Battery separators, storage batteries, battery packs and electric vehicles

Abstract

This cell separator includes a base portion including a first major surface and a second major surface located opposite to the first major surface, and a welded portion extending in a first direction of the base portion to fix a first portion and a second portion of the second major surface. At least one of the first major surface and the second major surface is provided with a first rib and a second rib arranged in a second direction intersecting the first direction, the first and second ribs being spaced apart from each other. The welded portion includes a welded area located between the first rib and the second rib in the second direction. The welded area is spaced from the first rib and the second rib and extends from one end to the other end of the welded portion in the first direction.

Description

[Technical Field]

[0001] The present disclosure relates to a battery separator, a storage battery, a battery pack, and an electric vehicle. [Background technology]

[0002] Batteries use separators to prevent short circuits between the positive and negative electrodes. For example, linear ribs are formed on the outer surface of the separator for a storage battery disclosed in Patent Document 1. In Patent Document 1, the outer surface of the separator and the side surfaces of the ribs are connected by a continuous curved surface to prevent the separator from breaking due to cracks along the base of the ribs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-338274 Summary of the Invention [Problem to be solved by the invention]

[0004] To improve the short-circuit prevention function of the separator, one portion of the separator may be welded to another portion. For example, when welding the separator described in Patent Document 1, not only welds along the extension direction of the ribs but also welds along a direction intersecting the ribs are formed. There is a problem that welds that overlap with ribs provided on the outer surface of the separator are prone to poor fixation of the separator.

[0005] An object of one aspect of the present disclosure is to provide a battery separator, a storage battery, a battery pack, and an electric vehicle that can suppress the occurrence of welding defects even when ribs are formed. [Means for solving the problem]

[0006] A battery separator according to one aspect of the present disclosure comprises a base having a first main surface and a second main surface located opposite the first main surface, and a welded portion extending in a first direction of the base and fixing a first portion and a second portion of the second main surface, wherein at least one of the first main surface and the second main surface is provided with a first rib and a second rib arranged along a second direction intersecting the first direction and spaced apart from each other, and the welded portion has a welded region located between the first rib and the second rib in the second direction, the welded region being spaced apart from the first rib and the second rib and extending continuously from one end to the other end of the welded portion in the first direction.

[0007] In this battery separator, at least one of the first and second main surfaces is provided with a first rib and a second rib arranged along the second direction and spaced apart from each other. This allows the thickness of the base to be reduced while improving the durability of the separator. In addition, the welding region of the welding part is located between the first and second ribs in the second direction. Furthermore, the welding region is spaced apart from the first and second ribs and extends continuously from one end of the welding part to the other end in the first direction. This allows the first and second portions of the second main surface in the welding region to be securely fixed together. Therefore, even when ribs are formed on the battery separator, the occurrence of welding defects can be suppressed.

[0008] At least the second major surface may have a first rib and a second rib.

[0009] The first main surface may have a first rib and a second rib, and the second main surface may have a third rib overlapping the welding area. Even in this case, the first rib and the second rib do not hinder the formation of the welding part, so that the occurrence of poor welding in the welding area can be suppressed.

[0010] The first rib on the first main surface may overlap the first rib on the second main surface, which improves the durability of the separator while effectively reducing the thickness of the base.

[0011] The second rib on the first main surface may overlap the second rib on the second main surface, which improves the durability of the separator while effectively reducing the thickness of the base.

[0012] The welding region may be located between a plurality of first ribs arranged in the first direction and a plurality of second ribs arranged in the first direction, and may be spaced apart from the plurality of first ribs and the plurality of second ribs. In this case, the durability of the separator can be improved by the plurality of first ribs and the plurality of second ribs, and the first portion and the second portion of the second main surface in the welding region can be more effectively fixed together.

[0013] The welded region may extend linearly in the first direction, in which case the welded region can be easily formed by, for example, ultrasonic welding.

[0014] The welded portion may be located between the first rib and the second rib in the second direction and may be spaced apart from the first rib and the second rib, in which case the first and second portions of the second main surface can be more effectively fixed together by the entire welded portion.

[0015] A storage battery according to one aspect of the present disclosure includes positive and negative electrode plates stacked together, a battery separator for preventing short-circuiting between the positive and negative electrode plates, and a battery case for accommodating the battery separator, the negative and positive electrode plates. This storage battery uses the battery separator, which can suppress welding defects. Therefore, short-circuiting between the negative and positive electrode plates stacked together via the battery separator can be effectively suppressed.

[0016] The welded portion may be located on the opposite side of the negative electrode plate from the bottom of the battery case, which prevents damage to the welded portion due to the separator colliding with the bottom when the battery separator is placed in the battery case.

[0017] In the stacking direction of the negative and positive electrode plates, the welded portion overlaps the lug of the positive electrode plate, and the dimension of the welded portion in the first direction may be equal to or greater than the dimension of the lug in the first direction, which effectively prevents short circuits between the lug of the positive electrode plate and the negative electrode plate.

[0018] The battery may be a lead acid battery.

[0019] A battery assembly according to one aspect of the present disclosure includes the storage battery described above. The battery assembly includes a storage battery including the battery separator described above that is capable of suppressing the occurrence of welding defects. Therefore, in the storage battery, it is possible to effectively suppress short circuits between negative and positive electrode plates that are stacked together with the battery separator interposed therebetween.

[0020] An electric vehicle according to one aspect of the present disclosure includes the battery pack described above. The electric vehicle includes a storage battery including the battery separator described above that is capable of suppressing welding defects. Therefore, in the storage battery, short circuits between negative and positive electrode plates stacked together with the battery separator interposed therebetween can be effectively suppressed.

[0021] A battery separator according to another aspect of the present disclosure comprises a base having a first main surface and a second main surface located opposite the first main surface, and a first rib and a second rib provided on at least one of the first main surface and the second main surface, the first rib and the second rib being arranged along a second direction intersecting the first direction of the first main surface and the second main surface and being spaced apart from each other, the base being provided with a welding portion extending along the first direction and fixing the first portion and the second portion of the second main surface, the welding portion having a welding region located between the first rib and the second rib in the second direction, the welding region being spaced apart from the first rib and the second rib and extending continuously from one end of the welding portion to the other end in the first direction.

[0022] In this battery separator, at least one of the first and second main surfaces is provided with a first rib and a second rib arranged along the second direction and spaced apart from each other. This allows the thickness of the base to be reduced while improving the durability of the separator. In addition, the welding region of the welding part is located between the first and second ribs in the second direction. Furthermore, the welding region is spaced apart from the first and second ribs and extends continuously from one end of the welding part to the other end in the first direction. This allows the first and second portions of the second main surface in the welding region to be securely fixed together. Therefore, even when ribs are formed on the battery separator, the occurrence of welding defects can be suppressed. [Effects of the Invention]

[0023] According to one aspect of the present disclosure, it is possible to provide a battery separator, a storage battery, a battery pack, and an electric vehicle that are capable of suppressing the occurrence of welding defects even when ribs are formed. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view showing a part of a storage battery according to an embodiment in a cutaway state. [Figure 2] FIG. 2 is a plan view showing the negative electrode according to the embodiment. [Figure 3] FIG. 3(a) is a plan view showing the separator sheet, and FIG. 3(b) is a schematic end view taken along line IIIa-IIIa in FIG. 3(a). [Figure 4] FIG. 4 is a plan view showing the separator and the negative electrode plate. [Figure 5] FIG. 5 is an enlarged view of the area surrounded by the dashed line shown in FIG. [Figure 6] FIG. 6(a) is a diagram showing a first main surface of a separator sheet according to a first modified example, and FIG. 6(b) is a diagram showing a second main surface of a separator sheet according to the first modified example. [Figure 7] FIG. 7 is a schematic enlarged view showing a part of a separator according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, a preferred embodiment of one aspect of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0026] FIG. 1 is a perspective view showing a part of a storage battery according to this embodiment, with a part cut away. As shown in FIG. 1, the storage battery 1 is, for example, a valve-regulated lead-acid battery. The storage battery 1 is used, for example, as a battery for an automobile, a backup power source used during a power outage, or the main power source for an electric vehicle (or an electric vehicle) such as an electric forklift. In these cases, a battery pack composed of a plurality of storage batteries 1 may be used. For example, the electric vehicle may have a battery pack including a plurality of storage batteries 1. In this embodiment, the storage battery 1 is, for example, a clad-type lead-acid battery equipped with clad electrodes. The storage battery 1 includes an electrode group 3, a positive terminal 5A, a negative terminal 5B, a water supply valve 6, and a case 7.

[0027] The electrode group 3 has a plurality of positive electrodes 10, a plurality of negative electrodes 12, and a plurality of separators 13. In the electrode group 3, the positive electrodes 10 and the negative electrodes 12 are arranged alternately. A separator 13 is interposed between adjacent positive electrodes 10 and negative electrodes 12. Therefore, the positive electrodes 10 are stacked on the negative electrodes 12 with the separator 13 interposed therebetween. In this embodiment, in the electrode group 3, the 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 the "stacking direction").

[0028] The positive electrode 10 is, for example, a clad type positive electrode plate. The positive electrode 10 has a tubular electrode group 14. The tubular electrode group 14 has a plurality of tubular electrodes 15. The plurality of tubular electrodes 15 are arranged in a row. Each of the plurality of tubular electrodes 16 has, for example, a clad tube, a core metal inserted into the clad tube, and a positive electrode material filled between the clad tube and the core metal. The clad tube is a cylindrical porous tube also called a gauntlet, and is formed, for example, from glass, resin, or the like. The positive electrode material may include a positive electrode active material and an additive. Examples of the positive electrode active material include lead powder, red lead, etc. Examples of the additive include a carbon material or short reinforcing fibers, etc. The positive electrode active material after chemical formation is, for example, lead dioxide, etc.

[0029] FIG. 2 is a plan view showing a negative electrode according to an embodiment. The negative electrode 12 is a negative electrode plate having a negative electrode grid 12a and tabs 12b. The negative electrode grid 12a is provided with a negative electrode material 12c. The negative electrode material may contain a negative electrode active material and an additive. The negative electrode active material is, for example, spongy lead. Examples of the additive include barium sulfate, a carbon material, or short reinforcing fibers. The tabs 12b are terminals that protrude from the negative electrode grid 12a. The negative electrode grid 12a is provided with protrusions 12d and 12e. The protrusions 12d and 12e are arranged at a predetermined interval and are legs that protrude outward from the negative electrode grid 12a. The protrusions 12d and 12e protrude in a direction opposite to the protrusion direction of the tabs 12b. In this embodiment, the protruding direction of the ears 12b and the protruding directions of the protrusions 12d and 12e are perpendicular to the arrangement direction, and the ears 12b and the negative electrode grid 12a do not overlap with each other in the arrangement direction.

[0030] Each positive electrode 10 is electrically connected to a 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 strap 17 is connected to the ear 10a of the positive electrode 10. Each negative electrode 12 is electrically connected to a 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 strap 18 is connected to the ear 12b of the negative electrode 12.

[0031] The separator 13 is a battery component (battery separator) for preventing short-circuiting between the positive electrode 10 and the negative electrode 12. The separator 13 is not particularly limited as long as it is a component that electronically insulates the positive electrode 10 from the negative electrode 12 while allowing ions to pass between them 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 substances. The structure of the separator 13 will be described later.

[0032] The case 5 has a main body 20 and a lid 22. The main body 20 is a box-shaped battery container. The main body 20 is made of a material such as polypropylene. The main body 20 is composed of four side portions 20a and a bottom portion 20b. The main body 20 contains the electrode group 3 and the electrolyte. The lid 22 covers the opening of the main body 20. The lid 22 is provided with a positive electrode terminal 5A, a negative electrode terminal 5B, and a refill tap 6. The refill tap 6 is provided between the positive electrode terminal 5A and the negative electrode terminal 5B.

[0033] Next, the structure of the separator used in this embodiment will be described with reference to Figures 3(a) and 3(b), 4, and 5. First, the structure of a separator sheet, which is a pre-processed product of the separator 13, will be described with reference to Figures 3(a) and 3(b). Figure 3(a) is a plan view showing the separator sheet, and Figure 3(b) is a schematic end view taken along line IIIa-IIIa in Figure 3(a). As shown in Figures 3(a) and 3(b), the separator sheet 30 has a main body portion 31, a pair of edge portions 32, 33, and a plurality of ribs 34.

[0034] The main body portion 31 is a flexible sheet-like portion that constitutes the main portion of the separator sheet 30. The main body portion 31 has a first main surface 31a and a second main surface 31b. Within the separator sheet 30, the second main surface 31b is located on the opposite side of the first main surface 31a in the thickness direction of the separator sheet 30. In this embodiment, the first main surface 31a and the second main surface 31b have a rectangular shape when viewed in the thickness direction of the separator sheet 30, but this is not limited thereto. Hereinafter, the direction of the short side of the main body portion 31 when viewed in the thickness direction of the separator sheet 30 is referred to as the first direction X, and the direction of the long side of the main body portion 31 is referred to as the second direction Y. Also, below, the thickness direction of the separator sheet 30 is referred to as the third direction Z. In this embodiment, the second direction Y corresponds to the direction in which the electrode group 3 is housed in the case 5, and the third direction Z corresponds to the arrangement direction. Furthermore, the first direction X and the second direction Y are perpendicular to each other, but this is not limited thereto. The first direction X and the second direction Y may intersect with each other.

[0035] The pair of edges 32, 33 are provided at both ends of the separator sheet 30 in the first direction X. Each of the edges 32, 33 extends from one end to the other end of the separator sheet 30 in the second direction Y. One end of the separator sheet 30 in the second direction Y corresponds, for example, to the upper end of the paper in FIG. 3A. The other end of the separator sheet 30 in the second direction Y corresponds, for example, to the lower end of the paper in FIG. 3A. Each of the edges 32, 33 may extend continuously or intermittently. The edge 32 is provided at one end in the first direction X, and the edge 33 is provided at the other end in the first direction X. One end in the first direction X corresponds, for example, to the left end of the paper in FIG. 3A. The other end in the first direction X corresponds, for example, to the right end of the paper in FIG. 3A. In this embodiment, the pair of edge portions 32, 33 are not provided with the rib 34, but this is not limiting. At least one of the pair of edge portions 32, 33 may be provided with a rib different from the rib 34. For example, at least one of the pair of edge portions 32, 33 may be provided with one or more ribs or the like extending from one end to the other end in the second direction Y.

[0036] A plurality of ribs 34 are provided on each of the first main surface 31a and the second main surface 31b. In this embodiment, the ribs 34 provided on the first main surface 31a and the ribs 34 provided on the second main surface 31b have the same shape and completely overlap each other. For this reason, hereinafter, only the plurality of ribs 34 provided on the first main surface 31a will be described, and a description of the plurality of ribs 34 provided on the second main surface 31b will be omitted.

[0037] The multiple ribs 34 are provided, for example, to improve the durability of the separator sheet 30 and the fluidity of the electrolyte solution within the case 5. The multiple ribs 34 protrude from the main body 31 along the third direction Z and are spaced apart from one another. Each of the multiple ribs 34 has a rectangular shape when viewed from the third direction Z. In this embodiment, each of the multiple ribs 34 extends linearly and inclined with respect to the first direction X and the second direction Y when viewed from the third direction Z. A cross section of the rib 34 perpendicular to the extension direction of the rib 34 has a rectangular shape, but is not limited to this. The cross section may be, for example, a trapezoidal shape or an inverted trapezoidal shape. The multiple ribs 34 include multiple first ribs 35 and multiple second ribs 36.

[0038] The first ribs 35 and the second ribs 36 are arranged along the second direction Y. They are provided on the first main surface 31a. The first ribs 35 provided on the first main surface 31a overlap the first ribs 35 provided on the second main surface 31b. The second ribs 36 provided on the first main surface 31a overlap the second ribs 36 provided on the second main surface 31b. In this embodiment, a first rib group 37 including a plurality of first ribs 35 and a second rib group 38 including a plurality of second ribs 36 are arranged alternately along the second direction Y. In the first rib group 37, the plurality of first ribs 35 are arranged along the first direction X. Similarly, in the second rib group 38, the plurality of second ribs 36 are arranged along the first direction X. A gap S is provided between the first rib group 37 and the second rib group 38. From the viewpoint of maintaining the performance of the separator sheet 30, the dimension of the gap S along the second direction Y is, for example, 5% to 200% of the dimension of the rib 34 along the second direction Y. The lower limit of the dimension of the gap S may be 10%, 15%, or 20%. The upper limit of the dimension of the gap S may be 150%, 120%, or 100%. Furthermore, from the viewpoint of favorably forming a welded portion 44 (see FIG. 4), which will be described later, during mass production of the separator 13, for example, the dimension of the gap S along the second direction Y is, for example, 1 mm or more.

[0039] The first rib 35 and the second rib 36 extend to intersect with each other. In this embodiment, the first rib 35 extends from one end to the other end in the first direction X as it moves from one end to the other end in the second direction Y. The second rib 36 extends from the other end to one end in the first direction X as it moves from one end to the other end in the second direction Y. Therefore, in this embodiment, a fishbone structure is formed by the first rib 35 and the second rib 36 adjacent to each other in the second direction Y. When viewed from the third direction Z, the angle θ1 between the first rib 35 and the first direction X is, for example, greater than 90° and less than 150°. When viewed from the third direction Z, the angle θ2 between the second rib 36 and the first direction X is, for example, greater than 90° and less than 90°.

[0040] The interval between adjacent first ribs 35 in the first rib group 37 and the interval between adjacent second ribs 36 in the second rib group 38 are the same, but are not limited to this.

[0041] Next, the structure of the separator included in the electrode assembly will be described in detail with reference to Figures 4 and 5. Figure 4 is a plan view showing the separator and the negative electrode plate. Figure 5 is an enlarged view of the area surrounded by the dashed line shown in Figure 4.

[0042] In this embodiment, as shown in FIG. 4 , the separator 13 corresponds to a pouch-shaped product of the separator sheet 30 and encases the negative electrode 12. The separator 13 is formed, for example, by the following method. First, one separator sheet 30 is folded in half along the second direction Y so that the second main surface 31b is located inside. Then, desired locations on the separator sheet 30 are sealed to form the separator 13. At this time, the separator sheet 30 is folded in half so that the negative electrode 12 is sandwiched between the second main surface 31b. Therefore, in the electrode group 3, the positive electrode 10 (see FIG. 1 ) faces the first main surface 31a of the separator sheet 30, and the negative electrode 12 faces the second main surface 31b of the separator sheet 30. From the viewpoint of improving workability, the separator sheet 30 may be folded in half as the negative electrode 12 is moved. At least a portion of the edge portion 12b of the negative electrode 12 is exposed from the separator 13.

[0043] The separator 13 has a base 41, a pair of seal portions 42 and 43, and a welded portion 44. The base 41 accommodates the negative electrode grid 12a and the protrusions 12d and 12e of the negative electrode 12. The base 41 is composed of the main body 31 of the separator sheet 30. The base 41 has a main portion 41a and a bent portion 41b. The bent portion 41b is a folded portion of the separator sheet 30 and can abut against the protrusions 12d and 12e. An opening 45 is provided in a portion of the bent portion 41b. The opening 45 is provided, for example, to improve the fluidity of the electrolyte in the separator 13. The opening 45 is provided, for example, in the center of the separator 13 in the first direction X, but is not limited thereto. The opening 45 may be located anywhere in the separator 13 as long as it does not overlap the protrusions 12d and 12e in the second direction Y. In other words, the opening 45 may be provided so as to prevent the protruding portions 12d and 12e from being exposed from the separator 13. For example, the opening 45 is formed by cutting a part of the bent portion 41b.

[0044] The pair of seal portions 42, 43 are portions for maintaining the separator sheet 30 folded in half. The seal portion 42 is formed on the edge portion 32 (see FIG. 3), and the seal portion 43 is formed on the edge portion 33 (see FIG. 3). Each of the seal portions 42, 43 extends from one end to the other end in the second direction Y. This allows the seal portions 42, 43 to suppress movement of the negative electrode 12 along the first direction X. The seal portions 42, 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 seal portions 42, 43 may have an area through which the electrolyte can pass. The seal portions 42, 43 are, for example, ultrasonic welded portions, heat sealed portions, cold sealed portions, gear sealed portions, etc. The gear sealed portion is a portion that is mechanically bonded by pressure using a gear.

[0045] Similar to the seal portions 42 and 43, the weld portion 44 is a portion for maintaining the state of the separator sheet 30 folded in half. The weld portion 44 is a portion for fixing a portion (first portion) of the second main surface 31b of the separator sheet 30 to another portion (second portion). The first portion and the other portion do not overlap with the negative electrode 12 in the third direction Z and are located on the opposite side of the bent portion 41b in the second direction Y. That is, the weld portion 44 is located on one end side of the separator 13 in the second direction Y and on the outer side of the negative electrode 12 as viewed from the third direction Z. The weld portion 44 also faces the edge portion 12b in the first direction X. Therefore, the weld portion 44 in the case 5 is located on the opposite side of the bottom portion 20b of the main body 20 (battery case) across the negative electrode 12. The weld portion 44 extends along the first direction X. Specifically, the welded portion 44 extends from one end to the other end in the first direction X. Therefore, the welded portion 44 is provided in the base portion 41 and the seal portion 42. The welded portion 44 is, for example, a portion where the separator sheet 30 itself is welded. From the viewpoint of preventing poor welding, the welded portion 44 may be formed by ultrasonic welding or the like. The welded portion 44 may be provided after the seal portions 42, 43 are formed, or may be provided before the seal portions 42, 43 are formed.

[0046] As shown in FIG. 5 , the welded portion 44 has a welded region WR located between the first rib 35 and the second rib 36 in the second direction Y. The welded region WR extends continuously from one end of the welded portion 44 to the other end in the first direction X. The welded region WR is located between the first rib group 37 and the second rib group 38 that are adjacent in the second direction Y. In addition, the welded region WR is spaced apart from both the multiple first ribs 35 provided on the first main surface 31 a and the second main surface 31 b and the multiple second ribs 36 provided on the first main surface 31 a and the second main surface 31 b. That is, the welded portion 44 (welded region WR) is located in the gap S. In this embodiment, the entire welded portion 44 corresponds to the welded region WR and extends linearly along the first direction X. Therefore, the welded portion 44 is located between the first rib 35 and the second rib 36 adjacent to each other in the second direction Y, and is spaced apart from the first rib 35 and the second rib 36.

[0047] In the electrode group 3, the welded portion 44 faces the ear portion 10a of the positive electrode 10 in the arrangement direction (not shown). In addition, the dimension of the welded portion 44 in the first direction X is equal to or greater than the dimension of the ear portion 10a. In this embodiment, both ends of the ear portion 10a in the first direction X are located more inward than both ends of the welded portion 44 in the first direction X. This makes it less likely for the ear portion 10a and the negative electrode 12 to short-circuit.

[0048] In the separator 13 according to the present embodiment described above, at least one of the first main surface 31a and the second main surface 31b is provided with the first rib 35 and the second rib 36 arranged along the second direction Y and spaced apart from each other. This allows the thickness of the main body 31 to be reduced while improving the durability of the separator 13. This improves the performance of a storage battery 1 using the separator 13. In addition, the welded region WR of the welded portion 44 is located between the first rib 35 and the second rib 36 in the second direction Y. Furthermore, the welded region WR is spaced apart from the first rib 35 and the second rib 36 and extends continuously from one end of the welded portion 44 to the other end in the first direction X. This makes it less likely that the first rib 35 and the second rib 36 will hinder the formation of the welded region WR. This allows a portion of the second main surface 31b to be securely fixed to the other portion in the welded region WR. Therefore, according to this embodiment, even when a plurality of ribs 34 are formed on the separator 13, it is possible to prevent the occurrence of welding defects.

[0049] In this embodiment, the first ribs 35 on the first main surface 31a overlap the first ribs 35 on the second main surface 31b, and the second ribs 36 on the first main surface 31a overlap the second ribs 36 on the second main surface 31b. This allows the thickness of the main body 31 to be effectively reduced while improving the durability of the separator 13.

[0050] In this embodiment, the welded region WR is located between the plurality of first ribs 35 arranged in the first direction X and the plurality of second ribs 36 arranged in the first direction X, and is spaced apart from the plurality of first ribs 35 and the plurality of second ribs 36. Therefore, the plurality of first ribs 35 and the plurality of second ribs 36 can improve the durability of the separator 13, and can more effectively fix one portion of the second main surface 31b to the other portion in the welded region WR.

[0051] In this embodiment, the welded region WR extends linearly along the first direction X. Therefore, the welded region WR can be easily formed by, for example, ultrasonic welding or the like.

[0052] In the present embodiment, the welded portion 44 is located between the first rib 35 and the second rib 36 in the second direction Y, and is spaced apart from the first rib 35 and the second rib 36. This allows the welded portion 44 to more effectively fix one portion of the second main surface 31b to the other portion of the second main surface 31b throughout the entire welded portion 44.

[0053] By using a storage battery 1 that uses the separator 13 according to this embodiment, it is possible to effectively prevent short circuits between the positive electrode 10 and the negative electrode 12 that are stacked together with the separator 13 interposed therebetween. Therefore, according to this embodiment, it is possible to realize a storage battery 1 that is less likely to suffer from short circuit defects. In addition, in this embodiment, the welded portion 44 is located on the opposite side of the negative electrode 12 from the bottom 20b of the main body 20 in the second direction Y. Therefore, when the electrode group 3 including the separator 13 is housed in the main body 20, damage to the welded portion 44 due to collision of the separator 13 with the bottom 20b can be prevented.

[0054] Modifications of the above embodiment will be described below with reference to Figures 6 and 7. In the following modifications, explanations of points that overlap with the above embodiment will be omitted. Therefore, the following will mainly describe points that are different from the above embodiment.

[0055] FIG. 6A shows the first main surface of a separator sheet according to a first modified example, and FIG. 6B shows the second main surface of the separator sheet according to the first modified example. As shown in FIGS. 6A and 6B, in a separator sheet 30A according to the first modified example, the shape of the plurality of ribs 34A (third ribs) formed on the second main surface 31b differs from that of the above-described embodiment. Specifically, as shown in FIG. 6B, the second main surface 31b is provided with a plurality of ribs 34A extending linearly along the second direction Y. Each rib 34A extends continuously from one end to the other end in the second direction Y. Therefore, each rib 34A overlaps with the ribs 34 (first rib 35 and second rib 36) provided on the first main surface 31a, at a gap S. The ribs 34 provided on the first main surface 31a overlap with portions of the ribs 34A provided on the second main surface 31b.

[0056] When a pouch-shaped product similar to the separator 13 according to the above embodiment is formed from the separator sheet 30A, the welded portion is provided in the gap S between the first rib group 37 and the second rib group 38 on the first main surface 31a (see FIG. 4). Therefore, in the first modified example, the welded portion overlaps a part of the rib 34A.

[0057] In the first modified example described above, the welded portion is formed by, for example, ultrasonic welding. For this purpose, an ultrasonic welding device including a horn that contacts the separator is used. The horn contacts a portion of the first main surface 31a where the ribs 34 are not provided. That is, the horn contacts a flat surface of the separator sheet 30A. Therefore, in the first modified example, the formation of the welded portion is not hindered by the ribs 34 (first rib 35 and second rib 36) provided on the first main surface 31a. Therefore, the first modified example can also achieve the same effects as the above embodiment.

[0058] FIG. 7 is a schematic enlarged view showing a portion of a separator according to a second modified example. As shown in FIG. 7, in the second modified example, a welded portion 44A is formed in the region where the rib 34 is to be formed. Specifically, a portion of the welded portion 44A overlaps the region of the first main surface 31a where the first rib 35 was formed. The welded portion 44A has a welded region WR1 provided in the region of the first main surface 31a where the first rib 35 is not formed. As in the above embodiment, the welded region WR1 is located between the adjacent first rib 35 and second rib 36 in the second direction Y and is spaced apart from the rib 34 (the first rib 35 and the second rib 36). Additionally, as in the above embodiment, the welded region WR1 extends continuously from one end to the other end of the welded portion 44A in the first direction X.

[0059] From the viewpoint of the fixing strength of the welded portion 44A, the ratio of the width H2 of the welded region WR1 to the width H1 of the welded portion 44A in the second direction Y is, for example, 5% or more. The ratio of the width H2 may be 10% or more, 20% or more, 30% or more, 50% or more, 60% or more, or 70% or more. From the viewpoint of strengthening the fixing strength of the welded portion 44A, the ratio of the width H2 may be 50% or more. The width H2 may be the minimum width or the average width of the welded region WR1. When the width H2 is the average width of the welded region WR1, the minimum width and the maximum width of the welded region WR1 in the second direction Y are, for example, 0.5 to 1.5 times the average width.

[0060] In the second modified example described above, the welded portion 44A has the welded region WR1, and thus the same effects as those of the above embodiment can be achieved.

[0061] The separator according to one aspect of the present disclosure is not limited to the above embodiment and the above modification. The above embodiment and the above modification may be combined as appropriate. For example, a portion of the welded portion may overlap the area where the rib was formed on the first main surface and the area where the rib was formed on the second main surface.

[0062] In the above embodiment and modified example, the storage battery is a clad lead-acid battery having clad electrodes, but is not limited to this. For example, the storage battery does not need to have clad electrodes. In this case, the positive electrode of the storage battery may have the same shape as the negative electrode, for example. Furthermore, the storage battery may be, for example, a valve-regulated lead-acid battery.

[0063] In the above embodiment and modified example, the separator sheet is folded in half along the second direction, but this is not limited to this. For example, depending on the dimensions of the electrode group, the separator sheet may be folded in half along the first direction. In this case, an opening does not need to be provided at the bent portion of the separator.

[0064] In the above embodiment and modified example, the separator is a bag-shaped product, but is not limited thereto. For example, the separator may be a cylindrical product. In this case, the welded portion may be provided on both sides in the second direction, or on only one side in the second direction. For example, the welded portion may be provided only on the opposite side of the negative electrode current collecting tab across the negative electrode plate in the second direction.

[0065] In the above embodiment and modified example, the separator is formed from a single separator sheet, but this is not limited thereto. For example, the separator may be formed from multiple separator sheets. In this case, seals may be formed on both ends of the separator in the first direction, or on only one side in the first direction. Furthermore, welds may be formed on both sides of the separator in the second direction, or on only one side in the second direction. Therefore, when the separator is formed from multiple separator sheets, the separator may be a bag-shaped product, a cylindrical product, or a product different from a bag-shaped product or a cylindrical product. When the welds are provided on the opposite side of the negative electrode current collector tab across the negative electrode plate in the second direction, the welds may be provided so as to face the protrusions of the negative electrode plate in the second direction. In this case, the protrusions are less likely to be exposed from the separator, making short circuits less likely to occur. When the welded portion is provided so as to face the protrusion of the negative electrode plate in the second direction, the dimension of the welded portion in the first direction may be larger than the dimension of the protrusion in the first direction, which makes it difficult for the protrusion to be satisfactorily exposed from the separator.

[0066] In the above embodiment and modified example, the battery case includes multiple separators, but this is not limited thereto. For example, the multiple positive electrode plates and multiple negative electrode plates included in the electrode assembly may be separated by a single separator sheet. In this case, for example, the separator sheet is folded in an accordion shape in the arrangement direction. In the electrode assembly, the positive electrode plates are arranged so as to be sandwiched between the first main surface of the accordion-shaped separator sheet, and the negative electrode plates are arranged so as to be sandwiched between the second main surface of the separator sheet. By providing a welding portion in part of the separator sheet, it is possible to suppress misalignment between the separator sheet and the positive electrode plates and the negative electrode plates. In this case, the manufacturing cost of the electrode assembly can be reduced.

[0067] In the above embodiment and modified example, the ribs extend linearly when viewed from the third direction, but this is not limited thereto. For example, the ribs may extend in a wavy line or a zigzag pattern when viewed from the third direction. Furthermore, the ribs may be dot-shaped, circular, elliptical, or polygonal when viewed from the third direction. Alternatively, the ribs may be polygonal pyramidal, truncated polygonal pyramidal, conical, or truncated conical. The cross section of the rib may be semicircular or polygonal. The ribs may extend along the first direction or along the second direction.

[0068] In the above embodiment and modified example, the ribs provided on the first main surface overlap at least a portion of the ribs provided on the second main surface, but this is not limited to this. For example, the ribs provided on the first main surface and the ribs provided on the second main surface do not have to overlap each other. Furthermore, the multiple first ribs included in the first rib group are arranged along the first direction, but this is not limited to this. For example, the multiple first ribs may be arranged in a direction intersecting the second direction. Similarly, the multiple second ribs may be arranged in a direction intersecting the second direction. The first ribs and the second ribs are arranged along the second direction, but this is not limited to this. For example, the first ribs and the second ribs may be arranged in a direction intersecting the first direction. Note that the first ribs and the second ribs may extend parallel to each other when viewed from the third direction.

[0069] In the above embodiment and modified example, the welded region extends linearly, but this is not limited thereto. The welded region may extend continuously from one end of the welded portion in the first direction to the other. For example, the welded region may extend in a wavy line or a zigzag pattern. [Explanation of symbols]

[0070] 1...storage battery, 3...electrode group, 5A...positive electrode terminal, 5B...negative electrode terminal, 7...case, 10...positive electrode (positive electrode plate), 10a...lug portion, 12...negative electrode (negative electrode plate), 12a...negative electrode grid, 12b...lug portion, 12d, 12e...protrusion (foot portion), 13...separator, 20...main body, 22...lid, 30, 30A...separator sheet, 31...main body portion, 31 a...first main surface, 31b...second main surface, 32, 33...edge portion, 34...rib, 34A...rib (third rib), 35...first rib, 36...second rib, 37...first rib group, 38...second rib group, 41...base portion, 41a...main portion, 41b...bending portion, 42, 43...seal portion, 44, 44A...welded portion, 45...opening, WR, WR1...welded area.

Claims

1. a base having a first major surface and a second major surface opposite the first major surface; a weld portion extending in a first direction of the base portion and fixing the first portion and the second portion of the second main surface; Equipped with At least one of the first main surface and the second main surface is provided with a first rib and a second rib that are arranged along a second direction intersecting the first direction and are spaced apart from each other, the welded portion has a welded region located between the first rib and the second rib in the second direction, the welded region is spaced apart from the first rib and the second rib and extends continuously from one end of the welded portion to the other end in the first direction. Battery separator.

2. The battery separator according to claim 1 , wherein at least the second main surface has the first rib and the second rib.

3. the first main surface has the first rib and the second rib, The battery separator according to claim 1 , wherein the second main surface has a third rib that overlaps the welded region.

4. The battery separator according to claim 1 , wherein the first rib on the first main surface overlaps the first rib on the second main surface.

5. The battery separator according to claim 1 , wherein the second rib on the first main surface overlaps the second rib on the second main surface.

6. 6. The battery separator according to claim 1, wherein the welded region is located between a plurality of the first ribs arranged in the first direction and a plurality of the second ribs arranged in the first direction, and is spaced apart from the plurality of the first ribs and the plurality of the second ribs.

7. The battery separator according to claim 1 , wherein the welded region extends linearly along the first direction.

8. The battery separator according to any one of claims 1 to 7, wherein the welded portion is located between the first rib and the second rib in the second direction and is spaced apart from the first rib and the second rib.

9. a positive electrode plate and a negative electrode plate stacked on top of each other; The battery separator according to any one of claims 1 to 8, which prevents short-circuiting between the positive electrode plate and the negative electrode plate; a battery case that accommodates the positive electrode plate, the negative electrode plate, and the battery separator; A storage battery.

10. The storage battery according to claim 9 , wherein the welded portion is located on the opposite side of the bottom of the battery case across the negative electrode plate.

11. In the stacking direction of the negative electrode plate and the positive electrode plate, the welded portion overlaps with an ear portion of the positive electrode plate, The storage battery according to claim 9 or 10, wherein a dimension of the welded portion in the first direction is equal to or greater than a dimension of the lug portion in the first direction.

12. The battery according to any one of claims 9 to 11, which is a lead acid battery.

13. A battery pack comprising the storage battery according to any one of claims 9 to 12.

14. An electric vehicle comprising the battery pack according to claim 13.

15. a base having a first major surface and a second major surface opposite the first major surface; a first rib and a second rib provided on at least one of the first main surface and the second main surface; Equipped with the first rib and the second rib are arranged along a second direction intersecting the first direction of the first main surface and the second main surface, and are spaced apart from each other; a welding portion extending along the first direction and fixing the first portion and the second portion of the second main surface to each other is provided on the base portion; the welded portion has a welded region located between the first rib and the second rib in the second direction, the welded region is spaced apart from the first rib and the second rib and extends continuously from one end of the welded portion to the other end in the first direction; Battery separator.

Images