JP7689426B2 - Battery plate group, storage battery, battery pack, electric vehicle, and method of manufacturing battery plate group - Google Patents

Description

The present invention relates to a battery plate group, a storage battery, a battery pack, an electric vehicle, and a method for manufacturing a battery plate group.

A separator is used in a battery to prevent short circuits between the positive and negative electrodes. For example, the following Patent Document 1 discloses a method for manufacturing an electrode plate containing a pouched separator. In the following Patent Document 1, the separator is folded to sandwich an electrode plate having an active material. In addition, a pouched separator is formed by forming a plurality of welded portions on the separator. Also, a cut is provided in the folded portion of the separator. The above cut and the unwelded portion of the separator allow the electrolyte to flow and diffuse between the separator and the electrode plate. In addition, if gas is generated from the electrode plate during charging of the battery, the gas can also flow and diffuse.

Patent No. 4661423

Active material may detach from the electrode plate due to vibration of the device in which the battery is mounted, flow of the electrolyte, etc. Some of the detached active material may fall onto the electrode plate exposed from the unwelded part of the separator, for example. In this case, the fallen active material may become a conductive path, causing a short circuit between the electrode plates.

To prevent such short circuits, for example, the welded portion of the separator can be enlarged to reduce the area where the electrode plate is exposed. However, simply enlarging the welded portion impedes the flow and diffusion of the electrolyte between the separator and the electrode plate. Furthermore, if gas is generated from the electrode plate during charging of the battery, the flow and diffusion of the gas is also impeded.

The objective of one aspect of the present invention is to provide a battery plate group, a storage battery, a battery pack, an electric vehicle, and a method for manufacturing a battery plate group that can suppress short circuits caused by the accumulation of active materials while maintaining the diffusibility of an electrolyte solution, etc.

A battery plate group according to one aspect of the present invention includes a first plate and a second plate stacked together in a first direction, and a separator located between the first plate and the second plate. The first plate has a first body portion and a first current collector including a first ear portion protruding from an outer edge of the first body portion in a second direction perpendicular to the first direction, and an insulating structure covering at least a part of the outer edge when viewed from the second direction. The second plate has a second body portion and a second current collector including a second ear portion protruding from the second body portion in the second direction, and at least a part of the second ear portion overlaps the insulating structure in the first direction, and a part of the second plate is covered by the separator when viewed from the second direction.

In this battery plate group, the second ear of the second current collector included in the second plate overlaps with the insulating structure that covers at least a part of the outer edge of the first plate in the first direction. As a result, when viewed from the second direction, the insulating structure is provided on the shortest path along the first direction between the second ear and the first plate. For this reason, for example, when the battery plate group is contained in a battery container together with an electrolyte, and the active material of the first plate and/or the second plate accumulates on the second ear, a short circuit between the first plate and the second ear via the shortest path is inhibited by the insulating structure. In addition, when viewed from the second direction, a part of the second plate is covered by the separator. As a result, a short circuit between the first plate and the second plate via the part of the second plate is also inhibited by the separator. In addition, because another part of the second plate is not covered by the separator, the flow and diffusion of the electrolyte between the second plate and the separator are not easily hindered by the separator. Therefore, according to one aspect of the present invention, it is possible to suppress short circuits caused by the accumulation of active material while maintaining the diffusibility of the electrolyte.

The insulating structure may have an opening that exposes a portion of the first current collector when viewed from the second direction. In this case, accumulation of electrolyte or the like between the first electrode plate and the insulating structure can be suppressed.

The opening may overlap a portion of the second plate that is covered by the separator in the first direction. In this case, the separator is provided on the shortest path between the opening and the second plate along the first direction when viewed from the second direction. Therefore, even if active material accumulates in the opening, a short circuit between the first plate and the second plate using the active material as a conductive path is likely to be inhibited by the separator.

The opening may be located on the opposite side of the first ear portion through the center of the first plate when viewed from the second direction.

The insulating structure has a main portion that covers at least a portion of the outer edge when viewed from the second direction, and a protruding portion that protrudes from the main portion in the second direction, and the thickness of the protruding portion along the first direction may be smaller than the thickness of the main portion along the first direction. In this case, the active material is less likely to accumulate on the main portion due to the protruding portion oscillating in association with, for example, the flow of the electrolyte.

The tip of the protrusion may have an uneven shape. In this case, active material is less likely to accumulate on the tip of the protrusion.

The first main body portion has a first core, a second core, and a connecting portion that connects the first core and the second core and includes an outer edge, and the first electrode plate may further have a first cylindrical body into which the first core is inserted, a second cylindrical body into which the second core is inserted, and a positive electrode active material filled into each of the first cylindrical body and the second cylindrical body. In this case, detachment of the positive electrode active material from the first core and the second core is suppressed by the first cylindrical body and the second cylindrical body.

The insulating structure may seal one end of the first cylindrical body and one end of the second cylindrical body. In this case, the positive electrode active material is preferably prevented from leaking out of the first cylindrical body and the second cylindrical body.

A storage battery according to one aspect of the present invention includes the battery plate group and a battery case in which the battery plate group is housed. When the active material of the first plate and/or the second plate accumulates on the second ear when the storage battery is filled with electrolyte, the insulating structure prevents a short circuit between the first plate and the second ear via the shortest path between the second ear and the first plate along the first direction. In addition, a part of the second plate is covered by the separator when viewed from the second direction. As a result, a short circuit between the first plate and the second plate via the part of the second plate is also prevented by the separator. In addition, another part of the second plate is not covered by the separator, so that the flow, diffusion, etc. of the electrolyte between the second plate and the separator is less likely to be hindered by the separator.

The storage battery may be a lead-acid battery. In this case, even if gas is generated from the second plate, the gas is less likely to accumulate.

A battery pack according to one aspect of the present invention includes the above-described storage battery. This battery pack includes a storage battery including a battery plate group that can suppress short circuits caused by the accumulation of active material while maintaining the diffusibility of the electrolyte and the like. Therefore, in the storage battery, it is possible to effectively suppress short circuits between the first plate and the second plate caused by the accumulation of active material.

An electric vehicle according to one aspect of the present invention includes the above-mentioned battery pack. This electric vehicle includes a storage battery including a battery plate group that can suppress short circuits caused by the accumulation of active material while maintaining the diffusibility of the electrolyte and the like. Therefore, in the storage battery, it is possible to effectively suppress short circuits between the first and second plates caused by the accumulation of active material.

A method for manufacturing a battery plate group according to one aspect of the present invention is a method for manufacturing the battery plate group, and includes a step of stacking the first plate and the second plate so that the second ear overlaps the insulating structure in the first direction. As a result, when viewed from the second direction, the insulating structure is provided on the shortest path along the first direction between the second ear and the first plate. Therefore, for example, when the battery plate group is contained in a battery container together with an electrolyte, and the active material of the first plate and/or the second plate accumulates on the second ear, a short circuit between the first plate and the second ear via the shortest path is prevented by the insulating structure.

According to one aspect of the present invention, it is possible to provide a battery plate group, a storage battery, a battery pack, an electric vehicle, and a method for manufacturing a battery plate group that can suppress short circuits caused by the accumulation of active materials while maintaining the diffusibility of an electrolyte solution, etc.

FIG. 1 is a perspective view showing a part of a storage battery according to an embodiment of the present invention in a cutaway state. FIG. 2 is a cross-sectional view of a portion of the electrode assembly. FIG. 3( a ) is a diagram showing the positive electrode as viewed from a first direction, and FIG. 3( b ) is a diagram showing a part of the positive electrode as viewed from the first direction. FIG. 4( a ) is a schematic diagram showing the positive electrode as viewed from a second direction, and FIG. 4( b ) is a schematic diagram showing a part of the positive electrode as viewed from a third direction. FIG. 5 is a plan view showing the negative electrode according to the embodiment. 6(a) is a plan view showing a separator sheet, and FIG. 6(b) is a schematic cross-sectional view taken along line VIb-VIb in FIG. 6(a). FIG. 7 is a plan view showing the negative electrode wrapped in a separator. FIG. 8 is an enlarged view of the main parts of the electrode plate group and each strap. FIG. 9 is a schematic diagram of a main portion showing a state in which the positive electrode and the negative electrode are laminated. FIG. 10 is a plan view showing a negative electrode wrapped in a separator according to a first modified example. FIG. 11 is a schematic plan view showing a battery electrode plate group according to a second modified example.

A preferred embodiment of one aspect of the present invention will be described in detail below with reference to the attached drawings. In the following description, the same elements or elements having the same functions will be denoted by the same reference numerals, and duplicate descriptions will be omitted.

1 is a perspective view showing a part of the storage battery according to the present embodiment, with a part broken away. As shown in FIG. 1, the storage battery 1 is, for example, a lead storage battery. The storage battery 1 is used, for example, as a battery for an automobile, a backup power source used during a power outage, and a main power source for an electric vehicle (or electric vehicle) such as an electric forklift. In these cases, a battery pack consisting 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 storage battery having a clad electrode. The storage battery 1 includes a plate group 3, a positive terminal 5A, a negative terminal 5B, a water supply tap 6, and a case 7. The case 7 includes a main body 8 and a lid 9. The main body 8 is a box-shaped battery case. The main body 8 is formed of a material such as polypropylene. The main body 8 contains the plate group 3 and the electrolyte L (see FIG. 2 described later). 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 terminal 5A, a negative terminal 5B, and a refill tap 6. The refill tap 6 is provided between the positive terminal 5A and the negative terminal 5B.

2 is a cross-sectional view of a portion of the plate group. As shown in FIGS. 1 and 2, the plate group 3 has a plurality of positive electrodes 10, a plurality of negative electrodes 12, and a plurality of separators 13. In the plate group 3, the positive electrodes 10 and the negative electrodes 12 are arranged alternately. A separator 13 is located between adjacent positive electrodes 10 and negative electrodes 12. Therefore, the positive electrodes 10 are stacked on the negative electrodes 12 via the separators 13. In this embodiment, the negative electrodes 12 are arranged at the ends of the electrode group 3 in the arrangement direction of the positive electrodes 10, the negative electrodes 12, and the separators 13 (hereinafter, sometimes simply referred to as the "arrangement direction" or the "stacking direction"). In addition, each of the positive electrodes 10, the negative electrodes 12, and the separators 13 is also referred to as a battery plate group. When the electrode plate group 3 and the electrolyte L are housed in the main body 8, the electrolyte L is present in the gap between the positive electrode 10 and the separator 13, inside the separator 13, etc.

In the following, the arrangement direction and the stacking direction are referred to as the first direction X. The direction perpendicular to the first direction X is referred to as the second direction Y, and the direction perpendicular to the first direction X and the second direction Y is referred to as the third direction Z. In this embodiment, the second direction Y corresponds to the direction in which the electrode plate group 3 is housed in the case 7. The second direction Y and the third direction Z are perpendicular to each other, but are not limited to this. It is sufficient that the second direction Y and the third direction Z intersect each other.

3(a) is a diagram showing a positive electrode viewed from a first direction, and FIG. 3(b) is a diagram showing a part of the positive electrode viewed from the first direction. As shown in FIGS. 1, 2 and 3(a), the positive electrode 10 (first plate) is 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 has a current collector 14, a plurality of cylindrical bodies 15 that accommodate a part of the current collector 14, a positive electrode material 16 accommodated in the cylindrical bodies 15, and an upper seat 20 and a lower seat 25 that are attached to the current collector 14.

As shown in FIG. 3(b), the current collector 14 (first current collector) has a plurality of cores 14a, a connecting portion 14b connecting the plurality of cores 14a, and an ear portion 14c (first ear portion) protruding from the connecting portion 14b. The current collector 14 is formed, for example, by casting (pressure casting). The constituent material of the current collector 14 may be any conductive material, and examples of such materials include lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenic alloys. The lead alloy may contain selenium, silver, bismuth, etc.

The multiple core metals 14a are rod-shaped portions extending along the second direction Y and are arranged in a row along the third direction Z. One end of each core metal 14a in the second direction Y is connected to the connecting portion 14b. The other end of each core metal 14a in the second direction Y is fixed to the lower link seat 25. The length of each core metal 14a along the second direction Y is, for example, 170 to 600 mm. The connecting portion 14b is a portion that supports the core metal 14a and the ear portion 14c and extends along the third direction Z. When the positive electrode 10 is housed in the case 7, the connecting portion 14b is disposed on the positive electrode terminal 5A side in the second direction Y. In this embodiment, the multiple core metals 14a and the connecting portion 14b correspond to the main body portion 14d (first main body portion) of the current collector 14. In this case, the outer edge 14e located at one end of the main body portion 14d in the second direction Y is constituted by the connecting portion 14b. The ear 14c is a terminal portion that protrudes from the outer edge 14e of the main body 14d in the second direction Y and is connected to the positive electrode strap 17. In the second direction Y, the protruding direction of the ear 14c is opposite to the protruding direction of the core metal 14a. Therefore, the core metal 14a and the ear 14c do not overlap with each other in the first direction X. When the positive electrode 10 is housed in the case 7, the ear 14c and the outer edge 14e are located on the lid 9 side in the second direction Y.

The multiple cylindrical bodies 15 constitute a group of tubes (clad tubes) for holding active material. The group of tubes for holding active material is an assembly of cylindrical porous tubes also known as "gauntlets." Each cylindrical body 15 extends along the second direction Y and houses a corresponding core 14a. For example, one core 14a (first core) of the multiple cores 14a is inserted into one cylindrical body 15 (first cylindrical body) of the multiple cylindrical bodies 15, and another core 14a (second core) of the multiple cores 14a is inserted into another cylindrical body 15 (second cylindrical body) of the multiple cylindrical bodies 15.

The positive electrode material 16 is filled inside the cylindrical body 15 together with the metal core 14a. As shown in FIG. 2, the positive electrode material 16 surrounds the metal core 14a inside the cylindrical body 15. The positive electrode material 16 includes an active material. The active material includes both the active material after chemical conversion and the raw material of the active material before chemical conversion. The positive electrode material 16 includes the active material after chemical conversion. The positive electrode material 16 after chemical conversion includes, for example, the raw material of the positive electrode active material. In this embodiment, the positive electrode material 16 may include a positive electrode active material and an additive. The positive electrode active material is, for example, lead powder, red lead, or the like. Examples of the additive include a carbon material or short reinforcing fibers. The positive electrode active material after chemical conversion is, for example, lead dioxide, or the like.

Figure 4(a) is a schematic diagram showing the positive electrode as viewed from the second direction, and Figure 4(b) is a schematic diagram showing a part of the positive electrode as viewed from the third direction. As shown in Figures 3(a), (b) and 4(a), the upper connecting seat 20 is an insulating structure attached to the connecting portion 14b of the current collector 14, and covers the current collector 14 (the outer edge 14e of the main body portion 14d) as viewed from the second direction Y. The upper connecting seat 20 seals one end of each cylindrical body 15 in the second direction Y. For example, the upper connecting seat 20 is welded to each cylindrical body 15, but is not limited to this. The upper connecting seat 20 and each cylindrical body 15 may be fixed to each other, for example, via an adhesive or the like.

The upper linking seat 20 is provided, for example, by welding an insulating resin member to the current collector 14. One example of a method for forming the upper linking seat 20 is as follows. First, the connecting portion 14b is sandwiched between a pair of resin plates along the first direction X. At this time, the connecting portion 14b is positioned below the core metal 14a. Next, while sandwiching the connecting portion 14b and the pair of resin plates along the first direction X, the resin plates are heated. This melts each resin plate. The molten resin flows over the outer edge 14e of the current collector 14 and is integrated to cover the outer edge 14e. The molten resin is then cooled to form the upper linking seat 20.

The upper link 20 has a main portion 21 and a protruding portion 22. The main portion 21 is a portion that covers the connecting portion 14b, and covers the outer edge 14e when viewed from the second direction Y. When viewed from the second direction Y, at least the ear portion 14c of the current collector 14 is exposed from the main portion 21. As shown in FIG. 4(a), an opening 21a is provided in the main portion 21. The opening 21a is a portion that exposes a part of the current collector 14 when viewed from the second direction Y. Therefore, in this embodiment, a part of the outer edge 14e of the current collector 14 is exposed from the main portion 21 through the opening 21a. This part corresponds to the part of the outer edge 14e that was not covered by the flowed resin. The opening 21a overlaps the negative electrode 12 and the separator 13 in the first direction X. When viewed from the second direction Y, the opening 21a is located, for example, on the opposite side of the ear portion 14c through the center C of the positive electrode 10. The main portion 21 may have multiple openings 21a or may not have any openings 21a. When the main portion 21 has multiple openings 21a, all of the openings 21a may be located on the opposite side of the ear portion 14c through the center C of the positive electrode 10.

The protruding portion 22 is a portion that protrudes from the main portion 21 in the second direction Y and is integrated with the main portion 21. The protruding portion 22 is provided so as to be swingable along the first direction X, for example, with its base as a fulcrum. The protruding portion 22 is formed by a part of the resin that has flowed on the outer edge 14e. For example, the resin is cooled in a state where it hangs down due to the influence of gravity, thereby forming the protruding portion 22. When viewed from the second direction Y, the protruding portion 22 is located, for example, on the opposite side of the ear portion 14c across the center of the positive electrode 10 in the first direction X. A part of the protruding portion 22 may be located at or near the center of the positive electrode 10 in the first direction X. The tip 22a of the protruding portion 22 in the second direction Y is located closer to the cylindrical body 15 than the tip of the ear portion 14c. From the viewpoint of suppressing the accumulation of active material on the protruding portion 22, the tip 22a of the protruding portion 22 has, for example, an uneven shape. That is, the tip 22a of the protrusion 22 along the first direction X and/or the third direction Z changes irregularly. The thickness T2 of the protrusion 22 along the first direction X is smaller than the thickness T1 of the main portion 21 along the first direction X. For example, the thickness T2 is 0.6 to 0.7 mm. In this case, the protrusion 22 can oscillate well in accordance with the flow of the electrolyte L, etc.

As shown in FIG. 4(b), the upper connecting seat 20 has an opening 21b that communicates with the gap S located between the protrusion 22 and the current collector 14 when viewed from the third direction Z. The opening 21b functions as a hole for releasing gas and the like that is retained in the gap S. The opening 21b is formed when the resin flows.

Returning to FIG. 3(a), the lower linking seat 25 is an insulating structure that is attached to the multiple core metals 14a of the current collector 14. The lower linking seat 25 is attached to the current collector 14, for example, by inserting and fitting the core metal 14a of the current collector 14 into an insulating resin member. The lower linking seat 25 seals the other end of each cylindrical body 15 in the second direction Y. As a result, the position of each cylindrical body 15 in the positive electrode 10 is fixed by the upper linking seat 20 and the lower linking seat 25. For example, the lower linking seat 25 is welded to each cylindrical body 15, but is not limited to this. The lower linking seat 25 and each cylindrical body 15 may be fixed to each other, for example, by an adhesive or the like.

5 is a plan view showing a negative electrode according to the embodiment. As shown in FIG. 5, the negative electrode 12 (second electrode plate) is a 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 (second current collector) and a negative electrode material 12b. The current collector 12a is formed, for example, by casting, and has a negative electrode grid 12c and an ear portion 12d (second ear portion). The negative electrode grid 12c is a main body portion (second main body portion) of the negative electrode 12 and holds the negative electrode material 12b. In this embodiment, the thickness of the portion where the negative electrode material 12b is held in the negative electrode 12 is greater than the thickness of the negative electrode grid 12c, but is not limited to this. The negative electrode material 12b may contain 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 materials, lignin, and short reinforcing fibers. The ears 12d are terminals that protrude from the negative electrode grid 12c along the second direction Y and are connected to the negative electrode strap 18. The ears 12d and the negative electrode grid 12c do not overlap with each other in the first direction X. In this embodiment, the negative electrode grid 12c is covered by the separator 13. The negative electrode grid 12c is provided with protruding portions 12e and 12f. The protruding portions 12e and 12f are arranged at a predetermined interval and are legs that protrude outward from the negative electrode grid 12c. The protruding portions 12e and 12f protrude along a direction opposite to the protruding direction of the ears 12d. In this embodiment, the protruding direction of the ears 12d and the protruding directions of the protruding portions 12e and 12f are each perpendicular to the arrangement direction. Additionally, the ears 12d and the negative electrode grid 12c do not overlap with each other in the arrangement direction.

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 electrically insulates the positive electrode 10 and the negative electrode 12 while allowing ions to pass therethrough and is resistant to oxidation on the positive electrode 10 side and reduction on the negative electrode 12 side. Examples of materials for the separator 13 include glass fiber, resin, and inorganic substances. In this embodiment, the separator 13 covers the negative electrode grid 12c and the protrusions 12e and 12f of the negative electrode 12, and the ears 12d of the negative electrode 12 are exposed from the separator 13.

Now, with reference to Figures 6(a) and (b), the structure of the separator sheet, which is the pre-processed product of the separator 13, will be described. Figure 6(a) is a plan view showing the separator sheet, and Figure 6(b) is a schematic cross-sectional view taken along line VIb-VIb in Figure 6(a). As shown in Figures 6(a) and (b), the separator sheet 30 has a base 31, a pair of edges 32, 33, and a number of ribs 34.

The base 31 is a sheet-like portion that is the main portion of the separator sheet 30 and is flexible. The base 31 has a first main surface 31a and a second main surface 31b that is located on the opposite side of the first main surface 31a in the first direction X. In this embodiment, the first main surface 31a and the second main surface 31b have a rectangular shape when viewed from the first direction X, but are not limited to this.

The pair of edges 32, 33 are provided at both ends of the separator sheet 30 in the third direction Z. Each of the edges 32, 33 extends from one end of the separator sheet 30 in the second direction Y (e.g., the upper end side of the paper in FIG. 6(a)) to the other end (e.g., the lower end side of the paper in FIG. 6(a)). Each of the edges 32, 33 may extend continuously or intermittently. The edge 32 is provided at one end of the separator sheet 30 in the third direction Z (e.g., the left end side of the paper in FIG. 6(a)), and the edge 33 is provided at the other end of the separator sheet 30 in the third direction Z (e.g., the right end side of the paper in FIG. 6(a)). In this embodiment, the pair of edges 32, 33 are provided with ribs different from the rib 34. For example, each of the pair of edges 32, 33 may have one or more ribs or the like extending from one end to the other end of the separator sheet 30 in the second direction Y.

The multiple ribs 34 are provided, for example, to improve the durability of the separator sheet 30 and the fluidity of the electrolyte in the case 7. The multiple ribs 34 protrude from the base 31 along the first direction X and are spaced apart from each other. Each of the multiple ribs 34 has a rectangular shape when viewed from the first direction X. Each of the multiple ribs 34 extends from one end to the other end of the separator sheet 30 in the second direction Y and extends parallel to each other. The 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 trapezoid or an inverted trapezoid. The dimension (width) of the rib 34 along the third direction Z is, for example, 0.30% to 2.5% of the dimension of the separator sheet 30 along the third direction Z. The dimension (height) of the rib 34 along the first direction X is, for example, greater than 100% and less than or equal to 1000% of the dimension (thickness) of the base 31 along the first direction X.

As shown in FIG. 6(b), the rib 34 has a plurality of first ribs 34a provided on the first main surface 31a and a plurality of second ribs 34b provided on the second main surface 31b. The first ribs 34a protrude from the first main surface 31a along the first direction X. The second ribs 34b protrude from the second main surface 31b on the side opposite the first ribs 34a. In this embodiment, the first ribs 34a and the second ribs 34b have the same shape and completely overlap each other.

Next, referring to FIG. 7, the structure of the negative electrode 12 and the separator 13 included in the electrode plate group 3 will be described in detail. FIG. 7 is a plan view showing the negative electrode wrapped in the separator. As shown in FIG. 7, the separator 13 corresponds to a pouch-shaped processed product of the separator sheet and wraps the negative electrode 12. As described above, the ear portion 12d of the negative electrode 12 is exposed from the separator 13, and the convex portions 12e and 12f of the negative electrode 12 are covered by the separator 13. The separator 13 is formed, for example, by folding one separator sheet 30 in half along the second direction Y and then sealing the desired portions. At this time, the separator sheet 30 is folded back on the convex portions 12e and 12f side of the negative electrode 12 in the second direction Y so that the negative electrode 12 is sandwiched between the separator sheet 30. At least a part of each of the edge portions 32 and 33 is located outside the negative electrode 12 in the third direction Z. From the viewpoint of improving workability, the separator sheet 30 may be folded in half as the negative electrode 12 moves. The separator 13 has a main portion 41, a pair of seal portions 42, 43, a bent portion 44, and a joint portion 45.

The main portion 41 is a portion that houses the negative electrode grid 12c of the negative electrode 12. The main portion 41 is composed of the base portion 31 and edge portions 32, 33 (see FIG. 6(a)) of the separator sheet 30. Therefore, the main portion 41 has a first main surface 31a on which the first rib 34a is provided, and a second main surface 31b on which the second rib 34b is provided (see FIG. 6(b)). In this embodiment, the first main surface 31a faces the negative electrode 12, and the second main surface 31b is an exposed surface. Therefore, the positive electrode 10 (see FIG. 1) in the electrode plate group 3 faces the second main surface 31b of the separator sheet 30.

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. 6A), and the seal portion 43 is formed on the edge portion 33 (see FIG. 6A). Each of the seal portions 42, 43 is located outside the negative electrode 12 in the third direction Z. Each of the seal portions 42, 43 extends in the second direction Y. This allows the movement of the negative electrode 12 along the third direction Z to be suppressed by the seal portions 42, 43. 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 be provided with an area through which the electrolyte can pass. The seal portions 42, 43 are, for example, ultrasonic welding portions, heat seal portions, cold seal portions, gear seal portions, etc. The gear seal portion is a portion that is mechanically bonded by pressure using a gear. In this embodiment, each of the seal portions 42 and 43 is a gear seal portion that extends from one end of the separator 13 to the other end in the second direction Y.

The bent portion 44 is a portion that is folded back in the separator sheet 30. At least a portion of the bent portion 44 can abut against 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 in the separator 13. The opening 44a is provided in a position that does not overlap either of the protrusions 12e and 12f in the second direction Y. The opening 44a is provided, for example, in the center of the separator 13 in the third 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 joint 45 is a portion for maintaining the state of the separator sheet 30 folded in two, similar to the seal portions 42 and 43. The joint 45 is a portion for joining a part of the first main surface 31a of the separator sheet 30 to another part. The part and the other part are portions that do not overlap the negative electrode 12 in the first direction X, and are located on the opposite side of the bent portion 44 in the second direction Y. Therefore, the joint 45 is located on one end side of the separator 13 in the second direction Y, and is located outside the negative electrode 12 as viewed from the first direction X. The joint 45 faces the negative electrode grid 12c of the negative electrode 12 in the second direction Y, and faces the ear portion 12d in the third direction Z. In the storage battery 1, at least the joint 45 is located closer to the lid 9 than the negative electrode 12 in the second direction Y. The joint 45 also extends along the third direction Z. Specifically, the joint portion 45 extends from one end of the separator 13 in the third direction Z to the other end, and is provided in the main portion 41 and the seal portion 42. That is, a portion of the joint portion 45 overlaps with the seal portion 42.

In this embodiment, the joint 45 is, for example, a portion where the separator sheet 30 itself is welded. At the joint 45, a part of the first main surface 31a and another part are welded together without any gaps. Therefore, when viewed from the second direction Y, a part of the negative electrode 12 is covered by the part of the separator 13 where the joint 45 is formed. From the viewpoint of preventing welding defects, the joint 45 may be formed by ultrasonic welding or the like. The joint 45 may be provided after the seal portions 42, 43 are formed, or may be provided before the seal portions 42, 43 are formed.

In the third direction Z, the joint 45 and the ear 12d are spaced apart from each other. Therefore, an unjoined portion of the separator sheet 30 exists between the joint 45 and the ear 12d in the third direction Z. The presence of the unjoined portion and the opening 44a of the bent portion 44 can prevent gas from accumulating in the separator 13. In addition, the fluidity of the electrolyte L in the electrode plate group 3 can also be improved.

Figure 8 is an enlarged view of the main parts of the electrode plate group and each strap. As shown in Figure 8, the joint 45 of the separator 13 is located closer to the positive electrode strap 17 in the second direction Y than the upper connecting seat 20 of the positive electrode 10. The joint 45 also overlaps with the ear 14c of the positive electrode 10 in the first direction X. When viewed from the first direction X, the ear 14c is located between one end and the other end of the joint 45 in the third direction Z. From the viewpoint of preventing a short circuit between the positive electrode strap 17 and the negative electrode 12, the joint 45 may be located below the positive electrode strap 17 in the second direction Y.

Next, an example of a manufacturing method of the storage battery 1 in this embodiment will be briefly described. First, the separator sheet 30 and the negative electrode 12 are prepared. At this time, the first main surface 31a of the separator sheet 30 and the negative electrode 12 are opposed to each other. Next, the separator sheet 30 is folded in half to form a bent portion 44 and sandwich the negative electrode 12 between the separator sheet 30. At this time, the negative electrode grid 12c of the negative electrode 12 is completely covered by the separator sheet 30, and a part of the ear portion 12d of the negative electrode 12 is exposed from the separator sheet 30. Next, the seal portions 42, 43 and the joint portion 45 are formed on the separator sheet 30. The seal portions 42, 43 are formed, for example, by a gear seal or the like. The joint portion 45 is formed, for example, by ultrasonic welding using an ultrasonic welding device including a horn. Next, an opening 44a is formed in the bent portion 44 to form the separator 13 that encases the negative electrode 12.

Next, a plurality of positive electrodes 10 and a plurality of negative electrodes 12 wrapped in separators 13 are prepared. Then, as shown in FIG. 9, the positive electrodes 10 and the negative electrodes 12 wrapped in separators 13 are stacked. At this time, the positive electrodes 10 and the negative electrodes 12 are stacked so that the ears 14c of the positive electrodes 10 overlap the joints 45 of the separators 13 and the ears 12d of the negative electrodes 12 overlap the upper link seat 20 in the first direction X, which corresponds to the direction in which the positive electrodes 10 and the negative electrodes 12 are stacked. In this embodiment, the opening 21a of the upper link seat 20 overlaps the portion of the negative electrodes 12 that is covered by the separators 13 in the first direction X. Also, no opening is provided in the portion of the upper link seat 20 that overlaps the ears 12d when viewed from the second direction Y.

Then, the ears 10a of the positive electrodes 10 are electrically connected to the positive electrode strap 17, and the ears 12d of the negative electrodes 12 are electrically connected to the negative electrode strap 18. This forms an electrode plate group 3 including a plurality of positive electrodes 10, a plurality of negative electrodes 12, and a plurality of separators 13. The electrode plate group 3 is then housed in the main body 8. The main body 8 is then sealed with the 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. Next, the electrolyte L is supplied into the case 7 via the water supply tap 6. This completes the manufacture of the storage battery 1.

The following describes the effects of the electrode plate group 3 included in the storage battery 1 manufactured by the manufacturing method according to this embodiment, while highlighting the problems that have existed in the past.

It is well known that when a lead-acid battery is charged, a water electrolysis reaction occurs as a side reaction. This side reaction generates oxygen gas from the positive electrode and hydrogen gas from the negative electrode. This gas generation can cause the positive electrode active material to be detached from the positive electrode, and the negative electrode active material to be detached from the negative electrode. The detached active material diffuses into the electrolyte due to the flow of each gas, and then settles. At this time, the active material accumulates, for example, on the bottom of the case, on the separator, and on the upper connecting seat. In addition, the positive electrode active material tends to aggregate on the negative electrode lugs, negative electrode straps, etc., and the negative electrode active material tends to aggregate on the positive electrode lugs, positive electrode straps, etc. The aggregated active materials may further aggregate and reach the adjacent positive or negative electrodes. In this case, a short circuit occurs between the positive and negative electrodes with the aggregated active material as a conductive path.

In contrast, in the electrode plate group 3 according to this embodiment, the ear 12d of the current collector 12a included in the negative electrode 12 overlaps with the upper link 20 that covers at least a part of the outer edge 14e of the positive electrode 10 in the first direction X. As a result, the upper link 20 is provided on the shortest path along the first direction X between the ear 12d and the positive electrode 10 as viewed from the second direction Y. For this reason, for example, when the electrode plate group 3 is housed in the case 7 together with the electrolyte L, and the positive electrode active material and/or the negative electrode active material accumulates on the ear 12d, the short circuit between the positive electrode 10 and the ear 12d via the shortest path is inhibited by the upper link 20. In addition, as viewed from the second direction Y, a part of the negative electrode 12 is covered and hidden by the separator 13. As a result, the short circuit between the positive electrode 10 and the negative electrode 12 via the part of the negative electrode 12 is also inhibited by the separator 13. In addition, another part of the negative electrode 12 is not covered by the separator 13, so the flow, diffusion, etc. of the electrolyte L between the negative electrode 12 and the separator 13 is not easily hindered by the separator 13. Therefore, by using the electrode plate group 3 according to this embodiment, it is possible to provide a storage battery 1 that can suppress short circuits caused by the accumulation of active material while maintaining the diffusibility of the electrolyte L.

In this embodiment, the upper connecting seat 20 has an opening 21a that exposes a portion of the current collector 14 when viewed from the second direction Y. This prevents the electrolyte L and the like from accumulating between the current collector 14 and the upper connecting seat 20.

In this embodiment, the opening 21a overlaps with a part of the negative electrode 12 that is covered by the separator 13 in the first direction X. Therefore, when viewed from the second direction Y, the separator 13 is provided on the shortest path along the first direction X between the opening 21a and the negative electrode 12. Therefore, even if active material accumulates in the opening 21a, a short circuit between the positive electrode 10 and the negative electrode 12 using the active material as a conductive path is easily inhibited by the separator 13.

In this embodiment, the opening 21a is located on the opposite side of the ear portion 14c across the center C of the positive electrode 10 when viewed from the second direction Y.

In this embodiment, the upper link 20, which is an insulating structure, has a main portion 21 that covers at least a portion of the outer edge 14e when viewed from the second direction Y, and a protruding portion 22 that protrudes from the main portion 21 in the second direction Y, and the thickness T2 of the protruding portion 22 along the first direction X is smaller than the thickness T1 of the main portion 21 along the first direction X. For this reason, for example, when the protruding portion 22 oscillates due to the flow of the electrolyte L, etc., the active material is less likely to accumulate on the main portion 21.

In this embodiment, the tip 22a of the protrusion 22 has an uneven shape. This makes it difficult for active material to accumulate on the tip 22a of the protrusion 22.

In this embodiment, the current collector 14 has multiple cores 14a and a connecting portion 14b that connects the cores 14a and includes an outer edge 14e, and the positive electrode 10 has multiple cylindrical bodies 15 into which the multiple cores 14a are respectively inserted, and a positive electrode material 16 that is filled into each cylindrical body 15. Therefore, the detachment of the positive electrode material 16 from the cores 14a is suppressed by the cylindrical bodies 15.

In this embodiment, the upper connecting seat 20 seals one end of each cylindrical body 15. This makes it difficult for the positive electrode material 16 to flow out of each cylindrical body 15. In addition, the lower connecting seat 25 seals the other end of each cylindrical body 15. This makes it even difficult for the positive electrode material 16 to flow out of each cylindrical body 15.

In this embodiment, the storage battery 1 is a lead-acid battery. Therefore, even if hydrogen gas is generated from the negative electrode 12, the hydrogen gas is unlikely to accumulate.

In the above embodiment, 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 plate group, the separator sheet may be folded in half along the third direction. In this case, an opening does not need to be provided at the bent portion of the separator.

In the above embodiment, the separator is formed from one separator sheet, but this is not limited thereto. For example, the separator may be formed from multiple separator sheets. In this case, seal portions may be formed on both ends of the separator in the third direction, or seal portions may be formed only on one side in the third direction. In addition, it is preferable that joint portions are formed on both sides of the separator in the second direction, but this is not limited thereto. Joint portions may be formed only on one side in the second direction. Therefore, when the separator is formed from multiple separator sheets, the separator may be a bag-shaped processed product, a cylindrical processed product, or a processed product different from the bag-shaped processed product and the cylindrical processed product.

Below, a modified example of the above embodiment will be described with reference to Figures 10 and 11. In the following modified example, explanations of points that overlap with the above embodiment will be omitted. Therefore, below, differences from the above embodiment will be mainly described.

Figure 10 is a plan view showing a negative electrode wrapped in a separator according to the first modified example. As shown in Figure 10, the separator 13A does not have a bent portion that faces the protrusions 12e and 12f of the negative electrode 12 in the second direction Y, unlike the above embodiment. Therefore, in the first modified example, the separator 13A is composed of two separator sheets 30. For example, the separator sheet 30 (hereinafter sometimes referred to as the "first separator sheet") located at one end of the negative electrode 12 in the first direction X and the separator sheet 30 (hereinafter sometimes referred to as the "second separator sheet") located at the other end of the negative electrode 12 in the first direction X are joined to each other at the seal portions 42 and 43, etc., to form the separator 13A.

Instead of the bent portion, the separator 13A has, in addition to the joint 45, joints 51 and 52 that face the negative electrode 12 in the second direction Y. Each of the joints 51 and 52 is a portion where a part of the separator 13A and another part are joined to each other. A part of the separator 13A is included in the first separator sheet, and the other part of the separator 13A is included in the second separator sheet. The joint 51 faces the convex portion 12e in the second direction Y, and the joint 52 faces the convex portion 12f in the second direction Y. Each of the joints 51 and 52 extends along the third direction Z. The joint 51 extends from one end of the separator 13A to the other end in the third direction Z, similar to the joint 45, and is provided in the main portion 41 and the seal portion 42. The joint portion 52 extends from the other end toward one end in the third direction Z and is provided in the main portion 41 and the seal portion 42. The joint portions 51, 52 are aligned in the third direction Z and are spaced apart from each other. An opening 53 is provided between the joint portions 51, 52 in the third direction Z. The opening 53 is a portion of the separator 13A where the first separator sheet and the second separator sheet are not joined to each other, and is located on the side of the protruding portions 12e, 12f in the second direction Y. The opening 53 does not overlap the protruding portions 12e, 12f in the second direction Y.

From the viewpoint of strengthening the bonding between the separator sheets by the bonding portions 51, 52, each of the bonding portions 51, 52 is, for example, a portion where the first separator sheet and the second separator sheet are welded to each other. From the viewpoint of preventing poor welding, each of the bonding portions 51, 52 may be formed by ultrasonic welding or the like. Each of the bonding portions 51, 52 may be provided after the formation of the seal portions 42, 43, or may be provided before the formation of the seal portions 42, 43.

The first modified example described above can also achieve the same effects as the above embodiment. In the first modified example, the separator 13B is composed of two separator sheets 30, but is not limited to this. For example, a separator sheet folded in half along the third direction Z may be used. In other words, the separator according to the first modified example may be formed from a single separator sheet. In this case, a seal portion is formed only on one end of the separator in the third direction Z.

Figure 11 is a schematic plan view showing a battery plate group according to the second modified example. As shown in Figure 11, in the second modified example, a separator 13B formed from a single separator sheet is used in the plate group 3A. Specifically, the separator 13B included in the plate group 3A according to the second modified example has a sheet shape folded like an accordion when viewed from the second direction Y. In other words, the separator 13B is arranged so as to meander between the positive electrode 10 and the negative electrode 12 when viewed from the second direction. Although not shown in Figure 11, ribs may be formed on the surface of the separator 13B as in the above embodiment.

The separator 13B has a plurality of first portions 61, a plurality of second portions 62, and a plurality of third portions 63. Each of the plurality of first portions 61 overlaps the positive electrode 10 and the negative electrode 12 in the first direction X. A portion of the plurality of first portions 61 functions to prevent short-circuiting between adjacent positive electrodes 10 and negative electrodes 12. Another portion of the plurality of first portions 61 is located at an end of the electrode plate group 3 in the first direction X. The other portion functions to suppress contact between the positive electrode 10 and the negative electrode 12 and the case 7.

Each of the second parts 62 is a connection part that connects adjacent first parts 61 in the first direction X, and is located at one end of the electrode plate group 3 in the third direction Z. Each second part 62 faces the side of the corresponding negative electrode 12 in the third direction Z. Each of the third parts 63 is a connection part that connects adjacent first parts 61 in the first direction X, and is located at the other end of the electrode plate group 3 in the third direction Z. Each third part 63 has a main connection part 63a that functions as the above-mentioned connection part, and an outer edge connection part 63b that is provided by the presence of the joint part 45A in the separator 13B. The main connection part 63a faces the side of the corresponding negative electrode 12 in the third direction Z. The outer edge connection part 63b overlaps with the negative electrode 12 along the third direction Z when viewed from the second direction Y, and is located above the positive electrode 10 and the negative electrode 12 in the second direction Y. The second portion 62 and the main connection portion 63a of the third portion 63 do not overlap each other in the third direction Z. In the second modified example, each second portion 62 contacts one end of the negative electrode 12 in the third direction Z, and each third portion 63 contacts one end of the positive electrode 10 in the third direction Z.

When viewed from the first direction X, a portion of the separator 13B is located outside the positive electrode 10 and the negative electrode 12 in the second direction Y. In addition, a portion of the first portion 61 adjacent to each other in the first direction X is joined at a joint 45A provided at one end in the second direction Y. The joint 45A overlaps the negative electrode 12 in the second direction Y and extends from one end of the electrode plate group 3 to the other end in the third direction Z. Therefore, when viewed from the second direction Y, a portion of the negative electrode 12 is covered by the region in which the joint 45A is provided in the separator 13B and the surrounding region. From the viewpoint of preventing a short circuit between the positive electrode 10 and the negative electrode 12, it is preferable that the portion of the negative electrode 12 covered by the separator 13B overlaps with the opening 21a provided in the upper connecting seat 20 of the positive electrode 10 in the first direction X when viewed from the second direction. Although not shown, another joint may be formed on the opposite side of the joint 45A between the positive electrode 10 and the negative electrode 12 in the second direction Y. In this case, it is possible to effectively prevent misalignment between the separator 13B and the positive electrode 10 in the second direction Y, and between the separator 13B and the negative electrode 12 in the second direction Y.

The second modified example described above can also achieve the same effects as the above embodiment. In the second modified example, the separator 13B is composed of a single separator sheet, but this is not limited thereto. For example, the separator 13B may be composed of multiple sheets integrated together. Also, the joint 45A is provided on each negative electrode 12, but this is not limited thereto. The joint 45A may be provided on some of the multiple negative electrodes 12.

The battery plate group according to one aspect of the present invention 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, the first modification and the second modification may be combined.

In the above embodiment and the above modified example, the rib extends in a straight line when viewed from the first direction, but is not limited to this. For example, the rib may extend in a wavy line or a zigzag line when viewed from the first direction. Also, the rib may be dot-shaped, circular, elliptical, or polygonal when viewed from the first direction. Alternatively, the rib may be polygonal pyramid-shaped, polygonal truncated pyramid-shaped, conical, or conical truncated. The cross section of the rib may be semicircular or polygonal. The rib may extend along the second direction or along the third direction. A fishbone structure may be formed by multiple ribs when viewed from the first direction. In the above embodiment and the above modified example, the rib is provided on the first main surface and the second main surface, but is not limited to this. The rib may be provided on only one of the first main surface and the second main surface. For example, the rib may be provided only on the second main surface.

DESCRIPTION OF SYMBOLS 1... Storage battery, 3, 3A... Electrode plate group, 5A... Positive electrode terminal, 5B... Negative electrode terminal, 7... Case, 8... Main body, 9... Lid, 10... Positive electrode (first electrode plate), 12... Negative electrode (second electrode plate), 12a... Current collector (second current collector), 12b... Negative electrode material, 12c... Negative electrode grid body, 1 2d... Ear part (second ear part), 12e, 12f... Convex part, 13, 13A, 13B... Separator, 14... Current collector (first current collector), 14a... Core metal, 14b... Connection part, 14c... Ear part (first ear part), 14d... Main body part, 14e... Outer edge, 15... Cylindrical body, 16...cathode material, 20...upper link (insulating structure), 21...main part, 21a, 21b...opening, 22...projection, 22a...tip, 25...lower link, 30...separator sheet, 31...base, 31a...first main surface, 31b...second main surface, 32, 33...edge, 34...rib, 34a...first rib, 34b...second rib, 41...main part, 42, 43...seal part, 44...bent part, 44a...opening, 45, 45A...joint, 61...first part, 62...second part, 63...third part, C...center, L...electrolyte.

Claims (12)

a first electrode plate and a second electrode plate stacked on top of each other in a first direction;
a separator located between the first plate and the second plate;
Equipped with
The first electrode plate has a first main body portion, a first current collector including a first ear portion protruding from an outer edge of the first main body portion in a second direction perpendicular to the first direction, and an insulating structure covering at least a portion of the outer edge when viewed from the second direction,
the second electrode plate has a second current collector including a second body portion and a second ear portion protruding from the second body portion in the second direction;
At least a portion of the second ear overlaps the insulating structure in the first direction;
When viewed from the second direction, a portion of the second plate is covered by the separator ,
the insulating structure has an opening exposing a portion of the first current collector when viewed from the second direction;
Electrode plate group for batteries. The battery plate group according to claim 1 , wherein the opening overlaps the portion of the second plate that is obscured by the separator in the first direction. The battery plate group according to claim 2 , wherein the opening is located on an opposite side of the first lug portion across a center of the first plate when viewed from the second direction. the insulating structure has a main portion covering at least a part of the outer edge when viewed from the second direction, and a protruding portion protruding from the main portion in the second direction,
4. The battery plate group according to claim 1 , wherein a thickness of the protruding portion along the first direction is smaller than a thickness of the main portion along the first direction. The battery electrode assembly according to claim 4 , wherein a tip of the protrusion has an uneven shape. the first body portion has a first core bar, a second core bar, and a connecting portion that connects the first core bar and the second core bar and includes the outer edge,
The battery plate group according to any one of claims 1 to 5, wherein the first electrode plate further comprises a first cylindrical body into which the first core is inserted, a second cylindrical body into which the second core is inserted, and a positive electrode active material filled into each of the first cylindrical body and the second cylindrical body. The battery plate group according to claim 6 , wherein the insulating structure seals one end of the first cylindrical body and one end of the second cylindrical body. A battery electrode group according to any one of claims 1 to 7 ;
a battery case in which the battery plate group is housed;
A storage battery comprising: 9. The battery of claim 8 which is a lead acid battery. A battery pack comprising the storage battery according to claim 8 or 9 . An electric vehicle comprising the battery pack according to claim 10 . A method for producing a battery electrode assembly according to any one of claims 1 to 7 , comprising the steps of:
A method for manufacturing a battery plate group, comprising a step of stacking the first plate and the second plate so that the second ear portion overlaps the insulating structure in the first direction.

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