JP7600422B2 - battery - Google Patents

Description

An embodiment of the present invention relates to a battery.

With the advancement of electronic devices such as mobile phones and personal computers, there is a demand for smaller and lighter batteries, such as secondary batteries, used in these electronic devices. Lithium-ion secondary batteries are an example of a secondary battery that is small, lightweight, and has a high energy density. Meanwhile, secondary batteries such as lead-acid batteries and nickel-metal hydride batteries are used as large, high-capacity power sources to be installed in vehicles such as electric cars, hybrid cars, electric motorcycles, and forklifts. In recent years, lithium-ion secondary batteries with high energy density have been developed for use as large, high-capacity power sources to be installed in vehicles. In the development of lithium-ion secondary batteries to be installed in vehicles, there is a demand for larger and larger capacity batteries while also achieving longer battery life and improved safety.

Some batteries, such as lithium ion secondary batteries, have an electrode group housed in the internal cavity of an outer container. In this battery, the outer container has a bottom wall and a peripheral wall, and the internal cavity of the outer container opens on the opposite side to the bottom wall in the height direction. A lid member is attached to the peripheral wall of the outer container, and the opening of the internal cavity is closed by the lid member. In the battery, the electrode terminals are disposed on the outer surface of the lid member in a state where they are exposed to the outside. In the internal cavity, current collecting tabs of the electrode group protrude outward in a horizontal direction that intersects with the height direction. A lead electrically connects the current collecting tabs of the electrode group and the electrode terminals.

In the above-mentioned batteries, it is required to increase the capacity of the battery by increasing the volume of the electrode group, for example by increasing the space occupied by the electrode group in the internal cavity. It is also required to increase the capacity of the battery without increasing the electrical resistance in the electrical path between the electrode group and the electrode terminal, for example by increasing the volume of the electrode group without reducing the cross-sectional area of the leads.

Japanese Patent Application Publication No. 2014-7036 Japanese Patent Application Publication No. 2006-93122

The problem that the present invention aims to solve is to provide a battery that can increase capacity without increasing the electrical resistance in the electrical path between the electrode group and the electrode terminal.

According to an embodiment, the battery includes an outer container, a cover member, an electrode group, an electrode terminal, and a lead. The outer container includes a bottom wall and a peripheral wall, and an internal cavity is formed in the outer container that opens to the side opposite to the side where the bottom wall is located in the height direction. The cover member is attached to the peripheral wall of the outer container in a state where it closes the opening of the internal cavity. The electrode group includes a current collecting tab that protrudes outward in a lateral direction intersecting with the height direction, and is stored in the internal cavity of the outer container. The electrode terminal is exposed to the outside at the outer surface of the cover member, and the lead electrically connects between the current collecting tab of the electrode group and the electrode terminal. The lead includes a top plate portion and a leg plate portion. The top plate portion is disposed between the cover member and the electrode group in the internal cavity, and the electrode terminal is connected to the top plate portion. The leg plate portion is bent with respect to the top plate portion toward the side where the bottom wall is located, and is joined to the current collecting tab. The top plate portion includes an inner edge surface that forms an inner end of the top plate portion in the lateral direction, an underside surface that faces the electrode group, and a recess that is recessed in the underside surface of the top plate toward the side opposite the side on which the electrode group is located. The recess is formed continuously from the inner edge surface of the top plate toward the outside in the lateral direction beyond the connection position of the electrode terminal to the top plate portion. The thickness of the top plate portion in the region where the recess is formed is thinner than the thickness of the top plate portion in the region other than the region where the recess is formed and the thickness of the leg plate portion.

FIG. 1 is a perspective view showing a battery according to a first embodiment, disassembled into its individual components. FIG. 2 is a perspective view showing the battery according to the first embodiment. FIG. 3 is a perspective view that shows a schematic configuration of the leads of the battery according to the first embodiment. FIG. 4 is a cross-sectional view that shows, in the battery according to the first embodiment, a cross section that passes through a position laterally inwardly spaced from a through hole of a lead and is perpendicular or substantially perpendicular to the horizontal direction. FIG. 5 is a cross-sectional view that generally illustrates a cross section passing through a through-hole of a lead and perpendicular or substantially perpendicular to the lateral direction in the battery according to the first embodiment. FIG. 6 is a perspective view that shows a schematic configuration of the leads of the battery according to the first modified example. FIG. 7 is a perspective view that shows a schematic configuration of the leads of a battery according to a second modified example.

The following describes the embodiments with reference to the drawings.

First Embodiment
1 and 2 show a battery 1 according to a first embodiment. As shown in FIG. 1 and FIG. 2, the battery 1 includes an electrode group 2, an outer container 3, and a lid member 5. The outer container 3 and the lid member 5 are each formed of a metal such as aluminum, an aluminum alloy, iron, copper, or stainless steel. Here, in the battery 1 (outer container 3), a depth direction (direction indicated by arrows X1 and X2), a lateral direction (direction indicated by arrows Y1 and Y2) intersecting (perpendicular or substantially perpendicular) with respect to the depth direction, and a height direction (direction indicated by arrows Z1 and Z2) intersecting (perpendicular or substantially perpendicular) with respect to both the depth direction and the lateral direction are defined. In each of the battery 1 and the outer container 3, the dimension in the depth direction is smaller than the dimension in the lateral direction and the dimension in the height direction. Note that FIG. 1 is a perspective view showing each member disassembled, and FIG. 2 is a perspective view.

The outer container 3 has a bottom wall 6 and a peripheral wall 7. The internal cavity 8 in which the electrode group 2 is stored is defined by the bottom wall 6 and the peripheral wall 7. In the outer container 3, the internal cavity 8 opens toward the opposite side to the side where the bottom wall 6 is located in the height direction. The peripheral wall 7 has two pairs of side walls 11, 12. The pair of side walls 11 face each other in the horizontal direction, sandwiching the internal cavity 8 therebetween. The pair of side walls 12 face each other in the depth direction, sandwiching the internal cavity 8 therebetween. Each of the side walls 11 extends continuously between the side walls 12 along the depth direction. Each of the side walls 12 extends continuously between the side walls 11 along the horizontal direction. The lid member 5 is attached to the peripheral wall 7 at the end opposite the bottom wall 6. Therefore, the lid member 5 closes the opening of the internal cavity 8 of the outer container 3. The lid member 5 and the bottom wall 6 face each other in the height direction, sandwiching the internal cavity 8 therebetween.

The electrode group 2 includes a negative electrode 13A and a positive electrode 13B. In the electrode group 2, a separator (not shown) is interposed between the negative electrode 13A and the positive electrode 13B. The separator is made of an electrically insulating material and electrically insulates the negative electrode 13A from the positive electrode 13B.

The negative electrode 13A comprises a negative electrode collector such as a negative electrode collector foil, and a negative electrode active material-containing layer (not shown) supported on the surface of the negative electrode collector. The negative electrode collector is, but is not limited to, for example, aluminum foil, aluminum alloy foil, or copper foil, and has a thickness of about 10 μm to 20 μm. The negative electrode active material-containing layer comprises a negative electrode active material, and may optionally contain a binder and a conductive agent. The negative electrode active material is, but is not limited to, a metal oxide, a metal sulfide, a metal nitride, a carbon material, and the like that can absorb and release lithium ions. The negative electrode collector comprises a negative electrode collector tab 15A as a portion that does not support the negative electrode active material-containing layer.

The positive electrode 13B comprises a positive electrode collector such as a positive electrode collector foil, and a positive electrode active material-containing layer (not shown) supported on the surface of the positive electrode collector. The positive electrode collector is, but is not limited to, for example, an aluminum foil or an aluminum alloy foil, and has a thickness of about 10 μm to 20 μm. The positive electrode active material-containing layer comprises a positive electrode active material, and may optionally contain a binder and a conductive agent. Examples of the positive electrode active material include, but are not limited to, oxides, sulfides, and polymers that can absorb and release lithium ions. The positive electrode collector comprises a positive electrode collector tab 15B as a portion that does not support the positive electrode active material-containing layer.

In one example of the electrode group 2 shown in FIG. 1, the negative electrode 13A, the positive electrode 13B, and the separator are wound around the winding axis W with the separator sandwiched between the negative electrode active material-containing layer and the positive electrode active material-containing layer. In another example, the electrode group 2 has a stack structure in which a plurality of negative electrodes 13A and a plurality of positive electrodes 13B are alternately stacked, and a separator is provided between the negative electrode 13A and the positive electrode 13B. In the electrode group 2, the negative electrode current collector tab 15A protrudes relative to the positive electrode 13B and the separator. And the positive electrode current collector tab 15B protrudes relative to the negative electrode 13A and the separator in the opposite direction to the protruding direction of the negative electrode current collector tab 15A. In one example such as FIG. 1, a pair of current collector tabs 15 (negative electrode current collector tab 15A and positive electrode current collector tab 15B) protrude in opposite directions from each other in the axial direction along the winding axis W (directions indicated by arrows Y3 and Y4).

In addition, in the electrode group 2, the negative electrode current collector tab 15A protrudes from the negative electrode active material-containing layer, and the positive electrode current collector tab 15B protrudes from the side opposite to the side from which the negative electrode current collector tab 15A protrudes from the positive electrode active material-containing layer. Therefore, the boundary position Ba between the negative electrode current collector tab 15A (part not carrying the negative electrode active material-containing layer) and the negative electrode active material-containing layer is the base position of the protruding part of the negative electrode current collector tab 15A from the negative electrode active material-containing layer, and is the end (coated end) of the negative electrode active material-containing layer on the side where the negative electrode current collector tab 15A is located. And the boundary position Bb between the positive electrode current collector tab 15B (part not carrying the positive electrode active material-containing layer) and the positive electrode active material-containing layer is the base position of the protruding part of the positive electrode current collector tab 15B from the positive electrode active material-containing layer, and is the end (coated end) of the positive electrode active material-containing layer on the side where the positive electrode current collector tab 15B is located. In addition, in the region between boundary positions Ba and Bb in the axial direction along the winding axis W (the protruding direction of the pair of current collecting tabs 15), a negative electrode active material-containing layer is supported (coated) on the surface of the negative electrode current collector, and a positive electrode active material-containing layer is supported (coated) on the surface of the positive electrode current collector.

In the electrode group 2, a width direction (direction indicated by arrows Z3 and Z4) that intersects (orthogonal or nearly orthogonal) with the protruding direction of the current collecting tab 15 (axial direction of the winding axis W), and a thickness direction (direction indicated by arrows X3 and X4) that intersects both the protruding direction and the width direction of the current collecting tab 15 are specified. In the electrode group 2, the dimension in the thickness direction is smaller than the dimension in the axial direction and the dimension in the width direction. For this reason, the electrode group 2 is formed in a flat shape. In addition, in each of a pair of current collecting tabs 15, multiple strip-shaped portions are bundled together.

In this embodiment, the electrode group 2 is arranged in the internal cavity 8 with the width direction coinciding or approximately coinciding with the height direction of the battery 1 and the thickness direction coinciding or approximately coinciding with the depth direction of the battery 1. In one example of FIG. 1, the electrode group 2 is arranged in the internal cavity 8 with the winding axis W aligned along the lateral direction of the battery 1. Each of the pair of current collector tabs 15 protrudes outward in the lateral direction of the battery 1 in the electrode group 2. The negative electrode current collector tab 15A protrudes toward one lateral side of the battery 1 relative to the positive electrode 13B and the separator, and protrudes toward one lateral side from the boundary position Ba with the negative electrode active material-containing layer. In addition, the positive electrode current collector tab 15B protrudes toward the negative electrode 13A and the separator, etc., in the lateral direction of the battery 1, on the opposite side to the side from which the negative electrode current collector tab 15A protrudes, and protrudes toward the other lateral side from the boundary position Bb with the positive electrode active material-containing layer.

1, the electrode group 2 is wound around the winding axis W along the lateral direction of the battery 1 as described above. Therefore, in the electrode group 2, a curved surface 14 is formed on the outer surface of one end in the width direction. In the battery 1, the curved surface 14 forms the end of the electrode group 2 on the side where the lid member 5 is located, and becomes the end face of the electrode group 2 on the side where the lid member 5 is located. That is, in the electrode group 2, the curved surface 14 is formed by the outer surface of the end on the side where the lid member 5 is located. The curved surface 14 is formed in a part of the electrode group 2 different from the current collecting tabs 15 (15A, 15B), and is formed, for example, between the boundary positions Ba and Bb in the lateral direction of the battery 1. In a cross section perpendicular or substantially perpendicular to the lateral direction of the battery 1 (the axial direction of the electrode group 2), the curved surface 14 is arc-shaped.

In addition, in the internal cavity 8, an electrolyte (not shown) is retained (impregnated) in the electrode group 2. The electrolyte may be a non-aqueous electrolyte in which an electrolyte is dissolved in an organic solvent, or an aqueous electrolyte such as an aqueous solution. Instead of the electrolyte, a gel electrolyte or a solid electrolyte may be used. When a solid electrolyte is used as the electrolyte, the solid electrolyte is interposed between the negative electrode 13A and the positive electrode 13B in the electrode group instead of a separator. In this case, the negative electrode 13A is electrically insulated from the positive electrode 13B by the solid electrolyte.

In the battery 1, a pair of electrode terminals 16 are attached to the cover member 5. The electrode terminals 16 are formed from a conductive material such as metal. One of the electrode terminals 16 is the negative terminal (16A) of the battery 1, and the other of the pair of electrode terminals 16 is the positive terminal (16B) of the battery 1. Each of the electrode terminals 16 is disposed on the outer surface of the cover member 5 in a state where it is exposed to the outside of the battery 1. The pair of electrode terminals 16 are disposed apart from each other in the lateral direction of the battery 1.

The lid member 5 is also provided with a pair of through holes 17. Each of the through holes 17 penetrates the lid member 5 along the height direction of the battery 1. On the outer surface of the lid member 5, an insulating member 18 is provided between each of the electrode terminals 16 and the lid member 5. An insulating gasket 19 is also disposed in each of the through holes 17. Each of the electrode terminals 16 is electrically insulated from the lid member 5 and the outer container 3 by the insulating member 18 and the insulating gasket 19.

A pair of leads 20 are arranged in the internal cavity 8 of the outer container 3. One of the pair of leads 20 is a negative electrode side lead (20A), and the other of the pair of leads 20 is a positive electrode side lead (20B). The negative electrode side lead 20A forms at least a part of the electrical path between the negative electrode current collector tab 15A and the negative electrode terminal 16A. Therefore, the negative electrode side lead 20A electrically connects between the negative electrode current collector tab 15A and the negative electrode terminal 16A of the electrode group 2. In addition, the positive electrode side lead 20B forms at least a part of the electrical path between the positive electrode current collector tab 15B and the positive electrode terminal 16B. Therefore, the positive electrode side lead 20B electrically connects between the positive electrode current collector tab 15B and the positive electrode terminal 16B of the electrode group 2. Each of the leads 20 is formed from a conductive material such as a metal. Examples of conductive materials for forming the leads 20 include aluminum, stainless steel, copper, and iron.

In addition, a pair of insulating guards 21 and a pair of insulating tapes 22 are arranged in the internal cavity 8 of the outer container 3. Each of the insulating guards 21 and the insulating tapes 22 is formed of an electrically insulating material. The insulating guard 21A, which is one of the insulating guards 21, is arranged between the negative electrode side lead 20A (negative electrode current collector tab 15A) and the peripheral wall 7 of the outer container 3. The insulating guard 21A prevents the negative electrode side lead 20A and the negative electrode current collector tab 15A from contacting the outer container 3, and electrically insulates them from the outer container 3. The insulating guard 21B, which is the other of the insulating guards 21A, is arranged between the positive electrode side lead 20B (positive electrode current collector tab 15B) and the peripheral wall 7 of the outer container 3. The insulating guard 21B prevents the positive electrode side lead 20B and the positive electrode current collector tab 15B from contacting the outer container 3, and electrically insulates them from the outer container 3. Each of the insulating guards 21 is fixed to the electrode group 2 by a corresponding one of the insulating tapes 22 .

The electrode group presser 23 is disposed between the electrode group 2 and the lid member 5 in the height direction of the battery 1. The electrode group presser (internal insulating member) 23 is formed from an electrically insulating material. The pair of current collecting tabs 15 and the pair of leads 20 are prevented from contacting the lid member 5 by the electrode group presser 23, and are electrically insulated from the lid member 5. The electrode group presser 23 is also provided with a pair of through holes 25. Each of the through holes 25 penetrates the electrode group presser 23 along the height direction of the battery 1.

1 and 2, a gas release valve 26 and a liquid inlet 27 are formed in the cover member 5. A sealing plate 28 that closes the liquid inlet 27 is welded to the outer surface of the cover member 5. The gas release valve 26 and the liquid inlet 27 are disposed between a pair of electrode terminals 16 in the lateral direction of the battery 1. Note that in one example, the gas release valve 26 and the liquid inlet 27, etc. do not have to be provided in the battery 1.

Figure 3 shows the configuration of the lead 20. In one example of Figures 1 and 3, each of the pair of leads 20 (20A, 20B) has a top plate portion 31 and a pair of leg plate portions 32, 33. In each top plate portion 31 of the lead 20, a plate length direction (direction indicated by arrows Y5 and Y6), a plate width direction (direction indicated by arrows X5 and X6) that intersects (orthogonal or approximately orthogonal) with respect to the plate length direction, and a plate thickness direction (direction indicated by arrows Z5 and Z6) that intersects (orthogonal or approximately orthogonal) with respect to both the plate length direction and the plate width direction are defined. Each top plate portion 31 of the lead 20 has edge surfaces E1 to E4. In each of the top plate portions 31, the edge surface E1 forms an end on one side in the plate length direction, and the edge surface E2 forms an end opposite the edge surface E1 in the plate length direction. In each of the top plate portions 31, an end on one side in the plate width direction is formed by the edge surface E3, and an end on the opposite side to the edge surface E3 in the plate width direction is formed by the edge surface E4. In each of the leads 20, the edge surfaces E1 and E2 extend along the plate width direction between the edge surfaces E3 and E4, and the edge surfaces E3 and E4 extend along the plate length direction between the edge surfaces E1 and E2.

Therefore, in each of the leads 20, the top plate portion 31 extends continuously from the edge surface E1 to the edge surface E2 along the plate length direction, and from the edge surface E3 to the edge surface E4 along the plate width direction. Each of the top plate portions 31 also has a top plate lower surface 35 and a top plate upper surface 36. In each of the top plate portions 31, the top plate lower surface 35 faces one side in the plate thickness direction, and the top plate upper surface 36 faces the opposite side to the top plate lower surface 35 in the plate thickness direction. In each of the leads 20, the dimension between the top plate lower surface 35 and the top plate upper surface 36 is defined as the plate thickness of the top plate portion 31. In each of the leads 20, a through hole 37 is formed that penetrates the top plate portion 31 along the plate thickness direction from the top plate upper surface 36 to the top plate lower surface 35.

In each of the leads 20, each of the pair of leg plate portions 32, 33 is connected to the top plate portion 31 at a position opposite the edge surface E1 with respect to the through hole 37 in the plate length direction of the top plate portion 31, i.e., between the through hole 37 and the edge surface E2 in the plate length direction of the top plate portion 31. In an example such as FIG. 1 and FIG. 3, in each of the top plate portions 31 of the leads 20, the leg plate portion 32 is connected to the end of the edge surface E3 on the side where the edge surface E2 is located, and the leg plate portion 33 is connected to the end of the edge surface E4 on the side where the edge surface E2 is located. In each of the leads 20, each of the leg plate portions 32, 33 is bent with respect to the top plate portion 31 toward one side in the plate thickness direction of the top plate portion 31, i.e., toward the side where the top plate lower surface 35 faces. In the example shown in FIGS. 1 and 3 , in each of the leads 20 , the bending lines at the bending positions of the leg plate portions 32 , 33 relative to the top plate portion 31 are aligned along the plate length direction of the top plate portion 31 .

In each of the leads 20, the leg plate portions 32, 33 extend from the connection position (the bending position relative to the top plate portion 31) to the side facing the top plate underside 35, and the leg plate portions 32, 33 are spaced apart from each other in the plate width direction of the top plate portion 31. In each of the leads 20, the plate length direction, the plate width direction intersecting (perpendicular or approximately perpendicular) with the plate length direction, and the plate thickness direction intersecting (perpendicular or approximately perpendicular) with both the plate length direction and the plate width direction are also specified for each of the leg plate portions 32, 33. In one example such as Figures 1 and 3, in each lead 20, the plate length direction of each of the leg plate portions 32, 33 coincides or approximately coincides with the plate thickness direction of the top plate portion 31, the plate width direction of each of the leg plate portions 32, 33 coincides or approximately coincides with the plate length direction of the top plate portion 31, and the plate thickness direction of each of the leg plate portions 32, 33 coincides or approximately coincides with the plate width direction of the top plate portion 31.

Each of the leads 20 is arranged in the internal cavity 8 with the plate thickness direction of the top plate portion 31 coinciding or approximately coinciding with the height direction of the battery 1, and the plate width direction of the top plate portion 31 coinciding or approximately coinciding with the depth direction of the battery 1. In the internal cavity 8, the top plate portion 31 of each of the leads 20 is arranged between the cover member 5 and the electrode group 2 in the height direction of the battery 1, and between the electrode group presser 23 and the electrode group 2 in the height direction of the battery 1. Therefore, the electrode group presser 23 is arranged between the top plate portion 31 of each of the leads 20 and the cover member 5. In each of the leads 20 arranged in the internal cavity 8, the edge surface E2 of the top plate portion 30 is arranged laterally outside the battery 1 with respect to the edge surface E1. Therefore, in each lead 20, edge surface E1 becomes the top plate inner edge surface that forms the inner end of the top plate portion 31 in the lateral direction of the battery 1, and edge surface E2 becomes the top plate outer edge surface that forms the outer end of the top plate portion 31 in the lateral direction of the battery 1. Therefore, in the internal cavity 8, each top plate portion 31 extends laterally outward from edge surface (top plate inner edge surface) E1 to edge surface (top plate outer edge surface) E2.

In each of the leads 20 arranged in the internal cavity 8, the top plate underside 35 of the top plate portion 31 faces the electrode group 2 in the height direction of the battery 1, and faces the electrode group 2. In each of the leads 20, the top plate underside 35 of the top plate portion 31 faces the electrode group 2 from the side where the lid member 5 is located. In each of the leads 20, the top plate upper side 36 faces the side where the lid member 5 is located in the height direction of the battery 1, and faces the lid member 5 with the electrode group presser 23 sandwiched therebetween. In each of the leads 20, a corresponding one of the electrode terminals 16 is connected through the through hole 37. Therefore, in each of the leads 20, the through hole 37 is the connection position of the corresponding one of the electrode terminals 16. Each of the pair of electrode terminals 16 is inserted in order through the corresponding one of the through holes 17, the corresponding one of the through holes 25, and the corresponding one of the through holes 37. Each of the electrode terminals 16 is connected to a corresponding one of the top plate portions 31 of the leads 20 by crimping or the like. Also, in each of the electrode terminals 16, a portion crimped by crimping (a plastically deformed portion) is joined to a top plate undersurface 35 of the corresponding one of the top plate portions 31 of the leads 20 by ultrasonic welding or the like.

In addition, in each of the leads 20 arranged in the internal cavity 8, the pair of leg plate portions 32, 33 are located outside the through hole 37 (the connection position of the electrode terminal 16) in the lateral direction of the battery 1, and each of the leg plate portions 32, 33 is connected to the top plate portion 31 at a position outside the connection position of the electrode terminal 16 in the lateral direction of the battery 1. In each of the leads 20, the pair of leg plate portions 32, 33 are arranged apart from each other in the depth direction of the battery 1. In each of the leads 20, each of the leg plate portions 32, 33 extends from the connection position to the top plate portion 31 (the bending position relative to the top plate portion 31) along the height direction of the battery 1, and bends toward the side where the bottom wall 6 is located relative to the top plate portion 31. In one example such as FIG. 1 and FIG. 3, in each of the leads 20, the bending lines at the bending positions of the leg plate portions 32, 33 relative to the top plate portion 31 are along the lateral direction of the battery 1.

In each of the leads 20, the leg plate portion 32 has a pair of leg main surfaces 41, 42, and the leg plate portion 33 has a pair of leg main surfaces 43, 44. In each of the leg plate portions 32 of the leads 20, the leg main surface 41 faces inward in the depth direction of the battery 1 and faces one side in the plate thickness direction of the leg plate portion 32. In each of the leg plate portions 32 of the leads 20, the leg main surface 42 faces the opposite side to the leg main surface 41 in the depth direction of the battery 1 (plate thickness direction of the leg plate portion 32) and faces outward in the depth direction of the battery 1. In each of the leads 20, at the connection position of the leg plate portion 32 to the top plate portion 31, the leg main surface 41 is connected to the top plate lower surface 35, and the leg main surface 42 is connected to the top plate upper surface 36. Furthermore, in each leg plate portion 33 of the lead 20, the leg main surface 43 faces inward in the depth direction of the battery 1, and faces one side in the plate thickness direction of the leg plate portion 33. And, in each leg plate portion 33 of the lead 20, the leg main surface 44 faces the opposite side to the leg main surface 43 in the depth direction of the battery 1 (plate thickness direction of the leg plate portion 33), and faces outward in the depth direction of the battery 1. In each lead 20, at the connection position of the leg plate portion 33 to the top plate portion 31, the leg main surface 43 is connected to the top plate lower surface 35, and the leg main surface 44 is connected to the top plate upper surface 36.

Therefore, in each of the leads 20, the leg main surface 42 of the leg plate portion 32 and the leg main surface 44 of the leg plate portion 33 face the side where the peripheral wall 7 (the corresponding one of the side walls 12) is located, and face the outer periphery of the internal cavity 8. In each of the leads 20, the leg main surface 41 of the leg plate portion 32 and the leg main surface 43 of the leg plate portion 33 face the inner periphery of the internal cavity 8, and face the side where the electrode group 2 is located. In each of the leads 20, the leg main surfaces 41 and 43 face each other with a corresponding one of the pair of current collecting tabs 15 sandwiched therebetween. In each of the leads 20, the dimension between the leg main surfaces 41 and 42 is defined as the plate thickness of the leg plate portion 32, and the dimension between the leg main surfaces 43 and 44 is defined as the plate thickness of the leg plate portion 33.

In each of the leads 20, the leg plate portion 32 has edge surfaces (leg edge surfaces) E5 and E6, and the leg plate portion 33 has edge surfaces (leg edge surfaces) E7 and E8. In each of the leg plate portions 32, the edge surface E5 forms one end of the leg plate portion 32 in the plate width direction, and forms the inner end of the leg plate portion 32 in the lateral direction of the battery 1. In each of the leg plate portions 32, the edge surface E6 forms the end opposite the edge surface E5 in the lateral direction of the battery 1 (plate width direction of the leg plate portion 32), and forms the outer end of the leg plate portion 32 in the lateral direction of the battery 1. For this reason, in each of the leads 20, each of the leg main surfaces 41 and 42 extends outward in the lateral direction from the edge surface E5 to the edge surface E6, and the leg plate portion 32 extends outward in the lateral direction from the edge surface E5 to the edge surface E6.

In addition, in each of the leg plate portions 33, the edge surface E7 forms one end of the leg plate portion 33 in the plate width direction, and forms the inner end of the leg plate portion 33 in the lateral direction of the battery 1. In each of the leg plate portions 33, the edge surface E8 forms the end opposite the edge surface E7 in the lateral direction of the battery 1 (plate width direction of the leg plate portion 33), and forms the outer end of the leg plate portion 33 in the lateral direction of the battery 1. For this reason, in each of the leads 20, each of the leg main surfaces 43, 44 extends laterally outward from the edge surface E7 to the edge surface E8, and the leg plate portion 33 extends laterally outward from the edge surface E7 to the edge surface E8.

In one example such as FIG. 1, two bundling portions are formed in each of the current collecting tabs 15, where a plurality of strip-shaped portions are bundled. Two pairs of backup leads 46, 47 are also arranged in the internal cavity 8. Each of the backup leads 46, 47 is made of a conductive material such as metal. In each of the current collecting tabs 15, one of the two bundling portions is sandwiched between a corresponding one of the pair of backup leads 46. In each of the current collecting tabs 15, one of the two bundling portions is joined to the leg main surface 41 of the corresponding one of the leg plate portions 32 of the lead 20, with the corresponding one of the backup leads 46 interposed therebetween. In each of the current collecting tabs 15, the other of the two bundling portions is sandwiched between a corresponding one of the pair of backup leads 47. In each of the current collecting tabs 15 , the other of the two binding portions is joined to the leg main surface 43 of the leg plate portion 33 of a corresponding one of the leads 20 , with a corresponding one of the backup leads 47 interposed therebetween.

In each of the current collecting tabs 15, one of the two binding parts is joined to the corresponding leg plate portion 32 of the lead 20, for example, by ultrasonic welding, and the other of the two binding parts is joined to the corresponding leg plate portion 33 of the lead 20, for example, by ultrasonic welding. Also, the backup leads 46, 47 do not have to be provided. In one example, in each of the current collecting tabs 15, one of the two binding parts is directly joined to the leg main surface 41 of the corresponding leg plate portion 32 of the lead 20 without the backup lead 46 or the like being interposed therebetween. And, in each of the current collecting tabs 15, the other of the two binding parts is directly joined to the leg main surface 43 of the corresponding leg plate portion 33 of the lead 20, without the backup lead 47 or the like being interposed therebetween.

4 and 5 show one of the pair of leads 20, the electrode group 2, and the configuration in the vicinity thereof in a cross section perpendicular or approximately perpendicular to the lateral direction of the battery 1. FIG. 4 shows a cross section passing through a position separated inward in the lateral direction from the through hole 37 (the connection position of one corresponding electrode terminal 16) of the lead 20, and FIG. 5 shows a cross section passing through the through hole 37 (the center or approximately the center of the through hole 37) of the lead 20. As shown in FIGS. 3 to 5, etc., in each of the leads 20, the top plate upper surface 36 of the top plate portion 31 is formed in a planar or approximately planar shape facing the side where the lid member 5 is located in the height direction of the battery 1. In one example, the top plate upper surface 36 of each of the leads 20 is formed parallel or approximately parallel to the inner surface of the lid member 5, and is formed parallel or approximately parallel to the depth direction and lateral direction of the battery 1.

In addition, in each of the leads 20, a recess 50 is formed on the top plate underside 35 of the top plate portion 31, recessed toward the side where the top plate upper surface 36 is located. In each of the leads 20 arranged in the internal cavity 8, the recess 50 formed on the top plate underside 35 is recessed in the height direction toward the side where the lid member 5 is located, and is recessed toward the opposite side to the side where the electrode group 2 is located. Therefore, in each of the leads 20, the recess 50 is recessed toward the opposite side to the side where the electrode group 2 is located, with respect to the portion of the top plate underside 35 other than the recess 50, and with respect to each of the leg main surfaces 41, 43 connected to the top plate underside 35.

On the top plate underside 35 of each top plate portion 31 of the lead 20, the recess 50 is formed from the edge surface (top plate inner edge surface) E1 along the plate length direction toward the side where the edge surface E2 is located. Therefore, in each of the leads 20 arranged in the internal cavity 8, the recess 50 extends from the edge surface E1 toward the outside in the lateral direction of the battery 1 on the top plate underside 35. In each of the leads 20, one end of the recess 50 in the plate length direction is located on the edge surface E1, and the inner end of the recess 50 in the lateral direction of the battery 1 (recess inner end) is located on the edge surface E1.

In addition, each recess 50 of the lead 20 has a recess end surface 51. In each lead 20, the end opposite to the edge surface (top plate inner edge surface) E1 of the recess 50 in the plate length direction is formed by the recess end surface 51. Therefore, in each lead 20, the outer end (outer end of the recess) of the recess 50 in the lateral direction of the battery 1 is formed by the recess end surface 51. In each lead 20, the recess end surface 51 is located on the side where the edge surface E2 is located with respect to the through hole 37 (connection position of the electrode terminal 16), and the recess end surface 51 is located on the outer side with respect to the through hole 37 in the lateral direction of the battery 1. In addition, in this embodiment, in each lead 20, the recess end surface 51 is located on the inner side with respect to the connection position of each of the leg plate portions 32, 33 to the top plate portion 31 in the lateral direction of the battery 1, and is located on the side closer to the edge surface E1 and the through hole 37 with respect to the connection position of each of the leg plate portions 32, 33.

Because of the above-mentioned configuration, in each of the leads 20, the end of the recess 50 opposite the edge surface (top plate inner edge surface) E1, i.e., the end formed by the recess end surface 51 of the recess 50, is located between the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31 and the connection positions of the leg plate portions 32 and 33 to the top plate portion 31 in the lateral direction (plate length direction) of the battery 1. Therefore, in each of the top plate underside surfaces 35 of the leads 20 arranged in the internal cavity 8, the recess 50 is formed continuously from the edge surface (top plate inner edge surface) E1 toward the outside in the lateral direction beyond the connection position of the electrode terminal 16 to the top plate portion 31. In other words, in each of the leads 20, the recess 50 continues from the edge surface E1 toward the outside in the lateral direction to the recess end surface 51 located on the outside in the lateral direction relative to the through hole 37.

In addition, in the top plate underside 35 of each lead 20, a relay portion 52 is formed between the recess end surface 51 of the recess 50 and the edge surface (top plate outer edge surface) E2. In the top plate underside 35 of each lead 20, the relay portion 52 is adjacent to the recess 50 from the lateral outside of the battery 1, and is continuously formed from the recess end surface 51 to the edge surface E2 toward the lateral outside. In each lead 20, the leg main surface 41 of the leg plate portion 32 and the leg main surface 43 of the leg plate portion 33 are connected to the relay portion 52 of the top plate underside 35. In each lead 20, the relay portion 52 of the top plate underside 35 is formed in a planar or approximately planar shape facing the side where the electrode group 2 (bottom wall 6) is located in the height direction of the battery 1. In one example, the relay portion 52 of each lead 20 is formed parallel or approximately parallel to the depth direction and lateral direction of the battery 1.

In addition, adjacent portions 55, 56 are formed on the underside 35 of the top plate of each lead 20. On the underside 35 of the top plate of each lead 20, the adjacent portion (first adjacent portion) 55 is adjacent to the recess 50 from one side in the depth direction of the battery 1 (plate width direction of the top plate portion 31), and the adjacent portion (second adjacent portion) 56 is adjacent to the recess 50 from the opposite side of the adjacent portion 55 in the depth direction of the battery 1. On the underside 35 of the top plate of each lead 20, the adjacent portion 55 is formed continuously from the opening edge A1 of the recess 50 to the edge surface E3 toward the outside in the depth direction of the battery 1 (plate width direction of the lead 20), and the adjacent portion 56 is formed continuously from the opening edge A2 of the recess 50 to the edge surface E4 toward the outside in the depth direction. Furthermore, in each of the leads 20, the adjacent portions 55, 56 of the top plate underside 35 are formed in a planar or substantially planar shape facing the side where the electrode group 2 is located in the height direction of the battery 1. In one example, in each of the leads 20, the adjacent portions 55, 56 are formed parallel or substantially parallel to the depth and width directions of the battery 1.

On the underside 35 of the top plate of each of the leads 20, the recess 50 is recessed toward the opposite side (the side where the cover member 5 is located) from the side where the electrode group 2 is located, relative to each of the relay portion 52 and the adjacent portion 55. Therefore, in each of the leads 20, the recess 50 is sandwiched between the adjacent portions 55, 56 in the depth direction, and is adjacent to the inside of the relay portion 52 in the lateral direction, and is recessed toward the opposite side from the side where the electrode group 2 is located in the height direction.

In each of the leads 20, the recess 50 has a recess bottom surface 57 that forms the bottom of the recess 50. In each of the recesses 50 of the leads 20, the recess bottom surface 57 is continuously formed from the edge surface (top plate inner edge surface) E1 to the recess end surface 51 toward the outside in the lateral direction of the battery 1. Therefore, in each of the recesses 50 of the leads 20, the recess bottom surface 57 is formed along the lateral direction through the through hole 37 (the connection position of the electrode terminal 16 to the top plate portion 31). In each of the leads 20, the recess bottom surface 57 is formed in a planar or approximately planar shape facing the side where the electrode group 2 is located in the height direction of the battery 1. In one example, in each of the leads 20, the recess bottom surface 57 is formed parallel or approximately parallel to the top plate upper surface 36, and is formed parallel or approximately parallel to the depth direction and lateral direction of the battery 1.

In each of the leads 20, the distance from the opening of the recess 50 (adjacent portions 55, 56) to the bottom surface 57 of the recess along the height direction of the battery 1 (the plate thickness direction of the lead 20) is defined as the recess amount of the recess 50. In one example, the recess amount of the recess 50 in each of the leads 20 is about 0.5 mm. Since the recess 50 is formed as described above, in the top plate portion 31 of each of the leads 20, the plate thickness T1 in the area where the recess 50 is formed is thinner than the plate thickness T2 in the area other than the area where the recess is formed (for example, the relay portion 52 and the adjacent portions 55, 56, etc.). In each of the leads 20, the plate thickness T1 of the top plate portion 31 in the area where the recess 50 is formed is thinner than the plate thickness of the leg plate portion 32 and the plate thickness of the leg plate portion 33.

In one example, each of the leads 20 is formed from one plate member. In this case, the leg plate portion 32 that is bent relative to the top plate portion 31 and the leg plate portion 33 that is bent relative to the top plate portion 31 are formed by performing bending processing at corresponding locations on the plate member. In addition, a depression 50 is formed on the top plate underside 35 of the top plate portion 31 by performing press processing at corresponding locations on the plate member. When the depression 50 is formed by press processing as described above, in the top plate portion 31 of each of the leads 20, the hardness in the area where the depression 50 is formed is harder than the hardness in areas other than the area where the depression is formed (for example, the relay portion 52 and the adjacent portions 55, 56, etc.). In each of the leads 20, the hardness of the top plate portion 31 in the area where the depression 50 is formed is harder than the hardness of the leg plate portion 32 and the hardness of the leg plate portion 33. It should be noted that the recess 50 does not necessarily have to be formed by press working, and in one example, the recess 50 may be formed by cutting or the like.

On the underside 35 of the top plate of each lead 20, a step is formed between the relay portion 52 and the bottom surface 57 of the recess by the recess end surface 51. On the underside 35 of the top plate of each lead 20, the step formed by the recess end surface 51 causes the bottom surface 57 of the recess to be shifted by the amount of recession of the recess 50 on the opposite side of the relay portion 52 from the side on which the electrode group 2 is located in the height direction of the battery 1. In one example such as FIG. 3, the recess end surface 51 of each lead 20 is formed in a planar or approximately planar shape facing the inside in the lateral direction of the battery 1, and is formed parallel or approximately parallel to the depth and height directions of the battery 1.

In each of the leads 20, the through hole 37 opens toward the side where the cover member 5 is located on the top plate upper surface 36, and opens toward the side where the electrode group 2 is located on the recess bottom surface 57 of the top plate lower surface 35. Therefore, in the top plate lower surface 35 of each of the leads 20, an opening of the through hole 37 is formed in the recess bottom surface 57 of the recess 50. In each of the leads 20, the recess bottom surface 57 of the recess 50 has an enlarged dimension portion 58, and the dimension of the recess bottom surface 57 along the depth direction of the battery 1 (the plate width direction of the top plate portion 31) is enlarged in the enlarged dimension portion 58 compared to other parts of the recess bottom surface 57 (parts other than the enlarged dimension portion 58). For example, the dimension of the recessed bottom surface 57 along the depth direction of the battery 1 at parts other than the dimensionally enlarged portion 58 is the same or approximately the same as the value (width) W1, and the dimension of the recessed bottom surface 57 along the depth direction of the battery 1 at the dimensionally enlarged portion 58 is larger than the value W1.

3 to 5, etc., in the example, in each recess bottom surface 57 of the lead 20, the dimensionally enlarged portion 58 is formed from position S1 to position S2 in the lateral direction of the battery 1. In each recess bottom surface 57 of the lead 20, position S1 is the inner end of the dimensionally enlarged portion 58 in the lateral direction of the battery 1, and position S2 is the outer end of the dimensionally enlarged portion 58 in the lateral direction of the battery 1. In addition, in each recess bottom surface 57 of the lead 20, the opening of the through hole 37 is formed between positions S1 and S2 in the lateral direction of the battery 1 (plate length direction of the top plate portion 31), and the through hole 37 opens toward the side where the electrode group 2 is located in the dimensionally enlarged portion 58. In each recess bottom surface 57 of the lead 20, the corresponding crimped portion (plastically deformed portion) of the electrode terminal 16 is joined to the dimensionally enlarged portion 58 and joined around the opening of the through hole 37.

3 to 5, in the example, in each of the enlarged dimension portions 58 of the lead 20, the closer to the center of the through hole 37 in the horizontal direction of the battery 1 (the plate length direction of the top plate portion 31), the larger the dimension of the recessed bottom surface 57 along the depth direction of the battery 1. Therefore, in each of the enlarged dimension portions 58 of the lead 20, the closer to the center of the through hole 37 from each of the positions S1 and S2, the larger the dimension (width) of the recessed bottom surface 57 along the depth direction of the battery 1. And, in each of the enlarged dimension portions 58 of the lead 20, at a position passing through the center or approximately the center of the through hole 37 in the horizontal direction of the battery 1, the dimension of the recessed bottom surface 57 along the depth direction of the battery 1 becomes a value (maximum value) W2. Therefore, in each of the enlarged dimension portions 58 of the lead 20, the dimension of the recessed bottom surface 57 along the depth direction of the battery 1 is enlarged from value W1 to value W2 from each of the positions S1 and S2 toward the center of the through hole 37 in the horizontal direction of the battery 1. 4 shows a cross section passing through a position laterally inwardly spaced from the enlarged portion 58 of the bottom surface 57 of the recess of the lead 20, and FIG. 5 shows a cross section passing through the enlarged portion 58 of the bottom surface 57 of the recess of the lead 20.

Each recess 50 of the lead 20 has a pair of inclined surfaces 61, 62 and a pair of step surfaces 65, 66. On the underside 35 of the top plate of each lead 20, each of the inclined surfaces 61, 62 extends continuously from the edge surface E1 to position S1 toward the outside in the lateral direction of the battery 1, and extends continuously from position S2 to the recess end surface 51 toward the outside in the lateral direction of the battery 1. On the underside 35 of the top plate of each lead 20, the inclined surfaces 61, 62 are also formed in the range between positions S1 and S2 in the lateral direction of the battery 1. On the underside 35 of the top plate of each lead 20, the inclined surface (first inclined surface) 61 is formed between the recess bottom surface 57 and the adjacent portion 55 in the depth direction of the battery 1, and is connected to the adjacent portion 55 at the opening edge A1 of the recess 50. In addition, on the underside 35 of each top plate of the lead 20, an inclined surface (second inclined surface) 62 is formed between the bottom surface 57 of the recess and the adjacent portion 56 in the depth direction of the battery 1, and is connected to the adjacent portion 56 at the opening edge A2 of the recess 50.

In each lead 20, the inclined surfaces 61, 62 are inclined in both the depth direction and height direction (the width direction and thickness direction of the top plate portion 31) of the battery 1. In the inclined surface 61 of the top plate underside 35 of each lead 20, the closer to the adjacent portion 55, i.e., the farther from the recessed bottom surface 57, the closer to the electrode group 2 in the height direction of the battery 1. In addition, in the inclined surface 62 of the top plate underside 35 of each lead 20, the closer to the adjacent portion 56, i.e., the farther from the recessed bottom surface 57, the closer to the electrode group 2 in the height direction of the battery 1. On the underside 35 of the top plate of each lead 20, in the range between the edge surface E1 and position S1 in the lateral direction of the battery 1, and in the range between position S2 and the recessed end surface 51 in the lateral direction of the battery 1, the end opposite the adjacent portion 55 of the inclined surface 61 and the end opposite the adjacent portion 56 of the inclined surface 62 are each connected to the recessed bottom surface 57.

In addition, on the underside 35 of each top plate of the lead 20, the dimensions of the inclined surfaces 61, 62 along the depth direction of the battery 1 are smaller in the range between positions S1 and S2 in the horizontal direction of the battery 1 than in the range between edge surface E1 and position S1 in the horizontal direction of the battery 1 and in the range between position S2 and the recessed end surface 51 in the horizontal direction of the battery 1. And on the underside 35 of each top plate of the lead 20, in the range between positions S1 and S2 in the horizontal direction of the battery 1, the dimensions of the inclined surfaces 61, 62 along the depth direction of the battery 1 are reduced by the amount that the dimensions of the recessed bottom surface 57 along the depth direction of the battery 1 are enlarged. In one example, on the underside 35 of each top plate of the lead 20, at a position passing through the center or approximately the center of the through hole 37 in the horizontal direction of the battery 1, that is, at the position where the dimension of the recessed bottom surface 57 along the depth direction of the battery 1 becomes a value (maximum value) W2, the dimensions of each of the inclined surfaces 61, 62 along the depth direction of the battery 1 become zero.

On the underside 35 of each top plate of the lead 20, the step surfaces 65, 66 are formed only in the range between positions S1 and S2 in the horizontal direction of the battery 1 (the plate length direction of the top plate portion 31), and are not formed in the range between the edge surface E1 and position S1 in the horizontal direction of the battery 1, and in the range between position S2 and the recess end surface 51 in the horizontal direction of the battery 1. On the underside 35 of each top plate of the lead 20, in the range between positions S1 and S2 in the horizontal direction of the battery 1, each of the step surfaces 65, 66 is connected to the enlarged portion 58 of the recess bottom surface 57. On the underside 35 of each top plate of the lead 20, the end opposite the dimensionally enlarged portion 58 (recess bottom surface 57) of the step surface (first step surface) 65 is connected to the inclined surface 61 and the adjacent portion 55, and the end opposite the dimensionally enlarged portion 58 (recess bottom surface 57) of the step surface (second step surface) 66 is connected to the inclined surface 62 and the adjacent portion 56.

In one example, in each of the leads 20, the step surfaces 65, 66 are formed in an arc shape centered or approximately centered on the center of the through hole 37 when viewed from the side where the electrode group 2 is located in the height direction of the battery 1. In each of the leads 20, the step surfaces 65, 66 are parallel or approximately parallel to the height direction of the battery 1. Since the inclined surfaces 61, 62 and the step surfaces 65, 66 are formed as described above, in the lower surface 35 of the top plate of each of the leads 20, the recess bottom surface 57 is shifted by the recess amount of the recess 50 on the opposite side to the side where the electrode group 2 is located relative to each of the adjacent portions 55, 56 in the height direction of the battery 1. Furthermore, since the recess bottom surface 57 and the inclined surfaces 61, 62 are formed as described above, in each lead 20, the recess 50 has a trapezoidal or approximately trapezoidal shape in a cross section perpendicular or approximately perpendicular to the lateral direction in the range between the edge surface E1 and position S1 in the lateral direction of the battery 1, and in the range between position S2 and the recess end surface 51 in the lateral direction of the battery 1.

In addition, each recess 50 of the lead 20 is close to the electrode group 2 from the side where the lid member 5 is located in the height direction of the battery 1. Therefore, each recess 50 of the lead 20 is close to the outer surface of the end of the electrode group 2 on the side where the lid member 5 is located, i.e., the curved surface 14 of the electrode group 2, and faces the curved surface 14 of the electrode group 2 from the side where the lid member 5 is located. Here, as described above, each recess 50 of the lead 20 has a recess bottom surface 57 and inclined surfaces 61, 62. Therefore, each recess 50 of the lead 20 is formed in a shape that follows the curved surface 14 of the electrode group 2, and is formed in a shape that follows the outer surface of the end of the electrode group 2 on the side where the lid member 5 is located.

In addition, in each of the leads 20, the recess 50 is close to the curved surface 14 of the electrode group 2, but the underside of the top plate 35 including the recess 50 does not contact the curved surface 14. That is, the recess 50 of each of the leads 20 is close to the outer surface of the end of the electrode group 2 on the side where the cover member 5 is located, with a gap between the electrode group 2 and the recess 50. In one example, in each of the leads 20, the gap between the recess 57 (recess bottom surface 57 and inclined surfaces 61, 62) and the electrode group 2 is about 0.5 mm. In the battery 1, a part of the electrode group presser 23 abuts against the electrode group 2, so that the electrode group 2 is positioned in the height direction of the battery 1, and the movement of the electrode group 2 in the height direction of the battery 1 is restricted. The abutting portion of the electrode group presser 23 against the electrode group 2 is closer to the electrode group 2 than the recess 50 of each of the leads 20. Therefore, the portion of the electrode group presser 23 that abuts against the electrode group 2 maintains a state in which a gap is formed between each recess 50 of the lead 20 and the electrode group 2 .

In addition, in the negative electrode lead 20A, it is preferable that the end (recess end surface 51) opposite the edge surface (top plate inner edge surface) E1 of the recess 50 is located outside the boundary position Ba between the negative electrode current collector tab 15A and the negative electrode active material containing layer in the lateral direction of the battery 1. In this case, even at the boundary position Ba of the electrode group 2, the recess 50 of the negative electrode lead 20A is close to the outer surface (curved surface 14) of the end on the side where the cover member 5 of the electrode group 2 is located. Similarly, in the positive electrode lead 20B, it is preferable that the end (recess end surface 51) opposite the edge surface E1 of the recess 50 is located outside the boundary position Bb between the positive electrode current collector tab 15B and the positive electrode active material containing layer in the lateral direction of the battery 1. In this case, even at the boundary position Bb of the electrode group 2, the recess 50 of the positive electrode lead 20B is close to the outer surface (curved surface 14) of the end on the side where the cover member 5 of the electrode group 2 is located.

As described above, in this embodiment, a recess 50 is formed on the bottom surface 35 of each top plate of the lead 20, recessed toward the side opposite to the side where the electrode group 2 is located. In each of the leads 20, the recess 50 continues beyond the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31 from the edge surface (top plate inner edge surface) E1 toward the outside in the lateral direction. Therefore, in the internal cavity 8, it is possible to increase the space occupied by the electrode group 2 by the recess amount in each recess 50 of the lead 20. This makes it possible to increase the volume of the electrode group 2 and increase the capacity of the battery 1. In addition, even if the recess 50 is formed in the top plate portion 31 of each of the leads 20, the cross-sectional area of the top plate portion 31 can be secured to be large. Therefore, even if the recess 50 is formed in the top plate portion 31 of each of the leads 20, it is possible to secure a low electrical resistance in the electrical path between the electrode group 2 and each of the electrode terminals 16. Therefore, in this embodiment, the capacity of the battery 1 can be increased without increasing the electrical resistance in the electrical paths between the electrode group 2 and each of the electrode terminals 16 .

In this embodiment, each recess 50 of the lead 20 is formed by the recess bottom surface 57 and the inclined surfaces 61, 62 into a shape that follows the outer surface of the end of the electrode group 2 on the side where the cover member 5 is located, i.e., a shape that follows the curved surface 14 of the electrode group 2. This makes it possible to appropriately increase the dimension of the electrode group 2 in the height direction of the battery 1 by the amount of recession at each recess 50 of the lead 20, and makes it possible to appropriately increase the volume of the electrode group 2. This makes it possible to appropriately increase the capacity of the battery 1.

In addition, in the electrode group 2, the boundary position Ba between the negative electrode current collector tab 15A and the negative electrode active material-containing layer in the horizontal direction of the battery 1, and the boundary position Bb between the positive electrode current collector tab 15B and the positive electrode active material-containing layer in the horizontal direction of the battery 1 are specified. In the battery 1, it is preferable that the end (recess end surface 51) opposite the edge surface (top plate inner edge surface) E1 of each recess 50 of the lead 20 is located outside the boundary position (corresponding one of Ba and Bb) in the horizontal direction of the battery 1. This makes it possible to further appropriately increase the dimension of the electrode group 2 in the height direction of the battery 1, and further appropriately increase the volume of the electrode group 2.

In addition, each recess 50 of the lead 20 approaches the electrode group 2 from the side where the lid member 5 is located in the height direction, with a gap between the electrode group 2 and the recess 50. This effectively prevents the electrode group 2 from contacting the bottom surface 35 (recess 50) of each top plate of the lead 20. Here, when the battery 1 is in use, if the outer container 3 expands due to gas generated in the internal cavity 8, the electrode group 2 may vibrate in the depth direction of the battery 1. In this embodiment, since the bottom surface 35 of each top plate of the lead 20 is effectively prevented from contacting the electrode group 2 as described above, interference between the bottom surface 35 of each top plate of the lead 20 and the vibrating electrode group 2 is effectively prevented when the outer container 3 is in an expanded state. This effectively prevents wear of the top plate portion 31 of each lead 20 and damage to the electrode group 2.

In addition, in each recess 50 of the lead 20, the recess bottom surface 57 is formed along the horizontal direction through the through hole 37 (the connection position of the electrode terminal 16 to the top plate portion 31). In each recess 50 of the lead 20, the recess bottom surface 57 is formed in a planar or approximately planar shape facing the side where the electrode group 2 is located in the height direction of the battery 1, and the opening of the through hole 37 is formed in the recess bottom surface 57. As a result, in each of the leads 20, the crimped portion (plastically deformed portion) of the corresponding one of the electrode terminals 16 is joined to the recess bottom surface 57, so that the entire joint portion to the corresponding one of the electrode terminals 16 can be formed on the recess bottom surface 57. That is, in each of the leads 20, the joint portion to the corresponding one of the electrode terminals 16 can be formed on the same or approximately the same plane. This improves the work efficiency in the work of connecting each of the leads 20 to the corresponding one of the electrode terminals 16, and improves the work efficiency in manufacturing the battery 1. Additionally, each of the leads 20 is appropriately connected to a corresponding one of the electrode terminals 16 .

In addition, in each recess 50 of the lead 20, the recess bottom surface 57 has an enlarged portion 58 in which the dimension of the recess bottom surface 57 along the depth direction of the battery 1 is enlarged compared to other portions of the recess bottom surface 57, and the through hole 37 opens in the enlarged portion 58. By forming an opening of the through hole 37 in the enlarged portion 58, it becomes easier to join the corresponding one of the electrode terminals 16 to the recess bottom surface 57 in each of the leads 20. This further improves the efficiency of the work of connecting each of the leads 20 to the corresponding one of the electrode terminals 16, and each of the leads 20 is more appropriately connected to the corresponding one of the electrode terminals 16.

In addition, in each of the leads 20, the end (recess end surface 51) opposite the edge surface (top plate inner edge surface) E1 of the recess 50 is located between the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31 and the connection position of each of the leg plate portions 32 and 33 to the top plate portion 31 in the horizontal direction. Therefore, on the bottom surface 35 of the top plate of each of the leads 20, each of the leg plate portions 32 and 33 is connected to a relay portion 52 that is not recessed toward the side opposite to the side where the electrode group 2 is located. By connecting the leg plate portions 32 and 33 to the non-recessed relay portion 52, in the formation of each of the leads 20, it becomes easier to bend each of the leg plate portions 32 and 33 relative to the top plate portion 31 by bending. Therefore, the work efficiency in the manufacture of each of the leads 20 is improved.

In addition, on the underside top surface 35 of each lead 20, one of the pair of current collecting tabs 15 may come into contact with the relay portion 52. However, in the electrode group 2, unlike the portion (coated portion) between the boundary positions Ba and Bb including the curved surface 14, each of the current collecting tabs 15 does not significantly affect the performance of the battery 1 even if each of the current collecting tabs 15 is deformed due to contact with the underside top surface 35 of the corresponding one of the leads 20.

(Modification)
6, in each lead 20, the end of the recess 50 opposite to the edge surface (top plate inner edge surface) E1 is located on the edge surface (top plate outer edge surface) E2. Therefore, in this modification, in the top plate underside 35 of each lead 20, the recess 50 continues laterally outward from the edge surface E1 to the edge surface E2 beyond the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31 and the connection positions of the leg plate portions 32, 33 to the top plate portion 31. In this modification as well, in the top plate underside 35 of each lead 20, the recess 50 is recessed toward the side opposite to the side where the electrode group 2 is located.

In a modified example, only one of the leg plate portions 32, 33 may be provided in each of the leads 20. In this case, too, a recess 50 is formed in the underside 35 of the top plate of each of the leads 20 in the same manner as in any of the previously described embodiments.

7, a leg plate portion 70 is provided in each of the leads 20 instead of the leg plate portions 32 and 33. In each of the leg plate portions 70 of the leads 20, a plate length direction, a plate width direction intersecting (perpendicular or approximately perpendicular) with the plate length direction, and a plate thickness direction intersecting (perpendicular or approximately perpendicular) with both the plate length direction and the plate width direction are specified. In one example such as FIG. 7, in each of the leads 20, the plate length direction of each of the leg plate portions 70 coincides or approximately coincides with the plate thickness direction of the top plate portion 31, the plate width direction of the leg plate portion 70 coincides or approximately coincides with the plate width direction of the top plate portion 31, and the plate thickness direction of the leg plate portion 70 coincides or approximately coincides with the plate length direction of the top plate portion 31.

In each of the leads 20, the leg plate portion 70 is connected to the top plate portion 31 at a position outside the connection position of the electrode terminal 16 in the lateral direction of the battery 1, and is connected to the top plate portion 31 at the edge surface (outer edge surface of the top plate) E2. In each of the leads 20, the leg plate portion 70 is bent relative to the top plate portion 31 at the connection position to the top plate portion 31, and extends along the height direction of the battery 1 from the connection position to the top plate portion 31 (the bending position relative to the top plate portion 31). In each of the leads 20, the leg plate portion 70 is bent relative to the top plate portion 31 toward the side where the bottom wall 6 is located, and the bending line at the bending position of the leg plate portion 70 relative to the top plate portion 31 is along the depth direction of the battery 1 (the plate width direction of the top plate portion 31).

In each of the leads 20, the leg plate portion 70 has a pair of leg main surfaces 71, 72. In each of the leg plate portions 70 of the leads 20, the leg main surface 71 faces the inside of the lateral direction of the battery 1 and faces one side of the plate thickness direction of the leg plate portion 70. In each of the leg plate portions 70 of the leads 20, the leg main surface 72 faces the opposite side of the leg main surface 71 in the lateral direction of the battery 1 (plate thickness direction of the leg plate portion 70) and faces the outside of the lateral direction of the battery 1. In each of the leads 20, at the connection position of the leg plate portion 70 to the top plate portion 31, the leg main surface 71 is connected to the top plate lower surface 35, and the leg main surface 72 is connected to the top plate upper surface 36. In each of the leg plate portions 70 of the leads 20, the leg main surface 72 faces the side where the peripheral wall 7 (corresponding one of the side walls 11) is located and faces the outer periphery of the internal cavity 8. In addition, in each leg plate portion 70 of the lead 20, the leg main surface 71 faces the inner periphery of the internal cavity 8, and faces the side where the electrode group 2 is located. In each lead 20, the dimension between the leg main surfaces 71, 72 is defined as the plate thickness of the leg plate portion 70.

In each of the leads 20, the leg plate portion 70 has edge surfaces (leg edge surfaces) E9 and E10. In each of the leg plate portions 70, the edge surface E9 forms one end of the battery 1 in the depth direction (the plate width direction of the leg plate portion 70), and the edge surface E10 forms the end opposite the edge surface E9 in the depth direction of the battery 1. Therefore, in each of the leads 20, each of the leg main surfaces 71 and 72 extends along the depth direction from the edge surface E9 to the edge surface E10, and the leg plate portion 70 extends from the edge surface E9 to the edge surface E10 toward the outside in the depth direction of the battery 1. In this modified example, in each of the current collecting tabs 15, the bundling portion of the multiple strip portions is formed at only one location. In each of the current collecting tabs 15, the bundling portion of the strip portion is joined to the corresponding one of the leads 20 at the edge surface of the leg plate portion 70 (the corresponding one of E9 and E10). Each of the current collecting tabs 15 may be directly bonded to a corresponding one of the leads 20, or may be bonded to a corresponding one of the leads 20 via a backup lead or the like.

In this modification, the recess 50 continues laterally outward from the edge surface E1 on the underside 35 of the top plate of each lead 20 beyond the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31. Also, in this modification, in each lead 20, the end (recess end surface 51) opposite the edge surface (top plate inner edge surface) E1 of the recess 50 is located between the connection position of the electrode terminal 16 to the top plate portion 31 and the connection position of the leg plate portion 70 to the top plate portion 31 in the lateral direction of the battery 1.

In one modification, a leg plate portion 70 is provided in each of the leads 20, as in the second modification. In the top plate underside 35 of each of the leads 20, the recess 50 is formed continuously along the lateral direction up to the connection position of the leg plate portion 70 to the top plate portion 31. In this case, too, in the top plate underside 35 of each of the leads 20, the recess 50 continues from the edge surface E1 laterally outward beyond the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31.

In the above-mentioned embodiment, each recess 50 of the lead 20 is formed by the recess bottom surface 57 and the inclined surfaces 61, 62 in a shape that follows the outer surface of the end of the electrode group 2 on the side where the cover member 5 is located, but the configuration in which each recess 50 of the lead 20 is formed in a shape that follows the outer surface of the end of the electrode group 2 on the side where the cover member 5 is located is not limited to this. In one modified example, the inclined surfaces 61, 62 are not provided in each recess 50 of the lead 20, and each recess 50 of the lead 20 is formed in a curved shape that follows the curved surface 14 of the electrode group 2, except for the range between positions S1 and S2 in the lateral direction of the battery 1 (plate length direction of the top plate portion 31). In this case, each recess 50 of the lead 20 becomes arc-shaped in a cross section perpendicular or approximately perpendicular to the lateral direction of the battery 1 (axial direction of the electrode group 2), except for the range between positions S1 and S2 in the lateral direction of the battery 1 (plate length direction of the top plate portion 31). However, even in this modified example, each recess 50 of the lead 20 has a recess bottom surface 57 formed in a planar or approximately planar shape facing the side on which the electrode group 2 is located. In each recess 50 of the lead 20, the recess bottom surface 57 is formed in the range between positions S1 and S2 in the lateral direction of the battery 1, and is formed along the lateral direction through the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31.

In a modified example, the electrode group 2 has a stack structure or the like, and the curved surface 14 is not formed on the outer surface of the end of the electrode group 2 on the side where the cover member 5 is located. In this case, too, a recess 50 is formed on the underside 35 of each top plate of the lead 20. In each of the leads 20, the recess 50 is recessed on the opposite side to the side where the electrode group 2 is located, with respect to other parts of the underside 35 of the top plate and the surface connected to the underside 35 of the leg plate portions 32, 33 (leg plate portion 70). In this case, too, in the underside 35 of each top plate of the lead 20, the recess 50 continues from the edge surface E1 laterally outward beyond the connection position (through hole 37) of the electrode terminal 16 to the top plate portion 31. In addition, on the underside 35 of the top plate of each lead 20, the recess 50 is formed in a shape that conforms to the outer surface of the end portion on the side where the cover member 5 of the electrode group 2 is located, and is close to the electrode group 2 from the side where the cover member 5 is located in the height direction, with a gap between the electrode group 2 and the recess 50.

In addition, in a configuration in which the electrode group 2 does not have a curved surface 14, the recess 50 may be formed on the top plate underside 35 of each lead 20 across the entire dimension (full width) of the plate width direction of the top plate portion 31 (depth direction of the battery 1). In this case, the top plate underside 35 of each lead 20 does not have adjacent portions 55, 56, etc., and the recess 50 is formed along the width direction of the top plate portion 31 from the edge surface E3 to the edge surface E4. In this case, in each lead 20, the recess 50 is recessed on the side opposite to the side on which the electrode group 2 is located, with respect to other parts of the top plate underside 35 and the surfaces of the leg plate portions 32, 33 (leg plate portions 70) connected to the top plate underside 35.

In addition, it is not necessary for both the negative electrode side lead between the negative electrode current collector tab 15A and the negative electrode terminal 16A and the negative electrode side lead between the positive electrode current collector tab 15B and the positive electrode terminal 16B to have the same configuration as any of the leads 20 in the above-mentioned embodiments and modified examples. In other words, it is sufficient that at least one of the negative electrode side lead and the positive electrode side lead has the same configuration as any of the leads 20 in the above-mentioned embodiments and modified examples.

According to at least one of these embodiments or examples, the recess on the underside of the top plate of the top plate portion of the battery lead is recessed toward the side opposite to the side where the electrode group is located. The recess is continuously formed from the inner edge surface of the top plate portion toward the outside in the lateral direction beyond the connection position of the electrode terminal to the top plate portion. This makes it possible to provide a battery that can increase capacity without increasing the electrical resistance in the electrical path between the electrode group and the electrode terminal.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.
The following are additional notes.
[1] An outer container having a bottom wall and a peripheral wall, and an internal cavity that opens to the side opposite to the side where the bottom wall is located in the height direction;
a cover member attached to the peripheral wall of the outer container in a state of closing an opening of the internal cavity;
an electrode group that includes a current collecting tab protruding outward in a lateral direction intersecting the height direction and is housed in the internal cavity of the outer container;
an electrode terminal exposed to the outside on an outer surface of the cover member;
a lead that electrically connects the current collecting tab of the electrode group and the electrode terminal;
Equipped with
the lead is disposed between the lid member and the electrode group in the internal cavity, and includes a top plate portion to which the electrode terminal is connected, and a leg plate portion bent relative to the top plate portion toward a side where the bottom wall is located and joined to the current collecting tab,
The top plate portion includes a top plate inner edge surface that forms an inner end of the top plate portion in the lateral direction, a top plate underside surface that faces the electrode group, and a recess that is recessed in the top plate underside toward the side opposite to the side where the electrode group is located and is formed continuously from the top plate inner edge surface toward the outside in the lateral direction beyond a connection position of the electrode terminal to the top plate portion.
battery.
[2] The battery according to [1], wherein the recess is formed in a shape that conforms to the outer surface of the end portion of the electrode group on which the lid member is located.
[3] The battery according to [1] or [2], wherein the recess is adjacent to the electrode group from the side where the lid member is located in the height direction, with a gap between the recess and the electrode group.
[4] The top plate portion has a top plate upper surface facing the opposite side to the top plate lower surface,
a through hole is formed in the top plate portion, the through hole penetrating the top plate portion along the height direction from the top surface of the top plate to the bottom surface of the top plate, and the electrode terminal is inserted into the through hole;
the recess has a bottom surface formed in a planar shape facing the side on which the electrode group is located and extending along the lateral direction through the connection position of the electrode terminal to the top plate portion,
The through hole opens toward the bottom surface of the recess on which the electrode group is located.
A battery according to any one of [1] to [3].
[5] The bottom surface of the recess includes a dimension-enlarged portion in which a dimension of the bottom surface of the recess along a depth direction intersecting both the height direction and the lateral direction is enlarged compared to other portions of the bottom surface of the recess,
The through hole opens in the enlarged portion.
[4] Battery.
[6] The leg plate portion is connected to the top plate portion at a position outside the connection position of the electrode terminal to the top plate portion in the lateral direction,
an end of the recess opposite to the inner edge surface of the top plate is located between the connection position of the electrode terminal to the top plate portion and the connection position of the leg plate portion to the top plate portion in the lateral direction;
A battery according to any one of [1] to [5].
[7] A battery according to any one of [1] to [6], wherein the thickness of the top plate portion in the area where the recess is formed is thinner than the thickness of the top plate portion in areas other than the area where the recess is formed, and the thickness of the leg plate portion.
[8] A battery according to any one of [1] to [7], wherein the hardness of the top plate portion in the area where the recess is formed is greater than the hardness of the top plate portion in the area other than the area where the recess is formed, and greater than the hardness of the leg plate portion.
[9] The underside of the top plate includes a first adjacent portion adjacent to the recess from one side in a depth direction intersecting both the height direction and the width direction, and a second adjacent portion adjacent to the recess from an opposite side to the first adjacent portion in the depth direction,
the recess is recessed toward an opposite side to a side on which the electrode group is located with respect to the first adjacent portion and the second adjacent portion in a state where the recess is sandwiched between the first adjacent portion and the second adjacent portion in the depth direction;
A battery according to any one of [1] to [8].
[10] The electrode group includes a current collector and an active material-containing layer supported on a surface of the current collector,
the current collector of the electrode group includes the current collecting tab as a portion not carrying the active material-containing layer,
the current collecting tab protrudes outward in the lateral direction relative to the active material-containing layer in the electrode group,
an end of the recess opposite to the inner edge surface of the top plate is located outside a boundary position between the current collecting tab and the active material-containing layer in the lateral direction;
A battery according to any one of [1] to [9].
[11] The current collecting tabs include a negative electrode current collecting tab protruding to one side in the lateral direction from the electrode group, and a positive electrode current collecting tab protruding to the side opposite to the side from which the negative electrode current collecting tab protrudes from the electrode group,
the electrode terminals include a negative electrode terminal and a positive electrode terminal disposed on the outer surface of the lid member away from the negative electrode terminal;
the lead electrically connects the negative electrode current collector tab and the negative electrode terminal, or the lead electrically connects the positive electrode current collector tab and the positive electrode terminal;
A battery according to any one of [1] to [10].

Claims (10)

an outer container including a bottom wall and a peripheral wall, the outer container having an internal cavity that opens to a side opposite to the side where the bottom wall is located in a height direction;
a cover member attached to the peripheral wall of the outer container in a state of closing an opening of the internal cavity;
an electrode group that includes a current collecting tab protruding outward in a lateral direction intersecting the height direction and is housed in the internal cavity of the outer container;
an electrode terminal exposed to the outside on an outer surface of the cover member;
a lead that electrically connects the current collecting tab of the electrode group and the electrode terminal;
Equipped with
the lead is disposed between the lid member and the electrode group in the internal cavity, and includes a top plate portion to which the electrode terminal is connected, and a leg plate portion bent relative to the top plate portion toward a side where the bottom wall is located and joined to the current collecting tab,
the top plate portion includes a top plate inner edge surface that forms an inner end of the top plate portion in the lateral direction, a top plate underside surface that faces the electrode group, and a recess that is recessed in the top plate underside toward the side opposite to the side on which the electrode group is located and is formed continuously from the top plate inner edge surface toward the outside in the lateral direction beyond a connection position of the electrode terminal to the top plate portion ,
The thickness of the top plate portion in the region where the recess is formed is thinner than the thickness of the top plate portion in the region other than the region where the recess is formed and the thickness of the leg plate portion.
battery. The battery of claim 1, wherein the recess is formed in a shape that conforms to the outer surface of the end of the electrode group on the side where the lid member is located. The battery of claim 1 or 2, wherein the recess is adjacent to the electrode group from the side where the lid member is located in the height direction, with a gap between the recess and the electrode group. The top plate portion includes a top plate upper surface facing the opposite side to the top plate lower surface,
a through hole is formed in the top plate portion, the through hole penetrating the top plate portion along the height direction from the top surface of the top plate to the bottom surface of the top plate, and the electrode terminal is inserted into the through hole;
the recess has a bottom surface formed in a planar shape facing the side on which the electrode group is located and extending along the lateral direction through the connection position of the electrode terminal to the top plate portion,
The through hole opens toward the bottom surface of the recess on which the electrode group is located.
The battery of any one of claims 1 to 3. the bottom surface of the recess includes a dimension-enlarged portion in which a dimension of the bottom surface of the recess along a depth direction intersecting both the height direction and the lateral direction is enlarged compared to other portions of the bottom surface of the recess,
The through hole opens in the enlarged portion.
5. The battery of claim 4. the leg plate portion is connected to the top plate portion at a position outside the connection position of the electrode terminal to the top plate portion in the lateral direction;
an end of the recess opposite to the inner edge surface of the top plate is located between the connection position of the electrode terminal to the top plate portion and the connection position of the leg plate portion to the top plate portion in the lateral direction;
6. The battery of claim 1 . 7. A battery according to claim 1, wherein the hardness of the top plate portion in the area where the recess is formed is harder than the hardness of the top plate portion in the area other than the area where the recess is formed, and the hardness of the leg plate portion. The underside of the top plate includes a first adjacent portion adjacent to the recess from one side in a depth direction intersecting both the height direction and the width direction, and a second adjacent portion adjacent to the recess from an opposite side to the first adjacent portion in the depth direction,
the recess is recessed toward an opposite side to a side on which the electrode group is located with respect to the first adjacent portion and the second adjacent portion in a state where the recess is sandwiched between the first adjacent portion and the second adjacent portion in the depth direction;
The battery of any one of claims 1 to 7 . the electrode group includes a current collector and an active material-containing layer supported on a surface of the current collector,
the current collector of the electrode group includes the current collecting tab as a portion not carrying the active material-containing layer,
the current collecting tab protrudes outward in the lateral direction relative to the active material-containing layer in the electrode group,
an end of the recess opposite to the inner edge surface of the top plate is located outside a boundary position between the current collecting tab and the active material-containing layer in the lateral direction;
9. The battery of claim 1. the current collecting tabs include a negative electrode current collecting tab that protrudes from the electrode group to one side in the lateral direction, and a positive electrode current collecting tab that protrudes from the electrode group to a side opposite to the side from which the negative electrode current collecting tab protrudes,
the electrode terminals include a negative electrode terminal and a positive electrode terminal disposed on the outer surface of the lid member away from the negative electrode terminal;
the lead electrically connects the negative electrode current collector tab and the negative electrode terminal, or the lead electrically connects the positive electrode current collector tab and the positive electrode terminal;
10. The battery of claim 1.

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