Battery cell

Abstract

A battery cell comprises a capacitor and an electrode plate. The capacitor comprises an electrode laminate in which a plurality of positive electrode current collectors and a plurality of negative electrode current collectors are laminated, and a current collector portion that is formed by binding the positive electrode current collectors or the negative electrode current collectors, and which protrudes from the side of the electrode laminate. The current collector portion has a first bend portion and a specific portion that is connected to the electrode laminate through the first bend portion and extends along the stacking direction of the electrode laminate. The electrode plate comprises a first plate portion that is arranged along the specific portion and bonded to the specific portion, a second bend portion, and a second plate portion that is connected to the first plate portion through the second bend portion.

Description

Technology Field

[0001] The technology disclosed in this specification relates to battery cells. Background Technology

[0002] The capacitor of the battery cell disclosed in Japanese Patent Publication No. 2025-18622 has an electrode stack and a collecting portion. The electrode stack has a structure in which a plurality of positive electrode collecting foils and a plurality of negative electrode collecting foils are stacked. The collecting portion is a part that binds the positive electrode collecting foils or negative electrode collecting foils. The collecting portion protrudes from the side of the electrode stack. The electrode plate, also called a collecting plate, is bonded to the collecting portion. The electrode plate is a terminal that outputs the voltage of the battery cell.

[0003] In Japanese Patent Publication No. 2025-18622, a collecting portion is extended along a direction intersecting the stacking direction of the electrode stack (hereinafter referred to as the transverse direction). The electrode plate is extended further in the transverse direction (i.e., the direction extending the collecting portion) from the bonding position to the collecting portion. Because of this, in the structure of the battery cell of Japanese Patent Publication No. 2025-18622, the distance from the side of the electrode stack to the leading edge of the electrode plate is increased, and the battery cell becomes larger. This specification proposes a technology for miniaturizing the battery cell.

[0004] The battery cell disclosed in this specification is,

[0005] The entire axis and,

[0006] electrode plate

[0007] has

[0008] The entire shaft mentioned above,

[0009] An electrode laminate in which a plurality of positive electrode current collectors and a plurality of negative electrode current collectors are stacked, and

[0010] A collecting portion comprising the positive electrode collecting foil or the negative electrode collecting foil, wherein the collecting portion protrudes from the side of the electrode stack.

[0011] has

[0012] The above collection unit,

[0013] The first bend and,

[0014] A specific part that is connected to the electrode laminate through the first bend and extends along the stacking direction of the electrode laminate.

[0015] has

[0016] The above electrode plate is arranged along the specific portion and has a first plate portion bonded to the specific portion, and

[0017] The second bend and,

[0018] It has a second plate portion that is connected to the first plate portion through the second bend portion and extends from the second bend portion toward the electrode stack.

[0019] In this battery cell, the junction between the collecting portion and the electrode plate (i.e., the specific portion and the first plate portion) is extended along the stacking direction. The electrode plate is bent at the second bend, and the second plate portion extending from the second bend is extended in the transverse direction. In this structure, since the junction between the collecting portion and the electrode plate is extended along the stacking direction, the distance from the side of the electrode stack to the leading edge of the second plate portion (i.e., the dimension in the transverse direction) can be made shorter than in the conventional method. Therefore, according to the structure of this battery cell, the battery cell can be miniaturized. Brief explanation of the drawing

[0020] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which similar elements are indicated by similar reference numerals. FIG. 1 is a perspective view of a battery cell (10); FIG. 2 is a plan view of a battery cell (10) along the thickness direction; FIG. 3 is a cross-sectional view of a battery cell of an embodiment along the line III-III of FIG. 2; FIG. 4 is a cross-sectional view of a battery cell prior to the sealing of the outer body; FIG. 5 is a cross-sectional view of a battery cell of a comparative example corresponding to FIG. 3; FIG. 6 is an explanatory diagram of a method for manufacturing a battery cell of an embodiment; and FIG. 7 is a cross-sectional view of a battery cell of a modified example corresponding to FIG. 3. Specific details for implementing the invention

[0021] In one example battery cell disclosed in this specification, the collecting portion may be connected to the side of the electrode stack at a position offset from the center of the electrode stack in the stacking direction. The second plate portion may be disposed at the center of the electrode stack in the stacking direction.

[0022] According to this configuration, the second plate can be placed at the center of the electrode laminate in the stacking direction.

[0023] In one example battery cell disclosed in this specification, a film material surrounding the entire shaft may be further provided. The film material may be welded to the second plate portion.

[0024] As illustrated in FIG. 1, the battery cell (10) of the embodiment has a rectangular flat plate shape. Hereinafter, the thickness direction of the battery cell (10) is referred to as the z-direction, the long side direction of the battery cell (10) is referred to as the x-direction, and the direction orthogonal to the z-direction and the x-direction is referred to as the y-direction. When using the battery cell (10), a plurality of battery cells (10) are stacked in the z-direction to form a battery module. As illustrated in FIG. 2, the battery cell (10) has an outer body (30) and a capacitor (20) housed inside the outer body (30). Additionally, electrode plates (50, 60) are provided at both ends of the battery cell (10) in the x-direction. The electrode plate (50) is the positive electrode of the battery cell (10), and the electrode plate (60) is the negative electrode of the battery cell (10).

[0025] The capacitor (20) is a rechargeable battery element and outputs a DC voltage. As shown in FIG. 3, the capacitor (20) has an electrode stack (22) and a collecting part (24). The electrode stack (22) is a stack formed by alternately stacking a positive electrode collecting foil (23) and a negative electrode collecting foil (25) with a separator (27) interposed. The positive electrode collecting foil (23), the negative electrode collecting foil (25), and the separator (27) are stacked in the z-direction. The collecting part (24) is a portion formed by binding a plurality of positive electrode collecting foils (23). The collecting part (24) is provided on the side (22a) of the electrode stack (22). Additionally, although not shown, a collecting part formed by binding a plurality of negative electrode collecting foils (25) is provided on the side of the electrode stack (22) opposite the side (22a). The capacitor (20) is immersed in an electrolyte filled inside the outer body (30). The electrode plate (50) is connected to the positive electrode collecting part (24). The electrode plate (60) is connected to the negative electrode collecting part.

[0026] As illustrated in FIGS. 1 and 2, the outer body (30) has sides (30a to 30d). Sides (30a, 30c) are sides along the x-direction. Sides (30b, 30d) are sides along the y-direction. FIG. 4 is a cross-sectional view of a battery cell (10) before sealing the outer body (30). As illustrated in FIG. 4, the outer body (30) is composed of a thin film. The film constituting the outer body (30) is a laminate film having a resin coating film on both surfaces of an aluminum foil. The film constituting the outer body (30) is formed into a container shape having a bottom (34) and a cover (36) by embossing. A bend (39) is provided on the side (30a) of the outer body (30). The cover portion (36) can oscillate relative to the bottom portion (34) around the bend portion (39). The bottom portion (34) has a frame portion (34a) and a cup portion (34b). The cup portion (34b) has a cup shape with a concave portion on its upper surface. The frame portion (34a) is a planar portion provided around the cup portion (34b). As shown in FIG. 1, the frame portion (34a) is provided around the cup portion (34b), excluding the side (30a). As shown in FIG. 4, the shaft portion (20) is placed within the cup portion (34b). The cover portion (36) has a frame portion (36a) and a cap portion (36b). The cap portion (36b) has a cap shape with a concave portion on its lower surface. The frame portion (36a) is a planar portion provided around the cap portion (36b). As shown in FIG. 1, the frame portion (36a) is provided around the cap portion (36b), excluding the side (30a). When the cover portion (36) is closed, the upper part of the shaft (20) is covered by the cap portion (36b). Also, when the cover portion (36) is closed, as shown in FIG. 1, the frame portion (36a) is stacked on the frame portion (34a).

[0027] As illustrated in FIGS. 1 and 2, the electrode plates (50, 60) are extended from the shaft (20) to the outside of the outer body (30). The electrode plates (50, 60) are extended from the inside to the outside of the outer body (30) through the interface between the frame portion (36a) and the frame portion (34a). In FIG. 2, the dot-hatched area is the welded portion (70). The welded portion (70) is provided in the part where the frame portion (36a) and the frame portion (34a) overlap. The welded portion (70) is an area where the frame portion (34a) is connected to the frame portion (36a) by thermal welding. As illustrated in FIG. 2, the welded portion (70) is extended along the outer circumference of the frame portions (34a, 36a). The welded portion (70) extends linearly across the electrode plates (50, 60). In the region within the welded portion (70) where the electrode plates (50, 60) are not present, the frame portion (34a) is welded to the frame portion (36a). In the region within the welded portion (70) where the electrode plate (50) is present, the frame portion (34a) is welded to the lower surface of the electrode plate (50), and the frame portion (36a) is welded to the upper surface of the electrode plate (50). In the region within the welded portion (70) where the electrode plate (60) is present, the frame portion (34a) is welded to the lower surface of the electrode plate (60), and the frame portion (36a) is welded to the upper surface of the electrode plate (60). In the welded portion (70), the outer body (30) is sealed.

[0028] Next, the connection structure between the electrode plate and the capacitor (20) will be explained in detail. As described above, the electrode plate (50) is connected to the positive electrode collecting part (24), and the electrode plate (60) is connected to the negative electrode collecting part. The connection structure between the electrode plate (50) and the positive electrode collecting part (24) is approximately equivalent to the connection structure between the electrode plate (60) and the negative electrode collecting part. Therefore, the connection structure between the electrode plate (50) and the positive electrode collecting part (24) will be explained below.

[0029] As illustrated in FIG. 3, the collecting portion (24) protrudes from the side (22a) of the electrode stack (22). In FIG. 3, the center C1 is the center of the electrode stack (22) in the stacking direction. The collecting portion (24) is connected to the side (22a) of the electrode stack (22) at a position offset from the center C1. The collecting portion (24) has a curved portion (24a) and a plate-like portion (24b) located at the leading edge of the curved portion (24a). The curved portion (24a) is the part where the collecting portion (24) is bent along the y-direction. The collecting portion (24) is bent at approximately a right angle from the curved portion (24a). Because of this, in the xz cross-section, the plate-like portion (24b) is extended along the stacking direction of the electrode stack (22). The plate-like portion (24b) extends upward from the curved portion (24a) along the side (22a) of the electrode laminate (22) (i.e., toward the center C1). The leading edge of the plate-like portion (24b) is located below the center C1.

[0030] The electrode plate (50) is a metal plate having a curved portion (54). The curved portion (54) is a part where the electrode plate (50) is bent along the y-direction. The electrode plate (50) is bent at approximately a right angle at the curved portion (54). Because of this, the electrode plate (50) has an L-shape in the xz cross-section. The electrode plate (50) has a plate portion (51) and a plate portion (52) on both sides of the curved portion (54). That is, the plate portion (52) is connected to the plate portion (51) through the curved portion (54). The plate portion (51) is extended along the z-direction and is arranged along the plate portion (24b) of the collecting portion (24). The plate portion (51) is in contact with the outer side of the plate portion (24b). In the joint portion (40) where the plate portion (51) and the plate-shaped portion (24b) are in contact, the plate portion (51) is joined to the plate-shaped portion (24b). The curved portion (54) is provided at the top of the plate portion (51). The plate portion (52) is extended from the curved portion (54) in the x-direction toward the electrode laminate (22). The plate portion (52) is positioned at the center C1. That is, the plate portion (52) is extended in the x-direction at a position overlapping with the center C1. The plate portion (52) is extended from the inside to the outside of the outer body (30) through the interface between the frame portion (36a) and the frame portion (34a). The welded portion (70) is provided at a position overlapping with the plate portion (52). In the welded portion (70), a frame portion (36a) is welded to the upper surface of the plate portion (52), and a frame portion (34a) is welded to the lower surface of the plate portion (52).

[0031] FIG. 5 illustrates the connection structure between the electrode plate (50) and the collecting portion (24) of a battery cell of a comparative example. In the battery cell of the comparative example, the collecting portion (24) is extended in a straight line along the x-direction from the side (22a) of the electrode stack (22). Additionally, the electrode plate (50) has a flat plate shape that extends along the x-direction, and the lower end surface of the electrode plate (50) is in contact with the upper surface of the collecting portion (24). In the joint portion (40) where the electrode plate (50) and the collecting portion (24) are in contact, the electrode plate (50) is joined to the collecting portion (24). The electrode plate (50) is extended from the inside to the outside of the outer body (30) through the interface between the frame portion (36a) and the frame portion (34a). The weld portion (70) is positioned further outward than the joint portion (40).

[0032] In the configuration of the comparative example of FIG. 5, the joint portion (40) is extended in the x-direction, so the dimensions of the electrode plate (50) in the x-direction are large. That is, the distance L1 from the side (22a) of the electrode stack (22) to the leading edge of the electrode plate (50) is long. In contrast, in the configuration of the embodiment shown in FIG. 3, the joint portion (40) is extended along the z-direction, so the dimensions of the electrode plate (50) in the x-direction are smaller than those of FIG. 5. That is, the distance L1 from the side (22a) of the electrode stack (22) to the leading edge of the electrode plate (50) is short. Thus, according to the configuration of the embodiment, the dimensions of the electrode plate in the x-direction can be reduced, and thus the battery cell (10) can be miniaturized. For this reason, when a battery module is formed by stacking a plurality of battery cells (10), the size of the battery module can be reduced. Therefore, the battery module can accumulate power with high energy density.

[0033] In addition, according to the configuration of the embodiment, since the collecting portion (24) is connected to the side (22a) of the electrode stack (22) at a position offset from the center C1, the plate portion (52) of the electrode plate (50) can be placed at the center C1.

[0034] Next, a method for manufacturing a battery cell (10) is described. First, the entire assembly (20) is assembled as shown in FIG. 6. In this step, the collecting portion (24) is extended in a straight line along the x-direction from the side (22a) of the electrode stack (22). Next, the plate portion (51) of the L-shaped electrode plate (50) is brought into contact with the lower surface of the collecting portion (24), and the plate portion (51) is joined to the collecting portion (24) by laser welding or the like. Next, as shown in FIG. 3, the collecting portion (24) is bent so that the plate portion (52) becomes parallel to the x-direction. After that, the entire assembly (20) is housed in an outer body (30), and the outer body (30) is welded with a welding portion (70) to complete the battery cell (10). According to this method, the battery cell (10) can be easily manufactured.

[0035] In addition, in the above embodiment, the plate portion (51) of the electrode plate (50) was attached to the outer side of the collecting portion (24). However, as shown in FIG. 7, the plate portion (51) may be attached to the inner side of the collecting portion (24). Even with this configuration, the battery cell (10) can be miniaturized.

[0036] Additionally, in the above embodiment, the plate portion (52) was positioned at the center C1. However, in other embodiments, the plate portion (52) may be positioned at a location offset from the center C1. For example, the collecting portion (24) may be positioned at the center C1, and the plate portion (52) may be positioned at a location offset from the center C1.

[0037] In addition, in the above embodiment, in the xz cross section, the plate portion (51) and the plate-shaped portion (24b) were extended parallel to the stacking direction (i.e., z direction) of the electrode stack (22). However, the plate portion (51) and the plate-shaped portion (24b) may be extended along a direction having a predetermined angle (e.g., an angle of 45 degrees or less) with respect to the stacking direction. In addition, in the above embodiment, in the xz cross section, the plate portion (52) was extended parallel to a direction perpendicular to the stacking direction (i.e., x direction). However, the plate portion (52) may be extended along a direction having a predetermined angle (e.g., an angle of 45 degrees or less) with respect to the x direction. Even with these configurations, the battery cell can be miniaturized.

[0038] The curved portion (24a) of the embodiment is an example of the first curved portion. The plate-shaped portion (24b) of the embodiment is an example of a specific portion. The plate portion (51) of the embodiment is an example of the first plate portion. The curved portion (54) of the embodiment is an example of the second curved portion. The plate portion (52) of the embodiment is an example of the second plate portion.

[0039] Although embodiments have been described in detail above, they are merely examples and do not limit the scope of the patent claims. The technology described in the patent claims includes various modifications and alterations of the specific embodiments exemplified above. The technical elements described in this specification or drawings demonstrate technical utility either individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and possesses technical utility in itself by achieving one of those objectives.

Claims

Claim 1 A battery cell having a capacitor and an electrode plate, wherein the capacitor comprises an electrode stack in which a plurality of positive electrode current collectors and a plurality of negative electrode current collectors are stacked, and a collecting portion that bundles the positive electrode current collectors or the negative electrode current collectors, the collecting portion protruding from the side of the electrode stack, wherein the collecting portion has a first bend and a specific portion that is connected to the electrode stack through the first bend and extends along the stacking direction of the electrode stack, and the electrode plate has a first plate portion that is arranged along the specific portion and is bonded to the specific portion, a second bend and a second plate portion that is connected to the first plate portion through the second bend and extends from the second bend in a direction spaced apart from the electrode stack. Claim 2 A battery cell according to claim 1, wherein the collecting portion is connected to the side of the electrode stack at a position offset from the center of the electrode stack in the stacking direction, and the second plate portion is disposed at the center of the electrode stack in the stacking direction. Claim 3 A battery cell according to claim 1 or 2, further comprising a film material surrounding the entire shaft, wherein the film material is welded to the second plate portion.

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