Lead-acid battery and method for manufacturing a lead-acid battery

Abstract

To provide a lead-acid battery and a lead-acid battery manufacturing method that can suppress the occurrence of a short circuit.SOLUTION: A storage battery 1 includes a positive electrode 10 including a plurality of cylindrical bodies 15 housing positive electrode materials 16, and a separator 13 having a base portion 41 including a first main surface 31a facing the positive electrode 10 and a plurality of first ribs 33 provided on the first main surface 31a of the base portion 41. The first ribs 33 are two-dimensionally arranged at intervals from each other on the first main surface 31a. The protruding height of the first rib 33 is greater than the thickness of the cylindrical body 15.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a lead storage battery and a method for manufacturing the same.

Background Art

[0002] A storage battery including an electrode group is widely used as an industrial or consumer secondary battery. In particular, there is a high demand for lead storage batteries for electric vehicles (so-called batteries) or backup lead storage batteries for UPS (Uninterruptible Power Supply), disaster prevention (emergency) radios, telephones, etc. A lead storage battery includes an electrode group including a positive electrode, a negative electrode, and a separator, and an electrolytic cell that houses the electrode group. The positive electrode includes a cylindrical body, a core metal inserted into the cylindrical body and having a rod shape, and an electrode material containing an active material filled inside the cylindrical body (see, for example, Patent Document 1). The separator is disposed between the positive electrode and the negative electrode to prevent a short circuit between the positive electrode and the negative electrode. The separator has a base portion including a surface (first main surface) facing the positive electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above lead storage battery, for example, in order to improve the durability of the separator, a plurality of first ribs are provided on the first main surface of the base portion, and these first ribs may be arranged two-dimensionally with a gap therebetween. In such a lead storage battery, for example, in order to further improve stability or reliability, it is desired to suppress the occurrence of a short circuit.

[0005] Therefore, an aspect of the present invention is to provide a lead storage battery and a method for manufacturing the same that can suppress the occurrence of a short circuit. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have found that, for example, with the continuous use of a lead-acid battery, the cylindrical body of the positive electrode may expand, causing the first rib of the separator to become embedded in the cylindrical body. Consequently, the first main surface of the base portion of the separator is prone to contact with the cylindrical body. In this case, the inventors have found that this contact can lead to oxidation and deterioration of the first main surface of the separator, potentially causing a short circuit. Based on these findings, the inventors have completed one aspect of the present invention.

[0007] In other words, a lead-acid battery according to one aspect of the present invention comprises a positive electrode including a plurality of cylindrical bodies for housing a positive electrode material, a base portion including a first main surface facing the positive electrode, and a separator having a plurality of first ribs provided on the first main surface of the base portion, wherein the first ribs are arranged two-dimensionally at intervals from each other on the first main surface, and the protruding height of the first ribs is greater than the thickness of the cylindrical body.

[0008] In this lead-acid battery, since the protruding height of the first rib is greater than the thickness of the cylindrical body, even if the first rib is embedded in the cylindrical body, contact between the first main surface of the base and the cylindrical body is less likely to occur. Therefore, oxidation and deterioration of the separator caused by such contact can be suppressed. Thus, it is possible to suppress the occurrence of short circuits in the lead-acid battery.

[0009] In one embodiment, the thickness ratio obtained by dividing the protruding height of the first rib by the thickness of the cylindrical body may exceed 1.3. In this case, a lead-acid battery with excellent cycle characteristics can be realized.

[0010] In one embodiment, the cylindrical body may be made up of woven fabric. In this case, the first rib of the base portion is more easily embedded in the cylindrical body compared to the case where the cylindrical body is made up of woven fabric, so the above effect of making it difficult for the first main surface of the base portion to come into contact with the cylindrical body is particularly effective.

[0011] One embodiment includes a negative electrode positioned on the opposite side of the positive electrode side of the separator, and the base portion includes a second main surface facing the negative electrode, the second main surface of which may be provided with a second rib. In this case, the second rib makes it difficult for the negative electrode to come into contact with the second main surface of the separator, thereby suppressing oxidation and deterioration of the separator and further suppressing the occurrence of short circuits.

[0012] In one embodiment, the thickness of the cylindrical body may be 0.6 mm or less. If the thickness of the cylindrical body exceeds 0.6 mm, the deterioration of battery characteristics due to increased resistance becomes significant, so it is effective to have a thickness of 0.6 mm or less for the cylindrical body.

[0013] In one embodiment, the protrusion height of the first rib may be 1.5 mm or less. If the protrusion height of the first rib is greater than 1.5 mm, the distance between the electrode plates becomes too large, and the deterioration of battery characteristics becomes significant. Therefore, it is effective to have the protrusion height of the first rib be 1.5 mm or less.

[0014] A method for manufacturing a lead-acid battery according to one aspect of the present invention is a method for manufacturing the above-described lead-acid battery, comprising the step of arranging the positive electrode and the separator such that the first main surface of the separator faces the positive electrode. In a lead-acid battery manufactured by this method, as described above, oxidation and deterioration of the first main surface of the separator can be suppressed, and the occurrence of short circuits can be suppressed. [Effects of the Invention]

[0015] According to one aspect of the present invention, it is possible to provide a lead-acid battery and a method for manufacturing a lead-acid battery that can suppress the occurrence of short circuits. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 shows a forklift equipped with a battery pack according to one embodiment. [Figure 2] Figure 2 is a perspective view showing a portion of a storage battery according to one embodiment, with the structure cut away. [Figure 3] Fig. 3(a) is a view showing the positive electrode as seen from the third direction, and Fig. 3(b) is an enlarged cross-sectional view taken along line IIIb-IIIb in Fig. 3(a). [Figure 4] Fig. 4 is a plan view showing the negative electrode. [Figure 5] Fig. 5 is a plan view showing the negative electrode wrapped by the separator. [Figure 6] Fig. 6 is an enlarged schematic cross-sectional view showing a part of the electrode group. [Figure 7] Fig. 7(a) is a view showing the first main surface side of the separator, and Fig. 7(b) is a schematic cross-sectional view taken along line VIIb-VIIb in Fig. 7(a). [Figure 8] Fig. 8 is an enlarged view showing the upper connecting seat as seen from the second direction. [Figure 9] Fig. 9 is an enlarged schematic cross-sectional view showing a part of the electrode group according to the first modification. [Figure 10] Fig. 10(a) is a view showing the first main surface side of the separator according to the second modification, and Fig. 10(b) is a schematic cross-sectional view taken along line Xb-Xb in Fig. 10(a). [Figure 11] Fig. 11 is a table showing the evaluation test results.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0018] Figure 1 shows a forklift 100 equipped with a battery pack 200. Figure 2 is a perspective view showing a portion of the battery 1 in a cutaway. As shown in Figure 1, the forklift (electric vehicle) 100 is equipped with a battery pack 200. The forklift 100 is driven by power supplied from the battery pack 200. The battery pack 200 is composed of multiple batteries 1. As shown in Figure 2, the batteries 1 are, for example, lead-acid batteries. The batteries 1 are not limited to the forklift 100, but can be used, for example, as batteries in automobiles, or as backup power sources used during power outages. In this embodiment, the batteries 1 are, for example, clad batteries equipped with clad electrodes.

[0019] The battery 1 comprises an electrode group 3, a positive electrode terminal 5A, a negative electrode terminal 5B, a water supply valve 6, and a case 7. The case 7 has a main body 8 and a lid 9. The main body 8 is a box-shaped battery case. The main body 8 is made of a material such as polypropylene. The main body 8 houses the electrode group 3 and the electrolyte. The main body 8 is composed of four side parts and a bottom part (details will be described later). The lid 9 covers the opening of the main body 8. The lid 9 is provided with a positive electrode terminal 5A, a negative electrode terminal 5B, and a water supply valve 6 that allows for the replenishment of electrolyte (liquid). The water supply valve 6 is provided between the positive electrode terminal 5A and the negative electrode terminal 5B.

[0020] Electrode group 3 has a plurality of positive electrodes 10, a plurality of negative electrodes 12, and a plurality of separators 13. In electrode group 3, the positive electrodes 10 and negative electrodes 12 are arranged alternately. Separators 13 are located between adjacent positive electrodes 10 and negative electrodes 12. Therefore, the positive electrodes 10, separators 13, and negative electrodes 12 overlap in a predetermined direction. In this embodiment, in electrode group 3, negative electrodes 12 are arranged at the ends in the arrangement direction of the positive electrodes 10, negative electrodes 12, and separators 13 (hereinafter sometimes simply referred to as the "arrangement direction" or "stack direction"). The assembly of positive electrodes 10, negative electrodes 12, and separators 13 is also called a battery electrode group (electrode plate group). When electrode group 3 and electrolyte are housed in the main body 8, the electrolyte is present in the gaps between the positive electrodes 10 and separators 13, inside the separators 13, etc.

[0021] Figure 3(a) shows the positive electrode 10 as viewed from the direction of arrangement, and Figure 3(b) is an enlarged cross-sectional view along the line IIIb-IIIb in Figure 3(a). As shown in Figures 2 and 3(a) and (b), the positive electrode 10 is, for example, a clad-type positive electrode plate. In the storage battery 1, each positive electrode 10 is electrically connected to the positive electrode terminal 5A. Each positive electrode 10 and the positive electrode terminal 5A are electrically connected by a positive electrode strap 17. The positive electrode 10 includes a current collector 14, a plurality of cylindrical bodies 15 that house a part of the current collector 14, a positive electrode material 16 housed in the cylindrical bodies 15, and an upper connecting seat 21 and a lower connecting seat 22 attached to the current collector 14. Hereinafter, the direction along the axial direction of the cylindrical body 15 will be referred to as the first direction Z, the direction perpendicular to the first direction Z and perpendicular to the direction of arrangement will be referred to as the second direction Y, and the direction of arrangement will be referred to as the third direction X. The second direction Y is the direction along the first main surface 31a (see Figure 7(a)), which will be described later.

[0022] The current collector 14 has a plurality of core metals 14a, a connecting portion (not shown) that connects the plurality of core metals 14a, and a positive electrode lug portion 14c that protrudes from the connecting portion. The current collector 14 is formed, for example, by casting. The constituent material of the current collector 14 may be any conductive material, for example, lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenide alloys. The lead alloy may also contain selenium, silver, bismuth, etc.

[0023] Multiple core metals 14a are rod-shaped portions extending along the first direction Z and arranged in a row along the second direction Y. One end of each core metal 14a in the first direction Z is connected to a connecting portion covered by the upper connecting seat 21. The other end of each core metal 14a in the first direction Z is fixed to the lower connecting seat 22. The connecting portion is a part that supports the core metals 14a and the positive electrode lugs 14c and extends along the second direction Y. When the positive electrode 10 is housed in the case 7, the connecting portion is positioned on the positive electrode terminal 5A side in the first direction Z. The positive electrode lugs 14c are terminal portions that protrude from the connecting portion in the first direction Z and are connected to the positive electrode strap 17. In the first direction Z, the protruding direction of the positive electrode lugs 14c is opposite to the protruding direction of the core metals 14a. When the positive electrode 10 is housed in the case 7, the positive electrode lugs 14c are located on the lid 9 side in the first direction Z.

[0024] The multiple cylindrical bodies 15 are insulating members that constitute a group of active material holding tubes (clad tubes). The group of active material holding tubes is an assembly of cylindrical porous tubes, also known as a "gauntlet." Therefore, each cylindrical body 15 is provided with multiple holes. In this embodiment, the thickness of the cylindrical bodies 15 is uniform, but is not limited to this. Each cylindrical body 15 extends along the first direction Z and accommodates the corresponding core metal 14a.

[0025] The cylindrical body 15 is cylindrical in shape. However, the cylindrical body 15 may also be elliptical or rectangular (for example, a rounded rectangular tubular shape). The inner diameter of the cylindrical body 15 may be, for example, 4 mm or more. The inner diameter of the cylindrical body 15 may be, for example, 10 mm or less. The outer diameter (diameter) of the cylindrical body 15 may be, for example, 5 mm or more. The outer diameter of the cylindrical body 15 may be, for example, 12 mm or less. The thickness of the cylindrical body 15 may be, for example, 100 μm or more. The thickness of the cylindrical body 15 may be, for example, 2000 μm or less.

[0026] The cylindrical body 15 is composed of a woven fabric. The woven fabric includes knitted fabric. The outer surface of the cylindrical body 11 may have depressions or recesses (embossing). As the base material of the cylindrical body 15, an acid-resistant material can be used. The cylindrical body 15 may be a glass tube. The glass tube is composed of a tubular (e.g., cylindrical) porous tube. The glass tube may contain alkali glass (C glass). The glass tube may contain, for example, glass fibers. The glass tube may contain glass fiber bundles. The glass fiber bundles may contain a sizing agent and can be obtained, for example, by bundling glass fibers using a sizing agent. The glass tube may be obtained by braiding glass fiber bundles. The outer surface of a glass tube composed of braided glass fiber bundles may have irregularities.

[0027] The glass tube may contain a resin component. Examples of resin components include phenolic resin, acrylic resin, epoxy resin, rosin resin, terpene resin, petroleum resin, and melamine resin. The glass tube preferably contains phenolic resin from the viewpoint of suppressing uneven adhesion of the resin component and from the viewpoint of easily obtaining excellent discharge performance. A curable resin may be used as the resin component.

[0028] The positive electrode material 16 is filled inside the cylindrical body 15 together with the core metal 14a. Therefore, the core metal 14a and the positive electrode material 16 are housed in the cylindrical body 15. As shown in Figure 3(b), the positive electrode material 16 surrounds the core metal 14a inside the cylindrical body 15. The positive electrode material 16 contains active material. The active material includes both the active material after chemical formation and the raw materials of the active material before chemical formation. The positive electrode material 16 contains the active material after chemical formation. The positive electrode material 16 after chemical formation includes, for example, the raw materials of the positive electrode active material. In this embodiment, the positive electrode material 16 may include the positive electrode active material and additives. The positive electrode active material is, for example, lead powder, red lead, etc. Examples of additives include carbon materials or reinforcing short fibers, etc. The positive electrode active material after chemical formation is, for example, lead dioxide, etc.

[0029] The upper connecting seat 21 is an insulating structure attached to the connecting portion (not shown) of the current collector 14, and covers the connecting portion when viewed from the first direction Z. The upper connecting seat 21 constitutes a sealing member that seals one end of each cylindrical body 15 in the first direction Z. For example, the upper connecting seat 21 is welded to each cylindrical body 15, but is not limited to this. The upper connecting seat 21 and each cylindrical body 15 may be fixed to each other, for example, via an adhesive. The upper connecting seat 21 is provided by welding an insulating resin member to the current collector 14, for example. The lower connecting seat 22 is an insulating structure attached to a plurality of core metals 14a of the current collector 14. The lower connecting seat 22 is attached to the current collector 14 by inserting and fitting the core metals 14a of the current collector 14 into an insulating resin member, for example. The lower connecting seat 22 seals the other end of each cylindrical body 15 in the first direction Z. As a result, the position of each cylindrical body 15 at the positive electrode 10 is fixed by the upper connecting seat 21 and the lower connecting seat 22. For example, the lower connecting seat 22 is welded to each cylindrical body 15, but is not limited to this. The lower connecting seat 22 and each cylindrical body 15 may be fixed to each other by, for example, an adhesive.

[0030] Figure 4 is a plan view showing the negative electrode 12. As shown in Figure 4, the negative electrode 12 is the negative electrode plate in the storage battery 1 and is electrically connected to the negative electrode terminal 5B. Each negative electrode 12 and the negative electrode terminal 5B are electrically connected by a negative electrode strap 18. The negative electrode 12 has a current collector 12a and a negative electrode material 12b. The current collector 12a is formed, for example, by casting and has a negative electrode grid 12c and a negative electrode lug 12d. The negative electrode grid 12c is the main body of the negative electrode 12 and holds the negative electrode material 12b.

[0031] The negative electrode material 12b may include a negative electrode active material and an additive. The negative electrode active material is, for example, spongy lead. Examples of additives include barium sulfate, carbon material, lignin, or reinforcing short fibers. The negative electrode lugs 12d are terminal portions that protrude from the negative electrode grid 12c along the first direction Z and are connected to the negative electrode strap 18. The negative electrode lugs 12d and the negative electrode grid 12c do not overlap each other in the third direction X. In this embodiment, the negative electrode grid 12c is covered by a separator 13. The negative electrode grid 12c is provided with protrusions 12e and 12f. The protrusions 12e and 12f are arranged at a predetermined interval and are feet that protrude outward from the negative electrode grid 12c. The protrusions 12e and 12f protrude in the direction opposite to the protrusion direction of the negative electrode lugs 12d. In this embodiment, the protruding direction of the negative electrode lugs 12d and the protruding directions of the convex portions 12e and 12f are perpendicular to the alignment direction. Furthermore, the negative electrode lugs 12d and the negative electrode grid 12c do not overlap with each other in the alignment direction.

[0032] Returning to Figure 2, the separator 13 is a battery component (battery separator) for preventing short circuits between the positive electrode 10 and the negative electrode 12. The separator 13 electrically insulates the positive electrode 10 and the negative electrode 12 while allowing ions to pass through, and is resistant to oxidation on the positive electrode 10 side and reduction on the negative electrode 12 side. Examples of materials for such a separator 13 include glass fiber, resin, and inorganic materials. In this embodiment, the separator 13 covers the negative electrode lattice body 12c and the protrusions 12e and 12f of the negative electrode 12, while the negative electrode lugs 12d of the negative electrode 12 are exposed from the separator 13.

[0033] Next, the structure combining the negative electrode 12 and the separator 13 will be described in detail.

[0034] Figure 5 is a plan view showing the negative electrode 12 enclosed in the separator 13. As shown in Figure 5, the separator 13 encloses the negative electrode 12. As described above, the negative electrode lugs 12d of the negative electrode 12 are exposed from the separator 13, and the protrusions 12e and 12f of the negative electrode 12 are covered by the separator 13. The separator 13 is formed, for example, by folding a single separator sheet in half along the second direction Y and then sealing the desired portion. The separator 13 has a base portion 41, joint portions 42 and 43, a bent portion 44, and a sealing portion 45.

[0035] The base portion 41 includes a first main surface 31a on which a plurality of first ribs 33 are provided, and a second main surface 31b which is a plane. The joint portion 42 is provided at one end of the base portion 41 in the first direction Z. The joint portion 43 is provided at the other end of the base portion 41 in the first direction Z. Each of the joint portions 42 and 43 is located outside the negative electrode 12 in the first direction Z. Each of the joint portions 42 and 43 extends in the second direction Y. As a result, the movement of the negative electrode 12 along the first direction Z can be suppressed by the joint portions 42 and 43. The joint portions 42 and 43 do not need to be completely sealed. From the viewpoint of the fluidity of the electrolyte in the separator 13, at least one of the joint portions 42 and 43 may be provided with a region through which the electrolyte can pass. The joint portions 42 and 43 are, for example, ultrasonic welding portions, heat sealing portions, cold sealing portions, gear sealing portions, etc. The gear seal portion is a part that is mechanically bonded together by pressure applied using gears. In this embodiment, each of the joint portions 42 and 43 is a gear seal portion that extends from one end to the other end of the separator 13 in the second direction Y.

[0036] At least a portion of the bent portion 44 can contact the negative electrode grid 12c. An opening 44a is provided in a portion of the bent portion 44. The opening 44a is provided, for example, to improve the fluidity of the electrolyte within the separator 13. The opening 44a is located in a position that does not overlap with either of the convex portions 12e or 12f in the second direction Y. The opening 44a is located, for example, in the central part of the separator 13 in the first direction Z, but is not limited to this. For example, the opening 44a is formed by cutting a portion of the bent portion 44. The sealing portion 45 is located on one end side of the separator 13 in the second direction Y, and is outside the negative electrode 12 when viewed from the third direction X. The sealing portion 45 is located on the lid 9 side of the negative electrode 12 in the second direction Y. A portion of the sealing portion 45 overlaps with the joint portion 42.

[0037] The details of the stacking state of the positive electrode 10, negative electrode 12, and separator 13 included in electrode group 3 will now be explained. Figure 6 is an enlarged plan view showing a part of electrode group 3. In Figure 6, a cross-section perpendicular to the second direction Y is shown. As described above, the negative electrode 12 is enclosed by the separator 13. Therefore, as shown in Figure 6, in electrode group 3, the positive electrode 10, a part 13a of the separator 13, the negative electrode 12, and the other part 13b of the separator 13 are stacked in order along the third direction X. In addition, each positive electrode 10 is sandwiched between two different separators 13 in the third direction X. Therefore, each positive electrode 10 is sandwiched between one negative electrode 12 enclosed by one separator 13 and another negative electrode 12 enclosed by another separator 13 in the third direction X. One negative electrode 12 and the other negative electrode 12 have the same configuration, and one separator 13 and the other separator 13 have the same configuration.

[0038] In the third direction X, the first main surface 31a of each separator 13 faces the positive electrode 10, and the second main surface 31b of each separator 13 faces the negative electrode 12. Therefore, in the electrode group 3, each first main surface 31a is used as the surface facing the positive electrode 10 in the third direction X, and each second main surface 31b is used as the surface facing the negative electrode 12 in the third direction X.

[0039] Figure 7(a) is a diagram showing the first main surface 31a side of the separator 13, and Figure 7(b) is a schematic cross-sectional view along the line VIIb-VIIb in Figure 7(a). As shown in Figures 6, 7(a), and 7(b), the base portion 41 is a sheet-like portion that forms the main part of the separator 13 and is flexible. The base portion 41 includes a first main surface (front surface) 31a and a second main surface (back surface) 31b located on the opposite side of the first main surface 31a in the third direction X. The first main surface 31a of the base portion 41 is provided with a plurality of first ribs 33.

[0040] The first ribs 33 are arranged in a two-dimensional manner at intervals from one another on the first main surface 31a. In other words, the first ribs 33 are provided on the first main surface 31a so as to be scattered when viewed from the third direction X. Multiple first ribs 33 are arranged apart from each other in the first direction Z and the second direction Y.

[0041] Multiple first ribs 33 are provided, for example, to improve the durability of the separator 13 and the fluidity of the electrolyte inside the case 7. Multiple first ribs 33 are arranged on the base portion 41. Multiple first ribs 33 are projections that protrude from the first main surface 31a along the third direction X, and are arranged in a staggered pattern on the first main surface 31a when viewed from the third direction X. The proportion of the first ribs 33 on the first main surface 31a is, for example, 10% to 50% when viewed from the second direction Y. This proportion may be 15% or more, 20% or more, 45% or less, or 40% or less. The cross-section of the first rib 33 perpendicular to the first direction Z is rectangular, but is not limited to this. This cross-section may be, for example, trapezoidal or inverted trapezoidal.

[0042] The protruding height of the first rib 33 is greater than the thickness of the cylindrical body 15. The protruding height is the distance from the first main surface 31a to the top of the first rib 33 (the part furthest from the first main surface 31a) in the third direction X. The thickness of the cylindrical body 15 is 0.6 mm or less. The protruding height of the first rib 33 is 1.5 mm or less. Multiple first ribs 33 are in contact with the cylindrical body 15. Here, multiple first ribs 33 are embedded in the recesses of the woven fabric that constitute the cylindrical body 15. The width of the first rib 33 in the second direction Y is not particularly limited and may be various values. The width of the first rib 33 in the first direction Z is not particularly limited and may be various values.

[0043] The second main surface 31b is a plane. The spacing between a pair of first ribs 33 adjacent in the second direction Y is smaller than the outer diameter of the cylindrical body 15. In the second direction Y, the spacing (pitch) between a pair of first ribs 33 is, for example, 2 to 3 mm, and the outer diameter of the cylindrical body 15 is, for example, 10 mm. Note that if there is variation in the values ​​of the protruding height, thickness, width, spacing, and outer diameter, the minimum value within the variation may be adopted, the maximum value within the variation may be adopted, or the average value within the variation may be adopted (the same applies hereinafter).

[0044] Multiple rib rows RL, each consisting of multiple first ribs 33 arranged in a first direction Z, are provided in the second direction Y on the first main surface 31a. In adjacent pairs of rib rows RL, the positions of the multiple first ribs 33 in one rib row RL are offset in the first direction Z from the positions of the multiple first ribs 33 in the other rib row RL. In other words, the first ribs 33 in a given rib row RL do not overlap (are not in the same position) in the first direction Z with respect to the first ribs 33 in the adjacent rib row RL.

[0045] Figure 8 is an enlarged view showing the upper support seat 21 as seen from the second direction Y. As shown in Figure 8, the first main surface 31a side of the separator 13 on the upper support seat 21 protrudes further toward the first main surface 31a than the cylindrical body 15. In other words, the upper support seat 21 protrudes further toward the first main surface 31a than the cylindrical body 15. This allows the upper support seat 21 to regulate the distance between the cylindrical body 15 and the separator 13, preventing the first rib 33 of the base portion 41 from sinking into the cylindrical body 15.

[0046] Next, we will explain an example of a manufacturing method for battery 1.

[0047] First, prepare the separator 13 and the negative electrode 12. Position the second main surface 31b of the separator 13 opposite the negative electrode 12. By folding the separator 13 in half, a bent portion 44 is formed, and the negative electrode 12 is sandwiched between the separator 13. At this time, the negative electrode grid body 12c of the negative electrode 12 is completely covered by the second main surface 31b of the separator 13, while a part of the negative electrode lug portion 12d of the negative electrode 12 is exposed from the separator 13. Form joint portions 42, 43 and a sealing portion 45 on the separator 13. The joint portions 42, 43 are formed, for example, by gear seals. The sealing portion 45 is formed, for example, by ultrasonic welding using an ultrasonic welding device including a horn. Form an opening 44a in the bent portion 44. As a result, the separator 13 enclosing the negative electrode 12 is formed.

[0048] Next, multiple positive electrodes 10 and negative electrodes 12 enclosed in separators 13 are prepared. The positive electrodes 10 and negative electrodes 12 enclosed in separators 13 are stacked alternately. At this time, the positive electrodes 10 and separators 13 are positioned so that the first main surface 31a of the separator 13 faces the positive electrode 10. Here, the positive electrodes 10, separators 13 and negative electrodes 12 are stacked in the third direction X such that the first rib 33 and the cylindrical body 15 are in contact in the third direction X.

[0049] Next, the positive electrode strap 17 is electrically connected to the lug portion 10a of the positive electrode 10, and the negative electrode strap 18 is electrically connected to the negative electrode lug portion 12d of the negative electrode 12. This forms an electrode group 3 that includes multiple positive electrodes 10, multiple negative electrodes 12, and multiple separators 13. The electrode group 3 is housed in the main body 8. The main body 8 is sealed with a lid 9. At this time, each positive electrode 10 is electrically connected to the positive electrode terminal 5A, and each negative electrode 12 is electrically connected to the negative electrode terminal 5B. Electrolyte is supplied into the case 7 via the water supply valve 6, and the initial charge is performed. The storage battery 1 is thus manufactured.

[0050] In the above-mentioned battery 1, since the protruding height of the first rib 33 is greater than the thickness of the cylindrical body 15, even if the first rib 33 is embedded in the cylindrical body 15 due to the expansion of the active material inside the cylindrical body 15 after a cycle has elapsed, for example, the first main surface 31a of the base portion 41 and the cylindrical body 15 will be less likely to come into contact. Therefore, oxidation and deterioration of the separator 13 caused by such contact can be suppressed. Thus, it is possible to suppress the occurrence of short circuits in the battery 1.

[0051] In the battery 1, the thickness ratio obtained by dividing the protruding height of the first rib 33 by the thickness of the cylindrical body 15 exceeds 1.3. In this case, a battery 1 with excellent cycle characteristics can be realized.

[0052] In the storage battery 1, multiple first ribs 33 are in contact with the cylindrical body 15. In this case, the first main surface 31a of the base portion 41 is closer to the cylindrical body 15 than in the case where the first ribs 33 are not in contact with the cylindrical body 15, so the above effect of making it difficult for the first main surface 31a of the base portion 41 and the cylindrical body 15 to come into contact is particularly effective.

[0053] In the storage battery 1, the cylindrical body 15 is made up of woven fabric. In this case, the first rib 33 of the base portion 41 is more likely to be embedded in the cylindrical body 15 compared to the case where the cylindrical body 15 is made up of woven fabric, so the above effect of making it difficult for the first main surface 31a of the base portion 41 and the cylindrical body 15 to come into contact is particularly effective.

[0054] The storage battery 1 includes a negative electrode 12 positioned on the opposite side of the positive electrode 10 of the separator 13. The base portion 41 includes a second main surface 31b facing the negative electrode 12. The second main surface 31b is flat. In this case, the separator 13 is more susceptible to oxidation and deterioration compared to the case where ribs are provided on the second main surface 31b, and the above effect of suppressing the occurrence of short circuits is significant.

[0055] In the storage battery 1, the distance between a pair of first ribs 33 adjacent in the second direction Y is smaller than the outer diameter of the cylindrical body 15. In this case, it is possible to suppress the cylindrical body 15 from contacting the first main surface 31a of the base portion 41 without contacting the first ribs 33, and to make it difficult for the first main surface 31a of the base portion 41 and the cylindrical body 15 to come into contact.

[0056] In the battery 1, the first main surface 31a has multiple rib rows RL in the Y direction, each consisting of multiple first ribs 33 arranged in the first direction Z. In a pair of adjacent rib rows RL, the positions of the multiple first ribs 33 in one rib row RL are offset in the first direction Z from the positions of the multiple first ribs 33 in the other rib row RL. This allows for a larger range in the first direction Z on the first main surface 31a where the first ribs 33 exist when viewed from the second direction Y. In other words, when viewed from the second direction Y, the first ribs 33 are more likely to exist at any position in the first direction Z on the first main surface 31a (the probability of the first ribs 33 existing along the first direction Z increases). Therefore, it is possible to enhance the above-mentioned effect of suppressing the occurrence of short circuits.

[0057] In the storage battery 1, the thickness of the cylindrical body 15 is 0.6 mm or less. If the thickness of the cylindrical body 15 exceeds 0.6 mm, the deterioration of battery characteristics due to increased resistance becomes significant, so it is effective for the thickness of the cylindrical body 15 to be 0.6 mm or less.

[0058] In the storage battery 1, the protrusion height of the first rib 33 is 1.5 mm or less. If the protrusion height of the first rib 33 is greater than 1.5 mm, the distance between the electrode plates becomes too large, and the deterioration of battery characteristics (decrease in high-rate discharge characteristics) becomes significant. Therefore, it is effective to keep the protrusion height of the first rib 33 at 1.5 mm or less.

[0059] The method for manufacturing the storage battery 1 is a manufacturing method for manufacturing the storage battery 1, and includes the step of arranging the positive electrode 10 and the separator 13 such that the first main surface 31a of the separator 13 faces the positive electrode 10. In the storage battery 1 manufactured by this manufacturing method, as described above, oxidation and deterioration of the first main surface 31a of the separator 13 can be suppressed, and the occurrence of short circuits can be suppressed.

[0060] Modifications of the above embodiment will now be described. In the following modifications, explanations of parts that overlap with the above embodiment will be omitted.

[0061] Figure 9 is an enlarged plan view showing a part of the electrode group 3A according to the first modified example. Figure 9 shows a cross-section of the electrode group 3A perpendicular to the first direction Z. As shown in Figure 9, the electrode group 3A according to the first modified example includes a separator 13A instead of separator 13 (see Figure 6). The base portion 41A of separator 13A is provided with a plurality of second ribs 34 that protrude from the second main surface 31b toward the negative electrode 12 in the third direction X. The plurality of second ribs 34 are projections that protrude from the second main surface 31b and are configured similarly to the first rib 33. The plurality of second ribs 34 are arranged in a staggered pattern on the second main surface 31b when viewed from the third direction X. At least a portion of the plurality of second ribs 34 are in contact with the negative electrode 12.

[0062] In this first modified example, the same effects and advantages as in the above embodiment are achieved. In addition, in the first modified example, a second rib 34 is provided on the second main surface 31b of the base portion 41A. In this case, the second rib 34 makes it difficult for the negative electrode 12 to come into contact with the second main surface 31b of the separator 13A, thereby suppressing oxidation and deterioration of the separator 13A and further suppressing the occurrence of short circuits.

[0063] The second rib 34 may be a protrusion extending continuously in the first direction Z. Multiple second ribs 34 extending in the first direction Z may be arranged on the first main surface 31a at predetermined intervals in the second direction Y.

[0064] Figure 10(a) is a diagram showing the first main surface side of separator 13B according to the second modified example, and Figure 10(b) is a schematic cross-sectional view along the line Xb-Xb in Figure 10(a). As shown in Figures 10(a) and 10(b), the second modified example includes separator 13B instead of separator 13 (see Figure 7). In separator 13B, the first ribs 33 are arranged in a grid pattern on the first main surface 31a when viewed from the third direction X. In a pair of adjacent rib rows RL, the positions of the multiple first ribs 33 included in one rib row RL and the positions of the multiple first ribs 33 included in the other rib row RL are the same in the first direction Z. In other words, the first ribs 33 included in a certain rib row RL overlap in the first direction Z with respect to the first ribs 33 included in the adjacent rib row RL.

[0065] In this second modified example, the same effects and advantages as in the above embodiment are achieved. In addition, in the second modified example, the positions of the multiple first ribs 33 included in one rib row RL and the positions of the multiple first ribs 33 included in the other rib row RL adjacent to the said rib row RL are at the same position in the first direction Z. As a result, when the multiple cylindrical bodies 15 and the multiple first ribs 33 come into contact, the distance between the multiple cylindrical bodies 15 and the first main surface 31a of the base portion 41 tends to remain constant, thereby enhancing the above effect of suppressing the occurrence of short circuits.

[0066] Figure 11 is a table showing the evaluation test results for the above embodiments and modified examples. In Figure 11, Examples 1 to 5 are examples corresponding to the above embodiments and modified examples, and Comparative Examples are examples that do not correspond to the above embodiments and modified examples. "Cylindrical body thickness" is the thickness of the cylindrical body 15. The thickness of the cylindrical body 15 can be determined, for example, by subtracting the inner diameter from the outer diameter of the cylindrical body 15. For example, the inner diameter of the cylindrical body 15 is the average value obtained by inserting pin gauges of different diameters and measuring the minimum distance randomly 5 times. For example, the outer diameter of the cylindrical body 15 is the average value obtained by measuring 5 random measurement points using a thickness meter when a load is applied.

[0067] "First rib thickness" is the protruding height of the first rib 33. The "width" of "first rib depth" is the dimension of the first rib 33 in the second direction Y. The "length" of "first rib depth" is the dimension of the first rib 33 in the first direction Z. For example, "first rib depth" is the average value of three measurements taken using calipers. "Thickness ratio" is the value obtained by dividing the first rib thickness by the thickness of the cylindrical body. "Base thickness" is the thickness of the base portion 41. "Second rib thickness" is the protruding height of the second rib 34. "None" for second rib thickness means that the second rib 34 is not provided on the second main surface 31b and the second main surface 31b is a flat surface. Here, the second rib 34 is a protrusion that extends continuously in the first direction Z. "Base thickness + second rib thickness" is the sum of the thickness of the base portion 41 and the protruding height of the second rib 34.

[0068] The "size of the gap in the cylindrical body" corresponds to the depth of the recess in the woven fabric that makes up the cylindrical body 15. For example, the "size of the gap in the cylindrical body" is the average value of three values ​​measured using a microscope. The "cycle evaluation" is the evaluation result obtained by performing a test using the test method described in JIS D 5303-1 or a similar test method. A cycle evaluation of "C" means the product is unacceptable. A cycle evaluation of "A", "AA", and "AAA" means the product is acceptable, with the evaluation being in this order from highest to lowest. The measurement methods for each value are not particularly limited, and various known methods can be used.

[0069] As shown in the evaluation test results in Figure 11, the effects of changing each parameter in the above embodiment and modified example can be confirmed. In particular, the thickness of the cylindrical body is preferably greater than 0.2 mm from the viewpoint of durability of the cylindrical body 15. The thickness of the cylindrical body is preferably 0.6 mm or less so as not to worsen the capacitance. The thickness of the first rib is preferably greater than 0.2 mm. The thickness of the first rib is preferably 1.5 mm or less from the viewpoint of not worsening the high-rate discharge characteristics. The thickness ratio is preferably greater than 1.0. The thickness ratio is preferably 5.0 or less from the viewpoint of not worsening the high-rate discharge characteristics. From the viewpoint of excellent cycle characteristics, the thickness ratio is preferably greater than 1.3, more preferably 1.5 or more, more preferably 1.6 or more, more preferably 1.8 or more, more preferably 2.0 or more, more preferably 2.7 or more, more preferably 3.0 or more, more preferably 3.5 or more, and more preferably 4.0 or more.

[0070] While embodiments of the present invention have been described above, the present invention is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0071] In the above embodiments and modifications, the separator 13 is folded in half along the second direction Y, but is not limited to this. For example, depending on the dimensions of the electrode group, the separator may be folded in half along the first direction Z. In the above embodiments and modifications, the separator 13 is a bag-shaped workpiece, but is not limited to this. For example, the separator may be a cylindrical workpiece. In this case, sealing portions may be provided on both sides in the second direction Y, or a sealing portion may be provided on only one side in the second direction Y. Also, for example, the separator may be a workpiece different from the bag-shaped workpiece and the cylindrical workpiece.

[0072] The above embodiments and modifications include, but are not limited to, a plurality of separators 13. For example, a plurality of positive electrodes and a plurality of negative electrodes included in the electrode group may be separated by a single separator folded in an accordion-like manner in the direction of arrangement.

[0073] The various values ​​in the above embodiments and modifications may include manufacturing, measurement, and design errors. In the above embodiments and modifications, a forklift 100 was described as an example of an electric vehicle, but the electric vehicle may be, for example, a golf cart. In the above embodiments and modifications, a configuration in which a battery pack 200 is mounted on the forklift 100 was described as an example, but a storage battery 1 may also be mounted.

[0074] The constituent elements of one embodiment of the present invention are described below. <Invention 1> A positive electrode comprising multiple cylindrical bodies that house the positive electrode material, A separator comprising a base portion including a first main surface facing the positive electrode, and a plurality of first ribs provided on the first main surface of the base portion, The first ribs are arranged in a two-dimensional manner with intervals between them on the first main surface. A lead-acid battery in which the protruding height of the first rib is greater than the thickness of the cylindrical body. <Invention 2> The lead-acid battery according to Invention 1, wherein the thickness ratio obtained by dividing the protruding height of the first rib by the thickness of the cylindrical body is greater than 1.3. <Invention 3> The lead-acid battery according to invention 1 or 2, wherein the cylindrical body is composed of a woven fabric. <Invention 4> The separator is provided with a negative electrode located on the opposite side from the positive electrode side, The base portion includes a second main surface facing the negative electrode, A lead-acid battery according to any one of inventions 1 to 3, wherein the second main surface is provided with a second rib. <Invention 5> The lead-acid battery according to any one of Invention 1 to 4, wherein the thickness of the cylindrical body is 0.6 mm or less. <Invention 6> The lead-acid battery according to any one of inventions 1 to 5, wherein the protruding height of the first rib is 1.5 mm or less. <Invention 7> A method for manufacturing a lead-acid battery as described in any one of Inventions 1 to 6, A method for manufacturing a lead-acid battery, comprising the step of arranging the positive electrode and the separator such that the first main surface of the separator faces the positive electrode. [Explanation of symbols]

[0075] 1... Storage battery (lead-acid battery), 3,3A... Electrode group, 10... Positive electrode, 12... Negative electrode, 14... Current collector, 13,13A,13B... Separator, 15... Cylindrical body, 16... Positive electrode material, 41,41A... Base part, 31a... First main surface, 31b... Second main surface, 33... First rib, 34... Second rib, 100... Forklift (electric vehicle), 200... Battery pack, RL... Rib row, X... Third direction, Y... Second direction, Z... First direction.

Claims

1. A positive electrode comprising multiple cylindrical bodies that house the positive electrode material, A separator comprising a base portion including a first main surface facing the positive electrode, and a plurality of first ribs provided on the first main surface of the base portion, The first ribs are arranged in a two-dimensional manner with intervals between them on the first main surface. The protruding height of the first rib is greater than the thickness of the cylindrical body. A lead-acid battery in which the thickness ratio obtained by dividing the protruding height of the first rib by the thickness of the cylindrical body is greater than 1.

3.

2. The lead-acid battery according to claim 1, wherein the cylindrical body is composed of a woven fabric.

3. The separator is provided with a negative electrode located on the opposite side from the positive electrode side, The base portion includes a second main surface facing the negative electrode, The lead-acid battery according to claim 1 or 2, wherein the second main surface is provided with a second rib.

4. The separator is provided with a negative electrode located on the opposite side from the positive electrode side, The base portion includes a second main surface facing the negative electrode, The lead-acid battery according to claim 1 or 2, wherein the second main surface is a flat surface.

5. The lead-acid battery according to claim 1 or 2, wherein the thickness of the cylindrical body is 0.6 mm or less.

6. The lead-acid battery according to claim 1 or 2, wherein the protruding height of the first rib is 1.5 mm or less.

7. A method for manufacturing a lead-acid battery according to claim 1 or 2, A method for manufacturing a lead-acid battery, comprising the step of arranging the positive electrode and the separator such that the first main surface of the separator faces the positive electrode.

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