Secondary batteries

Abstract

To provide a secondary battery that is easily assembled.SOLUTION: A secondary battery comprises: an outer container that has a lid body; an electrode body; output terminals that are provided on the lid body and each have a male screw part; and leads that are provided between the electrode body and the lid body inside the container. The leads each have a plate-like junction facing the lid body, and a female screw part provided through the junction. The male screw part of the output terminal is screwed into the female screw part through the lid body, and is electrically connected with the junction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] Embodiments of the present invention relate to secondary batteries.

Background Art

[0002] In recent years, as a power source for electronic devices and electric vehicles, secondary batteries with high energy density, such as lithium-ion secondary batteries, have been widely used. Such a secondary battery is configured by housing an electrode body and a non-aqueous electrolyte in a rectangular parallelepiped exterior container made of aluminum or an aluminum alloy. An output terminal for the positive electrode or the negative electrode is provided on the lid of the exterior container. The output terminal is connected to the electrode body via a lead provided inside the exterior container. As a method for connecting the output terminal and the lead, fastening with a screw, welding, etc. are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem of the present embodiment is to provide a secondary battery that is easy to assemble.

Means for Solving the Problems

[0005] A secondary battery according to one embodiment includes an outer casing having a pair of spaced-apart opposing long side walls and a lid fixed to one end of the pair of long side walls; an electrode body having a current collecting tab and housed inside the outer casing; an output terminal provided on the lid and having a first male screw portion; a plate-shaped first joint portion provided inside the outer casing between the electrode body and the lid, electrically connecting the current collecting tab and the output terminal and facing the lid; a female screw portion provided through the first joint portion; and extending from the first joint portion along the inner surface of one of the long side walls. 2nd joint A lead having a mounting portion extending from the first joint portion along the inner surface of the other long side wall, and provided inside the outer container between the electrode body and the lid, and positioned facing the inner surface of one of the long side walls, 2nd joint The first insulator has an inner surface that engages with the outer surface and an engaging projection protruding from the inner surface, and the second insulator is provided inside the outer container between the electrode body and the lid, positioned opposite the inner surface of the other long side wall, and has an inner surface that engages with the outer surface of the mounting portion and an engaging projection protruding from the inner surface, wherein the lead Second joint and Each of the mounting portions has an engaged portion that engages with the engaging projection, and the engaged portion is The second joint and the mounting portion have engagement recesses formed in one of them, and the other has a mounting hole formed through the second joint and the mounting portion. The first male threaded portion of the output terminal is screwed into the female threaded portion through the cover and electrically connected to the first joint. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a perspective view showing the external appearance of a secondary battery according to one embodiment. [Figure 2] Figure 2 is an exploded perspective view of the secondary battery shown in Figure 1. [Figure 3] Figure 3 is a perspective view showing the lead. [Figure 4] Figure 4 is a perspective view of the lead shown in Figure 3, viewed from the back side. [Figure 5] Figure 5 is a cross-sectional view along line A-A in Figure 1. [Figure 6] Figure 6 is a perspective view showing an example of the use of the secondary battery according to this embodiment. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. Note that the disclosure is merely an example, and modifications that a person skilled in the art could easily conceive of while maintaining the spirit of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the drawings and descriptions, the width, thickness, shape, etc., of each part may be represented schematically compared to the actual appearance, but this is merely an example and does not limit the interpretation of the present invention. Also, in this specification and in each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0008] The secondary battery according to this embodiment will be described in detail below. Figure 1 is a perspective view showing the external appearance of a secondary battery according to an embodiment. As shown in Figure 1, the secondary battery 10 is a non-aqueous electrolyte secondary battery such as a lithium-ion battery, and comprises a flat, substantially rectangular parallelepiped outer container 12 and an electrode body 30, described later, housed inside the outer container 12 together with a non-aqueous electrolyte. The outer container 12 is, for example, a resin container made of resin. The outer container 12 has a container body 16 with an open top end and a plate-shaped lid 14 fixed to the container body 16 and closing the opening of the container body 16, and the inside is airtight. In this embodiment, as described above, the container body 16 is made of resin and the lid 14 is made of a resin having electrical insulating properties.

[0009] The lid 14 is provided with a pair of output terminals 20 and an inlet 29. Here, we define the longitudinal direction of the lid 14 and the container body 16 as X, the width direction of the lid 14 and the container body 16 perpendicular to the longitudinal direction X as Y, and the height direction of the container body 16 as Z. Furthermore, the outer container 12 is not limited to resin; it may also be a metal container made of an aluminum alloy, iron, or stainless steel.

[0010] Figure 2 is an exploded perspective view of the secondary battery shown in Figure 1. As shown in Figure 2, the container body 16 of the outer container 12 has a rectangular long side wall 16a, a rectangular long side wall 16b that is spaced apart from and parallel to the long side wall 16a, a pair of opposing short side walls 16c, and a bottom wall 16d. The upper edges of the pair of long side walls 16a and 16b and the upper edges of the pair of short side walls 16c define a rectangular upper opening 17. The lid 14 is formed in the shape of a rectangular plate, approximately the same size as the upper opening 17. The lid 14 is fixed to the container body 16 with the upper opening 17 closed. The lid 14 has a pair of circular through-holes 26. Each through-hole 26 is a through-hole formed in the lid 14 in the height direction (thickness direction) Z. The pair of through-holes 26 are located at both ends of the lid 14 in the longitudinal direction X and are spaced apart from each other in the longitudinal direction X. The inlet 29 is located between the pair of through-holes 26. After the non-aqueous electrolyte is injected into the outer container 12 through the inlet 29, the inlet 29 is sealed, for example, with a disc-shaped sealing lid 25. The output terminal 20 is formed in a columnar shape extending along the height direction Z, and integrally has a first male threaded portion 20a formed at one end, a second male threaded portion 20b formed at the other end, and an annular flange portion 20c located between the first male threaded portion 20a and the second male threaded portion 20b. The flange portion 20c is formed, for example, in a hexagonal shape and constitutes a nut. The output terminal 20 is attached to the cover 14 with the first male threaded portion 20a inserted through the through hole 26 of the cover 14. As shown in Figure 2, the electrode body 30 housed in the outer container 12 is constructed by alternately stacking, for example, a plurality of sheet-shaped positive electrode plates and a plurality of negative electrode plates with a separator in between. The positive electrode plate has a plate-shaped positive electrode current collector, a positive electrode active material layer formed on at least one surface of the positive electrode current collector, and a positive electrode current collector tab 32a extending in the height direction Z from one end of the positive electrode current collector. The negative electrode plate has a plate-shaped negative electrode current collector, a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and a negative electrode current collector tab 32b extending in the height direction Z from one end of the negative electrode current collector. The separator has electrical insulating properties and electrically insulates the positive electrode plate from the negative electrode plate. The current collectors and current collector tabs of the positive and negative electrode plates are, in one example, formed from metal foil with a thickness of approximately 5 to 50 μm. The material of the metal foil may vary depending on the type of active material used in the positive and negative electrodes, but for example, metal foils such as aluminum, aluminum alloys, copper, and copper alloys, or conductive resin films can be used.

[0011] Multiple positive electrode current collector tabs 32a extend outward from one end of the electrode body (electrode group) 30 and are stacked in the width direction Y. The extended ends of the multiple positive electrode current collector tabs 32a may be held together by a U-shaped backup lead 34. The positive electrode current collector tabs 32a are located on one end side of the electrode body 30 in the longitudinal direction X. Multiple negative electrode current collector tabs 32b extend outward from one end of the electrode body 30 and are stacked in the width direction Y. The extended portions of the multiple negative electrode current collector tabs 32b are held together by a U-shaped backup lead 34, and the negative electrode current collector tabs 32b are located on the other end side of the electrode body 30 in the longitudinal direction X.

[0012] Thus, the positive electrode current collector tab 32a and the negative electrode current collector tab 32b extend in the same direction from one end of the electrode body 30 and are positioned with a gap between them in the longitudinal direction X of the electrode body 30. The electrode body 30 configured as described above is housed inside the container body 16 with one end face of the electrode body 30, the positive electrode current collecting tab 32a, and the negative electrode current collecting tab 32b facing the lid body 14 in the height direction Z. A predetermined interval is provided between one end face of the electrode body 30 and the lid body 14.

[0013] As shown in FIG. 2, the secondary battery 10 includes a pair of insulators 36, an adhesive member 38, a positive electrode lead 40A, and a negative electrode lead 40B provided in the space between the electrode body 30 and the lid body 14 inside the outer container 12. The insulator 36 is formed of, for example, a resin having electrical insulation properties. The insulator 36 is formed in a frame shape so as to surround the space between the lid body 14 and the electrode body 30 and is disposed in contact with the inner surface of the container body 16. The insulator 36 electrically insulates between the positive electrode lead 40A, the negative electrode lead 40B, the positive electrode current collecting tab 32a, and the negative electrode current collecting tab 32b and the container body 16, and has a function as a spacer for maintaining the interval between the lid body 14 and the electrode body 30. In one example, the insulator 36 is divided into a pair of insulators, and a frame body is formed by combining them. Each insulator 36 is formed in an elongated plate shape extending in the longitudinal direction X, and both end portions in the longitudinal direction X are bent in the width direction Y. The insulator 36 has an outer surface that abuts against the inner surface of the container body 16, an inner surface on the opposite side, two ribs 36a protruding from the inner surface at the central portion in the longitudinal direction X, and a plurality of, for example, four engaging protrusions 36b protruding from the inner surface between the rib 36a and one end.

[0014] The adhesive member 38 is, for example, a strip-shaped adhesive tape. The adhesive member 38 is provided on the outer surface of each insulator 36, the upper surface of each insulator 36 facing the lid body 14, and a pair of side surfaces in the width direction Y of the electrode body 30. However, in one example, it is provided so as to be located on the upper surface of the rib 36a of each insulator 36. The adhesive member 38 holds the state in which each insulator 36 and the electrode body 30 are integrated.

[0015] The positive lead 40A is located between the insulators 36 in the width direction Y and electrically connects the output terminal 20 to the positive current collector tab 32a. The negative lead 40B is located between the insulators 36 in the width direction Y and electrically connects the output terminal 20 to the negative current collector tab 32b. In this embodiment, the positive lead 40A and the negative lead 40B have the same configuration and shape. The configuration of the leads of the secondary battery 10 according to this embodiment will be described in detail below, with the positive electrode lead 40A being a representative example.

[0016] Figure 3 is a perspective view showing the positive electrode lead, and Figure 4 is a perspective view of the positive electrode lead from a different direction. As shown in Figures 3 and 4, the positive electrode lead 40A is constructed by bending a conductive metal plate. In one example, the positive electrode lead 40A integrally includes a rectangular first joint portion 41, a rectangular second joint portion 45 extending substantially perpendicularly to the first joint portion 41 from one side edge of the first joint portion 41, and rectangular mounting portions 43 extending substantially perpendicularly to the first joint portion 41 from both ends of the other side edge of the first joint portion 41. The first joint portion 41 is formed in the shape of a rectangular plate having a pair of side edges extending in the longitudinal direction X, and has an upper surface 41a facing the lid 14 and a lower surface 41b located on the opposite side of the upper surface 41a. The first joint portion 41 has a pair of first engaging projections 48 that protrude in the planar direction from both ends of one side edge beyond the second joint portion 45, and a second engaging projection 49 that protrudes in the planar direction from the center of the other side edge beyond the mounting portion 43. Furthermore, the first joint portion 41 has a cylindrical projection 47 protruding from approximately the center of the lower surface 41b, and a female threaded portion 42 formed in the height direction Z, penetrating the first joint portion 41 and the projection 47. The female threaded portion 42 is provided for screwing in the first male threaded portion 20a of the output terminal 20. Details of the female threaded portion 42 will be described later in the explanation of the internal structure of the secondary battery 10 shown in Figure 5.

[0017] The second joint portion 45 extends in a plate shape along the height direction Z and is positioned parallel to and opposite the long side wall 16b of the container body 16. A pair of engagement recesses 46 are provided on each of the side edges of the second joint portion 45 extending in the height direction Z. Each engagement recess 46 is formed in a position and size that allows it to engage with the engagement projection 36b of the insulator 36. The positive electrode lead 40A and the insulator 36 are connected when the engagement recess 46 engages with the engagement projection 36b. Each of the mounting portions 43 is positioned parallel to and opposite the long side wall 16a of the container body 16. The mounting portion 43 has a mounting hole 44 formed through it in the width direction Y. The mounting hole 44 is formed in a position and size that allows it to engage with the engaging projection 36b of the insulator 36. The positive electrode lead 40A and the insulator 36 are connected when the mounting hole 44 engages with the engaging projection 36b.

[0018] The internal configuration of the assembled secondary battery 10 is described below. Figure 5 is a cross-sectional view along line A-A in Figure 1. As shown in Figure 5, the outer container 12 has a container body 16 with an open top and a lid 14 that closes the opening of the container body 16. Inside the outer container 12 are the electrode body 30, the positive electrode lead 40A, and a pair of insulators 36. On the other hand, the output terminal 20 is attached to the outside of the outer container 12 (above the lid 14). The electrode body 30 is located between a pair of long side walls 16a, 16b of the container body 16 and has a positive electrode current collector tab 32a that extends toward the lid 14. The tip of the positive electrode current collector tab 32a is held by a backup lead 34 and connected to a second junction 45 of the positive electrode lead 40A. A pair of insulators 36 are arranged in the width direction Y and are located between the electrode body 30 and the lid body 14. The outer surface of each insulator 36 is in contact with the inner surface of the container body 16, and the inner surface of each insulator 36 is in contact with the outer surface of the positive electrode lead 40A.

[0019] The positive electrode lead 40A is located between the electrode body 30 and the cover body 14, and is fixed to the insulator 36 by the engagement of the engagement recess 46 and mounting hole 44 with the engagement projection 36b of each insulator 36 (see Figures 2, 3, and 4 for the engagement recess 46, mounting hole 44, and engagement projection 36b). The positive electrode lead 40A has a first joint portion 41 that is in contact with the inner surface of the cover 14, and a second joint portion that extends substantially perpendicularly to the first joint portion 41 and the cover 14. The first joint portion 41 has a first engaging projection 48, a second engaging projection 49, a projection 47 extending from the lower surface of the first joint portion 41, and a female threaded portion 42 formed through the first joint portion 41 and the projection 47. The positive electrode lead 40A is held by each insulator 36 by the first engaging projection 48 contacting the upper surface of one insulator 36 and the second engaging projection 49 contacting the upper surface of the other insulator 36. The protrusion 47 can be formed, for example, by burring. The length L1 of the female thread portion 42 in the direction along the axis 42a (length from the upper surface 41a to the opposite end surface 47a) is greater than the plate thickness T1 of the positive lead 40A. Here, plate thickness T1 refers to the distance in the height direction Z between the upper surface 41a and the lower surface 41b of the first joint portion 41. For example, the length L1 of the female thread portion 42 is 2 to 2.5 mm, and the plate thickness T1 of the first joint portion 41 is about 1 mm.

[0020] However, if the plate thickness T1 of the first joint 41 is 2 mm or more, it is not necessary to provide the protrusion 47. If the protrusion 47 is not provided, the length L1 of the female thread portion 42 and the plate thickness T1 of the first joint 41 are equal. The second joint 45 is joined to the positive electrode current collector tab 32a and the backup lead 34. The joining method can be, for example, laser welding, ultrasonic welding, or resistance welding.

[0021] The output terminal 20 has a first male threaded portion 20a, a second male threaded portion 20b, and a flange portion 20c located between the first male threaded portion and the second male threaded portion. The first male threaded portion 20a is screwed into the female threaded portion 42 of the positive lead 40A through the through-hole 26 of the cover 14 until the flange portion 20c abuts against the outer surface of the cover 14. As a result, the output terminal 20 and the positive lead 40A are fixed to the outer and inner surfaces of the cover 14, respectively, and the output terminal 20 is electrically connected to the positive lead 40A.

[0022] The assembly procedure for the secondary battery according to this embodiment will be described. As shown in Figure 2, first, prepare the outer casing 12, electrode body 30, leads (positive lead 40A and negative lead 40B), insulator 36, adhesive member 38, and output terminal 20. Next, connect the positive electrode current collector tab 32a of the electrode body 30 to the positive lead 40A, and connect the negative electrode current collector tab 32b to the negative lead 40B. Next, each insulator 36 is attached to the outside of the lead in the width direction Y. At this time, the mounting hole 44 of the lead is engaged with the engaging projection 36b of one insulator 36, and the engaging recess 46 of the lead is engaged with the engaging projection 36b of the other insulator 36 (see Figures 3 and 4). Subsequently, the upper surface of the insulator 36 facing the cover 14, the outer surface of each insulator 36, and the outer surface of the electrode body 30 are covered and bonded with the adhesive member 38. However, in this embodiment, the upper surface of the insulator 36 includes the upper surface of the rib 36a. This allows the electrode body 30, the lead, and the insulator 36 to be held in an integrated state. After integration, the integrated electrode body 30, lead, and insulator 36 are placed inside the container body 16, and the lid 14 is fixed to the upper opening 17 of the container body 16 so as to seal the inside of the container body 16. Finally, each output terminal 20 is inserted through the through hole 26 of the cover 14, and the first male threaded portion 20a of each output terminal 20 is screwed into the female threaded portion 42 of each lead.

[0023] The effects of the secondary battery according to this embodiment will be explained. As shown in Figures 2 and 5, the secondary battery 10 comprises an outer casing 12, an electrode body 30, an output terminal 20, and leads (positive electrode lead 40A and negative electrode lead 40B). Each lead has a plate-shaped first joint portion 41 facing the lid 14, and a female threaded portion 42 that penetrates the first joint portion 41 and the protruding portion 47. The first male threaded portion 20a of the output terminal 20 is screwed into the female threaded portion 42. This allows the secondary battery 10 to be assembled from the bottom up and disassembled from the top down. In other words, all components used in the secondary battery 10 can be accessed from above, resulting in an easy-to-assemble secondary battery 10. Furthermore, since nuts are not required to fix the leads to the output terminal 20, the number of parts can be reduced, and costs can be lowered. As shown in Figure 5, when the lead plate thickness T1 is 2 mm or less, the length of the female thread portion 42 of the lead is greater than the lead plate thickness T1. This ensures sufficient engagement between the first male thread portion 20a of the output terminal 20 and the female thread portion 42 of the lead. Furthermore, since the lead plate thickness T1 can be reduced, weight reduction and cost reduction are possible.

[0024] An example of the use of the secondary battery according to this embodiment will be described. Figure 6 is a perspective view showing an example of the use of the secondary battery 10 according to this embodiment. As shown in Figure 6, the secondary batteries 10 are housed inside the case 50, side by side in the width direction Y, with the lid 14 facing upwards. In other words, in the usage example described here, the output terminal 20 can be attached from above. The secondary battery in this example further includes a connecting member 56, one end of which is fixed to the positive output terminal 20 and the other end of which is fixed to the negative output terminal 20, and a washer 54 provided between the flange portion 20c of the output terminal 20 and the cover 14. The two secondary batteries 10 are electrically connected via a connecting member 56 fixed to a second male threaded portion 20b by tightening a nut 28, a positive terminal output terminal 20, and a negative terminal output terminal 20. The connecting member 56 is, for example, a busbar made of a metal such as aluminum or copper. However, the method of fixing the connecting member 56 to the output terminals 20 is not limited to tightening the second male threaded portion 20b with a nut 28. For example, it is also possible to fix it by welding to the end of the output terminal 20 in the height direction Z on the outside of the outer casing 12. In other words, the output terminals 20 can also be configured without the second male threaded portion 20b.

[0025] While embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. Novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0026] 10...Secondary battery, 12...Outer casing, 14...Lid, 16...Container body, 20...Output terminal, 20a...First male threaded section, 20b...Second male threaded section, 30...Electrode body, 32a...Positive electrode current collector tab, 32b...Negative electrode current collector tab, 36...Insulator, 40A...Positive electrode lead, 40B...Negative electrode lead, 41...First joint, 41a...Top surface, 41b...Bottom surface, 42...Female threaded section, 42a...Axis, 47...Protrusion, 47a...End face, L1...Length, T1...Plate thickness

Claims

1. An outer container having a pair of long side walls that are spaced apart and facing each other, and a lid fixed to one end of the pair of long side walls, An electrode body having a current-collecting tab and housed inside the outer casing, An output terminal provided on the cover and having a first male screw portion, A lead is provided inside the outer container between the electrode body and the lid, electrically connecting the current collector tab and the output terminal, and having a plate-shaped first joint portion facing the lid, a female screw portion provided through the first joint portion, a second joint portion extending from the first joint portion along the inner surface of one of the long side walls, and a mounting portion extending from the first joint portion along the inner surface of the other long side wall, A first insulator is provided inside the outer container between the electrode body and the lid, positioned opposite the inner surface of one of the long side walls, and having an inner surface that engages with the outer surface of the second joint and an engaging projection protruding from the inner surface, The outer container is provided between the electrode body and the lid, and is positioned opposite the inner surface of the other long side wall, and comprises a second insulator having an inner surface that engages with the outer surface of the mounting portion and an engaging projection protruding from the inner surface, The second joint and the mounting portion of the lead each have an engaged portion that engages with the engaging projection, the engaged portion comprising an engaging recess formed in one of the second joint and the mounting portion, and a mounting hole formed through the other of the second joint and the mounting portion. The first male threaded portion of the output terminal is screwed into the female threaded portion through the cover and electrically connected to the first joint. Secondary battery.

2. The first joint of the lead further has an upper surface facing the lid, a lower surface facing the upper surface, and a protruding portion extending from the lower surface. The female thread portion is provided extending from the upper surface to the end face of the protrusion, passing through the first joint and the protrusion. The axial length of the female screw portion is greater than the thickness of the lead plate. The secondary battery according to claim 1.

3. The plate thickness of the lead, excluding the aforementioned protrusion, is less than 2 mm. The secondary battery according to claim 2.

4. The output terminal further has a flange portion that contacts the outer surface of the cover. A secondary battery according to any one of claims 1 to 3.

5. The output terminal is formed in a columnar shape and has a first male threaded portion formed at one end in the axial direction, a second male threaded portion formed at the other end in the axial direction, and a flange portion provided between the first male threaded portion and the second male threaded portion. The secondary battery according to claim 4.

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