs do not cross at the joint, all achieved the same resistance to penetrating short circuits as lead-acid batteries A2 and A4.

[0110] A method for manufacturing a lead-acid battery according to one aspect of the present invention is applicable to the manufacture of separators used in valve-regulated and liquid-type lead-acid batteries, and can be suitably used as a power source for starting automobiles or motorcycles.

[0111] 1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive electrode column 8: Through connector 9: Negative electrode column 11: Electrode plate group 12: Battery case 13: Partition wall 14: Cell chamber 15: Cover 16: Negative electrode terminal 17: Positive electrode terminal 18: Electrode cap 100: Separator 101: Base part 102a-102e: Inner ribs 104a, 104b: Outer ribs 106: Electrode plate area 108a, 108b: Joint area 109a, 109b: Joint 110-112, 114: Separator sheet

Claims

DEPCT641. Method for manufacturing a lead-acid battery with a group of electrodes in which multiple positive and negative electrode plates are stacked together using a separator. The method involves transforming the separator into a bag shape with two facing regions one and two. The bag-shaping process includes creating a joint containing at least one region one and at least one region two; multiple ridges one is arranged in region one; multiple ridges two are arranged in region two; and the joint creation process involves facing regions one and two so that at least one ridge one and at least one ridge two intersect at the joint.2.The method of manufacturing a lead-acid battery according to claim 1 where the joint fabrication procedure includes folding a rectangular separator sheet into two sections along a direction inclined from a direction perpendicular to the opposite side to form an axis so that the first and second regions face each other, with the first and second regions of the separator sheet on the same main surface and parallel opposite sides, and both the first and second ridges extend linearly in the same direction on the main surface in one region of the separator sheet where at least the joint is provided, and in one region of the second region of the separator sheet where at least the joint is provided.

3. The method of manufacturing a lead-acid battery according to claim 2 where both the first and second ridges extend linearly on the main surface in a direction parallel to the opposite side in the said region of the first region of the separator sheet where at least the joint is provided, and in the said region of the second region of the separator sheet where at least the joint is provided. 4.Method of manufacturing a lead-acid battery according to claim 2 where both the first and second ridges extend on the main surface in a direction perpendicular to the opposite side in such area in the first area of ​​the separator plate where at least a joint is provided and in such area in the second area of ​​the separator plate where at least a joint is provided.

5. Any one of the methods of manufacturing a lead-acid battery according to claims 1 to 4 where the external shape of the first area is a rectangle and joints are provided in each area adjacent to at least two sides forming the rectangle. 6.

7. The method of manufacturing a lead-acid battery under any one of the claims 1 through 5 where the junction area, which is arranged in the junction section, and the plate area separated from the junction area are arranged in the first and second areas, and the first ridge includes several first junction ridges arranged at uniform intervals in the junction area in the first area, and several first plate ridges arranged at uniform intervals in the plate area in the first area, and the gap at which the first junction ridges are arranged is smaller than the gap at which the first plate ridges are arranged.

8. The method of manufacturing a lead-acid battery under claim 6 where the second ridge includes several second junction ridges arranged at uniform intervals in the junction area in the second area, and several second plate ridges arranged at uniform intervals in the plate area in the second area, and the gap at which the second junction ridges are arranged is smaller than the gap at which the second plate ridges are arranged.

9. A lead-acid battery manufacturing method under any of the claims 1 through 7 where a third area is provided on the back surface of the first area and a fourth area is provided on the back surface of the second area; multiple third ridges are provided in the third area and multiple fourth ridges are provided in the fourth area.

10. A lead-acid battery manufacturing method under claim 8 where a third ridge is provided in the third area corresponding to at least the area where the junction is provided in the first area.

11. A lead-acid battery manufacturing method under any of the claims 1 through 9 where the junction fabrication process includes the connection of at least part of the first area and at least part of the second area by clamping or welding.

12. A lead-acid battery manufacturing method under any of the claims 1 through 10 which also includes the arrangement of the negative electrode plates where the negative electrode plates are stored in a separator processed into a bag shape.